Hoisting ropes are constructed of wires and strands positioned
helically around the axis. This helical positioning causes that, in
the rope loaded at the end with the weight Q, the longitudinal
displacement u, axial force P, torsional displacement v and
constant torsional moment M are generated. More over, the proper weight of the rope q gives the force
acting along the axis of the rope. This force changes its value
from 0 at the bottom to qL at the top. This force gives, along its
length, a variable torsional moment making the rope rotate. During the movement of the conveyance downwards the
falling part of the rope rotates, which makes it untwist on the
section up to the half-depth of the shaft and twist on the other
half-depth. As the result, the twisting lay of the rope changes
increasing in the upward direction and decreasing downwards.
The angle of twist of the strands changes in an apposite way.
When moving upwards, the uplifted rope does not twist and
retains its state of deformation up to the moment when it passes
over the pulley. Next, the cycle of untwisting and twisting repeats
during the movement of the other conveyance downwards. This phenomenon is known from mining practice. It was also
analysed, in the works of Glushko (1966) and Popowicz (1963).