Clutch

From Quad Hub Wiki

A clutch is a mechanism for transmitting rotation, which can be engaged and disengaged.

In most ATVs, the clutch is operated by the clutch lever, located on the left handlebar. No pressure on the lever means that the clutch plates are engaged (driving), while pulling the lever back towards the rider will disengage the clutch plates, allowing the rider to shift gears. ATV clutches are usually made up of a stack of alternating plain steel and friction plates. One type of plate has lugs on its inner diameter that key it to the engine crankshaft, while the other type of plate has lugs on its outer diameter that key it to a basket that turns the transmission input shaft. The plates are forced together by a set of coil springs when the clutch is engaged.

When engaging the clutch, the engine speed may need to be increased from idle using the throttle so that the engine does not stall. However, raising the engine speed too high while engaging the clutch will cause excessive clutch plate wear. Engaging the clutch abruptly when the engine is turning at high speed causes a harsh, jerky start. This kind of start is necessary and desirable in drag racing and other competitions where speed is more of an issue than comfort.

Wet and Dry

A wet clutch is immersed in a cooling lubricating fluid, which also keeps the surfaces clean and gives smoother performance and longer life. Wet clutches, however, tend to lose some energy to the liquid. A dry clutch, as the name implies, is not bathed in fluid. Since the surfaces of a wet clutch can be slippery (as with a ATV clutch bathed in oil), stacking multiple clutch disks can compensate for the lower coefficient of friction and so eliminate slippage when fully engaged.