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 transmission coupling 1 for location between an electric motor 2 and a gearbox 3, comprises a rigid housing 4, an input shaft 5 rotatably supported within the housing 4, an output shaft 6 also rotatably supported within the housing 4 and connectable to the input shaft 5 by operation of a hydraulically actuated, multi-plate clutch 11, the output shaft 6 also carrying some elements of a multi-plate brake 22, other elements being carried by the housing 4, the brake 22 being spring loaded into operative position and hydraulically displaceable into a non-operative position, a constant pressure pump 31 to provide hydraulic pressure fluid to effect operation of the clutch 11 and brake 22, in accordance with the fluid volume demanded by clutch and brake operation, the pump volume output automatically being adjusted in response to such demand, and at least one control valve 35 to control the flow of the hydraulic fluid to the working circuit 39.

Abstract: A reciprocable piston hydraulic pump is provided with a piston periphery sealing means 24 comprising, at the pressure side, a seal 25 of flexible material and adapted to surround the piston periphery, a ring 27 separating the seal 25 from a moulded pressure seal, with a reservoir 28 defined between the seal 25 and the pressure seal, and spring means 29 operable on the seal 25 to urge the latter towards the pressure seal 26.

Abstract: A hydraulically actuable piston and cylinder unit comprising a hollow piston rod, slidably housing, at least partially, an elongate extension piece having a circular outer periphery, means to connect mechanically, the extension piece to the piston rod at the outer end of the latter remote from the piston head, at least one fluid passageway communicating between the annulus side of the piston head and the hollow interior of the piston rod, and a fluid seal carried by the extension piece and sealing against the internal periphery of the hollow piston rod, the arrangement being such that the seal always lies between the passageway and the outer end of the hollow piston rod.

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: This invention relates to a face sprag for mining equipment, to a mine roof beam incorporating such a sprag and to a mine roof support provided with such a beam. The face sprag comprises a sprag plate, a piston and cylinder unit pivotally attached at one end about a first pivot axis to the sprag plate and at the other end about a second pivot axis to a portion of a support member, a link means pivotally attached at one end about a third pivot axis to the piston and cylinder unit and at the other end about a fourth pivot axis to the support member at a location spaced from the second pivot axis, all the pivot axes being parallel, and activation of the piston and cylinder unit urging the sprag plate, in use, into an operative position in engagement with the mineral face.

Abstract: A mine roof support comprises a plurality of hydraulically extensible chock legs 5,6, articulated at upper ends thereof to one or more roof beams 3 and at lower ends thereof to one or more base members 1, a shield 9 pivotally connected to a rearward part of the base member 1 and also pivotally connected to a rearward part of the roof beam 3, with permanently pressurized rams 12 both located between a pair of laterally spaced chock legs 6 and one located to each side of the center line 19 of the support, the rams being mutually inclined with respect to the center line 19 and reacting via the shield 9 on the roof beam 3, and a pair of tie bars 11 located one at or towards each side of the support and both connected between the roof beam 3 and the shield 9.

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.

Abstract: A mining installation comprises an armoured conveyor made up of a plurality of pans articulated together end-to-end, a plurality of hydraulically powered, self-advancing mine roof supports located side by side along the goaf side of the conveyor, each roof support being connected to a pan by one or more double-acting advancing rams, and each having a base means incorporating a pair of spaced, elongate base members seating on a mine fooor, each support further having a forward end intended to be located, in use, adjacent the goaf side of the conveyor and a rearward end intended to be remote from the conveyor, a rail located between the base members and attached at a forward end thereof to a pan of the conveyor, and a lifting jack carried by the base members at or near the front end thereof and operable on the rail to lift the front ends of the base members from the mine floor and in this condition be advanced towards the conveyor by operation of the one or more double-acting advancing rams.

Abstract: A mine roof support comprises a plurality of hydraulically extensible chock legs articulated at upper ends thereof to one or more roof beams and at lower ends thereof to one or more base members, a shield pivotally connected to a rearward part of the base member(s) and also pivotally connected to a rearward part of the roof beam(s) with a permanently loaded force applying means reacting via the shield on the roof beam(s), in such a manner that the force applying means resists displacement of the roof beam(s) and, upon a sufficient fall in pressure in the chock legs, restores any displaced chock legs to a predetermined position.

Abstract: A mine roof support comprises at least one hydraulically extensible chock leg connected at its upper end in articulated manner to a roof beam of the support, and connected at its lower end in articulated manner to a base member of the support, a pair of links each having bearing surfaces adapted either to embrace a common chock leg by bearing on opposite sides thereof or to bear on adjacent sides of a pair of spaced apart chock legs, one end of each link being pivotally attached to the base member at a pivot point located to one side of a diametral plane passing through the longitudinal axis of the chock leg on which the link bears, the other end of the link being located to the other side of that plane and being acted upon by a restoring ram adapted to displace the or each link about it or their respective pivot points, to restore the or each leg to its predetermined position upon release of the support from the roof, and also to resist tendency for the or each leg to become displaced from the predetermined

Abstract: A self-advancing, hydraulically powered, mine roof support comprises at least one advancing piston and cylinder unit located in or adjacent a base means of the support and attached at or towards the front of the roof support to a lifting ram operable along an axis normal to the general plane of the base means.

Abstract: A mine roof support comprises a plurality of hydraulically extensible chock legs attached at their upper ends to one or more elongate roof bars by means of a projection on each chock leg passing through an aperture in the underside of the roof bar(s) to be located in articulated manner in any one of a plurality of positions along the roof bar(s) and within the roof bar(s) by abutment means.

Abstract: A mine roof support comprises at least one pair of hydraulically extensible chock legs connected at upper ends in articulated manner between one or more roof beams of the support and connected at lower end in articulated manner to one or more base members of the support, a rigid yoke located at a position spaced from the base member(s) between and connecting either the pair of chock legs, the yoke containing between the chock legs a projecting pin secured in a bearing attached to the yoke, or one of the pairs of chock legs, the yoke containing two projecting pins each pin being secured in a bearing attached to the yoke, and the or each pin having a lateral base contained at one side between abutment surfaces secured to the base member(s) and at the other to one end of a load applying means, the other end of the load applying means being supported from the base member(s).