This article highlights the solution to the problem of building a dynamic mathematical model and its research. The analysis of the processes taking place in the hydraulic drive of the transfer of the wide-grip agricultural unit from the transport position to the working position was performed. Search and analysis of already existing hydraulic systems, principles of building mathematical models and methods of their solution were carried out. It is shown that one of the directions of development of the market of modern agricultural aggregates is an increase in the number of structures with an increased width of grip. It should be noted that this design feature has several advantages from the point of view of fuel economy, reduction of the number of passes of the unit and, as a result, reduction of the amount of compacted soil. Which, in turn, contributes to the preservation of its condition and increases the efficiency of its use. The disadvantage of wide-grip units is the difficulty of maneuvering when turning. Therefore, to ensure quick maneuvering, units of this type must be equipped with an effective system for transferring the machine from the transport position to the working position. A hydraulic drive is used to meet this requirement. This type of drive has a number of advantages - compactness, power, the ability to work at high speeds and the ability to dampen vibrations. The scheme of the hydraulic drive for transferring the wide-grip unit from the transport position to the working position with gradual switching on of the hydraulic motors is proposed. A mathematical model of the hydraulic drive has been developed. The composition of the proposed mathematical model includes the balance equations of the amount of liquid, the equations of forces and moments acting on the working bodies of hydraulic motors. The obtained solutions of this system make it possible to conduct a thorough analysis of the processes taking place in the hydraulic drive, and to identify such ratios of hydraulic drive parameters that ensure high-quality operation of the system.

As you know, one of the areas of development of modern agricultural machinery is to expand their functionality, increase capacity and productivity. The solution to this problem is possible through the use of powerful small-sized drives - namely hydraulic drives. These properties of the drive of this type have become crucial for its widespread use in agricultural machinery. Today, the hydraulic drive is used to drive the working bodies of machines, and as the drive of the main movement of self-propelled agricultural machines. The main hydraulic unit that drives a self-propelled agricultural machine is a hydrostatic transmission. Significant competition in the market of self-propelled agricultural machinery has led to an increase in the level of technical requirements for both agricultural machinery in general and hydrostatic transmissions operating in their composition. At the same time, further increase of energy saving and economic efficiency becomes especially important. The solution of the set tasks is greatly facilitated by further hydrofication of the drives and working bodies of agricultural machines. The most successful solution to this problem is the use of a hydrostatic drive, a typical representative of which are hydrostatic transmissions such as GST-90. The analysis of theoretical researches is carried out, the design of the stand for carrying out experimental researches for the purpose of confirmation of results of mathematical modeling is offered. Measuring and recording equipment for conducting a physical experiment is described. The coincidence of the results of experimental studies of hydrostatic transmissions with the results of computer simulation based on the developed mathematical model confirms its adequacy and correctness of the assumptions. Due to this, it is possible to recommend using the results of mathematical modeling in the design of new designs of hydrostatic transmissions.

One of the factors ensuring the stable development of agriculture is high-quality and reliable equipment. Today, the development of hydraulic drives has largely led to its widespread use in agricultural machinery and tractors. One of the systems fully hydrogenated in heavy agricultural machinery is the steering system. Hydrovolume steering system has the following advantages - compactness, freedom in the layout of the machine, high efficiency, accuracy, the ability to transfer significant effort to the steered wheels with minimal effort of the operator. Disadvantages include certain restrictions when the associated load on the steered wheels when turning. This parameter is one of the indicators of the quality of hydrovolume steering systems and the minimum effort at which the process of assembling the wheels begins, is regulated by international standards. The article performs mathematical modeling of the hydrovolume steering system. The mathematical model consists of the equations of continuity of flows of the working fluid, the equations of moments and the Lagrange equation of the 2nd kind, which describes the operation of the planetary gearbox. The search for solutions of this model was carried out using the original software, built on the basis of the Runge-Kutta-Feldberg method with an automatic integration step. As a result of the analysis of the received transient processes areas of steady work were constructed that allowed to receive a ratio of parameters of system at which its steady work is provided. The proposed design solution allowed to increase the limit value of the associated load in excess of which there is a spontaneous movement of the steered wheels. The analysis of the workload at the associated load had a significant impact on the values of the overlap of the working edges on any work of the system under the action of the associated load, and the correct selection of these floors can achieve significant quality improvement.