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Abstract

Dynamic properties are characterized by the ability of vehicle to move according to a given law under the action of applied forces. Assessment of vehicle dynamic properties comes down to solving the 2nd (direct) problem of mechanics. In the designing vehicles, on the contrary, according to a given law of vehicle motion, the acting forces are determined, that is solving the 1st (direct) problem of mechanics. The standards for assessing the dynamic properties of vehicles are an expression of the requirements of the company, at this time stage, fixed in the relevant document (standard, technical conditions or regulations). The correct choice of the efficiency standards values, their terms of action helps to increase the competitiveness of vehicle in the world market. In the work of Podrygalo M.A. (assessment of the technical level by indicators of the vehicle dynamic properties) to assess the technical level of cars by indicators of dynamic properties, a new indicator has been introduced – the dynamic index . The analysis showed that, despite the variety of known dynamic properties indicators, there are no criteria in the literature that allow, at the design and testing stages, setting and evaluating the compliance of vehicles with modern requirements for dynamism. The purpose of the study is to increase the accuracy of predicting dynamic property indicators by determining the relationship between power density and vehicle dynamic index. It should be noted that in the work of Podrygalo M.. (assessment of the technical level by indicators of the vehicle dynamic properties) the initial acceleration is determined through the traction force to the driving wheels of vehicle when starting. As we know, it is possible to increase the initial vehicles acceleration when starting by increasing the gear ratio of the transmission in lower gear. This indicator is not related to engine power density. Therefore, in order to predict the increasing of dynamic properties, it is necessary to determine the relationship between power density and vehicle dynamic index Analyzing the dependence of dynamic index shows that it depends on the time of increasing effective engine power from zero to according to the hyperbolic law. Obviously, the value should not exceed unity. Otherwise, drive wheels will drag and the stability of vehicle translational movement will be violated. Thus, the rise time of the effective engine power from zero to its maximum value is a parameter that also determines vehicle dynamic properties. Conclusions – the obtained analytical expressions allow us to predict at the stage of preliminary design indicators of vehicles dynamic properties. Namely: the dependence of the dynamic index on the time of the increase in power to wheels from zero to .