Lazy hands and fakes must be subjected to suffocating brake system check points

[Hubei Cheng Li original] winter comes, the temperature plummeted, the truck of the air brake system began to show a typical seasonal failure: not pumping, brake does not return, brake failure to bring everyone no small trouble, and some also lead to serious ACCIDENT. Therefore, it is important to do a comprehensive investigation of the vehicle air brake system before entering the winter. After years of improvements and upgrades in the domestic mainstream truck air brake system, the basic structure has not changed much. However, new components such as ABS sensors and air dryers are more demanding on the braking system, and special attention is required here. .

Through the case investigation of truck drivers and some accidents, some serious accidents, such as the phenomenon of a trailer fire and brake failure, are related to the braking system, and often the minor faults and components eventually cause a disaster. Some failures are caused by the fact that the system does not normally check or use false parts. These parts are very easy to cause illusions. The following points from several aspects to explain the inspection and the usual replacement of several points.

●   Air compressor checking oleophobicity will lead to downstream failure

Usually check the pressure relief valve exhaust port, pay attention to whether the serious oil pollution, serious oil pollution, air compressor maintenance, if necessary, replace.

Pay particular attention to whether the oil pipe of the compressor oil is in good condition. Note that the oil pipe can not be repaired by welding, and there is no any trouble or vibration during installation. The breakage of the lubricant tube can easily lead to serious failure of the air pump and engine. The tubing should be spared for replacement in normal vehicles. Check if the inlet line of the air compressor is in good condition to ensure that the inlet air is clean and sealed. (different types of engine air compressors are different)

During the cold start in winter, when the water temperature does not reach 60-80 degrees, it is forbidden to run the engine with a large throttle, so as to avoid the cylinder compressor and excessive wear due to poor lubrication of the air compressor, resulting in carbon deposition of the olein oil and the cylinder head (air compressor).

●   Dryer check intake air temperature high impact regeneration performance

Dryer from the appearance is difficult to distinguish the performance advantages and disadvantages, because the dryer to complete a work cycle, need to "absorb - drain" two actions. In addition to the selection of high quality dryers, it is necessary to check whether the system works normally, such as serious oil pollution under the exhaust port, indicating that the desiccator molecular sieve is heavily polluted by the oil contamination and has completely failed and does not have the function of water absorption.

Dryer back blowing performance check, the normal operation of the dryer in the pressure relief action, through the blower tank or compressed air in the air cylinder back dryer molecular sieve, discharge water. At this time, the exhaust port has a "click" sound and water vapor exhaust. If there is no exhaust action, check the dryer base, pressure limiting valve, four-circuit protection valve, etc., and replace if necessary.

Checking the temperature of the inlet air can be accomplished through the temperature test paper. When the temperature is higher than 65 degrees, the filter performance of the dryer will decline or even fail. In particular, some batch tractors of Dongfeng Tianlong are required to install spiral coils and other methods to achieve the purpose of cooling.

●   Sensor detects faulty wire ice alarm system failure

Winter snow splashing tires, it is easy to cause freezing of electrical circuit lines, resulting in short circuits and pull open circuit. Should be wrapped in cling film on the line, a small amount of grease or lubricating oil to prevent water condensation.

The air reservoir pressure sensor and the ABS solenoid valve are also wrapped in plastic wrap to prevent signal failure and false alarms due to ice formation. This is a common technique used by bus drivers in the North.

●   Gas line inspection pays special attention to active gas line breaks

“Activated” air piping refers to a type of trachea where movement occurs, such as brake cylinders connected to the air pipes at both ends of the frame, and trailers to the spiral tubes of the main vehicle. This type of tracheal material is special, long-term exercise is prone to fatigue, cracks and even fracture.

“Activity” gas pipelines cannot be replaced by hydraulic pressure oil hoses. This is due to the fact that the hydraulic oil hoses have a steel wire lining and the bending deformation has a certain range. For example, the front and rear bridge pump pipes have large telescopic movements, and the mixed hydraulic hoses can easily crack inside. The high-quality trachea should be a rubber-made trachea, with a steel wire protective layer on the outside, and a ply reinforcement layer on the outside. The outer steel wire layer disperses the external deformation forces and prevents scraping and interference.

Trailer trachea pays special attention to the interface parts, especially the "sub-tubes" of poor quality PVC materials, are often mixed, and the low temperature performance is extremely brittle and easy to break and break.

Poor sub-pipes are installed between sub-pumps and emergency relay valves. If the leakage phenomenon is not detected in time, it will cause brake failure. In particular, the leakage of the parking brake pipe line, the spring action makes the brake bite, resulting in brake hub overheating, according to statistics, 70% of the semi-trailer fire is caused by the gas circuit failure, this is not alarmist.

Pay special attention to whether there is any air leakage in the airway interface of the sub-pump or not. Check the parking brake pipe should be released under the braking condition. Do a good job of anti-sliding measures for the vehicle. Under the safe conditions, check each one by one, and do not cause air leakage. Bad brake return causes the brake hub to overheat and cause a fire.

●   Brake return check attention to active return and passive return

1 Active return part
 
Brake return action is divided into active and passive return, passive return specifically refers to the brake hub inner shoe return spring, shoe fixing pin and other institutions. The active return action is affected by multiple components. Firstly, the compressed air is sufficient, the brake pedal is depressed, and the pedal is rapidly released. Observe the exhaust condition of the relay valve or quick release valve. If the air release is slow, repair it in time. replace. Most valve body damage is related to oil and water, check the dryer.

Brake cylinder return spring attention to check whether the broken or material fatigue, do not underestimate this little spring, according to the lever principle, the return spring force will be greater than the passive spring pull shoe role. If necessary, replace the high-strength return spring to improve the reaction time and reliable return of the braking action. In addition, the small spring guarantees a good brake return, which will save more fuel and completely improve the brake bite.

2 passive return part

The passive return part refers to various parts in the brake hub. The return spring of the shoe needs to be checked up and down with a crowbar. If there is no elasticity and fatigue, it needs to be replaced in time. In order to prevent the lower shoe from returning poorly for a long period of time, there is interference with the brake hub, resulting in high temperature, and the brake gap clearance appears to have astringent illusions that cannot be properly adjusted.

Brake drum camshaft and brake shoe fixing pin need to pay attention to whether the activity is easy, such as hair astringent need to remove the grinding rust treatment, if necessary, replace. Excessive activity requires replacement of brake shoe bushings or assemblies.

●   Brake disc hub check brake brake king pay attention to brake hub life

Many truck users like to use the "Brake King". Such violations increase the brake pressure as if it were a thirst. Often overlooked the advantages and disadvantages of the brakes will affect the braking performance. For example, a fake BPW axle brake pad can not reach 40% of the friction of the original tablet, the brakes are overheated and the brake hub is scrapped in advance.

The riveting of the brake pads requires special equipment, which is manually riveted or bolted, and is easy to loosen. Note that the use of the brake king is prone to serious accidents such as breakage and loosening of the brake pads. This is the main reason for the brake hub's fire, and it is often overlooked.

The brake hub is used for a long time and the edges will “worse”. It is a normal phenomenon. There is no crack in the main body of the brake hub, and the internal part is smooth. It can be repaired and used normally within 3mm. The extra convex grooves are leveled with a grinder, and the thicker brake pads can be used continuously to save the economic cost.

Note that vehicles equipped with "Brake King" cannot be used. This is due to the uneven braking force, which causes unevenness of the inner surface of the hub, cracking of the brake pads and hub, and cracking.

After the inner diameter of the brake hub becomes larger, the brake force is restored by changing the method of “increasing the camshaft on the camshaft”. It should be noted that after replacing the enlarged wheel, the curve of the braking action also changes, and the phenomenon of poor returning is likely to occur. In particular, after the brake pad clearance is too large, it is usually necessary to adjust the brake clearance in a timely manner. At this time, the passive return spring action of the shoe is limited, and the return spring of the sub-pump needs to be strengthened.

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