Journal of the Society of Motion Picture Engineers (1930-1949)

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410 MILLER AND CRANE Octobei frame through a cam control appearing on the front of the panel) This cam then becomes a vernier adjustment of synchronization whilj the machine is running or stationary, and a range of approximately i ±2 sprocket holes is available. The filter rollers as well as. the fixed rollers in the film path are, ol course, ball bearing with pre ]; cautions taken to reduce friction] to a low value. The lower arni is provided with a fluid dashpolj for proper damping and is arl ranged to prevent spillage of thl fluid at any angle. Film rewinding is provided bjl a motor and gear-reduction unit located behind the upper pane and connected to the feed-reel 4|1 shaft with an automatic cuton assembty located in the uppei right-hand corner of the angle plate assembly. This facility provides automatic rewind once the film is threaded and rewind ing started by the operator throw' ing a small idler roller into con tact with the film. The rewinc time is adjustable between 3( seconds and one minute for 10CK feet of 35-mm film and the film velocity is reasonably constanl as provided by the usual characteristics of a high-speed, series-type motor. FILM MOTION The film propulsion of this machine is essentially the same in principle as that previously described in the JOURNAL. 2 As shown by Fig. 9, a taut film path between two 16-tooth sprockets drives a scanning drum and flywheel by belt action, and passes over two compliance) rollers, one to the left of each sprocket. One of these rollers id provided with viscous damping and this film-propulsion system hasj demonstrated its ability to suppress all mechanical disturbances genern ated in the drive mechanism as well as those caused by film splices. • Fig. 8 — Filter-roller assembly showing damping device attached to lower roller arm and locking lever which is actuated by the lower sprocket pad roller. Spring at right determines film tension in filtered path and that at left is anchored on cam for synchronization adjustment.