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Fig 1: Active On Demand Coupling Mechanical Function Overview

Courtesy of VOLVO CARS OF NORTH AMERICA.

Pressure plate
Rollers for annular pistons
Rollers for the operating piston
Annular piston
Operating piston
Input shaft
Cam disc
Housing for the outer clutch driven plates
Outer clutch driven plates
Inner clutch driven plates
Springs
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.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Mechanical Function, Overview

Use the Manual With the Right Hardware

When to See a Mechanic