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         mind that wire ropes of other designs may alternatively be
         employed, e.g. those having more or fewer external strands,
         more or fewer core strands 11, and strands of non-circular
         cross-section. The core strand 11 and the external strands
         12 are each made up of bundles of individual metal wires 13
         twisted together.
           As best seen in figure 13, the outer surface 14 of the rope
         is formed by the external strands 12 separated by grooves
         15 between the strands, thereby causing the rope to have a
         spirally grooved outer surface undulating in surface height
         from the central axis 19 (see figure 15) of the wire rope. Each
         of the external strands 12 twists around the rope in spiral
         loops separated from each other along the rope by the five
         other strands  12.  In  figure  13,  one  strand  12’ is provided
         with a shaded appearance so that its loops can be identified   Figure 15: cross-section similar to that of figure 14, but taken in the
         along the rope. The lay length of such a rope is the distance   line IV-IV of figure 13.
         L along the axis or centerline of the rope required for a single
                                                              position in figure 15 than they are in figure 14 due to the fact
                                                              that the strands 12 have twisted around the center of the
                                                              rope between the respective axially-spaced cross-sections.
                                                              Therefore,  as the rope advances longitudinally (i.e. along
                                                              central axis 19) past fixed points of observation in a single
                                                              cross-sectional plane, the outer surface of the rope moves in
                                                              an undulating fashion closer to and then further away from
                                                              the points of observation due to the differences in surface
                                                              height caused by the peaks and grooves.
                                                               Figures 14 and 15 show such  points of observation  18
                                                              spaced evenly  around  the  rope  10.  If  figures  14  and  15
         Figure 13: Side-view of a wire rope showing the surface pattern pro-  are now taken to represent observations at a single cross-
         vided by external strands and grooves between the strands.  sectional plane of the rope at different times, i.e. the time
                                                              required  for  the  rope  to  advance  by the  distance  between
         strand to complete a single full circumferential spiral path   cross-sections  III and  IV  of  figure  13,  the  points  18 radi-
         around the wire rope, i.e. to progress around the rope and   ally  aligned  with  peaks  in  figure  14  (represented  by  solid
         return to the same angular position at the circumference of   circles) become points radially aligned with grooves in figure
         the rope. A conventional way of measuring the lay length   15 (shown by open circles), and vice versa, as the peaks and
         would be to measure a number of such distances (e.g. the   grooves move past the fixed points of observation. Proxim-
         three shown in figure 13) using a ruler or similar measuring   ity sensors positioned at such points of observation would,
         device, and then to calculate the average of such measure-  if  sufficiently  accurate,  record  undulating  sinusoidal-like
         ments (dividing by three in the case of figure 13).  variations in distance between the observation points and
           Due to the spirally grooved nature of the outer surface 14   the outer surface of the rope as the rope advances longitudi-
         of the rope, the outer surface is made up of peaks formed by   nally (and without rotation) along its central axis 19. Such
         the high points of the strands (i.e. the radially outermost   sinusoidal variations could potentially be used to measure
         or central points) and the grooves 15 between the strands.   the lay length of the rope.
         Figures 14 and 15 show the rope 10 at cross-sections and IV-  For example, a measurement of this kind at the topmost
         IV, respectively, of figure 13. In figures 14 and 15, the peaks   point of observation of figures 14 and 15 would provide an
         of the external strands are shown by large-headed arrows   oscillating generally sinusoidal output as the rope advances,
         16 and the grooves are shown by small-headed arrows 17.   with the distance of rope advancement causing six such os-
         It will be noticed that the peaks are in a different angular   cillations representing one lay length of the rope. Any six
                                                              such oscillations along the rope would reveal the lay length
                                                              at the corresponding positions along the rope, thus showing
                                                              local lay length measurements, or alternatively, more oscil-
                                                              lations over a longer section of the rope (or the entire rope)
                                                              could be used to provide an average lay length value for that
                                                              section or for the entire rope.
                                                              Device and method for detecting the tension on a guide
                                                              rope of a hanging scaffold in a construction shaft
                                                              Pat. 9,488,558 U.S. class B66D 1/50 Int. class G01N 3/00
                                                              Inventor: Guohua Cao, Xuzhou, CN., Yangdong Wang, Xuzhou,
                                                              CN., Zhencai Zhu, Xuzhou, CN., Weihong Peng, Xuzhou, CN.,
                                                              Jinjie Wang, Xuzhou, CN., Shanzeng Liu, Xuzhou, CN., Gang
                                                              Shen, Xuzhou, CN., Hao Liu, Xuzhou, CN.
                                                              Assignee:  CHINA  UNIVERSITY  OF  MINING  AND
                                                              TECHNOLOGY, Xuzhou, Jiangsu, CN.
         Figure 14: Cross-section of the rope taken on the line III-III of figure 13
         showing distances from fixed points arranged around the rope.  The present invention discloses a device and a method for

         54     Wire Rope News & Sling Technology   February 2017
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