Page 28 - Wire Rope News & Sling Technology
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continued from page 26
         of the Bessemer process in 1855 as well
         as the development of the open hearth
         process in 1862. These steam ploughs
         gave us the origin of the term plough or
         plow steel as it is known today.
           All of these early ropes were made by
         hand on rope walks where a number of
         wires were laid out before being twisted
         into strands by men walking along with
         a device for rotating one end of the group
         of wires. The process was then repeat-
         ed on groups of strands to form a rope.
         The rope-making process was gradually
         mechanized and sped up to the rates in
         excess of 5,000 feet of finished rope per
         hour and in continuous lengths of 40,000
         feet to 50,000 feet or more.
           The call for ropes with higher break-
         ing strength and greater flexibility in-  Facade of the Washburn & Moen Manufacturing Co. as it appears today.
                                            Photo courtesy of Peggy Clark, Photographer, Washburn University
         evitably led to the design of ropes with
         a higher number of wires. Strands with   not manage the slopes because of their   side wires cross the heart wires.”
         6 instead of 4 outer wires were devel-  own weight. Therefore the so-called   Seale  influenced  a  rope  manufac-
         oped which were twisted around a cen-  cable cars were used. As the situation   turer  to  produce  a  rope  according  to
         ter  wire  of  the  same diameter. This,   required, their cars were attached to or   his invention. He used this rope on the
         however, meant a partial  change for   disconnected from endless, circulatory   Cable Car which he operated. The first
         the worse  of the original  invention  of   underground traction ropes.   rope manufactured from parallel lay
         this type of wire rope. The center wire   The heaviest cost factors of the cable   strands achieved an excellent  service
         lay stretched in  that strand whereas   cars consisted of the wire ropes them-  life. Seale granted a number of licenses
         the other wires formed a helix.    selves and the repair costs of rope fail-  for  his  invention  which  made his  de-
           As a result the rope elements were   ures. Hence Tom Seale tried to improve   sign widely known.
         of different lengths and had a different   the work life of the ropes. He found out   In the period following, those manu-
         shape in the rope. No longer was it pos-  that the ropes failed because of inner   facturers who were not given a license
         sible to inspect all the wires because   wire  breaks,  which  he  first  thought   tried out  various  strand designs  to
         the central wire  remained concealed   were  caused by the lack  of interior   elude Seale’s  patent. Therefore,  the
         from any angle.                    flexibility. He was sure to remedy that   1880s were a period when the wire rope
           The next step was the introduction   disadvantage  by using strands with   industry  experimented excitedly and
         of multilayer strands. Around a strand   strong,  abrasion-resistant outer and   the most unusual designs were tested.
         of one  plus six wires,  another  layer   thin  flexible  inner  wires.  He  got  hold   Again and again the attempt was made
         of 12 wires of the same diameter was   of wire samples of different diameters   to manage with only one or as few wire
         twisted. In order to achieve a uniform   and manufactured different strand   diameters as possible.
         loading of all the elements one saw to it   samples by hand.            Only a few years after Seale’s practi-
         that the wires of the latter layer were   During  his experiments  it happened   cal application James Stone, an Ameri-
         of precisely the same length as those of   again and again that the thicker outer   can engineer working for the rope man-
         the first layer. This was just the case if   wires  fell  into  the  valleys  of  the  wire   ufacturers  Washburn & Moen (photo
         the wires of both layers were twisted at   layer  underneath  and  then  tended  to   above)*, detected  the weak point of
         the same angle to the strand axis.  follow the helix of that layer. Seale no-  Seale’s patent: Seale had confined him-
           Unluckily  this  choice  of lay lengths   ticed that a strand of this design, with   self to strands whose outer wires were
         generated innumerable wire crossovers   the same number of wires in both lay-  thicker than those of the layer under-
         in the strands, which, due to the high   ers and with the right diameter propor-  neath. James Stone constructed a con-
         local pressures, led to the premature   tion of the wires, resulted in a very solid   ventional 19-wire strand in the paral-
         failure of the wires. Without being real-  strand which was also very round. He   lel lay and filled the resulting cavities
         ized, this step of development resulted   also detected that he could avoid the   with  filler  wires.  In  1889  Stone  ob-
         in another partial deterioration of the   crossovers within the strands if the wire   tained a patent for this strand design
         original invention. Probably the most   layers were arranged in a parallel way.  which today – over one hundred years
         relevant  further  development of  wire   As he explained it in his 1855 patent   later – remains perhaps the most used
         rope was the invention of the parallel   document: “This gives great flexibility   multilayer strand grouping worldwide.
         lay strand by Tom Seale in 1884.   to the  strand and in  the cable,  with   In all probability, the Warrington
           Tom Seale was Director of the Cable   solidity and compactness.  While  the   strand was developed  between some-
         Car which was also owned by the Gov-  wires of the outside or covering of the   time in the mid-1880s. Its inventor is
         ernor  of  California,  Leland Stanford.   heart lie upon a comparatively smooth   unknown  as is even the origin of the
         This cable car, named California Street   [surface]  and not upon a surface  of   name.  With  a precision  that was  suf-
         Line, remains in operation. The steep   ridges, as in other constructions [such   ficient for the requirements of the time
         ascents on the streets of San Francisco   as] where there exists considerable dif-     continued on page 30
         made it hopeless for the horses to pull   ference between the lay of one surface   *Editors note: Also see our article about
         the trams. Even steam engines  could   and that of the other, or where the out-  Ichabod Washburn on page 18.

         28     Wire Rope News & Sling Technology   April 2018
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