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         54b of each link member 54 when angle Σ approaches 90°. In
         this arrangement, the restriction of angle Σ to less than 90°
         via stop member 64 prevents links 54 from binding during
         the actuation of portable net barrier 10.
           Each  link  member  54  includes  a radial opening  58  dis-
         posed proximal first end 54a that extends radially into the
         generally tubular outer surface of each link 54, and an axial
         opening 60 disposed at first end 54a of each link 54 distal
         hinged joint 62. Openings 58 and 60 are configured to allow
         for  the  passage of  one  of  the  cables  30  through  each  link
         member 54. Specifically, cables 30 extend between the pair
         of buttress assemblies 50, enter link members 54 via radial
         openings  58, exit link  members  54 via axial openings  60
         at first end 54a, and extend to and couple with anchoring   Figure 4: Side perspective and elevational view of a first embodiment
         assembly 90. Thus, the passage of cables 30 through link   cable guide.
         members 54 via openings 58 and 60 form the coupling be-
         tween cables 30 and link assembly 52. Each link member 54   for example as defined by a central shaft joining together the
         further includes an annular retaining member 63 disposed   two arms through a central hole in the sheave, the sheave
         at the axial opening 60 at first end 54a and having a central   is fixed in place so as to be non-rotatable about its axis. A
         bore 63a for the passage of cable 30. Retaining member 63   sheave liner or insert 14 of suitable wear material, for exam-
         is configured to restrict relative movement between cable 30   ple nylon or another polymeric material, lines the peripheral
         and link member 54 (particularly relative movement along   groove of the sheave, and presents a concave channel that
         the axial length of link members 54). Particularly, retaining   opens circumferentially  outward from the sheeve around
         member 63 restricts cable 30 from being displaced through   the full periphery thereof. The nylon or other material of the
         openings  58 and  60, thereby restraining  the position of   insert provides a coefficient of friction at the outwardly fac-
         cable 30 with respect to link member 54. However, retain-  ing concave surface of the liner that exceeds that provided
         ing members 63 do not permanently affix cables 30 to link   by the material of the sheave itself at its peripheral groove
         assembly 52. Instead, a sufficiently strong force applied to   lying under the liner or insert. The sheave and bracket are
         cables 30 will allow each cable 30 to decouple from, and be   made of metal or other material that is of greater strength
         displaced relative, link members 54.                 and hardness than the liner, and provides a rigidly shaped
           For instance, when portable net barrier 10 is in the closed   pathway for the drilling line to follow, unlike the prior art
         position and is impacted by a moving vehicle attempting to   use of a flexible sling.
         traverse between buttress assemblies 50, a reactive tension
         force from the collision is applied to cables 30 from net 20 suf-
         ficient to overcome the restraining force provided by the phys-
         ical engagement between retaining members 63 and cables
         30, thereby allowing cables 30 to be displaced through radial
         openings 58. Thus, retaining members 63 are configured to
         couple or cables 30 to link assembly 52 during normal opera-
         tion, such as actuation between the closed and open positions
         illustrated in figures 1 and 2, but upon impact between a mov-
         ing vehicle and the net 20, members 63 are configured to al-
         low cables 30 to decouple from link assembly 52, such that
         they may be displaced through openings 58 and 60.

         Replaceably lined cable guides and tensioning roller
         for drill line slip and cut operations on a drilling rig  Figure 5: Exploded perspective view of a second embodiment cable guide.
         Pat. 9,702,208 U.S. class E21B 19/24 Int. class B66D 1/36
         Inventor: Jesse Urquhart, Edmonton, CA.               Accordingly, with the drill line of the drilling rig routed
         Assignee: Jesse Urquhart, Edmonton, CA.              over the sheave, which is hung on the coupler 100 at the
           The patent presents cable guides for overhead support of   lower end of the air tugger line 102 by hooking of the coupler
         drill line on a drilling rig during a slip and cut operation   100 through the apex 12a of the cable guide’s support brack-
         featuring replaceable liners of wear material supported by a   et 12, resistance to the movement of the drill line over the
         re-usable base. A tensioning roller added to the draw-works   sheave is increased compared to the resistance that would
         resides outward from the periphery of the draw-works drum   be experienced without use of the liner. The cable guide thus
         and is spring-biased toward same into order to force the in-  provides a notable degree of frictional grip to the drill line to
         coming drill line against the periphery of the drum.  prevent inadvertent pulling or slipping of the drill line from
           Figure 4 shows a first embodiment cable guide that is used   the  cable guide,  while  its  two-piece  construction  ensures
         directly in place of the prior art sling. The cable guide some-  that even if the wearable liner was to wear fully through,
         what resembles a conventional pulley in the form of sheave   the sheave remains intact to still carry the apex of the slack
         10 mounted in a support bracket  12. The bracket  12 has   portion of the drill line routed through the bracket lets and
         a pair of arms at opposite faces of the sheave that extend   over the sheave. Personnel can thus monitor the status of
         radially of the sheave and join together at an apex 12a lo-  the liner, or schedule routine replacement thereof at inter-
         cated circumferentially outward from the sheave. However,   vals known to be less than the effective lifespan of a liner in
         instead of the sheave being rotatable about its central axis,   relation to the usage of the drill line, for example as typically

         58     Wire Rope News & Sling Technology   October 2017
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