As a result of theoretical and experimental efforts, innovative scientifically grounded conceptual approach to select hydrostatic and mechanical transmissions (HMT) for wheel tractors designed for agricultural operations has been proposed. The approach is characterized by focusing on kinematic parameters, power parameters, and energy parameters of the transmission while performing technological operation "plowing"; it also takes into consideration braking features of a tractor in the context of various braking types. Application of the approach offers an opportunity to improve technical level of transmissions while updating current wheel tractors and designing new ones; moreover, that will better controllability as well as braking efficiency. The conceptual approach developed on the basis of proposed techniques and applied mathematical models makes possible to determine rational structure and basic design parameters of two-flow HMTs while designing; it also helps formulate recommendations concerning a technique for service braking and emergency braking under specific operational conditions.

This paper considers the braking process of a mine diesel locomotive with hydrostatic mechanical transmission (HSMT) operating according to the "input differential" scheme. Braking process modeling involves four implementation methods. Identification and systematization of basic regularities in the distribution of power flows within a closed transmission contour in the process of braking have been performed with the help of software support developed by means of MatLab/Simulink. The simulation results of braking due to the hydrostatic transmission and the braking system during the movement of a diesel locomotive in the transport and traction ranges are presented in the form of graphical correlations. The process of theoretical studies of the braking process of a diesel locomotive with HSMT operating according to the "input differential" scheme has helped determine that, in terms of deceleration at the expense of a hydrostatic drive (HSD) and braking system while preserving kinematic engine-wheels connection, it is not permitted to implement this method of braking process as it is followed by excess of the allowable value of working pressure differential within HSD up to 2.8 times.

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Basic design parameters, dimension types of hydrostatic transmission and hydraulic efficiencies of transmission in accordance with its kinematics and advertising data for the Fendt 900 Vario tractors are identified. Obtained results are analyzed.