What is the most important thing when buying a semi-trailer?

When the main truck and the trailer are connected, the height of the trailer leg is adjusted to ensure that the lower plane of the trailer traction plate is lower than the upper plane of the main truck saddle 1-3CM. If the height is too high or too low, the main suspension cannot be combined. If it is serious, it will cause the saddle. The wear ring of the seat, the hook of the lock and the surface of the traction plate are damaged by bumps.

When the tractor is going backwards, try to align the tractor to ensure that the tractor is in line with the centerline of the semi-trailer. Generally, the horizontal offset of the two centerlines cannot exceed 4cm. The angle between the two centerlines is limited to 5° when fully loaded, and the space is limited to 7° when empty.