Well never seen that before on a motor, usually it has a rated RPM for the rated voltage or sometimes a voltage constant. 31thousand RPM is fast
Could see if it was 3190 at 120v.
Do you have a link to info on the motors?
The problem may well be over current fault on the drive, if you are trying to push things too fast at too great an accel its possible the Gecko is tripping on over current as I think they are only 20Amp or so, not sure if they will just limit the current to that or if the motor asks for more it may trip out. If it just limits then its possible its a following error fault as the motor requires more amps than the geckos will give so it doesnt get to where its meant to be in the time frame required and thus you get a following error.
Hood