They are made of thin wires with diameter of 0,22-3 mm, which are twisted into strands, and strands – into rope. Ropes produced by industry come in single, double or triple strand designs. In a single-strand rope is formed from individual wires, with double strand – wires pre-rolled in strands, and strands – in the rope, called the rope, with a triple – the rope is made of several strands of double strand and is called a cable.
The following kinds of wire ropes are commonly used for installation and rigging work, as well as in lifting equipment:
cross strand, when the wire in each strand is twisted to one side and the strands – to the other side;
single-sided strand, when wires and strands are stranded in one direction;
Combined strand, when a part of the strands is in a straight line and the other part is in a cross-twist.
Nowadays, ropes of the compound type are also used, twisted from strands consisting of wires of different diameters. These ropes are more durable and wear resistant.
For installation works, ropes of six strands with the number of wires in a strand 19, 37 and 61, arranged around a hemp core are used most often. Soft cores give ropes flexibility, elasticity, and absorb grease to protect the wires from rust.
Depending on the application, ropes with 19 and 37 strand counts per strand are recommended for hoisting machines, 19 for slings and 37 and 61 for slings.
Galvanized and light wire is used for rope production. The mechanical strength of galvanized wire ropes is 7-10% lower, but they are more resistant to corrosion. Wires are made of steel with specified tensile strength of 120 – 260 kgmm2.
