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Today’s wind turbines are capable of converting a great amount of energy in the wind into electricity. This is due to the blades, which are developed using state of the art aerodynamic analysis and the other performance enhancing equipment. In this video, we will explore these different sets of technology in a simple, yet scientific, way. \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/qSWm_nprfqE\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003E\u003C\/p\u003EA detailed webpage version of the video is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003EThe Basic Working\u003C\/h2\u003E\u003Cp\u003EFirst, let’s get into its basic working.  You might have noticed that even a breezing wind will turn the gigantic wind turbine blades. But how it is possible ? To get answer for this let's have a close look at the wind turbine blade. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-UrKBF1vKSaw\/VuEvQiH4e_I\/AAAAAAAADqc\/4_tVAiDu83A\/s1600\/Wind_turbine_blade_shape.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 A wind turbine blade is a collection of different airfoil shapes \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  The blade has a lot of airfoil cross sections consisting of different sizes and shapes from the root to tip. The simple airfoil technology makes the wind turbine blade turn. That means that a lift force is produced when a fluid moves over an airfoil. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-QJIYlck0NcY\/VuFWkVY-DYI\/AAAAAAAADsE\/jHJRuJapCs0\/s1600\/airfoil_technology.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 A lift force is generated when flow occurs over an airfoil \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EYou can note from the Fig.1 that at the root, the airfoil shape is super thick. The reason for this is structural rather than the aerodynamics. At the root mechanical strength required is really high due to the high bending moment induced there.  This way, the wind turbine achieves the basic rotation we are accustomed to seeing. \u003C\/p\u003E\u003Ch2\u003EWind Turbine Blade Design\u003C\/h2\u003E\u003Cp\u003EThe design of wind turbine blade is a clever art.There are aerodynamic reasons behind the complex 3 dimensional shape of wind turbine blade. We will see these factors in this section. \u003Ch3\u003EBlade Tilt\u003C\/h3\u003E\u003Cp\u003EJust as in a moving train, you experience things relatively; the moving wind turbine blade also experiences the wind relatively.  For the moving blade, the relative wind velocity shown in first part of Fig 3. To get relative velocity, you have to vectorially subtract blade velocity from the actual wind velocity. You can note a even if the wind velocity is normal relative velocity is always inclined. Therefore, the wind turbine blade is positioned in a tilted manner in order to align with the relative wind speed. This blade tilt is shown in second part of Fig.3.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-kwJoHck9_04\/VuFWkbc5MHI\/AAAAAAAADr0\/_2h3Phgv-5k\/s1600\/blade_tilt_relative_velocity.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 The concept of relative wind velocity and blade tilting \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003Ch3\u003EBlade Twist\u003C\/h3\u003E\u003Cp\u003EBut the problem does not stop here. The blade velocity increases along the length of the blade. So the relative wind speed becomes more inclined towards the tip. To make sure that the relative velocity is aligned at all the cross-sections of the blade a continuous twist is given to the blade from the root to tip.This twist is clearly depicted in Fig.4. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-d5JNmFa2KNA\/VuJM68kEy5I\/AAAAAAAADtg\/jGbz3L0EzMA7Y8xdy5v_iiY8EnlXWeyIQ\/s1600\/blade_twist.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 Wind turbine blades are always twisted as shown \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E\u003C\/p\u003E\u003Ch2\u003EWind Turbine Components\u003C\/h2\u003E\u003Cp\u003ENow we will see different components and accessories used in a wind turbine to enhance its performance. \u003Ch3\u003EGearbox - Increase the rotational speed\u003C\/h3\u003E\u003Cp\u003ENoise produced by the wind turbines is a huge issue around the globe. Higher the speed of the rotor more the noise is. Due to this reason wind turbine rotor is always designed to turn at very low RPM. However, such a low speed rotation cannot be directly coupled to a generator, it will not produce any meaningful electricity frequency. So, before connecting to the generator, the speed is increased in a gearbox. The gearbox uses a planetary gear set arrangement to achieve the high speed ratio. Usually the speed \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-iUw8de3wnJk\/VuFWlqcT6SI\/AAAAAAAADso\/mjd5F6h4Dws\/s1600\/gear_box.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 A gearbox based on planetary gear arrangement is used to achieve the high speed ratio\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E\u003Ch3\u003EFunction of Brake\u003C\/h3\u003E \u003Cp\u003EToo much of wind speed may be catastrophic for a wind turbine. High wind speed will make the blade speed at excessive speed, much above the designed limit and induce a huge centrifugal force. This will eventually lead to blade failure. To arrest the blade rotation during excessively windy condition a brake is used in the nacelle. Usually a maximum limit of 80 km\/hr is set for the cut-off speed.\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-zaQj2GJmyCc\/VuJKeYK8kDI\/AAAAAAAADtU\/41NpIJo2_LcF81mW7jnSAa07qYXlUidvw\/s1600\/Windturbine_parts.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 Different parts of wind turbine are marked here \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E \u003Ch3\u003EStep-up Transformer\u003C\/h3\u003E\u003Cp\u003EConsequently, the electricity that is produced is transferred through the cables towards the base, where a step-up transformer is situated. High voltage is always easy to transmit due to the low transmission loss it produces. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-ScSYYQpyfXs\/VuJRrXBx0GI\/AAAAAAAADts\/MGnVivVyt7kE-eou7-pBDB-5yjkNvyFbw\/s1600\/step_up_transformer.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.7 A step-up transformer is usually situated at the base of the wind turbine.\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003C\/p\u003E\u003Ch2\u003EKeep it Aligned with the Wind \u003C\/h2\u003E   \u003Cp\u003ETo extract maximum energy from the wind, it is always needed to keep it aligned with the wind. In this section we will see how the wind turbine is aligned with the wind both in nacelle and blade level. \u003Ch3\u003EThe Yaw Mechanism \u003C\/h3\u003E  \u003Cp\u003EThe blades should face the wind normally for maximum power extraction. But, the wind direction can change at any time. A velocity sensor fitted on the top of the nacelle measures the wind speed and direction. The deviation in the wind’s direction is sent to an electronic controller, which in turn sends an appropriate signal to the yawing mechanism to correct the error. You can see how the yaw motors turn the nacelle. Thus, the wind turbine will always be aligned with the wind direction. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-6h2RMX9EhLU\/VuJIDcNDnPI\/AAAAAAAADtI\/gbkw_nEDzWcNLEJnmegJS2j3ncmyPIxeQ\/s1600\/Yaw_Mechanism.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.8 Yaw motors rotate the nacelle to keep it aligned with the wind \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E\u003Ch3\u003EOptimizing the Blade Orientation\u003C\/h3\u003E\u003Cp\u003EAccording to the wind speed, the relative velocity angle of the wind also changes. This is clearly depicted in Fig.9. You can see that with the increase in wind speed, relative wind velocity becomes more normal to the blade. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-zTO7I7xayUM\/VuFWmCFS8mI\/AAAAAAAADsw\/FugTEm1zXfw\/s1600\/relative_velocity_change.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.9 A blade tilting mechanism helps to keep the blade aligned with the changing wind relative velocity \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E A blade tilting mechanism tilts the blades and guarantees a proper alignment of the blades with the relative velocity. Fig.10 shows details of how the blade are tilted. Thus the blades are always at the optimum angle of attack with the relative wind flow. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-F8cxnR72BDQ\/VuFWkTFpaiI\/AAAAAAAADr4\/BAywAgMtV50\/s1600\/Blade_tilting_mechanism.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.10 More details of blade tilting mechanism \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003C\/p\u003E\u003Ch2\u003EWind Turbine Efficiency\u003C\/h2\u003E\u003Cp\u003EEfficiency of a wind turbine is a really interesting topic. Historically many crazy attempts have been made to extract the maximum energy from the wind. But all of these attends were no fruitful. In this section we will see why a wind turbine cannot achieve 100% efficiency in a logical way. \u003Ch3\u003ELet's Measure the Wind Speed\u003C\/h3\u003E\u003Cp\u003E To gain a good insight into wind turbine efficiency, assume that you are measuring wind speed at upstream and downstream of a wind turbine. You can note that the wind speed at the downstream is much smaller than the upstream. This is because the blades absorb some kinetic energy from the wind. The same amount of energy is converted as mechanical power of the wind turbine.\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-BikiSS2A6Uc\/VuFWkJoJvDI\/AAAAAAAADro\/QqM_e0VFIS4\/s1600\/velocity_measurement_wind_turbine.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.11 If you measure the wind speed across the wind turbine, you can note that wind speed at the upstream is less than the downstream \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E\u003Ch3\u003EIs Zero downstream speed possible ?\u003C\/h3\u003E\u003Cp\u003EIt is interesting to note that a wind turbine absorbs 100% of the available kinetic energy, only if the downstream wind speed becomes zero. However, zero wind speed at downstream is a physically impossible condition.  This cartoon animation clearly depicts this fact. Zero downstream speed simply means that the whole flow is stuck.\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/2.bp.blogspot.com\/-U9LdPJh3yg0\/VuFWk7vjbZI\/AAAAAAAADsI\/tyWj6X3pwfo\/s1600\/zero_velocity_situation.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.12 Zero wind speed means the whole flow is stuck \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EThis leads to an interesting conundrum. You will get maximum energy extraction only when the exit speed is zero, but such a condition means there is no flow through wind turbine. It is clear that wind turbine efficiency is zero, when the outlet wind speed is same as the inlet wind speed. This means there exists an optimum value of outlet wind speed between zero and inlet velocity where the efficiency is maximum. \u003C\/p\u003E \u003Ch3\u003EBetz's Limit\u003C\/h3\u003E\u003Cp\u003EThis physical reality of the flow demands a certain amount of exit wind speed. That means that there is a theoretical maximum efficiency a wind turbine can achieve. This limit is known as Betz’s limit. One can theoretically evaluate value of this maximum efficiency value of a Horizontal Axis Wind Turbine. The value turns out to be 59.3 %.  Essentially, it means that no wind turbine in the world can ever cross the efficiency limit of 59.3 %. You can check for the derivation of Betz's limit in a separate article. However Betz's limit is possible only when the turbine has an infinite number of blades and and the blades are rotating at a very high speed. About 40% of mechanical efficiency is practically possible in today's wind turbines. \u003C\/p\u003E\u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2466370752380359853"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2466370752380359853"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2016\/03\/Wind-turbine-working-design-details.html","title":"Working and Design detials of Wind Turbines"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/img.youtube.com\/vi\/qSWm_nprfqE\/default.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-4742282326812889662"},"published":{"$t":"2015-10-24T02:52:00.001-07:00"},"updated":{"$t":"2016-04-28T01:18:03.392-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Manufacturing"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Understanding Cutting Tool Geometry"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EThe selection of proper cutting tool geometry is of the utmost importance when doing an effective cutting. In this video, we will provide a clear explanation of the cutting process and tool geometry related to single point cutting tool. \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/bUrp8JMRwx4\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003EA detailed webpage version of the video is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E \u003Ch2\u003E The Basic Cutting Operation\u003C\/h2\u003E\u003Cp\u003ETo remove a metal chip from a work piece, you have to cut along at least 2 surfaces. Cutting along just one surface will not guarantee chip removal. This is clearly shown in the figure below. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/4.bp.blogspot.com\/-wOdeJrSqlzI\/VimEsO81mSI\/AAAAAAAADn8\/5izeewMLTgM\/s1600\/basic_cutting_principle.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 To remove a piece of metal from the work piece you have cut through 2 surfaces \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E    For this purpose, cutting tools are provided with 2 cutting edges, a main cutting edge and an auxiliary cutting edge. The main cutting edge cuts the main portion of the chip, while the auxiliary cutting edge cuts the second surface and removes the material. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-IDzah24g5kM\/VimFZS2irwI\/AAAAAAAADok\/u-YKyyc2fU0\/s1600\/main_auxiliary_cutting_edges.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 A close-up view of main and auxiliary cutting edges \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E    \u003C\/p\u003E\u003Ch2\u003ESingle Point Cutting Tool –  Tool Geometry Details\u003C\/h2\u003E\u003Cp\u003EThe single point cutting tool has many geometrical parameters to make the cutting process more smooth and efficient.  These geometrical parameters also help to enhance the tool life by a great extent. All these details are discussed in this session. \u003C\/p\u003E\u003Ch3\u003ENose Radius\u003C\/h3\u003E\u003Cp\u003EYou can see the smooth corner between the main and auxiliary cutting edges; this corner is known as the nose of the tool. The radius of the nose greatly affects the surface finish of the operation and the strength of the tool.  Sharp nose always produces scratches on the work piece. A blunt nose as shown in the figure eliminates these scratches and gives a good surface finish. Moreover the risk of nose breakage is greatly reduced in a tool with an appropriate nose radius. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/2.bp.blogspot.com\/-FXacgIH4L_I\/VimEs0Rm7dI\/AAAAAAAADoA\/FoSM5mBRYy4\/s1600\/nose_and_rake_angle.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 Nose, Rake angle and relief angle make the cutting operation more efficient \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E    \u003C\/p\u003E\u003Ch3\u003ERake Angle\u003C\/h3\u003E\u003Cp\u003EMaterial removal by the main cutting edge is easier when the material’s flowing surface is at an angle, as shown. This angle is known as the rake angle of the tool, more specifically as the back rake angle. The back rake angle greatly affects the chip thickness and the force of the cutting. The rake angle can be positive, zero or negative . A positive rake angle greatly reduces the cutting force . Due to this reason most of the cutting operations are done with a positive rake angle.\u003C\/p\u003E\u003Ch3\u003ERelief Angle\u003C\/h3\u003E\u003Cp\u003ETo avoid the rubbing of the cutting tool with the work piece, a relief angle is provided as shown. The relief angle greatly reduces the tool wear. Please remember that the relief angle has to be positive always. \u003C\/p\u003E\u003Ch3\u003ESide Rake and Relief Angle\u003C\/h3\u003E\u003Cp\u003ESimilar rake and relief angles are also given to the auxiliary cutting edge. To get a better view of the angles a cross-sectional shape is shown in the figure below.\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/4.bp.blogspot.com\/-o4cGt1P_TFk\/VimGfnZ9BpI\/AAAAAAAADow\/BIFG5B0VM_E\/s1600\/side_rake_relief_angles.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 Auxiliary cutting edge is also provided with rake and relief angles \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E   \u003C\/p\u003E\u003Ch3\u003EEnd and Side Cutting Edge Angle\u003C\/h3\u003E\u003Cp\u003ENow, let’s have a look at the tool’s initial position. You can see that the cutting edges form angles, as shown. They are called end and side cutting edge angles.\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-1dJh29b8Khw\/VimEszdiKtI\/AAAAAAAADoE\/hwkK61ZHufU\/s1600\/side_end_cutting_edge_angles.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 A view of side and end cutting edge angles \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  \u003C\/p\u003E\u003Ch2\u003EThe Tool  Signature\u003C\/h2\u003E\u003Cp\u003EThese 7 parameters together, completely define the geometry of a tool. These 7 parameters together known as the signature of a tool. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-JDI-zLbI4mg\/VimEsNT858I\/AAAAAAAADn0\/pTASgQ4suZg\/s1600\/Tool_nomenclature.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 The 7 parameters discussed so far is known as tool signature \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E    There are different international standards available to represent the the tool signature. However all those standards are interchangeable.\u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/4742282326812889662"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/4742282326812889662"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2015\/10\/single-point-cutting-tool.html","title":"Understanding Cutting Tool Geometry"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/img.youtube.com\/vi\/bUrp8JMRwx4\/default.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-7104603657198055370"},"published":{"$t":"2015-08-24T22:45:00.000-07:00"},"updated":{"$t":"2016-04-28T01:18:27.266-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Automobile"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Machine Design"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Manual Transmission, How it works ?"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EManual transmission, or simply a gearbox, has been serving automobiles well for many decades. Even today it’s the most popular form of transmission. Globally manual transmission accounts for 52% of market share as per 2013 data. In this video, we’ll give a conceptual introduction on the workings of an actual manual transmission with a reverse gear.  \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/wCu9W9xNwtI\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003EA detailed webpage version of the video is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E   \u003Ch2\u003EWhy the Transmission is Required?\u003C\/h2\u003E\u003Cp\u003EThe basic question, is why transmission is required in an automobile?  The power generated by the engine flows through the transmission before it reaches the drive wheels.The basic function of the transmission is to control the speed and torque available to the drive wheels for different driving conditions.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-cWVnefU6xVc\/Vdwwze3VBPI\/AAAAAAAADl4\/7GiQwLtraI8\/s1600\/drive_train_automobile.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 Power flow in an automobile; the power from engine to drive wheels is transferred through a drive train \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E   For example, if you want to climb a hill, you need more torque. By reducing the speed at the transmission, we will be able to achieve higher torque for the same power input. This is simply conservation of energy. Power transmission through a shaft is torque times angular velocity of the shaft. When you reduce the speed of the shaft, it will automatically result in increase in the torque transmission. Conversely, if the torque demand is low , we can increase the transmission speed. These 2 cases are depicted in Fig.2. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-lok3KAwSRos\/VdAaRzzXwfI\/AAAAAAAADi0\/jav35buRkc0\/s1600\/transmission_use.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 During a climb the wheels need more torque; during descent the reverse is the case\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003Ch2\u003EThe Basic Working Principle \u003C\/h2\u003E\u003Cp\u003ENow let’s look at its inner workings. Manual transmissions work on the simple principle of gear ratio. As shown in Fig.3 a different output speed can be achieved by meshing gears of different size. The speed ratio is given by the simple equation shown in the figure (N represents speed, T represents number of teeth). \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-RLhrqywZaRI\/VdppLlFYZiI\/AAAAAAAADlo\/eDmDgmWxyyg\/s1600\/Basic_Principle_Gear_ratio.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 The basic principle of a gear pair \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E  \u003Ch2\u003ESliding Mesh Transmission\u003C\/h2\u003E\u003Cp\u003ESliding mesh is the one of the earlier type of manual transmission technology, and the one which is easiest to understand. The most basic slidngmesh transmission mechanism is shown in the Fig.4. Here the input and output shafts are connected through a counter shaft. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-NHpPSSxIaJc\/VdAaRUjONUI\/AAAAAAAADik\/IqUWi3Je_YI\/s1600\/sliding_mesh_transmission_operation.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 First and second gear in a sliding mesh transmission; the red line represents the power flow  \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EThis mechanism can operate under 2 different configurations. In the firs configuration, the output shaft will turn at a slower speed than the input. Just by sliding output gear and connecting the output shaft with the input will result in the second configuration. It is clear that, here the input and out will turn at the same speed. Direction of the power flow is represented as red dotted lines in the Fig.4.   \u003Cp\u003E A 3-speed mechanism will look as shown in the Fig.5. For the gear meshing shown in the figure, the output shaft will rotate at its slowest speed (1\u003Csup\u003Est\u003C\/sup\u003E Gear).It is clear that just by sliding the gears we can achieve different transmission ratios, such as 2\u003Csup\u003End\u003C\/sup\u003E and 3\u003Csup\u003Erd\u003C\/sup\u003E gears.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-8rfOXRwAt4c\/VdA2zMfDFZI\/AAAAAAAADjg\/rv1rrqu3bfc\/s1600\/Three_Speed_Sliding_Mesh.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 Three speed sliding mesh transmission: first gear is shown in the figure \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E   \u003Cp\u003EThe sliding mesh transmission is good for controlling the speed, but they have an inherent disadvantage.  It’s quite tricky to slide from one gear and engage with another gear. A technology known as double clutching should be used for achieving a smooth slide of gears. The driver should possess a good skill to do an effective double clutching. Maintenance associated with the double clutch transmissions are quite frequent too.\u003C\/p\u003E\u003C\/p\u003E   \u003Ch2\u003ESolving the Sliding Problem – Synchromesh Transmission\u003C\/h2\u003E\u003Cp\u003E\u003Cp\u003EThe synchro mesh transmission permanently solves this problem. Here the gears are always in mesh, but with a major difference. Here the output gears are loosely connected to the shaft. You can see from Fig.6 that there is a small clearance between the output gears and shaft. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-6zmAxnjX_mY\/VdAxIGzVYTI\/AAAAAAAADjI\/XIlbADqlUTY\/s1600\/synchromesh.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 Synchromesh transmission: Here the gear pairs are always in mesh \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E If we connect only one gear to the shaft at a time, the shaft will have the speed of the connected gear.\u003C\/p\u003E\u003Ch3\u003EUnderstanding the basis using a Hypothetical connector\u003C\/h3\u003E\u003Cp\u003EWe will first use a hypothetical connector to illustrate how different gear ratios work in the sycnhromesh transmission. Later on we will move to the actual technology. With the help of the hypothetical connector, different gear ratios are illustrated in Fig.5. It is interesting to note that in 4th gear the input and output shafts are directly connected. This means the output and input shaft will have the same speed in 4th gear. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-tmRDh4SUpm0\/VdnA0B50ZcI\/AAAAAAAADj4\/a5o_bZjO4CM\/s1600\/Hypothetical_Connector.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.7 First and Fourth gear are illustrated in this figure with help of a hypothetical connector \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EThe art of locking a loosely held gear to the shaft effectively and smoothly lies at the heart of the manual transmission. Let’s see how this is done in actual practice.\u003C\/p\u003E  \u003Ch3\u003ESynchronizer Cone-Teeth Arrangement\u003C\/h3\u003E\u003Cp\u003EFirst of all, the main shaft gears have a synchronizer cone-teeth arrangement as illustrated in Fig.8.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-5swUB5IMv9U\/VdnA0McmC9I\/AAAAAAAADj8\/OT2nilQ1Sv4\/s1600\/Synchronizer_cone_teeth.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.8 Synchronizer cone teeth arrangement of synchromesh transmisson \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E A hub is fixed to the shaft. A sleeve that is free to slide over the hub is also used in this system. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-UnIAp-090X4\/VdnD51rZXjI\/AAAAAAAADkM\/rfsXKixaAMw\/s1600\/Sleeve_Hub.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.9 When the sleeve and synchronizer teeth are engaged the locking action can be achieved \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EIt is clear that, if the sleeve gets connected with the teeth of the synchronizer cone, the gear and shaft will turn together, or the desired locking action will be achieved. But during the gearbox operation, the shaft and gear will be rotating at different speeds. So such a locking action is not an easy task.\u003C\/p\u003E  \u003Ch3\u003EUse of Synchronizer ring\u003C\/h3\u003E\u003Cp\u003EA synchronizer ring helps to match the speed of the gear with that of the shaft. The synchronizer ring is capable of rotating along with the hub, but is free to slide axially. Before moving the sleeve, the clutch pedal is pressed. This way power flow to the gear is discontinued.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-wS0Wc9_Mygs\/VdnFe49XtyI\/AAAAAAAADkY\/95Cvg47zY5g\/s1600\/Synchronizer_Ring.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.10 A synchronizer cone is placed between a hub and synchronzier cone \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003EWhen we move the sleeve, the sleeve will press the synchronizer ring against the cone. Due to the high frictional force between the synchronizer ring and cone, the speed of the gear will become the same as the shaft. At this time, the sleeve can be slid in further, and it will get locked with the gear. Thus, the gear gets locked with the shaft in an efficient and smooth way. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-CahbbUu1xQI\/VdnIxmlAWYI\/AAAAAAAADk0\/iLGkgx_vqaA\/s1600\/synchromesh_operation.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.11 Movement of sleeve brings the synchronizer teeth and sleeve to the speed, after that the locking is achieved \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E   \u003Ch2\u003EDifferent Gear Ratios \u003C\/h2\u003E\u003Cp\u003EWhat we have seen in last section was  the technology behind the 2\u003Csup\u003End\u003C\/sup\u003E  gear. In the same way the other gear ratios are also achieved. The details are described in this session.    \u003Ch3\u003EUnder Drive – 1\u003Csup\u003Est\u003C\/sup\u003E, 2\u003Csup\u003End\u003C\/sup\u003E and 3\u003Csup\u003Erd\u003C\/sup\u003E\u003C\/h3\u003E\u003Cp\u003EIn under drive the output shaft turns at a lower speed than the input.  For the manual transmission technology we are explaining 1\u003Csup\u003Est\u003C\/sup\u003E , 2\u003Csup\u003End\u003C\/sup\u003E and 3\u003Csup\u003Erd\u003C\/sup\u003E gear ratios fall under the under drive category. The following figure depicts the sleeve motion required for 1st and 3rd gear. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-SEqzty0X9tc\/VdnHQgmUUrI\/AAAAAAAADkk\/EE4x0G2FoaU\/s1600\/1st_3rd_Gear.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.12 The first and third gear of a manual transmission \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E\u003Ch3\u003EDirect Drive\u003C\/h3\u003E\u003Cp\u003EAs the name suggests in direct drive, the output and input shafts turn at the speed. For this purpose the output and input shafts are directly coupled using the synchronizer cone-sleeve mechanism. The hub is fixed to the output shaft, when the sleeve gets connected with the synchronizer teeth of the input shaft, they get coupled together. During the direct drive, the sleeve at the third gear position (2nd part Fig.12) should move to left side.\u003C\/p\u003E\u003Ch3\u003EOver Drive\u003C\/h3\u003E\u003Cp\u003EA 5th gear is used to turn the output shaft at a higher speed than the input shaft. You can note here that unlike the other gear pairs, in 5th gear the output shaft gear is smaller than the counter shaft gear. This generates the overdrive scenario. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-LLUDQzO9YpU\/VdnKkSCg32I\/AAAAAAAADlA\/QtaSHeNSrp0\/s1600\/Over_drive.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.13 The arrangement of 5th gear \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E You can note more difference in the 5th drive configuration, the output gear is fixed to the shaft and the counter shaft gear is loosely connected. As a result synchroizer ring – sleeve mechanism is arranged on the counter shaft. The sole purpose of such an arrangement is to accommodate the reverse gear mechanism. We will see that in next session. \u003C\/p\u003E\u003Cp\u003EThe sleeve motion is controlled by a shift stick . You can also  see the mechanism used for controlling the sleeve with the shift stick. You can note that using this mechanism, not more than one sleeve will be engaged with the output gears. That is important, since engaging 2 sleeves at a time will lead to an impossible turning condition. \u003C\/p\u003E\u003Ch3\u003EThe Reverse Gear\u003C\/h3\u003E\u003Cp\u003ENow let’s see how the reverse gear works? The reverse gear uses a 3-gear arrangement, as shown. Out of those, one is the idle gear. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-lozFxoQJ4mc\/VdnZD6KAZeI\/AAAAAAAADlU\/17PeizlLiWY\/s1600\/Reverse_Gear.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.14 The three gear arrangement of a reverse gear \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E It is clear that addition of one more gear will turn the output shaft gear in the reverse direction. For engaging the reverse gear the idle gear is pushed and connected to the other 2 gears. Thus  the required output shaft rotation in the reverse direction can be achieved. Please note here that the reverse gear does not have a synchronizer ring mechanism. This means that, the gearbox rotation has to stop completely before applying the reverse gear. \u003C\/p\u003E\u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-mgGikPzE4es\/VdnZDoSLKfI\/AAAAAAAADlQ\/R5xcplEEzJw\/s1600\/Reverse_Working.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.15 The idle gear is pushed and connected with the other 2 gears to achieve the reverse operation \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003Cp\u003EYou might have noticed that in reverse gear, your vehicle moves in a very low speed. As you can see from the figure the three gear arrangement gives speed reduction in 2 stages. This results in very low output speed (high torque). Generally the reverse has a gear ratio of 4:1 (input speed : output speed). \u003C\/p\u003E   \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7104603657198055370"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7104603657198055370"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2015\/08\/Manual-Transmission-Working.html","title":"Manual Transmission, How it works ?"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/img.youtube.com\/vi\/wCu9W9xNwtI\/default.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-7188373855658821700"},"published":{"$t":"2014-11-19T03:33:00.000-08:00"},"updated":{"$t":"2016-04-28T01:19:35.261-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Automobile"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Machine Design"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Torsen Differential, How it works ?"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003ETorsen is a trade mark of the JTEKT Corporation.  The Torsen differential has many patented components and,  is the most unique and ingenious method of providing differential action while overcoming the traction difference problem. This article gives a logical introduction to the working of Torsen differential.\u003C\/p\u003E  \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"720\" height=\"405\" src=\"\/\/www.youtube.com\/embed\/JEiSTzK-A2A\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003E\u003Cp\u003EA detailed webpage version of the video is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003EThe internal components\u003C\/h2\u003E\u003Cp\u003EThe internal components of a Torsen are quite different from that of a conventional differential. An exploded view of the Torsen is given in Fig.1.   \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-Xx4eHtrjh9A\/VJfybu2On3I\/AAAAAAAADV4\/iRkdhsDuG7I\/s1600\/Torsen_componets.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 An exploded view of Torsen differential \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  At the heart of the system lies a specially shaped gear pair assembly. Let’s see the cross sectional shape of these gears at the mating point. As can be seen, one gear is a spur gear, and the other one is a worm gear.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-UPbUXETyMnw\/VJk3DZLU8TI\/AAAAAAAADWI\/CG_ygbOzhbc\/s1600\/Worm_gear_Worm_wheel.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 A worm gear-worm wheel mesh lies at the heart of the Toresn; Cross sectional shape of the figure is shown in the second part  \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  A Torsen works on the simple principle of worm gear- worm wheel; that is a spinning worm gear can rotate the wheel, but the rotating wheel cannot spin the worm gear.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-yLoMYbRSHJY\/VJlAgSxg_AI\/AAAAAAAADWY\/ETau-jdt5wY\/s1600\/Principle_Torsen.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 The worm gear- worm wheel principle lies at the heart of the Torsen operation \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E Throughout this discussion, just keep this principle in mind.  A pair of such worm wheels are fitted with the case, so the engine power received by the case is transferred to the worm wheels.  Each end of the wheels is fitted with a spur gear. As a result, a simplified Torsen differential will look as shown in the Fig.4.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-a1TFyHpiWXk\/VJlDYJe2vFI\/AAAAAAAADWs\/o40w1cJ3yK8\/s1600\/Basic%2BComponents.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 The complete Torsen differential\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003ENow we will go through different driving scenarios and understand how the Torsen manages to operate the vehicle well.\u003C\/p\u003E\u003Ch2\u003EThe Vehicle Moves Straight\u003C\/h2\u003E  \u003Cp\u003EWhen the vehicle moves straight, the worm wheels will push and turn the worm gears. So both the drive wheels will rotate at the same speed.  Please note here that, in this condition the worm wheels do not spin on its own axis.  In this condition, the whole mechanism moves as a single solid unit.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/1.bp.blogspot.com\/-GNsvkKPKlKU\/VJlXKjxHiwI\/AAAAAAAADW8\/DAfUJEZRtO0\/s1600\/Vehicle_moves_straight.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 When the vehicle moves straight, worm wheels just push and turn the worm gears at the same speeds. \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003Ch2\u003EThe vehicle takes a right turn\u003C\/h2\u003E\u003Cp\u003EWhen the vehicle is negotiating a right turn, the left wheel needs to rotate at a higher speed than the right wheel. This fact is clear from the Fig.6. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-P6vRUp4Snms\/VK-xSBJdauI\/AAAAAAAADXs\/TaSeFEKJavA\/s1600\/Right_Turn.png\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 During a right turn the left wheel has to travel more distance \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  This speed differential is perfectly supported in a Torsen. Please note that the worm wheel is subjected to relative motion not the absolute motion. The worm wheel is fitted between the case and worm gear, so the relative motion between the case and worm gear is what makes the worm gear turn.\u003C\/p\u003E \u003Cp\u003EThe worm gear of the faster left axle will make the corresponding worm wheel spin on its own axis. On the other side, relative to the case the slow right axle is turning in the opposite direction; thus the right worm wheel will spin in the opposite direction. The meshing spur gears at the ends of worm wheel will make sure that, the worm wheels are spinning at the same speed. Thus it guarantees a perfect differential action. Perfect differential action implies equal amount of speed loss and speed gain to the right and left wheels. With the perfect differential the vehiclce will be able to negotiate a smooth turn.   \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-TI3DAajiUWQ\/VK-wbYZqCzI\/AAAAAAAADXg\/txJoaW8-vUk\/s1600\/right-turn-Torsen.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.7 The right worm wheel will spin opposite to the right worm wheel; this is due to the opposite relative motion left worm wheel is experiencing  \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003EWhile taking a left turn the worm wheels will spin in an exact opposite way to that shown in Fig.7.\u003C\/p\u003E\u003Ch2\u003EOvercoming the Traction difference problem\u003C\/h2\u003E  \u003Cp\u003ENow let’s try to understand how the Torsen overcomes the drive wheel traction difference problem.  As you might be aware, when your vehicle encounters a situation as shown, the slippery wheel starts to spin very rapidly and will draw the majority of the engine’s power.  As a result, the vehicle will get stuck. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/3.bp.blogspot.com\/-e-GyAKG2SIc\/VK-x7WmmN7I\/AAAAAAAADX0\/3grwVfkt0wM\/s1600\/traction_difference_problem.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.8 A typical traction difference problem a vehicle is experiencing \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  But, if a Torsen differential is used in this case, as soon as the slippery wheel starts to spin excessively, the speed change will be transferred to the corresponding worm wheel.  The right worm wheel transfers the speed change to the left worm wheel, since they are connected through spur gears.  Here comes the tricky part! The left side worm wheel will not be able to turn the corresponding worm gear, because, as we said, a worm wheel cannot drive a worm gear!  As a result, the whole mechanism gets locked, and the left and right wheels turn together.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"http:\/\/1.bp.blogspot.com\/-ppcL2vQ4SUc\/VK-yJ9eCEBI\/AAAAAAAADX8\/YJ_K2WTYtsQ\/s1600\/Torsen_Locking_action.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.9 The excessive speed of slipping wheel make the system locked due to the 'basic principle of worm gear-worm wheel' \u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E This allows a large amount of power to be transferred to the high-traction wheel, and the vehicle can thereby overcome the traction difference problem. To carry the load 2 more worm wheel pairs are added.\u003C\/p\u003E  \u003Ch2\u003EPros and Cons of Torsen\u003C\/h2\u003E\u003Cp\u003EIf you are familiar with the other common technologies used to overcome the traction difference problem, you might have noticed a great advantage of the Torsen.  While the other technologies allow the drive wheel to slip for a limited amount of time before it gets locked, in Torsen the locking action is instantaneous. That means as soon as the vehicle encounters a traction difference track the wheels will get locked. They are also compact compared to their counter parts.\u003C\/p\u003E\u003Cp\u003EFollowing are the some disadvantages of the Toresn type (T1) explained here. \u003Cul\u003E\u003Cli\u003ENoisy\u003C\/li\u003E\u003Cli\u003ECostly\u003C\/li\u003E\u003Cli\u003EMore difficult to assemble\u003C\/li\u003E\u003C\/ul\u003E \u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7188373855658821700"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7188373855658821700"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2014\/11\/Torsen-Differential.html","title":"Torsen Differential, How it works ?"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"http:\/\/3.bp.blogspot.com\/-Xx4eHtrjh9A\/VJfybu2On3I\/AAAAAAAADV4\/iRkdhsDuG7I\/s72-c\/Torsen_componets.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-8219067920659538249"},"published":{"$t":"2014-05-21T19:29:00.001-07:00"},"updated":{"$t":"2016-04-28T01:22:36.998-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Automobile"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Machine Design"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Working of a Limited Slip Differential "},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003ELimited slip differentials \u003Ci\u003E(LSD)\u003C\/i\u003E are used in automobile to overcome the traction difference problem of drive wheels. In this article working of \u003Ci\u003ELSD\u003C\/i\u003E is explained in a logical manner.\u003C\/p\u003E\u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"\/\/www.youtube.com\/embed\/WeLm7wHvdxQ\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003E\u003C\/div\u003EDetailed webpage version of the video is given below. \u003Chr\u003E\u003Cbr\u003E \u003Ch2\u003EProblem with the Standard Differential\u003C\/h2\u003E\u003Cp\u003EConsider a situation where a vehicle fitted with a standard differential moves straight, and one drive wheel is on a surface with good traction and the other wheel is on a slippery track. In a standard differential the left and right axle rotations are completely independent.  Since one wheel is on a slippery track, the standard differential will make that wheel spin in excessive speed, while the good traction wheel will remain almost dead. This means high power supply to the slippery wheel and low power flow to the good traction wheel. So the vehicle won’t be able to move. \u003C\/p\u003E \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/1.bp.blogspot.com\/-CIho-qj6660\/U3yKuMvd6rI\/AAAAAAAADEo\/FJSlPwuRzR4\/s1600\/traction+difference+problem.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 In a standard differential power from the engine is transferred to the wheel with low traction\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E   \u003Cp\u003EOne way to overcome this problem is to limit the independency or relative motion between the left and right axles. \u003Ci\u003ELimited slip differentials\u003C\/i\u003E are introduced for this purpose.  One of the most commonly used LSD technology is \u003Ci\u003Eclutch-pack based\u003C\/i\u003E.\u003C\/p\u003E\u003Ch2\u003EConstructional Features of LSD\u003C\/h2\u003E\u003Cp\u003EFirst we will go through constructional features of LSD.\u003C\/p\u003E   \u003Cp\u003EThe basic components of a standard differential are shown below. It has got pinion gear, ring gear, case, spider gears and side gears.   \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-hXj9lVxYwew\/U3yKnc25ZYI\/AAAAAAAADD0\/BKeLzDDYwH0\/s1600\/differential+components.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 The basic components of a standard differential\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E To understand working of a standard differential please check \u003Ca href=\"http:\/\/www.learnengineering.org\/2014\/05\/working-of-differential.html\" target=\"_blank\"\u003E\u003Cfont color=\"blue\"\u003Ethis link\u003C\/font\u003E\u003C\/a\u003E . Apart from its basic components a Limited slip differential has got a series of friction and steel plates packed between the side gear and the casing. Friction discs are having internal teeth and they are locked with the splines of the side gear. So the friction discs and the side gear will always move together.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/2.bp.blogspot.com\/-LBJqwJXcfTA\/U3yKnQlQV7I\/AAAAAAAADD8\/sqRZE207ke4\/s1600\/LSD_friction_steel+plates.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 It is clear from the figure that steel plates are locked with the case and friction disc with the side gear\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E \u003Cp\u003E Steels plates are having external tabs and are made to fit in the case groove. So they can rotate with the case. \u003C\/p\u003E\u003Cp\u003E If any of the clutch pack assembly is well pressed, the frictional force within them will make it move as a single solid unit. Since steel plates are locked with the case and friction discs with the side gear, in a well pressed clutch pack casing and the clutch pack will move together. Or motion from the casing is directly passed to the corresponding axle.\u003C\/p\u003E    \u003Cp\u003E Space between the side gears is fitted with a pre-load spring. Pre load spring will always give a thrust force and will press clutch pack together. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-3HXZfVOYbz8\/U3yKqzNYYyI\/AAAAAAAADEQ\/YxGwrBYFd70\/s1600\/pre-load+spring+LSD.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 Pre-load spring in an LSD will always give a thrust force; The blue arrow represents thrust force\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003C\/p\u003E \u003Ch2\u003ESeparating action of Bevel gears\u003C\/h2\u003E\u003Cp\u003EYou can note that spider and side gear are bevel gears. It has got one specialty.  When torque is transmitted through a bevel gear system axial forces are also induced apart from the tangential force. The axial force tries to separate out the gears. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-iSqHz8ui4nI\/U3yKnLMm_NI\/AAAAAAAADDw\/e6dfXAMldlI\/s1600\/bevel+gear+action.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 During power transmission through a bevel gear system axial forces are also induced\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E You can note that side gear and axle are 2 separate units. The side gear has got a small allowance for axial movement. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/4.bp.blogspot.com\/-O2dVLF-5HbQ\/U3yKte0h5OI\/AAAAAAAADEg\/wlDFxT6JuA8\/s1600\/side_spider_gear+axle.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 Side gear and axle are two separate units as shown; So the side gear can have small axial movement\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  So during high torque transmission through spider-side gear arrangement, a high separating thrust force is also transmitted to the clutch pack.  This force presses and locks the clutch pack assembly against wall of the casing.\u003C\/p\u003E   \u003Ch2\u003EWorking of Limited Slip Differential\u003C\/h2\u003E\u003Cp\u003ENow back to the initial problem.  Since one wheel is on a high traction surface, the torque transmitted to it will be higher. So the thrust force developed due to the bevel gear separation action also will be high at that side. Thus clutch pack at high traction wheel side will be pressed firmly and clutch pack will be locked.  So power from the differential casing will flow directly to high traction axle via clutch pack assembly.   \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-Ixfu9l7Jamg\/U3yKqMPeMfI\/AAAAAAAADEI\/d7ahqARbhqc\/s1600\/high+traction+power+flow.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.7 Thrust force induced due to the bevel gear separation action is high for the high traction wheel\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  On the other hand clutch pack on the low traction wheel side is not engaged yet, so power flow will be limited to that side. So the vehicle will be able to overcome the traction difference problem.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-5HXQfWs21w0\/U3yKrxjgRDI\/AAAAAAAADEY\/lNtdm0eXRC0\/s1600\/right_clutch.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.8 Low thrust force at low traction wheel will allow steel plate and friction disc to slip\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E  \u003Cp\u003EHowever while taking a turn the LSD can act like a normal differential.  In this case thrust force developed due to bevel gear separation action won’t be that high. So the plates in clutch pack will easily overcome frictional resistance and will be able to slip against each other. Thus the right and left wheel can have different speed just like an open differential.\u003C\/p\u003E  \u003Cp\u003EFollowing are the other commonly used technologies used to overcome the drive wheel traction difference problem. \u003Cul\u003E\u003Cli\u003EClutch pack - Pressure disk type\u003C\/li\u003E\u003Cli\u003ETorsen\u003Csup\u003E®\u003C\/sup\u003E\u003C\/li\u003E\u003Cli\u003ECone Differential\u003C\/li\u003E\u003Cli\u003EHydraulic Locking Type\u003C\/li\u003E\u003C\/ul\u003E \u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/8219067920659538249"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/8219067920659538249"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2014\/05\/limited-slip-differential.html","title":"Working of a Limited Slip Differential "}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/1.bp.blogspot.com\/-CIho-qj6660\/U3yKuMvd6rI\/AAAAAAAADEo\/FJSlPwuRzR4\/s72-c\/traction+difference+problem.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-2921013596763401544"},"published":{"$t":"2014-05-06T22:35:00.000-07:00"},"updated":{"$t":"2016-04-28T01:23:05.749-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Automobile"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Machine Design"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"How does a Differential work ?"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EThe differential is an integral part of all four wheelers. Differential technology was invented centuries ago and is considered to be one of the most ingenious inventions human thinking has ever produced. In this video, we will learn, in a logical manner, why a differential is needed in an automobile and its inner workings.   \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"\/\/www.youtube.com\/embed\/SOgoejxzF8c\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003E A detailed webpage version of the video lecture is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003EWhy the Differential gear is used?\u003C\/h2\u003E\u003Cp\u003E Wheels receive power from the engine via a drive shaft. The wheels that receive power and make the vehicle move forward are called the drive wheels. The main function of the differential gear is to allow the drive wheels to turn at different rpms while both receiving power from the engine.\u003C\/p\u003E \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"power flow in automobile\" src=\"https:\/\/3.bp.blogspot.com\/-UTPTV02kUiQ\/U2jHft4BwEI\/AAAAAAAADB8\/2yl7rD-KHks\/s1600\/power_flow_automobile.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.1 Power from the engine is flowed to the wheels via a drive shaft\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003Cp\u003EConsider these wheels, which are negotiating a turn. It is clear that the left wheel has to travel a greater distance compared to the right wheel. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"Wheels taking right turn\" src=\"https:\/\/1.bp.blogspot.com\/-HvWy63-NOj0\/U2jHizBV9GI\/AAAAAAAADC0\/QD_sS9BB5Ew\/s1600\/wheels_taking_turn.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.2 While taking a right turn the left wheel has to travel more distance; this means more speed to left wheel\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  This means that the left wheel has to rotate at a higher speed compared to the right wheel. If these wheels were connected using a solid shaft, the wheels would have to slip to accomplish the turn. This is exactly where a differential comes in handy. The ingenious mechanism in a differential allows the left and right wheels to turn at different rpms, while transferring power to both wheels.\u003C\/p\u003E \u003Ch2\u003EParts of a Differential\u003C\/h2\u003E\u003Cp\u003EWe will now learn how the differential achieves this in a step-by-step manner using the simplest configuration. Power from the engine is transferred to the ring gear through a pinion gear. The ring gear is connected to a spider gear.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"spider and ring gear\" src=\"https:\/\/4.bp.blogspot.com\/-De97CjRCAJY\/U2jHgT-xeqI\/AAAAAAAADCQ\/-B7fF_GTcR4\/s1600\/spider_gear_ring0300.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.3 Motion from the pinion gear is transferred to the spider gear\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E   The spider gear lies at the heart of the differential, and special mention should be made about its rotation. The spider gear is free to make 2 kinds of rotations: one along with the ring gear (\u003Ci\u003Erotation\u003C\/i\u003E) and the second on its own axis (\u003Ci\u003Espin\u003C\/i\u003E). \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"motion of spider gear\" src=\"https:\/\/1.bp.blogspot.com\/-O-WQ0RC8qew\/U2jHgCFcdEI\/AAAAAAAADCI\/gN2sCICx0Bc\/s1600\/spider_gear_motion.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.4 Spider gear is free to make 2 kinds of rotations\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E    The spider gear is meshed with 2 side gears. You can see that both the spider and side gears are bevel gears. Power flow from the drive shaft to the drive wheels follows the following pattern. From the drive shaft power is transferred to the pinion gear first, and since the pinion and ring gear are meshed, power flows to the ring gear. As the spider gear is connected with the ring gear, power flows to it. Finally from the spider gear, power gets transferred to both the side gears.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"the complete differential\" src=\"https:\/\/2.bp.blogspot.com\/-BNORZhRbpwk\/U2jHeCxoEcI\/AAAAAAAADBs\/cVqcOng7Jxw\/s1600\/full_differential.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.5 The basic components of a standard differential\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E \u003Cp\u003E   \u003Ch2\u003EDifferential Operation\u003C\/h2\u003E \u003Cp\u003ENow let’s see how the differential manages to rotate the side gears (drive wheels) at different speeds as demanded by different driving scenarios. \u003Ch3\u003E The vehicle moves straight\u003C\/h3\u003E\u003Cp\u003EIn this case, the spider gear rotates along with the ring gear but does not rotate on its own axis. So the spider gear will push and make both the side gears turn, and both will turn at the same speed. In short, when the vehicle moves straight, the spider-side gear assembly will move as a single solid unit.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"differential when vehicle moves straight\" src=\"https:\/\/3.bp.blogspot.com\/-XNUT6Rc2Njg\/U2jHhfPhYwI\/AAAAAAAADCc\/j7gNxWaGGhc\/s1600\/vehicle_moves_straight.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.6 While the vehicle moves straight, the spider gear does not spin; it pushes and rotate the side gears\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E \u003Ch3\u003EThe vehicle takes a right turn\u003C\/h3\u003E\u003Cp\u003ENow consider the case when the vehicle is taking a right turn. The spider gear plays a pivotal role in this case. Along with the rotation of the ring gear it rotates on its own axis. So, the spider gear is has a combined rotation. The effect of the combined rotation on the side gear is interesting.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"differential when vehicle turns right\" src=\"https:\/\/1.bp.blogspot.com\/-ZMkIP4NCvuM\/VGwl31z9wvI\/AAAAAAAADU4\/rNDBZYpn0m8\/s1600\/Vehicle_takes_right_turn.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.7 To get peripheral velocity at left and right side of spider gear we have to consider both rotation and spin of it\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E When properly meshed, the side gear has to have the same peripheral velocity as the spider gear. Technically speaking, both gears should have the same pitch line velocity. When the spider gear is spinning as well as rotating, peripheral velocity on the left side of spider gear is the sum of the spinning and rotational velocities. But on the right side, it is the difference of the two, since the spin velocity is in the opposite direction on this side. This fact is clearly depicted in Fig.7. This means the left side gear will have higher speed compared to the right side gear. This is the way the differential manages to turn left and right wheels at different speeds.\u003C\/p\u003E  \u003Ch3\u003EThe vehicle takes a left turn\u003C\/h3\u003E\u003Cp\u003EWhile taking a left turn, the right wheel should rotate at a higher speed. By comparing with the previous case, it is clear that, if the spider gear spins in the opposite direction, the right side gear will have a higher speed.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"differential when vehicle turns left\" src=\"https:\/\/1.bp.blogspot.com\/-rG__eoOrTk0\/VGwl35317bI\/AAAAAAAADU8\/AlqKq5a-Nqg\/s1600\/opposite_spider.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.8 While taking left turn the spider gear spins in opposite direction\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003C\/p\u003E \u003Ch2\u003EUse of more Spider gears\u003C\/h2\u003E\u003Cp\u003EIn order to carry a greater load, one more spider gear is usually added. Note that the spider gears should spin in opposite directions to have the proper gear motion. A four-spider-gear arrangement is also used for vehicles with heavy loads. In such cases, the spider gears are connected to ends of a cross bar, and the spider gears are free to spin independently. \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"use of two spider gears\" src=\"https:\/\/2.bp.blogspot.com\/-1wZXr85hWm4\/VGwl31Eje-I\/AAAAAAAADU0\/ZJMjMhETWOs\/s1600\/double_spider_differential.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.9 Double spider gear arrangement is usually used to carry more loads\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E\u003C\/p\u003E\u003Ch2\u003EOther functions of the Differential\u003C\/h2\u003E  \u003Cp\u003EApart from allowing the wheels to rotate at different rpm differential has 2 more functions. First is speed reduction at the pinion-ring gear assembly. This is achieved by using a ring gear which is having almost 4 to 5 times number of teeth as that of the pinion gear. Such huge gear ratio will bring down the speed of the ring gear in the same ratio. Since the power flow at the pinion and ring gear are the same, such a speed reduction will result in a high torque multiplication.\u003C\/p\u003E\u003Cp\u003EYou can also note one specialty of the ring gear, they are hypoid gears. The hypoid gears have  more contact area compared to the other gear pairs and will make sure that the gear operation is smooth.\u003C\/p\u003E \u003Cp\u003EThe other function of the differential is to turn the power flow direction by 90 degree. \u003C\/p\u003E\u003Ch2\u003EDrawback of a Standard Differential\u003C\/h2\u003E\u003Cp\u003EThe differential we have gone through so far is known as \u003Ci\u003Eopen\u003C\/i\u003E or \u003Ci\u003Estandard differential\u003C\/i\u003E.  It is capable of turning the wheels at different rpm, but it has got one major drawback. Consider a situation where one wheel of the vehicle is on a surface with good traction and the other wheel on a slippery track.  \u003Cdiv align=\"center\" \u003E\u003Ctbody\u003E\u003Cimg alt=\"wheels on different traction\" src=\"https:\/\/2.bp.blogspot.com\/-M8ERDoWMVLo\/U2jQtuTVtGI\/AAAAAAAADDM\/AUE9BWX0xxQ\/s1600\/tranction_difference_differential.jpg\" \/\u003E\u003Cp\u003E\u003Ctr\u003E\u003Ctd  style=\"text-align: center;\"\u003E\u003Cfont size=\"1.95\"\u003EFig.10 A standard differential vehicle on different traction surfaces will not be able to move\u003C\/font\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/p\u003E\u003C\/div\u003E  In this case a standard differential will send the majority of the power to the slippery wheel, so the vehicle won’t be able to move.  To overcome this problem, Limited Slip Differentials are introduced. We will learn more about them in a separate article. \u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2921013596763401544"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2921013596763401544"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2014\/05\/working-of-differential.html","title":"How does a Differential work ?"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/3.bp.blogspot.com\/-UTPTV02kUiQ\/U2jHft4BwEI\/AAAAAAAADB8\/2yl7rD-KHks\/s72-c\/power_flow_automobile.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-1449482093192519788"},"published":{"$t":"2014-04-23T18:33:00.000-07:00"},"updated":{"$t":"2016-04-28T01:23:30.986-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Fluid Mechanics"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Wind Power"}],"title":{"type":"text","$t":"Wind Turbine Design"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EPrimary objective in wind turbine design is to maximize the aerodynamic efficiency, or power extracted from the wind. But this objective should be met by well satisfying mechanical strength criteria and economical aspects. In this video we will see impact of number of blades, blade shape, blade length and tower height on wind turbine design.  \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"390\" src=\"http:\/\/www.youtube.com\/embed\/p5k2LhKBSgQ\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003E Check following article to know more on wind turbine design aspects.\u003Chr\u003E\u003Cbr\u003E\u003C\/p\u003E   \u003Ch2\u003EEffect of Number of Blades\u003C\/h2\u003E\u003Cp\u003EAs the number of blades in the wind turbine increases aerodynamic efficiency increases, but in a diminishing manner. When we move from 2 blades to 3 blades design efficiency gain is about 3%. But as we move from 3 blades to 4 blades design, efficiency gain is marginal.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-GX38_emHzmg\/UhwluKZJPeI\/AAAAAAAACqU\/_-SQluv_AyE\/s1600\/effect_of_number_of_blades.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-GX38_emHzmg\/UhwluKZJPeI\/AAAAAAAACqU\/_-SQluv_AyE\/s1600\/effect_of_number_of_blades.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.1 Efficiency gain as number of blades in wind turbine is increased\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  As we increase number of blades, cost of the system increases drastically. Along with that mechanical design of blades also becomes a difficult affair. With more number of blades, blades should be thinner to be aerodynamically efficient. But blades with thinner portion at the root may not withstand bending stress induced due to axial wind load.  So generally wind turbines with 3 blades which can accommodate a thicker root cross-section are used.   \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh5.googleusercontent.com\/-TB0ZTBE_sck\/UhwlzuIKVZI\/AAAAAAAACqc\/uUtHr0FOpvE\/s1600\/thicker_root_blade.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh5.googleusercontent.com\/-TB0ZTBE_sck\/UhwlzuIKVZI\/AAAAAAAACqc\/uUtHr0FOpvE\/s1600\/thicker_root_blade.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.2 Wind turbine blades have got thicker root to withstanad huge bending moment induced\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E\u003Ch2\u003EWind Turbine Blade Design\u003C\/h2\u003E \u003Cp\u003EThe next big factor which is affecting performance of wind turbine is shape and orientation of blade cross section. A moving machine experiences fluid flow at a different velocity than the actual velocity. It is called as relative or apparent velocity. Apparent velocity of flow is difference between actual flow and blade velocity. Absolute velocity of the flow is shown in first figure, while apparent velocity in the second figure. It is clear that apparent velocity of flow is vectorial difference between actual and blade velocity. The vector difference is shown in the first figure at a particular cross section. A rotating blade will experience an apparent velocity of flow.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh3.googleusercontent.com\/-G-RAljsPgx4\/UhwlpNy21BI\/AAAAAAAACqM\/kg6lXDLazbk\/s1600\/absolute_apparent_velocity.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh3.googleusercontent.com\/-G-RAljsPgx4\/UhwlpNy21BI\/AAAAAAAACqM\/kg6lXDLazbk\/s1600\/absolute_apparent_velocity.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.3 Absolute \u0026 apparent velocity of wind  \u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E A close look at wind turbine blade will reveal that, it is having airfoil cross sections from root to tip. The driving force of wind turbine is, lift force generated, when wind flows over such airfoils. Lift force will be perpendicular to apparent velocity. Generally lift force increases with angle of attack. Along with that undesirable drag force also increases. While tangential component of lift force supports blade rotation, drag force opposes it. So a wind turbine can give maximum performance, when lift to drag ratio is maximum.    This is called as, optimum angle of attack.  Airfoil cross sections are aligned in a way to operate at this optimum angle of attack.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-NnE9GpCaV1E\/UhwljEPlXZI\/AAAAAAAACqE\/sFIh0zjLc0k\/s1600\/lift_force_wind_turbine_blade.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-NnE9GpCaV1E\/UhwljEPlXZI\/AAAAAAAACqE\/sFIh0zjLc0k\/s1600\/lift_force_wind_turbine_blade.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.4 Lift and drag force induced over a wind turbine blade\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E   Even though flow velocity is uniform along the length of the blade, blade velocity increases linearly as we move to the tip. So angle and magnitude of relative velocity (apparent velocity) of wind varies along the length of the blade. Apparent velocity becomes more aligned to chord direction as we move to the tip.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-xLfR33KkmEQ\/UhwlTj9TBqI\/AAAAAAAACp8\/bKWbPppH9bA\/s1600\/change_apparent_velocity.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-xLfR33KkmEQ\/UhwlTj9TBqI\/AAAAAAAACp8\/bKWbPppH9bA\/s1600\/change_apparent_velocity.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.5 Change in apparent velocity along length of the blade\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  So there should be a continuous twist in the blade, so that at every airfoil cross section angle of attack is optimum. \u003C\/p\u003E\u003Ch2\u003EPitching of Blades\u003C\/h2\u003E\u003Cp\u003EWind condition can change at any time.  So it is also possible to rotate wind turbine blades in its own axis, in order to achieve optimum angle of attack with varying wind condition. This is known as pitching of blades. A clever algorithm which uses wind condition and characteristics of wind turbine as input, governs the pitch angle for the maximum power production.\u003C\/p\u003E \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-elrVeGcgDd4\/Uhwl24v-KUI\/AAAAAAAACqs\/YjRU5LYAKA0\/s260\/pitch_control.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-elrVeGcgDd4\/Uhwl24v-KUI\/AAAAAAAACqs\/YjRU5LYAKA0\/s260\/pitch_control.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.6 Schematic of algorithm which governs blade pitching\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E \u003Ch2\u003EBlade Length\u003C\/h2\u003E\u003Cp\u003ENext big factor affecting performance of wind turbine is length of the blade. As we discussed in first video lecture, power extracted by the wind turbine varies according to this equation. So it is clear that, a longer blade will favor the power extraction. But, with increase in blade length, deflection of blade tip due to axial wind force also increases. So blind increase in length of the blade may lead to dangerous situation of collision of blade and tower.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-uq86WUTQpOU\/UhwlSzge3UI\/AAAAAAAACp0\/YPwnSpEfepI\/s1600\/bending_of_blade.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-uq86WUTQpOU\/UhwlSzge3UI\/AAAAAAAACp0\/YPwnSpEfepI\/s1600\/bending_of_blade.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.7 Blade bending due to wind load acting on it\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  With increase in blade length tip velocity increases. Noise produced by the turbine is a strong function of tip velocity. So, it is not permissible to increase blade length after a limit.  Other factor which goes against long blades is requirement of  huge mechanical  structures which leads to heavy investment.\u003C\/p\u003E\u003Ch2\u003EDetermination of Tower Height\u003C\/h2\u003E\u003Cp\u003EMost critical factor of wind turbine design is determination of proper tower height. Power input available for wind turbine varies as cube of wind speed. So a small change in wind speed will have huge effect on power production. A typical wind speed increase from ground level is shown in figure. So from power extraction point of view, it is desired to have tower height as high as possible. But difficulty in road transportation and structural design problems put a limit on maximum tower height possible.   \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-GWsEHeiLVUM\/Uhwl0Q4MSkI\/AAAAAAAACqk\/THjht81ZRbQ\/s297\/tower_height_altitude.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-GWsEHeiLVUM\/Uhwl0Q4MSkI\/AAAAAAAACqk\/THjht81ZRbQ\/s297\/tower_height_altitude.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.8 Wind velocity increases with altitude resulting in more power extraction\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E \u003C\/p\u003E   \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E "},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/1449482093192519788"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/1449482093192519788"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2013\/08\/Wind-Turbine-Design.html","title":"Wind Turbine Design"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/img.youtube.com\/vi\/p5k2LhKBSgQ\/default.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-7054646242192322158"},"published":{"$t":"2014-04-08T00:06:00.000-07:00"},"updated":{"$t":"2016-04-28T01:24:28.974-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Fluid Mechanics"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Thermal Engineering"}],"title":{"type":"text","$t":"Working of Refrigerator \u0026 Refrigeration Principle"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003ERefrigeration technology is commonly used in domestic and industrial applications. This video gives a detailed and logical introduction to the workings of refrigerators using the vapor compression cycle.\u003Cbr\u003E \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"\/\/www.youtube.com\/embed\/h5wQoA15OnQ\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003E An elaborated webpage version of the video is given below.\u003C\/p\u003E \u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003EThe Basic Principle\u003C\/h2\u003E\u003Cp\u003EThe basic principle of refrigeration is simple. You simply pass a colder liquid continuously around the object that is to be cooled. This will take heat from the object. In the example shown, a cold liquid is passed over an apple, which is to be cooled. Due to the temperature difference, the apple loses heat to the refrigerant liquid. The refrigerant in turn is heated due to heat absorption from the apple.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/-q0TXY1TZjsk\/U0OJ9QEs5pI\/AAAAAAAAC_c\/NKimc9K5ZZk\/s1600\/refrigeration_principle.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/-q0TXY1TZjsk\/U0OJ9QEs5pI\/AAAAAAAAC_c\/NKimc9K5ZZk\/s1600\/refrigeration_principle.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.1 Basic principle of refrigeration is illustrated in this figure\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  It is clear that, if we can produce cold liquid refrigerant continuously, we can achieve continuous refrigeration. This simple fact forms the core of the refrigeration technology. We will next see how this is achieved.\u003C\/p\u003E\u003Ch2\u003EComponents of Refrigerator \u0026 Working\u003C\/h2\u003E\u003Cp\u003EAn inside view of a refrigerator is shown.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/--l8suQ4VhVo\/U0OJ9HGZ_aI\/AAAAAAAAC_Y\/L0Zo2-xuRVs\/s1600\/refrigerator_components.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/--l8suQ4VhVo\/U0OJ9HGZ_aI\/AAAAAAAAC_Y\/L0Zo2-xuRVs\/s1600\/refrigerator_components.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.2 An inside view of a refrigerator\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  It has 4 main components: compressor, condenser, evaporator, and throttling device. Of these components, the throttling device is the one that is responsible for the production of the cold liquid. So we will first analyze the throttling device in a detailed way and move on to the other components.\u003C\/p\u003E  \u003Ch3\u003EThrottling Device\u003C\/h3\u003E \u003Cp\u003EThe throttling device obstructs the flow of liquid; cold liquid is produced with the help of this device. In this case, the throttling device is a capillary tube. The capillary tube has an approximate length of 2 m and an inside diameter of around 0.6 mm, so it offers considerable resistance to the flow.   \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-ljshUNfitNE\/U0OMj1_vHRI\/AAAAAAAAC_0\/M6daSwXCK60\/s1600\/throttling_device_capillary_tube.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-ljshUNfitNE\/U0OMj1_vHRI\/AAAAAAAAC_0\/M6daSwXCK60\/s1600\/throttling_device_capillary_tube.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.3 A Capillary tube: This results in sudden drop in pressure and temperature\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E For effective throttling at the inlet, the refrigerant should be a high-pressure liquid. The throttling device restricts the flow, which causes a tremendous pressure drop. Due to the drop in pressure, the boiling point of the refrigerant is lowered, and it starts to evaporate. The heat required for evaporation comes from the refrigerant itself, so it loses heat, and its temperature drops. If you check the temperature across the throttling device, you will notice this drop.\u003C\/p\u003E \u003Cp\u003EIt is wrong to say that the throttling is a \u003Ci\u003Eprocess\u003C\/i\u003E. We know only the end points of throttling, that is, the states before and after throttling. We don’t know the states in between, since this is a highly irreversible change. So it would be correct to call throttling a phenomenon rather than a process.\u003C\/p\u003E  \u003Ch3\u003EEvaporator - Heat Absorption Process\u003C\/h3\u003E\u003Cp\u003EThe next phase is simple: this cold liquid is passed over the body that has to be cooled. As a result, the refrigerant absorbs the heat. During the heat absorption process, the refrigerant further evaporates and transforms into pure vapor. A proper heat exchanger is required to carry the cold refrigerant over the body. This heat exchanger is known as an evaporator.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-FC05xKPGJTE\/VcwcnbWTDFI\/AAAAAAAADew\/ebkWzCXwJmM\/s1600\/evaporator.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-FC05xKPGJTE\/VcwcnbWTDFI\/AAAAAAAADew\/ebkWzCXwJmM\/s1600\/evaporator.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.4 Cold liquid is passed through a heat exchanger know as evaporator for absorbing heat from the refrigerator\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  So we have produced the required refrigeration effect. If we can return this low-pressure vapor refrigerant to the state before the throttling process (that is the high-pressure liquid state), we will be able to repeat this process. So first step, let’s raise the pressure.\u003C\/p\u003E\u003Ch3\u003ECompressor\u003C\/h3\u003E\u003Cp\u003EA compressor is introduced for this purpose. The compressor will raise the pressure back to its initial level. But since it is compressing gas, along with pressure, temperature will also be increased. This is unavoidable.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/-rLxsoUqh0_Q\/VcwZ3OeqzPI\/AAAAAAAADeU\/omSinLY8NpQ\/s1600\/compressor.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/-rLxsoUqh0_Q\/VcwZ3OeqzPI\/AAAAAAAADeU\/omSinLY8NpQ\/s1600\/compressor.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.5 A compressor is used to raise pressure of the refrigerant\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E  Now the refrigerant is a high-pressure vapor. To convert it to the liquid state, we must introduce another heat exchanger.\u003C\/p\u003E   \u003Ch3\u003ECondenser \u003C\/h3\u003E \u003Cp\u003EThis heat exchanger is fitted outside the refrigerator, and the refrigerant temperature is higher than atmospheric temperature. So heat will dissipate to the surroundings. The vapor will be condensed to liquid, and the temperature will return to a normal level.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-EqPHfJFxh18\/VcwZ3dcZUHI\/AAAAAAAADeY\/DMU5bHPODSU\/s1600\/condenser.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-EqPHfJFxh18\/VcwZ3dcZUHI\/AAAAAAAADeY\/DMU5bHPODSU\/s1600\/condenser.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.6 Condenser heat exchanger is fitted outside the refrigerator so it will reject heat to the surroundings\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E \u003C\/p\u003E \u003Cp\u003ESo the refrigerant is back to its initial state again: a high-pressure liquid. We can repeat this cycle over and over for continuous refrigeration. This cycle is known as the \u003Cb\u003E\u003Ci\u003Evapor compression cycle\u003C\/i\u003E\u003C\/b\u003E. Refrigeration technology based on the vapor compression cycle is the most commonly used one in domestic and industrial applications.\u003C\/p\u003E\u003Ch2\u003ERefrigeration Accessories\u003C\/h2\u003E\u003Cp\u003EYou can find more details on refrigerator components here. Evaporators and condensers have fins attached to them. The fins increase the surface area available for convective heat transfer and thus will significantly enhance heat transfer.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-B1WcKRCSQHk\/U0OJ6Yx_CyI\/AAAAAAAAC_Q\/LYwS3i7mEyA\/s1600\/fins.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-B1WcKRCSQHk\/U0OJ6Yx_CyI\/AAAAAAAAC_Q\/LYwS3i7mEyA\/s1600\/fins.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.7 Fins attached to the condenser and evaporator\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E Since the evaporator is cooling the surrounding air, it is common that water will condense on it, forming frost. The frost will act as an insulator between the evaporator heat exchanger and the surrounding air. Thus it will reduce the effectiveness of the heat removal process. Frequent removal of frost is required to enhance the heat transfer. An automatic defrosting mechanism is employed in all modern refrigerators. \u003C\/p\u003E\u003Ch2\u003EMore on Compressor\u003C\/h2\u003E\u003Cp\u003EApart from raising the pressure, the compressor also helps maintain the flow in the refrigerant circuit. Usually, a hermetically sealed reciprocating type compressor is used for this purpose. You might have noticed that, your household refrigerator consumes a lots of electricity compared to the other devices. In a vapor compression cycle, we have to compress the gas; compressing the gas and raising pressure is a highly energy intensive affair. This is the reason why the refrigerator based on the vapor compression refrigeration technology consumes a lot of electricity.\u003C\/p\u003E   \u003Ch2\u003ECoefficient of Performance\u003C\/h2\u003E\u003Cp\u003EThe heat and power transfer happening in a vapor compression refrigeration circuit is shown below.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-0wBrcK54RFo\/U0OJ4K9AW3I\/AAAAAAAAC_A\/z5JjvjkgIKo\/s1600\/energy_balance_cop.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-0wBrcK54RFo\/U0OJ4K9AW3I\/AAAAAAAAC_A\/z5JjvjkgIKo\/s1600\/energy_balance_cop.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.8 Energy interaction happening in a refrigeration system\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E A simple energy balance of the system yields the following relationship.  \u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"http:\/\/1.bp.blogspot.com\/-5z-JlKDH2A0\/U0Oc7GydCsI\/AAAAAAAADAE\/g7RcvLA1wX8\/s1600\/eqn1.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"\u003E\u003Cimg border=\"0\" src=\"http:\/\/1.bp.blogspot.com\/-5z-JlKDH2A0\/U0Oc7GydCsI\/AAAAAAAADAE\/g7RcvLA1wX8\/s1600\/eqn1.jpg\" \/\u003E\u003C\/a\u003E\u003C\/div\u003E It is often required to evaluate performance of a refrigerator or compare between different refrigeration technologies. A term called Coefficient of Performance (C.O.P) helps in doing this. To understand this term completely, we need to know what is the input and output of a refrigeration system. What we need from a refrigerator is the cooling effect. Or Q\u003Csub\u003EABSORBED\u003C\/sub\u003E is the output of a refrigeration cycle. Input to the refrigerator is the power given to the compressor. So the term C.O.P can easily be defined as output by input and is expressed as follows.\u003C\/p\u003E   \u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"http:\/\/2.bp.blogspot.com\/-EgqBzoMtVMA\/U0Oc7TGlqRI\/AAAAAAAADAI\/1eWlL4pCUNs\/s1600\/eqn2.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"\u003E\u003Cimg border=\"0\" src=\"http:\/\/2.bp.blogspot.com\/-EgqBzoMtVMA\/U0Oc7TGlqRI\/AAAAAAAADAI\/1eWlL4pCUNs\/s1600\/eqn2.jpg\" \/\u003E\u003C\/a\u003E\u003C\/div\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7054646242192322158"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/7054646242192322158"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2014\/04\/working-of-Refrigerator.html","title":"Working of Refrigerator \u0026 Refrigeration Principle"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/3.bp.blogspot.com\/-q0TXY1TZjsk\/U0OJ9QEs5pI\/AAAAAAAAC_c\/NKimc9K5ZZk\/s72-c\/refrigeration_principle.png","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-2819098283098180965"},"published":{"$t":"2013-08-20T18:19:00.001-07:00"},"updated":{"$t":"2016-04-28T01:33:00.429-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Fluid Mechanics"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Hydraulic Machines"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Pelton Turbine - Working \u0026 Design Aspects"},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EPelton turbines\/wheels are suitable for power extraction, when the water energy is available at high head and low flow rate. In this video we will go through working principle and design aspects of Pelton turbine. \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"\/\/www.youtube.com\/embed\/rf9meqw2SQA\"  frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003EFollowing article gives detailed description of the video lecture.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003EPelton Turbine – The Basic Working Principle\u003C\/h2\u003E\u003Cp\u003EWorking principle of Pelton turbine is simple. When a high speed water jet injected through a nozzle hits buckets of Pelton wheel; it induces an impulsive force. This force makes the turbine rotate. The rotating shaft runs a generator and produces electricity.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-F-uljwfx5U0\/UhIyY62IswI\/AAAAAAAACgw\/xWmPhzw_w_k\/s1600\/Pelton_Turbine.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-F-uljwfx5U0\/UhIyY62IswI\/AAAAAAAACgw\/xWmPhzw_w_k\/s1600\/Pelton_Turbine.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.1 Pelton wheel derives rotation from impulse force produced by the water jet\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E In short, Pelton turbine transforms kinetic energy of water jet to rotational energy.\u003C\/p\u003E  \u003Ch2\u003EGoverning in Pelton Wheel\u003C\/h2\u003E\u003Cp\u003EDemand of power may fluctuate over time.  A governing mechanism which controls position of the spear head meets this requirement.  With lowering power demand the spear head at water inlet nozzle is moved in. So that water flow rate is reduced.  If power demand increases spear head is moved out this will increase the flow rate. Following figure illustrates this mechanism. The first position of the spear head produces a low flow rate, while the second position produces a high flow rate.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh5.googleusercontent.com\/-xTz-4anfEYQ\/UhIyZ08fk4I\/AAAAAAAAChA\/aEbBK3yJ5mw\/s1600\/Pelton_Speed_Governing.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh5.googleusercontent.com\/-xTz-4anfEYQ\/UhIyZ08fk4I\/AAAAAAAAChA\/aEbBK3yJ5mw\/s1600\/Pelton_Speed_Governing.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.2 Water flow rate control in Pelton wheel by monitoring position of spear head\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E So in Pelton turbine synchronization between power demand and power supply is met by controlling the water flow rate. The same technique is used in other types hydroelectric turbines. If the power supply is more than the demand, then the turbine will run over speed otherwise in under speed. But such a governing mechanism in turn will balance the power supply and demand and will  make sure that the turbine rotates at a constant specified \u003Ci\u003ERPM\u003C\/i\u003E. This speed should also conforms to the power supply frequency.  So this mechanism acts as a speed governing mechanism of Pelton wheel.\u003C\/p\u003E  \u003Ch2\u003ENumber of Buckets in Pelton Wheel\u003C\/h2\u003E\u003Cp\u003EOne of the most important parameter of Pelton turbine design is number of buckets on the disk. If number of buckets is inadequate, this will result in loss in water jet. That means when one bucket departs from the water jet next bucket may not get engaged with the jet. This will result in loss in water jet for a small time duration, thus sudden drop in turbine efficiency. Following figure illustrates what happens when the number of buckets are lowered. With lowering number of buckets at some point of operation, complete water jet might be lost (3\u003Csup\u003Erd\u003C\/sup\u003E figure). So there should be an appropriate number of buckets, which will make sure that no water is lost (1\u003Csup\u003Est\u003C\/sup\u003E figure).  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh4.googleusercontent.com\/-OPWsJHZSVzo\/UhI0KMmFigI\/AAAAAAAAChs\/jMXsXXIUaKE\/s1600\/number_buckets_pelton_wheel.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh4.googleusercontent.com\/-OPWsJHZSVzo\/UhI0KMmFigI\/AAAAAAAAChs\/jMXsXXIUaKE\/s1600\/number_buckets_pelton_wheel.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.3 Effect of number of buckets on water-bucket interaction\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E  \u003Ch2\u003EPelton Bucket - Design \u0026 Features\u003C\/h2\u003E\u003Cp\u003EMost vital component of Pelton wheel is its bucket. Buckets are casted as single solid piece, in order to avoid fatigue failure. You can note that force acting on the turbine bucket is not constant with time. If you follow one particular bucket, it will have high force for a small time duration (at the time of jet impingement) after that a larger idle period where no jet interaction takes place. So the force acting on the bucket is also not constant. It varies with the time but it is having a cyclic nature.  If bucket were made using pieces by welding attachment such cyclic fore will easily lead to premature fatigue failure.   \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh3.googleusercontent.com\/-usFHByIG1ko\/UhIypT6HDQI\/AAAAAAAAChI\/yxy0uili_zA\/s1600\/Pelton_bucket.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh3.googleusercontent.com\/-usFHByIG1ko\/UhIypT6HDQI\/AAAAAAAAChI\/yxy0uili_zA\/s1600\/Pelton_bucket.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.4 Different views of Pelton bucket\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E \u003Cp\u003EWater jet is split into 2 equal components with help of a splitter. The special shape of bucket makes the jet turn almost 180 degree. This produces an impulsive force on bucket.   Force so produced can easily be derived from Newton’s 2nd law of motion. Blade outlet angle close to 180 degree is usually used in order to maximize impulsive force.\u003C\/p\u003E   \u003C\/p\u003EA cut is provided on bottom portion of buckets.  This makes sure that water jet will not get interfered by other incoming buckets.\u003C\/p\u003E     \u003Ch2\u003EPelton – An Impulse Turbine\u003C\/h2\u003E\u003Cp\u003ESince the water jet is always open to atmosphere, inlet and exit pressure of water jet will be same and will be same as atmospheric pressure. However absolute velocity of fluid will have huge drop from inlet to exit of bucket. This kinetic energy drop is the maximum energy the bucket can absorb.\u003C\/p\u003E\u003Cp\u003ESo it is clear that Pelton turbine gains mechanical energy purely due to change in kinetic energy of jet, not due to pressure energy change. Which means Pelton turbine is a pure impulse machine.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh3.googleusercontent.com\/-RLHs_cFtT1g\/UhI33irS4GI\/AAAAAAAACh4\/_q-yfP03tkQ\/s1600\/Pressure_velocity_variation_Pelton.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh3.googleusercontent.com\/-RLHs_cFtT1g\/UhI33irS4GI\/AAAAAAAACh4\/_q-yfP03tkQ\/s1600\/Pressure_velocity_variation_Pelton.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.5 Pressure and velocity variation across Pelton bucket\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E Impulse force produced by water jet is high when jet is having high velocity. Water stored at high altitude can easily produce high jet velocity. This is the reason why Pelton turbine is most suitable for operation, when water is stored at high altitude.\u003C\/p\u003E\u003Cp\u003EYou can easily understand why there is a nozzle fitted at water jet injection portion. Nozzle will increase velocity of jet further, thus will aid in effective production of impulse force.\u003C\/p\u003E \u003Ch2\u003EExtracting Maximum Power from Water Jet\u003C\/h2\u003E\u003Cp\u003EPelton turbine design is always aimed at extracting maximum power from water jet, or maximizing efficiency. Power extracted by the bucket, \u003Ci\u003EP\u003C\/i\u003E is product of jet impulse force and bucket velocity. \u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh3.googleusercontent.com\/-sqmves8tg6E\/UhJANFQUeJI\/AAAAAAAACiI\/Agv0qpMuCME\/s1600\/eqn.jpg\" imageanchor=\"1\" style=\"margin-left: 1em; margin-right: 1em;\"\u003E\u003Cimg border=\"0\" src=\"https:\/\/lh3.googleusercontent.com\/-sqmves8tg6E\/UhJANFQUeJI\/AAAAAAAACiI\/Agv0qpMuCME\/s1600\/eqn.jpg\" \/\u003E\u003C\/a\u003E\u003C\/div\u003ESo power extraction is maximum when product of impulsive force and bucket velocity is maximum. Let's consider 2 different operating conditions.\u003C\/p\u003E  \u003Cul\u003E\u003Cli\u003E\u003Ch3\u003EBuckets are Held Stationary\u003C\/h3\u003E\u003C\/li\u003E\u003Cp\u003EIf Pelton wheel buckets are held stationary, there will be a huge impulse force produced. But power extraction will be zero since buckets are not moving.\u003C\/p\u003E\u003Cli\u003E\u003Ch3\u003EBucket Speed Same as Jest Speed\u003C\/h3\u003E\u003C\/li\u003E \u003Cp\u003EIf buckets are moving with same speed of jet, water jet won't be able to hit the bucket. This will lead to zero impulse force. Again power extraction will be zero.\u003C\/p\u003E\u003C\/ul\u003E\u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh4.googleusercontent.com\/-E4FYgsv63TI\/UhIyyohjfaI\/AAAAAAAAChg\/jU4WuLrJGxc\/s1600\/bucket_jet_velocities_pelton.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh4.googleusercontent.com\/-E4FYgsv63TI\/UhIyyohjfaI\/AAAAAAAAChg\/jU4WuLrJGxc\/s1600\/bucket_jet_velocities_pelton.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.6 Relative magnitude of bucket and jet velocity is important in power extraction from fluid\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E   In short, power extraction is zero both at zero bucket speed and when bucket speed is same as jet speed. So with respect to jet to bucket speed ratio, power extraction will vary with as shown below.   \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/lh6.googleusercontent.com\/-t15p4QNByv8\/UhIyrjfNGSI\/AAAAAAAAChQ\/-MwT2QEntF0\/s1600\/Power_absorption_graph.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/lh6.googleusercontent.com\/-t15p4QNByv8\/UhIyrjfNGSI\/AAAAAAAAChQ\/-MwT2QEntF0\/s1600\/Power_absorption_graph.png\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.7 This graph shows how power extraction from fluid varies with respect to bucket to jet velocity ratio \u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E   It is clear from the above graph that optimum power extraction happens in between. It can be shown using Euler's turbo machinery equation that maximum power extraction happens when bucket speed is half the jet velocity. So it is always desirable to operate Pelton wheel at this condition. Pelton turbines can give efficiency as high as 90 %, at optimum working conditions.\u003C\/p\u003E   \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E   "},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2819098283098180965"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/2819098283098180965"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2013\/08\/pelton-turbine-wheel-hydraulic-turbine.html","title":"Pelton Turbine - Working \u0026 Design Aspects"}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/lh6.googleusercontent.com\/-F-uljwfx5U0\/UhIyY62IswI\/AAAAAAAACgw\/xWmPhzw_w_k\/s72-c\/Pelton_Turbine.jpg","height":"72","width":"72"}},{"id":{"$t":"tag:blogger.com,1999:blog-7182417135626013721.post-6232785721672319939"},"published":{"$t":"2013-04-18T02:23:00.001-07:00"},"updated":{"$t":"2016-04-28T01:29:11.822-07:00"},"category":[{"scheme":"http://www.blogger.com/atom/ns#","term":"Machine Design"},{"scheme":"http://www.blogger.com/atom/ns#","term":"Mechanics"}],"title":{"type":"text","$t":"Understanding Degrees of Freedom "},"content":{"type":"html","$t":"\u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003Cscript\u003E  (adsbygoogle = window.adsbygoogle || []).push({     google_ad_client: \"ca-pub-2737347269754935\",     enable_page_level_ads: true   }); \u003C\/script\u003E\u003Cp\u003EDegrees of freedom is the one of the most important concept in mechanics. This concept is widely used in robotics and kinematics. D.O.F means how many variables are required to determine position of a mechanism in space. In this video lecture we will understand how to predict degrees of freedom of a mechanism. \u003Cdiv style=\"text-align: center;\"\u003E\u003Ciframe width=\"640\" height=\"360\" src=\"http:\/\/www.youtube.com\/embed\/vOFM8eG8kVc\" frameborder=\"0\" allowfullscreen\u003E\u003C\/iframe\u003E\u003C\/div\u003EDetailed description of the video lecture is given below.\u003C\/p\u003E\u003Chr\u003E\u003Cbr\u003E\u003Ch2\u003E Degrees of Freedom – Examples\u003C\/h2\u003E\u003Cp\u003EConsider the mechanism shown in first figure of Fig.4. Position of this 4 bar mechanism can be completely determined just by knowing angle or position of any  one of the member. So degree of freedom is one. Similarly degree of freedom of the cam and follower mechanism is also one. But to determine position of the slider crank mechanism shown, we should know angle or displacement of at least 2 members. So here degrees of  freedom is 2.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-4MWAjpQP-D4\/UWZy_0nbwgI\/AAAAAAAABmE\/RRGwQwRxqFw\/s1600\/cmparing+Degrees+of+freedom.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-4MWAjpQP-D4\/UWZy_0nbwgI\/AAAAAAAABmE\/RRGwQwRxqFw\/s1600\/cmparing+Degrees+of+freedom.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.1 Examples of degrees of freedom of different mechanisms\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003EYou have predicted D.O.F of some simple mechanisms from your intuition. But for a complex mechanism, such an approach may not work. So  in coming sections we will  see how we can predict D.O.F of a mechanism.\u003C\/p\u003E \u003Ch2\u003E Degrees of Freedom of a Rigid Body\u003C\/h2\u003E\u003Cp\u003EConsider the rigid body shown below, which is situated in space. It could have 3 translatory motions as shown. Also it could have 3 rotary motions as shown.In total we need 6 inputs to determine its position. So degree of freedom of rigid body in space is 6.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-tvTJo-rTKV0\/UWZy8-ow1gI\/AAAAAAAABlg\/6t86oZAHOO0\/s1600\/3+dimensional+mobility.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-tvTJo-rTKV0\/UWZy8-ow1gI\/AAAAAAAABlg\/6t86oZAHOO0\/s1600\/3+dimensional+mobility.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.2 A rigid body in space can have total 6 degrees of freedom\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003EIf the body is in a plane it can have only 3 motions. 2 translational and 1 rotational. So degree of freedom of a rigid body in a plane is 3. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-4JZaUKvvOr4\/UWZzBnk0XiI\/AAAAAAAABmc\/1akVGjTqbX0\/s1600\/planar+mobility.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-4JZaUKvvOr4\/UWZzBnk0XiI\/AAAAAAAABmc\/1akVGjTqbX0\/s1600\/planar+mobility.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.3 A rigid body on plane can have total 3 degrees of freedom\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E\u003Ch2\u003EDegrees of Freedom of a Mechanism\u003C\/h2\u003E\u003Cp\u003EA mechanism is a collection of rigid bodies or links, connected through pairs, provided one link is grounded. Consider the mechanism shown below. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/-Y12MWmM1OcQ\/UW0pqv1m-OI\/AAAAAAAABnI\/F3LzKgiCR8I\/s1600\/planar_mechanism.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/-Y12MWmM1OcQ\/UW0pqv1m-OI\/AAAAAAAABnI\/F3LzKgiCR8I\/s320\/planar_mechanism.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.4 An example of mechanism, it is necessary that one link should be groudnded\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003EIf this system were not connected like this, then each link except the ground would have 3 degrees of freedom.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/4.bp.blogspot.com\/-Q5HG0rIYVZk\/UWZzAs6bOxI\/AAAAAAAABmQ\/KJp_r3uG1PI\/s1600\/dis+assembled+mechanism.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/4.bp.blogspot.com\/-Q5HG0rIYVZk\/UWZzAs6bOxI\/AAAAAAAABmQ\/KJp_r3uG1PI\/s1600\/dis+assembled+mechanism.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.5 If links were not connected each link would have 3 D.O.F, except the ground\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003ESo total degrees of freedom, or mobility is \u003Ci\u003E3(N-1)\u003C\/i\u003E. \u003Ci\u003EN\u003C\/i\u003E represents total number of links. In this case \u003Ci\u003EN\u003C\/i\u003E is 3. But when we connect it together through pairs, links will not have the same 3 degrees of freedom.\u003C\/p\u003E\u003Cp\u003EIf joint between 2 links is having surface contact as shown below, then both the links will have same translatory motion, in X and Y directions.So for each such pairs, there will be a deduction of 2 mobility from total mobility. Where \u003Ci\u003EL\u003Csub\u003EP\u003C\/sub\u003E\u003C\/i\u003E represents number of pairs with surface contacts. Such pairs are called lower pairs. In this case we have 2 lower pairs.\u003C\/p\u003E\u003Cp\u003ENow consider the joint which is having a line contact. If joint between 2 links is having line or point contact, both the link should have same translational motion along the common normal. However it could have different motion, in tangential direction. So for each such pairs, there will be deduction of 1 mobility from total mobility. This kind of pair is called higher pair. Here we have got 1 higher pair.  \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/1.bp.blogspot.com\/-FyjRLTYlz0c\/UWZzApms7AI\/AAAAAAAABmU\/QdeAq_egnTI\/s1600\/pairs_in+mechanism.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/1.bp.blogspot.com\/-FyjRLTYlz0c\/UWZzApms7AI\/AAAAAAAABmU\/QdeAq_egnTI\/s1600\/pairs_in+mechanism.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.6 Lower pairs and higher pairs in a mechanism, a lower pair arrests 2 D.O.F, while a higher pair arrests one D.O.F\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E So this mechanism has got 1 degree of freedom. Means, by knowing position of only one cam, we can completely determine this mechanism.\u003C\/p\u003E \u003Cp\u003EThe general equation to find out degrees of freedom of a planar mechanism is given below. This equation is also  known as \u003Ci\u003EKuthbach equation\u003C\/i\u003E. \u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"https:\/\/4.bp.blogspot.com\/-5JcsK8n-SSA\/UW-4MgnKzBI\/AAAAAAAABnY\/_f5E_p1p4o4\/s1600\/mobility+equation+planar.GIF\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/4.bp.blogspot.com\/-5JcsK8n-SSA\/UW-4MgnKzBI\/AAAAAAAABnY\/_f5E_p1p4o4\/s1600\/mobility+equation+planar.GIF\" \/\u003E\u003C\/a\u003E\u003C\/div\u003EHere \u003Ci\u003EN\u003C\/i\u003E represent total number of links in the mechanism. \u003Ci\u003EL\u003Csub\u003EP\u003C\/sub\u003E\u003C\/i\u003E and \u003Ci\u003EH\u003Csub\u003EP\u003C\/sub\u003E\u003C\/i\u003E represent number of lower pairs and higher pairs respectively.\u003C\/p\u003E\u003Ch3\u003E 4 Bar Linkage \u003C\/h3\u003E\u003Cp\u003EBack to same old planar mechanisms.This mechanism is having 4 links, and 4 lower pairs. So you can predict from \u003Ci\u003EKuthbach equation\u003C\/i\u003E that mobility of the mechanism is 1. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/-Z5XSJTsPp8A\/UWZy9_2vEhI\/AAAAAAAABlw\/h5sg8fG-gUI\/s1600\/4+bar+linkage.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/-Z5XSJTsPp8A\/UWZy9_2vEhI\/AAAAAAAABlw\/h5sg8fG-gUI\/s1600\/4+bar+linkage.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.7 4 bar linkage, it is having 4 links and 4 lower pairs\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E\u003Ch3\u003ECam and Follower \u003C\/h3\u003E\u003Cp\u003ECam and follower is having 3 links, 2 lower pairs, and one higher pair.So mobility is again one. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/3.bp.blogspot.com\/-veVL9w8IU9k\/UWZy-onr2fI\/AAAAAAAABmA\/m1p2F7QjwG0\/s1600\/Cam+and+Follower.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/3.bp.blogspot.com\/-veVL9w8IU9k\/UWZy-onr2fI\/AAAAAAAABmA\/m1p2F7QjwG0\/s1600\/Cam+and+Follower.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.8 Cam and follower, 3 links, 2 lower pairs, 1 higher pair\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E  \u003Ch3\u003E5 bar linkage\u003C\/h3\u003E\u003Cp\u003EThis mechanism is having 5 links and 5 lower pairs. So mobility is 2. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-MgyBWB-msis\/UWZy-jysQcI\/AAAAAAAABl8\/c6s5YdVySEY\/s1600\/5+bar+linkage.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-MgyBWB-msis\/UWZy-jysQcI\/AAAAAAAABl8\/c6s5YdVySEY\/s1600\/5+bar+linkage.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.9 5 bar linkage, 5 links, 5 lower pairs\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E \u003Ch2\u003EA 3 Dimensional Mechanism\u003C\/h2\u003E\u003Cp\u003EIf the mechanism is 3 dimensional in nature, you could easily derive an equation for mobility using the same concept. So equation for degree of freedom would be as follows  \u003Cdiv class=\"separator\" style=\"clear: both; text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-gOqV58HxU7A\/UWZy88T9sgI\/AAAAAAAABlo\/Spc2SXDKDyA\/s1600\/3d_mobility_equation.png\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-gOqV58HxU7A\/UWZy88T9sgI\/AAAAAAAABlo\/Spc2SXDKDyA\/s1600\/3d_mobility_equation.png\" \/\u003E\u003C\/a\u003E\u003C\/div\u003E  Where \u003Ci\u003EP\u003Csub\u003En\u003C\/sub\u003E\u003C\/i\u003E represents number of pairs which block \u003Ci\u003E'n'\u003C\/i\u003E degrees of freedom. The main thing here will be determination of nature of pair. You can use this equation to predict D.O.F following 3 dimensional mechanism. \u003Ctable align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"tr-caption-container\" style=\"margin-left: auto; margin-right: auto; text-align: center;\"\u003E\u003Ctbody\u003E\u003Ctr\u003E\u003Ctd style=\"text-align: center;\"\u003E\u003Ca href=\"https:\/\/2.bp.blogspot.com\/-piwncg1pRDg\/UWZy88GFl3I\/AAAAAAAABlk\/hOwk78T4aiI\/s1600\/3+dimensional+mechanism.jpg\" imageanchor=\"1\" \u003E\u003Cimg border=\"0\" src=\"https:\/\/2.bp.blogspot.com\/-piwncg1pRDg\/UWZy88GFl3I\/AAAAAAAABlk\/hOwk78T4aiI\/s1600\/3+dimensional+mechanism.jpg\" \/\u003E\u003C\/a\u003E\u003C\/td\u003E\u003C\/tr\u003E\u003Ctr\u003E\u003Ctd class=\"tr-caption\" style=\"text-align: center;\"\u003EFig.10 A 3 dimensional mechansim\u003C\/td\u003E\u003C\/tr\u003E\u003C\/tbody\u003E\u003C\/table\u003E\u003C\/p\u003E \u003Cscript async src=\"\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"\u003E\u003C\/script\u003E\u003C!-- Responsive ad --\u003E\u003Cins class=\"adsbygoogle\"      style=\"display:block\"      data-ad-client=\"ca-pub-2737347269754935\"      data-ad-slot=\"7774217985\"      data-ad-format=\"auto\"\u003E\u003C\/ins\u003E\u003Cscript\u003E(adsbygoogle = window.adsbygoogle || []).push({}); \u003C\/script\u003E"},"link":[{"rel":"edit","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/6232785721672319939"},{"rel":"self","type":"application/atom+xml","href":"http:\/\/www.blogger.com\/feeds\/7182417135626013721\/posts\/default\/6232785721672319939"},{"rel":"alternate","type":"text/html","href":"http:\/\/www.learnengineering.org\/2013\/04\/degrees-of-freedom-mechanics.html","title":"Understanding Degrees of Freedom "}],"author":[{"name":{"$t":"Sabin M"},"uri":{"$t":"https:\/\/plus.google.com\/113983923192891667856"},"email":{"$t":"noreply@blogger.com"},"gd$image":{"rel":"http://schemas.google.com/g/2005#thumbnail","width":"32","height":"32","src":"\/\/lh4.googleusercontent.com\/-7s2C1CoKPjM\/AAAAAAAAAAI\/AAAAAAAADuk\/p4kg_Q3BKZA\/s512-c\/photo.jpg"}}],"media$thumbnail":{"xmlns$media":"http://search.yahoo.com/mrss/","url":"https:\/\/img.youtube.com\/vi\/vOFM8eG8kVc\/default.jpg","height":"72","width":"72"}}]}});