Vehicle/engine operational parameter responsive clutch control

A control system for a hydraulic automatic clutch of a vehicle having an engine with a throttle which opens in degrees, comprising:

• a hydraulic clutch having an output shaft;
• an engine revolution speed sensor means for generating an engine revolution fluid pressure signal indicative of the revolution speed of the engine;
• a vehicle speed sensor means for generating a vehicle speed indicative signal indicative of the vehicle speed;
• a starting valve means having a start fluid pressure regulating state and a complete engagement fluid pressure regulating state, said starting valve means being coupled with said engine revolution speed sensor means for generating a start fluid pressure in response to said engine revolution fluid pressure signal when said starting valve means is in said start fluid pressure regulating state, said starting valve means increasing fluid pressure from said start fluid pressure to generate a complete engagement fluid pressure when said starting valve means is in said complete engagement fluid pressure regulating state, said start fluid pressure and said complete engagement fluid pressure being supplied to said hydraulic clutch;
• a complete engagement control means coupled with said starting valve means for rendering said starting valve means operable in said complete engagement fluid pressure regulating state when said complete engagement control means is put into a predetermined state;
• control means including means for generating a predetermined vehicle speed indicative signal indicative of a predetermined vehicle speed, said control means being responsive to said vehicle speed indicative signal for putting said complete engagement control means into said predetermined state when said vehicle speed indicative signal increases beyond said predetermined vehicle speed indicative signal.