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01 - WIRE ROPE & STRAND

1300 722 999

8

Characteristics of Lay

RIGHT HAND ORDINARY LAY

RIGHT HAND LANG’S LAY

LEFT HAND LANG’S LAY

LEFT HAND ORDINARY LAY

ONE ROPE LAY

The direction of rope Lay does not affect the breaking force of

a rope. However, the combination of strand lay and rope lay will

greatly affect the rope characteristics and this factor must be

taken into consideration when choosing a rope. Although the lay

length can slightly affect rope behaviour the dominant aspect

that influences performance is the direction of lay and whether

it is Lang’s Lay or Ordinary Lay. For example, the importance

of rope lay is evident in a four-part high lift grab where rotation

of the grab is prevented by the use of alternate right-hand and

left-hand ropes.

Lubrication

When a rope is operated over a drum or sheave, the strands

and wires move relative to one another. To reduce the resultant

friction within the rope as well as the friction between the rope

and drum or sheave, ropes are lubricated in manufacture.

In addition this lubrication also retards corrosion and inhibits

possible rotting of the fibre core. In special applications a

combination of lubricants may be required for example, the

core and inner wires of the strands may be heavily lubricated

while the lighter lubrication may be applied to outer wires and

strands.

Wire rope cores are normally heavily lubricated irrespective

of the outer strand lubrication. Regular lubrication is more

beneficial than applying large amounts infrequently.

Quality Control

Standard Specifications

All ropes are produced to comply with the requirements of the

Australian Standards. These specifications require wire to be

produced to AS1394. All ropes comply to AS3569 Steel Wire

Ropes.

The company’s testing facilities are constantly engaged on

the testing of both works production and samples received for

examination.

For investigation and customer service purposes, a non-

destructive testing unit, operated by Bullivants trained staff is

available. Enquiries concerning use of this equipment or advice

on non-destructive testing please contact your local Bullivants

branch. A full report of all site examination is issued.

Steel Quality - Tensile Strength

Production methods, equipment and quality control in

steelmaking and wire drawing ensure that wire rope conforms

to Australian and International Standards.

Wire ropes are usually supplied in the following tensile

ranges:

Minimum Tensile Abbreviated

Description

Black (bright,

ungalvanised) wire

1770 MPa

B1770 grade

Galvanised wire

1570 MPa

G1570 grade

NOTE: G1770 (Galvanised 1770 Mpa) is the preferred grade

for galvanised ropes other than standard multiple operation

ropes of 6 x 7, 6 x 19, 6 x 24 and 6 x 36 Construction.

However, other special tensile ranges can be supplied in

both galvanised and black as follows: 1220 MPa, 1420 MPa,

1970 MPa, 2070 MPa and 2250 MPa.

With the increasing use of heavy-duty and more compact

equipment (e.g. power winches on mobile cranes and mine

winding) there is a gradual upward trend in the required rope

wire tensile range. However, as factors other than strength

influence the life of wire rope, the specification application must

be kept in mind when the tensile strength of the wire is selected.

Care and Maintenance

Breaking In

A wire rope may be looked upon as a machine composed of

a large number of moving parts. As such it should be broken

in as soon as it is installed, by loading it very lightly for a few

cycles and then gradually stepping up the load, to enable both

wires and strands to ‘bed down’ into the working positions,

with the load distributed as uniformly as possible.

The use of ‘spinners’ or swivels should be avoided whenever

possible. All ropes should be reeled onto winch drums as tightly

and uniformly as possible during the initial installation.

Lubrication

Lubrication impregnated into the rope during manufacture is not

sufficient to last the life of the rope. Additional lubrication should

be done during the service.

The frequency of lubrication in the field is determined by the

operating conditions of the rope e.g., high-speed heavy duty

operation calls for more frequent lubrication, as do wet and/or

corrosive conditions.

For general purpose applications medium viscosity black oil is

considered suitable. For corrosive conditions a high penetrating,

water repellent rush-inhibiting oil should be used.

Inspection

Wire rope is tough and durable, but nonetheless expendable

and eventually reaches the end of its safe service life.

Rope deterioration becomes noticeable through the

presence of broken wires, surface wear, corrosion, wire or

strand distortion due to mechanical abuse, or drastic reduction

in diameter and lengthening of the lay. Also deterioration can be

detected by the use of non-destructive testing techniques. Wire

ropes should periodically be inspected for signs of deterioration.

Wire Rope Terms

Minimum Breaking Force (MBF)

MBF is the minimum load or force, guaranteed by the

manufacturer after which the rope will break. It is based on the

use of wires of nominal size and the minimum tensile strength.

This is the figure which should be used for design of rope

equipment.

Diameter

The measurement across the centre line of the circle

circumscribing the outer wires of a strand or the outer

strands of a rope.

Design Factor

Term applied to the required ratios of rope breaking force to

total rope force due to load. Normally set by Statutory bodies,

e.g. Mines Departments, Navigation Departments, Lifts and

Scaffolding Departments.