Page 10 - Wire Rope News & Sling Technology
P. 10

Cut end of wire rope showing shortened strand (left). Wear observed on inside of rope guard (middle). Test with paint and tape to determine
         if wire rope contacted the rope guard (right).
         continued from page 8                We wish we could tell you that the sto-  to properly use the crane and there
         rope guard with the correct part and   ry ended there, but it did not. Two days   were no more incidents.
         continue to use the crane, and this   later the wire rope broke a third time,   A Near Miss
         time it was safe for future lifts.  but this  time  it was caught  on  video.    A client mentioned that one of their
         An Incident                        So what would cause a brand new wire   mobile cranes was experiencing issues
           A wire rope broke on an overhead   rope to break?  The “Why?” was due to   with their wire rope on the drum, leav-
         crane in an automobile factory and the   the crane operator’s improper operation.  ing gaps in the lay and crushing the wire
         block came crashing down. Thankfully   The operator was using the  crane   rope as it was spooled off and on. They
         no one was hurt, the wire rope was re-  to  drag  the  load  instead  of  lifting   asked “Why?” The first thing to know is
         placed and everyone got back to work.   the load. Something he was prob-  that when a crane’s hoist rope has not
         Three days later it broke again…and   ably shown by a mentor and probably   been installed correctly, broken in and
         the block came crashing down.      thought it was a good use of time.   re-spooled, or misused the wire rope
           How could this be? It was a new wire   However, overhead cranes are only   may not properly lay on the drum. It can
         rope. Did anyone stop to ask “Why?” Was   meant to lift loads vertically.   expand away from the drum when there
         the wire rope installed properly? Maybe   As the operator dragged the steel die   is no tension on the hook, try to bunch
         there is an issue with the crane? Maybe   across the factory floor, the horizontal   up against one flange on the drum, or
         an issue with the operator? Maybe it   side pull was causing the wire rope to   react in many other undesirable ways.
         was the wrong wire rope? An investiga-  wear against the drum groove edges   So this called for a closer look.
         tion took place but they could not deter-  and the underside of the trolley. As a   First,  it  was  identified  the  type  of
         mine what happened.   The wire rope   result the wires and strands were get-  wire rope was correct by the manufac-
         was replaced and operations resumed—  ting severely worn and cut. After a few   turer specifications. The right lay rope
         but this time with a surveillance cam-  days of heavy use the wire rope broke.   was  coming  off  the  drum  in  an  over
         era on the crane.                  The operator received training on how   wound fashion as per the manufacturer
                                                                               instructions. But “Why?” was the wire
                                                                               rope not sitting properly on the smooth
                                                                               drum. To find out the source of the is-
                                                                               sue,  the  crane  was  reeved to a single
                                                                               part line and the boom extended at a
                                                                               high angle. As this happened the cli-
                                                                               ent could see the crossover, or transi-
                                                                               tion, from the first layer of wire rope on
                                                                               the drum to the second layer was not
                                                                               even—causing  the wire  rope to spool
                                                                               incorrectly as it was used.
                                                                                 They were able to fix the issue, keep-
                                                                               ing the first layer of wire rope tightly
                                                                               wound to create a firm foundation for
                                                                               the layers of wire rope that will  be
                                                                               wound  over it and checking  the cross
                                                                               over between layers to ensure that wire
                                                                               rope lays properly in  the groove cre-
                                                                               ated by the layer below. Once this was
                                                                               done, they were able to start working
                                                                               again without continued concern of the
                                                                               wire rope crushing and breaking due to
         Overhead crane  hoist drum  displays                                  winding issues.
         the  results  when the  wire rope  fails                                This type of near miss is quite com-
         and recoils back to the drum.                                         mon and as such,  the drum should
                                                                                                continued on page 12

         10     Wire Rope News & Sling Technology   June 2017
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