Abstract: A series of filter backflushing valves are connected to a pressurized air storage tank and are sequentially opened at selectively variable time intervals by a piston and stepping cam structure reciprocably disposed within a cyclic control device intermittently pressure actuated by a backflushing pressure control valve which controls pressurized air flow from the tank to the control device, to actuate the same, through an actuating conduit by automatically opening when the tank pressure reaches a desired backflushing pressure level established by the valve setting. The lapse time between sequential backflushing valve openings may be varied independently of the selectively variable backflushing pressure by adjustment of the flow rate of pressurized supply air into the tank through a main supply conduit.

Abstract: A control system for operating positive displacement hydraulic motors to minimize pressure peaks and stresses associated therewith upon starting the motor at full fluid flow includes a self-closing pilot operated valve which, upon initiation of fluid flow to the motor bypasses a majority of the flow to a return line circuit and progressively closes to force pressure fluid to accelerate the motor to a preselected operating speed. The self-closing valve includes a spool type closure member which is pilot actuated through a timing orifice to commence closing upon initiation of fluid flow therethrough from the pump discharge or supply line. The closure member is spring biased in the open position and automatically resets itself to the open position upon shutdown of the motor operating valve.

Abstract: A cyclic or periodic event timing system for use in conjunction with a pressure fluid control circuit includes a cylinder and piston type actuator comprising a differential area piston which is exposed to fluid pressure from a flow conduit on opposite sides of a flow restricting orifice in the conduit or a branch portion thereof. The actuator piston includes a rod portion which is extended in one direction in response to an unbalanced pressure force on the piston. On the extension stroke, the actuator opens a valve to effect flow in the conduit resulting in a reduction in pressure which is sensed in the cylinder chamber exposed to the larger piston fluid area. The actuator piston then returns to an initial retracted position in response to an unbalanced pressure force.