:Axle box bearing is an important core department of the train running parts, but it becomes one of the vulnerable parts , because of its bad load condition. It is of great significance for bearing life prediction based on load distribution and ensuring its safety and reliability by studying the load characteristics between roller raceways in operation. Based on the dynamic model of vehicle-track dynamic model with bearings, the contact load characteristics of roller raceway under track excitation and train running speed are studied. The results show that under the condition of no excitation, the speed has little effect on the contact load of the roller raceway, but in the non-bearing area, the roller will contact with the outer raceway, and the contact load is square with the speed. The track excitation condition will affect the instantaneous value of contact load of roller raceway. The standard deviation of the contact load on the outer ring increases with the speed of the vehicle. By studying the maximum contact load on the outer ring, it is found that with the increase of speed, the greater the vibration caused by track excitation, the greater the fluctuation of contact load data of roller raceway.
:The structural reliability of brake disc bolts of the high speed EMU is important for operation safety. Based on the load test of brake disc bolts of the high speed EMU, there is a five days' test on a certain type of EMU, with the total test mileage of 6 546 km. Under normal working conditions and failure conditions, dynamic characteristics of bolt load of brake discs are obtained, and the fatigue strength assessment under different operation conditions is completed. The characteristics of bolt structure are combined with the test data. The samples of electrical braking, continuous air braking and emergency braking are analyzed, and its operational reliability is estimated. It is shown that the load of the brake discs of the power axle is not obviously changed under normal conditions. Under failure conditions, the load of the brake discs of the power axle is obviously increased. With the increase of air braking, a rise in the temperature of brake discs and bolts is resulted by the fiction heat. Because of the differences of the materials and structures, there are different deformations of brake discs and bolts, which lead to a great change of bolt stress.
:Wheel/rail force is the basis of the wheel rail relationship study, and it is the most important index to determine the vehicle operation safety. Furthermore, wheel/rail forces continuously measuring method is one of the complicate problems needed to be investigated, and it is the primary strategy to study on the vehicle system dynamics. Based on the relationship between the loads and strain of the wheels and axle, a continuous wheel/rail force measuring method is presented after strain gauges signal output derivation and wheel finite element calculation. The method includes the number and location of the strain gauges on the wheel rims and axle.Test bridges of the strain gauges are offered to get the signals of the strains. A 1∶5 scale force measuring wheelset is manufactured.The stain gauges are fixed on the scaled wheelset and the test bridges are developed according to method presented Wheel/rail lateral and vertical force are calibrated, and the relationship matrix between the loads and the strains are obtained. The methods, such as optimal location of strain gauges, numerical regression of calibration data and strain gauges joint application of wheels and axle, are introduced to minimize the error. An experiment is carried out to measure the wheel/rail forces with the scaled wheelset and a 1∶5 scale roller rig. The test results show that the wheel/rail force continuously measuring method is effective and accurate to obtain the wheel/rail loads.
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