Advancing mine roof support structure for mine working faces

摘要

874,435. Advancing mine roof supports. HAARMANN, A. Dec. 2, 1957 [Dec. 12, 1956], No. 37525/57. Class 20(2) An advancing mine roof support comprises a row of T-shaped frames 10, 11 connected by advancing devices 20, the free ends of the central members 11 of the frames pointing alternately to the coal face 18 and the goaf 19. The central members 11 may be joined to the cross members 10 by flanges 12 to which hydraulic cylinders 20 are hinged. Pit props are carried in sockets 13-15.