GB706861A - Improvements in or relating to roof supporting structures for mines - Google Patents

Abstract

706,861. Mine roof supports. BATHGATE, G. M. July 15, 1952 [July 27, 1951], No. 17810/51. Class 20 (2) A splayed H-section pit prop is formed at its upper end with a part 12 of reduced crosssection straddled at its base by a wedge 15 supporting a vertically adjustable channel shaped head 17 slidable on the part 12, the head 17 carrying on its base a wedge 25 straddling the part 12 and supporting a roofing bar support block 21 slidable on the part 12 and vertically adjustable relative to the head 17 so that a roof bar 22 may be inserted or removed without removing the prop from its supporting position. The roof bar 22 rests on friction material 26 carried by a block 21. A bolt 27 is secured to and extends between opposite sides of the head 17 and passes through slots 28 in the block 21 and through a slot 29 in the reduced part 12, thus limiting upward movements of both the head 17 and block 21. The head 17 may be widened to accommodate a W-cross-section roofing bar and the block may be modified to support either such a bar or to accommodate the lower flanges of an H-section roofing bar within recesses formed in the block. Fig. 6 (not shown) shows a girder 22 supported by props in a roof support system in which the girder 22 is slid forwards on the props as the coal face advances. Specification 428,055 is referred to in the Provisional Specification.