Mine road-head supports - have brackets on each forepole to carry wall spragging segments and crossbar on adjoining forepole brackets

摘要

Arch segments are forepoled at the crown to accept the legs. Walls sprags are mounted on the forepole bars to hold the walls before the legs are finally fitted. The sprags are designed (42) as channel segments hinged to brackets run along the forepole bars ahead of the crown segment position and can be located at spacing on these bars, as well as swung out and be locked in this position. Crossbars (49) are fitted to adjoining brackets on adjacent forepoles (7, 8) to prevent the bars (7, 8) from swivelling. The longitudinal axes of the sprags (42) and/or crossbars (49) adapt to the wall leg segments.