Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 31

Fig. 1.29 Steel cores in wire

ropes

wire strand core
WSC

independent
wire rope core
IWRC

parallel wire rope
core with strands
PWRC

wire rope core
enveloped with
solid polymer
ESWRC

Wire ropes with steel cores covered with solid polymer (ESWRC) and those
with steel cores enclosed parallel with the outer strands (PWRC) have better
bending endurance than wire ropes with a not covered independent wire rope core.
Here, it is not necessary to have only small clearance between the outer strands,
Wolf ( 1987 ). The reason is that in this case the outer strands are very well bedded
by the core as in the case of fibre cores.

1.4 Lubrication

1.4.1 Lubricant

When a wire rope is bent considerably, the wires and the strands move against
each other. Relative movements also occur between the wires in stranded ropes
changing the tensile forces by friction, Schmidt ( 1964 ). There are also movements
between wire ropes and sheaves, especially in the case of wire rope side deflection