| 摘要 |
1,205,960. Valves. A. G. WILD & CO., Ltd. 24 Oct., 1968 [27 Oct., 1967], No. 48958/67. Heading F2V. A valve block controlling a mine roof support having a pair of props and an advancing ram is provided with two pairs of valve members, each arranged as in Fig. 4 for controlling a respective end of the ram, and a further two pairs of valve members each arranged as in Fig. 5 for controlling a respective one of the props. In Fig. 4, rotation of lever 23 cams a loose thrust plate 24 and the spring loading of inlet valve 3 and exhaust valve 4 is such that the plate 24 initially seats the valve 4 and then pivots about the end of the latter to unseat valve 3. A flat 28 on the lever 23 enables the latter to remain in its actuated position. In Fig. 5, both the inlet and exhaust valves are biased to closed positions. Clockwise rotation of lever 30 unseats valve 3 but the lever cannot reach a dead-centre position. Anti-clockwise rotation of lever 30 is transmitted by arm 35 to unseat valve 4. Co-operating flats 36, 37 allow the lever to remain set in this position. The exhaust valves controlling the ram may selectively discharge into the same or a different line to the exhaust valves controlling the props. Some of the inlet valves may have a separate supply line. Check valves 39, 40 allow connection of pressure gauges. In Fig. 1 (not shown), inlet and exhaust valves (3, 4) are biased to closed and open positions respectively, and are actuated by a rotary face cam (16). The exhaust valve seat is yieldable against a spring (14). |
