1) The use of bogies on vehicles is to increase the load, length and volume of the vehicles and to improve the running speed of the trains to meet the needs of railway transportation development;

2) Ensure that under normal operating conditions, the car body can be reliably seated on the bogie, and the rolling of the wheel along the rail is converted into the translation of the car body along the line through the bearing device;

3) Support the vehicle body to withstand and transmit various loads and forces from the vehicle body to the wheels or from the wheel rails to the vehicle body, and evenly distribute the axle weight.

4) Ensure the safe operation of the vehicle, and flexibly run along the straight line and smoothly pass the curve.

5) The structure of the bogie should be easy to install the spring damping device, so that it has good vibration damping characteristics to ease the interaction between the vehicle and the line, reduce vibration and impact, reduce dynamic stress, and improve the smooth running of the vehicle. Sex and safety.

6) Make full use of the adhesion between the wheel and rail, transmit the traction and braking force, and amplify the braking force generated by the brake cylinder, so that the vehicle has a good braking effect to ensure parking within a specified distance.

7) The bogie is a separate component of the vehicle, minimizing the coupling between the bogie and the body.