LuK GmbH & Co. KG · Germany

Modern cars are characterised by constantly increasing engine torque. With an unchanged envelope, the clamping force on the clutch to transmit the engine torque inevitably increases. At the same time, the actuation force which the driver must exert on the pedal to declutch also increases.

Depending on the vehicle model, the driver must apply pedal effort of approx. 13 – 18 kg with a torque of around 350 Nm, when he activates the clutch. However, with pedal travel of up to 15 cm the maximum maintainable actuation forces are around 12 kg.

LuK Clutch Servo Assistance in detail
The LuK servo unit is positioned in the hydraulic release system between the master and slave cylinder, i.e. between the pedal and clutch. The system comprises an electromotive pump as well as a control valve which sets a particular pressure ratio between the master and slave cylinder. The support is in proportion to the actuation force and does not require any sensors or electronics.

Depending on the vehicle model for which the LuK CSA is used, an oscillating compressive strength is defined from which the pump is supported. Tolerances, changes in propagation and frictional hysteresis are also partially compensated due to the support which is proportionate to pressure.

The system is primarily self-sufficient and designed as an add-on solution, i.e. there are few interfaces and the base unit can be flexibly used for various applications.