High-speed trains, subway vehicles and urban light rail transit operate under long-distance variable load, frequent start-stop vibration and alternating cold-hot climate environment, putting high reliability requirement on axle box bearing and auxiliary transmission bearing inside rail vehicles. Silicon nitride balls have been gradually applied on high-end new-generation rail transit vehicle precision bearings to upgrade vehicle operation safety and component service life.
Rail vehicle axle bears huge vehicle body weight and instantaneous dynamic impact load during track uneven section passing, requiring bearing rolling elements with strong compression resistance and fatigue resistance. High-hardness silicon nitride balls bear long-term alternating heavy load without permanent indentation deformation, maintaining stable bearing clearance and wheel rotating precision; effectively avoiding vehicle wheel clamping stagnation risk caused by steel ball plastic deformation after long mileage operation.
Railway vehicles run across different regions with variable climate, from high-temperature southern coastal humid salt fog environment to cold northern low-temperature frost weather. Ordinary steel bearing balls easily rust in coastal salt spray atmosphere and suffer cold brittleness under frigid temperature, while silicon nitride balls adapt wide-range temperature and humidity change without corrosion or performance deterioration, ensuring stable bearing performance all year round for long-distance running rail equipment.
Frequent acceleration and deceleration of urban subway generate continuous cyclic friction on transmission bearing components, accelerating wear speed of traditional steel rolling parts and increasing later maintenance workload of vehicle repair depot. Silicon nitride balls’ excellent wear resistance extends bearing overhaul cycle by multiple times, reduces vehicle offline maintenance frequency and improves rail transit line operating efficiency.
Besides vehicle axle bearings, small-size precision silicon nitride balls are configured on rail vehicle door drive bearings and brake system auxiliary rolling parts, improving brake response precision and automatic door smooth operation performance. With continuous development of global high-speed railway construction, silicon nitride balls become important lightweight upgrading material for new-type railway vehicle core bearing components.
