In a system for the supply of fluid under pressure to machinery of an underground mine working, lengths of fixed conduit are secured to parts of the conveyor assembly, prior to the assembly of said parts at the underground mine working. When the conveyor assembly has been assembled, the length of fixed conduits are interconnected, either by straight lengths of flexible conduit, or by branched lengths of flexible conduit, where take off for fluid under pressure is required for the machinery, for example a roof support unit.