Wheel/rail-force–based maintenance interval extension of the C80 series wagon

Purpose–This study aims to introduce the achievements and benefits of applying wheel/rail-force–based maintenance interval extension of the C80 series wagon in China.Design/methodology/approach–Chinese wagons’existing maintenance strategy had left a certain safety margin for the characteristics of widely running range,unstable service environment and submission to transportation organization requirements.To reduce maintenance costs,China railway(CR)has attempted to extend the maintenance interval since 2020.The maintenance cycle of C80 series heavy haul wagons is extended by three months(no stable routing)or 50,000 km(regular routing).However,in the meantime,the alarming rate of the running state,a key index to reflect the severe degree of hunting stability,by the train performance detection system(TPDS)for the C80 series heavy haul wagons has increased significantly.Findings–The present paper addresses a big data statistical way to evaluate the risk of allowing the C80 series heavy haul wagons to remain in operation longer than stipulated by the maintenance interval initial set.Through the maintenance and wayside-detectordata,whichis divided intothreestages,the extension period(three months),the current maintenance period and the previous maintenance period,this method reveals the alarming rate of hunting was correlated with maintenance interval.The maintainability of wagons will be achieved by utilizing wagon performance degradation modeling with the state of the wheelset and the often-contact side bearing.This paper also proposes a statistical model to return to the average safety level of the previous maintenance period’s baseline through correct alarming thresholds for unplanned corrective maintenance.Originality/value–The paper proposes an approach to reduce safety risk due to maintenance interval extension by effective maintenance program.The results are expected to help the railway company make the optimal solution to balance safety and the economy.

Experimental study of the wheel/rail impact caused by wheel flat within 400 km/h using full-scale roller rig

Purpose–In service,the periodic clashes of wheel flat against the rail result in large wheel/rail impact force and high-frequency vibration,leading to severe damage on the wheelset,rail and track structure.This study aims to analyze characteristics and dynamic impact law of wheel and rail caused by wheel flat of high-speed trains.Design/methodology/approach–A full-scale high-speed wheel/rail interface test rig was used for the test of the dynamic impact of wheel/rail caused by wheel flat of high-speed train.With wheel flats of different lengths,widths and depths manually set around the rolling circle of the wheel tread,and wheel/rail dynamic impact tests to the flats in the speed range of 0–400 km/h on the rig were conducted.Findings–As the speed goes up,the flat induced the maximum of the wheel/rail dynamic impact force increases rapidly before it reaches its limit at the speed of around 35 km/h.It then goes down gradually as the speed continues to grow.The impact of flat wheel on rail leads to 100–500 Hz middle-frequency vibration,and around 2,000 Hz and 6,000 Hz high-frequency vibration.In case of any wheel flat found during operation,the train speed shall be controlled according to the status of the flat and avoid the running speed of 20 km/h–80 km/h as much as possible.Originality/value–The research can provide a new method to obtain the dynamic impact of wheel/rail caused by wheel flat by a full-scale high-speed wheel/rail interface test rig.The relations among the flat size,the running speed and the dynamic impact are hopefully of reference to the building of speed limits for HSR wheel flat of different degrees.