球状黒鉛鑄鐵の車輛用制輪子への應用

Abstract

Spheroidal graphite cast iron has many good properties as an industrial material, because of its special type of graphite. Wear resisting properties of this material has been expected to be excellent since advent of spheroidal graphite cast iron. Especially, in a dry wear condition spheroidal iron is said to be superior to other types of cast iron. Much research on the wear properties this material has been made by many investigators in Japan but their opinions about wear properties of spheroidal iron differed from each other and various experimental results were obtained. Naturally, complexity of substantial wearing mechanism and diversity of experimental conditions of wearing tests caused these discrepancies. Accordingly, to permit the wearing properties of the spheroidal graphite iron to be clear, experiments should be made in practical conditions. In this report the authors compared the life of spheroidal iron brake shoes with grey iron brake shoes which had been attached to electric tram cars The results were obtained in which the wear loss by grey iron brake shoe was about three times as spheroidal iron. The authors also made brake tests with the same tram car using two types of cast iron brake shoes which were used in the wearing tests. In brake tests retardation curves were recorded by using a self-recording acceleration meter. From these retardation curves the friction coefficients between brake shoes and tires were calculated in various experimental conditions. Thus the brake·effects of these two types of cast iron brake shoes could be compared. The results were such that the friction coefficient of spheroidal iron brake shoe was larger than that of the grey iron shoes when car velocity was raised up to more than 43 kilometers per hour.