Possibility of increasing the critical speed of high-speed electric trains using transverse cushioning of tractive motors

Introduction. Most modern bullet and high-speed electric trains are equipped with a Class II power actuator with stiff or elastic support of electric motors on the bogie frame. Both tractive motors on the bogies of electric trains of the Velaro platform and on the Sapsan High-Speed Electric Train are rigidly supported on the underpan, which is elastically connected to the bogie frame in the transverse direction by means of four leaf springs. Due to the low lateral stiffness of the suspension, when the train is moving, the underpan with the electric tractive motor makes transverse displacement relative to the bogie frame depending on the amount of free play of the underpan. This design acts as a dynamic shock absorber in a certain frequency range and contributes to an increase in the critical speed of the train.

Materials and methods. In order to evaluate the properties of the electric tractive motor transverse cushioning, the bogie frame was subjected to an amplitude-frequency analysis and a study of free and forced horizontal oscillations of the elastic and stiff suspension systems of the electric tractive motor on the bogie frame with the definition of probabilistic characteristics of random processes. For these purposes, a 3D simulation model of a motor car of a high-speed electric train has been developed in the Universal Mechanism software package. Numerical simulations gave realisations of stationary and ergodic random processes.

Results. The transverse cushioning of the electric tractive motor gives it the function of a dynamic shock absorber, has a positive impact on the stability of the cab at high speed, significantly reduces the amplitude and frequency of horizontal oscillations of the bogie frame, as well as frame forces. The maximum effect of dynamic damping is achieved at a natural frequency of transverse oscillations of the electric tractive motor, close to the frequency of transverse oscillations of the wheel pair.

Discussion and conclusion. The dynamic damping effect can be obtained within a certain range of the natural frequency of transverse oscillations of the electric tractive motor, depending on the parameters of the contact between the wheel and the rail, damping of the horizontal oscillations of the electric motor necessary to limit the resonant oscillation amplitudes. At the same time, the low stiffness of the suspension contributes to an increase in the transverse and angular displacement of the electric tractive motor. Permissible transverse and angular displacement require regulation depending on the characteristics of the gear clutch and the parameters of the undercarriage as a whole at the design stage of this design.

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