An Introduction to Wire Rope and Wire Rope Hardware

Wire rope is a versatile alternative to chain used in many applications, including overhead lifting, rigging, lashing, towing, construction, and more. You will find wire rope in elevators, bridges, cranes, aircraft, and everywhere a robust and reliable method of transferring mechanical force is needed.

Wire rope is a complex mechanism composed of many interacting parts, and it’s often used in assemblies with wire rope hardware and other
lifting and rigging equipment. In this article, we will explore what wire rope is and how wire rope hardware is used to join ropes and create attachment points. We’ll also look at how to use wire rope and related hardware safely.

Wire rope is a rope constructed of metal wire strands braided together around a core. Modern wire ropes are made from four primary components:

The rope’s material and construction affect its properties and suitability for tasks such as lifting, hoisting, and towing. Among the factors that should be considered when selecting wire rope are:

Tensile strength, also known as minimum breaking strength, is the most important factor in most rigging scenarios, as we discuss in the next section.

Wire rope is rated with a minimum breaking strength verified through testing by the manufacturer. However, wire rope should not be exposed to loads approaching the minimum breaking strength. Instead, the user should take the minimum breaking strength and a design factor into account when determining the Working Load Limit (WLL). A wire rope should never be used with loads that exceed the WLL.

The design factor represents the ratio of the breaking strength to the load the rope is expected to carry. The most frequently used design factor for wire rope is 5, which indicates the maximum operating load must be less than 20% of the minimum breaking strength. However, design factors may be considerably higher than 5, particularly in use‑cases with risk of danger to people or property. Minimum design factors are described in
OSHA 1926.1414 – Wire Rope Selection and Installation Criteria and additional regulations with information related to wire rope design factors can be found in
ASME B30.9-2018.

If the design factor is 5, the calculation for determining the WLL is:

WLL = minimum breaking strength / 5

In addition to selecting a wire rope with an appropriate WLL, users should follow these basic safety precautions:

• Before use, inspect wire ropes for damage such as kinks, broken wires and strands, reduction in the wire’s diameter, excessive abrasion, crushing, or stretching. Damaged wire rope should immediately be withdrawn from use.
• Inspect any wire rope hardware for damage.
• Do not expose wire ropes to shock loads through rapid changes in direction or dropping. Shock loads may exceed the WLL and damage the rope and other hardware.

The United States Department of Labor’s Occupational Safety and Health Administration (OSHA) provides a set of inspection rules that wire rope users should adhere to
OSHA Regulation 1926.1413 explains when ropes should be inspected and the deficiencies that indicate a rope should be removed from service. For example, a wire rope is considered deficient if it exhibits “six randomly distributed broken wires in one rope lay or three broken wires in one strand in one rope lay.”

Other relevant OSHA regulations include:

• 1919.24 — Limitations on Use of Wire Rope
• 1910.184 and 1910.251 — Slings

Wire Rope Hardware

Wire rope hardware is used to terminate wire ropes, splice rope lengths together, and form an attachment point for connecting wire rope to other rigging equipment. Note that the wire rope hardware discussed here is not suitable for overhead lifting.

To understand how wire rope hardware works, you should be familiar with the following terms.

• Wire rope eye
  — a loop formed at the end of the rope to attach other rigging hardware.
• Lap splice
  — a splice that joins two ropes together by overlapping their ends and connecting them with wire rope clips or sleeves.
• Live end
  — when attaching two ropes or folding rope back on itself to form an eye, the live end is the weight‑bearing section of the rope.
• Dead end
  — the non‑weight‑bearing section. For example, the shorter end of a rope that has been folded back to form an eye.
• Turnback
  — the length of wire rope from the base of an eye to the end of the dead end.

Wire Rope Thimbles

A
wire rope thimble is a tear‑drop‑shaped metal fitting placed within a wire rope eye. The thimble helps maintain the loop’s shape and prevents crushing, fraying, or pinching with the loop is used to attach the rope to other rigging hardware. Thimbles are often used in concert with wire rope sleeves and single- or
double‑saddle clips to create strong, durable loops.

Wire Rope Sleeves

Wire rope
sleeves are clamp fittings used to form loops or to connect wire ropes. They are also known as ferrules, cable crimps, crimp sleeves, or swage sleeves. Wire rope sleeves are made of stainless steel or aluminum and are available in sizes to suit ropes of varying dimensions.

Wire rope sleeves are fixed to the rope by swaging, also known as crimping. Swaging is the process of compressing the sleeve so it deforms to grip the rope. To form a loop using a wire rope sleeve, the live and dead ends are inserted into one or more sleeves, which are then crimped using a swage tool, which may be a hand tool or a larger hydraulic machine.

The correct number of crimps is determined by the size of the wire rope sleeve. The bigger the sleeve, the more crimps it requires.

The order in which the crimps are applied to the wire rope sleeve is also important to maximizing performance. For example, in a sleeve requiring three crimps, the first should be in the center, the second towards the eye, and the third at the opposite end.

Wire Rope Clips

Wire rope clips, also known as U‑bolt cable clips or single‑saddle rope clips, feature a saddle, a U‑shaped bolt, and a pair of nuts. Wire rope clips are an easy‑to‑install and remove alternative to wire rope sleeves, which are permanent. They are used to splice ropes or form eye loops. Both segments of the rope are passed through the bolt and the nuts are tightened to the manufacturer’s specified torque.

A U‑bolt clamp should be used with the saddle positioned against the live end while the U‑bolt contacts the dead end. At least two rope clips are required to create a secure attachment.

Fist grip clips perform a similar role to U‑bolt clips, but they feature two saddles instead of a saddle and U‑bolt, which is why they are also known as double‑saddle wire rope clips. Fist grip clips have several advantages over U‑bolt clips, including:

• Fist grip clips are simpler to install because the two saddles make it impossible to incorrectly position the live end and the dead end of the tope.
• Fewer fist grip clips are needed for lap splices.

As with U‑bolt clips, the bolts on fist grip clips should be tightened to the manufacturer’s recommended torque using a torque wrench. They should be re‑torqued after an initial test load.

When selecting wire rope clips, including fist grip clips, the clip size should match the diameter of the wire rope. If the clip is too large or small, the rope will not be held securely and the strength of the assembly is significantly reduced. ASME B30.26 requires the clip size to be displayed on the body of all wire rope clips. Huyett customers can filter our
online catalog by clip size to find the right hardware for their use case.

We have already looked at the safe use of wire rope, but there are many other issues to consider when using wire rope hardware, such as clips and sleeves. If wire rope hardware is improperly used, the strength of a rope assembly may be significantly reduced. When selecting and installing wire rope hardware, it is vital that you follow the manufacturer’s instructions and rigging best practices.

• Always apply the recommended torque to nuts on U‑bolt clips and fist grip clips. Under‑torquing can result in reduced holding power, and over‑torquing can damage the hardware or the wire rope.
• Clips should be re‑torqued to the recommended torque specifications after loading.
• Wire rope hardware must be correctly sized to match the diameter of the wire rope it is used with.
• Wire rope clips must be used in the quantity recommended by the manufacturer.
• When forming a loop or connecting wire rope, ensure there is sufficient length on the dead end to accommodate the correct number of clips.
• Inspect wire rope hardware regularly for damage, deformation, or corrosion.
• Always use a wire rope thimble when forming an eye at the end of a wire rope.

Huyett stocks a comprehensive selection of wire rope hardware, including
wire rope sleeves,
U‑bolt clips,
fist grip clips,
wire rope thimbles, and
welded rings. To learn more, visit
Wire Rope Hardware & Clips or
contact our Sales Team.