1971 Volume 33 Issue 3 Pages 230-238
The dynamic side-overturning angles of 4 wheel tractors were measured by the method of model test, under the condition that the upper side wheel of tractor travelling toward the contour line got over a mountain shaped obstacle.
The results obtained were as follows:
(1) As regards the dynamic side-overturning of 4 wheel tractor, two methods of model tests were dealt with in this paper: one was the method whick described the dynamic property of rear tire as the restitution coefficient (Method A), the other was the method which described it as the spring constant (Method B). The similitude conditions of both methods are shown as eqs. (3) and (14). Both methods are considered to be useful, and yet Method A shows better accuracy than Method B.
(2) It was revealed that the dynamic side-overturning angle of 4 wheel tractor was expressed as an empirical formula, eq. (24).
Eq. (24) is
αd=[1-q(H0/l)γV/√lg]αs2
where,
αd: the dynamic side-overturning angle of 4 wheel tractor (°)
αs2: the static side-overturning angle of 4 wheel tractor in second step (°)
V: travel speed (m/s)
H0: height of obstacle (m)
l: wheel base (m)
g: gravitational acceleration (m/s2)
γ: constant determined by the elasticity of rear tire (cf. Fig. 10)
q: constant determined by the elasticity of rear tire and tread (cf. Fig. 11)
(3) Eq. (24) indicates that a 4 wheel tractor 1.9 ton weigh overturns sideway on the side slope of above 20°, under the condition: travel speed is, about 2m/s, and the obstacle is about 20cm in blight.
