The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 16, 1988
Filed:
Jun. 30, 1986
John W Curnow, Utica, MI (US);
Vickers, Incorporated, Troy, MI (US);
Abstract
A hydraulic control system comprising a hydraulic actuator having opposed openings adapted to alternately function as inlets and outlets for moving the element of the actuator in opposite directions and a pump system with load sensing control for supplying fluid to said actuator. A meter-in valve is provided to which the fluid from the pump is supplied and a manual or electrohydraulic controller alternately supplies fluid at pilot pressure to the meter-in valve for controlling the flow therefrom to the actuator to control direction and displacement of movement of the meter-in valve and the direction and velocity of the actuator. A pair of lines extends from the meter-in valve to the respective openings of the actuator. A meter-out valve is associated with each line to the actuator for controlling flow out of the actuator. Each meter-out valve is operated by the pilot pressure from the controller. Provision is made for sensing the maximum load pressure in one of a series of valve systems controlling a plurality of actuators and applying the higher pressure to the load sensing pump system. In addition, combined hydrostat and load drop check valves are provided to provide the dual function of maintaining a predetermined pressure drop across the meter-in valve, independent of actual pressure, which will result in constant flow as well as provide the load drop check valve function of opening during flow from the meter-in valve and closing when the meter-in valve is in neutral for venting of the meter-in valve.