Ford Kuga

 Service Manual

Rear Drive Axle/Differential » Rear Drive Axle and Differential (System Operation and Component Description)
Pressure control - 4th generation Haldex clutch

Full torque is available at any time on the 4th generation Haldex clutch because the pressure is not dependent on the difference in the speeds of rotation. This is used for instance to activate the Haldex clutch for better traction when moving off.

On the 4th generation Haldex clutch, the preload function which applied 80 Nm to the plates in the 3rd generation is no longer required.

On request from the control unit and at engine speeds above 400 rpm, the electric feed pump runs and maintains the storage pressure at about 30 bar.

A pressure reducing valve acts as a control valve, allowing the all-wheel drive control unit to control the pressure with much greater precision. The all-wheel drive control unit monitors the position and function of the control valve. The control valve distributes the pressure, depending on the requirements, across its three outlet openings (storage pressure, working pressure, return).

From the storage pressure (30 bar) and depending on the requirements, the control valve regulates a working pressure of 0 - 17 bar, which is applied to the ring piston. At 17 bar working pressure, the maximum torque of 1000 Nm is transferred to the rear wheels. The all-wheel drive control unit ensures the best possible performance under all driving conditions, for all road conditions and independent of the speed.

General Information

Driving situations

Haldex clutch

Design of the 3rd generation Haldex clutch

Design of the multi-plate clutch

All-wheel drive control unit

Electric feed pump

Pressure control - 3rd generation Haldex clutch

Base pressure

Increased base pressure (preload)

Pressure build-up

Design of the 4th generation Haldex clutch

Pressure control - 4th generation Haldex clutch