Abstract: The invention provides a mine conveyor, for use in hazardous atmospheres, comprising an endless conveying belt; an electric motor; and a torque transmission arrangement located between the electric motor and the endless conveying belt, the torque transmission arrangement incorporating a modulated wet clutch and a torque converter, with a drive drivable by transmission gearing and adapted to make driving relationship with the endless conveying belt; and a control system for controlling the torque transmission arrangement, the system comprising an electro-hydraulic control circuit incorporaitng an intrinsically safe (as herein defined) unit to monitor and control the conveyor, at least one microprocessor incorporated in the intrinsically safe unit, the microprocessor incorporating a memory whereby a ramp starting mode, a running mode, and a stop mode required for the conveyor are preprogrammable into the microprocessor, and at least one transducer included in the electro-hydraulic control circuit to monitor at

Abstract: A bi-directional torque transmission unit (1) comprises an input shaft (2) connectable to a prime mover and provided with an input drive gear wheel (3), first and second driven shafts (4, 4A) each having a driven gear (5, 5A) constantly in mesh with the input drive gear wheel (3), so that they are rotatable in the same direction, a hydraulically actuated and modulated clutch (7, 7A) interconnecting each driven shaft (4) with an intermediate, output shaft (6, 6A) and a final, output shaft (11) connectable to a load, and both the first and the second output shafts (6, 6A) having an output gear (12, 12A) whereby selective or simultaneous engagement of one or other of the modulated clutches (7, 7A) transmits torque to the final output shaft (11).

Abstract: A variable speed conveyor drive system, which is programmable to suit various operating conditions; comprises a master drive unit (7) having a drive motor (16), at least one slave drive unit (8-10, 14, 15) having a drive motor (16), a monitor and control unit (23), a control loop (24, 26, 27, 37, 58) from the master drive unit (7) to the monitor and control unit (23), a multiplexer (25) with a master outlet (26) and a slave outlet (27) for each slave drive unit (8-10, 14, 15), the master multiplexer outlet (27) being connected to the master drive unit (7) to form a part of the control loop (24, 26, 27, 37, 58), whereby all motors (16) share the load at a pre-programmed level at any speed of operation, and each slave multiplexer outlet (27) having an individually adjustable and programmable time delay operable both before start-up and during running of the conveyor (1).

Abstract: A control valve arrangement includes at least one first supply and exhaust valve, and a second supply and exhaust valve. The first and second valves are arranged in series and are manually operated with a single hand. The first valve is manually displaced in one direction, and the second valve is displaced in the opposite direction.

Abstract: A self-advancing, hydraulically powered mine roof support comprises a base means, a double-acting hydraulic advancing ram extending in the intended direction of advance of the support in use, the cylinder of the advancing ram being located towards the forward end of the support and the piston rod of the advancing ram being located towards the rearward end of the support, a lifting ram mounted on the support at or towards the forward end thereof and being operable on the periphery of the cylinder to lift the forward end with respect to the cylinder, the end of the cylinder remote from the piston rod being connectable to a pan of an armoured conveyor, and the advancing ram being connected to the support by an inclined link means pivotally attached to the base means and to the piston rod.

Abstract: A control system for a hydraulically powered self advancing mine roof support, which system ensures that a hydraulically extensible chock leg of the support is set to a predetermined pressure, irrespective of the length of time that a main inlet valve is held open comprises an auxiliary valve interposed between a main valve and a chock leg(s) in a fluid supply line extending from a high pressure line to the support, a bypass line connected to the high pressure line in advance of the main valve and extending to the auxiliary valve, the auxiliary valve being so constructed as to open upon sensing a predetermined pressure and to close upon sensing a higher predetermined pressure.