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 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.