| 摘要 |
<p>1,187,208. Valves. W. E. & F. DOBSON Ltd. 9 May, 1967 [25 May, 1966], No. 23301/66. Heading F2V. [Also in Division E1] A valve controlling the operation of longwall mining apparatus (see Division F1) comprises supply and exhaust valves 41, 45 which are urged to the position shown by pilot fluid acting on respective pistons 46, 47 to allow pressure fluid to flow to an advancing jack via inlet 30, passage 35 and outlet 31. The valves are retained in position after the pilot signal ceases by the pressure acting thereon in chambers 34, 32a. To reset the valves, pressure fluid is admitted to port 61 and acts on reset pistons 54, 57 to move the latter rightwards to seat valve 41 and unseat valve 45. Port 31 is now connected to exhaust port 33. The pilot fluid can be controlled by solenoid-operated valves.</p> |
