How a clutch works...

[InfernalVortex]

Can someone explain to me in layman's terms exactly how a clutch works?

I know it works based on friction and connects the flywheel to the drivetrain, etc... but I've got THIS:



The flywheel is attached to the engine.

The clutch disk is between the flywheel and... taht other thing? What is it? THe pressure plate?

So when I step on the clutch pedal, the clutch disk disengages from the flywheel. That's fine, makes plenty of sense. But if it's all about the clutch mating with the flywheel, then wtf is the point of the friction surface on the pressure plate?

And when you let off the clutch pedal, what's holding the clutch disk against the flywheel? I'll assume the pressure plate (due to it's name) is doing the work... but what provides the force? Is that what the little fingers in the center of it are for? The metal bends or something and just holds it?

But if it's strong enough to couple it all together, then how come I can disengage it with just a pedal and my foot? Is the clutch hydraulic system vacuum assisted by any chance like the brake system is?

And then I'm thinking, if the pressure plate is the part that holds the clutch disk against the flywheel... then why is there a clutch disk? Why is there a middle man to this operation?


I know there's an obvious and logical reason to all of this, but I just need some things clarified!

[Viper007Bond]

Yeah, the one with the slits in it is the pressure plate I believe which is basically a flat spring. It holds the clutch against the disc.

The clutch pedal works the same kinda way a pulley does. You push the clutch a long way, but due to hydraulic cylinder sizes, the plate only moves just a little bit. That way you can overcome the strong spring.

The brakes and clutch are on totally different "circuits", but they work similarly (long, easy pedal converts to short, hard movement).


http://en.wikipedia.org/wiki/Clutch

[scathing]

Originally Posted by InfernalVortex

So when I step on the clutch pedal, the clutch disk disengages from the flywheel. That's fine, makes plenty of sense. But if it's all about the clutch mating with the flywheel, then wtf is the point of the friction surface on the pressure plate?

As always, How Stuff Works has the hookup.

http://auto.howstuffworks.com/clutch.htm

[InfernalVortex]

Originally Posted by scathing

As always, How Stuff Works has the hookup.

http://auto.howstuffworks.com/clutch.htm

Not nearly as specific as I'm wanting. WHat makes it worse is that my particular clutch setup is some sort of reverse-pull system of some sort. Weird...

[bone]

Originally Posted by InfernalVortex

And when you let off the clutch pedal, what's holding the clutch disk against the flywheel? I'll assume the pressure plate (due to it's name) is doing the work... but what provides the force? Is that what the little fingers in the center of it are for? The metal bends or something and just holds it?

i'll reuse viper's image, since it's a good one

the pressure plate just presses the clutch disc against the flywheel
the plate spring does the work. it's metal disc with big teeth facing inwards and made of some sort of material so it flexes. when free the outer disc presses the pressure plate against the clutch disc. but when you press in all the teeth at once (what the thrust bearing does) it pops over, and all pressure is gone

NEVER press only one teeth in, the plate spring will brake. if you wanne test it, take an old bearing and push in all teeth at the same time with that