| 摘要 |
<p>In a control device such as a valve actuator, the improvement comprises means for indicating the number of revolutions undergone by the valve actuator. The rotatable valve actuator drives a plurality of spaced-apart shafts which are geared to each other in suitable driving ratios with each shaft carrying an indicator to indicate the angular position of that shaft. The combination of indicators provides an indication of the number of revolutions by the valve actuator. Means can also be provided to operate one or more sets of electrical contacts when a predetermined digital indication is reached.</p> |
