The center (by-pass) blade is attached to the full-length ½" diameter shaft. The hot deck and cold deck blades (at either side of the by-pass) are secured to larger hollow shafts that ride on bearings supported by the ½" diameter shaft. They are spring loaded to the closed position and are opened by a lever attached to the ½" diameter shaft.

A full sequence of control occurs during 90° of rotation by the ½" diameter shaft. The sequence given is clockwise (facing the shaft end) when actuated from either side of the damper.