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:
Jul. 05, 1983
Filed:
Nov. 17, 1980
Walter Weirich, Dortmund, DE;
Michael Dettmers, Kamen, DE;
Kunibert Becker, Werl, DE;
Harry Rosenberg, Ludinghausen, DE;
Gewerkschaft Eisenhutte Westfalia, Lunen, DE;
Abstract
A hydraulic control system, particularly for controlling the operation of roof support props of a mine working, employs control devices operated manually to feed pressure fluid to the working chambers of the props to effect extension or retraction thereof. A two-state valve device is operated when the props are extended to ensure that the correct setting pressure is established. This valve device has a control piston which is actuated to cause the device to establish independent connection between the main fluid pressure line and the associated working chambers of the props charged with fluid by the initial operation of the control devices. The connection established by the valve device is maintained even if the control devices break connection between the chambers and the pressure line. When the correct setting pressure is reached, a further control piston of the valve device is actuated to break the connection established by the valve device ready for the next operative cycle.