Research On Detection Method Of Braking Sequence Of Truck’s Air Brake System

In our country, along with the development of economy, automobile transportationrequires improving vehicle carrying capacity continuously, but ordinary car axle loadsand contour dimension are limited by road regulations, so the carrying capacitycannot be too much too large. So trailer automobile train came into being.The braking stability of the car train is directly related to the safety of the vehicle,and the braking time sequence in braking process is directly related to the brakingstability and safety. Both theoretical analysis and practical use results show that thetractor will be subject to great impact of trailer, when the tractor rear axle or tractionvehicle front and rear shafts brake before the trailer axles. The braking stability oftrailer automobile train with fixed braking force distribution can be improved whenthe braking sequence meet certain requirements. The existing roller brake test stationand plate brake testing bench can only detect braking force size of trailer automobiletrain. But these testing station cannot detect the air braking sequence. Therefore it isnecessary to study an accurate and fast method and tool to detect the air brakingsequence.The air brake sequence detection method of the truck studied in this paper, we firstcollected the displacement change of brake pushrod during braking while the enginewas in starting and the stalling of the two states, then filtered test data of starting upby using MATLAB. We found that the filtered displacement curve was very similarwith the extinction curves, but acceleration signal interference of flameout state wassmall. Then we studied the acceleration signal changes, in the different locations(brake chamber, brake pushrod, etc.) and different directions (x, y, z) of the brakingsystem in the braking process. From the data we saw that the acceleration signal alongthe direction of movement of the push rod of changed significantly and was similarwith the displacement of the variation and brake push rod along the push rod movingin the direction. In the process of testing, the installation of displacement sensor fordifferent models need to install different bracket, resulted in installation difficulties,and time-consuming, which was not suitable for rapid detection. The accelerationsensor used strong magnetic suction in the detection position, which made it easy and fast to install..Based on the research of the braking sequence detection of the air brake system, theacceleration in the direction of the push rod moving was chosen to detect the brakingsequence. In order to verify the reliability of the test method, we carried out a lot ofreal car tests, and the test results proved the feasibility of our testing method. Thesequence of the air pressure braking can be detected accurately by using the timesequence detection method, which can ensure the stability of the pneumatic brake andreduce the occurrence of traffic accidents.