Improvements in or relating to pit props and chock pieces for use in coal mines and the like

摘要

396,454. Pit props and supports. BRITTON, W., 2, Brompton Terrace, Whickham, MAGEE, S. S., Coley Hill, Westerhope, and WOOD & CO., Ltd., H., Sun Buildings, Collingwood Street, all in Newcastle-on-Tyne. Feb. 10, 1932, No. 3979. [Class 20 (ii).] Pit props or chocks of the type in which a cap is adjusted on the prop by means of a wedge, have a loose plate fitting on the cap so that it can be moved by hammer blows to cause the initial release of the cap. The cap 2 is formed with triangular-shaped side portions and a top flat portion to which is loosely fitted a plate portion 4 with projecting ends, to which blows may be applied. The cap is adjusted by means of a transverse wedge 5 fitting between it and a sloping portion at the end of the prop 1, and a transverse bolt 3 in a slot prevents separation of the cap. In a modification, the end portions 2 may be provided with inward projections to contact a bolt to prevent separation of the cap, and in a further modification, a separate wedge-head may be fitted to the top of the main prop for contact by the wedge. As applied to a chock, Fig. 7, the retaining bolt 14 slides in transverse slots in the bearing iron 10 and in coverplates 11 a, a wedge chock-block 11 being also used for contacting with the wedge.