Theatre Catalog (1947-48)

FIGURE 4—Film rails on which the film rides at the aperture are made of hardened ground stock that is then chrome plated to reduce frictional resistance, thus allowing the maintenance of adequate fension on the film during projection and insuring a steady projection without undue strain on the film perforations. Edge guiding flanged rollers are mounted at the top of the film rails and are hardened. FIGURE 5—The shutter utilized in the 12000 Series of projectors is of the barrel type, running at 1,440 x.p.m. and is, therefore, of rugged construction, with its driving shaft extended through a bearing housing at the rear of the mechanism. The film shutter assembly is supported on roller bearings mounted in the bearing housing assembly, silicone high-temperature grease being used as the lubricant. 326 tics to equal that of the standard motor normally supplied. Shutter System The shutter (Figure 5) utilized in the 12000 Series of projectors is of the barrel type, running at 1440 rpm., and is of rugged construction, with its driving shaft extended through a bearing housing, to the rear of the mechanism. The film shutter assembly is supported on roller bearings mounted in the bearing housing assembly, silicon high temperature grease being used as a lubricant. The shutter is mounted between the light source and the aperture and is of slightly more than 50 percent transmission efficiency. Of course, the inherent advantage of the barrel shutter with reference to double light cutoff is well known with respect to flicker reduction. Fire Shutter The fire shutter assembly is integral with the major shutter and functions by means of centrifugally operated weights with rawhide inserts, which transmit power between the film shutter main shaft assembly and the fire shutter shaft. The arrangement works infallibly under all conditions of temperature or oil seepage. The fire shutter is set to open or close at a film velocity of 50 feet and its roller bearings are silicone grease sealed type capable of withstanding high temperature operation. Sprockets All sprockets are hardened and ground and are in accord with the standard dimensions of the Society of Motion Picture Engineers. Lens Focusing Mount Projection lens focusing (Figure 6) is accomplished by a micrometer screw located outside the projector case with the lens focus lock located inside the projector case, guaranteeing permanent, accurate projector lens focusing. The focusing mount lens holder barrel extends through the projector case so as to allow the clamping of a preset focus ring onto the objective lens, allowing rapid replacement in focus registery when lens removal for cleaning is required. The projection lens focusing device is screw driven and slides on a rod of adequate section in a straight line motion, guaranteeing no shift of picture position on the screen during all focusing operations. Projection Lenses Projection lenses are supplied in Series II, in all focal lengths from 3% to 9144 inches and are coated so as to achieve maximum efficiency in light transmission. The formula on which these lenses have been designed have been time tested through many years of experience in the manufacture of high speed, high resolution projection lenses. The lenses are free from halo effects, and suitable interior lens barrel blackening, with the addition of coating, guarantees an efficient, high-contrast, snappy picture. THEATRE CATALOG 1947-48 <r