GB620177A - Improvements in adjustable props - Google Patents

Abstract

620,177. Props for tunnels &c. HALLETT, R. D., LOWE, N. J. BOWYER-, and LANDAUER, W. Nov. 28, 1946, No. 35266. [Class 20(ii)] An adjustable prop comprises a tube having fine adjustment relatively to a lower bearing plate and carrying telescopically a second tube, the two tubes having each a set of equally spaced diametrically opposed holes, but of different pitch, so that adjustment of the height of the prop can be effected by pressing a pin through different aligning holes of the two tubes. The fine adjustment may be effected by inclined planes or wedges e.g. by rotation of the lower part of the prop relatively to the lower load bearing plate, which may have cam surfaces. The lower tube 2, Fig. 1 receives telescopically the upper tube 1 which is provided with a top plate 5 either welded to the tube or to a plug 6 mounted in the tube by a spring ring 8 which engage recesses both in the plug and in the tube. Holes 3, 4 in the two tubes, of slightly different pitch provide for adjustment of height by suitable choice of the aligned holes through which a pin is to be passed to lock the prop. The lower tube is located within a housing 10, Fig. 2, welded to a base plate 9, the lower tube having diametrically opposed projections 13 which run on cam faces 12 on a liner within the housing 10, when the tube is rotated relatively to the housing. A stop 14 on the projections 13 engages the inturned flange 15 on the housing to prevent movement of the projections past the highest points of the cam faces. Slidable wedges, (not shown) are located between the head plate and the load to be supported.