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LuK Gmbh & Co.

Dry Double Clutch for Transmissions

The LuK Dry Double Clutch is intended to displace wet clutches in double-clutch transmissions, which are relatively new themselves, but being adopted rapidly.

Because it uses electromechanical instead of hydraulic activation, a dry clutch lets a double clutch transmission shift faster, and with less drive train power loss, while the assembly weighs less than a wet clutch, in both cases, owing to the absence of clutch fluid.

Both performance and fuel economy improve because an engine is loaded near its peak torque performance a higher percentage of the time. This effect is most noticeable during start-stop driving, as in urban areas, where there is also an efficiency gain.

Because of fuel economy savings of up to 10%, it is planned that the dry double clutch will enter Asian markets soon. The key technical breakthroughs in dry double clutch transmissions are the friction materials and the architecture for dissiplating and radiating heat from the transmission, instead of cooling by means of a fluid bath.

The dry double clutch is a major step toward lighter-weight, more responsive electrical control of a vehicle than is possible with hydraulic systems. Dry clutches may be very useful in future drive train designs, as with torque transfer in hybrid drive systems.

The LuK dry double clutch first appeared in the Volkswagen 7-speed DSG transmission, with many more adoptions to follow.