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2026
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03
How much responsibility does the dryer tank have for the phenomenon of the trailer's trailer relay valve being frozen?
The weather has been getting colder recently, and some car owners have reported that the trailer relay valve often gets frozen. They suspected that the backblow effect of the air dryer was not good, so they modified the air dryer to an independent backblow tank type. However, judging from the fault symptoms and the temperature measurement at the intake, the failure of the frozen trailer valve is not closely related to the type of air dryer.
The intake of a truck dryer often exceeds 70 degrees, while the maximum temperature for the dryer intake is 65 degrees. Only when the intake is within this temperature can the dryer work efficiently. Therefore, the core reason for the frozen valve failure is not entirely due to the dryer’s purge type; rather, it is that the intake temperature is too high. Here, it is only necessary to reduce the temperature of the dryer intake by adding a spiral tube to completely eliminate the frozen valve failure.
Air Dryer
The air dryer is basically already a standard component on air-braked trucks. Its function is to remove moisture from the compressed air, turning it into dry air, ensuring the air used for the truck's brakes remains dry. In winter’s low temperatures, the moisture in the air will not condense in the pump valves, causing brake failure and brake dragging faults. The dryer is like a sponge; after it absorbs enough water, it stops working. So what is the way to remove water from the drying particles like wringing out a sponge, in order to extend the life of the dryer?
The main ingredient in the drying tank is a lot of particles that absorb water
The main ingredients in the drying tank are a lot of water-absorbing particles, which can be understood as common sponges in life. You can imagine that after the sponge is full of water, you have to wring it out before it can absorb water again. The same is true for particles in the drying tank, if the absorbed water is not removed in time, it will quickly absorb water and lose its effect.
So how to achieve the purpose of removing water? After the compressed air reaches the specified air pressure and the discharge valve is unloaded, the dried air is used to blow the drying tank in turn to achieve the purpose of removing moisture, which is the blowback regeneration device on the drying tank.
The blowback form has two purposes, both of which are to extend the life
One is independent gas cylinder blowback
There is an independent small gas cylinder with a capacity of 5 liters, which is connected in parallel to the air outlet of the dryer, and when pressurizing the gas cylinder, this small gas cylinder is also inflated at the same time. After the specified air pressure is reached, the dryer depressurizes, and the dry air in this small cylinder in turn blows out the moisture inside through the dryer. This form of blowback regeneration is easy to identify, and you only need to find the small gas cylinder along the air path to identify it.
The other is to use the vehicle's own gas cylinder
After the dryer is unloaded, a part of the dried air is returned to the dryer, using this blowback form of dryer, there will be a return valve on the dryer valve body, and after unloading, it can be seen on the air pressure gauge, one of the air pressure gauges will drop the pressure of about 50kpa, which is the process of using its own gas cylinder air pressure to blow back the drying tank.
The purpose of both blowback methods is the same, both of which can play a role in extending the life of the dryer and making the dryer work more efficiently. But many cardholders' cars have this device, and they also regularly replace the drying tank, why is there still water in the air path?
In winter, the air brake pump valve is frozen, either there is no brake, or the brake is delayed and does not return to position. Both of these faults seriously affect driving safety, and many card friends do not seriously analyze the root cause of the fault, blindly replace the dryer, causing their own economic waste, and the elimination of the fault is not helpful. Here we hope that the maintenance friends can confirm and really analyze the cause of the failure, and do not blindly replace and modify.
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