Patent · US Expired

Hydraulic control systems for mining apparatus

US4391181A · kind A · utility

4Cited by

5References

4Claims

0Family size

Assignee

Gewerkschaft Eisenhutte Westfalia GmbH · DE

Inventors

Walter Weirich · Dortmund, DE
Michael Dettmers · Kamen, DE
Kunibert Becker · Werl, DE
Harry Rosenberg · Philadelphia, US

Key dates

Filing date	Nov 17, 1980
Grant date	Jul 5, 1983
Priority date	—
Expiry date	Nov 17, 2000

Classification

Technology area (CPC E)Fixed Constructions
CPC primaryE21D23/26
WIPO fieldCivil engineering
WIPO sectorOther fields

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.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.