Constant speed differential fluid clutch

Claim 1

Torque transmission apparatus comprising, in combination: a housing; first and second shaft means rotatably supported in said housing; slip clutch means for providing a continually slipping connection between said first and second shaft means, said slip clutch means including a chamber for fluid and having a continuously variable torque transmitting capacity Controlled by the pressure of the fluid within said chamber; pump means having a driving member operatively connected to said first shaft means and a reaction member operatively connected to said second shaft means for providing a fluid pressure varying with the speed differential between said shaft means; a source of fluid under pressure separate from said pump means, valve means comprising a bore and a fluid exhaust conduit in said housing, said bore having one end in communication with said varying fluid pressure from said pump means and further having first, second and third axially spaced valve ports, said first valve port being in communication with said separate source of fluid pressure, said between valve port being in communication with said chamber and said third valve port being in communication with said fluid exahust conduit, said value means further comprising an axially reciprocable spool in said bore, said spool having two axially spaced lands and a reduced diameter center portion, one of said lands blocking said first valve port with said reduced diameter center portion providing communication between said second and third valve ports when said spool moves toward said open end of said bore, the other of said lands blocking said third valve port with said reduced diameter center portion providing communication between said first and second valve ports when said spool moves toward the other end of said bore, said one land blocking said third valve port and said other land blocking said first valve port when the spool is intermediate said open and said other end of said bore; said valve means further comprising a spring in said bore between said spool and said other end of said bore, said spring biasing said spool toward said open end of said bore.