What is an Automotive Clutch?
The meaning of clutch is to hold on to or grab or grip something. The automotive clutch is a device that engages and disengages the drive between two moving mechanisms or assemblies such as a gear box. One of them consists of the driving gears while the other has driven gears.
However, the driving gears get the engine's rotating motion while the driven gears rotate the wheels. An automotive clutch connects/disconnects the engine with the gearbox that rotates at different speeds than the engine. It allows the smooth shifting of gears by disengaging and re-engaging the engine from the gearbox when the vehicle is in motion.
The clutch ‘engages’ when it connects the two rotating shafts so that they are locked together. Thus, they become one unit and spin at the same speed. It ‘disengages’ when the shafts are unlocked (not locked) and spin at different speeds. However, the clutch is said to be ‘slipping’ when the shafts are still locked together, but they spin at different speeds.
In other words, the automotive clutch engages and disengages the power transmission to the gearbox while shifting the gears either accelerates or slows down the vehicle. Thus, it avoids the friction between the driving and driven gears being engaged/disengaged. It also prevents any damage to the gears. Generally, vehicles with manual gearboxes have a single clutch. However, automatic transmission vehicles could have more than one clutch.
Characteristics of automotive clutch:
The automotive clutch must possess the following qualities:
- Transmission of torque – It should be capable of transmitting the maximum engine torque.
- Gradual engagement – It should engage/disengage gradually and positively without any jerks/shocks.
- Dissipation of heat – Operation of clutch generates a large amount of heat. Hence, the clutch should ensure sufficient heat dissipation.
- Dynamically balanced – It must be dynamically balanced, especially in high-speed vehicles.
- Damping of vibrations – It must have a suitable mechanism for damping the vibrations and eliminating noise during transmission.
- Compact size – It must be of the smallest size and occupy a minimum amount of space.
- Free pedal play – It must have provision for the pedal play to reduce the effective clamping load on the thrust bearing and also its wear & tear.
- Ease of operation – It must offer an effortless/smooth operation of engagement/disengagement for the driver.
Typically, the basic clutch mechanism consists of a driven plate (or clutch plate), which has a splined hub at the center. It slides onto the gearbox’s driveshaft and presses against the engine’s flywheel. The clutch pedal performs the clutch operation with the help of a set of levers. It releases the driven plate, which gets pushed away from the flywheel. This occurs when the engine connects to the wheels. On the other hand, the pressure plate presses the driven plate against the flywheel. It consists of either several coil springs or a cone-shaped single diaphragm spring.