When they are not shaped before fabrication, the wire
rope is termed nonpreformed wire rope.
The most common type of manufactured wire rope
is preformed. When wire rope is cut, it tends not to
unlay and is more flexible than nonpreformed wire
rope. With nonpreformed wire rope, twisting produces
a stress in the wires; therefore, when it is cut or broken,
the stress causes the strands to unlay.
When wire rope is cut or broken, the almost
instantaneous unlaying of the wires and strands
of nonpreformed wire rope can cause serious
injury to someone that is careless or not familiar
with this characteristic of the rope.
GRADES OF WIRE ROPE
The three primary grades of wire rope are mild
plow steel, plow steel, and improved plow steel.
Mild Plow Steel Wire Rope
Mild plow steel wire rope is tough and pliable. It
can stand repeated strain and stress and has a tensile
strength (resistance to lengthwise stress) of from
200,000 to 220,000 pounds per square inch (psi).
These characteristics make it desirable for cable tool
drilling and other purposes where abrasion is
Plow Steel Wire Rope
Plow steel wire rope is unusually tough and
strong. This steel has a tensile strength of 220,000 to
240,000 psi. Plow steel wire rope is suitable for
hauling, hoisting, and logging.
Improved Plow Steel Wire Rope
Improved plow steel wire rope is one of the best
grades of rope available and is the most common rope
used in the Naval Construction Force (NCF).
Improved plow steel is stronger, tougher, and more
resistant to wear than either mild plow steel or plow
steel. Each square inch of improved plow steel can
stand a strain of 240,000 to 260,000 pounds; therefore,
this wire rope is especially useful for heavy-duty
service, such as cranes with excavating and
LAYS OF WIRE ROPE
The term lay refers to the direction of the twist of
the wires in a strand and the direction that the strands
are laid in the rope. In some instances, both the wires
in the strand and the strands in the rope are laid in the
same direction; and in other instances, the wires are
laid in one direction and the strands are laid in the
opposite direction, depending on the intended use of
the rope. Most manufacturers specify the types and
lays of wire rope to be used on their piece of
equipment. Be sure and consult the operators manual
for proper application.
The five types of lays used in wire rope are as
Right Regular Lay: In right regular lay rope, the
wires in the strands are laid to the left, while the strands
are laid to the right to form the wire rope.
Left Regular Lay: In left regular lay rope, the
wires in the strands are laid to the right, while the strands
are laid to the left to form the wire rope. In this lay, each
step of fabrication is exactly opposite from the right
Right Lang Lay: In right lang lay rope, the
wires in the strands and the strands in the rope are laid
in the same direction; in this instance, the lay is to the
Left Lang Lay:
In left lang lay rope, the
wires in the strands and the strands in the rope are
also laid in the same direction; in this instance, the
lay is to the left (rather than to the right as in the
right lang lay).
Reverse Lay: In reverse lay rope, the wires in
one strand are laid to the right, the wires in the nearby
strand are laid to the left, the wires in the next strand are
laid to the right, and so forth, with alternate directions
from one strand to the other. Then all strands are laid to
The five different lays of wire rope are shown in
LAY LENGTH OF WIRE ROPE
The length of a wire rope lay is the distance
measured parallel to the center line of a wire rope in
that a strand makes one complete spiral or turn around
the rope. The length of a strand lay is the distance
measured parallel to the centerline of the strand in that
one wire makes one complete spiral or turnaround the