TrackballControls problem with rotate on one axes

When i try rotate model left/right everything works smooth, but on rotation top/bottom model “jumping, vibrate, …”. I don’t know how to describe it, you have to see it.

Why this works only on one axis.


I found something, in blender have to rotate model(press “n”, Rotation x=1, press ctrl+a => apply all transforms). Then model works fine but i don’t understand why