The double-chamber air chamber is inconspicuous and poorly maintained, turning into a time bomb

Speaking of the double-chamber air chamber, I believe that many people are still a little unfamiliar with this name, but when it comes to one of the components of the air chamber, "leather bowl", it is much more famous, the structure of the truck vehicle is different from that of small vehicles, due to the weight of the vehicle, strong inertia, when stopping and resting and braking and deceleration, it is necessary to rely on the strong braking force of the pneumatic brake, today we will learn about the brake chamber.

▎ Practical case There is no danger

Today with a master in the chat, discussed this year's transport market, but also asked the gas chamber "leather bowl" problem, now also with the card friends to share this actual case, Master Zheng is at the door of the 319 National Highway, for which it provides a great driving convenience, every time after loading the goods home is to park the car at the door of the house, to set off to unload when the car reversing out.

Then the problem is here, the door of the house and the road surface of the 319 National Highway has a certain slope angle, every time the vehicle reverses out of the vehicle needs a certain amount of braking force, at 1 o'clock in the morning of a certain day, Master Zheng still started as usual - cheer - knock on the tire - check the chassis, everything is ready to work, then start to reverse out.

When stepping on the brakes of two feet, suddenly the brakes became soft, and the feet were empty after stepping on a few feet in a row, at the critical juncture, Master Zheng directly pulled the handbrake, fortunately the vehicle slid for a short time and stopped, the rear wheel was on a stone by the ditch, the moment of danger, when there was a pointed car pulling coal in the same direction of the roadway, fortunately, the other driver changed lanes to avoid.

On this problem, after the car repair came, it was the problem of broken and leaking air in the leather bowl of the brake chamber, which led to the failure of the brake, and it returned to normal after replacement; Here I want to knock on the key point with you, the real name of this "leather bowl" is diaphragm, but we are more accustomed to calling it by its nickname, and then I will introduce to you the overall structure of the brake chamber.

▎Categories and principles of brake chambers

"Which vehicles need to be braked?" Here to answer the question of card friends, according to the national mandatory standard GB7258-2017, all wheels of cars (except for three-wheeled vehicles) and trailers (except for trailers with a total mass of not more than 750kg) must be equipped with brakes, which are also divided into traditional oil brakes and air brakes, and those with brake air chambers belong to the category of air brakes.

Principle: In the process of braking, the truck pushes the diaphragm (leather bowl) in the brake cylinder through compressed air, and then pushes the push rod to rotate the cam at an angle through the adjustment arm, the cam is eccentric, and the brake shoe will be pushed to stretch out to rub the brake drum to form resistance while rotating, and the effect of vehicle braking is played.

Among them, the brakes of trucks are also divided into service brakes, parking brakes and auxiliary brakes, what is the difference between them?

Service brake: service brake is divided into single-cavity brake chamber, double-chamber brake chamber, from the design principle of the vehicle, the braking force of the front wheel needs to be less than the rear wheel, so that there will be no loss of control under emergency braking, so the front wheel responsible for guiding only one service brake cylinder, this kind of cylinder is a single-cavity brake air chamber, only start when driving brake, with the advantages of simple structure, small size, convenient maintenance, etc., you can observe a small bag next to the front wheel.

Parking brake: the general highway trucks are rear-drive, do not exclude four-wheel drive vehicles with climbing needs, such as: pull wood, stones, etc., and responsible for driving, the axle with large carrying capacity will generally use a larger volume, stronger braking force of the double-chamber air chamber, the so-called double-chamber air chamber in the structure is more than a single chamber air chamber, by the internal 2 air chambers, one air chamber is responsible for driving brakes, one air chamber is responsible for parking brakes, can be used for everyone to operate in combination with the actual scene, It is commonly found on drive shafts and trailer axles.

The role of the double-chamber air chamber is really not small, its structure is not complicated, by 2 air interfaces, respectively connected to the driving cavity and the parking cavity, you can see the two small tubes connected above, you have to protect it, this is the airway of the air chamber, can not appear air leakage, and then according to different needs to fill and deflate different cavities to complete the required operation.

Auxiliary braking: the reason why it is called auxiliary braking is to cooperate with the work of the brake chamber, which is generally our common exhaust brake, cylinder brake, hydraulic retarder, and the best effect is the hydraulic retarder, which can complete the effect of replacing the brake water

Knock on the key point: here if you confuse the service brake with the parking brake, it can also be understood that the service brake is "ventilation brake", and the parking brake is "air brake", the name of the air brake is not small, through a strong spring in the brake air chamber, the compressed air will be the spring up when driving, after the handbrake is played, the gas release spring will lock the brake, so the air pressure is too low during the driving process will also produce a braking effect.

Compared with the conventional handbrake, the handbrake is to lock the transmission shaft to achieve parking, some cars are equipped with the structure of mechanical handbrake air brake, there will be a brake air chamber but no air brake, the foot brake is also by the compressed air into the brake chamber to work, but when the handbrake and the transmission shaft fail, the parking brake will fail, and the air brake will fail when any component such as the air pump, pipeline, air reservoir, brake valve fails, the driving brake will fail, and the parking brake will realize stopping to avoid risk.

Many heavy-duty vehicles in the driving brake failure, will be through the indirect loose, tight air brake to achieve the effect of deceleration braking, but do not directly lock the air brake, which will lead to the vehicle out of control, and the indirect loose, tight handbrake can not be too frequent, in principle, so that the operation of the air running is particularly fast, and after the air pressure is vented, it will be invalid, and it can be used as an emergency in an emergency.

▎ What is the failure rate of the brake chamber

As the saying goes: "can drive, will not maintain a car, but also for nothing", so now the car maintenance must not only be able to drive, find the source of goods but also understand the maintenance cycle of the vehicle, the vehicle parts for regular maintenance and replacement, to ensure the stability of the road, but also the primary factor of driving safety, so this set of service brake, parking brake two-in-one dual-chamber air chamber, what are the key points to note?

Under normal circumstances, the failure rate of the single-chamber chamber is very low, and the double-chamber chamber is not so easy to break, usually we have heard of repairing the brake master cylinder, but rarely heard of repairing the brake cylinder, at most only due to the poor quality of the spring, resulting in the brake will not return, the vehicle drags the brake.

But if the energy storage spring in the parking gas chamber is not good, it will lead to a decrease in the parking capacity of the vehicle, resulting in a slip of the locked tire, which is much more serious than the leakage of the handbrake pipeline, the most air leakage is the loss of air pressure resulting in the tire locking and unable to drive, if the diaphragm "leather bowl" is damaged, it will lead to the situation of Master Zheng, the driving brake effect is weakened and the brake fails, and the diaphragm of the double-chamber air chamber is damaged will also lead to incomplete parking brake release, serious tire drag, and even the tread is scrapped.

It should be noted that the energy storage spring in the brake cylinder is to provide braking power for the parking brake, and does not rely on compressed air to complete, so in order to provide sufficient braking power, the energy storage spring in the brake air chamber is very powerful, do not repair the brake cylinder with the energy storage spring, and if you find a problem, you have to wait for professional maintenance personnel to deal with it, so as to avoid personal injury caused by illegal operation.

Usually carefully observe the vehicle leakage, if the vehicle has just stopped, half a day less than the gas leakage of the gas tank, then there is a serious gas leakage problem, you need to go to the car repair shop to carefully check the gas path, do not be careless, at the same time in the dead of night, you can also listen to the "sound" of the vehicle, gas leakage is a slight "hiss" sound, as a professional truck driver, the sense of hearing is much more sensitive than ordinary people.

All in all, the failure rate of the brake chamber is not high, but it can not be bad, the so-called pull a hair and move the whole body, once the brake chamber fails, then it is a fatal problem, now the standard transport in the operating conditions, high-speed road conditions are the majority, so the frequency of stepping on the brakes is also less, it is recommended to try to step on the two-foot brakes before going downhill, if there is a problem, you can reduce the gear in advance to make a deceleration action.