Abstract: A projector for motion picture film includes a servo motor which is controlled to advance film frame by frame to a projection station. A capstan on each side of the projection station is controlled to maintain film loops of substantially constant size and an associated reel motor delivers film to and takes film from each capstan. Each associated capstan and reel motor are controlled so as to maintain substantially constant tension on the film. A film guide defines the projection station and also includes provision for masking peripheral areas of each frame. Each capstan and an associated pinch roller are designed so as to eliminate creeping of film from between the two. A circuit for controlling the reel motors is arranged to permit fast winding of film directly from one reel to the other with an automatic braking feature.

Abstract: A commutated electric motor, which motor is cooled by the fluid which it pumps. The motor has a molded end cover construction, the material being the bearing material, and providing for guiding of the brushes. Torsion springs are utilized as the sole biasing means and current carrying members for the brushes. Also, the fluid is pumped along a closed channel structure and directed against the brushes to increase endurance.

Abstract: A tractor belt adapted to be trained over and driven and supported by sprockets in a mechanism for advancing and positioning a strip of material having hole-in-line perforations, the belt comprising a wire-cored band having perforation engaging lugs integral with and projecting from one surface of the band and sprocket engaging lugs integral with and projecting from the opposite surface of the band. A method for making such a belt.

Abstract: A method of assembling a dynamoelectric machine with the desired concentricity of the stator and rotor by mounting rotor bearings in loose supporting relationship with bearing brackets having a fixed relationship with the stator, and then locating the bearings in their respective brackets to support the rotor concentrically of the stator, and finally fixedly attaching the bearings to their brackets in their concentrically supportive positions.