Abstract: The pans of a scraper-chain conveyor have a plough guide at one side. The pans are connected together at said one side with the aid of coupling pieces engaged in pockets in the side walls of the pans. Each coupling piece is pivotably fitted to a plate-like securing element which serves as a handle to enable the coupling piece to be inserted into or removed from the pockets. The securing element can be swung down into further pockets formed in the plough guide to lock the coupling piece in place.

Abstract: A hydraulic control system for a mine roof support unit has a control valve assembly for controlling the hydraulic appliances of the unit, and an actuator for actuating the control valve assembly. The actuator has a valve block provided with a plurality of pairs of spool valves. The spool valves of each pair are detachably fixed in a pair of generally parallel bores formed in the valve block. Each pair of spool valves is provided with a respective rocker arm for actuating purposes. Each of the rocker arms is mounted on a respective cover plate, which covers the mouths of the corresponding pair of bores, and which is detachably secured to the valve block.