The Study On Dynamic Effect Of Polygonal Wheel On Gear Transmission System Of A Locomotive

As the huge demand of heavy haul railways in the world,a corresponding solution which developing the freight trains with longer length,larger axle load,higher speed has been proposed.High power locomotive will be a trend to develop heavy haul railway transport.Locomotive is usually powered by electromagnetic torque which is transmitted from traction motor to wheelset by gear transmissions,so there is a worse environment for gears and other critical components and some fault will be induced.Meanwhile,with the increase of running distance,contact fatigue and wear phenomenon will become apparent gradually.For instance,polygonal of wheelset is a serious problem of locomotive,which means that gear transmission system will not only be affected by the periodic meshing excitation of the gears,but also influenced by the other periodic excitation from wheel and rail interface and it is subjected to more severe dynamic loading,so fatigue failure and some fault will occur in this system,which will threat running safety of the heavy haul trains.Thus,it will be of guiding significance to make reasonable train maintenance strategies and guarantee the safety of heavy haul trains by studying dynamic effect of polygonal phenomenon on locomotive and gear transmissions and revealing the influence of polygonal orders and depths on dynamic performance of the gears.Firstly,the torsional vibration model of a pair of gears is established.On the basis of the moved Marker technique and output mesh stiffness,the multi-body dynamics model SIMPACK is employed to develop a gear pair multi-body model.Then,this model is input as a subsystem of the locomotive bogie.A whole spacitial locomotive model considering gear transmissions is developed based on the structure and design parameters.By simulation,the vertical dynamic responses of drive‘s cab,bogie,axle box and so on can be acquired.Comparing with the tested vibration results,the established locomotive dynamics model is validated.Then,a traditional locomotive dynamic model is built with the same parameters mentioned before,but this model does not take gear transmissions into account.By comparing the accelerations of drive‘s cab,bogie,axle box and motor form those two models in the same running conditions,the results indicate that the gear transmissions have negligible effects on the lateral vibrations of the locomotive,and it has a significant effect on the vertical and longitudinal vibrations of motor and the wheelset.Thus,it is suggested to consider the dynamic effects of the gear transmissions in the locomotive when analyzing the dynamic characteristics of gear transmissions.Finally,polygonal wheelset is considered as a kind of harmonic excitation and then it is input the established dynamic locomotive model with gear transmissions.Then,when the running speed is 60?80?100?120km/h,dynamic vibrations of the pinion and the gear are analyzed.The results indicate that when the locomotive is running in low speeds,the 5th,6th,7th polygonal orders have a significant influence on vibrations of the gear system.High orders of polygonal wheelset have a larger effect on dynamic characteristics when the locomotive speed is high.In the frequency domain analysis of the transmission system,the high order polygonal wheelset have a significant modulation effect on the meshing frequency of the gears.Under the same polygonal order and the running speed is 60km/h,the vibrations of gears show an upward trend as the polygonal depth increase.