Abstract: A cutter bit assembly for a mining or tunnelling machine has a cutter shank detachably fitted into a socket of a holder. To secure the shank in position a piston is displaced to cause pressure fluid to flow into a working chamber and act on a piston at one end of a rod-like securing element. The element is forced against a surface of the shank to urge the shank about a pivot and this in turn thrusts rear support surfaces of the cutter and the holder together. To release the cutter the pressure fluid is relieved and spring force displaces the securing element away from the shank. In this released condition, the cutter can be swivelled about the pivot and withdrawn from the socket.

Abstract: A floor cutter for a plough has a component provided with cutting edges fixed by welding to a main body locating in a holder. The components are connected together with step-like surfaces chamfered at the external faces of the components to faciliate the welding. Superimposed support surfaces extend more or less normally to other surfaces and permit adjustment of the position of the components during welding to vary the set cutting depth.

Abstract: A mineral mining installation employs a scraper-chain conveyor constructed from individual pans joined end-to-end and a plough having a drive plate running beneath the conveyor and on a skid bed formed as a sub-frame structure on the floor of the working. The drive plate is connected via guide means to the haulage run of a chain in a lower guide passage at the side of the conveyor opposite to the plough. An upper guide passage accommodates the return run of the chain. The passages are defined by a guide structure fitted to the side walls of the pans and includes detachable covers which can be removed for access purposes. At least some of the covers are linked with the sub-frame structure with the aid of tongue-and-groove connections.

Abstract: Apparatus for controlling the cutting horizon of a mineral winning plough comprises means for pivoting the guide along which the plough moves. The guide is fixed to the face side of the conveyor, and said means acts on the goaf side of the conveyor. Said means comprises a plurality of control devices, each of which has an upstanding plate fixed to the goaf side of the conveyor, an abutment member pivotally connected to the base of the upstanding plate, and an actuator arranged between the abutment member and the upstanding plate. The actuators are effective to pivot the conveyor relative to the abutment members. Each actuator comprises a hydraulic ram and a toggle linkage which magnifies the working stroke of the ram.