Mine roof supports
US4797023A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 20, 1987 |
| Grant date | Jan 10, 1989 |
| Priority date | — |
| Expiry date | May 20, 2007 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21D23/0039
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A mine roof support has a roof engaging canopy 23, a floor engaging base 12, and a hydraulic jack 24 acting between the canopy and the base for urging the canopy and the base apart. The hydraulic jack 24 is provided with at least two different locations, movement of the jack means 24 from one location to another location bringing about an alteration in the distance between the canopy and the base. The invention makes it possible to provide a hydraulic jack having a first working position in which the hydraulic jack is arranged in the optimum position to support a mine roof, and a second stowing position for transportation purposes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.