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

The engine torque is transferred to the propeller shaft via the gearbox. The input shaft is separate to the output shaft. The multi-plate clutch pack in the coupling must be loaded for torque to be transferred to the rear axle. The inner and outer wet plates are the points at which drive is transferred between the input and output shafts.

The sinusoidal cam disc rotates at the same speed as the propeller shaft. The rollers for the annular piston act on the peaks and troughs of the cam disc. This presses the annular piston in and out, generating an oil pressure which acts on the operating piston, causing it to engage the multi-plate clutch pack.