Abstract: A flow limiting, surge damping directional control valve (11) utilizes flow regulating and surge damping means (30) for limiting the rate of flow of an operating fluid in a fluid flow path so as to absorb surge irregularities during the operation of the valve (11). The flow regulating and surge damping means (30) is carried by a movable valve member (25) adapted to control the flow and direction of flow of the operating fluid of the fluid flow path. This arrangement includes a flow regulating piston (35) having metering ports (37) for regulating the rate of flow of the operating fluid across the piston (35) and means (29) for slidably mounting the flow regulating piston on the movable valve member (25) so that the flow regulating piston (35) is positioned adjacent a selected port of the valve (11) during the operation thereof.

Abstract: A hydraulic isolation valve (10) will not open if leaks are present in the associated utility subsystem (15). The continuity of the hydraulic fluid circuit actuates the valve (10) to the open position by an energized solenoid operated pilot valve (21) sending a small flow through a fuse (23) and one-way restrictor (24) to the utility function (15). If no leaks are present, the utility function (15) begins to actuate sending return flow through a two-way restrictor (31) and moving a continuity actuation piston (28) to push the shut off spool (16) to the open position so that full flow is admitted to actuate the utility function (15). If the continuity of the hydraulic circuit is broken by leaks, the return flow does not reach the continuity actuation piston and the shut off spool (16) remains in the shut off position, the fuse (23) closing to block further flow and then resetting by spring action when the solenoid operated pilot valve (21) is deenergized so that actuation may be attempted again, if desired.