Improvements relating to chocks, nogs, or props of noninflammable materials for colliery underground roof control

摘要

597,444. Mine roof supports. MOORHOUSE, E. A. Feb. 26, 1946, No. 5896. Drawings to Specification. [Class 20(ii)] A reinforced concrete chock for building pack-walls in colliery underground workings is formed with a longitudinal hole into which the shaft of a removable handle is fitted to facilitate handling.