An important add-on for your PTO or power take-off is an overrun clutch. The PTO overrun clutch is basically a ratcheting mechanism. It locks in one direction and ratchets like a freewheel on a bicycle wheel in the other direction. This allows a rotary implement like a mower to overrun your PTO shaft, hence the name. We always equip all of our tractors with this device. It slides right onto your PTO shaft and locks into place. It functions similar to a ratchet on a bicycle wheel. The purpose of the overrun clutch is to allow an implement like a mower, which carries a lot of momentum, to keep spinning even when you press the clutch and stop the tractor. This happens because the momentum of the blades turning keeps the drive shaft and PTO spinning, thereby turning the transmission and pushing the tractor forward. This is an important safety feature. When you want to stop quickly to avoid running into something, you don't want a rotary implement like a mower pushing the tractor forward. The PTO overrun clutch prevents that from happening.