Wire Rope Ident i f icat ion and Construct ion

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Wire ropes are identified by a nomenclature that is referenced to: 1) the number of strands in the rope, 2) the number

(nominal or exact) and arrangement of wires in each strand, and 3) a descriptive word or letter indicating the type of

construction, i.e., the geometric arrangement of wires.

Figure 1. Four Basic Strand Patterns

Figure 2. Combination Strand Patterns

(1 ) STRAND CENTER

The strand center is usually confined to use in stationary

ropes such as guys, suspension bridge cables, and in

ropes of small diameter such as aircraft cable. It is also

occasionally specified on installations where severe

crushing may be experienced.

(2 ) FIBER CENTER

This center is made of either pre-lubricated Java sisal

fibers or plastic fibers, usually polypropylene. These

fibers are made into an extremely hard-laid rope which

will stand up under the high pressures of rope service.

These centers are used only when normal operating

loads do not rupture the fibers. The polypropylene center

is generally recommended when operating conditions

other than crushing destroy the sisal. One example

would be the presence of acid.

(3 ) INDEPENDENT WIRE ROPE

CENTER ( IWRC)

 An independent wire rope center is usually specified to

provide for one or more of three particular requirements,

as follows:

(a) Increased strength

(b) Greater resistance to crushing

(c) Resistance to excessive heat

 An “IWRC” increases the strength by 7% and weight of

a wire rope by 10%, and decreases the flexibility

slightly. It greatly increases the resistance of the wire

rope to crushing and is especially recommended on

installations where severe loads are placed on ropes

running over sheaves or wound on drums. Unless

required for one or more of the above properties, the

use of an “IWRC” should be avoided.

7 WIRE 19 WARRINGTON 19 SEALE 25 FILLER WIRE

31 WARRINGTON 46 SEALE

FILLER WIRE

43 FILLER

WIRE SEALE

49 SEALE

WARRINGTON SEALE

SELECTING THE PROPER TYPE OF WIRE ROPE CENTER

There are three general types of wire rope centers.

 

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Wire Rope Ident i f icat ion and Construct ion

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WIRE ROPE CROSS SECTIONS

Cross sections of some commonly used wire rope constructions.

6 x 7 FIBER CORE 6 x 19 SEALE

IWRC

6 x 21 FILLER WIRE

WITH FIBER CORE

6 x 25 FILLER WIRE

WITH FIBER CORE

6 x 25 FILLER WIRE

IWRC

6 x 26 WARRINGTON

SEALE IWRC

6 x 19 STAINLESS STEEL 7 x 7 AIRCRAFT CABLE 7 x 19 A IRCRAFT CABLE 7 x 7 x 19 CABLE LAID

6 x 31 WARRINGTON

SEALE IWRC

6 x 36 SEALE FILLER

WIRE IWRC

6 x 36 WARRINGTON

SEALE FIBER CORE

6 x 31 FILLER WIRE

SEALE IWRC

6 x 36 SEALE

IWRC

6 x 41 WARRINGTON

SEALE IWRC

19 x 7 NON-

ROTATING

35 x 7 ROTATION-

RESISTANT

19 x 19 ROTATION-

RESISTANT8 x 25 ROTATION-

RESISTANT

 

Wire Rope Ident i f icat ion and Construct ion

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CONSTRUCTION OF TYPICAL ROPE LAYS

Five different lays of rope to choose from.

Wire rope is identified not only by its component parts, but also by its construction, i.e., by the way the wires have been

laid to form strands, and by the way the strands have been laid around the core.

 A regular lay rope is one in which the direction of lay of the wires of the individual strands is opposite to that of the

strands in the rope resulting in the individual wires running parallel to the longitudinal axis of the rope.

 A lang lay rope is one in which the direction of the wires of the individual strand is the same as that of the strands in the

rope resulting in the individual wires running diagonally across the longitudinal axis of the rope.

In an alternate right and left lay rope, the strands are alternately regular lay and lang lay. This construction is seldom

used, its principal application being on button conveyors.

Lang lay ropes are advantageous over regular lay ropes in that they provide a greater wearing surface, result in less

wear on sheave equipment and provide a greater bending fatigue resistance, however, they are not nearly as stable as

regular lay ropes from a standpoint of resisting crushing and “bird-caging,” therefore they are limited in their applications

and should be used only where recommended by a qualified wire rope engineer.

(1) Right Regular Lay

(2) Left Regular Lay

(3) Right Lang Lay

(4) Left Lang Lay

(5) Right Alternate Lay

Wire Rope Technical Board