The 4-wheel tractor is very similar to 3-wheel type car in overturning caused by one hinge point connecting the front axle with the chassis. The critical angle of static ide-overturning of the tractor can be determined by location of center of gravity, tread, wheel base, and height of its hinge point. The stability of the tractor on a side slope is essentially related to the critical angle vesus the angle of inclination.
In this paper, the stability of the tractor is investigated experimentally using the small tractor, such as how the location of the center of gravity is influenced by the position of operator.
The test results are as follows :
(1) The Location of the center of gravity of the tractor is apporoximately equal to the calculated value in the logitudinal and lateral direction but increases in height with the increase of the angle of inclination.
(2) The center of gravity of the tractor increases 19% in height by having an operator riding on it, and then its decrease ratio of the stability is equal to 0.749.
(3) The stability loss increases with more ratio than the value calcullated by the angle of inclination. Therefore, the more effective locating of operator and additional weight should be inverstigated to prevent the overturning of the tractor.