What is the easiest method to define a force constraint's coordinate system? In this example (picture), I want to align the coordinate system of the constraint with the shaft's axis, in order to be able to define torque. I attach the the model too: https://ufile.io/9hnw3
Bring up the Properties form for the force (by e.g. double-clicking on it in the model browser), then click on "Select/define the location of your Force - Moment". This should bring up the manipulator at the force application position:
Click on the ball of the manipulator, then on the axis you want to align; the axis will turn magenta:
Now click on an entity you want to align with (for example here the opposite face of the shaft is a good option):
MMB to finish. I've also attached a short video of the process. Let me know if anything isn't clear.
Can you answer me that, whether APEX capable to make dynamic simulation in which you move one of the gear and analysing the contact of the gears? I can see dynamic option, is this for investigating in time or is it just for frequency analysis?
No, Apex can't do that at the moment. The only contact currently is glued contact, and the dynamic analysis is indeed only frequency response at the moment. The capabilities you're asking about are planned for future releases of Apex. In the meantime, you'll need to export the model and run it in a separate solver (e.g. Nastran SOL400 or Marc).