Refinement of the rail–wheel contact pair to improve rail–wheel interaction conditions for railway vehicles with an increased axle load

At present, one of the global trends in railway transport development, which becomes clearer and clearer, is increasing the axle load of freight cars, which gives a considerable economic benefit. In this connection, of importance is not only the car design, but also the car capacity utilization factor: the higher this factor, the more economically efficient the car use. Because of this, one of the priority global lines in increasing the volume of fright traffic and the railway operation efficiency is increasing the carrying capacity of freight cars. Preparing the railways for cars with increased axle loads calls for the development of measures to decrease the track deformability, in particular by choosing appropriate wheel and rail profiles. The aim of this work was to develop recommendations on refining the wheel?rail contact pair to improve curve negotiation by railway vehicles with an increased axle loads on the Ukrainian railways. This paper presents the proprietary R-ITM wear-resistant railhead profile. The effect of the new profile on wheel?rail interaction in negotiating a curve of radius 300 m at a constant speed was studied for different cars. In doing so, emphasis was on wheel?rail interaction for a new-generation freight car on 18-9817 trucks with an axle load increased to 36 tf. The studies conducted made it possible to formulate the following recommendations: to improve curve negotiation by railway vehicles with increased axle loads, reduce the adverse effect on the track and improve traffic safety, new proprietary contact pair profiles are recommended: the ITM-73-03 wheel profile for cars, and the R-ITM railhead profile for outer rails together with the standard R65 railhead profile for inner rails.

Improvement on Curve Negotiation Performance of Suspended Monorail Vehicle Considering Flexible Guideway

This work presents the investigation and improvement on curve negotiation performance of suspended monorail vehicle considering a flexible guideway. First, a spatial train–guideway interaction model of suspended monorail system (SMS) is established based on the secondary development of ANSYS software. Then, the dynamic analysis of the train over the flexible curved guideway is conducted, and the curve negotiation performance of the vehicle and the guideway vibration feature are revealed. Subsequently, several crucial design parameters that significantly influence the curve negotiation performance of the vehicle are found, and their influences on the train–guideway dynamic responses are systematically investigated. Finally, by comprehensively considering the dynamic indexes of the vehicle–guideway system, the optimal ranges of these crucial design parameters are obtained. Results show that decreasing the radial stiffness of guiding tyre can effectively reduce the lateral vibration levels of vehicle and guideway, but it would increase the lateral displacements of the bogie and hanging beam; and the radial stiffness is finally suggested to be around 1[Formula: see text]kN/mm by comprehensively considering all dynamic indexes. Increasing the initial compression displacement of guiding tyre can well limit the lateral displacements of the bogie and the hanging beam, thus enhancing the train running safety; however, it would intensify the vehicle-guideway lateral vibration level; especially, the optimal initial compression displacement of guiding tyre is related to its radial stiffness characteristics. To ensure a good curve negotiation performance of vehicle and guideway vibration level, the stiffness of the anti-roll torsion bar and the initial gradient angle of the installed trapezoid four-link suspended device are suggested to be 1.0[Formula: see text]MNm/rad and 65–[Formula: see text], respectively.