Abstract: A mine roof support has a main roof bar which is pivotably connected to an auxiliary forwardly-extendible bar. At least one piston and cylinder unit serves to swing the auxiliary bar about the main bar to bring the auxiliary bar into a roof-contacting position aligned with the main bar or into a stowed position beneath the main bar or into some intermediate position. One or more pivotable guide levers connect the auxiliary bar to the piston and cylinder unit. A guide member is also connected to the unit and slidably locates in longitudinal guideways formed in ribs or the like at the underside of the main roof bar.

Abstract: A mineral mining installation comprises a mine roof support assembly and apparatus for drilling bores. The roof support assembly comprises a plurality of roof support units positioned side-by-side, and the drilling apparatus comprises a drilling device which is movably guided on a track associated with the roof support assembly. Each of the roof support units has at least one roof bar. The track is arranged on the underneath sides of the roof bars of the roof support units. The drilling device is pivotally mounted on a trolley which is movably guided on the track.

Abstract: A mine roof support unit is constituted by two detachably connected parts. Each of the parts has a floor girder which supports a roof bar by means of a hydraulic prop. The roof support unit is intended for use at the lower end of an inclined longwall working which meets its access gallery at an angle other than 90.degree.. The detachability of the two parts enables one of these parts to be removed from the working as its face is advanced. The removed part can then be transported to the other end of the working. Each of the parts is provided with means for detachably connecting an advance mechanism.