Under the implementation of the national standard GB7258, the traction of trailers has also been greatly affected. In addition to the change of truck charging to axle charging, another important standard is that many trailers should be equipped with disc brakes and air bag suspension axles as standard.

Most of the trailers we run on the road now are rigid suspension and drum brake. If all the newly licensed trailers are changed to disc brake and airbag suspension, the purchase cost of car owners will be much higher.

The figure shows the disc axle and drum axle. First, let's talk about the difference between the footwall brake and drum brake. The most fundamental difference between the two is the difference in heat dissipation. The disc brake has better heat dissipation and is not prone to heat recession during long-term high-intensity braking. Now passenger cars are basically four-wheel disc brakes, and the models with front disc and rear drum are basically used in low configuration models.

The advantage of drum brake is that it is cheap. The cost of drum brake is very cheap. The general speed of heavy trucks is not high. The durability of brake shoes is better than that of disc brake. The diameter of brake drum of drum brake device is much smaller than that of disc brake. Therefore, many heavy vehicles still use four-wheel drum design.

Disadvantages: the drum brake force is large, but the heat attenuation is obvious and the heat dissipation is poor. Because the brake working mechanism is closed in the brake drum, the contact surface between the brake drum and the brake pad will become smaller after thermal expansion. After continuous braking, the heat cannot be dissipated quickly, affecting the braking efficiency, and may also cause axle damage and other problems.

The heat dissipation of disc brake is much better than drum brake. There will be no heat attenuation in continuous brake, resulting in brake failure. Even if the temperature of brake disc increases and the size becomes larger, it will not change the braking effect.

Then, the disc brake system responds quickly and can do high-frequency braking action, so it is more in line with the requirements of ABS / EBS system. Finally, the disc brake does not have the automatic braking effect of the drum brake, so the braking force of the left and right wheels is relatively average.

Disadvantages: compared with drum brake, disc brake is more expensive. At the same time, compared with drum brake with the same size of brake disc, the braking force of disc brake is weaker than drum brake. Therefore, disc brake must be used together with other auxiliary brakes. For heavy-duty trucks, disc brake is not so advantageous, and it needs the large braking torque of drum brake.

Indeed, at present, except for dangerous chemical models, other models almost still use drum braking. But here we need to emphasize that this does not mean that disc braking is worse than drum braking, because disc braking must have auxiliary braking and supporting suspension support, and disc braking will also have more advantages under a series of complete supporting conditions.

So if you were the car owner, what kind of axle would you choose to buy?