EXTENT OF ADHESION LOSSES IN THE WHEEL-RAIL CONTACT UNDER CONTAMINATED CONDITIONS

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 and on
the other, low adhesion during deceleration will extend
the braking distance, which is a safety issue.
This research work examines the influence of the
contaminants, i.e., water, mud, leaves, oil and
grease, with a twin disc machine which is designed
and constructed as part of this study to simulate
wheel tread-railhead contact. Thus, the research
methodology is a laboratory test without and with
the different contaminants aimed at studying the extent
of adhesion coefficients of each contaminant
over the range of slip values 0 to 10% and comparing
which of them are the worst to cause loss of adhesion.
As the lab results revealed, oil, grease and
water have been found to cause less adhesions than
leaves. Unlike the research made justifying leaves,
they were found the worst in causing adhesion losses.