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Under operating conditions, the power plant of a machine-tractor unit experiences changes in a wide range of changes in speed and load conditions. The vibrations arising from this, in addition to discomfort and additional loads on the components and mechanisms of the power plant, also cause excessive fuel consumption and power loss. Reducing the negative impact of vibration on effective performance of a power plant is proposed by creating supports with adjustable characteristics. The stiffness and damping coefficients were selected as the determined parameters. For tractor power plants, taking into account their layouts and design features, a design scheme with two attachment points in front with vertical movement and one hinge point at the rear was selected. As disturbing moments, we consider both the internal imbalance of the power plant itself and the external effects of the variable resistance moment and the shock of the supports themselves. Changes in the stiffness and damping coefficients of the supports used make it possible to reduce the oscillation amplitudes of the power plant under variable operating conditions, which will improve its utilization rates.

Improving the characteristics of the internal combustion engine of an agricultural vehicle is possible by using a hydraulic actuator of the electronically controlled gas distribution valves. The drive ensures the opening of the engine valves by the pistons of the hydraulic cylinders when oil is pumped into them, the valves are closed using valve springs when the oil is drained from the hydraulic cylinders. The advantages of the hydraulic drive are: the ability to turn off the engine cylinders, an increase in the speed of opening and closing the valves of the gas distribution mechanism, no need to adjust the thermal clearances, a constant speed of the valves landing on the saddles. The hydraulic drive is integrated into the engine lubrication system. The working body of the hydraulic drive is engine oil with a pressure of 8 MPa, created by a separate pump. The physical and mathematical model of a hydraulic valve drive in the Simulink environment takes into account hydraulic pressure losses, various inertial effects, elastic-deformation interaction between drive elements, and inductance of solenoid valve coils. The experimental setup includes: a KAMAZ 740 engine, a hydraulic drive for two valves of one cylinder head, measuring equipment. The results of the experiments were recorded using a high-speed movie camera. The determination of the kinematic characteristics of the valves of the gas distribution mechanism was carried out by processing the video frames of the shooting at a known frequency of their fixation. The results of experiments coincide with the results of calculations. The speed of movement of the engine valves, thanks to the use of a hydraulic actuator, is significantly increased compared to the use of a traditional mechanical actuator. The time delay between the supply of an electrical signal to the electromagnetic valves and the response of the hydraulic drive to it is determined. The results obtained make it possible to start creating a serial hydraulic valve drive that improves engine parameters by intensifying and controlling the gas exchange of the engine cylinder with the environment

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