Dynamic Characteristics of Tractors Mounted with Rotary-tillers (III)
Simulation of tractor motion and its application
1979 Volume 41 Issue 2 Pages 207-214
Details
1979 Volume 41 Issue 2 Pages 207-214
The dynamic vehavior of small rear-wheel drive tractors attached with rotary tillers was mainly studied based on the equations developped in the previous report and some fundamental design equations were proposed. The results are obtained as follows:
1. The reduction of the tractor weight of 730kg by 10% caused the increase of the variation of the braking force about by 20% and the weight on the front and rear wheels about by 5%.
2. As long as the imaginary hitch point is located before the center of gravity of tractor, the influence of the differences of the horizontal locations of the point to the dynamic behavior of the tractor was small. The vertical location of the imaginary hitch point gave much influence to the weights on the front and rear wheels. Lower the location, larger the variation of the weights on the front wheels became. However, the maximum weights on the front wheels were almost the same.
3. The reduction of the rotational speed of the rotary axle led to the increase of the variation of the braking force and the weights on the front and rear wheels. This teans that much consideration have to be taken on the rotary blades arrangement when reducing the rotational speed of the rotary axle.
4. The influence of the difference of tractor weight distribution to the front and rear wheels and the tractor mass moment of inertia about a transverse axis through the center of gravity to the dynamic behavior of the rotary-tilling tractor was small.
5. The soil-bin test showed that the coefficient of braking force, which is the ratio of the braking force to the weight on the rear wheels, was about 1.0 as the maximum and decreased to about 0.55 after it reached to the maximum when the tractor walked out, On the other hand, the tractor was stable when the mean value of the coefficient of braking force was less than about 0.43.
6. The critical coefficient of braking force was defined to be the upper limit of the coefficient of braking force in the stable range for a tractor mounted with a rotary tiller and its numerical value was proposed to be about 0.45.
7. The design equation for the optimal weight of tractor mounted with a rotary-tiller was proposed. The variation factor of the coefficient of braking force as well as the critical coefficient of braking force plays the important role in the equation.
