GB500259A - Improvements in or relating to pit props - Google Patents

Abstract

500,259. Pit -props. CERLACH, K. Aug. 3, 1937, No. 21434. Convention date, Aug. 3, 1936. [Class 20 (ii)] A pit-prop or mine arch of the kind comprising an upper tapered member adapted to move relatively to a lower member and be locked thereto by movable wedge members, has a locking element coacting with inclined surfaces on the wedges whereby they are moved parallel to the length of the prop or arch. The wedges 4 are secured to links 5 which are pivoted to a support 3, and the locking element 7 coacts with inclined faces provided on each wedge, whereby the horizontal forces transmitted to the wedges are resisted by vertical forces on the locking element. The locking element may be in the nature of a tractive body to draw the wedges together, if the resistance to relative movement of the prop members 1, 2 results in the wedges tending to move apart. Double wedge elements may be interposed between the main wedges and the upper prop. member 1, and these wedges as well as the main wedges and the locking member may be in the form of rings surrounding the prop. The inclined surfaces provided on the wedges for interaction with the locking element and this element also may be inclined in a second direction so that it is forced towards the upper prop member when the prop is under load, as shown in Fig. 5, with or without the interposition of packing 11 between the locking element and the prop or interposed double wedge 9. As shown in Fig. 11, a single wedge 4 together with a locking element 7 is used with an outer wedge 13. Specification 475, 560 is referred to.