Bench Test Study On Braking Performance Of Heavy Commercial Vehicle Auxiliary Braking System

Since China has made its tremendous development in highway transportation recent years,various kinds of transportation equipment are now applied into the entire transport industry according to their functions,such as heavy-duty commercial vehicles or freight containers.With the continually technology promotion of vehicle capacity and speed,more challenges arouse for vehicle brake on loading issue.The pressure would enhance especially when it's in poor road condition(like mountainous area which accounted for 70% of Chinese land area)which causes frequent braking and worse heat dissipation that probably bring huge potential risk due to braking performance degradation.Therefore,the installation of continuous braking devices is necessary to improve safety for current heavy-duty commercial vehicles.And also the study of auxiliary braking system will ensure the vehicle's downhill ability for long ramps with application data support.On the basis of the research on the principle of the existing main auxiliary brake system for heavy commercial vehicles,a certain type of six axle truck is selected as the research object for the purpose of its continuous braking performance test in the study.The test will reflect braking performances to different downhill grades stimulated by chassis dynamometer,and reach the evaluation on affecting factor and finally the analysis to improve auxiliary brake system.Firstly,a sliding test on level road has been proceeded to vehicle to respectively obtain speed & time data under driving resistance.And in terms of force balance equation,the mathematical model of sliding resistance has been established and revised in order to reach the analysis about the factors that affecting sliding resistance.In addition,detailed data processing has also been carried through vehicle sliding test based on its data reception criteria,which provides the essential basis for numerical simulation loading in vehicle chassis dynamometer designing and testing.Test for vehicle's continuous braking performance is carried out on the chassis dynamometer in the thesis.The simulation test on engine exhaust brake and hydrodynamic retarder in chassis dynamometer-functioning separately or together,reflects the vehicle's different performances on various ramps and come to analysis of related factors effect maximum continuous braking power most.In conclusion,the thesis provides not only support to retarder braking system test,but practical theory and application value for heavy duty commercial vehicle.