The railway locomotive and vehicle axle system adopts different structural design due to different application conditions. The locomotive and passenger car have axle box, and the bearing is connected with the bogie through the axle box. The railway freight car has no axle box, and the bearing is connected with the bogie side frame through the bearing saddle. Bearings bear the impact load generated between the wheelset and the bogie frame, and also bear the axial load generated by the turning of the vehicle.

Axle bearing structure comprises cylindrical roller bearing, cylindrical roller bearing unit, tapered roller bearing and tapered roller bearing unit. According to the application requirements of railway bearings, axle bearings should have a long maintenance-free period, convenient maintenance structure design and high reliability. Railway vehicle axle bearings are divided into the following types according to the design technology and application of their models: cylindrical roller bearings, single double row tapered roller bearings, single row tapered roller bearings, single row cylindrical roller bearings, cylindrical roller bearings, and single cylindrical roller bearings. The unit is mainly used in railway locomotives, passenger cars, urban rail vehicles axle boxes, generally double row cylindrical roller bearings with sealing devices on both sides or two paired single-row cylindrical roller bearings with sealing devices on both sides. The bearing unit has been filled with grease before the supply installation, and no grease is added during installation.

Because the bearing has an integral sealing device, it has a long maintenance cycle. This type of bearing has a special structural design inside, and the modified linear contact between the roller and the raceway avoids edge stress, making the bearing particularly suitable for bearing high radial loads in applications, but also able to withstand some axial loads. Compared with tapered roller bearing units, cylindrical roller bearing units are easy to disassemble and assemble, which is convenient for bearing inspection and maintenance.

Double row cylindrical roller bearings, single row cylindrical roller bearings with unit pairs, single row tapered roller bearings, unit bearing units with complete sealing, have been filled with grease and adjusted clearance before supply installation, the integral unit design facilitates the installation and removal of bearings, bearings are pressed on the journal by cold mounting method.