Research On Transmission Efficiency And Brake Shoe Eccentric Wear Of Railway Wagon Foundation Brake Rigging

With the development of railway wagon heavy haul,newly built general wagon has been upgraded from 60t level to 70t level.The application of 70t level railway wagon greatly improves transportation capacity of railway wagon,but it is found that there are phenomena of low transmission efficiency and brake shoe eccentric wear of foundation brake rigging.Both will lead to longer braking distance and further threaten safety of railway wagon.In view of these problems,the field test observation is more difficult and its cost is high.So this paper uses analytic method to find out the root of these problems.The analytical method is more simplified than the field test in the model and can not reflect the contact and collision between the parts of such mechanism with clearance,so multi-body dynamic simulation is used.The virtual experiment is done by simulation technology,and the analytical method results is supplemented and corrected.The main research contents and results include:Firstly,the structure and braking principle of foundation brake rigging are analyzed,and the theoretical value of the brake shoe pressure is solved by analytic method,then the transmission efficiency is calculated and the cause of low transmission efficiency is analyzed.The results show that theoretical values of transmission efficiency of the empty and load are 0.569 and 0.710.Main factors of the transmission efficiency loss are friction resistance of the connecting parts of bogie,relieving spring resistance of brake cylinder and its internal friction resistance.Secondly,the change of brake shoe position and posture is analyzed,the brake shoe instantaneous force model is abstracted,the relationship between the ratio of upper lower end pressure and the upper lower end wear is solved by analytic method.,the mechanism of eccentric wear is analyzed and the suggestion of prolonging life is put forward.The results show that the direction of the braking force and the dip angle of the sliding groove lead to the initial eccentric wear,then causes a larger wear of middle stage and a serious eccentric wear in the end.It is recommended that the upper and lower ends of the brake shoe be adjusted to install when the end of the brake shoe reaches 16mm,so as to extend the service life.Finally,the modeling of the foundation brake rigging and the simulation experiment of transmission efficiency and brake shoe eccentric wear are carried out by RecurDyn.Transmission efficiency simulation show that the simulation result is consistent with the analytical result,but its eficiency is higher.The reason is that when the friction force is calculated by the analytical method,it is assumed that the splint is double faced with the lever,while mostly unilateral contact in simulation.Eccentric wear simulation show that the simulation result is consistent with the analytical result,but its degree is lower.The reason is that the pressure is equivalent to the upper lower ends in analytical method,while acts on the whole surface in simulation.To sum up,the simulation results verify the trend of the analytical method,and the simulation experiments complement and correct the result of the analytical method.Above research results provide theoretical and technical support for low transmission efficiency and eccentric wear research.The method of combining analytical with multi-body dynamics simulation is of universal significance for the study of contact and collision problems of clearance mechanisms such as foundation brake rigging.