Friction transmission

Friction transmission device comprising:

• at least one rotatably mounted shaft;
• means defining a presser cylinder and piston assembly composed of a cylinder member and a piston member mounted in said cylinder member, both of said members being mounted to rotate with one said shaft, one of said members defining a friction disc arranged to press against a cooperating element for transmission of motion between such element and said disc, the other of said members being fixed to the shaft on which said members are mounted, and both of said members defining a presser cylinder chamber for receiving hydraulic fluid at a pressure for urging said disc against the element with a force dependent on the friction force required to transmit motion between such element and said disc;
• and
• means defining a torque sensor mounted on one said shaft and hydraulically connected to said presser cylinder chamber, said sensor defining a fluid flow control valve composed of two valve parts movable relative to one another to an extent dependent on the torque imposed on the shaft on which said sensor is mounted for exclusively controlling the pressure in said pressure cylinder chamber in dependence on the torque imposed on the shaft on which said sensor is mounted;
• wherein said valve parts are constructed for delivering a predetermined supplemental volume of hydraulic pressure fluid to said presser cylinder chamber upon a predetermined relative movement between said valve parts in a direction to increase the pressure in said presser cylinder chamber.