Wire Ropes Under Bending and Tensile Stresses - Wire Ropes: Tension, Endurance, Reliability - page 309

Data:

The data are the same as in Example 3.14.
The bending length is again l = 40 m.
The rope balance mass ratio is c = S b /s.
Acceleration zone DL ¼ v 0 = 2a 0
Rope length mass factor W = 0.367/100
The rope piece L 0 not running onto the drum and the
attachment is counted as part of the cage mass.

X

L

I

L

0

II

Analysis:
Loading sequence The rope l will be stressed by one

combined rope rope l fluctating tension
and bending cycle during one working
cycle (up and down movement of the
cage)

Loading sequences
rope I

w com ¼ 1 :

Rope ll The rope ll will be stressed in addition

by reverse bendings, one in up- and one
in down moving of the cage ll. Then
the loading elements are

rope II

w com ¼ 1 and w rev ¼ 2 :

Tensile forces:
The reduction of the tensile force that occurs by unloading Q will be neglected.
The wire rope is subject to different tensile forces over the entire length when
running onto the drum. When running the rope onto the drum, the tensile force
in the rope element at the distance x to the cage is

S ¼ ð F þ Q þ W d 2 x þ W d 2 ð L x Þ c Þð g þ a Þþ K :

In this equation, a is to be put in for DL (the acceleration and braking distance)
and for L (the hoisting distance).

a ¼ a 0 for L DL\ L

a ¼ 0 for DL\ L DL

a ¼ a 0 for 0\ DL :

The minimum tensile force in a rope element at the distance x to the cage exists
when the cage is standing in the lower station