SECTOR FOCUS: INDUSTRIAL LUBRICATION
Lubrication Basics for Wire Ropes
Jeffrey E. Turner, Lubrication Engineers, Inc.
Wire rope forms an important part of many machines and structures. It is comprised of continuous wire strands wound around a central core. There are many kinds of wire rope designed for different applications. Most of them are steel wires made into strands wound with each other. The core can be made of steel, rope or even plastics.
Wire ropes (cables) are identified by several parameters including size, grade of steel used, whether or not it is preformed, by its lay, the number of strands and the number of wires in each strand.
A typical strand and wire designation is 6x19. This denotes a rope made up of six strands with 19 wires in each strand. Different strand sizes and arrangements allow for varying degrees of rope flexibility and resistance to crushing and abrasion. Small wires are better suited to being bent sharply over small sheaves (pulleys). Large outer wires are preferred when the cable will be rubbed or dragged through abrasives.
There are three types of cores. An independent wire rope core (IWRC) is normally a 6x7 wire rope with a 1x7 wire strand core resulting in a 7x7 wire rope. IWRCs have a higher tensile and bending breaking strength than a fibre core rope and a high resistance to crushing and deformation.
A wire strand core (WSC) rope has a single wire strand as its core instead of a multistrand wire rope core. WSC ropes are high strength and are used mostly as static or standing ropes.
Wire ropes also have fibre cores. Fibre core ropes were traditionally made with sisal rope, but may also be made with plastic materials. The fibre core ropes have less strength than steel core ropes. Fibre core ropes are quite flexible and are used in many overhead crane applications.
Figure 1: Comparison of Typical Wire Rope Lays: a) Right Regular, b) Left Regular, c) Right Lang, d) Left Lang, e) Right Alternate
The lay of a wire rope is the direction that the wire strands and the strands in the cable twist. There are four common lays: right lay, left lay, regular lay and lang lay. In a right lay rope, the strands twist to the right as it winds away from the observer. A left lay rope twists to the left. A regular lay rope has the wires in the strands twisted in the opposite direction from the strands of the cable. In a lang lay rope, the twist of the strands and the wires in the strands are both
10 LUBE MAGAZINE NO.152 AUGUST 2019
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
