Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 38

Fig. 1.35 Oval strand rope
and triangular strand rope
Fig. 1.36 Special rope types
a Braided rope. b Flat rope
Special rope types. Braided ropes consist of several round strands that are inter-
laced or plaited together, Fig. 1.36 a. The lay direction for one half of the strands is
right and for the others left. This means that braided ropes really are non-rotating.
However, when braided ropes are bent over sheaves they do not last very long and
so these ropes are only used in exceptional cases.
Flat ropes consist of an assembly of unit ropes known as ''reddies'', each with
four strands, whereby usually six, eight or ten reddies are laid side by side with
alternating left and right direction of lay (therefore non-rotating) and are then held
in position by stitching wires, strands or rivets. In Fig. 1.36 b a flat rope is to be
seen from the top and in cross-section. Flat ropes are normally used as balance
ropes in pit hoistings.
1.5.3 Designation of Wire Ropes
The designation of wire ropes follows ISO17893:2003(E). The system for desig-
nating steel wire ropes details the minimum amount of information that is required
to describe a rope. The system is capable of accommodating most rope con-
structions, strength grades, wire finishes and layers of steel wire ropes. The
symbols for the designation of wire ropes are given in Table 1.7 with the symbols
for the core in Table 1.5 . The following examples show how this designation
works.