Improvements in, and relating to, collapsible struts, and other prop-like devices, such as pit-props

摘要

317,146. Bramah, J. H. May 16, 1928. Mine props are formed of two hollow or solid members a, b with inclined abutting faces c retained in contact by a two-part rotatable sleeve e each part of which is provided with corresponding inclined abutting faces so that, when the whole of the abutting surfaces register, the two parts of the prop may be moved laterally with respect to each other. The sleeve is disposed between collars d fixed to the members. In order to prevent the two members becoming entirely separate, an external chain attached to each is used, or alternatively a pivoted link h is used having a pin and slot connection k with one part, and with bearing surfaces n to contact with the internal sides of the members in the collapsed position. The lower portion of this link rests on a spring plate which is depressed during collapse and helps to restore the prop to working position again. When the members are hollow, side fillings o of wood are disposed on each side of the link and these fillings are also provided with inclined contacting faces at the joint. Removable packing may be used in the lower end of the prop to enable its length to be varied.