Wire Rope is a Machine

A wire rope is a machine, by dictionary definition: “An assemblage of parts…that transmit forces, motion, and energy one to another in some predetermined manner and to some desired end.”

A typical wire rope may contain hundreds of individual wires which are formed and fabricated to operate at close bearing tolerances one to another. When a wire rope bends, each of its many wires slides and adjusts in the bend to accommodate the difference in length between the inside and the outside bend. The sharper bend, the greater movement.

Every wire rope has three basic components:
(1) The wires which form the strands and collectively provide the rope strength;
(2) The strands, which are helically around the core; and,
(3) The core, which forms a foundation for the strands.

The core of wire rope may be an Independent Wire Rope Core (IWRC), which in many cases is actually a rope in itself. The IWRC in Python® rope provides between 10% and 50% (in non-rotating constructions) of the wire rope’s strength.

The greatest difference in wire ropes are found in the number of strands, the construction of strands, the size of the core, and the lay direction of the strand versus the core.

The wires of wire rope are made of high-carbon steel. These carbon steel wires come in various grades. The term “Grade” is used to designate the strength of the wire rope. Wire ropes are usually made of Extra Improved Plow Steel (EIPS) or Extra Extra Improved Plow Steel (EEIPS) [Approximate equivalents are 1960 N/mm² or 2160 N/mm² steel grades].

One cannot determine the Tensile Grade of a wire rope by its feel or appearance. To properly evaluate a rope’s tensile grade you must obtain the Grade from your employer or Unirope Limited @ 1.800.457.9997.