Abstract: The safety system of rubber-tyred vehicles is designed. The mechanics model is established in the brake disc and the buffer, the factors about influencing the change of braking force are analyzed, the tension change about wire rope is analyzed, and the reference to the peak of the acceleration is proposed, the change of the braking force of the buffer and brake disc is analyzed by ADAMS simulation. The simulation results and experimental data and theory analysis are compared. The results show that the system will give variable braking force according to different running conditions of the transportation vehicle. To expand the application range of the system, increasing its practicability, the driver will feel comfortable and achieve the flexible buffer.