Pneumatics Math Help

[s_forbes]

For a linkage like this, you need to work out how much torque the cylinder applies to the member that moves. The diagram would look like this:





The blue line shows the axis of the pneumatic cylinder. The red line in the sketch shows the distance between the axis of the cylinder and the point the mechanism rotates around. The red and blue lines are perpendicular no matter what angle the mechanism is at (that's important! and possibly the confusing part).

The torque applied to the moving member is equal to the force from the cylinder times the distance indicated by the red line. Torque = Force x Distance. It looks like you are using Solidworks to model your mechanism, I'd recommend making a simple sketch like the one above that has the correct dimensions for all of the parts, then you can measure the distance of the red line. With that you can find the torque on the moving member at any orientation you put it in.

Chris86 posted the mathematics behind this, but diagrams are a bit easier to understand if you are getting used to the concepts. Note that when the red line is the longest, you have the maximum torque applied to the mechanism! And when the red line becomes very small, you have very little torque applied to the mechanism.