Wheel/Rail Adhesion Under Plastic Bags Contamination Condition

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Date

2015-05

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Publisher

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.

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Keywords

Wheel tread–railhead contact, plastics contaminants, Adhesion, Slip, Twin disc

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