International projectionist (Jan 1963-June 1965)

in the DeVry and, of course, in that "Old Reliable." the Western Electric (ERPI) universal projector base. Failure of chain takeup drives must indeed be very rare, inasmuch as this writer, who has seen just about everything that can go wrong in a projection room, has never heard of such a thing happening. It is only necessary to inspect the chain for worn or weak links every year or two, and to keep the chain and drive sprockets clean and lightly lubricated. Gear grease should be used on chains — grease heavy and sticky enough not to be thrown off when the machine is running. Among the many modern features of the Philips Norelco 70 35-mm projector is the elimination of all takeup belts and chains. A vertical drive-shaft extends from the mechanism down into the lower-magazine compartment where the friction-disc clutch is located. A universal-shaft coupling insures smooth, vibrationless operation; and simple bevel gears transmit the rotation of the shaft to the clutch which is essentially the same as the type American projectionists are already familiar with in the Simplex and other popular machines, and which is adjusted for tension in the same way. Individually Motorized Takeups The Bauer U2 and Cinemeccanica Victoria-X 70 '35-mm projectors employ separate drive motors for their takeups. (The two motors of the Philips Norelco are both for driving the projector, itself, one motor being used for a film speed of 30 frames per second, and the other for the standard 24frames/sec. rate.) In the Bauer and Victoria, therefore, there is no mechanical connection between the picture-sound mechanism and the film takeup. The Bauer has an unusual friction-clutch arrangement. It is designed so that the weight of the film roll, itself, determines the degree of coupling through the clutch — the more film on the lower reel, the greater the friction of the power-transmitting clutch. This is intended to ease the strain on the film at the beginning of the run, and yet insure fail-proof rotation of the heavy reel as the showing goes on. Several other manufacturers prefer simple arrangements. The large lever visible in the photograph of the Bauer U2 takeup assembly (Fig. 6) must be inserted in one of the five bore-holes in such a way that the white line on the lever stands vertical. In order to guarantee non-retarded starting of the large heavy reels when switching the projector motor on, a relay switch magnet drawing its current supply from the 60-volt rectifier for the changeover is momentarily switched in while the projector motor speeds up. The "in-circuit time" of the magnet can be altered at the slotted brass pin. on the delay relay. Although correctly set at the factory, adjustment of this device has sometimes been found necessary to prevent film breaks in the lower magazine. Adjustment of the tension of the friction-disc clutches of both the Philips Norelco and the Cinemeccanica Victoria-X is completely orthodox, and similar to that of the familiar Simplex. (The Victoria utilizes a separate takeup drive motor, but the gearing is direct and simple. ) A small amount of gear grease should be applied to the takeup drive gears of the Norelco once every three months. Servicing Simplex-Type Takeups The grimy, maladjusted takeup assemblies of older projectors are fortunately easily restored to top-notch condition. Even if a takeup unit looks okay on the surface, an overhaul is called for if the film winds up FIG. 4 — Closeup of the Philips Norelco takeup drive. The friction-disc clutch is geared directly to the mechanism drive. Adjustment is simple, upkeep negligible. Note the centrifugal governor which operates a relay for shutting the projector down should motor speed decrease through failure of the electric power. FIG. 5 — The Bauer U2 70/35-mm projector employs an independent drive motor for the film takeup, thus eliminating all gearing, pulleys, belts, etc. which would otherwise be present. The Cinemeccanica Victoria-X also has a motorized takeup. International Projectionist November, 1963