GB767398A - Roof bars for use in mines - Google Patents

Abstract

767,398. Mine roof supports. RITCHIE, C. June 28, 1954 [April 7, 1953], No. 9334/53. Class 20(2) In a system of roof support for mines, two or more roof bars 9, 9A, Fig. 2, placed closely together side by side, are supported by U- shaped heads 1 at the top of pit props, Fig. 1 (not shown), and are forced upwards against the mine roof by wedges 6, 6A driven in the direction F between the bottoms of the bars and inclined planes 7 in the heads 1. The heads 1 are provided with top parts 5 and bridge pieces 4 which contact the mine roof. The roof bars are recessed at 10, 10A to receive the bridge pieces 4. In operation, the part 9 for example, may be released whilst the bar 9A remains in a roof supporting position, and the bar 9 is then advanced until recesses 10 are again directly positioned beneath the bridge pieces 4, the wedges 6 then being driven in to force the' bar 9 against the roof. When the bar 9 is in the tightened position the bar 9A may be similarly released and advanced. The roof bars may have wedges or inclined planes constructed on or welded on at intervals along the length. The roof bars may have recesses on both their upper and lower surfaces so that they are reversible.