Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 33

A good method is to let it fall drop by drop from a pump onto a slightly opened
rope (where it is bent over a sheave). Lubricants with very high viscosity can only
be inserted into the inner rope with lubricating devices. Verreet ( 1989 ) describes
such a device with a pressure sleeve. Oplatka ( 1984 ) presents another device
which injects the lubricant with pressure between the strand lanes.
1.4.3 Rope Endurance
Of all the influences on the endurance of running ropes provided by the rope itself,
lubrication has the greatest effect. To evaluate this influence, Müller ( 1966 ) made
bending tests with a lubricated and a de-lubricated Filler rope. In these tests, the
endurance of the de-lubricated rope only reached 15-20 % of that reached by the
lubricated rope, Sect. 3.2.2 .
Müller ( 1977 ) also found that lubricated wire ropes had an advantage in the
case of tensile fatigue tests. For different stranded ropes, he found that de-lubri-
cated wire ropes have an endurance of about 75 % of that found with lubricated
ropes, Sect. 2.6.3 . Lubrication reduces the friction between the wires in strands
periodically bent by fluctuating tensile forces, Andorfer ( 1983 ). With the reduction
in friction, the secondary tensile stress in the wires will also be reduced and the
endurance will thus be increased.
In most cases, the lubrication provided by the manufacturing of the wire rope
will be enough for the entire life of the rope. Bending tests showed that, up to a
breaking number of bending cycles of about N = 80,000, giving the wire rope an
additional lubrication during the test did not increase its endurance, Feyrer ( 1998 ).
When re-lubricated, the endurance of the wire ropes will be increased if the
endurance of the wire rope without this re-lubrication is greater than about number
of bending cycles N = 80,000. For example, in a series of bending tests, the mean
breaking number of bending cycles increases from N = 246,000 to 392,000 when
re-lubricated, Sect. 3.2.2 .
1.5 Wire Ropes
1.5.1 The Classification of Ropes According to Usage
Depending on where they are used, wire ropes have to fulfil different requirements.
The main uses are depicted in Fig. 1.30 . Running ropes are bent over sheaves and
drums. They are therefore stressed mainly by bending and secondly by tension.
Stationary ropes (stay ropes) have to carry tensile forces and are therefore mainly
loaded by static and fluctuating tensile stresses. Track ropes have to act as rails for