Research On Braking Capacity Of Heavy Haul Train On Daqin Line

With the national economic growth and railway development,the operation of heavy haul train is one of the directions to solve the problem of railway freight transportation.The technology of heavy-load freight trains in China started late and developed rapidly.The Daqing-Qinhuangdao Railway is the first heavy-load line in China.Since 2008,20000 tons of heavy-load combined trains have been operated normally,and the operation test of 30000 tons of heavy-load combined trains has been completed in 2014.The following heavy-load lines opened in China include Shuohuang Line,Wari Line and Haoji Line.The corresponding heavy-load braking technology has also been rapidly developed while the heavy haul train are running.The braking technologies that have been used on heavy haul train include Locotrol control technology,controllable train tail technology and 120-1 control valve with common acceleration braking function.The adoption of these technologies provides a strong guarantee for the smooth operation of heavy haul train.The main research object of this paper is the Daqin heavy haul coal transportation special line.The problems that affect the braking force of the heavy haul train on the Daqin line are as follows: First,there is a large difference between the actual decompression amount of the train pipe and the locomotive operation decompression amount;The second is that the pressure reduction of train pipe,the piston stroke of brake cylinder,the performance of 120-1 valve,and the failure of brake accessories affect the braking capacity of the train;The third is that the amount of pressure reduction during the speed regulation braking of the 20000 t heavy haul train cannot be adjusted according to the line conditions of the braking section,which leads to the need for additional pressure reduction or adjustment of the locomotive electric braking force for the heavy haul train.Combined with the factors affecting the train braking force,the main research contents are as follows: first,the research on the change law of equalizing air cylinder pressure,train pipe pressure and train pipe pressure reduction before braking;The second is the research on the change law of vehicle brake cylinder pressure and vehicle pipe pressure reduction,brake cylinder piston stroke,120-1 valve performance,brake accessory failure,etc;The third is the research on the change law of pressure reduction of train pipe and the resistance of train brake shoe;The fourth is the research on the change rule of brake shoe resistance in different railway line sections and train sets;The fifth is the research on the change rule of train pipe pressure reduction due to the speed change of 20000 t heavy-load train in different railway line sections.It mainly adopts comprehensive analysis of vehicle braking accessories,vehicle braking system and locomotive braking system,and innovatively analyzes the change of brake shoe resistance of the train set at the initial,intermediate and final stages of the braking process to infer whether there is abnormal braking performance of the train set;Through calculation and monitoring,the resistance of train brake shoe when the train is running in different sections can be obtained,and the demand of train pipe pressure reduction when the train is running in different railway line sections can be judged.It is proposed how to accurately control the pressure reduction of the train pipe of the heavy-load train and how to accurately reduce the pressure according to the operation section of the 20000 t heavy-load train,and finally achieve the purpose of accurately controlling the train operation speed.Finally,based on the development needs of heavy haul train,the necessity of adopting electro-pneumatic braking for heavy haul train is proposed.