Wheel/Rail Adhesion Under Plastic Bags Contamination Condition
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Date
2015-05
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Addis Ababa University
Abstract
Railway vehicles require a certain level of adhesion between wheel and rail to operate
efficiently, reliably, and economically. Different levels of adhesion are needed depending on the
vehicle running conditions. In the wheel tread–railhead contact, the dominant problem is low
adhesion, as low adhesion on the railhead negatively affects railway operation: on one hand, the
vehicle will lose traction resulting in delay when driving on low-adhesion tracks; on the other
hand, low adhesion during deceleration will extend the braking distance, which is a safety issue.
This thesis examines the influence of plastic bags contaminants on the adhesion in the wheel
tread–railhead contact. This study will improve our knowledge of the low-adhesion mechanism
and of how plastics contaminants influence adhesion.
In this thesis, the adhesion conditions of four groups of plastics ; group one, group two, group
three and group four with corresponding thicknesses 0.00185mm, 0.0025mm, 0.0035mm and
0.007mm respectively were assessed using a twin disc test machine. Thus the research
methodology used was a laboratory test. The test procedure and/or the test set up followed in this
work was the set up described in [6] except the method of application of tested contaminants on
the rail wheel due to the difference in contaminants considered. The aim of this work was to
study the extent of adhesion coefficients in the contacts of wheel-rail rollers over a range of slip
values with and without plastic bags contaminants. Thus the outcomes from lab test were the
coefficients of adhesions of each contaminant within 0, 0.25, 0.5, 1, 2 to 10% slip values so as to
sort out weather plastics contaminants will affect wheel-rail adhesion. The result of this
experimental test shows that the adhesion coefficient due to plastic bags contaminated condition
is much less than that of the dry test. The variation in wheel-rail adhesion ranges up to 88%.
From the result it is concluded that plastics bags adversely reduce wheel-rail adhesion.
Description
Keywords
Wheel tread–railhead contact, plastics contaminants, Adhesion, Slip, Twin disc