| 摘要 |
1, 098, 628. Mine roof supports. COAL INDUSTRY (PATENTS) Ltd. March 16, 1965 [March 20, 1964], No. 11932/64. Addition to 967,163. Heading F1P. A mine roof support has a hydraulic roof support member 2 and a horizontal advancing ram 1, a control valve 6 actuated by pressure acting on the ram 1 from a supply 3 to lower the member 2 by allowing fluid to escape from it to a return line 4, and a second control valve 8 actuated at a predetermined positional setting of the ram, e.g. by an abutment 18 on the ram engaging the valve, to over-ride the valve 6 to raise the member 2. The operation is started by opening a valve 5, and fluid-pressure then opens the valve 6, and advances the ram 1. When the valve 8 is opened, the pressure is transmitted along a line 9 to close the valve 6, and through a non-return valve 11 to raise the member 2. The valve 8 and abutment 18 may be replaced by an opening in the ram cylinder, connected to the lines 9 and 12 and uncovered by the piston near the end of its stroke. The valve 5 may be opened by fluid-pressure, e.g. from the line 9 of an adjacent unit, the units then operating sequentially Fig. 2 (not shown). In another embodiment Fig. 3 (not shown) the line 9 leads through a two-way fluid-pressure operated valve to the valves 5 of an adjacent unit on each side and the units are operable sequentially either from left or right or right to left. Reference has been directed by the Comptroller to Specification 967,164. |
