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         tioned over a second location to drop off the payload.
           The swing-circle assembly 56 also carries an operator’s cab
         62, a diesel engine 63, and a hydraulic pump 64 driven by
         the diesel engine. The hydraulic pump 64 powers the swing-
         circle assembly 56, the hoist mechanism 55, the boom host
         winch 59, and an auxiliary hoist mechanism 65.
           In the crane 50, the hoist rope 53 is a main hoist wire rope,
         and the hoist mechanism 55 is a main hoist winch. A live
         end of the main hoist wire rope 53 is secured to the main
         hoist winch 55, which draws in the main hoist wire rope 53
         to lift the payload 54. A dead end 66 of the main hoist wire
         rope 53 is secured to the boom 52. A hoist block 67 carrying


                                                              Figure 16: More permanent mounting of the first kind of elastomeric
                                                              load compensator under the boom of the crane.
                                                              the (sometimes very high) liftoff velocity required to avoid
                                                              payload re-contact with the deck of the floating vessel, as
                                                              well as provide compensation for deck heave. The re-contact
                                                              scenario involves the deck moving down at the moment the
                                                              payload is picked up off of the deck. The payload then has
                                                              a certain amount of time to get out of the way before the
                                                              deck comes back and hits it. This time allowance dictates a
                                                              hoisting velocity. The elastomeric load compensators of the
                                                              present disclosure have been designed to resist the “impact”
         Figure 14:  Side view of a conventional pedestal-mounted  offshore   from the upward-moving hook meeting the downward-mov-
         crane having a lattice-frame boom.                   ing payload, rather than typical heave applications, where
                                                              load re-contact is not such a concern.
         the main hook 68 attaches the main hoist wire rope 53 to the   Figure 15 shows an elastomeric load compensator 80 con-
         payload 54. For example, the hoist block 67 provides a maxi-  figured  for  quick  mounting  and  dismounting  from  an  off-
         mum lift of 50 short tons (45.4 metric tons). The main hoist
         wire rope 53 runs over a boom point sheave assembly 69 and
         over a sheave assembly 70. The combination of the sheave
         assembly 70 and the hoist block 67 organizes the main hoist
         wire rope 53 into a four part reeving so that the tension on
         the main hoist wire rope 53 is about one-quarter of the ten-
         sion applied on the main hook 68 from the payload 54.
           The crane 50 also has an auxiliary hoist wire rope 71. A live
         end of the auxiliary hoist wire rope 71 is secured to an auxiliary
         hoist winch 65 mounted to the base 51. A dead end of the aux-
         iliary hoist wire rope 71 is secured to an overhaul ball 72. The
         auxiliary hoist wire rope 71 runs over the boom point sheave
         assembly 69 and over a sheave 73 at the distal end of the jib 61.
           It is desired to use elastomeric load compensators for load
         compensation of a crane, such as a crane of the kind shown
         in  figures  13  and  14.  The  load  compensators  may  handle

                                                              Figure 17: Alternative way of using the first kind of elastomeric load
                                                              compensator mounted under the boom of the crane.

                                                              shore  crane.  In  the  example  of  figure  15,  the  elastomeric
                                                              load compensator 80 has been mounted to the crane 20 of
                                                              figure 13, although a similar elastomeric load compensator
                                                              can be just as easily mounted in the same way to the crane
                                                              50 of figure 14.  As shown in figure 15, the dead end 32 of
                                                              the main hoist wire rope 23 has been removed from a load
                                                              cell mount 81 on the underside of the boom 22 and attached
                                                              to a first steel eyelet 82 of the elastomeric load compensator
                                                              80. A link 83 has been added to attach a second steel eyelet
                                                              84 of the elastomeric load compensator 80 to the load cell
                                                              mount 81. Therefore tension in the main hoist wire rope 23
                                                              is applied to the elastomeric load compensator 80, and the
         Figure 15: First kind of elastomeric load compensator installed in the   elastomeric load compensator reacts to the applied tension
         crane between the boom and a dead end of a main hoist rope.  by elongating so that the distance between the first eyelet

         64     Wire Rope News & Sling Technology   August 2017
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