Automobile Engineering TRANSMISSION SYSTEMS

Details of Faculty Mr.Y.Sureshbabu,ME,(Phd),PDAuE,MISTE Course PPT Prepared by: Mr.Y.Sureshbabu,ME,(Phd),PDAuE,MISTE Assistant Professor Department of Mechanical Engineering Sri Eshwar College of Engineering

Transmission system It is a system by means of which power developed by the engine is transmitted to the road wheels to propel the vehicle

Purpose of transmission system To transmit the power from engine to rear wheel smoothly without vibration. It enables the reduction of wheel speed at different load condition.

Components of transmission system Clutch Gear box Slip joint Universal joint Propeller shaft Final drive Differential unit Rear axle

Components of transmission system

Clutch clutch is a mechanism which enables the rotary motion of one shaft to be transmitted at will to second shaft

Clutch Clutch is device which is used to connect or disconnect the engine from the rest of transmission elements It is located between engine and gear box

Purpose of the Clutch Allows engine to be disengaged from transmission for shifting gears and coming to a stop Allows smooth engagement of engine to transmission VHS AUTO 12/2001

Functions of clutch To transmit the power from engine to rear wheel smoothly without jerking or shock It is used to connect or disconnect the power Whenever the required time (gear Shifting time)

Types of clutch 1.Friction clutch (i) single plate (ii) Multi plate (iii) cone clutch 2.centrifugalclutch 3. fluid flywheel

Friction Clutches A clutch enables two co-axial shafts to be engaged or disengaged while at rest or in relative motion.

Types of Friction Clutches Disc or plate clutches Cone clutches Centrifugal clutches

Single plate clutch (or) diaphragm clutch

Clutch Linkage

Clutch components Flywheel – mounts to the engine crankshaft Clutch Disk – the friction material assembly that provides easy engagement and firm torque transference Pressure Plate – also known as “Clutch Cover” – this is the spring-loaded surface that locks the clutch Throw-out Bearing – also known as “Release Bearing” Pilot bearing –centers and supports the transmission input shaft Clutch Cable – mechanical release mechanism for some vehicles Clutch Master Cylinder – force-multiplying cylinder for vehicles with hydraulic release mechanisms Clutch Slave Cylinder – used along with a Master Cylinder for hydraulic release mechanisms

Clutch plate or friction plate Torsional springs Friction lining Splined boss (hub)

Pressure plate and housing Clutch housing Diaphragm spring Pressure plate

Clutch housing It is mounted on the flywheel Flywheel is mounted on crank shaft VHS AUTO 12/2001

Clutches Splines to input shaft Of transmission Clutch Disk or 44-3 Construction of the Clutch Clutch Disk or Friction Disk VHS AUTO 12/2001

Pilot Bushing or bearing 12/2001

Clutches Flywheel bolts to crankshaft Pressure plate & cover bolt to flywheel Flywheel bolts to crankshaft When unbolting pressure plate from the flywheel, remove bolts evenly as not to bend the cover. REMEMBER, this is under high spring pressure. If there is a chance you will be reusing pressure plate, make alignment marks to flywheel to maintain proper balance BEFORE removal VHS AUTO 12/2001

Single plate clutch

Single-plate Friction Clutch (Disengaged position) Flat-plate friction clutches Friction plate springs W Driven shaft W (axial thrust) Driving shaft T T Friction lining Pressure plates Single-plate Friction Clutch (Disengaged position)

Single-plate Friction Clutch (Engaged position) Flat-plate friction clutches T W (axial thrust) W Friction plate Friction lining Pressure plates springs Driving shaft Driven shaft Single-plate Friction Clutch (Engaged position)

Multi plate clutches In a multi plate clutch, the torque is transmitted by friction between several pairs of co-axial annular driving faces maintained in contact by an axial thrust. Both sides of each plate are lined with friction material, so that a single-plate clutch has two pairs of driving faces in contact.

Multiple plate friction clutch This type of clutch has several driving members interleaved with several driven members. It is used in motorcycles, automatic transmissions and in some diesel locomotives with mechanical transmission. It is also used in some electronically controlled all-wheel drive systems. It is the most common type of clutch on modern types of vehicles.

Multi plate clutches n = no. of pairs of driving faces. Then, for a plate clutch, the maximum torque transmitted is

Multi plate clutch driver driven No. of driving pairs n = 6 Pressure plates Friction plates 2 1 4 3 6 5 No. of driving pairs n = 6

Cone clutch α = semi-apex angle of the cone w T = μWrm cosecα Only one pair of driving surfaces is possible, n =1 α w Driving shaft Driven shaft Friction lining The maximum torque transmitted = T = μWrm cosecα

2.Centrifugal clutch F=mrω2 ω Driven shaft Driving shaft Friction lining Total friction torque , T = nµR(F-P) F=mrω2 ω P R

3.Fluid flywheel

Fluid flywheel The torque converter is a device which multiplies the engine torque and also serves as automatic clutch to transfer the engine torque to the transmission. The torque converter also functions like a fluid coupling. There are three basic parts of torque converter 1.Stator 2.Rotor (also called turbine runner) and 3.Impeller

Fluid flywheel The impeller is directly connected to the engine crankshaft and starts rotating as soon as the engine starts. The impeller has vanes on its inner side and is filled with fluid. The turbine runner is connected to the transmission input shaft. The stator is a device which is located between impeller and turbine runner and it is mounted on the one way clutch so as to provide the rotation in one direction only. When the engine starts, the fluid inside the impeller starts rotating and as the speed increases it starts flowing outwards on the vane surface due to centrifugal force. Due to this high force, the fluid moves towards the runner and strikes its vanes causing it to rotate in the same direction. This rotates the transmission input shaft. The fluid in the turbine hits the vanes of stator which causes the fluid to hit the vanes of impeller again and the cycle repeats. This function of stator causes the generation of torque to approximately three times the normal transmission.

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