Mine roof supports

Details Mine roof supports Mine roof supports

1982-12-20

1983-12-27

Corbin, David H.

Hydraulic and earth engineering

Earth treatment or control

Shoring, bracing, or cave-in prevention

405302, E21D 1544

Patent

active

044228074

ABSTRACT:
A mine roof support has hydraulic props mounted between a floor sill and a roof bar which can be raised and lowered by extension and retraction of the props. A goaf shield is pivotably connected to the rear of the roof bar and is linked via levers to the floor sill. A hydraulic piston and cylinder unit is connected between the roof bar and the goaf shield. Apparatus serves to prevent damage to the support components, and especially to the unit which could be extended beyond its full stroke when the props are retracted to bring the goaf shield and the roof bar more or less into alignment. The protective apparatus is composed of a compact valve device operated by a member, such as a cam, to block the props from hydraulic pressure when the goaf shield and the roof bar assume a pre-determined angular disposition. Both the valve device and its operating member are disposed in a protected position within chambers formed inside the roof bar and the goaf shield adjacent the pivot connection therebetween.

REFERENCES:
patent: 3400634 (1968-09-01), Wirtz
patent: 3478522 (1969-11-01), Rieschel
patent: 3898845 (1975-08-01), Plevak et al.
patent: 4222686 (1980-09-01), Bell et al.

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