Swing Bridge Rim Bearing

This model is designed to be an operable rim bearing for an N scale single track swing bridge. The part is designed to be used in a functional rotating model bridge. The design is based on the Canadian National Railways bridge in Sorel, Quebec, although it is similar to many other swing bridge bearings used around the world.
The bridge truss span itself can be made from Central Valley Model Works truss kits. Also needed for this project are the main gear and pinion (Diametral Pitch 120, 180 teeth, and 12 teeth, p/n S1268Z-120A180 and S1G84Z-120S12 from SDP-SI is used) and piers. The distance between the center of the bearing and the center of the pinion support is for the previously mentioned gear spacing.
To release the bearing, carefully cut and remove the four inner sprues connecting the rim girder with the lower raceway base. be careful not to break the bearing cage, as it is fairly fragile when unprotected. Use a metallic shaft to support and drive the swing span (0.25 dia brass pipe, hide track feed wires through pipe), and drive with a motor mounted under the layout. Carefully spray paint a thin coat while rotating the bearing to get full coverage, being attentive not to overload the wheels with paint.