Using the same experimentl method reported in the previous thesis, a series of factor tests were carried out.
The soil stress and the resistance force were analyzed.
The main results are the following:
(1) Elastic blade and spring-supported blade showed greater horizontal resistance than the rigid blade. This is caused by the greater compressive tendency of soil just in front of the blade.
(2) Decrease of blade length causes slight increase of horizontal resistance, which comes from the increase of cutting resistance and too much decrease of shearing action.
(3) Increase in width of the unit blade (totally, the same width) requires a little greater resistance.
(4) Because of the clogging of the furrow slice between the unit blades and increase of compression of the furrow slice, decrease in depth of unit blades causes much increase in resistance.
(5) As for the shape of the cutting edge, shorter edge line (especially the vertical part) causes smaller resistance.
(6) Smaller γ angle causes increase in resistance, which comes from greater cutting and frictional resistance.

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Lateral motion and yawing of plow is discussed from the viewpoint of stability problem. Plow is not always stable in the motion of horizontal plane because of its resistance increments for furrow-width variation and attack angle variation. So some compensating devices are needed for stable plowing.
When the motion of a plow is discussed, relatve motion of the tractor must be taken into consideration as the mass of tractor is not so large comparing with that of plow. In this treatment, resistance of plow is linearized around the steady operating point, and the motions of the plow and the tractor are governed by the differential equation of 8th order.
Numerical examples are given in Bode plot representation. For an example of Massey Ferguson FE-35, corner frequency lies between 0.1 and 1 cycle per second.
Stability compensation by three points link hitch and gage wheels will be discussed in the succeding paper.

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Rolling motion of a plow, tractor and also of a hitched plow is discussed here for plowing stability and tractive performance. Gravity center of a plow must be located so that the restoring moment against the rolling motion is expected. Conventional hitch-point analysis should be reconsidered taking account of the rolling moment. When three points link hitching is employed, rolling stability of a hitched plow is maintained largely by rolling resistance of the tractor.
Characteristic frequency of the hitched plow for an example of Massey Ferguson EF-35 system is about 5 and 12c/s and the frequency responce is rapidly decayed over that frequency. This is desirable for pulsive disturbances encountered in the cource of plowing.
Numerical calculus of the rolling motion, which is governed by the differential equatuion of 4th-order, is made using electronic analog and digital computers and gives fair agreement with experimental results.

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(1) The declination of lubrication oil depends on revoluting time and load.
(2) Perfect drain and engine flashing usually make a lubricating condition good.
(3) When the multigrade oil is used, good result will be expected.

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This paper contains the results that were obtained from some experiments, their considerations about the characteristics of the reaction forces acting on the lugs and the rolling resistance of a driving wheel with lugs on sand of sand hill.
(1) The process curves of the reaction force acting on the lugs vary according to the height and the fitting angle of lugs.
(2) According to the increase of the pull load, the slip of the driving wheel increases gradually and the negative part of the process curve of reaction force decreases simultaneously.
Therefore, the relative increase of the reaction force corresponds to the increase of tractive force.
(3) The rolling resistance of the driving wheel with lugs varies according to the number of lugs, and there is a certain number of lugs in which the rolling resistance takes the minimum value.

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The deflections of the tractor tire, the diameter and width increases, under the various loads and inflation pressures were tested. And the energy when the tire was deflected on the smooth surface was measured by the traction method on the concrete floor in the laboratory
The heights of rubber part of the tire y had the relations with the inflation pressure x as y=Ax^B. The heights were rapidly increased with the inflation pressures when the tire had the pressures below 0.5kg/cm² as shown in fig. 2. Width was decreased with the inflation pressures under the small loads, while it was increased under the large loads. Below 0.5kg/cm² of the inflation pressure the width was increased rapidly.
Energy for the deflection of the tire, in other words the rolling resistances caused by the tire deflection on the smooth surface y, had the relation with the inflation pressure x as y=a/x^b as shown in fig. 10

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Pressure distribution pattern under the tractor tires is the definite tactor for the wheel sinkage and the most important elements for the traction caused by the friction between tires and soil and they were reported by many researchers.
In these reports, they only mentioned as the tire had no lugs and even if they had many lugs, the effects of them were all neglected.
In this test, the effects of lug to the pressure distribution pattern were measured and it was clarified that the lug had the large effects for the distributions as in figures in this paper.
It was described in many reports that the traction was the results of the shearing resistances of the soil between the lugs. But the pressure of the soil which may be sheared were very smaller compared with the pressure of the soil under the lugs. Accordingly, it may be seemed that the traction were almost indebted by the friction between the soil and the tire surfaces.
In this test, the pressure pattern were measured by the small cone penetrometer like the pencil and the loads on the tire were checked by the total of the ground contact pressures as in the table.

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This paper reports the conclusion of studies on the available uses of pan-breaker. The studies were conducted to find out the lasting effect of pan-breaking for 3 to 4 years at the three regions (East Hokkaido, Middle Hokkaido, and North Kyu-shu). Kind of soils are volcanic ash soil, clay loam soil and hard clay soil respectively.
The items of experiment are operating test, resistance of soil penetration, soil physical properties, and crop growth and yields. The troubles at each regions are reducing of crop yields by the soil freezing, the drainage, and soil compaction etc.
(1) The rate of operating. Two implements are trail behind 3 chisels (beet wings attatched) and rear mounted 1 chisel (no wings). The drawbar horse power of tractor are 80hp (crawler type) and 50hp (wheel type) respectively. The draft is 3.8 ton at the depth of 50cm, and operated area per hour is 35 to 45 ares at the speed of 0.7-0.8m/s.
(2) Soil penetration. The cone type penetrometer is a useful tool to sound the hardness of soil profile in field investigations. Equi-penetration curve is always used to find out the lasting effect. By the use of one square inch cone, the limited resistance is 40kg for crop root growth. The lasting effect of operating is three or more years at least. However, it is important things that the lasting effect will be reduced by the traffic of heavy duty implements.
(3) Soil physical properties. The looseness of soil can be compared by the apparent density and porosity. The apparent density at treated plot is 0.1-0.2 less than untreated plot. Porosity increases 5 to 10 per cent at the treated plot.
(4) Soil freezing. It has been resulted into the formation of plane structure, the soil errosion, and the reducing of fertility of soil. The profile of frozen soil is shown in Fig. 2 a, b. At the pasture land, ice pillars have been formed at the depth of 5 to 15cm below the soil surface. The hard pan at the crop field, ice crystals are found mainly at the lower layer in the frozen soil, and the amount of ice crystals are little by the double treatment (60cm and 30cm). At the pasture land, they are distributed to the over-all layers of the frozen soil and concentration of ice are little.
(5) Crop growth and yields. Any crops at the low swampy land did not grow before treatment, but considerable amount of sugar beets was yielded after the treatment. This is due to drainage effect. The height of dent corn is higher than untreated plots. The yields of potato and sugar beets at the deep treated plot are increased. At the hard clay soil, the yields of wheat is about two times of the rate at the untreated plot. Especially, the wheat above the subsoiling shows better cropping than the others.

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The continuous plowing method has a good result on the plowing capacity but it has following faults.
The unplowed land appears on the four corners of the field, and moreover, they occupy fairly large area. The unplowed lands by throw-out plowing are smaller than those of throw-in, but the crescent-shaped unplowed lands that appear in every turning are irregular in shape, and is difficult to plow. Therefore, it requires a lot of time and hard labour to treat them. The decrease of the plowing widh, the cause of occuring of those un-plowed land, is in inverse proportion to the radius of turning. Their relations are as follows:
r≤5.5m b′=w
15m≥r≥5.5m b′i=k-90/r
r≥15m b′=b
Moreover, when we plow during turning, the inversion of furrow is bad, and particularly, the plowing depth becomes shallow because of side-pressure.
There are following ways to prevent the decrease of plowing width in turning. First, it is better to make the wheel-base short. Second, the width of the rear tyre should be the same of the bottom plow, so that the rear tyre may not move to the center part. Third, we improve the construction of the tractor body and we shall be able to get the turn-table type that has the hinge on the center frame of the tractor body, so that the locus of the rear wheel will coincide with that of the front wheel and the decrease of plowing width will be less.

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