To explain the mechanism of the stickiness of the volcanic light soils, Report (IV), regarding a unit of constitution as the aggregate from the result of my test, made a proporsal to applicate the conception of the critical void ratio of the sand. But it is regretful that my paper had not an experimental endorsement. Having tested with the cylindrical compression apparatus, I got following result: the aggregated volcanic light soils, as well as sands, has the critical void ratio, of which value is about 1.9 when the lateral pressure is 0.3kg/cm2.
In previous paper, I had theoretically introduced the sod plow surface of minimum soil resistance, by assuming the soil had been plasticity and using the calculus of variation. The results of the studies had been as follow; the plow surface had been expressed by the path of furrow slice, and the minimum resistance path had consisted of logarithmic spiral near the share part and of circle near the wing of moldboard. (Fig. 1) In this paper, I studied experimentally these theories, comparing the soil resistance of theoretically introduced surfaces (one being assumed soil shearing strength τe=0.1kg/cm2 and the other τe=0.07kg/cm2) with two ordinary plow surfaces introduced by circular path of furrow slice, one being same boundary condition to the former and the other Stephens type (Tab. 1, Fig. 2, 3), in some soil conditions (Tab. 2). The experimental results with the analysis of variance, showed that differences of the resistances due to plow shapes were significant in plastic soil and deep tillage depth, and the resistance reduction ratios of the theoretical plow to the plow of circular furrow slice path were between 28.4-10.1% and coincided with numerical analysis of theories.
For the purpose of study on the characteristics of the rotary tillage, we constructed a test car running on a soil tank. The test car was driven by I/2_??_ single phase induction motor and the rotary shaft drived by 5_??_ three phases induction motor respectively, the rotary tines are used ordinary tine and flat knife tine (Natazume). The speeds of the car and the rotary shaft are changeable, and the hardness and moisture of soils were maintained as possible as uniformly. The results obtained may be summarized as follows: 1. The driving power of car was very little as compared wth the driving power of tine shaft. 2. When the tine shaft was slow revolution, the driving power per roll (Tan) was the most profitable, and increased hastily when the coefficient of breaking soil is under 200. 3. The tine shaft driving power was influenced by the soil hardness than the type of tines.
On account of the vibration record in the till-ing state of power tiller, we made up the “Vib-ration Testing Table”. The table is fixed rigid and its driving power was absorbed by the fo-llower wheel into the mechanical elements which were unconcerned to the vibration, so that the vibration must have been picked up at the almo-st identical state with the running and tilling condition. The electric measuring apparatus were consisted of (1) pick-up gauge with two plates which the capacitance was variable accor-ding to the vibration, (2) Transducer, (3) Lower frequency amplifier, (4) Constant voltage source, (5) Kathode ray osciliiograph, (6) Continuous re-cording camera. The special feature of this elec-tric apparatus was to record the vibrations sim-ultaneuosly in the different two directions. From those results, the singularities were detected in accordance with the differences of the driving methods.
The properties of corrosion resistance of metallic materials, such as, low carbon steel, three per cent chromium steel, five per cent chromium steel, nickelchromium stainless steel and cast iron to some chemical manures were studied, respectively. As the chemical manures, one per cent and five per cent solution of urea, ammonium sulphate, potassium nitrate, potassium phosphate di-basic, and one per cent and five per cent liquid of calcium perphosphate, and twenty per cent ammonium water were used, respectively.
Defacement of a rubber roll of a rice husker is not uniform with different rotating velocities between the rolls. Therefore, we make it a rule to replace one roll with the other after husking 100-150 bales of rice. So the reporters inquired into the frictional wear of rubber roll. We gained the wear curves of the particular shape to each roll. As the cause of this phenomenon, we discovered that rubber latently has the centrifugal expanding character at high speed revolution. Accordingly the experimental work was done with the deflection sideways and the expansion across the diameter of the rubber rolls. Afterwards our consideration was found out decisively correct. For these experiments we used that precise bench lathe and the automatic adjusting arrangement for clearance of rice husker rolls furnished with the dial gauge and speed regulating mechanism. At the theoretically caluculated analysis of working force of roll surface, we found that the centrifugal expanding force was very little. But defacement of the rolls comes out on account of the indirect condition of expanding deflection with disregard to this force.
The authers investigated on the distribution of threshed materials under the concave-sieve of a threshing machine with self-feeder. The types of distribution of grains are shown at fig. 2, 3 and are determinated by feeding methods and properties of bundles. Main function of threshing is acted in the first 1/3 part of threshing cylinder. Wheats are threshed by higher effect (H) more than rice-plants. Therefore, when we research on the problems of the winnower under concave-sieve, it is necessary to consider on the distribution of threshed materials, as above mentioned.
As it is very important to find the cultivating resistance to improve the efficiency of rotary tillage, the author made the test apparatus for the purpose of measuring the cultivating resistance of a rotary tine (Fig. 1). By this apparatus, the horizontal and vertical components of cultivating resistance of a tine are determined by means of the measurement of displacement of an end of rotary shaft occures by rotary tillage. The soil box is filled with the soil and it is pulled by a motor, a tine cultivats the soil during the soil box is running. Two components of cultivating resistance, revolution of tine, velocity of soil box are recorded by means of the optical method. The sensitivities are about 0.55mm/kg in horizontal and 0.70mm/kg in vertical component. Fig. 4 shows the recording chart of some pointed tine.
1. We study on the effects of particle size, projectional velocity and natural wind velocity for the travelling distance of spray particle. 2. Assuming that a particle in the air receives the air resistance given by stokes'law, moving equations are led, and then the travelling distances are calculated. 3. Flying velocity is more changeable for the smaller partcle sizes, and approach to the definite velocity-terminal velocity in the downward. 4. As to the falling times, the error in calculation with terminal velocity in 1m vertical distance is negregible small ins ize under 40μ in diameter, but in 0.5m distance limited particle size is under 25-30μ. 5. The travelling distances are larger for larger particle sizes and larger initial velocitcys, but on a vertical initial velocity, particles larger than a certain size are drifted on a same place approximately. 6. The smaller particles receive the larger effect by the natural wind velocity, and the effects for larger sizes become fewer. 7. On the test results with solid type nozzles, larger holes in diameter have the larger velocity coefficients and smaller maximum spray particles in diameter.