GB718457A - Improvements in lagging irons for mine roofs and the like - Google Patents

Abstract

718,457. Lagging irons for mine roofs. URINES ET ACIERIES LEONARD-GIOT SOC.- ANON. April 21, 1952 [April 23, 1951], No. 9984/52. Class 20 (2) A lagging iron a, Figs. 1, 2 with end projection 2 is pivotally supported cantilever fashion from the forked end 5 of a similar preceding lagging iron b by means of a pivot pin 8 and wedge 9 and in order to permit limited lateral angular deflection of the iron a relative to the iron b, whilst maintaining full contact between the abutment surfaces, the abutment surface 10 on the iron a and the corresponding face 11 of the wedge 9 are flat and parallel to the upper surface 13 of the iron a whilst the opposed face of the wedge 9 engaging hook projections 7 on the iron b is of arcuate form, the pivot receiving hole 3 at its ends or alternatively the pin 8 at its middle portion being made slightly oval to permit free play. The abutment surface 10 is the upper face of a slot 4 in the end projection 2. The lagging irons may be made reversible by providing two pairs of projections 7 symmetrically arranged and a centrally arranged slot 4 with top and bottom abutment faces 10. In this case also the two projections 7 in each fork arm may be combined to form a closed elongated slot 7 , Fig. 11 (not shown). In another embodiment the slot 4 and wedge 9, Fig. 6, are of arcuate form and to prevent its loss the pin 8 is provided with opposed longitudinal slots which are engaged by set screws 17 in lugs 19 on one of the forks 5. The lagging irons which may be cast metal, are of boxsection formed with apertures 16, 20, Fig. 4, and reinforced with transverse walls 21 which may also be apertured. The lower portion of each lagging iron has spaced projections 22 along its length adapted to localize its seat on the prop head.