System Overview

System overview

Power transmission




1. Bevel gear: Transmits torque from transmission to propeller shaft. Always rotates at the same rate as the front wheel pair.
2. Propeller shaft: Transmits torque from front axle (bevel gear) to rear axle. Always rotates at the same rate as the front wheel pair.
3. Active On demand Coupling (AOC): At four-wheel drive, the AOC transmits torque from the propeller shaft to the rear wheel pair. Rotates at four-wheel drive.
4. Differential gear: Transmits the force to the rear wheel pairs. Rotates at the same rate as the front wheels at four-wheel drive.

Active On demand Coupling (AOC)




Active On demand Coupling (AOC) and its Differential electronic module (DEM) (4/82), has as its most important function to control the function for four-wheel drive, that is, power distribution between front and rear axle.
The system consists of an integrated clutch with a mechanical, a hydraulic, and an electronic part.
The clutch unit is located on the rear axle, between the final drive and the propeller shaft. The mechanical part is driven by the propeller shaft. The hydraulic part is driven by an electric pump.
Active On demand Coupling (AOC) generation 4 enables the following characteristics:
- Continuous control of four wheel drive, with electronic control of torque transfer.
- Rapid reactions
- No opposing forces when maneuvering or parking.
- Improved stability.
- Reduction of oversteering/understeering.

Clutch unit and control module




1. Accumulator
2. Oil filter
3. Pressure reducing valve
4. Inner and outer wet clutch plates
5. Inner connection hub with splines for output shaft. The hub has a sinusoidal cam curve
6. Input shaft
7. Electrical feed pump.
8. Differential electronic module (DEM)
9. Non-return valve
10. Annular piston
The Differential Electronic Module (DEM) is fitted on the clutch unit housing.
The Differential Electronic Module (DEM) communicates with other control modules via CAN:
The control module has integrated diagnostics for its own components and functions.

Signals
The table below summarizes input and output signals to and from the Differential Electronic Module (DEM). The illustration below displays the same information with the Volvo component designations.