Patent ID: 8091355
Filing Date: 2012-01-10
Classification: E02F,F15B

Abstract:
1. A hydraulic system for providing fluid under pressure to an actuator having an extendable and retractable piston rod and first and second ports, comprising: a hydraulic fluid pressure source configured to draw hydraulic fluid from a reservoir and in communication with the actuator to move the piston rod in a first direction and in a second direction that opposes the first direction, and wherein a load on the actuator acts to move the piston rod in the second opposite direction in concert with the hydraulic fluid pressure source; a control valve for directing hydraulic fluid under pressure from the hydraulic fluid pressure source to the actuator to move the piston rod; and a flow compensated valve carrying flow between the control valve and the first port of the actuator and having at least two flow states, a first flow state of the flow compensated valve providing flow from the hydraulic fluid pressure source to move the piston rod in the first direction and, when the hydraulic fluid pressure source and the load on the actuator are acting upon the piston rod to move it in the second direction, providing substantially unrestricted flow from the first port of the actuator below a selected flow rate, and a second flow state of the flow compensated valve for substantially restricting flow through the flow compensated valve to a selected flow rate, when the flow rate through the flow compensated valve exceeds the selected flow rate, detected as a pressure drop across the flow compensated valve.