Improvements in or relating to coal face shoring structures

摘要

756,069. Mine roof supports. BECORITGRUBENAUSBAU GES. Dec. 8, 1953, No. 34089/53. Class 20(2). Mine roof supporting girders are connected by a unit 3 comprising a pivot bolt 5 formed in one unit with a wedge 6 which is driven between the ends of two girders to hold one of them against the roof while props are placed beneath it. The bolt and wedge may be releasably connected. The girders engage by a tongue 10 and a fork 9 and the wedge is driven in an aperture 7a in the tongue 10 and engages the end of the fork. In Fig. 4 the wedge 6 engages downwardly extending parts of the girders beneath the bolt 5.