An Electromagnetic clutch, commonly called a power takeoff clutch (PTO), is the part of a or riding tractor responsible for engaging the blade.

The Electromagnetic clutch helps to transfer engine power to the drive train. The clutch connects two drive shafts and is controlled by a toggle switch. PTO clutches work in conjunction with the PTO drive shaft and must be compatible with the transmission of the Auto.

An Electromagnetic clutch gets energy from the mower's engine and transfers it to the blade. An electric clutch also performs the function of a brake to stop the blades when the PTO gets turned off.

Some manufacturers suggest the purchase of a PTO over running clutch. This type of clutch prevents the mower from moving after the driver disengages the Auto clutch.