Overtravel of a Rotary Vane Actuator

it has the ability to go 5% past the stop. You then adjust the limit within this range to get the precise fit and it stops at the limit you set. There is usually a limit at the other end as well, but there may not be, you might have a spring return to an end stop and hydraulic to open it

Let us say you use this for a window wiper on a truck. You want to set the start end and the finish end of the stroke,(which is about 1/4 turn). By use of the limit you set it so it just reaches the correct spot at the start and stop.

Thanks for the replies.

There is a pneumatic to open it and a spring return to close it. Lets say there is a screw stop adjustment only at one end - only at the end of the spring return stroke. Now, suppose I adjust the limit to 80 degrees, so during the spring stroke, the actuator should stop at 80 degrees. However, the technical document at the manuf. site says that there will be 5 degree overtravel, so that the actuator goes to 85 degrees.

Why this overtravel? Does this overtravel mean that the actuator goes to 85 momentarily and then returns to 80? Will this overtravel depend on the velocity with which the actuator touches the screw stop adjustment?

Back to your original post seeking a soft stop, the mechanicals can be rather abrupt at the end of the extend cycle, causing a substantial jolt at end of stroke.

Solution.. mount the cam actuator such that the end of the forward stroke is tangential ( perpendicular to the net travel) to the connecting rod, piston, collet, whatever. With controled air supply, your activity automatically decelerates, and the end of stroke velocity should approach zero nearing the end point.

Of course, available force increases dramaticly, also.

RichH

I have seen too many of these over the years. I am sure what they mean is that if the stop adjustments are backed out the actuator will travel approx. 5 deg past 90 at each end for a full travel of 100 deg.

This allows for the mechanical looseness that will develope in the actuator to valve connection coupling.

I've normally seen those adjustments screws being used with the purpose of adjusting the end of the travel according to the assembly you are installing, providing room for misalignments, building tolerances, etc.