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Wire Rope Basics

Wire Rope Basics Blog Header

Wire Rope Basics

Wire rope is a versatile alternative to chain that is used in a variety of applications such as overhead lifting, rigging, lashing, towing, and construction. Wire rope can be found in elevators, bridges, cranes, aircraft, and anywhere a strong and dependable method of transferring mechanical force is required.

Wire rope is a complex mechanism with many interconnected parts that is frequently used in assemblies with wire rope hardware and other lifting and rigging equipment.

By no means comprehensive, this article serves as a surface level introduction to the basics of Wire Rope.

Anatomy of Wire Rope

Wire Rope consists of three components

  1. The CORE is the center of the wire rope.

The core serves as the foundation to hold the rope together. There are three types of cores:

  • Fiber – synthetic or sisal, which is the weakest
  • Strand – the core is a wire strand, just like the other strands of the rope
  • Independent Wire Rope (IWRC) – this is a separate wire rope. It is the strongest of the three types.
  1. The WIRE is the basic unit of the wire rope. The wires form the strand. Most wire is high carbon steel, but other material types are available.
  2. The STRAND is made up of a specific number of wires, laid helically around a wire core.


6x19 wire rope illustration

The most common type used in industry is 6 x 19. This is six strands comprised of approximately 19 wires

(#2 Figure 1) but may have 16 through 26 wires per strand. It has a good combination of flexibility and wear resistance.

Rope Lay

The term rope lay signifies the direction of rotation of the wires and the strand (#3 Figure 1). Rotation is either to the right (clockwise) or left (counterclockwise). The standard is right regular lay. Left-lay rope is for special-purpose applications. The lay-length is the distance measured along a rope in which a strand makes one complete revolution around the axis. Wire rope slings have great strength combined with flexibility. They do not wear as rapidly and the indication of broken wires and appearances show its true condition.

wire rope lays illustration

Regular lay is more stable and more resistant to crushing than lang lay, while lang lay is more fatigue resistant and abrasion resistant. For standard non-rotation-resistant ropes, lang lay use is normally limited to single layer spooling and when the rope and load are restrained from rotation.

wire rope protectors

Wire rope should be protected with softeners or blocking when used at corners or sharp bends. This is especially important when the load approaches the capacity of the rigging.

Fatigue Resistance

Fatigue resistance involves metal fatigue that make up a rope. To be fatigue resistant, wires must be capable of repeatedly bending under stress, such as when a rope passes over a sheave. The use of numerous wires in a rope design results in increased fatigue. It involves both basic *metallurgy and wire diameters. Smaller wires have a greater ability to bend as the rope passes over sheaves or around drums, so a rope made of many wires will have greater fatigue resistance than a rope made of fewer larger wires.

To avoid fatigue, ropes should never be bent over sheaves or drums with such a small diameter that they kink or bend wires excessively. There are specific recommendations for sheave and drum sizes to accommodate all rope sizes and types. Because every rope is subject to metal fatigue from bending stress while in use, the rope’s strength gradually decreases as the rope is used.

Click here to read our ‘Avoid Common Wire Rope Damage’ Blog.


The strength of wire rope is typically measured in tonnes of 2,000 pounds. Engineers assign the rope a nominal strength called “Breaking Strength” in the catalogue. When tensioned on a test device, new ropes will break at a figure equal to or greater than the catalogue figure. The catalogue price is for new, unused rope. A rope should never be used at its full catalogue strength.

A rope gradually loses strength over its useful life due to natural causes such as surface wear and metal fatigue. As a result, a Factor of Safety is used during rope selection in order to build service life into a rope installation.

With each application, your choices of wire ropes can be many. How do you know which one works best for you? Ropes include a combination of properties that give them specific performance abili¬ties. Before you choose, it pays to look closely at each rope’s special properties.

No Single Wire Rope Can Do It All

All wire ropes feature design property trade-offs. In most cases, a wire rope cannot increase both fatigue resistance and abrasion resistance. For example, when you increase fatigue resistance by selecting a rope with more wires, the rope will have less abrasion resistance because of its greater number of smaller outer wires. When you need wire rope with greater abrasion resistance, one choice is a rope with fewer (and larger) outer wires to reduce the effects of surface wear. But that means the rope’s fatigue resistance will decrease.
That’s why you need to choose your wire rope like you would any other machine. Very carefully.

wire rope in the sheave groove for lifting equipment

You must consider all operating conditions and rope properties.

At Hercules SLR, we know the ropes! Our experts can help and advise you when it comes to choosing the right wire rope for your specific project. Find your nearest branch here


*Metallurgy is the art, science, and technology of turning metals and alloys (i.e., materials consisting of two or more metals) into forms suitable for practical use.