Clutch controlled by engine speed and transmission selector

Claim 1

In a motor vehicle of the type having a change speed gear, a friction clutch, and a source of fluid under pressure different from atmospheric pressure, an automatic clutch operating system comprising: a cylinder having a piston therein operably connected to the clutch said piston moveable in a clutch engaging and clutch disengaging direction; means providing a fluid flow connection between said cylinder and the source; a first valve disposed in said connection means and positionable to connect said cylinder either to said source or to a first conduit leading to the atmosphere; a second valve disposed in said first conduit for controlling the rate of flow therethrough; a second conduit connected to said first conduit and leading to atmosphere; adjustable flow restricting means in said second conduit; a third valve disposed in said second conduit and movable between an open position for allowing the passage of fluid through said second conduit and a closed position for preventing said passage; a first electromagnet operatively associated with said first valve and adapted, when energized, to move said first valve to a position in which said cylinder is connected to said source so as to cause disengagement of said clutch; a second electromagnet operatively associated with said third valve and adapted, when energized, to move said third valve to said closed position thereof; first electRical circuit means for operating said first electromagnet comprising a first switch for controlling energization and deenergization of said first electromagnet; second electrical circuit means for operating said second electromagnet comprising a second switch for controlling energization and deenergization of said second electromagnet; means movable in unison with said piston and positioned so as to engage said second switch to thereby open said second circuit means and deenergize said second electromagnet as said piston moves in said clutch disengaging direction; a motor speed responsive control element means movable between two positions one of which corresponds to a predetermined minimum motor speed and the other to a maximum motor speed; first actuator means for said first switch; second actuator means for said second valve, said first and second actuator means being associated with said control element means so as to open said first switch and thereby deenergize said first electromagnet, and so as to open said second valve to an extent corresponding to the speed of said motor above said minimum speed, upon movement of said control element means away from said one position thereof.