| 摘要 |
1,216,953. Advancing mine roof support assemblies. GEWERKSCHAFT EISENHUTTE WESTFALIA. 16 April, 1969 [12 Oct., 1968], No. 19472/69. Heading E1P. In an advancing mine roof support assembly comprising a central frame II adapted to be advanced in parallel relative to two interconnected outer frames I, III by aligned and interconnected means 6, 7, 8, 8' the central frame is pivotally connected as at 9, 10 to the advancing jack means and positioned relative thereto by auxiliary jacks 11, 12. |
