Analysis On The Selection Of Brake Shoe And Wheel Of An Engineering Vehicle Based On Multiple Factors

In order to improve the efficiency of railway transportation,the engineering vehicle should improve its own speed under the condition of meeting the operation requirements to arrive at the work place faster for operation.Under this background,a kind of engineering vehicle with the maximum running speed of 160 km/h and the axle load of 21 tons has been developed.The successful design experience of DF₁₁ diesel locomotive with the maximum running speed of 160 km/h is used for reference in the research and development of the engineering vehicle.Under the condition of meeting the UIC standard,the basic braking method is double pads-wheel braking with lower cost and unsprung mass than disc braking.In order to ensure the safety of braking,it is necessary to analyze the selection of tread brake shoes and wheels of the engineering vehicle.Firstly,this thesis analyzed the selection of tread brake shoes and wheels of the engineering vehicle from five aspects:material properties,braking distance limitation,wheel adhesion limitation,ramp parking ability and wheel temperature limitation.The material and type of brake shoes,single and double side braking method of wheels and wheels diameter were determined.Secondly,a three-dimensional finite element model of the wheel was established through the software named Hyper Mesh,and the software named ANSYS was used to solve and post-process.According to the standard of TB/T 3463-2016 Evaluation Method for Wheel Strength of Rolling Stock,the static strength and fatigue strength of the wheel with limited wear（wheel diameter of 845 mm）of the engineering vehicle with M-type powder metallurgy brake shoes,double-sided braking,initial braking speed of 160 km/h and new wheel diameter of 915 mm were analyzed.From the calculation results of the static strength of the wheel,the safety factor of the wheel web is greater than 1 in the straight braking condition and the curved braking condition.In the turnout condition,the safety factor of the different areas of the wheel rim is also greater than 1.According to the calculation results of the fatigue strength of the wheels,the fatigue strength safety factors of the nodes in the verification area are all greater than 1.The calculation results show that the wheels meet the strength requirements.Thirdly,the force of the engineering vehicle on the long heavy down grade of the Xi’an-Chengdu high-speed railway is analyzed,and the basic resistance,the additional resistance of the ramp,the braking force of the tread and the resistance braking force of the vehicle were calculated,and the feasibility of the braking scheme of the engineering vehicle on the long heavy down grade was analyzed.The results show that,when using intermittent or continuous resistance braking throughout the entire process on the long heavy down grade of the Xi’an-Chengdu high-speed railway,the range of the sustainable speed limit is 2 km/h～160 km/h;when using pure tread braking,wheel can meet the requirement that the maximum temperature of the tread is not higher than 400℃.Finally,finite element model with the three-dimensional transient braking thermal load of wheel of the engineering vehicle was established,and the wheel temperature field distribution under different rim wear,axle load,ambient temperature,initial tread temperature and braking pressure was calculated by ANSYS software during emergency braking,and the time needed for the wheel to cool to close to the ambient temperature was obtained.The calculation results show that under the same brake initial speed,the higher the ambient temperature,initial tread temperature,brake cylinder pressure rim wear and axle load,the higher temperature at the moment when the maximum temperature of wheel tread reaches the peak value.The time required for the wheel to cool to close to the ambient temperature has different rules under different working conditions.