Clarification: Loads/BCs

What is meant by Zero displacement? Does it apply to the whole gear or it's bore?
Same question for the rest of "Constraints".
I am trying to load the example gear as a pair and solve 3 tooth model (3D). Seems to take forever and I end up killing the job.
It is running in the virtual box with 4GB mem of its own. Does seem to use only about 3GB and no swap, but taking too long.
Would help to have file with progress periodically dumped so we can see what is going on. Where are the getfem input files? Did not see them in /tmp.
Also an example in 2D would be useful. I also tried that, getfem finished very quickly but with zero displ + stresses :-(
Thanks again for the software. Very unique and useful for mech engineers involved with gears.