Differential clutch released by hydraulic brake application

Claim 1

A vehicle having hydraulic brakes and a differential drive means connecting two final drive shafts, a hydraulic system including a source of pressurized fluid, a hydraulically actuated clutch locking said differential drive means for synchronously rotating said final drive shafts, a hydraulic control valve means including manual means controlling the flow of pressurized fluid from said source of pressurized fluid to said hydraulically actuated clutch and a hydraulic operating means biasing said valve to interrupting communication between said source of pressurized fluid and said hydraulically actuated clutch, a hydraulic brake circuit having brakes for braking each of said final drive shafts, a hydraulic relay valve connected through said control valve in said hydraulic system connected between said source of pressurized fluid said hydraulically actuated clutch and said hydraulic operating means of said control valve including actuating means hydraulically in communication with said hydraulic brake circuit for operating said relay valve means, a spring normally biasing said relay valve in one direction to a first position for directing flow of pressurized fluid from said source of pressurized fluid to said hydraulically actuated clutch, said relay valve comprising a hydraulic actuator in communication with one of said hydraulic brakes, a second hydraulic actuator in communication with the other of said Hydraulic brakes, said hydraulic actuators both moving said relay valve in a second direction opposite to said first direction to a second position against the force of said spring means for directing the flow of pressurized flow from said source of pressurized fluid to said hydraulic operating means on said control valve means to close said control valve means and deenergize said clutch on said differential drive means to thereby deenergize said hydraulically actuated clutch in response to actuation of one or both of said hydraulic brakes.