Figure 5-4.Lays of wire rope.
strand. Lay length measurement is shown in
CLASSIFICATION OF WIRE ROPE
The primary types of wire rope used by the NCF
consist of 6, 7, 12, 19, 24, or 37 wires in each strand.
Usually, the wire rope has six strands laid around the
The two most common types of wire rope, 6 by 19
and 6 by 37, are shown in figure 5-6. The 6 by 19 type
(having six strands with 19 wires in each strand) is the
stiffest and strongest construction of the type of wire
rope suitable for general hoisting operations. The 6 b y
37 wire rope (having six strands with 37 wires in each
strand) is flexible, making it suitable for cranes and
similar equipment where sheaves are smaller than
Figure 5-5.Lay length of wire rope.
Figure 5-6.A. 6 by 19 wire rope; B. 6 by 37 wire rope.
usual. The wires in the 6 by 37 are smaller than the
wires in the 6 by 19 wire rope and, consequently, will
not stand as much abrasive wear.
WIRE ROPE SELECTION
Several factors must be considered when you
select a wire rope for use in a particular type of
operation. Manufacture of a wire rope that can
withstand all of the different types of wear and stress,
it is subjected to, is impossible. Because of this factor,
selecting a rope is often a matter of compromise. You
must sacrifice one quality to have some other more
urgently needed characteristic.
Tensile strength is the strength necessary to
withstand a certain maximum load applied to the rope.
It includes a reserve of strength measured in a
so-called factor of safety.