How to maintain the braking system of a flatbed semi-trailer?

In heavy-load transportation scenarios, the reliability of the braking system of flatbed semi-trailers is directly related to road safety. According to statistics, traffic accidents caused by brake system failures account for 32%, among which brake failures due to improper maintenance make up 68%. This article will analyze the scientific maintenance methods for the braking system of flatbed semi-trailers from three dimensions: system inspection, component replacement, and operation norms.

I. Brake Fluid Management: Quality Control of Core Medium

Brake fluid, as an energy transmission medium, its performance directly affects the braking response. The boiling point of DOT4 brake fluid should be above 230℃. When the water content exceeds 3%, it needs to be replaced immediately. In the humid southern regions, it is recommended to replace it every 20,000 kilometers or once a year. In the dry northern regions, the replacement can be extended to 40,000 kilometers or once every two years. When replacing, dedicated equipment must be used to completely expel the air in the system. A certain logistics company once caused a braking delay of 0.8 seconds due to incomplete exhaust, resulting in a rear-end collision.

Daily inspections require monthly liquid level measurement, and the liquid level should be within the range of MAX to MIN marks. If the liquid level drops by more than 10%, it is necessary to check whether the pipeline joints are leaking. A certain fleet has reduced the average time for detecting brake fluid leakage from 72 hours to 2 hours by installing liquid level sensors, resulting in an annual loss reduction of over 500,000 yuan.

Ii. Maintenance of Friction Components: Periodic Management of Wear Parts

Brake pads must be replaced when their thickness is less than 3mm. Front wheel brake pads are usually replaced every 60,000 kilometers, while rear wheels, which bear a greater load, need to be inspected every 40,000 kilometers. A certain transportation enterprise adopted a laser thickness gauge for non-destructive testing, which reduced the unplanned replacement rate by 40%. When the brake disc has grooves or cracks exceeding 1.5mm, disc treatment is required. If the cumulative disc quantity exceeds 2mm, the entire disc should be replaced.

When the inner diameter of the brake drum wears more than 3mm or cracks appear, it must be replaced. A certain mine transportation fleet has reduced the accident rate of brake drum cracking caused by overheating from 2.3 times per month to 0.1 times by installing temperature sensors. When cleaning the accumulated dust inside the brake drum, a dedicated vacuum cleaner should be used to prevent the inhalation of asbestos dust.

Iii. Maintenance of Airway System: Precise Regulation of Pressure Control

The pressure in the air brake system's air storage tank should be maintained at 0.8-1.0MPa. When the air pressure drops below 0.6MPa, the braking efficiency decreases by 40%. Before each departure, the working condition of the drying tank needs to be checked. A certain fleet has reduced the moisture content in the airway from 5% to 0.3% by installing an electronic desiccant regeneration device, and the occurrence of brake valve freezing faults has decreased by 90%.

The sensor clearance of the ABS system should be maintained at 0.5-1.5mm. If the wear of the tooth height of the gear ring exceeds 1mm, it needs to be replaced. In winter, the water in the air storage tank needs to be drained every three days. After a certain northern fleet adopted an automatic drain valve, the brake failure accidents caused by air line icing were completely eliminated. The relay valve piston needs to be coated with special grease every year to prevent jamming at low temperatures.

Iv. Operating Specifications: Braking Protection Based on Driving Habits

When going down a long slope, engine braking combined with intermittent braking should be adopted. Tests on a certain mountainous section of the road show that continuous braking for 20 minutes can raise the temperature of the brake pads to 600℃, while engine braking can keep the temperature within 200℃. The braking distance on a slippery road is three times that on a dry road, and deceleration should start 50 meters in advance.

A certain dangerous goods transportation company has reduced the frequency of emergency braking from 12 times a month to 3 times through driver training, decreased the tire wear rate by 35%, and lowered the maintenance cost of the braking system by 28%. It is recommended to install a braking pressure monitoring system to display the distribution of braking force between the front and rear axles in real time.

At present, intelligent braking systems are becoming a development trend. The EBS electronic braking system equipped on a certain brand of semi-trailer can reduce the braking response time from 0.3 seconds to 0.15 seconds, and at the same time, through pressure regulation, the braking force matching accuracy of each axle can reach 98%. In the future, with the popularization of by-wire braking technology, the braking safety of flatbed semi-trailers will witness a qualitative leap.