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Automobile unit 3 transmission systems

AUTOMOBILE ENGINEERING NOTES/PPT FOR MECHANICAL, PRODUCTION AND AUTOMOBILE ENGINEERING

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Automobile unit 3 transmission systems

  1. 1. UNIT - 3 TRANSMISSION SYSTEMS Prepared By:K.Rajesh, AP/Mech,RMKCET
  2. 2. TOPICS TO BE DISCUSSED  Clutch-types and construction  Gear boxes  Gear shift mechanisms  Over drive  Transfer box  Fluid flywheel –torque converter  Propeller shaft  Slip joints  universal joints  Differential  Rear axle  Hotchkiss Drive andTorqueTube Drive Prepared By:K.Rajesh, AP/Mech,RMKCET
  3. 3. TRANSMISSION SYSTEM INTRODUCTION  Transmission system is the system by means of which power developed by the engine is transmitted to the road wheels to propel the vehicle.  In automobiles the power is developed by the engine which is in turn used to turn the wheels. Prepared By:K.Rajesh, AP/Mech,RMKCET
  4. 4. REQUIREMENT OF TRANSMISSION SYSTEM  To provide for disconnecting the engine from the driving wheels.  When the engine is running, to enable the connection to the driving wheels to be made smoothly and without shock.  To enable the leverage between the engine and driving wheels to be varied.  It must reduce the drive-line speed from that of the engine to that of thedriving  Turn the drive, if necessary, through 90° or perhaps otherwise realignit.  Enable the driving wheels to rotate at different speeds.  Provide for relative movement between the engine and driving wheels. Prepared By:K.Rajesh, AP/Mech,RMKCET
  5. 5. COMPONENTS AND ITS FUNCTION Prepared By:K.Rajesh, AP/Mech,RMKCET
  6. 6. The functions of the components are as follows  Clutch is used for disconnecting the engine from the driving wheels and it must also enable the driver to connect the engine.  Gearbox is to enable the driver to change the leverage between the engine and driving wheels to suit the prevailing conditions gradient, load, speed required, etc.  Propeller shaft transmits the drive on to the back axle  Universal joints at its ends allow both the engine-and-Gearbox assembly and the back axle to move relative to one another, as their spring elements deflect. Prepared By:K.Rajesh, AP/Mech,RMKCET
  7. 7.  Sliding joint accommodates variations in length of the propeller shaft as its rear end rises and falls vertically with the back axle.  Differential gearing, which shares the driving torque equally between the two road wheels  Transfer box is to transfer the power and torque from the main gearbox to both the front and rear axles. Prepared By:K.Rajesh, AP/Mech,RMKCET
  8. 8. CLUTCH  A clutch is a releasable coupling connecting the adjacent ends of two coaxial shafts. It is said to be engaged or, in, when the shafts are coupled, and disengaged, or out, when they are released.  Mechanical clutches fall into two main categories: 1. Positive engagement 2. Progressive engagement. Prepared By:K.Rajesh, AP/Mech,RMKCET
  9. 9.  Positive engagement, so that no torque can be transmitted from the driving to the driven shaft, or positively engaged, in which case the shafts rotate together, connected by some mechanical devices such as splines, keys or dogs.  Progressive type is gradually engaged, so that the speed of the driving shaft falls while, simultaneously, that of the driven shaft rises from its initial stationary state until both are rotating at equal speeds. Prepared By:K.Rajesh, AP/Mech,RMKCET
  10. 10. FUNCTIONS OF CLUTCH • To permit engagement or disengagement with gear box • To transmit the engine power to the rear wheals smoothly without shock. • It should dissipate the heat produced due to friction contact • It should be dynamically balanced to the vibration in the transmission system. • To permit the engaging of the gears when the vehicle is in motion without damaging the gear wheels. Prepared By:K.Rajesh, AP/Mech,RMKCET
  11. 11. TYPES OF CLUTCH ❖ Single plate ❖ Multiplate ❖ Cone clutch ❖ Centrifugal clutch ❖ Semi centrifugal clutch ❖ Hydraulic clutch ❖ Vaccum clutch ❖ Electromagnetic clutch Prepared By:K.Rajesh, AP/Mech,RMKCET
  12. 12. PARTS OF THE CLUTCH 1. Fly wheel 2. Clutch plate or disc plate 3. Pressure plate 4. Clutch cover assembly 5. Release mechanism 6. Withdrawal force & rearing 7. Primary or clutch shaft Prepared By:K.Rajesh, AP/Mech,RMKCET
  13. 13. Prepared By:K.Rajesh, AP/Mech,RMKCET
  14. 14. SINGLE PLATE CLUTCH: • It is most commonly used in motor vehicle such as cars,trucks & tractors. Prepared By:K.Rajesh, AP/Mech,RMKCET
  15. 15. CLUTCH OVERVIEW Prepared By:K.Rajesh, AP/Mech,RMKCET
  16. 16. T T W (axial thrust)W Friction plate Friction liningPressure plates springs Single-plate Friction Clutch (Disengaged position) Driving shaft Driven shaft Flat-plate friction clutches Prepared By:K.Rajesh, AP/Mech,RMKCET
  17. 17. Single-plate Friction Clutch (Engaged position) T T W (axial thrust) W Friction plate Friction lining Pressure plates springs Driving shaft Driven shaft Flat-plate friction clutches Prepared By:K.Rajesh, AP/Mech,RMKCET
  18. 18. ADVANTAGES • It makes easy to change gears than cone type. • It is reliable than cone clutch. DISADVANTAGES • It requires more force to release. • Space required to accommodate the clutch is more as compare to multi plate clutch. Prepared By:K.Rajesh, AP/Mech,RMKCET
  19. 19. DIAPHRAGM CLUTCH ❖ The construction of this type of clutch is similar to that of single plate clutch except that here diaphragm spring called belleville springs are used instead of the ordinary coil springs. ❖ This type of clutch is quite advantage because it requires no release levers and the spring itself act as series of levers. Prepared By:K.Rajesh, AP/Mech,RMKCET
  20. 20. Prepared By:K.Rajesh, AP/Mech,RMKCET
  21. 21. Diaphragm clutch Prepared By:K.Rajesh, AP/Mech,RMKCET
  22. 22. ADVANTAGES ❖ This requires lower operating effort due to reduced friction in the clutch mechanism. ❖ There is a constant and uniform load on the driven plate thorughout the life of the clutch. ❖ Due to its compact size, clutch housing required is quite short. Prepared By:K.Rajesh, AP/Mech,RMKCET
  23. 23. MULTI-PLATE CLUTCH • Multi-plate clutch are used in heavy vehicles with racing cars and motorcycle for transmitting high torque. • As compare to single plate clutch these are smoother and easier to operate due to their assembly of friction surfaces contact. Prepared By:K.Rajesh, AP/Mech,RMKCET
  24. 24. ADVANTAGES • Increased torque transmission capacity. • Highly reliable. • Suitable for heavy vehicles. Prepared By:K.Rajesh, AP/Mech,RMKCET
  25. 25. CONE CLUTCH  The contact surface of this type of clutch are in the form of cones, it is called as cone clutch.  It consists of two cones having leather facings.  The cones are known as male and female cones. Prepared By:K.Rajesh, AP/Mech,RMKCET
  26. 26. ADVANTAGES  Normal force acting on the contact surface is larger than the axial force reduces the effort required to operate the clutch. DISADVANTAGES  A small amount of wear on cone surface results in considerable axial movement of the male cone for which it will be difficult to allow Prepared By:K.Rajesh, AP/Mech,RMKCET
  27. 27. CENTRIFUGAL CLUTCH  This clutch is controlled by the engine speed through an accelerator.  When the engine speed falls down, the clutch will automatically disengaged the speed will raise above the predetermined value and the clutch is engaged. Prepared By:K.Rajesh, AP/Mech,RMKCET
  28. 28. Centrifugal clutch Prepared By:K.Rajesh, AP/Mech,RMKCET
  29. 29. SEMI-CENTRIFUGAL CLUTCH ❖ These clutches are similar to the centrifugal clutches with only difference that here relatively light clutch pressure springs exerting low pressure at idling speed are used. ❖ In this clutch, the pressure between the plates is increased as the speed of rotation of the clutch increases in proportion to the pressure requirements. Prepared By:K.Rajesh, AP/Mech,RMKCET
  30. 30. Semi-centrifugal clutchPrepared By:K.Rajesh, AP/Mech,RMKCET
  31. 31. HYDRAULIC CLUTCH ❖ When the clutch is located at distance from the driver its difficult run cables or rods. ❖ In heavy vehicles in order to transfer large power high spring pressure clutches are required. ❖ High spring pressure requires more human effort and hence use of hydralics will reduce effort required. Prepared By:K.Rajesh, AP/Mech,RMKCET
  32. 32. Hydraulic clutchPrepared By:K.Rajesh, AP/Mech,RMKCET
  33. 33. ELECTRO-MAGNETIC CLUTCH ❖ An electro-magnetic clutch consists of a engine flywheel provided with electric winding. ❖ A driven plate lined with friction materials is provided. ❖ It is free to move on splines of the gearbox shaft. ❖ A pressure plate is applied for engaging or disengaging the clutch. Prepared By:K.Rajesh, AP/Mech,RMKCET
  34. 34. Electro-magnetic clutch Prepared By:K.Rajesh, AP/Mech,RMKCET
  35. 35. VACUUM CLUTCH ❖ The vacuum clutch is operated in the same way as the hydraulic clutch. ❖ The only difference is that it is operated by vacuum pressure whereas the hydraulic clutch is operated by oil pressure. ❖ In vacuum clutches the partial vacuum existing in the engine manifold is used for operating it. Prepared By:K.Rajesh, AP/Mech,RMKCET
  36. 36. Vacuum clutch Prepared By:K.Rajesh, AP/Mech,RMKCET
  37. 37. GEAR BOX  The transmission is part of the power train. It consists of a metal case filled with gears.  It is usually located in the rear of the engine between the clutch housing and the propeller shaft.  It transfers engine power from the clutch shaft to the propeller shaft. It allows the driver or operator to control the power and speed of the vehicle  A gearbox is necessary, therefore, so that the driver can regulate torque by selecting the appropriate speed range or, in other words, the vehicle speed at which maximum torque is obtainable Prepared By:K.Rajesh, AP/Mech,RMKCET
  38. 38. Prepared By:K.Rajesh, AP/Mech,RMKCET
  39. 39. Prepared By:K.Rajesh, AP/Mech,RMKCET
  40. 40. gearbox Prepared By:K.Rajesh, AP/Mech,RMKCET
  41. 41. PURPOSE OF THE TRANSMISSION  Provide a means to vary torque ratio between the engine and the road wheels as required.  According to the requirement the speed can be varied.  Provides a neutral position.  A means to back the car by reversing the direction of rotation of the drive is also provided by the transmission. Prepared By:K.Rajesh, AP/Mech,RMKCET
  42. 42. TYPES OF GEARBOX 1. Manual transmission a) Sliding mesh gearbox b) Constant mesh gearbox c) Synchromesh gearbox 2. Epicyclic gearbox 3. Automatic gearbox a) Hydromatic gearbox b) Torque converter gearbox Prepared By:K.Rajesh, AP/Mech,RMKCET
  43. 43. GEAR BOXE- MANUAL 1. Constant mesh gears. 2. Primary shaft (Clutch shaft) 3. Spigot bearing. 4. Main shaft. 5. Lay shaft (counter shaft) Prepared By:K.Rajesh, AP/Mech,RMKCET
  44. 44. SLIDING MESH GEARBOX PRIMARY SHAFT  This shaft transmits the drive from the clutch to the gearbox .  At the end, the shaft is supported by a spigot bearing positioned close to the splines on to which the clutch driven plate is connected.  The main load on this shaft is taken by a bearing; normally a sealed radial ball type, positioned close to an input gear called a constant mesh pinion  The gear is so named because it is always in mesh with a larger gear  Small driving gear is called a pinion and a large gear a wheel. Prepared By:K.Rajesh, AP/Mech,RMKCET
  45. 45. LAYSHAFT  This shaft, which is normally fixed to the gearbox casing, supports the various-sized driving pinions of the lay shaft gear cluster MAIN SHAFT  This splined output shaft carries spur gearwheels that slide along the shaft to engage with the appropriate lay shaft gears.  At the ‘front’ end, the main shaft is supported by a spigot bearing situated in the centre of the constant mesh pinion. Prepared By:K.Rajesh, AP/Mech,RMKCET
  46. 46. Prepared By:K.Rajesh, AP/Mech,RMKCET
  47. 47. Sliding mesh gearbox Prepared By:K.Rajesh, AP/Mech,RMKCET
  48. 48. Prepared By:K.Rajesh, AP/Mech,RMKCET
  49. 49. Prepared By:K.Rajesh, AP/Mech,RMKCET
  50. 50. CONSTANT MESH GEARBOX  There are many different forms of constant-mesh gearbox, in some of which the various gears slide axially along their shafts, while in others they have no axial freedom.  The characteristic feature of this type of gearbox is, however, that all the pairs of wheels are always in mesh  To eliminate the noise developed in the old spur-tooth type of gears used in the sliding gear transmission, the constant-mesh transmission that contains helical gears.  The main shaft meshing gears are arranged so that they cannot move endwise. They are supported by roller bearings that allow them to rotate independently of the main shaft Prepared By:K.Rajesh, AP/Mech,RMKCET
  51. 51. CONSTANT MESH GEARBOX Prepared By:K.Rajesh, AP/Mech,RMKCET
  52. 52. Layout Of Constantmesh GearboxPrepared By:K.Rajesh, AP/Mech,RMKCET
  53. 53. Constant mesh gearbox Prepared By:K.Rajesh, AP/Mech,RMKCET
  54. 54. Prepared By:K.Rajesh, AP/Mech,RMKCET
  55. 55. Prepared By:K.Rajesh, AP/Mech,RMKCET
  56. 56. Constantmesh Gear Box Gear Position NEUTRAL FIRST GEAR SECOND GEAR THIRD GEAR Prepared By:K.Rajesh, AP/Mech,RMKCET
  57. 57. FORTH GEAR REVERSE GEAR Constantmesh Gear Box Gear Position Prepared By:K.Rajesh, AP/Mech,RMKCET
  58. 58. SYNCHROMESH GEARBOX  The synchromesh transmission is a type of constant- mesh transmission.  It synchronizes the speeds of mating parts before they engage to allow the selection of gears without their clashing.  It employs a combination metal to metal friction cone clutch and a dog or gear positive clutch.  These clutches allow the main drive gear and second-speed main shaft gear to engage with the transmission main shaft.  The friction cone clutch engages first, bringing the driving and driven members to the same speed, after which the dog clutch engages easily without clashing. Prepared By:K.Rajesh, AP/Mech,RMKCET
  59. 59.  This process is accomplished in one continuous operation when the driver declutches and moves the control lever in the usual manner. Synchromesh gearboxPrepared By:K.Rajesh, AP/Mech,RMKCET
  60. 60. Prepared By:K.Rajesh, AP/Mech,RMKCET
  61. 61. Synchromesh gearboxPrepared By:K.Rajesh, AP/Mech,RMKCET
  62. 62. Prepared By:K.Rajesh, AP/Mech,RMKCET
  63. 63. Prepared By:K.Rajesh, AP/Mech,RMKCET
  64. 64. Synchromesh gearbox synchronizerPrepared By:K.Rajesh, AP/Mech,RMKCET
  65. 65. ADVANTAGES  Gear changing is very much simplified.  Reduction in gear wear occurs.  It allows the usage of helical gears that runs quickly.  The design is very much complex.  Initial cost is high  Quick change of gears occurs due to noise of crashing. DISADVANTAGES Prepared By:K.Rajesh, AP/Mech,RMKCET
  66. 66. AUTOMATIC GEARBOX  Most modern automatic gearboxes have a set of gears called a planetary or epicyclic gear train.  In ordinary gearing, the axes of the various gears are fixed. These gears are simply rotated about their axes.  A planetary gear set consists of a central gear called the sun gear, an outer ring with internal gear teeth (also known as the annulus, or ring gear), and two or three gears known as planet gears that rotate between the sun and ring gears.  The drive train is coupled to a mechanism known as a torque converter, which acts as a fluid drive between the engine and transmission.  If the sun gear is locked and the planets driven by the planet carrier, the output is taken from the ring gear, achieving a speed increase. EPICYCLIC GEARBOX Prepared By:K.Rajesh, AP/Mech,RMKCET
  67. 67. EPICYCLIC GEARBOX…..  If the ring gear is locked and the sun gear is driven, the planet gears transmit drive through the planet carrier and speed is reduced.  With power input going to the sun gear and with the planet carrier locked, the ring gear is driven, but transmits drive in reverse.  To achieve direct drive without change of speed or direction of rotation, the sun is locked to the ring gear and the whole unit turns as one.  The same effect can also be achieved by locking the planet gears to the planet carrier.  Most automatic gearboxes have three forward speeds, and use two sets of epicyclic gears. Prepared By:K.Rajesh, AP/Mech,RMKCET
  68. 68. EPICYCLIC GEARBOX…..  The locking sequences of the epicyclic gear train are achieved by hydraulic pressure operating brake bands or multi-plate clutches.  The bands are tightened round the ring gear to prevent it turning, and the clutches are used to lock the sun gear and planets.  The correct sequence of pressure build-up and release is controlled by a complex arrangement of hydraulic valves in conjunction with sensors that respond to engine load, road speed and throttle opening.  A mechanism linked to the throttle - known as a kick down - is used to effect a change-down for rapid acceleration. When you press down the accelerator suddenly to its full extent, a lower gear is selected almost instantly.  Most automatic gearboxes have an override system so that the driver can hold a low gear as required. Prepared By:K.Rajesh, AP/Mech,RMKCET
  69. 69. Prepared By:K.Rajesh, AP/Mech,RMKCET
  70. 70. Prepared By:K.Rajesh, AP/Mech,RMKCET
  71. 71. Prepared By:K.Rajesh, AP/Mech,RMKCET
  72. 72. Prepared By:K.Rajesh, AP/Mech,RMKCET
  73. 73. Prepared By:K.Rajesh, AP/Mech,RMKCET
  74. 74. Prepared By:K.Rajesh, AP/Mech,RMKCET
  75. 75. ADVANTAGES  The planetary gears are in constant mesh. Hence dos clutches or sliding gears are not used.  It is distributed over several gears wheels instead of having the load on only one pair of gears.  A greater area of gear tooth contact can be obtained due to distribution of loads. Prepared By:K.Rajesh, AP/Mech,RMKCET
  76. 76. TRANSFER BOX  A transfer box is interposed between the gearbox and back axle unit. The function of transfer box is to transfer the drive from the main gearbox to both the front and rear axles. Prepared By:K.Rajesh, AP/Mech,RMKCET
  77. 77. Prepared By:K.Rajesh, AP/Mech,RMKCET
  78. 78. Prepared By:K.Rajesh, AP/Mech,RMKCET
  79. 79. Prepared By:K.Rajesh, AP/Mech,RMKCET
  80. 80. Prepared By:K.Rajesh, AP/Mech,RMKCET
  81. 81. FLUID FLYWHEEL  A fluid coupling or hydraulic coupling is a hydrodynamic device used to transmit rotating mechanical power. It has been used in automobile transmission as an alternative to a mechanical clutch.  It couples the driving member with driven member through a media of fluid. Two turbines (fan like components):  One connected to the input shaft; known as the pump or impellor, primary wheel input turbine  The other connected to the output shaft, known as the turbine, output turbine, secondary wheel or runner Prepared By:K.Rajesh, AP/Mech,RMKCET
  82. 82. Prepared By:K.Rajesh, AP/Mech,RMKCET
  83. 83. Prepared By:K.Rajesh, AP/Mech,RMKCET
  84. 84. Fluid flywheel Prepared By:K.Rajesh, AP/Mech,RMKCET
  85. 85. Prepared By:K.Rajesh, AP/Mech,RMKCET
  86. 86. ADVANTAGES  It gives a smoother power takes up than the centrifugal type, when the engine is accelerated.  There is no wear on moving parts.  No need of adjustments is required.  It is simple in design.  No skill is required for operation. Prepared By:K.Rajesh, AP/Mech,RMKCET
  87. 87. DISADVANTAGES  There is a drag on the gear box-shaft even the slip is 100%.  It has the gear changing difficult with the ordinary crash type gearbox. Prepared By:K.Rajesh, AP/Mech,RMKCET
  88. 88. TORQUE CONVERTER  A torque converter is a device which performs a function similar to that of a gearbox.  But whereas a gearbox provides only a small number of fixed ratios the torque converter provides a continuous variation of ratio from the lowest to the highest.  Torque converters all consist of the driving element (impeller) which is connected to the engine, the driven element (rotor) which is connected to the propeller shaft, and the fixed Element (reaction member) which is fixed to the frame. Prepared By:K.Rajesh, AP/Mech,RMKCET
  89. 89. Prepared By:K.Rajesh, AP/Mech,RMKCET
  90. 90. TORQUE CONVERTER Prepared By:K.Rajesh, AP/Mech,RMKCET
  91. 91. Prepared By:K.Rajesh, AP/Mech,RMKCET
  92. 92. Prepared By:K.Rajesh, AP/Mech,RMKCET
  93. 93. GEAR SHIFT MECHANISM Prepared By:K.Rajesh, AP/Mech,RMKCET With the gearbox of the conventional car installed right behind the clutch and the gear lever placed close to the driver, the two must be connected by a remote control rod in the gear box casing.
  94. 94. Prepared By:K.Rajesh, AP/Mech,RMKCET The striker rod of a sliding selector mechanism is guided across the gearbox by the driver and moves the guard to expose the slot in a sleeve. The striker rod enters the slot, and further movement of the gear lever slides the sleeve along its rod to engage a gear. A locking ball engages a recess in the rod to hold the sleeve.
  95. 95. Prepared By:K.Rajesh, AP/Mech,RMKCET The ball-type selector has a similar striker rod but a different guard, which is part of the locking plunger. When the striker moves sideways it disengages the plunger and engages the selector sleeve's slot. Movement of the plunger also unlocks the selector sleeve, so it is then free to slide along its rod and engage a gear.
  96. 96. Prepared By:K.Rajesh, AP/Mech,RMKCET The rod of a column-mounted gearchange runs down either the side or centre of the steering column. Two movements, raising the lever and turning the rod, select and engage the gears.
  97. 97. Prepared By:K.Rajesh, AP/Mech,RMKCET The gearchange used on the Renault 4 ran through the fascia to the gearbox. Twisting the rod selected the gear (via the auxiliary lever) and sliding the rod engaged it.
  98. 98. Prepared By:K.Rajesh, AP/Mech,RMKCET The selection mechanism of the Vauxhall Viva (GM) had a toothed rod inside a slotted collar. The rod was turned to engage a shoulder on a selector fork, then moved backward or forward to slide the selector and dog clutch into position. The collar ensured that only one fork was engaged at a time.
  99. 99. Prepared By:K.Rajesh, AP/Mech,RMKCET The Ford Escort system centres on a single rod, on which the forward speed selector forks are mounted. Connected to the gear lever, this rod also carried an arm and peg. When the gear lever was moved across the "gate" the rod turned, and the peg engaged a slot in the appropriate selector fork - that for first/second gear was engaged here. The gear lever was then moved forward, so sliding the selector fork backwards, while the other forks were held in position by the locking plate.
  100. 100. PROPELLER SHAFT  Propeller shaft transmits the drive from the engine to the drive axles.  Propeller shaft consists of three main parts 1. Shaft 2. Universal joints 3. Slip joints Prepared By:K.Rajesh, AP/Mech,RMKCET
  101. 101. Prepared By:K.Rajesh, AP/Mech,RMKCET
  102. 102. Propeller shaft figurePrepared By:K.Rajesh, AP/Mech,RMKCET
  103. 103. 1. SHAFT  Shaft is the member which transmits the power. It needs to withstand torsional loads mainly. Normally the shafts are of tubular cross sections. They needs to be well balanced to avoid whirling at high speeds.  Materials used for shafts are steel aluminum or composites materials.  The mass of the shaft has to be made small to avoid high rotational moment of inertia which decreases acceleration capabilities of the system. Prepared By:K.Rajesh, AP/Mech,RMKCET
  104. 104. TYPES OF PROPELLER SHAFTS Solid or open type Hollow or enclosed type 1. Used in heavy commercial vehicles different types of cars and light vehicles. 2. It has tubular cross section. 3.Two universal joints are connected at the ends. 4. Propeller shaft is long comparatively so it is made up of two portions. 5. It is connected to the chassis with the help of bearing. 1. The propeller shaft is of solid cross section. 2. It is fitted to gearbox casing by a ball joint or large spherical bearing to resist torque reaction. 3. It prevents twisting of axle on its springs during power transmission. 4.The diameter of this propeller shaft is small compared to open type. Prepared By:K.Rajesh, AP/Mech,RMKCET
  105. 105. 2. UNIVERSAL JOINTS  Universal joints are used to transmit power between inclined shafts.  Different kinds of universal joints are  Hooks joint  Hooks joint with needle roller bearings  Perfect circle U joints  Flexible Ring universal joints Prepared By:K.Rajesh, AP/Mech,RMKCET
  106. 106.  They are mainly used for making flexible connection between two rigid shaft at an angle.  It is used to connect propeller shaft and gear box during the transmission of rotary motion.  Transmission of power under this varying condition is impossible without using of a flexible device or universal joint.  It consist of two yokes, connected to each end of the shaft.  It does not permit the motion uniformly, if the shafts are operated at an angle. Prepared By:K.Rajesh, AP/Mech,RMKCET
  107. 107. CLASSIFICATION OF UNIVERSAL JOINTS Variable velocity joints Constant velocity joints Prepared By:K.Rajesh, AP/Mech,RMKCET
  108. 108. VARIABLE VELOCITY JOINTS  In this joints the driven and driving shafts do not turn at same speed through each part of revolution is at same speed.  They are further classified into three types: 1. Cross or spider type. 2. Ring type 3. Ball and trunion type. Prepared By:K.Rajesh, AP/Mech,RMKCET
  109. 109. Cross or spider type Ring type Ball and trunion type Prepared By:K.Rajesh, AP/Mech,RMKCET
  110. 110. CONSTANT VELOCITY JOINTS  In this type, the driven shaft and the driving shaft turns at the same speed through each part of the revolution and at the any degree of flex.  This is further classified into three types: 1. Rzeppa . 2. BendixWeiss. 3. Tracta. Prepared By:K.Rajesh, AP/Mech,RMKCET
  111. 111. Rzeppa Bendix Weiss Prepared By:K.Rajesh, AP/Mech,RMKCET
  112. 112. 3. SLIP JOINT  Slip joint is provided to accommodate for the variations of the length of the propeller shaft. This is necessary due to the relative movements of the axle and the vehicle body due to the suspension action.  The slip joint is formed by internal splines on the sleeve and external splines on the propeller shaft. Prepared By:K.Rajesh, AP/Mech,RMKCET
  113. 113. Slip joint figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  114. 114. IMPROVEMENTS in transmission system  Viscous coupling – which responds to the difference in the speed. The torque transmitted depends on the slip between the shafts.  It consist of silicon based oil which thickens on shearing action. It consist of cylindrical chamber of fluid with a stack of perforated rotating discs. The discs are connected alternatively to the inside and outside shaft and chamber. The viscosity of the fluid causes the movement of the discs. Prepared By:K.Rajesh, AP/Mech,RMKCET
  115. 115. Viscous coupling figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  116. 116. DIFFERENTIAL  When a vehicle is negotiating a corner, the outside wheel has to travel a greater distance than the inside wheel. Therefore the outside wheel must turn faster than the inside wheel.  The differential is the device within an axle assembly that differentiates the wheel speed between the two wheels.  The differential also transmits the power from the ring gear to the axle shafts and determine how much power is delivered to each axle. Prepared By:K.Rajesh, AP/Mech,RMKCET
  117. 117. Prepared By:K.Rajesh, AP/Mech,RMKCET
  118. 118. Prepared By:K.Rajesh, AP/Mech,RMKCET
  119. 119. PARTS OF DIFFERENTIAL  Pinion Drive Gear: transfers power from the driveshaft to the ring gear.  Ring Gear: transfers power to the Differential case assembly.  Side/spider gears: help both wheels to turn independently when turning.  Differential case assembly: holds the Ring gear and other components that drive the rear axle.  Rear drive axles: steel shafts that transfer torque from the differential assembly to the drive wheels  Rear axle bearings: ball or roller bearings that fit between the axles and the inside of the axle housing  Axle housing: metal body that encloses and supports parts of the rear axle assembly. Prepared By:K.Rajesh, AP/Mech,RMKCET
  120. 120. ADVANTAGES:  Simple design  Robust and reliable  Few moving parts  Inexpensive to produce DISADVANTAGES:  Supplies equal torque to both wheels APPLICATIONS:  Most production car applications, both cars and trucks CONVENTIONAL DIFFERENTIAL Prepared By:K.Rajesh, AP/Mech,RMKCET
  121. 121. FUNCTIONS  Transfers power from driveshaft to the wheels.  Provides final gear reduction.  Splits amount of torque going to each wheel.  Allow the wheels to rotate at different speeds in turns. Prepared By:K.Rajesh, AP/Mech,RMKCET
  122. 122. TYPES OF DIFFERENTIAL 1. Open or Conventional differential 2. Limited slip differential (LSD) 3. Locking differential 4. AutomaticTorque biasing Prepared By:K.Rajesh, AP/Mech,RMKCET
  123. 123. LIMITED SLIP DIFFERENTIAL  A limited slip differential (LSD) or anti-spin is another type of traction aiding device that uses a mechanical system.  This is activated under centrifugal force to positively lock the left and right spider gears together when one wheel spins a certain amount faster than the other.  This type behaves as an open differential unless one wheel begins to spin and exceeds that threshold.  While positraction units can be of varying strength, some of them with high enough friction to cause an inside tire to spin or outside tire to drag in turns like a spooled differential.  The LSD will remain open unless enough torque is applied to cause one wheel to lose traction and spin, at which point it will engage. Prepared By:K.Rajesh, AP/Mech,RMKCET
  124. 124.  A LSD can use clutches like a posi when engaged, or may also be a solid mechanical connection like a locker or spool. It is called limited slip because it does just that; it limits the amount that one wheel can "slip" (spin). Prepared By:K.Rajesh, AP/Mech,RMKCET
  125. 125. Prepared By:K.Rajesh, AP/Mech,RMKCET
  126. 126. Prepared By:K.Rajesh, AP/Mech,RMKCET
  127. 127. Prepared By:K.Rajesh, AP/Mech,RMKCET
  128. 128. Prepared By:K.Rajesh, AP/Mech,RMKCET
  129. 129. ADVANTAGES:  Manages vehicle traction mechanically  Completely passive system, no user or electrical controller input required DISADVANTAGES:  Many moving components, more susceptible to failure  Expensive to produce APPLICATIONS:  Optional OEM equipment, performance oriented or high end production vehicles  Road racing Prepared By:K.Rajesh, AP/Mech,RMKCET
  130. 130. LOCKING DIFFERENTIAL  A locking differential, such as ones using differential gears in normal use but using air or electrically controlled mechanical system.  It is the one which when locked allow no difference in speed between the two wheels on the axle.  They employ a mechanism for allowing the axles to be locked relative to each other, causing both wheels to turn at the same speed regardless of which has more traction.  This is equivalent to effectively bypassing the differential gears entirely.  Other locking systems may not even use differential gears but instead drive one wheel or both depending on torque value and direction. Prepared By:K.Rajesh, AP/Mech,RMKCET
  131. 131.  Automatic mechanical lockers do allow for some differentiation under certain load conditions, while a selectable locker typically couples both axles with a solid mechanical connection like a spool when engaged. Prepared By:K.Rajesh, AP/Mech,RMKCET
  132. 132. Prepared By:K.Rajesh, AP/Mech,RMKCET
  133. 133. ADVANTAGES:  No moving parts, extremely durable and strong  Maintains constant speed between both wheels  Produces a yaw stabilization force acting through the rear axle, i.e. resists vehicle rotation DISADVANTAGES:  Maintains constant speed between both wheels APPLICATIONS:  Purely off-road vehicles, Drag racing, Oval Racing Prepared By:K.Rajesh, AP/Mech,RMKCET
  134. 134. TORSEN DIFFERENTIAL  A high-friction 'Automatic Torque Biasing' (ATB) differential, such as the Torsen differential, where the friction is between the gear teeth rather than at added clutches.  This applies more torque to the driven road wheel with highest resistance (grip or traction) than is available at the other driven road wheel when the limit of friction is reached at that other wheel.  When tested with the wheels off the ground, if one wheel is rotated with the differential case held, the other wheel will still rotate in the opposite direction as for an open differential.  But there will be some frictional losses and the torque will be distributed at other than 50/50. Although marketed as being "torque-sensing", it functions the same as a limited-slip differential Prepared By:K.Rajesh, AP/Mech,RMKCET
  135. 135.  Shortened from “Torque Sensing” Differential.  Relies on gear pressure angles to cause a mechanical binding in a gear train that resists different wheel speeds.  Non adjustable, and difficult to quantify the performance without expensive equipment.  Has a large performance window, which enables it to be used in a wide range of applications  Still relies on torque input from the wheels to respond and can only apply a ratio of the torque to the non-slipping wheel Prepared By:K.Rajesh, AP/Mech,RMKCET
  136. 136. Prepared By:K.Rajesh, AP/Mech,RMKCET
  137. 137. Prepared By:K.Rajesh, AP/Mech,RMKCET
  138. 138. ACTIVE DIFFERENTIAL  A relatively new technology is the electronically-controlled 'active differential'.  An electronic control unit (ECU) uses inputs from multiple sensors, including yaw rate, steering input angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like understeer.  Active differentials used to play a large role in the World Rally Championship, but in the 2006 season the FIA has limited the use of active differentials only to those drivers who have not competed in the World Rally Championship in the last five years. Prepared By:K.Rajesh, AP/Mech,RMKCET
  139. 139.  Fully integrated active differentials are used on the Ferrari F430, Mitsubishi Lancer Evolution, and on the rear wheels in the Acura RL. A version manufactured by ZF is also being offered on the B8 chassis Audi S4 and Audi A4.  The Volkswagen Golf GTI Mk7 in Performance trim also has an electronically controlled front-axle transverse differential lock, also known asVAQ.  The second constraint of the differential is passive it is actuated by the friction kinematics chain through the ground. The difference in torque on the road wheels and tires (caused by turns or bumpy ground) drives the second degree of freedom, (overcoming the torque of inner friction) to equalize the driving torque on the tires. Prepared By:K.Rajesh, AP/Mech,RMKCET
  140. 140.  The sensitivity of the differential depends on the inner friction through the second degree of freedom. All of the differentials (so called “active” and “passive”) use clutches and brakes for restricting the second degree of freedom, so all suffer from the same disadvantage decreased sensitivity to a dynamically changing environment.  The sensitivity of the ECU controlled differential is also limited by the time delay caused by sensors and the response time of the actuators. Prepared By:K.Rajesh, AP/Mech,RMKCET
  141. 141. Prepared By:K.Rajesh, AP/Mech,RMKCET
  142. 142. REAR AXLE  Rear Axles are structural members on which Rear wheels are mounted on bearings.  The weight of the body of the automobile and load due to the occupants is transmitted through springs to the axle casing. FORCES AND TORQUES ON THE REAR AXLE  Weight of the Body  Driving thrust  Torque Reaction  Side thrust Prepared By:K.Rajesh, AP/Mech,RMKCET
  143. 143. 1.WEIGHT OFTHE BODY  Rear axle behaves like a beam supported at the ends and loaded at two points.  The load coming on the axle is due to the weight of the body being transmitted through the suspension springs.  Weight causes shear force and bending on the wheels. 2. DRIVINGTHRUST  Torque produced by the engine causes the thrust on the wheels. This force is responsible for the forward motion of the vehicle.  The drive force from the wheels is transmitted to the body or chassis by means of Radius rods or thrust members. These members are in longitudinal direction connecting axle casing and the body. Prepared By:K.Rajesh, AP/Mech,RMKCET
  144. 144. 3.TORQUE REACTION  Torque reaction occurs due to the resistance offered by the wheels to the motion. This causes a torque produced on the axle in the counter clockwise direction when viewed from the left side of the vehicle rear wheel axle.  The torque produced by the braking torque is just the opposite to the torque reaction.  The torque reaction is opposed by Panhard rod which connects the Rear axle to the vehicle body or chassis and prevents excessive bending load coming onto the propeller shaft. 4. SIDETHRUST  Side thrust comes mainly when the vehicle is taking a turn or when the vehicle is moving along an laterally inclined surface.  The side thrust coming on to the axle can be taken by Panhard rod. Prepared By:K.Rajesh, AP/Mech,RMKCET
  145. 145. LOADS COMING ONTO LIVE REAR AXLE SHAFT  Shearing force due to vehicle weight  Bending moment due to the offset of the wheel and the suspension.  End thrust due to the side forces due to cornering, side wind etc.  Bending moment due to end thrust and reaction from the tires.  Driving torque. Prepared By:K.Rajesh, AP/Mech,RMKCET
  146. 146. TYPES OF REAR AXLE  DriveAxle  Semi floating axle  Full floating axle  Three quarter floating axle  Dead axle or Lazy axle Prepared By:K.Rajesh, AP/Mech,RMKCET
  147. 147. SEMI-FLOATING AXLE  The wheel hub is connected directly to the rear axle.  All the loads are taken by the rear axle (Shearing, Bending, End thrust, Driving torque and brake torque). ADVANTAGES  The semi floating axle is the simplest and cheapest and they are widely used in cars. DISADVANTAGES  The axle has to be designed for carrying higher loads i.e. they are of higher diameter for the same torque transmitted by other types of axle supporting. Prepared By:K.Rajesh, AP/Mech,RMKCET
  148. 148. Semi floating axlePrepared By:K.Rajesh, AP/Mech,RMKCET
  149. 149. FULL FLOATING AXLE  The wheels hubs are mounted directly onto the axle casing and are supported by two taper roller bearings.  The load on the axle is very less. It need to take only the drive torque. ADVANTAGES  These are very robust type and are used for heavy vehicles.  Axle shaft carry only the drive torque so their failure does not affect the vehicle wheels.  Vehicle can be towed with the broken axle shaft.  Axle shaft can be replaced by without jacking. DISADVANTAGE  Costliest type of axle supporting. Prepared By:K.Rajesh, AP/Mech,RMKCET
  150. 150. Full floating axle Prepared By:K.Rajesh, AP/Mech,RMKCET
  151. 151. THREE QUARTER FLOATING AXLE  The bearing is mounted between the axle and the axle casing.  The axle shaft has to take drive torque and the end loads.  The axle casing will take Bending an shearing forces. ADVANTAGES  At one time this axle type was commonly used for cars and light commercial vehicles. DISADVANTAGES  These axles are no longer preferred. instead semi floating axles are used. Prepared By:K.Rajesh, AP/Mech,RMKCET
  152. 152. Three quarter floating axle figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  153. 153. Prepared By:K.Rajesh, AP/Mech,RMKCET
  154. 154. REAR AXLE DRIVES 1. Hotchkiss Drive 2. Torque tube drive Prepared By:K.Rajesh, AP/Mech,RMKCET
  155. 155. HOTCHKISS DRIVE  Simplest and most widely used rear axle drive.  The suspension springs take torque reaction driving thrust and side thrust  Propeller shaft with two universal joints and a sliding joint. The spring is fixed rigidly in the middle onto the frame. The drive torque is transmitted through the front half of the springs.  The front end of the leaf suspension is rigidly fixed onto the frame while the rear is connected via a shackle.  Two universal joints are used to avoid the bending of the propeller shaft due to the torque reaction.  Sliding joint is provided to accommodate for the variation of the length in the transmission shaft. Prepared By:K.Rajesh, AP/Mech,RMKCET
  156. 156. Prepared By:K.Rajesh, AP/Mech,RMKCET
  157. 157. Prepared By:K.Rajesh, AP/Mech,RMKCET
  158. 158. Hotchkiss drive figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  159. 159. TORQUE TUBE DRIVE  Torque reaction, Braking torque and drive thrust are taken by Torque tube.  The suspension springs are taking only the side thrust and body weight.  One end of the torque tube is attached to the axle casing while the other end is spherical and fits into the cup on the frame. The torque tube encloses the propeller shaft.  Torque tube takes the torque reaction and centre line of the bevel pinion shaft always passes through the centre of the spherical cup.  Single universal joint is used in the transmission drive because the universal joint is situated exactly at the centre of the spherical cup.  No sliding joint is provided since the pinion shaft and the propeller shaft moves same center ( spherical cup). Prepared By:K.Rajesh, AP/Mech,RMKCET
  160. 160. Prepared By:K.Rajesh, AP/Mech,RMKCET
  161. 161. TORQUETUBE DRIVE Prepared By:K.Rajesh, AP/Mech,RMKCET
  162. 162. Torque tube drive figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  163. 163. REAR AXLE CASINGS 1. Split type. 2. Banjo or Separate carrier type. 3. Salisbury or Integral Carrier type. Prepared By:K.Rajesh, AP/Mech,RMKCET
  164. 164. 1. SPLIT TYPE  The axle casing is made in two halves and then bolted together for assembly. But the main disadvantage is whole rear axle has to be removed as a unit and reassembled in case of a fault. This kind is no longer used now. Prepared By:K.Rajesh, AP/Mech,RMKCET
  165. 165. 2. BANJO OR SEPARATE CARRIER  Axle is made as a single piece The complete differential unit is separate unit and is bolted to the axle casing and the two shafts are put from two sides.  In case of repair the shafts can be taken from two sides and differential can be removed easily. Prepared By:K.Rajesh, AP/Mech,RMKCET
  166. 166. 3. SALISBURY OR INTERGRAL CARRIER TYPE  This is similar to the banjo type except that the permanent housing tubes are pressed and welded onto the sides.  This is the most commonly used kind of rear wheel driven cars. Prepared By:K.Rajesh, AP/Mech,RMKCET
  167. 167. Final drive • Final drive is used to provide a permamanent speed reduction and to turn the drive through 90 degree. • The reduction ratio provided by the final drive is 4:1 for cars and 10:1 for heavy vehicles. • The reduction ration upto 7:1 can be done in single stage and above that is done in two stages.This is done to reduce the size of the gear and to improve the ground clearance. • Final drive can be bevel pinion and crown wheel or worm and worm wheel arrangement. Prepared By:K.Rajesh, AP/Mech,RMKCET
  168. 168. TYPES OF GEARS FOR FINAL DRIVE 1. Straight Bevel Gears. 2. Spiral Bevel Gears. 3. Hypoid Bevel Gears 4. Worm andWormWheel Arrangement. Prepared By:K.Rajesh, AP/Mech,RMKCET
  169. 169. 1. Straight bevel gears • The gears have straight teeth. • Advantages • Simplest and Cheapest • Disadvantages • Uneven transmission due to contact of single pair of teeth. • Less load carrying capacity. • Noisy and high levels of wear. Prepared By:K.Rajesh, AP/Mech,RMKCET
  170. 170. Straight bevel gears Prepared By:K.Rajesh, AP/Mech,RMKCET
  171. 171. 2. Spiral bevel gears • Spiral bevel gears have curved teeth so have greater number of teeth in contact.The gear tooth have sliding motion also in between. • Advantages • Silent Running. • They are able to take more loads. Prepared By:K.Rajesh, AP/Mech,RMKCET
  172. 172. Spiral bevel gears figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  173. 173. 3. Hypoid gears • The structure of the teeth have hyperboloid in shape. Hyperboloid is obtained by rotating a hyperbolaAbut an offset axis. • The gears transmit motion at right at right angles but the axis of the gears don’t intersect but they lie at an offset distance. • Advantages • The hypoid gears permit a lower position of the propeller shaft and allow more lower chassis height or less chassis height as the case may be. • Hypoid gears increases the loads capacity of the gears. • Disadvantage • Expensive difficult to assemble and need special lubricant due to the greater sliding action between the gears. Prepared By:K.Rajesh, AP/Mech,RMKCET
  174. 174. Hypoid gears figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  175. 175. 4. Worm and worm wheel • Worm is a single or multi started thread which drives the worm wheel which has teeth over the periphery of the wheel. • Higher gear ratios are possible in worm and worm wheel arrangement. • Advantages • Worm andWorm wheel arrangement is particularly used in heavy vehicle where higher gear ratios of greater than 6 needed • Strong and efficient drive • Single stage reduction is only necessary for higher gear ratios also. • Worm gears give low chassis height or more ground clearance as the case may be. • Disadvantages • Higher cost and more weight than bevel gear • Mechanical efficiency is lower than bevel gear for single stage reduction • Lubrication is difficult with overhead worm. Prepared By:K.Rajesh, AP/Mech,RMKCET
  176. 176. Worm and worm wheel Figure Prepared By:K.Rajesh, AP/Mech,RMKCET
  177. 177. Thank you Prepared By:K.Rajesh, AP/Mech,RMKCET

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