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. 18, 1992
Filed:
Aug. 30, 1989
Kurt R Lonnemo, Bloomfield Hills, 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 an element of the actuator in opposite directions, a pump for supplying fluid to the actuator. A meter-in valve individual to each opening is provided to which fluid from the pump is supplied and a pair of lines extending from the respective meter-in valves to the respective openings of the actuator. A controller alternately supplies pressure to the respective meter-in valves for controlling the direction of movement of the load. A second pair of lines extends from the first pair of lines to tank and a variable pressure relief valve is positioned in each line of the second pair of lines. When the controller is moved to actuate one of the meter-in valves for supplying fluid to one of the openings of the actuator, the controller also actuates the variable relief valve associated with the line of the first pair of lines extending from the other of the openings of actuator to control the flow out of the other opening. The controller thus simultaneously controls the fluid flow and the pressure to the actuator and the fluid pressure from the actuator, thereby simultaneously controlling the driving and braking functions of the system.