An arm robot apparatus for removing workpieces such as injected molded articles includes a gripping device mounted on an arm and a race member mounted on the arm for circulating balls. The race member includes an inner part and an outer part. A ball race spindle is located inside the race member and extends along a longitudinal axis of the race member. A mounting block which is mounted on a supporting plate is attached to a first end of the ball race spindle. A second end of the ball race spindle has at least two semicircular ball races formed therein. The inner part and the outer part of the race members are interconnected in such a way that ball races of a circular cross-section are formed. The ball races are designed in such a manner that the balls arranged in the races contact the inner part and the outer part of the race member. The inner part of the race member also includes pre-tensioning channels in which balls are received for displacement and movement. The pre-tensioning channels are shaped in such a way that the balls contact the inner part and the ball race spindle. Further, the pre-tensioning channels are interconnected in a sine wave fashion and are alternatingly arranged around the race member. The balls are displaceable and moveable through the ball races and through the pre-tensioning channels around the ball race spindle. The race member is mounted to a movable plate so that movement of the movable plate causes the race member to rotate around the ball race spindle.