Mechanical function, overview

Fig 1: Active On Demand Coupling Mechanical Function Overview

Courtesy of VOLVO CARS OF NORTH AMERICA.

1. Pressure plate
2. Rollers for the annular piston
3. Rollers for the operating piston
4. Annular piston
5. Operating piston
6. Input shaft
7. Cam disc
8. Housing for the outer plates
9. Outer plates
10. Inner plates
11. Springs
12. Output shaft.

The gearbox transfers engine torque to the propeller shaft. The input shaft is separate from the output shaft. The multi-plate clutch in the coupling must be engaged to transfer torque to the rear axle. The inner and outer wet multi-plate clutch are the transfer point between the input and output shafts.

The sinusoidal cam disc rotates at the same speed as the propeller shaft. The annular piston rollers act on the cam disc to press the annular piston in and out. This creates an oil pressure which affects the operating piston, which in term engages the multi-plate clutch unit.