Clutches are used in automatic transmissions to control gear train members.
In a Borg Warner 35 transmission there are three clutches.
A one-way or overrunning clutch located between the planet carrier and the center support, a multi-plate clutch located inside the drum attached to the input shaft, the front clutch, and a multi-plate clutch located inside the drum attached to the secondary sun gear, the rear clutch.
The one-way clutch is a sprag type which locks the planet carrier to the center support whenever the carrier tends to turn in the opposite direction to the transmission input shaft.
The inner race of the clutch is provided by an extension on the center support while the outer race is formed in the planet carrier.
The equally spaced sprags are held together by a spring-loaded cage which maintains them in the correct position and attitude before fitting.
Correct fitment is essential otherwise the planet carrier will freewheel when it should be locked up and no drive will be transmitted in "D" range 1st gear.
When the sprags are fitted in place the cage moves them together so that each carries an equal share of the load when the planet carrier is locked.
Turning the planet carrier in the opposite direction to the input shaft pivots the sprags towards the larger radius and wedges them between the two races.
