How Do Wet Clutches Work?

A wet clutch is one that is soaked in oil, as opposed to having no oil in the parts. It has a series of plates called drive plates, engaged in a basket to apply drive to the vehicle. A wet clutch consists of a series of discs inside a cage or the clutch basket. Each drive plate has notches on the end of it that fit in the slots in the clutch basket or cage. The pressure plate assembly, which includes the drive plates and discs, slides into the the cage to engage it. Since the clutch basket is connected to the drive chain, this puts the vehicle into drive.

In the drive plate assembly, only some of the plates are always spinning, even though this is connected to the engine all the time. The friction plates are what actually apply the leverage to get the vehicle moving. When these squeeze together, it engages the clutch, and all the discs start moving together. This includes the notched drive discs, which come in contact with the clutch basket.

The drive plate actually looks like a stack of pancakes with one friction plate, one driving plate, one friction plate, etc., stacked one on top of another. It is is held together by springs and screws called drive screws, which apply the pressure to the plates, and this needs oil to operate properly.

This whole mechanism is soaked in oil because of the amount of friction involved in its operation. In a dry clutch, there is no oil in the mechanism. It is an assembly of dry plates that operates on friction. A wet clutch uses the friction component of the oil between the drive plates to allow the plates to slide past each other and for proper operation.