Abstract: Adjustable stops are mounted on a rotating rod, and one pivot arm of a linked pair extends into an interference position such that one stop will strike it. The linkage draws the second arm into interference position if the first arm is displaced from it. Each pivot arm will brake the stop if struck from one direction and will be displaced, drawing in the other pivot arm, if struck from the opposite direction. The pivot arms react oppositely to being struck from each respective direction of rotation. Thus, continued rotation of the rod in one direction results in a stop striking a pivot arm suitably to brake the stop, with the permitted arc of rotation determined by relative adjustment of the stops.