Page 59 - Wire Rope News & Sling Technology - August 2018
P. 59

flexibility when passing over the one or
         more  sheaves  18  to  provide  low  bend-
         ing stresses, meet belt life requirements   SLINGUARD PROTECTORS
         and have  smooth  operation,  while  be-
         ing sufficiently strong to be capable of
         meeting strength requirements for sus-
         pending and/or driving the elevator car                     “Clutch Action”
         12. The jacket 34 could be any suitable
         material, including a single material,
         multiple materials, two or more layers                “The Only Proven Protection
         using the same or dissimilar materials,              For Your Products and Slings”
         and/or a film. In one arrangement, the
         jacket 26 could be a polymer, such as an              Extends Sling Life - Reduces cost
         elastomer, applied to the cords  32 us-
         ing, for example, an extrusion or a mold
         wheel process. In another arrangement,                  Sleeves, Wraps, Pads
         the jacket  34 could be a woven fabric
         that engages and/or integrates the cords                          & Blankets
         32. As an additional arrangement, the
         jacket  34 could be one or more of the
         previously  mentioned  alternatives  in
         combination.                                                         Available From:
           The  jacket  34 can  substantially re-
         tain the cords 32 therein. The phrase                   THE VERNON CORPORATION
         substantially retain means that the                        P.O. Box 246 • 400 N. Yankeetown Road
         jacket  34  has  sufficient  engagement                           Boonville, Indiana 47601
         with the cords  32 to transfer torque
         from the machine 50 through the jacket
         34 to the cords 32 to drive movement of          (800) 897-5584
         the elevator car 12. The jacket 34 could
         completely envelop the cords 32 (such
         as shown in figure 7), substantially en-
         velop the cords 32, or at least partially
         envelop the cords 32.
           Referring  to  figure  9,  a  fault  detec-
         tion unit 52 is electrically connected to
         a plurality of cords 32 of the belt 16. The
         fault detection unit 52 is connected to a
         terminated portion of the belt 16, for ex-
         ample, at an end 24a and/or 24b of the
         belt 16 located at the support 26 (shown
         in figure 5). The cords 32 are electrically
         connected to the fault detection unit 52
         in  a  Wheatstone  bridge  configuration.
         In one embodiment, as shown in figure
         9, each cord 32a, 32b, 32c and 32d of
         a four-cord 32 arrangement forms each
         leg of the Wheatstone bridge. Cord ends
         32A and  32B are connected are con-
         nected via input leads  54, while cord
         ends  32C and  32D are connected via
         input leads 54. Other ends of cords 32a
         and 32b, referred to as 32A’ and 32B’
         are connected via output lead 56, while
         ends of cords 32c and 32d, referred to
         as 32C’ and 32D’ are also connected by
         an output lead 56. The resulting bridge
         circuit 58 is shown in figure 10.
           Each leg 60 of the bridge circuit 58
         is an LCR circuit allowing for mea-
         surement of complex impedance of the
         legs  60 or alternatively resistance of
         the legs  60. An excitation voltage is
         applied across the bridge circuit  58
         via the input leads 54 from the fault
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