Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 36

lang lay
right
zZ

ordinary lay
right
sZ

left
sS

left
zS

Fig. 1.32 Lay directions of stranded ropes

the outer strands themselves. If both the wires in the outer strands and the outer
strands themselves have the same lay direction, the rope is called a lang lay rope
(formerly Albert's lay or Lang's lay), Fig. 1.32 . The strand lay direction normally
used is right (Z).
Figure 1.33 shows the cross-sections of various kinds of stranded ropes (with
fibre cores). The ropes most commonly used are single-layer stranded ropes.
Multi-strand ropes are all more or less resistant to rotation and have at least two
layers of strands laid helically around a centre. The direction of the outer strands is
opposite to that of the underlying strand layers. Ropes with three strand layers can
be nearly non-rotating. Ropes with two strand layers are mostly only low-rotating.
A proposal for the definition of the limits and characteristics of non-rotating ropes
is to be found in Sect. 2.4.2 .
Cable-laid ropes consist of several (usually six) round stranded ropes (referred
to as unit ropes) closed helically around a core (usually a seventh stranded rope).
Such a cable-laid rope is shown in Fig. 1.34 —in this case with fibre cores in the
stranded ropes as well as in the whole rope. Cable-laid ropes are only used as rope
slings.
Oval strand ropes are usually constructed with two oval strand layers as shown
in Fig. 1.35 . The direction of the outer strands is opposite to that of the underlying
strand layers. These ropes are rotation-resistant. Triangular strand ropes are often
only constructed with a single-layer as shown in Fig. 1.35 .