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# How do I constrain/load a lever?

#### babbel

##### New member
hi, I'm pretty new to Pro/mechanica and am struggling on a pretty fundemental problem. I have a lever with a pivot in the middle. How can I run an analysis on it?

I know you can't put rotational constraints on solids so how do I constrain it at the pivot? (There is a hole in the model where a shaft will go).

Jonathan,

First, if you are going to run a stress analysis, you system needs to be in static equilibrium. That is, if you apply a force on the top of the lever there must be another force on the pivot location(or somewhere else)that will counteract the apply force in order to keep from moving (static equilibrium).Thereforeif you allow the lever to rotate then it is no longer instatic equilibrium. Therefore, you must constraint the pivot hole in all its degrees of freedom.

However, here is the solution to your question. if you want to allow the pivot hole to rotate with respect to its axis, then you need to create a cylindrical coordinate systemalign withthe pivot hole axis. Thenuse that Cylindrical coordinate system to create the constraints. Instead of having x, y, and z constraints the new constraint window will show R (Radial),T (Tangential),Z (direction of the pivot hole axis). Using this new coordinate system you must set the Tangential degrees of freedom free. By doing that you will allow the part to rotate with respect to the pivot point.

If you have more questions send me a picture of your model so I may have a better understanding of what you are trying to do.

Luis

Thanks Luis. I tried your suggestion with the cylidrical coords and it worked a treat. Nice one.