Page 30 - Wire Rope News & Sling Technology
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         it could be manufactured from a center
         wire  and two more wire  layers of the
         same diameter. The spaces in the outer
         layers could be filled with a wire of a
         different dimension.
           The  first  drawing  of  a  Warrington
         strand can be found in the notebook of
         the German emigrant John  Roebling
         who  made a name  for  himself  as  the
         designer  of the Brooklyn  Bridge and
         founder of the American wire rope in-
         dustry. At the bottom of the drawing of
         the strand Roebling had written: “This
         is the true proportion.”
           John Roebling died 15 years prior
         to Seale’s invention of the parallel lay
         strand. Maybe if he’d realized the im-
         portance  of  his  sketch  Roebling  –  not
         Seale – would have gone down in the
         history of technology as the inventor   Second floor of the Roebling Machine Shop, 1907.
         of the parallel lay strand. Perhaps the   East River  Suspension  Bridge, which   than  iron  wire  and  it  was  difficult  to
         name, Warrington strand goes back to   came to be called Brooklyn Bridge.   work it into a helix.
         the city of Warrington in Great Britain   The bridge  was opened  in 1883  and   Pre-formation as we know it today was
         which in the 19th century was the home   was then the highest building of the   not invented before the 1920s. Ameri-
         of two wire rope factories, the White-  Western Hemisphere. The ropes were   can Chain & Cable faced the problem of
         cross Company and the Warrington Wire   manufactured at the rope factory of John   having to produce 8 million end connec-
         Rope Company. Unfortunately the War-  Roebling, who, as mentioned above, was   tions per year for the brake cables of au-
         rington strand in Roebling’s notebook or   also the designer of the bridge, though   tomobiles. As the ropes would open up
         in catalogs of the two firms contain no   he did not live to see the completion of   and unlay after cutting they had to be
         hints that the Warrington strands were   his world-famous bridge project. Son   secured with the help of seizings, which
         in reality manufactured in Warrington.  Washington Roebling and subsequently   was very costly. So the company tried to
           The development of high-tensile steel   – when the little-understood occupation-  find means and ways of preventing the
         wires  was another landmark in the   al hazard of Caisson’s Disease or “the   wire ropes from opening up.
         history  of wire  rope.  The  Englishman   bends” made him a virtual invalid – his   In 1922 an employee of the said com-
         James Horsfall  was  granted a patent   wife Emily Roebling were responsible for   pany,  named Connor,  developed the
         for  the  heat treatment of  wires.  His   making the undertaking a reality.   “quill” a device that is still widely used
         patent document was a masterpiece of   Suspender cables lasted over 100   in the USA today.  In 1925  the self-
         disguise, and consequently for a long   years before being replaced, while the   employed engineer  Briggs,  retained
         time his competitors were unable to   original  main  cables  are  still  in  use.   by American Chain & Cable invented
         copy his  technique.  Until today heat   The original main cables remain in use   a different solution: He developed the
         treatment of wires is called “patenting”   to this day. Using steel wires instead of   preforming head with  rollers  which,
         after this mysterious patent.      iron wires caused some unprecedented   virtually unaltered, is still in use round
           Steel  wire  for  wire  ropes  was  first   problems for the wire ropers: high-  the globe. American Chain and Cable
         used for the suspension  ropes of the
                                            tensile steel wire was much more rigid   granted licenses  for the technology of
                                                                               pre-formation to rope factories all over
                                                                               the  world,  and this  business  was  so
                                                                               lucrative that they stopped  their own
                                                                               rope production  and concentrated  on
                                                                               training the license holders and collect-
                                                                               ing the license fees.
                                                                                 This was because the licence agree-
                                                                               ments stated that the license holder had
                                                                               to charge a price supplement on a pre-
                                                                               formed wire rope of 25%, of which he had
                                                                               to pay over the major part to American
                                                                               Chain and Cable. However, preforming
                                                                               wire ropes became commonplace very
                                                                               soon, and  now  the rope manufacturer
                                                                               had a problem when a customer ordered
                                                                               a rope that was not preformed because
                                                                               such a rope, for which he would get less
                                                                               money was more expensive to produce
                                                                               than a preformed one because the pre-
                                                                               forming  head had  to  be  removed  from
                                              Roebling’s Steel Mill (Melt Shop), 1926.
                                                                                                continued on page 55
         30     Wire Rope News & Sling Technology   April 2018
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