Hydraulic control arrangement for a roof support unit of a miner

Details Hydraulic control arrangement for a roof support unit of a miner Hydraulic control arrangement for a roof support unit of a miner

1980-12-19

1984-04-03

Corbin, David H.

Hydraulic and earth engineering

Earth treatment or control

Shoring, bracing, or cave-in prevention

405299, 405302, 91170MP, 91520, E21D 1514, E21D 2300, E21D 2316, F15B 1120

Patent

active

044405227

ABSTRACT:
A roof support unit for a longwall mineral mining installation has a roof shield supported above a floor sill. A first hydraulic ram is provided for advancing the roof support unit. The roof shield is provided with a forward extension which is advanceable by means of a second hydraulic advance ram. A hydraulic control arrangement, which includes the two hydraulic advance rams is provided for controlling the advance of the roof shield extension in dependence upon the working stroke of the first hydraulic advance ram. The control arrangement is such that the amount of hydraulic fluid supplied to one of the pressure chambers of the second hydraulic advance ram is dependent upon the amount of hydraulic fluid expelled from one of the pressure chambers of the first hydraulic advance ram during the working stroke of the first hydraulic advance ram.

REFERENCES:
patent: 2475298 (1949-07-01), Sloane
patent: 3436922 (1969-04-01), Irresberger et al.
patent: 3530490 (1970-09-01), Ward et al.
patent: 3795177 (1974-03-01), Cryder et al.
patent: 3990594 (1976-11-01), Olson et al.

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