The measurements of sinkage of the various running elements of the several farm tractors, such as wheel type, half track type, strake wheel type, girdles and dual tires, having the various drawbar pull loads were tested on the wet paddy fields. Summarized results of this test are as follows.
1. Sinkage of the running elements of the tractor increased with increase of the drawbar pull and the relation curves between both factors were quite similar with the curves of the drawbar pull vs. slippage reported previously in Part IV of this series. On the fields having the dropping phenomenons of the curves of the drawbar pull vs. slippage, the quite similar relations of the drawbar pull vs. sinkage were shown as the broken lines in the figures in this report.
2. Then, we can get the linear relationships between the sinkage and the slippage of the running elements of the tractors with the increase of the drawbar pull, except the sinkage at 100 percent slippage, which was excavated by the treads of wheelsor tracks.
3. Half tracks used as semi-crawler type tractor had better floatations and less sinkage than tires. Sinkage of the strake type wheel were larger than that of tires or half tracks by the depth of projecting parts.
4. Comparatively hard field in the wet paddy fields, the surface crossing type such as half tracks had less sinkage and larger drawbar pull than subsurface crossing type as strake type wheel. On the other hand, on the fields havinig the soft layer on the top of them, as puddling field, the surface crossing type as strake type wheel had the priority than half tracks and less sinkage and larger drawbar pull.
5. Sinkage patterns of the half tracks were arc type ditches having the two peaks, one of them was found at the bottom of the rear wheel axle and the other was at the axle of the supporting wheel. Sinkage or drawbar pull of the half tracks would be more improved if these arc type patterns are more flat.