| 摘要 |
A rotary screw compressor having one or more stages (10, 20) is provided with a lift valve (14, 24) on each stage for unloading the compressor at starting up and rest periods. Each lift valve (14, 24) is affected by a spring (15, 25) towards open position and can be closed by actuating means (17, 27). According to the invention the actuating means (17, 27) are automatically controlled by air conduit means (32) establishing air communication between the discharge channel (23) of the compressor and each valve actuating means (17, 27).
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