MVE Chap 3 Power - 3 POWER TRAIN/DRIVR TRAIN In a vehicle the mechanism that transmits the power developed by the engine to the wheels is called

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1 3. POWER TRAIN/DRIVR TRAIN In a vehicle, the mechanism that transmits the power developed by the engine to the wheels is called the power train. The power train serves two functions: it transmits power from the engine to the drive wheels, and it varies the amount of speed and torque. There are commonly two sets of gears in the power train, the transmission and the differential. The transmission provides a means for changing the speed and torque of the engine before it reaches to the driving wheels to best meet each particular driving situation. Manual transmissions require use of a clutch to apply and remove engine torque to the transmission input shaft as needed by the driver. The drive shaft, or propeller shaft, connects the transmission output shaft to the differential pinion shaft. When a car makes a turn, the outer wheel has to turn faster than the inner wheel, due to the difference in the length of the paths they take. The differential lets the outer and inner wheels to turn at different speeds. Some types of power train lay outs use a "Transaxle", which is simply a combination of the transmission and the differential. These are usually found on front wheel drive cars, but are also used on mid- and rear-engine cars. Fig Power train component DRIVE ARRENGMENTS : (2WD, 4WD) 2WD (2-Wheel Drive) The rotating motion produced by the crankshaft at the front of the vehicle is transmitted either to the two wheels at the rear (rear wheel drive) (FR), or the two wheels at the front (front wheel drive) (FF). Some cars are manufactured with rear-mounted engines (RR).
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2 FF drive FR drive RR drive Part time 4 Wheel Drive 4-wheel drive vehicles use live front and rear drive axles. When the front drive axle receives power from the transfer case, along with the rear drive axle, the vehicle can function well on off-road terrain (sand, rocks, mud, snow, etc.). A part time 4-wheel drive vehicle has one drive axle that is automatically in use. The operator of the vehicle has to activate and deactivate the second live drive axle . 4-Wheel drive Full time 4 Wheel drive A full time 4-wheel drive vehicle has both axles live at all times without manually activating or deactivating axles. 3.1 CLUTCH The clutch is located between the engine and the transmission/transaxle as shown below. An automotive clutch is used to connect/engage and disconnect/disengage the engine and manual (hand-shifted) transmission or transaxle, both starting up and during gear shifting . A friction type of clutch is used in motor vehicles with manually operated transmission or transaxle.
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3 A manual clutch works on the principle of friction. Its function depends upon sufficient friction being developed between the contact surfaces of two or more members to transmit the desired torque. Clutch capacity (The ability of a friction clutch to transmit torque) depends on the following factors:
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This note was uploaded on 12/16/2011 for the course MENG 5165 taught by Professor Shewangizaw during the Spring '11 term at Cornell University (Engineering School).

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MVE Chap 3 Power - 3 POWER TRAIN/DRIVR TRAIN In a vehicle the mechanism that transmits the power developed by the engine to the wheels is called

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