Hydraulically-operated devices
US4422808A · kind A · utility
0Cited by
11References
3Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 7, 1982 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Jul 7, 2002 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21D23/20
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An assembly of mine roof supports each of which has a control member and a hydraulically-operated member, e.g. a cantilever. The cantilevers operate one after the other in a predetermined sequence in response to actuation of one of the control members. Each cantilever is associated with a pressure-operated control valve and two serially-connected control valves which normally prevent operation of a cantilever in response to actuation of a control member unless the next-before cantilever in the series has completed its operation and the control member which caused that next-before cantilever to operate has been actuated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.