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Universal Joint

Basic Machines - Intro to machines and motion theories
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Figure  11-15.-Sleeve  coupling. pivot, and the two links connect at two points in different directions  from  the  pivot.  By  properly  locating  the connection points, the output links can move in any desired  direction. All  linkages  require  occasional  adjustments  or repair,  particularly  when  they  become  worn.  To  make the  proper  adjustments,  a  person  must  be  familiar  with the basic parts that constitute a linkage. Adjustments are normally  made  by  lengthening  or  shortening  the  rods and shafts by a clevis or turnbuckle. COUPLINGS The term coupling applies to any device that holds two parts together. Line shafts that make up several shafts of different lengths may be held together by any of several types of shaft couplings. SLEEVE COUPLING You may use the sleeve coupling (fig. 11-15) when shafts are closely aligned. It consists of a metal tube slit at each end. The slitted ends enable the clamps to fasten the sleeve securely to the shaft ends. With the clamps tightened, the shafts are held firmly together and turn as one  shaft.  The  sleeve  coupling  also  serves  as  a convenient device for making adjustments between units. The weight at the opposite end of the clamp from the screw merely offsets the weight of the screw and clamp  arms.  Distributing  the  weight  evenly  reduces  the shaft vibration. OLDHAM  COUPLING The  Oldham  coupling,  named  for  its  inventor, transmits rotary motion between shafts that are parallel but not always in perfect alignment. Figure  11-16.-Oldham  coupling. An Oldham coupling (fig. 11-16) consists of a pair of disks, one flat and the other hollow. These disks are pinned to the ends of the shafts. A third (center) disk, with a pair of lugs projecting from each face of the disk, fits into the slots between the two end disks and enables one shaft to drive the other shaft. A coil spring, housed within the center of the hollow end disk, forces the center disk against the flat disk. When the coupling is assembled on the shaft ends, a flat lock spring is slipped into the space around the coil spring. The ends of the flat spring are formed so that when they are pushed into the proper place, the ends of the spring push out and lock around the lugs. A lock wire is passed between the holes drilled  through  the  projecting  lugs  to  guard  the assembly. The coil spring compensates for any change in shaft length. (Changes in temperature may cause the shaft length to vary.) The  disks,  or  rings,  connecting  the  shafts  allow  a small amount of radial play. This play allows a small amount of misalignment of the shafts as they rotate. You can easily connect and disconnect the Oldham type couplings to realign the shafts. OTHER TYPES OF COUPLINGS We use four other types of couplings extensively in naval  equipment: 1.  The  fixed  (sliding  lug)  coupling,  which  is nonadjustable;  it  does  allow  for  a  small  amount  of misalignment in shafting (fig. 11-17). 2.  The  flexible  coupling  (fig.  11-18),  which connects two shafts by a metal disk. Two coupling hubs, 11-10







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