In order to investigate the dynamic side-overturning of tractors, the authors analyzed the problem mathematically and carried out some experiments with a 4-wheel model tractor whose size was about 1/5 of the ordinary tractor. The main results were as follows: 1) In this paper, the tractor was regarded as a rigid body with a single degree of freedom, and its motion was described by the equation (4). The limits of side-overturning were determined in terms of initial conditions of the equation, namely, φ0 and ω0 or v0. 2) It was supposed that the tractor travelling along a contour line on a slope overturned sideways under the following two states; a). the upper side wheel of the tractor would run up a triangle obstacle. b). the upper side wheel would run against the obstacle and rebound with the restitution coefficient e. Then, the critical running speeds which would cause the tractor to side-overturn in the states were calculated by the equation (8) and (16), respectively. 3) The theoretical equations indicated that the critical angle of side-overturning of tractors decreased with the increase of the height of center of gravity of the tractor, the obstacle size and the running speed. The experimental results agreed more closely with the values calculated by the equation (16) than by (8). 4) As the upper side wheel rises from the ground, the point where the tire of opposite wheel contacts with ground transfers outward and it makes a tractor difficult to sideoverturn. The theoretical values modiffied by such an effect coincided closely with the experimental results. 5) The experimental results showed that the more the center of gravity moved to the front part of the tractor, the more easily the tractor side-overturned. This was due to the fact that the transfer of a contact point of the front wheel was smaller than the rear one, because the tire width of the front wheel was narrower than that of the rear one.
In this paper, the results of penetrating tests of the horizontal cones were reported and discussed to find the way of approaches to the solutions of the prediction methods of the prototype performances from the model tests. 1) The twenty six cones which had various diameters and appex angles were used and the drafts of them were measured under soil conditions of six levels shown in Table 5. 2) Among the diameter of cone d and the draft R, we had obtained the relation R=Adm and the mean value of m was 2.51 on dry sand and 2.18 on saturated mud. 3) The draft of cones was independent from the appex angle except the appex angle of 30 degree. The largest draft was observed in the case of 30 degree for all cones. 4) The variables included in the dimensional analysis of this system were shown in Table 2, and π terms were π1=d/z, π2=α, π3=R/pz2, π4=γz/p. 5) It was difficult to represent the variation of the soil strength in the direction of depth by the cohesion c and the internal friction angle φ on the shearing test, and therefore, they were not taken up in this system. It seemed that the cone penetrating resistance p was the appropriate factor for the design conditions of this system while the cutting resistance of the knife Q was not adequate as one of the soil parameters. 6) Between π3 and π4, a relation π3=A′+m′ π4 was obtained. 7) There was a relation π3=A″π1m″ between π3 and π1 where A″=0.189, m″=2.31 on sand and A″=0.691, m″=2.11 on mud. 8) The relation curves between π1, π3, and π4 or π2, π3 and π4 on the xyz coordinate formed the planes as shown in Figs. 11 and 12. Then, if the design conditions π1, π2 and π4 were satisfied, the values of π3 could be predicted from the model tests. 9) But, there was a problem that the control of the soil strengths was very difficult and the design conditions were not satisfied easily. Then, a ditorted model must be used. 10) When both the model and prototype were tested on the same soil and at the same depth, there was the relation δ2=β2-m″=nm″ between the distortion factor β2 and the the prediction factor δ2, where n was the scale length, m″ the exponent shown in the above. Then, the draft force of profotype R was represented as R=nm″Rm Rm: Draft force on model cones. 11) The compensated model theory was not able to use in this system because the relations of π terms was not in multiplication form.
The author tried to evaluate the stresses in soils (moisture contents=8.3-9.9%) under three rigid wheels by using the finite element method. The results obtained from this study were as follows. (1) The calculated vertical stresses gave good approximation to measured values at the depth 15.7cm under the original surface. (2) Four zones were found in the figure of isobars of shearing stresses in soil under a moving, wheel. (3) Soil particles seemed to move in three zones, that is, foward, backward and lower zone of major principal stresses. The author would like to continue to invsetigate the adapitability of this method to wetter soil conditions.
The purpose of this study is to develop the method for stress analysis of the material as soil, by which we are able to previously calculate the performance for traction or cultivation of field machinery. This paper introduces the static particle model system defined by 5 conditions, which is one of the idealizations of microscopic mechanical structure of the material as soil. The numerical method for stress analysis of this model system is developed. This method is in the category of Finite Element Method, if FEM is interpreted in a broad sense. However, it has the following advantages in comparison to the FEM in a narrow sense. (a) This method is easily applied to the problems including material non-linearity, geometrical noninearity, or plasticity. (b) It is easily applied to the problems generating cracks. (c) It is easily applicable, by easy extension, to the dynamic pobleme including (a) and (b). Alternatively, this method has a weak point that it is difficult to know the correspondence of model system to a real system. This system is nonlinear and non-conservative, therefore we can hardly find the correspondence analytically. We must rely on numerical evidences to find the model to real correspondence. A numerical evidence equivalent to a uniaxial compression test is tried in this paper. The model used has simple and regular arrangement of particles as shown in Fig. 4. Consequently, the following results are obtained in the macroscopic mechanical character of the model system. (1) Several yielding points are found on the curve of axial force vs. axial strain. (2) A hysteresis phenomenon appears on the curve. From these results, it can be estimated that the relationship of axial force vs. axial strain as in Fig. 8. is obtained, if the system contains many enough particles, and the values of Ci are scattered.
A hydraulic driven soil bin test device was designed and constructed. The main characteristics were the followings. 1. Both a driving car for traction and soil preparation and a measurement car were constructed so that the vibration of the former would not be transmitted to the latter. 2. The 30 PS hydraulic driving system covered the speed range of 0.05-3.0m/sec. A high speed range of 3.0-4.2m/sec was covered with the assistance of a pneumatic injector system. 3. A traction-aid device which ncreased the contact pressure of the wheels were attached. 4. The driving car could also be used for instrumentation purposes for large implements and tractors. 5. A fail-safe system was adopted for the electric hydraulic control system. 6. The test-runs under approximate loading conditions showed about the same ultimate speeds as calculated.
This report examines seedbed making performances of various tilling tines (pick tine, knife tine, L-tine) when the tines are used in combination with the shield. 1) Although the tilling power increased when the shield was used, the seedbed making parformances (soil pulverizing, cutting and covering of rice stubble, soil leveling) were improved, and showed an exponential variation with an increase in shield controlling rate CT. 2) Differences in the seedbed making performances among various tilling tines became small when using the shield, and breaking ratio Rf was in a range from 0.75 to 0.79 when the testing condition was restricted to 40%<CT<50%, T0=90mm, and Pi=120mm. 3) Quartile skewness Sq found from a distribution of the pulverized soil diameter became small when the shield was used and difference between various tilling tines also became small when the shieid was used. 4) Weight mean diameter DW2 of tilled clod was expressed in terms of tilling pitch Pi and shield controlling rate CT as DW2=(A0⋅Pin1) CT-n2, mm where A0, n1, and, n2 were constants. 5) Soil leveling was controlled largely by CT, and its relationship with DW2 was also high showing a high significance. 6) The pick tine had a high pulverizing performance and rice stubble disposing performance was also improved by controlling the shield, but entangling of rice stubbles to the tilling rotor and tines became also accelerated at the same time, and pursuance of the normal tilling operation became hard. 7) The L-tine had, in general, a high pulverizing performance, and showed uniform and improved cutting of rice stubbles especially when N8-N28. 8) Performance of the knife tine approached that of the L-tine with N45-N85, but consumed rather high tilling power. 9) Both the rotor and axle torques increased with an increase in the shield controlling rate. However, the axle torque decresed when tines used consumed a large rotor torque. 10) Fluctuation ratio of the rotor torque was smaller than that with out the shield, but the specific torque for tilling became higher and showed a broader torque distribution.
The four kinds of factorial experiments (The Experiment I-IV designed by the split-plot method with fixed and random effect models) were carried out in the fields to obtain the fundamental data which would enable to simplify the design of binding mechanisms of the binder when the physical properties of stalks and sheaves were taken into account. In this paper, the specific value P shown by expression (3) was defined to express the tightness of the bound sheaf. And at the results of measuring values of Experiment I, the weight of sheaf (w), the breadth (d) and length (d′) of binding cross-section of sheaf, the twine length of binding sheaf (L), its tension in d′ direction (T) and those composite variables which concerned with P were analyzed by the use of the variance analysis and the correlation methods. Those results were summarized as follows; 1. The weight of sheaf was affected by the field conditions as well as the other various factors. 2. The natural drying of sheaves was affected by sheaf sizes. And it had direct effects upon the value of T. 3. T decreased rapidly until 60-55% of the water contents of sheaf and at 47-43% of the water contents of sheaf (10 days after), 18-16% of the inicial twine tension were remained. 4. The remaining rate of twine tension (KT) was larger with small sheaf sizes than the big sizes, and affected by physical properties of twine more than the sheaf sizes. 5 If the twine brake was set at constant for the three kinds of tested twine, W and L increased with the sheaf sizes respectively, but the differences among the kinds of twine were not significant. 6. T and the shape of binding cross-section of sheaf were affected by the physical properties of straws and twine. 7. It seemed that the compressibility of straws in a sheaf was influenced by the stress relaxation and elongation of twine and the coefficient of friction and the imaginary contacting area between the twine and stalks. But its effects were very small as the effects of water contents and sizes of sheaf. In the next papers, we shall be analyzed the relationship retween the tightness of bound sheaf and the binding mechanisms of binder by the use of P calculated by the results of Experiment I.
Actual conditions of harvesting and transporting in plastic houses were investigated and following results were obtained. (1) In harvesting of cucumbers, hand-baskets were used in many houses, and simple carts were used in some houses. In harvesting of green peppers, carts are more common than hand-baskets. (2) The harvesting time required was about 120 minutes for a man when the yield of cucumbers was 100kg per 10 a, and was about 250 minutes for a man for green peppers. (3) The time required in harvesting unit weight (1kg) of cucumbers as well as green peppers decreased with yield up to about 100kg per 10 a. and became nearly constant beyond that yield. The time was about one minute for 1kg of cucumbers and about two minutes for 1kg of green peppers. (4) The walking distance at harvesting varied with types of houses, and methods of harvesting and transporting. (5) Though the investigation lacked in fatigue tests of workers, it seemed that the temperature in the house and the solar radiation had marked effects on fatigue of workers.
From surveys of R. M. R. of farm workers using farm machines on paddy fields, the following results were obtained; (1) R. M. R. of using tractors were 1.0-1.8, which were cousidered to have relation with the seating arrangement, controls of tractor, and working speeds. (2) R. M. R. of using power tillers were 2.6-5.2 for tilling, and 1.9-3.8 for puddling. (3) R. M. R. of using rice transplanters (by human power) were 3.4-4.6, of using cultivating implements 5.1-5.2 and of using binders 2.2-2.6. (4) Generally, it was considered that the value of R. M. R. when using farm machinery had to do with working speeds and the condition of field surfaces. (5) R. M. R. of caring the machinery were 2.8-3.1, and of changing wheels or tillage blades were 1.7-1.9.
Three methods of air oven drying;(1) at 105°C for 5 hours with ground grain of about 5 grams, (2) at 135°C for 20 hours with whole grain of about 4 grams and (3) at 100°C for 24 hours with whole grain of about 10 grams, were employed, in order to clear the influence of absolute humidity of room air on grain moisture measurement in the air conditioned room, and the conversion method between the moisture values obtained by two oven methods was studied. The results of moisture content measurement in rough rice were as follows; 1. The differences between the moisture values obtained under atmospheric absolute humidities of 0.002kg/kg and 0.027kg/kg were about 0.9 per cent for 105°C method, about 0.7 per cent for 100°C method and about 0.4 per cent for 135°C method. These differences were almost the same regardless of rough rice moisture contents. Effects of atmospheric absolute humidities on measured moisture contents were larger with lower drying temperatures and shorter drying time. 2. The differences between the moisture values obtained under the same absolute humidity of room air on different days by the same oven method were, however, within 0.1 per cent. Therefore, the umiform results will be expected when room air maintains the same absolute humidity. 3. The authors regarded the moisture values obtained under atmospheric absolute humidity of 0.008kg/kg which was the average yearly absolute humidity in Japan to be the basic moisture content and showed the chart to find out quantitatively the influence of different absolute humidities of room air (see Fig. 3). By the chart like this, it was possible to amend the measured moisture content. 4. With the results mentioned above, the authors propose that the measured moisture contents at a constant atmospheric absolute humidity (0.008kg/kg) may be called the basic moisture contents and those at different atmospheric absolute humidities may be called the apparent moisture contents. 5. Assuming that the weight of the absolutely dry matter of grain is constant in the process of either drying or moistening, the relation between Ma and Mb in per cent of moisture obtained by two oven methods was found by the following equation, (100-Ma)/(100-Mb)=C where C is a constant varying with kinds of materials.
The drying characteristics of a single grain of rough rice was examined for three postures of the grain (shown in Fig. 1) in the air stream which was set at the velocity of 10cm/s. The apparatus used was the same one which was reported in previous papers (References 1 and 3). Results obtained were shown in Figs. 2 through 4. Each drying characteristics of (a), (b) and (c) in Fig. 1 varied with initial moisture contents, the appearance of cracks and individuals. The equilibrium moisture contents of cracked kernels of rough rice were 1 or 2% d. b. lower than those of untracked ones. The effects of the posture were not significant. Therefore the shape of a single grain of rough rice could be assumed as a sphere.
Generaly, pericarps of Kidney Beans are so delicate that it is easy to produce cracks on bean surfaces during through-air-drying. Our recent studies on the crack formations of Kidney Beans during through-air-drying under various conditions may be summarized as follows; 1. The strongest correlation was observed between crackage and drying air temperature, and the correlation became weaker in the order of the absolute humidity of air, the initial moisture content of beans, and the air velocity. (Table 3) 2. Crack formations occurred in the first 60 minutes during drying, and hereafter there was not much change in the crack formation.(Fig. 4, 5, 6) 3. Shrinkage of grain seed showed its maximum value after 30 minutes of drying. (Fig. 7, 8, 10, 11) 4. The crackage occurred parallel to the longest axis of the bean. (Fig. 2)
With the progress of power farming, the number of farmer's blacksmithies has been decreased every year, as their main jobs ars to produce and repair Japanese-hoes. But I believe that their traditional technique is unique and excelent, and worth transmiting. Following is the representative process and technique of producing Japanese-hoes by farmer's blacksmithies in Fukushima prefecture. 1) SS4IP, soft steel is used most often as the base steel of the hoes. Tamahagane (steel made from iron sand), Nabehagane (pan-bottom substitute for steel) and Zenihagane (coin substitute for steel) are used as the substitute for hard steel, and Nabehagane is used most often among them. Nabehagane and Zenihagane, so called by farmer's blacksmithies, are both old cast irons. 2) Pine-charcoal or Chestnut-charcoal are always used in forging, as the temperature of heating rises rapidly with them. Most tools for forging are self-makes by farmer's blacksmithies. 3) Ordinarily, Japanese-hoes are made through five steps, that is, preparing, cutting, forging, quenching, and finishing, and the process consists of eighteen unit operations. The main operations of them are marking-off, chiseling, drowing down, teyori (twisting), tewari (cutting), forge welding, and quenching. The operation of forge welding consists of crushing Zenihagane of Nabehagane into small pieces, placing them on the base steel, and melting them by heating over 1100°C. After then the welded steel is forged ten to twelve times. Quenching is the operation of heating the hoe up to 850°C and putting it into water of 30°C. Forge welding and heat treatment are the most delicate techniques in making hoes.