2 answers

• 
  Darren S over 1 year ago

  Try drawing the inner race and the outter race seperatly and which ever part is going to turn put the balls on that one. It won't matter that the balls themselves are not turning they will look like they are. Then just constrain the inner and outter together. Hope this is clear and helps.

• 
  Mile over 1 year ago

  There might be fancier ways of doing it, but the one I have used in Motion Studies, is to make an invisible part, that controls the other part(s).
  In this case, I would make an extra part with the shape of a box through the rolling bearing with lots of square holes in it (one hole for each ball and in the position of each ball). In the picture you can see the balls (grey), one of the bearings (white) and the extra part (light red). For each ball I would mate the face to be tangent to two faces in the hole to constraint both the diameter and the position of the ball (as can be seen from the picture). In the Motion Study I would turn the box around the axis (with a rotational motor) to get the balls to move, then go back on the timeline and hide the box - thus the balls' motions can be controlled fully by the now invisible part.

  Added images