Mine support roofbar for face junctions - midway bar linked by springs to off-centrally propped main side bar sections

摘要

Multiple mine support roofbar for use at face/road junctions underground includes an unpropped midway bar between two propped roofbar sections. The props (12, 13) carrying the main sections (10, 11) are each placed offset towards the free unconnected end of their respective roofbar sections whilst springs are secured at one end to the main section ends where these adjoin the interposed midway bar (20). The other ends of the springs are clamped under tension against the midway bar so that when the roofbar system is taken off load the midway bar remains level or slightly bowed towards the roof. The springs should be of the stack type whose free outward ends bear against the height-adjustable surfaces of the midway bar as specified. It is possible to clamp the springs in shoes which are rigidly connected to the main bar sections (10, 11) by the bolts forming the hinge pins between these and the midway bar.