CRUTCH AND HOW IT OPERATES
The car’s transmission takes power from the to the road wheels. On a front-engine rear-wheel-drive it consists of a or a torque converter fixed to the flywheel, then a , propeller shaft and final drive unit which splits the output in half, to drive each rear wheel.
Some dispense with the propeller shaft by combining the and transmission into one power pack and mounting it between the driving wheels. This arrangement needs only two drive shaft to transmit power to the wheels.
The disconnects the from the road wheels when the driver is changing or bringing the to a stop. The action can be likened to the operation of a sanding disc on a power drill. If this is rotated and brought face-to-face with a separate stationary sanding disc, as the two faces meet the initial frictional contact will make the second disc turn slowly but as pressure is increased, both discs will turn at the same speed.
On a car engine, the same effect is achieved by sandwiching a friction-lined disc i.e. the driven plate which is attached to the gearbox input shaft between a pressure plate and the flywheel face. The pressure plate is connected to a cover bolted to the flywheel. Operating the pedal moves the pressure plate away from the flywheel, and the driven plate between them can rotate independently. When the driver lifts his foot off the pedal, the pressure plate moves towards the flywheel again, clamping the driven plate and the shaft to the flywheel.
Although it is possible to slip the by partial operation of the pedal, it is essential that the does not slip when the pedal is fully released. On most , the clamping load is applied by a powerful diaphragm spring, i.e. a cone of spring steel that is fitted so that at rest its outer rim pushes the pressure plate toward the flywheel.
Operating the pedal moves a thrust bearing against the center of the diaphragm, causing it to dish away from the flywheel, thus releasing the clamping load on the pressure plate. Before diaphragm springs became available, a circle of coil springs bearing on the rear face of the pressure plate applied the clamping load.
HOW THE PEDAL IS LINKED TO THE
The is operated either hydraulically or by a cable. On a cable system, a flexible cable is routed from the pedal through the bulkhead of the compartment and runs down the side of the to a clutch-operating lever. At one end of the cable, there are adjusting nuts to compensate for any cable stretching.
systems have a master cylinder connected to the pedal, attached by a pipe to a slave cylinder which is joined to the clutch-operating lever.
CAR GEARBOX AND THE ARRANGEMENT
Because the produces very little power at low speeds, it cannot be directly linked to the road wheels and must, therefore, be geared down. At 70mph, for instance, most small have their running at about 4000 revolutions per minute while the road wheels are turning at about 1,000rpm. The gearing-down is achieved by reduction in the final drive, and if the traveled constantly at 70mph, this is all that would be needed. However, besides on motorways, the must be able to start from a standstill and tackle steep hills. In order to keep the working at its most efficient speed under all conditions, all have a . The most popular type is a manual which offers four choices of the ratio.
ratios are determined by the number of teeth on meshing wheels. If a wheel with 12 teeth is meshed with a wheel having 24 teeth, the smaller must rotate twice to turn the bigger once and the ratio of these two would be 2:1. The final drive that reduces 4,000rpm at the heels has a ratio 4:1.
To move it from a standstill, the average small has a bottom ratio of around 3.5:1. Other typical ratios are about 2:1 in second , 1.4:1 in third and 1:1 in top. All these are in addition to the final-drive ratio, so with a pressing, the pedal forces fluid into the slave cylinder which operates the .
Originally posted 2018-08-09 11:35:58.
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