Load responsive control system

A load responsive fluid control system comprising a fluid pump having an output flow control and an outlet, a fluid motor subjected to load pressure, exhaust means, and a direction control valve interposed between said outlet of said pump, said fluid motor and said exhaust means, said direction control valve having first valve means for selectively interconnecting said fluid motor with said pump and said exhaust means and for providing variable orifice means between said outlet of said pump and said fluid motor, load pressure sensing port means in said direction control valve selectively communicable with said fluid motor and with duct means connected to said output flow control of said pump, second valve means responsive to pressure in said load pressure sensing port means in said direction control valve having control means and fluid throttling means operable to throttle fluid flow from said fluid pump to said fluid motor to maintain a constant pressure differential at a preselected constant level across said control means of said second valve means and to maintain a constant pressure differential across said variable orifice means, third valve means having means operable through said fluid throttling means of said second valve means to vary level of said constant pressure differential across said variable orifice means while said pressure differential across said control means of said second valve means remains constant at said constant predetermined level, and fourth valve means operable through said output flow control of said pump to control the pressure differential between pressure in said pump outlet and pressure in said load pressure sensing port means.