Automobile clutch works

  Automobile clutch

The automobile drivetrain carries power from the engine to the drive wheels. In-vehicle with a manual transmission or manual transaxle (Gearbox). The power flows through a clutch. This device engages and disengages the manual transmission and transaxle and the engine power.

The purpose of the clutch

The clutch is an important part of the transmission system. It transmits engine power to the gearbox at various speeds. The clutch is to temporarily disconnect the gearbox unit when the gear has to be shifted to first to second and other gears in the manual gearbox. It also used for a slowdown vehicle and complete stop, without turning off the engine.

The clutch is located between the gearbox (transmission) and the engine.

Types of automobile clutch

Generally when we talk about types of clutch most common clutch used in heavy-duty vehicle and light-duty passengers car is the friction type of clutch with a single plate dry clutch. Expect a two-wheeler motorcycle and scooter. And another type of automobile clutch is fluid coupling ( fluid flywheel).

The friction type of single plate clutch 

The friction type of single-plate dry clutch work on the fact that friction is caused when two rotating discs or two driving members namely the flywheel and pressure disc come into contact with each other.

Fluid coupling (Fluid flywheel) work on the transfer of energy from one rotor to the other by some fluid. It works exactly Like a torque converter. This kind of clutch mechanism uses on the automatic gearbox (transmission).

Construction and operation of the single-plate dry clutch.

The typical clutch consists of three parts these are the engine flywheel, a clutch plate (friction plate) and a pressure plate(disc). The flywheel and pressure disc is the drive or driving member. They attached to the end rotate with the engine crankshaft.

When the driver pushes the clutch pedal down the clutch disengage or disconnects from the engine flywheel.No engine power can flow through to the gearbox (transmission or transaxle). When the driver releases the clutch pedal, the clutch engages (connects). This allows power to flow through.

Components of clutch

Components of the friction plate dry single-plate clutch are clutch plate ( friction plate), pressure disc/plate, release bearing and clutch linkage whether mechanically or hydraulically operated.

Clutch plate (friction plate)

In the clutch, a flat disc faced on both side with friction materials and splined to the clutch shaft positioned between the clutch pressure plate and engine flywheel. It Also called a friction disc.

Pressure plate (pressure disc)

A spring-loaded metal plate mounted on and rotating therewith the flywheel that holds the clutch plate against the flywheel. This keeps the engine and manual gearboxes coupled.it also provides cushioning spring in the clutch plate to reduce jerky start.

Release Bearing (Throwout bearing)

In the clitch, the bearing that pushes or pulls the pressure plate/disc release lever or fingers in or out disengages the engine from the gearbox (transmission) when the driver depresses the clutch pedal. It also called throw out bearing.

Clutch linkage 

The part that connects the clutch pedal to the release bearing makes up the clutch linkage. It is either mechanically (rod or cable)  and hydraulically operated. They all convert a light force applied to the clutch pedal into a greatly increased force that moves the release bearing.

Hydraulic clutch linkage 

The operation of the hydraulic clutch linkage begins when the driver depresses the clutch pedal. This forces a pushrod into the clutch master cylinder pressurized fluid is then forced from the master cylinder, through is hydraulic line to the slave cylinder. A slave cylinder is a device that converts hydraulic pressure to mechanical movement. The pressurised fluid then pushes a piston and pushrod out of the slave cylinder. The pushrod movement operates the clutch fork and disengages (discounts) the clutch.  

 Concentric slave cylinder (CSC) or Clutch Concentric Cylinder.

Nowadays, all modern vehicles adopted a Concentric Slave Cylinder (CSC) or Clutch Concentric Cylinder, which is the same function does base on a hydraulic clutch linkage system in the manual gearbox. A hydraulic clutch linkage system clutch actuator in the form of a slave/ concentric cylinder.

Clutch slave cylinder comprised of the hydraulic lines, slave cylinder and concentric cylinder in the combines with a single unit or single component. There is no need for separate parts like clutch fork, release bearing, holder, it all comes on a single component called concentric slave cylinder or clutch concentric cylinder. So that is a more compact and more effective function and less foot effort is required to operate the clutch pedal. This Clutch slave cylinder provides for smooth gearing change and self-adjusting only given bleeding nipple is the outer side of the transmission housing (if required). 

How does concentric slave cylinder work?

When the clutch pedal depresses, the clutch master cylinder sends hydraulic fluid that generated hydraulic pressure with hose lines to the clutch slave cylinder which connect with the clutch actuator concentric unit, on that way clutches action is work in the manual gearbox ( transmission). It works engages (connects) and disengages (disconnects) the engine power to the road wheels.

This concentric slave cylinder gets more advantage over the traditional cable linkage system.

• it a simple and compact system.
• It Self adjusting and easy operation.
• Heat resistance
• Less foot effort
• Longer service life
• Overall weight reduced (due to fewer components).
• It provides for smooth gear shifting.

One major trouble on this concentric slave cylinder is the Clutch pedal sinking it may due to the clutch concentric unit leakages and leakage of the hydraulic circuit. The only remedies we need to replace the clutch concentric unit and clutch overhaul service.

The features of a good quality clutch

• A good quality clutch should 
• It should be easily operated. 
• It should require minimal physical effort to disengage.
• It should not slip when engaged.
• Its operation should be noiseless.
• It should pose maximum torque capacity.
• Need least pedal pressure to function.
• Pick up the load without any noise.
• Have the capacity to damp out vibration.
• It should have simple means of its adjustments.
• It should be easily accessible.

Troubleshooting of clutch assembly

There is some main possible trouble with friction type dry single-plate clutch assembly.  They are clutch slippage or slip, Clutch drag Clutch noise these are mainly noticeable when you drive the vehicle.

Clutch slippage (clutch slip)

Any increase in engine speed at the same vehicle speed is referred to as slippage of the clutch.

The main causes for the clutch slippage may be due to - 

Incorrectly adjusted linkage and lever.

Worn out the clutch plate ( friction disc).

Weak pressure plate ( pressure disc).

Oil or grease on the plate or disc.

Broken return spring.

Clutch drag 

If the clutch is not disengaging fully and( in motion).

• Worn out transmission bearing, shifting heart fast (in neutral).
• Loose friction disc hub on the clutch shaft ( while engaging).
• Worn throwout bearing or poor lubrication ( while disengaging).
• The pilot bearing or bushing, gearbox input shaft bearing can all make noise.

Clutch Noise

 Any noise in the clutch may be due to -

• The dry or dirty linkage pivot point (in motion).
• Hydraulic fluid leakage or clutch concentric slave cylinder leaking.
• Worn out transmission bearing, shifting gear to fast ( in neutral ).
• Loose friction disc hub on the clutch shaft (while engaging).
• Worn throwout bearing or poor lubrication(while disengaging).
• The pilot bearing or bushing, release bearing and transmission (gearbox) input shaft bearing can all make noise.