For improving braking efficiency, the high friction composite brake shoe, instead of cast-iron shoe, is widely used in railway wagon. However, some flange and tread of the foundation brake rigging wear frequently in operation, leading to the over standard of wheel diameter difference, which affects the safety performance and the running efficiency of railway transport. This paper uses the normal pressure between wheels and shoes as the evaluation index of tread wear and the lateral shift of brake beam as the evaluation index of flange wear. With the multi-body dynamics simulation method, take a research on the influence of curve braking for flange and tread wear. Firstly, establish a multi-rigid body dynamics model of the foundation brake rigging in RecurDyn software. And then, take a research on the lateral shift of brake beam and the pressure distribution of shoes for empty and loaded wagon on four kinds of curves braking respectively. At last, to testify the simulation results theoretically, analytical method is used to derive lateral force of the brake beam. The results indicate that the lateral shift of rear brake beam which lead the shoe moving close to the flange is the cause of flange wear, and the positive pressure between wheel and shoe of one wheel-order bigger than others is the cause of tread wear. The research accomplishments above provide technical support for further improvement of the foundation brake rigging in railway wagons.

In this paper, a theoretical mechanical model for the brake shoe is set up according to the foundation brake unit of railway freight cars, and it indicates that the friction moment is the origin resulting in brake shoe eccentric wear. On this basis, the pressure distribution formula on the brake shoe is derived when the train brakes in forward and backward direction respectively. The analysis results show that if the wheel and the brake shoe are concentric, the ratio of the revolving-in end pressure to the revolving-out end pressure in wheel forward revolving is larger than that in wheel backward revolving. It is consistent with the phenomena that upper eccentric wear often appears on the brake shoe in practice. Further research reveals that the degree of the eccentric wear is determined by the braking force action style, which is the theoretical basis for the design revision. In addition, the RecurDyn Multi-body Dynamics software is used to build the rigid-flexible coupling dynamics model for the foundation brake unit. The simulation experiment verified the analysis result. The research outcome provides the theoretical basis and technical support for further design improvement of the foundation brake unit in railway freight cars.

The safety and reliability of railway vehicle braking system is put forward higher requirement for railway speed increasing. Compared with domestic product, foreign disc brake unit has obvious advantage on compactness of structure, stability of braking pad friction coefficient, braking power, safety and reliability etc. Thus, the research has theoretical significance and engineering value. Firstly, the working principle of disc brake unit is obtained by performing spatial mechanisms analysis of some imported disc brake unit and adjuster structure, then using MBD (Multi-body Dynamics) simulation software, by importing the geometric model of brake unit into RecurDyn, to make preprocess of simplifying and merging and add constraints and contact relation, driving control functions, etc, finally to establish a simulation experiment model. The working characteristic of the brake unit and adjuster's displacement curve of clearance compensation is obtained through the braking and releasing simulation results of braking pad before and after wear out. The research results provide a method based on virtual prototype for analyzing and validating working mechanism of disc brake unit.