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         Rope hoisting system
         Pat. 9,790,070  U.S. class B66F 19/00  Int. class B66F 19/00
         Inventor: H{dot over (a)}kon F., Bergan, Kristiansand, NO.
         Assignee: Cameron International Corporation, Houston, TX.
           Various hoisting systems having an assembly for gripping
         a hoisting line are provided. In one embodiment, an appara-
         tus includes a hoisting system having a plurality of sheaves
         and a chain reeved about the plurality of sheaves. The chain
         includes links having clamps for selectively gripping a hoist-
         ing line. The hoisting system also includes a closing track
         having a travel path for the clamps of the links of the chain.
         This travel path includes an opening between two opposing
         surfaces and at least a portion of the opening has a width be-
         tween the two opposing surfaces narrower than the widths
         of the clamps, when open, such that, when the links pass
         along the travel path of the closing track, the two opposing
         surfaces cause the clamps to close about the hoisting line.
         Additional systems, devices, and methods are also disclosed.
           A hoisting system 10 is illustrated in figure 17 in accor-
         dance with one embodiment. In this example, the hoisting
         system 10 is embodied in a crane 12, but the hoisting sys-
         tem 10 could take other forms in different embodiments. The
         crane 12 is shown in figure 17 as a pedestal crane mounted
         on a deck 14. The deck 14 is part of a floating vessel (e.g., a
         drillship or semi-submersible drilling rig) in certain embodi-
         ments. When used with an offshore drilling or production
         platform, the hoisting system  10 can be used to facilitate
         well completion and intervention operations.         Figure 18:  Gripping assembly including a chain with links having
                                                              clamps for gripping and pulling the hoisting line.
           The depicted crane 12 is a knuckle-jib crane with a main
         beam 16 connected to a second beam 18. The illustrated sys-  late). In other embodiments, the hoisting line 20 could be pro-
         tem 10 includes a hoisting line 20 reeled out from a rotat-  vided as a metal cable (e.g., a braided, steel-wire-strand rope)
         able drum 22 on the crane 12. The hoisting line 20 is reeved   or a wire rope (e.g., a rope having a fiber core with strands of
         through  sheaves  24 and  26,  and a hook  28 on  the end of   steel wire wound around the core) instead of a fiber rope.
         the hoisting line 20 can be used to connect the hoisting line   In some hoisting systems, the weight of a load is carried
         20 to a load (e.g., wellhead equipment or other well compo-  by one or more sheaves via the hoisting line. Wire ropes or
         nents). Once connected, the hoisting line 20 can be reeled   metal cables can be used to support heavy loads. But in some
         in or reeled out from the drum 22 to raise or lower the load.  of these instances, such as when lowering equipment in deep
           Any suitable hoisting line 20 could be used with the hoist-  waters to a subsea wellsite far below the surface,  a large
         ing system 10. In some embodiments, the hoisting line 20 is a   portion of the hoisting capacity of a system is used by the
         non-metallic line, such as a fiber rope. For instance, the hoist-  weight of the wire ropes or metal cables themselves. In other
         ing line 20 can be made of natural fibers (e.g., hemp, cotton, or   instances, fiber ropes could be used. When the weight of a
         jute) or synthetic fibers (e.g., polyester, nylon, polypropylene,   heavy load is carried by a sheave via a fiber rope, however,
         poly-paraphenylene terephthalamide, or polyester-polyary-  the weight of the load tensions the fiber rope and the bend-
                                                              ing of the tensioned rope over the sheave can generate exces-
                                                              sive heat that damages the rope.
                                                               Rather than simply bearing the weight of a load with one
                                                              or more sheaves, the hoisting system 10 of figure 17 includes
                                                              a gripping assembly 32 for grabbing and holding the hoist-
                                                              ing line 20 to support the weight of the hoisted load. The
                                                              gripping assembly 32 is depicted in greater detail in figures
                                                              18 and 19 in accordance with one embodiment. The gripping
                                                              assembly 32 is shown here as including a chain 36 having
                                                              multiple links 40. As described further, the links 40 include
                                                              clamps for selectively closing about and gripping the hoisting
                                                              line 20, and the chain 36 can be driven to move the clamps of
                                                              the links 40 to raise or lower the hoisted load.
                                                               While only portions of the chain 36 are depicted in figure
                                                              18, the chain 36 is provided here as a closed loop positioned
                                                              about an upper sheave  42 and a lower sheave  44. A ten-
                                                              sioner 46 is provided to help maintain tension on the chain
                                                              36 during use. The tensioner 46 is shown here as a passive
                                                              hydraulic cylinder, but could take any other suitable form.
                                                              Motors 50 and gearboxes 52 drive the chain 36 in a closed
         Figure 17: Hoisting system in the form of a knuckle-jib crane having a   circuit about the sheaves 42 and 44. Any suitable motors 50
         gripping assembly for pulling a hoisting line.       could be used, such as electric motors or hydraulic motors. In
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