Experimental study on the effect of formulation modification on the properties of organic composite railway brake shoe

Friction materials used to manufacture railway brake shoes are assessed with consideration of a wide variety of their functional, frictional and mechanical properties. To meet the versatile requirements posed by brake system manufacturers and railway operators, formulation of contemporary organic composite friction materials are fairly complex containing in some cases even more than a dozen different ingredients. To conduct the design process of new materials effectively, it is necessary to understand the influence of individual raw materials on properties of the composite. In this study two organic composite friction materials were compared extensively allowing for investigation of influence of two ingredients, namely quartz and petroleum coke, on the properties of the composite. Discussion of results includes analysis of instantaneous and mean dynamic coefficient of friction in relation to initial velocity, contact force and temperature. Both full- and reduced-scale dynamometer test results are discussed. In addition, the mechanical properties of the materials are presented and compared. All tested characteristics were influenced by the formulation modification. The effect was pronounced enough to allow drawing conclusions on qualitative relation between formulation and properties of the composite friction material.