The calculation of stability of tractors in earthworks and in the management and improvement of rangelands and meadows

The calculation of tractors stability is a complicated problem the solution of which requires the full and safe knowledge of all factors affecting it. These factors are the technical components of the tractors such as the horsepower, the weight, the template of support, the velocity of movement, the height of gravity center, the suspension, the shock absorbers, the tires, the size of load of the hauled and carried machinery as well as the length and the height of their coupling. However, these factors which affect definitely the stability are the slope and the category of soil as well as the centrifugal force in turns. During the turns of tractors are developed, as is known, centrifugal tensions that may cause, under specific conditions, instability and side overturning of the tractor. In this paper was determined the moment of stability (WΧg) in the turns, of a classic four-wheel forest tractor. For this purpose was compiled a computer program and was calculated the moment of stability in respect to the distance (Xg) of the machine’s gravity center from the contact point of the wheel-ground (average level of tire), the height (Yg) of gravity center, the velocity of movement (u) and the revolution radius (r). From the results it came out that the stability, during the turns at horizontal ground, is small when the template of support is small, the height of gravity center big, the velocity of movement big and the radius of revolution small.