IMPROVEMENTS IN OR RELATING TO MINE ROOF SUPPORT BARS

摘要

1292518 Mine roof support bars GEWERKSCHAFT EISENHUTTE WESTFALIA 9 April 1970 [9 April 1969] 16893/70 Heading E1E A mine roof support bar is provided with a U-shaped spring member 2, the longer arm 3 of which rests in sliding engagement on the upper face 1' of the bar while the shorter arm is fixed to a bolt and bracket 6, 7. The shorter arm may itself be U-shaped (Fig. 2) or may extend around a bending abutment bolt (9, Fig. 3). A number of springs may be provided (Fig. 4). An L-shaped member is shown in Fig. 5, the foot (12') of the L being connected to a stack of leaf springs 11 which are prestressed by means of an adjusting screw 18.