Why and how do car clutches work?


I’ll appreciate any links to further reading. Currently going through its Wikipedia page but I’m not an engineer so hard for me to take so much info at once.

In: Engineering

I would suggest you to look on YouTube as there are loads of videos explaining it in detail and showing actual clutches and gearboxes in action.

The US Auto Industry channel presents really good videos; look up “Spinning Levers – How a transmission works (1936)”

Basically there is it the flywheel which is spinning at the speed of the engine. When the clutch pedal is not depressed this is being sandwiched against the friction plate. The friction plate is basically a plate with abrasives on it, like sandpaper. So when they are squeezed together hard enough they turn as one but when you are letting the clutch out slowly, some slipping it allowed to let the car accelerate smoothly. On the other side of the sandwich is the pressure plate. This is the part that lets the clutch pedal control how tightly the friction plate is being squeezed. There is a special “diaphragm spring” in the middle of a circular metal plate. It works in such a way that when you push the clutch pedal down. The pressure plate backs away from the friction plate and all three parts are spinning independently but when you let the clutch out, they spin together.

This is why it’s important to downshift with Rev-matching. It lets all three components come NM up to the same speed before they’re engaged and makes your clutch last longer. Some people double clutch downshift, I personally don’t.