Roof contacting structure for mine roof support - is extendable bar pivoted to piston and unit and extension bar via fixed or adjustable length links

摘要

The roof contacting structure of a mine roof support has a main roof bar (1) pivoted (4) to an extension bar (3). A piston and cylinder unit (5) pivots the extension bar about the main bar to bring it into contact with the roof aligned with the main bar, or into a stowed position beneath a main bar. Pivoted links (8) are connected between the main and auxiliary bars and to the piston and cylinder unit at a pivot (7). The links (8, 9) may be of fixed length or of variable length, a piston and cylinder unit (19) being used as one of the links.