Fluid power transmission and control system for fluid motors for driving the front wheels of a vehicle

Claim 1

A vehicle having an engine drivingly connected by mechanical power transmission means to its rear wheels and a fluid power transmission and control system operable to selectively drive fluid motors directly drivingly connected to respective front steering wheels, said system comprising a main hydraulic pump operatively connectible to the mechanical transmission such that its fluid output is dirctly proportional to the ground speed of the driven rear wheels of the vehicle so that when said main pump fluid output is supplied to said fluid motors the fluid motors are driven at a speed having a predetermined proportional relationship with the ground speed of the rear wheels, a closed fluid circuit from said main pump connectible through first valve means to said fluid motors, an auxiliary hydraulic pump operatively connected to the engine, a fluid path from said auxiliary pump connectible through second valve means with the fluid motors to enable the auxiliary pump to pressurise the fluid motors to put the fluid motors in their free-wheeling states, and control means to enable the selective actuation of said first and second valve means so as to connect, and disconnect, the transmission and control system to drive, and from driving, the fluid motors, said disconnection being simultaneously with said pressurizing of the fluid motors by the auxiliary pump.