Abstract: A fluid pump for a linear actuator causes a rod in the actuator to extend or retract by controlling fluid flow to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes check valves that control fluid flow between a driven pump element and each portion of the fluid chamber and a shuttle movable in response to fluid pressure along a shuttle axis extending through the valves. At least one valve includes a valve member movable between a closed position and an open position defining a fluid flow path between the driven pump element and fluid chamber and means for limiting movement of the shuttle towards the valve such that the shuttle may, depending on the position of the limiting means, move the valve member to an intermediate position between the closed and open positions.

Abstract: A fluid pump for a linear actuator causes a rod in the actuator to extend or retract by controlling fluid flow to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes check valves that control fluid flow between a driven pump element and each portion of the fluid chamber and a shuttle movable in response to fluid pressure along a shuttle axis extending through the valves. At least one valve includes a valve member movable between a closed position and an open position defining a fluid flow path between the driven pump element and fluid chamber and means for limiting movement of the shuttle towards the valve such that the shuttle may, depending on the position of the limiting means, move the valve member to an intermediate position between the closed and open positions.

Abstract: A fluid pump for a linear actuator is provided. The pump causes a rod in the actuator to extend or retract by controlling the flow of fluid to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes a valve structure that enables the pump to redistribute fluid obtained from one portion of the fluid chamber on one side of the piston to the other portion of the fluid chamber on the other side of the piston without first returning the fluid to a fluid reservoir thereby increasing the efficiency of the pump.

Abstract: A fluid pump for a linear actuator is provided. The pump causes a rod in the actuator to extend or retract by controlling the flow of fluid to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes a valve structure that enables the pump to redistribute fluid obtained from one portion of the fluid chamber on one side of the piston to the other portion of the fluid chamber on the other side of the piston without first returning the fluid to a fluid reservoir thereby increasing the efficiency of the pump.

Abstract: A fluid pump for a linear actuator is provided. The pump causes a rod in the actuator to extend or retract by controlling the flow of fluid to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes a valve structure that enables the pump to redistribute fluid obtained from one portion of the fluid chamber on one side of the piston to the other portion of the fluid chamber on the other side of the piston without first returning the fluid to a fluid reservoir thereby increasing the efficiency of the pump.

Abstract: A fluid pump for a linear actuator is provided. The pump causes a rod in the actuator to extend or retract by controlling the flow of fluid to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes a valve structure that enables the pump to redistribute fluid obtained from one portion of the fluid chamber on one side of the piston to the other portion of the fluid chamber on the other side of the piston without first returning the fluid to a fluid reservoir thereby increasing the efficiency of the pump.