Static characteristics of closed circuit hydrostatic transmission in bench test set-up were scrutinized quantitatively. Unlike fixed-displacement axial-plunger motor, pump used varies continuously its displacement from zero to 30cc/rev. Analyses reveal following findings; 1) Resonant phenomena within fluid lines might appear at 1000rpm in input shaft, and almost identical with output shaft due to inherent periodic variations of flow rate and torque. 2) Maximum overall transmission efficiency can be obtained at allowable maximum line pressure under constant speed ratio. Torque ratio draws nearly linear relationship with speed ratio. 3) P/μn and T/nμD, both are dimensionless terms, show disobedience to wilson's expression. It is of greatly interest to recognize that kinematic viscosity of hydraulic oil plays significant roles for the transmission efficiency. 4) Leakage of pump increases linearly up to 1800rpm in input shaft, after that increases more rapidly. It indicates the failure of application of the theory of laminar flow.
The ultimate objective in designing tractive device for agricultural vehicles is to provide the required tractive efforts with minimum detrimental efforts on soil structure. A step toward determing the method necessary for this design is the measurements of stress distribution in soil under various sizes of tire. In this paper, the change of contact pressure and contact length with the number of passes of model rigid wheel and the influence of rigid wheel sizes on the soil compaction were investigated. The results may be summarized as follows. Nominal contact length decreases and maximum of dynamic contact pressure increases with the number of passes of wheel in drier soil condition. But in wetter condition, the contact length increases due to remoulded soil with number of passes of wheel. The ratio (Pdy/Pave) increases in wetter soil condition. The results that deeper sinkage, greater contact pressure and higher dry density would be gained in smaller wheel as the result of travelling test using three wheels were illustrated.
In order to find out whether lower pressure tires would be able to be utilized on a sand dune field, the authors tried to investigate the different effects on the performances between a conventional tire and lower pressure tires if the weight on the wheels and the inflation pressure were changed. Tractor used in this experiment was a walking tractor, which was powered by 4.5ps/1500rpm engine. The following results were obtained. 1) By changing inflation pressure under the condition of the same weight on the driving wheels, the driving force and the drawbar pull become larger with the decrease of inflation pressures. 2) By changing the weight on the driving wheels under the same inflation pressure, the driving force and the drawbar pull increase with the additional weights on the driving wheels, but increasing of the driving force is larger than that of drawbar pull. 3) Comparing the driving characteristics of different tires with the same slipping ratio, rolling resistance decreases while the drawbar pull increases, when the width of the tires of the same diameters increase. Increasing both the diameter and the width of the tires, driving forces increase. However, rolling resistance is not always decreased. 4) Rolling resistance has a tendency to increase depending on the decrease of inflation pressure under the condition of the same weight on the driving wheels. At lower inflation pressure such as 0.4 or 0.6kg/cm2, the coefficient of rolling resitance is observed to have a decreasing tendency depending on the increasing weight on the driving wheels, while in the higher inflation pressure i. e. 0.8, 1.0 or 1.2kg/cm2, this remains nearly constant. 5) Driving forces at 100% slippage increase proportionate to the additional weights on the driving wheels but these are different between tires or inflation pressures. 6) Lower pressure tires show better tractive performance than a conventional tire on a sand dune field, and would be able to operate to some extents.
Greater stress should be placed on the dynamic analysis of tractors during rotary tillage. To clarify these pending problems substantially three kinds of analysis were conducted under tropical conditions: 1) Power distribution during tractor rotary tiller operation. 2) PTO torque distribution by means of extreme value method. 3) Power spectral density (PSD) analysis of PTO torque fluctuations. To record the rear wheel shaft torque, a strain gege type transducer was fabricated at the International Rice Research Institute, the Philippines. The following conclusions can be drawn: 1) In upland, major tractor power consumption was directed to required PTO hp showing in contrast the slight variation of required rear axle hp lay thrust action (Tab. 3). It can be noted that the required rear axle hp might not exceed 5.0% of the corresponding required PTO hp. In lowland difference of these two values on required hp became smaller gradually if not rapidly with the increase of travel speed (Tab. 4). It might be of interest to note that under heavy wetland conditions like treatment g in Tab. 4, the rear axle torque showed more than three times than that required in upland conditions. 2) Every curve shown in Fig. 10 can be considered as nearly normal distributions. Values as the foot of the extreme sides in reference to mode range±1.7 times in the 1st and in the 2nd gears while±1.4 times in the 3rd and in the 4th gears. Absolute values of mode in lowland go so much down as compared with upland. Comparing results with upland in the 1st gear, it shifts down to half for crest and trough and in the 2nd gear almost identical to crest of upland but half to trough, and then decrese from 1/9 to 1/11 in the 3rd and in the 4th gear (Fig. 11). It is a salient feature to observe the action of negative torque due to big inertia force of the rotary tiller itself and small loads under this field condition. 3) It is clearly evident in Fig. 12 (a) that dominant frequency, that is 109. 1cps, seems to be inherent one composed of intricate accumulative noise for which specification, arrangement and natural frequency of rotary tines might have major effects. What is more, a couple of distinguishable frequencies can be seen in Fig. 12 (b), in which slack and frequent periodicity can be recognized. The former shows 12.0cps which approximates speed of rotary tine shaft, thus another periodicity shows same frequency as Fig. 12 (a). In Fig. 12 (c), earlier periodic wave collapses into less amplitude gradually with lapse of time tending to show a certain frequency, 119.1cps. Although the wave form in Fig. 12 (d) looks random, it can be recognized that sinusoidal phenomena might be exposed on the outside clearly indicating 61.7cps. Pronounced values in the PSD correspond completely with the frequencies which were evaluated in the correlogram at time domain and hence it is easy to observe the extent of intensity of each frequency quantitatively. Travel speed seems to affect the transfer of frequency. But these values coincide approximately with the caluculated value in terms of line spectrum (Fig. 9) and so validity of the theory of rotary tine arrangement is partly verified.
Plastic coated moldboard plows were developed in order to prevent soil sticking when plowing the volcanic light soils, and the problem of wear of plastic sheet was occured. The writers carried out the study on the effect of the qualities of the particles in volcanic ashes on the plastic coated moldboard plows, and the following results were obtained. It was found out that the wears of plastic sheet were very different in districts, that is, the amount of wear was 6.7%/10ha in Yuni town, but was only 1.1%/10ha, in Memuro town and it seemed that this difference was dued to the qualities of volcanic soils. To pursue the cause, the qualities of typical volcanic soils in Hokkaido (i. e. soil texture, compressive breaking solidity of soil particle, and shape of particle) were studied. 1) The content of coarse sand (0.2-2.0mm) of Yuni town volcanic soils was 61.4% and that of Memuro was 21.1%. Therefore, it was concluded that the more content of coarse sand the more the wear of plastic sheet. 2) Both the compressive breaking solidity and the content of such particles effect the wear of the plastic remarkably. The breaking solidity of Yuni town soil was about 791gr and that of Memuro was 221gr, i. e. the former was 3 times as strong as the latter. 3) When the shape of the particles is more angular, the scraping or scratching effect on the surface of plastics becomes stronger, and the life of plastics is shortened. The shape of particles of Yuni was angular, but that of Meruro was roundish. 4) The factors 1)-3) may act on the wear of plastics individually, but generally they interact to increase the wear of plastics.
(1) An automatic feed-rate control designed for the hydrostatic-driven combine of head feeding type was tested. This automatic control system consisted of a two inputs system for feed rate sensing with a straw layer detector and a threshing torque sensor coupled with spring-mounted idlers, electric AND and OR switching circuits system with micro-switches and the feedback control system to the travelling speed (Fig, 1). (2) The electric switching circuit for speed increase was connected in series and that of speed decrease in parallel. The feed rate of combine was controlled to increase the speed, when both the straw layer and the threshing torque were under the lower limits; and to decrease the speed, when either of them was over the upper limits. The manual control of speed was done with the main switch. (3) In tests using only the straw layer sensing, control was good enough to keep the feed rate and the loads of combine elements constant, but was not so effective to prevent overloading of the threshing elements. (4) In tests using only the threshing torque sensing, control was not good due to the dead time in the conveyer which feeds the material to the threshing elements and the Coulomb friction of the sensing device. (5) When two inputs were used many tests were not successful due to the difficulty to get correct setting of the micro-switches.
As it was undesirable to use the gasoline engine for the cart in a vinyl house, we produced by way of trial two electric carts that used battery as electric source. The results of the performance test are summarized as follows. 1) The outline of the battery carts; the cart No. 1 was equipped with 12 voltage motor and the cart No. 2 (improved cart) was equipped with 24 voltage motor. It could be loaded with 50kg for the standard and had travel speeds of low speed (about 30cm/s), middle speed (about 45cm/s) and high speed (about 60cm/s). Further, it could go back with the same rate for each speed. 2) It seemed to be sufficient that the maximum motor output of the battery cart was 130W, For example, in the case of the cart No. 2, when it loaded 50kg and travel speed was low, middle and high, input were respectively 80W, 85W and 100W. 3) The overall efficiency on input basis was 30% at maximum. 4) Continuous operation hours were 3 hours for the cart No. 1 and 4 hours for the cart No. 2 when they were loaded 20kg and travel speed were high. 5) There was no significant difference in operation efficiency between the harvesting operation that used hand-basket and the cart. But the travel distance of the operator was shorter for the cart than for the hand-basket, and it was recognized that the cart had effect on labour reduction. However, in the case of cucumber of a little yield, there was not so much difference between both travel distances, and the favourablity of the cart was vanished
The author has classified those factors which some influences on the field work efficiency η of rotary tillage by tractors into 5 groups (shown in Tab. 1), and then investigated the degree of their influence by analysing the date obtained from 65 cases, the author had measured himself. 1. As for square fields the author studied the relation between the theoretical field efficiency ηth and the area of the field A and its length-ratio F. The author calculated the value of mechanical Characteristies of the tractor a and a/l, from 65 cases above mentioned. During standard work, F showed less influence than a and a/l did. Though A being expanded into more than 30 ares, η showed little improvement. 2. As for irregular shaped fields, the author thought out their equivalents in square-shaped field and calculated its length-ratio F, which the author called coefficient of shape of field and by which the irregular shaped field could be compared with other field with ease. Then the author applied this method to the 65 cases and got the value of F for each respectively. The value of F in irregular shaped field was very small in general, sometimes much smaller then 1. So the shape of the field was found to be more influential. 3. Theoretical efficiency ηth was calculated by applying A, F and a, a/l to the 65 cases. The author measured the aberration ε between ηth and η, and calculated the theoretical aberiation εth by the regression line from A. As A becomes smaller, ε was proved to be larger, especially in irregular shaped field. 4. The difference of ε from εth might be called E, the difference of skill. The daviation of E was rather larger than expected, and moreover, it might be labelled as regional difference, individual difference and so on. The deviation of E was greator as A become smaller. 5. The value of η, under A, F and a, a/l, could be guessed, within the range of deviation of E, by calculating ηth and then by adding εth to it.
The auther has investigated the method which decides the economical service life of combine N0 best, and calculated the values of No best under various conditions. (1) The auther considered that the coefficient of the total expense of repairs ∑r was an exponential function of double correlation between a number of years N, and the total of used area ∑A. From this, the yearly average expense of repairs during the service life R was calculated. (2) The coefficient of average times for complete equipment t, and that of average expense of repairs r, could be considered to be under primary interrelations. The yearly average loss and gain of times to complete equipment S, may be calculated from this. (3) By using R and S, the calculating formula of yearly expenses of use Y(N) which was related to a number of years N and that of the economical service life N0 best could be determined. (4) When the coefficient of actual purchase expenses, g and A were 0 5, g0 and 30ha, respectively, the N0 best was equal to 9.4 years.
In order to find air resistance properties of chopped forage, apparent drag coefficients of stem particles were measured supporting them in a vertical wind tunnel. When the stem axis was supported parallel with the air stream, apparent drag coefficients decreased only slightly with an increase in Reynolde numbers. when a right angle was made between the stem axis and the air stream, they increased only slightly with an increase in Reynolde numbers. Supported in parallel, the apparent drag coefficient of the Orchard grass stem particles, 3mm in diameter and 20mm in length, was 0.689-1.138 (Re. No. 1.13×103-3.77×103), and supported at a right angle, it was 0.961-1.124 (Re. No. 5.8×102-1.94×103). Apparent drag coefficients increased as the length-to-diameter ratio of the stem increased.
Wafers of leguminous hay was made by continuous compressing and extrusing with a pair of dies and a piston, and the characteristics of wafers such as compressive force, change of density, falling shock durability and tensile strength were investigated. The results were as follows: 1. The apparatus was able to make wafers when the moisture content ranges of alfalfa and ladinoclover were about 13-55% and 17-35%, respectively. The collapse of these fibers grew when the moisture contents reduced and compressive stresses of alfalfa and ladinoclover reached approximately 830 and 500kg/cm2, respectively. 2. The maximum compressive force increased quickly as moisture contents decreased. It reduced when the hay was rewetted by water spraying after ground drying, however, the value was larger than that of ground dried hay if the moisture content was the same. In general, the maximum compressive force of alfalfa was larger than that of ladinoclover. 3. The equation expressing the selation between the compressive force and stroke curves was P=aebL where P=compressive force L=piston stroke a, b=constant and the compressive forces increased with the increase of compressive velocities, especially with dried hay. 4. The falling shock durability of wafers which had been dried to 12% moisture contents, generally, was smaller than that of before drying, and the durability became maximum when the forming moistures of the hay were each about 23-25%. 5. The tensile strength of wafers increased quickly as moisture contents decreased, and had not a direct relation with tensile strength of hay stems or falling durability of the wafer. Therefore, it was considered that the tensile strength of wafer was not a practical indicator for the durability of wafer. 6. In general, the densities of wetted or perfectly dried wafers and its magnifications increased quickly as the moisture contents of hay decreased. Therefore, they were not practical indications of durability of wafers just as the tensile strength was not. The magnifications of density of alfalfa and ladinoclover were about 25-45 and 18-45, respectively, and generally, the former was larger than the latter, and they increased with the decrease of moisture contents. 7. The useful wafer of leguminous hay could be easily formed at normal temperature by use of a die, 100mm long, 50mm wide and 12mm in thicknesses, and the most desirable moisture content was approximately 23-25%.
Using the experimental design analysis, the authors have studied the Water-Holding Capacity (W. H. C.) of thawed pork meat by varying the rate of freezing and thawing. The W. H. C. was measured by means of the conventional centrifugal method (1000G, 5min). The experimental temperatures were set up at -30, -50, -72°C for freezing, and 5, 8, 40, 60°C for thawing, respectively. The results were as follows. 1) ex, drip decreased as freezing rates increased. 2) The effect of final temperature on freezing appeared to be comparatively large, so the denaturation of pork meat increased notably over the merits of rapid freezing. 3) ex, drip decreased as thawing rates increased although the tendency was valid for a restricted range. The optimum rate was about 0.4°C/min in this study 4) The order of the effect on the W. H. C., was Main effect of freezing>Main effect of thawing>Interaction of freezing and thawing.