| 摘要 |
Actuating equipment for a gate valve or penstock uses both compressed air and hydraulic oil to obtain the advantages of both. A control valve directs air to a hydraulic reservoir so as to drive oil at the air pressure into one chamber of a double acting cylinder and piston connected to the gate. When the gate is not being moved it is locked in position by an air operated valve preventing oil flow. A normally energized solenoid operated control valve opens when electrical power fails so as to direct stored air from a reservoir to move the gate to a fail-safe position. Air pipelines may provide communication over some distance from the control valves to the gate valve or penstock. This can avoid running electric cable through a hazardous environment, while to give fail-safe operation in the event of damage to the pipelines, these are placed within a larger bore line supplying air to hold closed an air operated valve, which, in the event of loss of pressure in this line opens so that stored air moves the gate to its fail-safe position and also operates a valve preventing movement away from that position. Means are provided to apply an enhanced force to the gate for part of its travel.
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