Trailers have a large load-bearing capacity and strong inertia, and their braking system bears relatively higher pressure, especially when facing long downhill or rough mountain roads that require frequent brake application. The axle brakes often overheat due to high braking pressure. If not cooled down in a timely manner, it is easy to cause the brakes to overheat and affect braking safety.

To address this issue, many car owners have made improvements in their vehicle configuration and driving habits, such as using engine assisted braking or installing auxiliary braking devices such as water cooling devices and hydraulic retarders. This is also a common solution to brake overheating.

However, these common solutions are not without drawbacks. Taking drenching for cooling, although it is cheap, easy to install, and has obvious cooling effects, it does not have an advantage in weight and occupies the weight space of goods. In cold winter, it can also easily cause road icing and affect driving safety.

So, various new inventions and products emerged, such as water-cooled axles, disc brakes, wheel brakes, and so on, which many car owners have heard of. When it was first launched, it was very popular and had a strong sense of ambiguity; But after a period of time, it failed to gain popularity and even gradually began to disappear. Today, let's take a look at the axles that sound tall but have not been widely used.

1. Water-cooled axle

Structurally, it is composed of a water storage tank, a radiator, and several pipes. Its working principle is that the electric water pump drives the water in the tank to enter the wheel hubs at both ends through the pipes in the center of the shaft pipe. Then, the water distributor enters the interlayer of the brake drum for cooling, and then the water distributor returns to the water tank, repeating the cycle.

Simply put, a water-cooled axle can be equivalent to an improved and upgraded water spraying device, but the water spraying device does not have a reflux function. After the water is poured onto the brake drum to cool down, it falls onto the road surface, so it needs to be continuously added with water; The water cooling device can achieve internal circulation of water flow. After the cold water reaches the brake drum and cools down, it can return to the water tank again, without wetting the road surface or adding water frequently.

In principle, it works. However, what is the self cooling ability of such a sealed internal circulation system? The temperature of the water returning from the brake drum is too high. During continuous circulation, if the self cooling performance is not up to standard and encountering long downhill roads, the water tank may directly boil.

Furthermore, the process of internal water circulation cannot be observed by car owners from the outside, and it is also unknown whether the water circulation is smooth. Once the pipeline is blocked and the water flow stops moving, there is no way to talk about cooling. If the car is not equipped with a relevant alarm system, driving safety may be difficult to guarantee. In addition, whether the water tank and pipelines will freeze in severe cold weather is also a question to consider.

It is also because these questions have not been fully tested in the market yet, although water-cooled axles were introduced as early as 2017, they have not yet been widely used.

2. Circumferential disc brake

A circumferential disc brake is a type of brake that includes a circumferential brake disc, a circumferential clamping brake shoe, and a brake actuator. This type of brake is designed with brake pads on both inner and outer sides of the brake drum. When the car owner presses the brake, the inside is stretched outward, while the outside is also tightened inward, resulting in greater braking force.

In addition, the brake drum is not sealed, and the brake pads are exposed to the air, resulting in higher heat dissipation performance. The design also adds air guides. As the wheel speed increases, the air guides will blow into the interior of the brake to help dissipate heat.

If viewed solely from its appearance, this type of brake is more like a combination of drum brake and disc brake. According to design requirements, it can be applied to commercial vehicle fields such as heavy, medium, light, and passenger vehicles.

However, this type of brake has an awkward problem: its name is "disc type", but its structure is like "drum type". Until now, regulations have not explicitly recognized whether it belongs to "disc type" or "drum type", and many car owners are worried about being fined after driving and dare not easily install and use it. Moreover, although it may be tempting in principle, there is currently a lack of practical verification on whether it can bring excellent braking and heat dissipation performance when put into use, so car owners dare not easily become "mice".

3. Wheel brake

According to relevant information, wheel brakes belong to a type of drum axle, which adopts a tightly closed and semi open braking method, combined with oil cooling and air cooling. The brake drum has been removed, making it simpler in structure and more versatile. It is suitable for all current commercial vehicle axle models, including support axles.

From the perspective of introduction, wheel brakes "are a cutting-edge technology axle that combines the advantages of disc brake axles and drum brake axles." This seems to be quite similar to circumferential disc brakes. As for whether they are products of the same design principle, as I have not yet found a design diagram of wheel brakes for trailers, I cannot make a hasty decision.

The legend of the drive axle using wheel brake is shown in the following figure, but the details of the wheel end are not clearly displayed, making it impossible to determine whether it is equivalent to a circumferential disc brake.

The wheel brake was interviewed and reported by CCTV Science and Education Channel at that time, and its popularity was unparalleled. However, it has not been widely applied today due to the lack of actual data support, just like the previous two types of axles. Many car owners also expressed that the design of wheel brakes is not scientific, sand and dust can easily enter the brake drum, and brake pads are easily scrapped.

At present, the application prospects of hydraulic retarders are relatively broad in the current issue of trailer brake cooling. In addition to its own advantages, the implementation and enforcement of regulations are also important factors. In fact, the emergence of any new thing always brings both advantages and disadvantages, and the cooling of trailer brakes is not an overnight problem. Only by constantly innovating, constantly trying, striving from zero to one, comprehensively considering and improving the resolution of relevant doubts, as long as the product quality is qualified, I believe that users will still help new products open up the market.