Purpose: To develop an improved model of inter-car coupling equipped with spring-friction absorbing devices of the PMK-110 type. This model should take into account both the features of the power characteristics of absorbing devices of this type and the deformation of the carriage bodies, as well as the energy dissipation of longitudinal forces arising in the train due to the viscous resistance to deformation of the car structure. Methods: Methods of analysis, mathematical and simulation modeling. Results: Based on two existing mathematical models of inter-car couplings with spring-friction absorbing devices, an improved model of inter-car coupling equipped with spring-friction absorbing devices of the PMK-110 type has been developed. It is shown that this model increases the reliability of calculating the values of the longitudinal forces arising in the absorbing devices of the intercar couplings of the train. Practical significance: The proposed model of inter-car coupling can be used in studies of longitudinal vibrations of a train, since it gives more reliable calculation results for all loading modes.

Purpose: To consider the need for rational choice of the values of automatic control system (ACS) parameters by speed of long freight train locomotive under the condition of ACS management necessary quality provision. Choosing method to solve the task of ACS parametric synthesis and control quality indicators. Finding rational, from view of accepted system of management quality assessment, ACS parameters for trains of various mass and length. Methods: Methods of mathematical and simulation modeling, electric traction theory, automatic control theory, multi-criteria optimization. Results: At parametric synthesis task solution for considered by ACS speed, it’s been indicated that the task’s parameters depend on train length and its mass. Analytical dependences, establishing functional connection between train car mass and ACS parameters by speed, have been found. Practical significance: The obtained dependences can be realized in the form of adapter as a part of automatic control system, allowing to embody operative setting of ACS parameters in dependence of train car average mass.