Trailer, as the name suggests, refers to a vehicle without its own driving power that is mounted on the towing main vehicle. The trailer itself has no driving power and needs to be towed by the towing vehicle. Since the trailer relies on the main vehicle, there is a problem of coordination and matching between the main vehicle and the trailer. The design and production of the trailer are determined by the main vehicle rather than unified configuration, and of course, it cannot be randomly matched, otherwise it will bring many problems to the performance of the trailer train. Below, we will share with you the commonly used parameters for towing the main vehicle during the matching design of the main trailer.

1. Tractor saddle height

1.1. Definition of Tractor Saddle Height: Refers to the height above the ground of the upper plane of the tractor (tractor) saddle, which is the vertical distance H between the upper plane of the saddle and the horizontal ground when the saddle is placed horizontally. Saddle height can be divided into heavy-duty saddle height and unloaded saddle height (usually only the unloaded saddle height is reported and referenced when designing trailers).

1.2 Design purpose of tractor saddle height parameters

★ The saddle height H of the tractor is one of the three important design parameters and must be reported in the main trailer matching design;

★ The saddle height H of the tractor is a fundamental and essential data for the design of various types of semi-trailers. Without providing saddle height trailers, it will be impossible to design and manufacture them;

The saddle height H of the towing vehicle determines the height of the cargo carrying surface of the trailer (i.e. the height of the bearing);

The saddle height H of the tractor determines the selected suspension height for the trailer during design.

1.3. Measurement method for saddle height parameters of towing vehicles

1.3.1. First, park the tractor on a hard and flat surface;

1.3.2. Place the tractor saddle in a horizontal position;

1.3.3. Use a measuring ruler or steel tape measure at least 1.5 meters to measure the vertical distance from the highest surface of the saddle to the ground.

1.4 National technical standards and requirements for tractor saddle height parameters

1.4.1. Under no-load conditions, the height of the tractor saddle shall not exceed 1400mm.

1.4.2. The saddle height of the towing vehicle for transporting standard containers with a height of 2591mm under unloaded conditions shall not exceed 1320mm.

1.4.3. The height of the towing vehicle saddle for transporting standard containers with a height of 2896mm under unloaded conditions shall not exceed 1110mm.

1.4.4. Under heavy load conditions, the height of the towing saddle of ordinary semi-trailers (excluding skeleton vehicles) is between 1150mm and 1300mm.

1.5. Reporting and matching precautions for tractor saddle height parameters

1.5.1. Due to the diversity of tractor manufacturers and different design standards, there are significant differences in the saddle height among manufacturers. Even for the same model of tractor from the same manufacturer, the saddle height varies due to the number of rear bridge plate springs and the form of saddle pads. Therefore, when reporting the saddle height of tractor, it is advisable to use the measured parameters as much as possible!

1.5.2. When matching the height of the tractor saddle, it is recommended to have an upper deviation of less than 1cm and a lower deviation of less than 1.5cm.

1.5.3. When matching the height of the towing vehicle saddle, there is a large upward deviation (i.e. the main vehicle saddle is too high):

★ Semi trailer front axle load decreases, front axle tires are worn flat

★ Increased axle load at the saddle of the tractor, insufficient vehicle steering, or uphill tilting when starting