Wire rope fittings enable the connection and manipulation of structural wire rope to various substrates or platforms. They are essential as wire rope cannot be trivially connected to equipment given it cannot be (conventionally) knotted and splicing is generally not an option for most users.
There are many different types, sizes, styles, and finishes of wire rope fittings which are suitable for most types of wire rope. These Wire Rope Fittings group into three general application classes of fittings which are Terminators, Connectors, and Adjusters. While these classes are useful in understanding the application of fittings, The classes are NOT exclusive.
There are a number of fittings that can actually cover all three classes. And these classes of fittings exist in the different categories of fittings which are Marine, Commercial, and Rated. The classes are explained and some of the more common groups of wire rope fittings are detailed below.
- Terminators (terminals) secure the ends of wire rope, often forming loops or fasteners on the ends of a wire that enable secure attachment.
- Connectors are attached to Terminators to form an anchor point which allows terminated wire to be attached to a substrate.
- Adjusters are attached to Terminators and/or Connectors and offer a means of dynamically shortening (Pulling/Tension Applications) or lengthening (Pushing/Compression Applications) or tightening (Holding/Static Applications)
Thimbles: A wire rope thimble is used in wire rope hard eye terminations to prevent the wire rope eye from being crushed and reducing wear on the rope itself. When a wire rope is terminated with an eye at the end, it is called a “Soft Eye” if the thimble is not included. If a thimble is included to form the eye of the loop before the rope is secured in the ferrule or wire rope grip, then it is a “Hard Eye”
Clips / Grips: A wire rope grip or bulldog clip is used to clamp the ends of a wire rope after it has been looped back to form an eye – of any sort. It is strongly recommended that wire rope terminal eyes utilize a minimum of three wire rope grips, depending on the wire and application to properly secure the ends.
Sleeves / Ferrules: Wire rope ferrules are also used to “clamp” wire rope ends using either a crimping process (hourglass ferrules) or a swaging process (oval ferrules). Properly applied oval shaped sleeves are uniformly crushed around the wire rope to form either sort of eye, an end stopper, or a lap splice on the wire rope assembly. This can be done either by hand tools (normally crimping) or via a hydraulic press (normally swaging). Manual pressing of any sort of ferrule is only recommended on smaller diameters of wire ropes.
Turnbuckles/Rigging screws: These for the key types of wire rope Adjuster fittings that are attached to wire rope terminations and are then used to adjust the effective length of wire rope. Turnbuckles can have an open or closed frame and typically consist of two threaded ends (one a RHT form and one a LHT form of a threaded connection such as a eye bolt, hook bolt, swaging bolt, threaded rod, etc), one at each end of a metal frame. The RHT and LHT allows the effective length of the wire rope can then be adjusted by rotating the frame.
Terminals: A wire rope terminal is a Terminator fitting that is permanently attached using a hydraulic press to the end of the wire rope using the swaging process. These come in a variety of forms and can be used instead of thimbles, wire rope grips or ferrules to achieve a termination. Please note that swaging – compared to crimping 0is a much more technical process. Swaging requires specialized tools and knowledge to adequately fit these types of fittings to wire rope in a way that achieves a connection that has reliable and predictable strength.
Links / Rings / Hooks: A terminated wire rope needs to be fastened to an anchor point for its structural capabilities to be achieved. This connector application class of fitting delivers on this requirement. This class of fittings is extremely dimensionally diverse and often highly specialized or single duty in their design. They may be round, flat, threaded, or twisted – but they exist primarily to fasten a terminated wire assembly to a substrate by forming an anchor point.