Factors of wheel flats occurrence and preventive measures

Abstract Wheel flats, caused by the braking of rolling stock, bring not only vibration and noise into vehicles but also cause mechanical damage to bearings and axles. The authors began to study preventive measures against wheel flats by organizing the Flat Countermeasure Workshop with engineers of 18 major railway companies in Japan. As a result of the investigation in the workshop, some factors which reduce the adhesion coefficient between running wheels and rails are considered. The influence of brake shoes and tread surface roughness upon the reduction of adhesion are investigated for a few existing electric commuter railcars. The relationship between car mileage and flat occurrence is briefly reported. In addition, a new classification of wheel tread damage is introduced in order to compare the degree of flat occurrence between railway companies.