Basics of a clutch - back of the book

Clutch basics

What is the clutch? A clutch is a component of the manual transmission that allows the driver to apply variable amounts of energy from the engine to the transmission.  This is important, as the car cannot be driven with an on and off position of the transmission connected to the engine power.  It allows the car to take off with ease and disconnect the transmission from the engine.

The clutch is located in the bell-housing and sits on top of the flywheel.  It is made up of the clutch disc, pressure plate and the release/thrust bearing. The clutch works fairly similar to the brake calliper and rotor system,  the clutch uses friction to connect the engine power to the transmission.  Like the brake pads and rotors, these contact points can wear down, and need to be replaced around every 100,000km of travelling.

Here is what the components of a typical road clutch looks like:

[pic]

the clutch disc sits inside the pressure plate, and the pressure plate is bolted into the flywheel.  The input shaft of the transmission is inserted into the clutch disc, and the pressure plate is controlled by the clutch pedal, allowing it to apply different amounts of pressure to the clutch disc to the flywheel.  When the clutch disc is in full contact with the flywheel, the engines power is moved located directly to the transmission, and eventually the wheels.

The pressure is applied to clutch disc by the pressure of the pressure plate, unless the clutch pedal is pressed.  The pedal releases this pressure and disconnected the transmission from the transmission.  This diagram shows a clutch applied (left) and the clutch disconnected (right).

Today, we tested the cutch in action.  We pressed the clutch pressure plate in as if it were installed in a car.  The hydraulic press was pressed against the diaphragm and the clutch disc was released.  When we pressed the pressure plate down, we could actually rotate the clutch disc inside.  This means that when the clutch is released (pedal down), the clutch disc, which is connected to the input shaft, is completely disconnected from the flywheel, which is connected to the crank shaft. 

But of course, there are different types of clutches.  Aside from all the high performance after-market clutches available out there, there is the coil-spring clutch, which works in a similar way, but instead of a diaphragm acting as the spring pressure of the clutch pressure being forced, that pressure is applied through a group of coils, which sits between the pressure plate and the clutch disc.

here is a diagram showing the coil-spring clutch:

                                                                                           

Servicing clutches

Servicing clutches must be taken very seriously, they are very expensive, fairly sophisticated and have few potentials of failure after the installation.  Professionalism must be taken seriously and precautions must be considered.  Guarantees must be met in order for a successful service.  This means that additions to the installation including skimming the flywheel properly, etc, should be done, for guarantee purposes.

A clutch job can be a big job, as it involves removing, or at least, disconnecting the transmission from the engine.  This means that, doing this job wrong, can cost you plenty of time as re-doing the process will take long, so make sure to do the job correctly and as best as you can do it the first time.

as usual, when doing a repair/service, take a visual inspection.  A visual inspection won't cost much and can mean a lot in the future.

any cables or parts that seem to have the potential to fail in the future, are worth repairing or replacing now, as a job that requires pulling apart the transmission can cost a lot. 

I will finish this blog entry tomorrow so bye for now =)