Abstract: 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.

Abstract: In a valve-actuating mechanism of the kind which is manually manipulated for actuating the valve-actuating member, the combination of a helical cam surface formed on a friction ring, a follower solid with the handwheel shaft and two confronting cylindrical surfaces carrying clutching dogs, a spring being inserted therebetween. Frictional forces are exploited for causing the axial displacement of the handwheel overcoming the spring bias.