Song reversed the car.

This problem is because the time that the vehicle travels forward accounts for 99% of the vehicle mileage. When braking, the brake pad and the brake disc wear in one direction for a long time, and there are certain metal components in the brake pad, resulting in some metal burrs on one side of the brake pad. When you step on the brake when reversing, the tips of these burrs will contact with the brake disc, which is the main reason for abnormal noise and is normal.

Although there are many kinds of vehicles, their structures are similar. This should be said to be the credit of standardization and the need of large-scale production line. With the development of society, the progress of science and technology and the change of demand, the appearance of railway vehicles has also begun to change, especially the passenger cars are no longer the same old faces. However, their basic structure has not changed obviously, but the specific parts have more scientific and advanced structural design.

Generally speaking, the basic structure of a vehicle consists of five parts: body, underframe, running gear, coupler buffer device and braking device.

The car body is the part of the vehicle carrying goods or passengers, and it is also the basis for installing and connecting other parts of the vehicle. The bodies of early vehicles were mostly wooden structures, supplemented by steel plates and bow bars. Modern automobile body is mainly steel structure or light metal structure.