| 摘要 |
A butterfly valve or a similar quarter-turn valve is provided with a locking mechanism which permits the disc assembly to be rotated from the open position to the closed position, but prevents the disc assembly from being rotated back to the open position. The locking mechanism includes a cam carried on a rotatable stem supporting the valve disc assembly. The cam has a camming surface including a detent notch situated at a location corresponding to the open position of the disc assembly. A plunger, which is spring loaded into engagement with the camming surface, is urged into the detent notch when the disc assembly is rotated from the open to the closed position and prevents the disc assembly from being rotated back to the open position.
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