In known scientific and technical literature, insufficient attention is paid to the study of dynamic processes of wheeled vehicles with a steering front axle. The use of front swivel axle on a self-propelled chassis makes it possible to minimize the moment of resistance to turning and reduce the wear of front wheel tires in comparison with rotary guide wheels. This modernization can provide a wider range of attachments for mechanized work equipment. The aim of this work is to increase the stability of the rectilinear steady-state motion of a self-propelled tractor chassis by creating stabilizing moments on the front pivot axle by shifting the axis of rotation of the front axle in the direction of the longitudinal axis of the machine. The stability of the rectilinear steady-state motion of a self-propelled tractor chassis is investigated when creating stabilizing moments on the front steering axle by shifting the vertical axis of rotation of the front axle in the direction of the longitudinal axis of the machine. This scientific article shows that when the steering axle moves, it is possible to reduce the lateral force on the front axle to zero, which makes it possible to reduce the moment of resistance to turning. A straight-line steady-state movement of a tractor is considered, where a violation of the stability of the front steering axle may occur during a short-term impact on an obstacle on the road.  In some cases, the angular acceleration and angular velocity of the bridge in the road plane may be the exciting factor. The loading scheme of a front swing bridge under the action of an exciting angular acceleration is determined.  The calculation of the effect of the exciting factors on the power steering cylinder is presented. The stabilizing moment that occurs when the axis of the vertical shaft of the front steering axle drive is displaced is determined. The differential equation of the front axle's circular motion was analyzed, which revealed its stability under the action of short-term excitatory forces in the rectilinear steady-state motion of the self-propelled chassis. An estimation of the motion of the front steering axle of a self-propelled chassis is presented, with the determined proportionality coefficients and coefficients of the differential equation, which describes the stable motion of the front steering axle in the steady-state rectilinear motion of the machine under the action of short-term disturbing forces. Keywords: self-propelled chassis, front swivel axle, stability, stabilizing moment, steady-state motion

The results of the study of the possibility to improve the process of mechanized hitching of machines and tools into the center zone of self-propelled chassis, using a folding frame and a front balancing swivel axle, are presented. Research and studies that had been carried out earlier in Ukraine and other countries did not allow to solve this problem by the simpler methods. The use of a front swivel axle makes it possible to solve the problem of an automated hitching of implements and tools in the center zone, improve maneuverability and simplify the steering drive of a self-propelled chassis. The scientific novelty of this research is a dynamic model of the vehicle turning in place around one of the rear wheels, when the front axle is turned at an angle close to 90 degrees. The use of a balanced front axle can significantly reduce the moment of resistance to turning. The latter phenomenon has not been studied in the known publications. The aim of the study is to increase the maneuverability of a universal-row-crop tractor self-propelled chassis, including the process of mechanized hitching of implements and tools in the center zone when using a folding technological frame. The use of a swivel front axle allows us to get an ideal turn with any changeable front wheel track that might be changed during the operation of the vehicle. The conditions that make it possible to turn the machine around one of the rear wheels are determined.

В статті досліджуються стабілізуючі моменти на передньому поворотному мосту тракторного самохідного шасі. Метою статті є підвищення керованості і стійкості автомобілів з переднім поворотним мостом за рахунок збільшення стабілізуючих моментів. Представлені результати визначення стабілізуючих моментів, які діють на передній поворотний міст при русі по прямій і на повороті. Запропоновано додатково встановлювати вал приводу повороту переднього моста під кутом до вертикалі в поздовжній площині симетрії самохідного шасі. Визначені аналітичні залежності стабілізуючих моментів від лінійної швидкості самохідного шасі, кута та кутової швидкості повороту моста, а також від геометричних та вагових параметрів машини.

В статті досліджується найбільш напружений режим навантаження рульового керування тракторного самохідного шасі при максимальній частоті впливів водія на руль. Метою статті є оцінка граничного навантажувального режиму рульового керування тракторного самохідного шасі з переднім поворотним мостом. Представлені результати визначення параметрів граничного (найбільш напруженого) режиму навантаження рульового керування перспективного тракторного самохідного шасі з переднім поворотним мостом. Отримана математична модель дозволяє оцінити динаміку зміни тиску рідини в силовому циліндрі при граничному режимі навантаження рульового керування.

One of the common causes of road traffic accidents is the skidding of the car during braking with the rear wheels locking in advance. It was determined that the cause of the car skidding is the anticipatory blocking of the rear wheels of the car. However when building dynamic and mathematical models the degree of excessive braking of the rear wheels wasn't taken into account. The conducted research made it possible to obtain analytical expressions for estimating the steady speed of the car when braking with locked rear and unlocked front wheels at different degrees of underutilization of the coupling weight on the front axle. A new indicator has been introduced – the degree of underutilization of the car's hitch weight when the rear axle skids. The goal of the study is to improve the accuracy of the evaluation of the car's indicators when braking with the front non-locked and rear locked wheels by improving the method of determining the total reaction of the road on the rear wheels. To achieve the goal, the task of determining the total reaction of the road on the rear wheels was solved. As a result of the conducted research, analytical expressions were obtained for estimating the steady speed of the car when braking with locked rear and unlocked front wheels at different degrees of underutilization of the coupling weight on the front axle. In the obtained analytical expressions, a new indicator is used – the degree of underutilization of the towing weight of the car