| The problem of front wheel shimmy of automobile with dependent suspension is presented in this paper, in order to study the mechanism and the control technique of the shimmy when brakes are applied. This research bases on the vibration of the steering system and the model of the front wheel shimmy. With the brake-force as an influencing factor, the model is constructed for the study of shimmy when the vehicle runs by beeline. Considering different factors on the brake-force, we analyze the influence of the drum brake and establish the force subsystem which can be applied in different state of the brake. Utilizing the MATLAB/Simulink software, the simulation calculation studies of forced shimmy are completed. The simulation results show that sensitive factors on shimmy. According to the results, a series of tests are completed on the testing vehicle.The results of simulation and tests show that the periodical variety of brake-force is the main factor of the braking shimmy. It is the factor of the variety that the brake drums badly contact with the brake shoes. According to the radial circle run-out tests of different states on the brake, the interference between the brake drum and the rim results in the transfiguration of the brake drum, and augments the radial circle run-out. As is the main factor of the bad contact. What's more, the validity of the model is approved by the tests, and directs the tests. Analyzing the results of simulation and tests, we must decrease the radial circle run-out. As can enhance the stability of the brake efficiency, and mitigate the shimmy when the brakes are applied.This paper showes the main factor of the brake shimmy of vehicles. This will provide a theoretical basis and a practical guidance for avoiding the phenomenon of the brake shimmy, and improve the comfort and the handling-stability. It also acts an important part on reducing the traffic-accident. So there are very important practical sense and value in the studies.
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