| 摘要 |
<p>An interlock mechanism for three rotatable members 26, 27 and 28 mounted in a body 18 with their axes parallel and having a chordal flat 33, 34 and 35 respectively includes a ring 48 which surrounds with clearance those parts of the members having the flats. When one member is turned from its base position to engage its cylindrical surface with the ring, the ring is slid laterally to engage with the flats of the other two members, which thereafter cannot be turned until the first member is reset to its base position. The interlock mechanism is particularly suitable for use with fluid flow control valves, where one of the members may be arranged to connect the drive to a valve operating component when turned from its base position. Two keys may be provided, one for effecting turning movement of each of the two other members, the keys being releasable only when the associated rotatable member has been turned from its base position. By restraining movement of the two keyed rotatable members other than when the valve is set to one or the other extreme setting, respectively, the valve may be operated only when both keys are present, and possession of a key guarantees the valve is set to an extreme setting.</p> |
