Soil Reaction to the Lug of Tractor Wheel

Abstract

To consider the relations between the fixed angle of the lug to the tractor steel wheel and drawbar pull or soil reaction, the tests were practised by the device as Fig. 1, and resulted as
(1) Drawbar pull and sinkage of lug into soil, when the soil bin was drafted horizontally, increased with the load on the lug and increasing ratios of them to lug load became large with the angle between the lug and soil surface.
(2) And they were related with sinkage of lug. The resistance of soil became large with the increase of contact area of lug to the soil caused by increases of sinkage.
(3) Specific resistances of the sinking vertical area of lug were independent with the lug angle, and the resistances to the lug at the case when the sinking area was the same were all equal as Fig. 8 (a). But, specific resistances of the vertical area of all lug surface contacted to the soil were varied by the lug angle as Fig. 8 (b). And their curve was quite resembled with the curve of ratio of the sinking lug height to the all lug height in Fig. 9. Then, it was naturally considered that the specific resistances of all lug area were smaller than that of sinking area.
(4) As the lug load which was used to calculated the ground contact pressure were all the same, the pressure of contact shown in rig. 10 shows the area of the horizontal surface of lug consequently. They are rather the problems of compression of the soil, and they must be considered by the soil nature and by help of soil dynamics. From these viewpoint, the tests and considerations are expected to be continued.