Page 70 - Wire Rope News & Sling Technology - October2019
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INVENTOR’S CORNER
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         Figure 26: Perspective view of a winch for the hoisting device.
         the travelling block 15, acting as a counterweight for the top
         drive 7, and the single-layer winch 5 being provided at the
         second side of the derrick. As also discussed above, the em-  Figure 28: Third schematic side view of a hoisting device.
         bodiment where the travelling assembly has been split with
         one part acting as counterweight for the other, also entails   5 with a winch drum 51 used in a system 1 according to the
         the possibility of using different qualities and thicknesses of   present disclosure. The shown single-layer winch 5 accommo-
         the two portions 31, 33 of the wire rope 3. The first portion   dates four parallel wire ropes 3 extending from the single-5
         31 of the wire rope, directly connecting the travelling block   layer winch to the top drive 7, where the latter is not shown
         15 and the top drive 7, will have to carry heavier weights   in this figure. The use of parallel wire ropes 3 and the single-
         than the second portion 33 of the wire rope 3, the second   layer winch 5 itself were discussed in PCT/NO2014/050113,
         portion 33 running through multiple-part system connecting   and reference is made thereto for an in-depth description.
         the travelling block 15 to the single-layer winch 5 as will be   Figure 27 shows a system 1 where the second portion 33 of
         described below with reference to figures 27 and 28. The top   the wire rope 3 connects the single-layer winch 5 to the travel-
         drive 7 and the travelling block 15 are connected to the der-  ling block in a two part-system. The second portion 33 of the
         rick 9 by means of not shown dollies.                wire rope is reeved directly from the single-layer winch 5, over
           Figure 26 shows a more detailed view of a single-layer winch   the travelling block 15 and to an anchor 17. This means that
                                                              the single-layer winch 5 have to be dimensioned to handle half
                                                              the weight of the system’s capacity. For instance, in a 1500 ton
                                                              system, the single-layer winch 5 will have to be dimensioned
                                                              for lifting 750 tons. In this two-part 1500 ton system, the first
                                                              portion 31 with six parallel steel wire ropes 3 would have to be
                                                              made with a thickness of approximately 90 millimeters, while
                                                              the second portion 33 of six parallel wire ropes 3 would have to
                                                              made with a thickness of 65 millimeters.
                                                               In  figure  28,  the  second  portion  33  of  the  wire  rope is
                                                              shown connecting the single-layer winch 5 to the travelling
                                                              block 15 in a three-part system, where the second portion
                                                              33 of the wire rope also is reeved over a second elongated
                                                              hoisting member guide means 19 in the form of a sheave. In
                                                              this embodiment, the single-layer winch 5 only have to be
                                                              dimensioned for lifting one third of the total load capacity of
                                                              the system 1. Different braking requirements will typically
                                                              decide which version to choose. In a three-part 1500 ton sys-
                                                              tem 1 with six parallel wire ropes 3, the first portion 31 of
                                                              the parallel wire ropes 3 would have to be made with a thick-
                                                              ness of approximately 90 millimeters, while the second por-
                                                              tion 33 of the parallel wire ropes 3 would have be made with
                                                              a thickness of 53 millimeters. With an D/d ratio in the order
                                                              of 60 for both the first portion 31 and the second portion 33
                                                              of the wire rope 3 in a system 1 according to the present
                                                              disclosure, it has been found that it is possible to extend the
                                                              lifetime of the wire rope 3 up to the order of five years, which
         Figure 27: Second schematic side view of a hoisting device.  is a significant improvement from today’s two weeks. WRN

         70     Wire Rope News & Sling Technology   October 2019
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