This invention relates to a control system for a pressure operated clutch adapted to be engaged under speed synchronized conditions to smoothly transmit torque to a change speed gear unit.
Control systems of the foregoing type are known and used for most variable friction clutches, including dry and wet clutches in association with various vehicle gear transmissions. Often, a fluid torque converter having a by-pass clutch associated therewith is disposed between the engine and the speed synchronized clutch as disclosed for example in German Pat. No. 33 05 999. The use of such control systems enables manual gear shift control by inexperienced drivers under most difficult conditions to a qualitively acceptable degree in so far as road traction is concerned. However, such control systems do not as yet enable gear shift control by an inexperienced driver with satifactory quality in so far as torque reversing gear shifts are concerned.
It is therefore an object of the present invention to provide a control system for a pressure operated clutch associated with a reduction gear unit, wherein speed synchronization between clutch elements is achieved for good quality drive ratio change operation under driver control, including those drive ratio changes which involve a reversal of torque.