Коефіцієнти тертя між колесами залізничного транспорту і гальмовими колодками з чавуну та композиційного матеріалу: порівняльний аналіз

• Date: 2023
• Main Author: Сіренко, Катерина
• Format: Article
• Language: Ukrainian
• Published: Physico-technological Institute of Metals and Alloys 2023
• Subjects: коефіцієнт тертя; гальмові колодки; чавун; композиційні матеріали; стандартизація
• Online Access: https://www.metalsandcasting.com/index.php/mcu/article/view/11
• Journal Title: Metal and Casting of Ukraine

The coefficient of friction on the contact surface of brake pads made of cast iron and composite materials (rubber-asbestos or rubber-asbestos-free mixture) and wheels of railway rolling stock is analyzed. The values of friction coefficients in standards and technical conditions for brake pads are compared. The range of coefficients of friction (0.20–0.30) of cast-iron pads on the surface of the wheels specified in the regulations is much smaller than the range of friction coefficients of composite pads (0.34–0.65) and composite pads with cast-iron inserts (0.35–0.50). It is shown that the total value of the coefficient of friction of composite pads with cast-iron inserts, which summarizes the coefficients of friction of the wheel surface with composite and cast iron, is strictly uncertain because each material reacts differently to the same friction conditions. It is proposed to consider the value of the coefficient of friction of a composite pad with cast-iron inserts from the standpoint of a plausible approach in the form of a field of distribution of a random variable. The mechanism of influence of moisture (water) on the coefficient of friction between the surfaces of the brake pad and the wheel is considered. The regularities of changes in the force and coefficient of friction of the pad on the wheel at the initial stage of emergency braking of the railway train are revealed. The results of experimental research of friction coefficients of composite material and cast iron with wheel steel are presented. It is emphasized that the brake pads made of composite material contribute to the emergence of defects on the rolling surface of the wheels of railway transport. To ensure the stability of the friction coefficient of composite brake pads, it is recommended to regulate in standards and specifications the list and chemical composition of components, substances that make up the composite material (rubber mixtures), as formulated in the standards requirements for cast-iron pads.