Pit prop cap support screen - has cantilevered bar hinged via guide rods to pistons and cylinders which are on each side of support plate

摘要

For preventing large pieces of coal from falling from the face onto the conveyor, in thick seams in mines, the support prop has a cap with a support screen. A piston-and-cylinder assembly (22) is mounted on each side of the screen's support plate (24), with one end hinged to this plate, and the other end hinged to a guiderod, via a parallel rotary axis. The two guide-rods are hinged to a cantilevered support bar (10) on the cap (2), also via parallel rotary axes (17, 19). There is a device for advancing and withdrawing this bar - pref. a double-action pressure block. This means that piston-and-cylinder assemblies with relatively short thrust can be used, saving cost and space.