4WD coupling
The rear end of the propeller shaft is equipped with a drive flange attached to the Hardy coupling with 3 bolts and nuts. The Hardy coupling, in turn, is bolted to a drive flange on the all-wheel drive clutch. The all-wheel drive clutch and the rear final-drive unit are directly connected.
The all-wheel drive clutch serves as the actuator that continuously controls the amount of torque being transmitted to the rear axle. The four-wheel drive clutch serves the same function as the clutch used with a manual transmission by providing positive engagement for transmitting power: between the propeller shaft and the rear final-drive unit's input shaft.
The all-wheel drive clutch is controlled by the DSC control unit. The link between the four-wheel drive clutch and the DSC is provided by a 2-pin plug connection.
A twisted-strand wire with shielding is used for the connection to the all-wheel drive clutch. This configuration is necessary for electromagnetic compatibility (EMC) because the all-wheel drive clutch is controlled with a clocked (pulse-width modulated) signal.
| Item | Explanation |
|---|---|
| 1 | 4WD coupling |
| 2 | two-pin plug connection |
| 3 | Final drive |
| 4 | Ventilation connection |
The all-wheel drive clutch housing is air-tight and sealed against liquids. To provide the necessary pressure compensation when substantial changes in temperature occur, a vent line is provided; this leads to a raised installation location where no sealing against water is required (luggage compartment).