Overdrive One-Way Clutch (OWC) Mechanical Diode: Notes

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

The overdrive OWC mechanical diode is a OWC which also acts as the coast clutch pressure plate. It provides direct drive through the overdrive gearset when in power ON mode. It overruns in power OFF mode or when the overdrive clutch is applied.

Engine torque is transmitted in 1st, 3rd and 5th gears while the selector lever is in the Overdrive (Circle D) position. The input shaft drives the overdrive carrier clockwise. The overdrive carrier has the coast clutch hub bolted to it which also turns clockwise. The overdrive sun gear would turn counterclockwise, but is held from turning by the coast clutch mechanical diode. The input shaft turns the same speed as the center shaft and transmits torque through it.

In 2nd, 4th and 6th gears, the overdrive clutch is applied, the mechanical diode overruns and holds the overdrive sun gear fixed to the case. This causes the overdrive planet to walk around the sun gear and over-drive the overdrive ring gear.

Mechanical diodes are model dependent. The higher RPM of the gasoline engines require a mechanical diode unique from that used on higher torque diesel engines.

Fig 1: Overdrive One-Way Clutch Mechanical Diode

Courtesy of FORD MOTOR CO.

Item	Part Number	Description
1	-	Overdrive one-way clutch (OWC) inner race (overrunning)
2	-	Overdrive one-way outer race (stationary)
3	-	Counterclockwise rotation
4	-	Julian date