15 February 2019
Here is a simpler version of your model with just two gears. Look at the first Revolute. The Z axis, which is what the rotation is about, is pointing in the wrong direction! It has to be aligned with the cylindrical face axis. It is not at the center of the gear. You have to pick two faces to get it to snap to the center.
In the image below, the Reference Coordinate System under the Revolute Joint has a new center and new direction for the Principal axis.
I put a fixed support on the ID of the bottom gear since I suppressed the last gear that had a fixed joint.
You won't get good stress results with such a coarse mesh compared with a fine mesh.
If you have the Student license, you have to keep the nodes < 32,000 to be able to solve.
Just work on two gears initially.
You can use a Joint Load of type Moment instead of a Moment. Either one will work.
Insert an Contact Tool under the Connections folder. Generate Initial Contacts. Use Adjust to Touch on the contacts that are Open.
Under Analysis Settings, Turn on Auto Time Stepping and set Initial Substeps to 10.
Turn on Large Deflection.
If you have 3 gears, then you will get a better distribution of stress on the second gear. You could simulate the third gear by putting a remote displacement on one tooth face on the opposite side, and use the revolute joint on the second gear (not fixed support). This is more realistic for the idler gear.
All of this is in service to learning the process, because these are not real gear teeth, there are sharp interior corners so the exact value of stress is infinity. Do some research on Stress Singularity using the site Search capability.