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2026
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Data Speaks: Brake Failure Analysis and Solutions
Braking performance is closely related to the overall safety of a vehicle, especially for trucks carrying heavy loads. Previously, Truck Home had a report on the Tianlong 'single pipe' issue, which attracted significant attention because it concerns the vehicle's braking safety.
Recently, a Tianlong 6X4 tractor reported unsatisfactory braking performance. Forum member 'Yonghong' measured the braking data using professional methods and conducted a comprehensive maintenance diagnosis of the vehicle's braking system. By comparing the differences in test data before and after, it further confirmed the previous discussions about the safety hazards of the 'single pipe.'
Now let's take a look at how the forum member solved the issue. Truck owners facing similar problems can refer to the following solution.
Recently, there is a four-year-old 6x4 (dual-drive) Tianlong truck, and the braking performance has never been ideal. The foot pedal of the master cylinder feels heavy; when lightly pressed with an empty load, there is no response, but pressing harder causes the wheels to drag. When heavily loaded, lightly pressing the pedal still provides some braking effect, but pressing further feels like there is no brake at all.
Original car single pipe
Trailer valve replaced from the original car
Load-sensing valve of the original vehicle drive axle
The three-axle synchronous emergency relay valve originally used on the trailer
In order to completely resolve the braking issue of this vehicle, first use a computer to inspect the entire vehicle's braking system.
Test sensor
Test connector
Data acquisition box
First, let's introduce the installation locations and uses of the sensors.
Install the test sensors on trailer valve ports 41 and 42 to test the brake curve output from the upper chamber port 21 and lower chamber port 22 of the main valve during braking.
The drive wheel brake secondary chamber brake chamber is equipped with a sensor to test the brake curve output by the drive axle load-sensing valve when braking (port 2 of the relay valve).
The yellow spiral tube is connected to the sensor, testing the curve when the trailer valve 22 ports are braking.
The red spiral tube is connected to the sensor, testing the curve of how the tractor cylinder supplies air to the trailer cylinder through ports 1 and 11 of the trailer valve (port 1 of the trailer valve).
Install the sensor on the four ports of the emergency relay valve (four ports of the emergency valve) to test the brake curve input of the emergency valve.
A sensor is installed in the trailer brake sub-chamber to test the brake curve of the output from port 2 of the emergency valve.
The trailer air cylinder is usually equipped with sensors at common air points in the dual-circuit brake chambers of the trailer to test the pressure and changes in the trailer air cylinder (trailer air cylinder pressure).
Brake curve test results of the original vehicle braking system
The above images indicate that the red text is the labeling of each curve on the test interface. During the test, first bring the air pressure to the dryer exhaust, then press the brake pedal all the way down, several times in a row.
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