Shield support for coal mines - roofbar adjusts over forcibly guided roof wards curved path at shield tip

摘要

Shield support for mines consists of a floor bar (6), hinged waste shield (8) and roofbar (11) at the leading end of the shield which can pivot vertically relative to the shield. The roofbar travels a curved path towards the roof (2) as imposed by guides (13) in relation to the free or leading end of the main shield, and the roofbar can be located in any adjusted intermediate position along this path. Preferably the centre of curvature of this path remains level or above the horizontal plane through the rear axis (9) of the shield (8) in fully collapsed condition, the curve of the path such as exclude any braking effect between roofbar (11) and leading shield end. Guidance over this path derives from a groove open to the roof in the shield tip, or a groove in the roofbar open to the floor travelled by a guide on the bar or shield end.