Technology of Creation of Three-Dimensional Model of Tractor Transmission in Program Package “Universal Mechanism”

This paper describes the technology of creating the model of drivetrain of the tracked agricultural tractor Chetra 6C-315. Two-dimensional dynamic models do not provide an accurate representation of the whole complex of active and reactive forces acting on moving masses. Three-dimensional models provide much more opportunities for describing loading processes. The model was created in the program package “Universal mechanism” on the base of the kinematic scheme of transmission of tractor CHETRA 6C-315. The model consists of three main types of elements: “rotational joint”, “gearing”, and “planetary gear”. A program package includes a mathematical description of each element and the user has to specify only elements properties. In a planetary gear model for defining sun gear, crown gear, and carrier, joint with six degrees of freedom was used, and the connection between satellite and carrier is described with the rotational joint. As the result of full description describing of all elements of the tractor transmission, its three-dimensional model was obtained. The model takes into account reactive forces and moments from the casing and frame elements, and also from the engine. The model allows specifying a character of engine torque changing during the research. The characteristic of the engine torque is obtained from an indicator diagram beforehand. The analysis of results allows to find transmission areas with the highest dynamic load and to propose design ways for decreasing this load.