The braking performance is related to the safety performance of the whole vehicle, especially for trucks loaded with heavy goods. Before, the truck home had a report on Tianlong’s “one pipe”, which attracted everyone’s high attention because it is related to the braking safety of the whole vehicle.
Recently, a Tianlong 6×4 tractor responded that the braking effect was not ideal. BBCA card friend “Yonghong” measured the braking data through professional data. At the same time, it carried out comprehensive maintenance diagnosis on the braking system of the whole vehicle, compared the gap between the front and rear test data, and further verified the previous discussion on the potential safety hazard of “one pipe”.
Let’s take a look at how card friends solve the problem. If card friends with similar problems can refer to the solution below.
Recently, there is a four-year-old 6×4 (double drive) Tianlong car, and the braking effect is always not ideal. The master cylinder pedal is heavy, the light pedal does not respond when the car is empty, and the tire is dragged when the pedal is heavy. The braking effect is OK when the pedal is slowly pressed under heavy load. If you press it down, you feel that there is no braking again.
Firstly, the installation position and application of the sensor are introduced.
A test sensor is installed at port 41 of the trailer valve and port 42 of the trailer valve to test the braking curve output when braking at port 21 of the upper chamber and port 22 of the lower chamber of the main valve.
A sensor is installed in the foot brake chamber of the drive wheel brake chamber to test the braking curve output by the load sensing valve of the drive axle when braking (port 2 of the relay valve).
The control air output from the upper and lower chambers of the main valve controls the trailer braking after being converted through the trailer valve. The performance of the trailer valve directly affects the braking coordination of the main vehicle and the trailer. The blue circle marks the air pressure curve output from port 22 of the trailer valve, the black circle marks the braking curve input from port 4 of the emergency relay valve on the trailer, and the black curve is the pressure change display curve of port 1 of the trailer valve.
According to the test results, the pressure of the black curve (1 port of the trailer valve) changes too much instantaneously during braking, which affects the follow-up of the braking curve output from port 22 of the trailer valve and the output curve of the upper chamber of the main valve.
There are two reasons for analysis:
1. Caused by the performance problem of trailer valve itself;
2. Since there are 10 air supply pipes at port 1 of the trailer valve of Tianlong truck, throttling may occur.
Combined with the braking effect of the owner’s response, the trailer valve is replaced with the check valve of WABCO, and a 12 pipe is directly connected from the air cylinder to one port of the trailer valve.
The performance of trailer synchronous emergency relay valve affects the braking effect of trailer.
The black circle indicates the braking curve of the output of the emergency relay valve, and the red arrow shows the delay period of the release of the output air pressure when the control air of the emergency relay valve is released. The braking output curve of the original emergency relay valve rises slowly, and the braking release delay is too long, resulting in tire wear and excessive fuel consumption. Replace the three axle emergency relay valve of the original vehicle with two emergency relay valves.
After replacement, the braking output curve and the delay of braking release have been greatly improved.
Finally, the test results of the whole vehicle braking system after maintenance:
After maintenance, through the actual use of the owner, the braking effect is very satisfactory.
For the problems of slow brake release and fast foot brake release of Tianlong drivers, most of them are caused by a one-way valve at the regular air supply of the handbrake valve. There is a 14 hexagon screw plug on the side of the air distribution valve. Remove the plug and there is a spring and a valve plate inside. It is unnecessary to remove the spring and valve plate. Basically, the problem of slow return of the handbrake can be solved.
Original post address: analysis and solution of braking system of four-year Tianlong car
Special topic: investigation and summary of Tianlong’s “one pipe” brake for half a year