Author has tried to find out new method to investigate tillage machinery with minimum resistance force, and took consideration on soil stress distribution in tillage and on the type of soil failure, on the ground that soil stress directly determines soil resistance. In consideration of normal stress and shearing stress in plane of failure, there must be five types of soil failure, namely, compressive shear, simple shear, ten sile shear, rupture, breakage with cutting edge. Based upon Coulomb's equation and interlocking of soil particles, the resistance force in every type of failure was considered and came to the following conclusion; the smaller the normal stress in plane of failure, the less the resistance is. In soil cutting action, breaking resistance and frictional force are two main components of resistance force, therefore in order to reduce them, we must seek for tillage method in which the value of normal stress in plane of failure and on the plane of cutting blade is minimum. Then, author tried to disclose the factors which greatly effect upon soil stress distribution in tillage, and classified various kinds of tillage implements on the base of these factors, finding that in spite of many various tillage machinery which have hitherto appeared, there can be other kinds of new tillage machinery.
The field study of subsoil pan-breaking at the experimented field in Hokkaido University has been carried out since 1958. The primary objective was to improve the aeration and the internal drainage of the subsoil. The results for the first period of the study were reported in Journal of the Society of Agricultural Machinery, Japan, Vol. 21, No. 2, 1959. The previous paper (Report III) on the investigation conducted in 1959 at the same district was reported in this Journal Vol. 24, No. 2, 1962. This article is a progress report summarized the investigation in 1960. Results were as follows; (1) After melting of snow in early April, the soil resistance of penetration was lowest at the depth of 30 to 32cm below the surface. In May and October, the resistance increased at the depth of 30 to 45cm below the surface. However, the subsoil pan-breaking was not effective at the plot where is rolled surface well. (2) Soil porosity at the untreated plot was 53 to 63 percent. On the treated plot, poroscity is about 60 percent or more at the depth of 45 to 50cm below the surface. (3) Coefficient of soil permeability in October was larger at the depth of 45 to 60cm. (4) Growth and yields of sugar beet on the treated plot were moderately high.
We studied the characteristics of the soil displacement for the rotary, crank and screw type tillage machines at the upland field of Utsunomiya University. In this experiment, we put small pieces of chalk on and into the soil, and tilled, then by measuring the displacement of them we investigated the soil displacement. (1) The values of the mixing ratio and the scattering ratio in middle stratum of soil are higher than the upper and lower one, and the values of them are shown in Table 3 (the scattering ratio) and Table 4 (the mixing ratio). (2) The values of the inverting ratio and the burying ratio are lower than the mixing ratio and the scattering ratio in all cases. (3) There are some correlations among the values of the mixing ratio, scattering ratio, inverting ratio and burying ratio that were calculated by the equations in preceding paper.
The writer investigated the influence of the lug angles and the weight per unit length of the rotor, upon the load characteristics of puddling rotors. The results can be summarized as follows: (1) To diminish the load of the puddling rotor, the cutting angles of the lug should be decreased, the rotations lowered, and the machine weight per unit working length lighter. From the writer's experiment, it can reasonably be said that the lug angles range from 45° to 60°, the weight from 0.7kg to 1.0kg per centimeter, and the rotations of the rotor from 46 to 72per minute. (2) Greater weight per unit working length and smaller angles of the lug made rotors sink deeper, which in turn increased the working area in cross section. As the result, the puddling resistance increased. In determining appropriate angles of the lug, it should be noted that smaller puddling resistannce and higher breaking and-stirring effect be taken into consideration, as well as the load characteristics.
The purpose of this experiment is to testify the theorems which were previously mentioned in the statical analysis. In this experiment the traction efficiency μ was measured and the effects of the wheel weights were analysed both theoretically and experimentally. The new ideas of the critical hitch height and pull angles were proved in this experiment.
The influence of soil condition, working condition and the shape elements of rotary hoe blade with respect to the load characteristics of the up-cut method of the rotary cultivation was studied. The results were as follows: The direction of vertical and horizontal cutting force in the up-cut method were reverse of the down-cut method, namely vertical downward force and backward tractive force arised on the blade. The vertical force of up-cut method was a little larger than the down-cut method, and the peak of vertical force came out behind that of horizontal force. The power requirements were a little smaller than the down-cut, if the vertical cutting area of up-cut method was the same as down cut, and they decreased more when the resistance became smaller. As the reason of these phenomena, the author considered that the soil breaking was caused mainly by tension. With respect to the both cutting methods, the change of cutting angle by the change of rotating angle, lead or pitch of blade were investigated at the stationary status and the moving status. Consequently, the values of shape elements of blade should be selected to the characteristics of soil scattering, soil turning and soi-breaking were not injured at the long lead in the multil blade Howard's type.
In this report, the static stress distributions and their values in chassis and body of one-body type small tractor were studied. First, the stresscoat was used to determine the stress distribution, but was found that this is not a suitable method. Next, the strain gauges were used to measure the stresses and the following results were obtained. (1) Bending and normal stresses were very small. (2) The stresses in the hitch and the gear box about the axle were maximum. (3) The stresses were maximum when the tilling depth was 6cm.
Since 1947 we have accumulated efforts to realize small side-delivery windrowers (Journal of the Society of Agricultural Machinary, Japan, Vol. 10-Vol. 23), one of which, HR602, gave satisfactory results and is being introduced into Japanese farming from the view point of labour saving. The windrower is simple in mechanisms and can be attached to the uni-axle tractor. The adaptability of the machine for lodged crops, however, is rather poor. This urged us to construct experimental combines though we have not got at a clear notion that how the feature of the Japanese agriculture in the future should be and that what the acreage of a single paddy field and the size of combine in the future will be. The principal objects of the construction were to make the losses of the grains as little as possible at the harvest of lodged rice and to make the machines as small as possible. We constructed three combines in 1961, the technical specifications of which are given in Table 1, and carried out some field tests. Though the above cited objects could not be realized for the shortage of time shared for designing and the shortcomings in mechanisms caused by the lack of fundamental data. From the experiments, however, we found out many problems which will help us in the following designing of combines. Given below are short explanations of the machines and the results of the experiments. 1) HT612 has a side delivering (L-shaped) header with a cutter bar length of 1.1m. The undershot type elevator with slatted chains was adopted, the lower shaft of which was designed to be common to that of the auger. Cleaning sieves were avoided, for the recleaning after artificial drying is an indispensable operation under Japanese climatic conditions in any case. Thus we aimed to make the machanisms as simple as possible, but the results of field tests were unsatisfactory. A fatal defect was seen at the corner of the header auger and the slatted chain elevator. 2) HT613 has two vertical axes with a plate at the both lower ends, on each of which four knife-sections are fixed. Belts and star-wheels were adopted instead of reel. The crop is cut and thrown on the canvas elevator by these rotary cutter head. The width of the elevator' however, was too narrow and the angle of elevation was too steep to allow a smooth flow of crops, which resulted in clogging of crops at the half way of the elevator canvas. The threshing unit of this machine is common to that of HT612. 3) HT614 is of centre-delivering type (T-type) with a cutter bar length of 1.1m. It ran fairly well, but the capacity of threshing parts was observed not to be matched to the other parts. Further improvements of the capacity will be done by the next harvest. Standing on these experiences, we are to design six other models of small combines.
The climatic conditions in Hokkaido is not so suitable for haymaking, so artificial hay drying is one of the effective means to produce a better hay. Especially' if a baler is used, baled hay must be completely dried with haydrier. Though haydrier is not so popular in Hokkaido, forced-air mow haydrier with slatted floor system was designed and constructed inthe farm of Hokkaido University, standing on above mentioned reason. The performance tests of the haydrier were carried out in Autum, 1961. The results can be broken down as follows: 1) The static pressure on the bottom of the piled bales was about 12-14mm at the middle part of the floor, when the bales were piled as high as 2m. However the pressure at the oppositeside of the main duct was about 7-10mm. The air losses could be found at the portion of 1 meter from outside of the piled bales. It is one of the most important problems to get maximum efficiency that the bales of the outside must be piled as compact as possible to keep from air losses from around the piles. 2) The drier was driven from Nov. 1st. to Dec. 1st. The mean temperature and humidity of outdoor were 4.5°C and 71-72%, respectively. The fan was driven in the daylight, except when the humidity was higher than 80%. The differences in the temperature and humidity between in the mow and outdoor were 1.8°C and 7.9% while the fan is running, and they were 3.0°C and 4.5% when the fan is stopped. 3) Even though under like this low temperature, the temperature of the bales with more than 25% of water contents raised, when the fan was continuously stopped. The fan should be run, in this case. 4) Since the air flow from the bottom of the pile, the drying speed of the bales on the bottom layer was higher than that on the top layer. Therefore, they can recognize that drying of all bales will be completed when the bales on the 2nd layer from top will be dried. 5) The fan should not be run when humidity is hig her than 80%, except when the temperature of hay raised.