Reaction moment at the constraint

Hello all,

I am currently calculation a body in which i am applying a moment to a gear and the shaft of that gear is fixed in rotational direction.

How can i measure or detect the reaction at the shaft in terms of moment.

I have used cylindrical co-ordinate system to constrain the rotation and just defining a measure does not work if the constraint is applied other than WCS.

Please put some light to solve this problem.

Thank you