Mine roof supports for step- by- step movement

EFIXED CONSTRUCTIONS E21Mining E21DSHAFTS TUNNELS GALLERIES LARGE UNDERGROUND CHAMBERS

E21D23/00Mine roof supports for step- by- step movement

E21D23/0004along the working face E21D23/0008comprising a pair of joined struts E21D23/0013Frame type supports E21D23/0017Pile type supports E21D23/0021comprising two walking elements E21D23/0026comprising three walking elements E21D23/003consisting of a rigid pile E21D23/0034comprising a goaf shield articulated to a base member E21D23/0039and supported by a strut or by a row of struts parallel to the working face E21D23/0043and supported by two or more rows of struts parallel to the working face E21D23/0047without essential shifting devices E21D23/0052with advancing shifting devices connected therewith E21D23/0056with individual advancing shifting devices E21D23/006provided with essential hydraulic devices E21D23/0065driven, or automatically E21D23/0069without essential advancing shifting devices E21D23/0073with advancing shifting devices connected therewith E21D23/0078with individual shifting devices E21D23/0082specially adapted for vertical or steep gradient seams E21D23/0086in galleries E21D23/0091at the junction with the working face E21D23/0095Temporary supports at the driving front E21D23/03having protective means E21D23/04Structural features of the supporting construction E21D23/0409Aligning or guiding means for the supports or for the constitutive parts of the supports E21D23/0418Positioning devices and stabilizing means for the props E21D23/0427Shield operating devices; Hinges therefor E21D23/0436Means for inclining the base member of the support E21D23/0445Extensions of the base member supporting the conveyor E21D23/0454Trailing plates; Coal face or goaf side sprags E21D23/0463Hanging or shifting means for tubes, electric feeding cables or the like E21D23/0472Supports specially adapted for people walking or transporting material E21D23/0481Supports specially adapted for use in combination with the placing of filling-up materials E21D23/049Connecting devices between the head or foot of a prop and the cap or base of the roof support E21D23/06Special mine caps or special tops of pit-props for permitting step-by-step movement E21D23/063Retractable cantilever extensions therefor E21D23/066Pivoted cantilever extensions therefor E21D23/08Advancing mechanisms E21D23/081forming parts of the roof supports E21D23/082acting solely on the elements of the supports E21D23/083acting on a firm abutment adapted thereto E21D23/085acting on a conveyor or a guide for the mining machine E21D23/086Details of fixing devices therefor E21D23/087acting directly on the walls of the seam E21D23/088by means of wheels, rollers, caterpillars, belts or worm screws E21D23/10with advancing devices separate from the supporting construction E21D23/12Control E21D23/14Effecting automatic sequential movement of supports E21D23/142Measuring the advance of support units with respect to external points of reference E21D23/144Measuring the advance of support units with respect to internal points of reference E21D23/146Transmission of signals and commands by cable E21D23/148Wireless transmission of signals or commands E21D23/16Hydraulic or pneumatic features E21D23/18of advancing mechanisms E21D23/20for sequential movement E21D23/22incorporated in mine caps E21D23/24the advancing mechanisms being separate from the supporting construction E21D23/26Hydraulic or pneumatic control