Hi, you're right, I'm sorry. I must be precise and careful about the reference system. What do you mean by your last observation? 

In order to get  a sliding motion between the inferior and superior blocks without separation do I need to change the direction of the force above the angle of the rigid body or it is better to switch the frictional contact between the blocks to no separation? The force thus the stress should interests not only the region surrounding the pins but also the socket of the teeth while it seems that the stress is uniform all over the two blocks. I expect regions of less stress for exemple at the teeth pockets near the simmetry region and higher stress near the pins.

Thanks a lot!