| 摘要 |
A fuel system comprises a spill valve 38 operable to relieve the fuel pressure differential across at least one positive displacement pump 16, 18 , a shut-off valve 32 operable to control the supply of fuel to an engine 84 , and a two stage servo-valve 62 operable to control the operation of the shut-off valve 32 , the spill valve 38 having a control chamber 40 the fluid pressure within which is controlled so as to be held at an intermediate level during engine shut-down.
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