The Influence And The Optimizing Analysis Of Braking Characteristics On The Longitude Impulse

With the development of railway transportation in the world, the heavy haul technology is attracted more and more attention. Countries opened heavy haul freight train in succession, also met with various of technical problems, especially the problem of large longitudinal impulse. Several research organizations explore and research the methods to solve these problems constantly. China is a great power of railway transportation. Railway bears the heavy transport tasks, as the main artery of the national economy. It is also our country’s current direction of development to improve the technology of heavy haul freight train. At the same time, there are more requirements in train braking system performance and driving safety of train, with the developments of the marshalling of train and trailing load.The longitudinal impulse will cause certain damage to the vehicle structure in transit, at the same time, it will also affect the quality and safety of the train operation. The longitudinal impulse is influenced by various factors. Among others, the braking system is the essential part of the entire train and the main factor to affect the longitudinal impulse, which relates to the train’s stability and security in transit. Therefore, train braking system is the emphasis that need to be addressed.It is the major reason of longitudinal impulse in braking that the braking action is asynchronism and nonuniform along the length of the train. The earlier research on train longitudinal dynamics suggestes that the longitudinal impact is closely related to braking characteristic. It is possible that the coupler force is decreased by changing the braking characteristic. Using the brake system simulation software, in the case of full service application, the influence law of the pressure increasing speed of brake cylinder to the longitudinal impulse is studied, as the1000tons train for the research object. Under the condition of same stopping distance of train, the pressure increasing speed of brake cylinder of front and rear vehicles are changed. The pressure increasing speed of front vehicle is reduced and the rear vehicle’s is opposite. And more reasonable braking characteristic is got by comparison.The result shows that the sum of the brake cylinder pressures of entire train is the main factor to influence the braking distance. In brake system designing, to ensure lower train coupler force, braking capability difference between the front and the rear of train should be as small as possible. Braking capability difference of between the front and the rear of train could be reduced by optimizing braking characteristic. In the result of optimal scheme, the maximum compressive hook reduces by34.82%, and the maximum pull hook reduces by35.29%. In this paper, the calculation by the simulation software is great important to improve economy, security of the train and heavy haul transportation technology.