Automatic connecting valve for hydraulic systems

In combination with at least two pumps (3 and 4) and a fluid operated device (2), a valve assembly (1) connected to said fluid operated device and having a valve piston (18), a valve body (10) and a spring (17) biasing the valve piston to a neutral position, fluid pressure actuating means (31-22) connected to one (3) of the pumps for displacement of the valve piston from said neutral position to a changeover position against the bias of said spring, and flow restriction means (37) interconnecting said one of the pumps to the fluid actuated means including a flow orifice member (36) and passage restricting means (39-44) engageable therewith for varying flow area as functions of pressure and valve movement, said passage restricting means including a support pin (38), a sleeve (39) fixed to the pin having stepped diameter portions (24, 54), a disc (44) axially movable on the pin and spring means (45) supported in the sleeve in engagement with the disc for bias thereof away from the orifice member.

In combination with at least two pumps (3 and 4) and a fluid operated device (2), a valve assembly (1) connected to said fluid operated device and having a valve piston (18), a valve body (10) and a spring (17) biasing the valve piston to a neutral position, fluid pressure actuating means (31-22) connected to one (3) of the pumps for displacement of the valve piston from said neutral position to a changeover position against the bias of said spring, flow restriction means (37) interconnecting said one of the pumps to the fluid actuated means for accelerating movement of the valve piston between the neutral and changeover positions at which the valve piston is stabilized under pressure of the pumps, and a pressure resistance valve section (7) connected to said one of the pumps downstream of the flow restriction means for regulating the pressure of said one of the pumps in the neutral position of the valve piston.

In a combination including a pair of pumps (3 and 4) supplying pressurized fluid to a fluid operated device (2), a valve assembly (1) for controlling changeover between said pumps, and a valve actuator having a pair of pressure chambers (31 and 22) and restricted passage means connecting said chambers to one (3) of the pumps for developing a differential valve actuating pressure, the improvement residing in flow control means (37) for varying said valve actuating pressure, comprising means (36 and 44) responsive to the pressure of said one of the pumps and displacement of the valve assembly for varying the flow area of said restricted passage means.