On the Side-overturning Angle of the Two Wheel Walking Tractor on Slope Land

Abstract

The angles of static and dynamic side-overturning of two wheel walking tractors were measured to clarify the limit of their utilization on slope land.
The results obtained were as follows;
(1) The authors divided the dynamic angle into two categories, according to the degree of operating muscular strength on handles of tractor:
a) α_dmax, with maximum muscular strength enough to control overturning; b) α_dmin, with loose grip.
(2) The static side-overturning angles α_s in various types of tractors were obtained in the following simple approximate formula: α_s=0.51d where, d is tread of tractor in cm.
It was proved in recent tractors that the angle α_s increased with size of tractor, ranged from 15° to 40°, and does not exceed 40°.
(3) The angle α_dmin was independent of tractor weight, and associated with such factors as travel speed V(m/s), tread d(cm), height of an obstacle H₀(cm) and α_s(°). In case that a contour travelling tractor crosses over a convex obstacle with uphill wheel, the relation mentioned above is expressed in the from:
α_dmin=[1-sin^-1{H₀+γH₀^mVⁿ/d}/α_s]α_s
where, m, n and γ are constants shown in table 4.
(4) The two wheel walking tractors on market have dynamic side-overturning angles of about 15°-20° in case of contour travelling, and are considered to be unsuitable for utilization on steep land because of unstability.