Trailer balance beam and axle pin knowledge

▎What are balance beams and axle pins?

Conventional trailer suspension structures are mostly found in leaf springs, airbag suspensions and a rare rubber suspension. Among them, the leaf spring suspension has more advantages in economy and load capacity, and the balance beam and axle pin are part of the leaf spring suspension structure. Next, we will introduce their functions and damage symptoms.

Balance beam: The trailer balance beam is located in the middle of the front and rear two sets of leaf springs. Its working principle is like a "seesaw". As a fixed point of the steel plate floating frame, it also plays a role in balancing the bearing capacity between the axles. , so that the force on each axle is more even when the vehicle is driving on the undulating road.

Generally, the balance beam is not easy to be damaged, unless the load is too large, which causes the steel plate floating frame and the top of the balance beam to wear too much, and all the force is applied to the axle pin, so that the steel plate bracket and the balance beam are combined together.

The most common damage to the balance beam is on heavy-duty vehicles, usually a crack in the solder joint on the top of the balance beam. After all, this is a fixed part of the chassis structure, and it has been welded when the trailer leaves the factory. If it is a standard model, it is almost free of replacement for life, as long as the axle pins and bearing holes are welded and replaced.

(2) Shaft pin: In fact, from the structural point of view, this shaft pin and the balance beam should be combined into one, the reason why they are introduced separately here is precisely because when replacing it, it needs to be noted that if the wear of the base of the balance beam is not so serious that the bearing hole cannot be repaired by welding, only the shaft pin needs to be replaced.

▎Replacement cost and maintenance cycle

The maintenance and replacement cycle of the balance beam bearing hole and axle pin of the ordinary leaf spring suspension depends on the driving road conditions and the number of kilometers.

If it is standard load transportation, high-speed road conditions are the main operation conditions, and national road conditions are supplemented, and the round-trip heavy load is about 34-35 tons, then the maintenance period of the axle pin is about 10,000 kilometers. It needs to be lubricated during maintenance. During lubrication, you can also check the gap between the shaft pin and the bearing hole of the balance beam. If it is loose, it means that the replacement cycle is reached.

According to the description of the repairman, the safe replacement cycle for both of the above operating conditions is one year or 200,000 kilometers. The overall replacement of the balance beam bearing hole and axle pin can avoid tire failure. If the trailer has ABS, it will also affect the effect of ABS.

▎What are the side effects of damage to the balance beam bearing hole and shaft pin?

First, it will lead to different bearing capacity between the axles, ordinary three-axle trailer in no load, heavy load, the three axle load distribution is not uniform, the vehicle in the brake, the bearing capacity of the smaller wheels will be more likely to hold the situation.

When the vehicle is in an emergency deceleration, there will always be an axle with uneven braking force, which will easily wear the tires and reduce the braking force.

In a word, a vehicle is composed of countless parts and components. The failure of any part will make the vehicle unable to drive. When the vehicle is faulty, it should be discovered and repaired as soon as possible to avoid major damage caused by small faults to gain greater profits.