T.J. Boeschoten en N.R.J. Langenkamp
Negatieve kruip op tractieschijf met halfronde groef.
Report 94.3.TT.4367, Transport Engineering and Logistics.
The application of more elastic materials and the increasing need to know
the effects of relative displacements of cables on traction sheaves on the
cable life, make it necessary to examine besides the forces also the
So far this had been done by using Eytelwein's theory, but technical
developments increase the gap between theory and reality, and are the reason
that Eytelwein's theory has become less reliable.
By using a built-in endoscope with a video-camera and a frame-grabber
computer programme, the behaviour of the cable on a traction sheave and
especially the displacements, were examined. This was done for
traction-ratio's 1.25 and 1.35, while releasing the cable. A strain gauge
was used to measure the stress at the surface of the cable, on the same
location as where the displacements were measured.
The experiments showed that, while driving the traction sheave, the position
of the cable on the sheave hardly changes, except for a location at about
two thirds of the area where the cable lies on the sheave. On that location
the creep-direction suddenly turns to negative.
The negative creep is an effect of small elements of the cable, caused by a
varying internal friction and a change of shape of the other cable-elements.
These effects have much influence on cable behaviour because of the
relatively low cable load, when compared to the maximal cable load.
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