Power Transfer Unit: Notes
The Power Transfer Unit (PTU) is a gearbox that attaches to the transmission. The PTU directs power from the transmission differential case through a dog clutch to a hypoid ring gear. A hypoid pinion gear is meshed to the ring gear and splined to the output flange. A dog clutch is used to transfer drive torque from the input shaft to the ring gear. When the dog clutch is released, no torque is transferred through the ring gear and pinion to the rear driveshaft. When the dog clutch is engaged, normal AWD function is achieved by directing torque to the rear wheels as needed to prevent or control wheel slip and improve handling.