Wire Rope Ident i f icat ion and Construct ion
3
G E N E R A L
I N F
O R M A T I
O N
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
G E N E R A L
I N F O R M A T I O N
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
5
G E N E R A L
I N F
O R M A T I
O N
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