SEALE is where larger diameter wires are used
on the outside of the strand to resist abrasion and
smaller wires inside to provide flexibility.
WARRINGTON is where alternate wires are
large and small to combine great flexibility with
resistance to abrasion.
FILLER is where very small wires fill in the
valleys between the outer and inner rows of
wires to provide good abrasion and fatigue
CORE.The wire rope core supports the
strands laid around it. The three types of wire rope
cores are fiber, wire strand, and independent wire
rope (fig. 6-35).
A fiber core may be a hard fiber, such as manila
hemp, plastic, paper, or sisal. The fiber core
offers the advantage of increased flexibility. It
also serves as a cushion to reduce the effects of
sudden strain and acts as an oil reservoir to
lubricate the wire and strands (to reduce
friction). Wire rope with a fiber core is used
when flexibility of the rope is important.
A wire strand core resists more heat than a fiber
core and also adds about 15 percent to the
strength of the rope; however, the wire strand
core make the wire less flexible than a fiber core.
An independent wire rope core is a separate wire
rope over which the main strands of the rope are
laid. This core strengthens the rope, provides
support against crushing, and supplies
maximum resistance to heat.
Grades of Wire Rope
The three primary grades of wire rope are as
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)
from 200,000 to 220,000 pounds per square inch
Figure 6-35.Core construction.
(psi). These characteristics make it desirable for
cable tool drilling and other purposes where
abrasion is encountered.
Plow steel wire rope is usually 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 is one of the best
grades of rope available and is the most common
rope used in the NCF. This type of rope is
stronger, tougher, and more resistant to wear
than the others. Each square inch of improved
plow steel can stand a strain of 240,000 to
260,000 psi. This makes it especially useful for
heavy-duty service, such as on cranes with
excavating and weight-handling equipment.
Lays of Wire Rope
The term lay refers to the direction of the twist of
the wires in a strand and to 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 operator's manual
for proper application.
The five different lays used in wire rope are as
follows (fig. 6-36):
RIGHT REGULAR LAY has the wires in the
strands laid to the left, while the strands are laid
to the right to form the wire rope.
LEFT REGULAR LAY has the wires in the
strands 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 regular lay.
RIGHT LANG LAY has the wires in the strands
and the strands in the rope laid to the right.
LEFT LANG LAY has the wire in the strands
and the strands in the rope laid to the left.
REVERSE LAY has the wires in one strand laid
to the right, the wire in the nearby strand are laid
to the left, the wire in the next strand are to the
right, and so forth, alternating direction from one
strand to the other. Then all strands are laid to the