GB839211A - Mine roof bars - Google Patents

Abstract

839,211. Mine roof supports. PROGRES CHARBONNIER PROCHER SOC. COOPERATIVE. May 23, 1957 [July 14, 1956], No. 16365/57. Class 20(2) A mine roof bar as a fork end comprising limbs 5 in which are bores 6 for a pivot pin and slots 8 for a hoisting wedge, which latter contain a movable block 11. Bars are coupled end to end by inserting the tongue end of one bar between the limbs 5 of another and inserting a pivot pin through the bores 6 and aligned bore in the tongue. Whichever side of the bar is uppermost the block 11 drops to the lower ends of its slots 8 so that insertion of a 'hoisting wedge in the slots 8 causes the one bar to pivot around the pin and be clamped against the roof. Alternatively, the block may slide in a slot in the tongue (Fig. 1, not shown) or pivot in an open slot at the end of the tongue (Fig. 5, not shown). The working faces of the block may be machined and the sides be correspondingly shaped. The block may be held in place by a spring loaded ball or bolt or by magnetization. The slot may be rectangular or curved about a radius centering on the pivot.