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

Record Details:

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April, 1930] Fl^XIBI^ DRIVE SHAFTS 387 diameter rubber covered casing. For cameras used without a soundproof booth, the rubber covered casing is the best as it will deaden any slight noise caused by the rotation of the flexible shaft. Somewhat the same effect can be obtained with the metallic casing, by covering it with a light, flexible rubber tubing. It is also advisable to grease the flexible shaft occasionally with a good grade of light grease. Attachment of the flexible shaft assembly to the motor is usually made with a special ball bearing motor coupling manufactured for this purpose and designed to fit the standard end fittings furnished on stock */4 in., 5/ie in., and 3/g in. diameter flexible shaft combinations and their respective casings. These couplings are also supplied in various sizes to fit standard size motor shafts. Due to the many types of cameras, there is no standard adapter made for attaching the flexible shaft drive to the camera. It is, however, a simple matter to have one made to fit both the camera drive shaft and the standard end fittings provided on the flexible shaft and casing. Flexible shaft camera drives are usually used in lengths from 3 ft. to 6 ft. and in special cases up to 10 ft., the length being governed of course by the position of the motor. TURNTABLE DRIVES Our next problem is the turntable for synchronized sound disk records. It is customary to connect the turntable direct to the projecting machine by any one of a number of methods. Those most widely used are: (1) the direct shaft drive where the turntable is usually mounted directly on the projection machine; (2) the solid shaft drive with one or two universal couplings ; (3) the short flexible solid rubber coupling drive; (4) the flexible shaft drive. A perfect turntable drive should be all of three things. It should be vibrationless, provide a positive drive, and allow for flexibility in installation. Of the four drives listed above, the flexible shaft drive is the only one which fulfills all three requirements. Vibration is experienced with solid shafts if they are not properly installed; also there is no flexibility in installation as the position of the turntable cannot be changed. Vibration is the main disadvantage of universal joints and here also we have little opportunity to change the location of the turntable. The flexible rubber coupling is partially satisfactory but is subject to deterioration and cannot be used in lengths over 6 in. However, when we consider the flexible shaft drive we