Nowadays, mobile power vehicles (MPV) equipped with ultra-low pressure tires are widely used in agriculture when conducting field work in the early spring. For these power vehicles the funda-mentally new wide-profile tires with low load capacity were developed. Its features are ultra-low intra-tire pressure (10-80 kPa), increased profile width, low ply rating (2-4), high elasticity and soil-covering tread, which in turn provide the necessary traction qualities. Due to the high elasticity of these tires and the relative radial deflection (up to 25 %), the contact area of the tire with the soil increases and the specific pressure decreases. It was determined that due to the cost parameters, a wide range of ultra-low pressure tires, as well as specific features of the tests, they remain insuffi-ciently studied at the moment. In this regard, authors conducted bench tests and determined the basic and traction characteristics of the ultra-low pressure tire with a dimension of 1020×420-18 of Bel-79 model. The equations for the dependence of tire performance on various factors were de-rived. It was found out that when driving on a concrete supporting base, the traction properties of the tire improve with the increase of the internal pressure of the tire and the load on the wheel, but when driving on the field prepared for sowing, the improvement of support-coupling indicators is observed with a decrease of the internal pressure of the tire and the load on a wheel. It was noted that the results of the tests can be used as reliable initial data for the development of mathematical models of the movement of various mobile power vehicles equipped with ultra-low pressure tires.

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The article analyzes elastic elements with a nonlinear characteristic. To improve the smoothness of a truck, a combined elastic element is proposed, including a semi-eleptic spring and an air cylinder, for installation in the rear axle suspension of a car. In order to assess the effect of a combined elastic element with a nonlinear characteristic on the smoothness of the ride, a mathematical model has been developed. The mathematical model allows for a numerical experiment taking into account the nature of the interaction of tires with unevenness of the roadway and the nonlinear characteristics of the combined elastic element.

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On modern cars it is advisable to establish a system of identification, together with a system for tracking biological activity of the driver that enable rapid condition monitoring of the driver. The use of the tacho-graph control, systems of identification and control of driver fatigue allows the possibility of complete and objective tool control of the driver, and the refinement of the work and rest of each crew member as a result it allow improving road safety and security of cargo.