Many experiments of relations between tractive force, tractive horse power, tractive efficiency and slippage of tractor rigid wheels are reported. But few of these relations are explained theoretically.
Some qualitative explanations are tried on these relations, supposing tractive forces of a tractor depend on slippage of driving wheels.
(1) Tangential component v_t and horizontal component v_h of peripheral velocity v₀ at any point of a wheel may be written as follows (Fig. 1),
v_t=v₀-vcosρ
v_h=v₀cosρ-v
Average values of v_t and v_h along contact part of the wheel with soil, v_t and v_h, are calculated. Then it is assumed that brake force N_t at the driving wheel is proportional to v_tⁿ and tractive force N_h is proportional to v_hⁿ.
N_t=kv₀ⁿ(bS+a)ⁿ……(3)
N_h=kv₀ⁿ(S-a)ⁿ……(4)
a=(α-sinα)/α, b=sinα/α
where S is slippage of the wheel. From these equations many relations are deduced as follows. (2) Equation (4) indicates that tractive force increases as slippage increases, as shown in many experiments of literature 4), 5), 6).(Fig 2-a)
(3) The relation between tractive horse power H and slippage is,
H=k/75v₀ⁿ⁺¹(S-a)ⁿ(1-S)……(5)
From equation (8), the maximum value of tractive horse power H about slippage will exist, as shown experimentally in literature 7), 8). (Fig 2-b)
(4) The tractive horse power is expressed in other form concerning tractive force;
H=v₀/75N_h{1-a-1/v₀(N_h/k)^1/n}……(7)
A tendency of relation between H and N_h is shown as Fig. 2-C, and an experiment in literature 9) may be explained by equation (7).
(5) Brake horse power is from equation (3),
L=k/75v₀ⁿ⁺¹(bS+a)ⁿ
Therefore tractive efficiency is;
η=H/L=(S-a/bS+a)ⁿ(1-S)……(8)
Efficiency η is 0 at S=1 and η may be the highest near S=0. Thus η decreases as S increases, as shown in literature 10). (Fig. 2-d)
(6) Tractive efficiency η is noted in other form concerning tractive force N_h,
η=N_h/N_t{1-a-1/v₀(N_h/k)^1/n}……(9)
From this equation there is the maximum value of η, as shown in literature 9), 11). (Fig. 2-e)

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Any tractor does not always travel the same direction as it's wheels revolve. Especially on the hilly land, the wheels must be kept to have the upper deflection angle for the contour line not to slip down. This report is the experimental results of the running resistances of wheels having the deflection angle (α).
On the case of pulling the tractor with another one, traction force needed—traction resistance—is expressed in form of eq. (1), and the side force (Sr) is in form of eq. (2), which obtained in the cause of the revolution of wheels.
D=K₁Wsinα (1)
Sr=K₂WsinAα^1/B (2)
Where, W is the weight of tractor.
K₁ and K₂ are the coefficients. Those are not variable by the size and load of the tires, but variable by the road conditon.
When the test tractor drives by himself pulling some of loads (P), the maximum traction force (P_max) and the side force (S_p(n)) are expressed in form of eq. (3) and (4) respectively.
P_max=K₃Wcosα (3)
S_p(n)=K₄Wsinα+Sr(1-P/P_max)(1-α/90) (4)
Where, K₃ and K₄ are the coefficients having the same characters of K₁ and K₂.
The force ratios on the each load for traveling direction were the minimum values in 30-40 degrees of the deflection angle, and the larger the traction force were, the higher they were. On the other hand, the side force ratios were higher for the smaller traction forces and the smaller deflection angles, and the larger the traction forces and deflection angles were, the less they were.
The traction efficiency was maximum value for about 0.3 in the coefficient of traction at 0 degree of the deflection angle.
As the running resistance of wheels, having the deflection angle, were larger and the traction efficincies were lower like above than we supposed, many effective studies concerning with the better design of wheels, the better using and improvement of tractors and others are expected to reduce the value of the deflection angle.

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(1) The tests were carried out to clarify the influences of field conditions to the drawbar pull and trafficabilities on soft reclaimed field in a region of Lake-Biwako in Shiga prefecture on July 1965. Three crawler tractors equipped with 300, 400 and 500mm width of track shoes respectively, a four wheel tractor and a Japanese small power tiller with rubber track shoes were used.
(2) The test field was so soft that Soil Values Meter TN-4 had no penetrating resistance within the depth of 20cm. As the results of measuring the shearing stress of soil by TN-4, angle of internal friction was 15°-25° and cohesion c was 0.08-0.12kg/cm² for undisturbed soils, but as to the disturbed soils passed over by wheels of tractors, was almost zero.
(3) The mean value of coefficient of traction of crawler tractors was 0.585 at 100 percent slippage and within the trafficable limits, it was 0.52 at 20 percent slippage. Running resistances of them were nearly proportional to their sinkage, that is, 500kg at 6cm sinkage, 1200kg at 15cm and at 17cm sinkage they could not move. The rate of running resistances to weights of tractors when they lost its running abilities was found to be 0.65.
(4) On turning, the sinkage of the inner track shoe was 1.3-1.4 times deeper than that of the outer one, but there were little differences of sinkage by the length of turning radius.
(5) A single moldboard 40cm plow was used to the plowing test in the mean depth of 22.4cm and the speed of 0.55m/s. when both track shoes were on the unplowed land, 3 percent slippage was found, but when the right ran in a furrow, there arose a difference of slippage between the right track shoe (19 percent) and the left (2 percent).
(6) The critical soil hardness at which each tractor could run was measured by TN-4. As for the tractor equipped with 300mm width of track shoes, it was 6-7kg in the penetrating resistance (with the own weight of TN-4), with 400mm width 4.5-6kg and with 500mm width 3.5-4.5kg. These values coincide well to the estimated one from V. C. I.. Tractors could not run under the conditions of above 20 percent slippage or 0.52 coefficient of traction when loaded. Furthermore, they could not move forward at all in the time of transportation with a mounted plow. The sinkage of the semi-crawler tractor with half-track shoes—specially that of the front wheel was deeper than the estimated sinkage from V. C. I.. Then, it is necessary to take larger value from V. C. I. in case of prediction of the trafficabilities of semi-crawler tractors.
(7) The estimated driving power from the contact area of track shoe, weight of tractor, field conditions etc., nearly coincide to the actually measured one. The drawbar pulls obtained in the plowing tests were only 1/6-1/8 times of those in the simple drawbar pull tests, and above that drawbar pull, the tractors could not move.

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We made rotary-plowing by tractors in table 1, table 2 indicates turning time which effects efficiency, and in direct plowing it does little more than calculative value, while in rotational plowing little less.
It is thinkable of this difference than standard of calculations was taken at directly under the rear wheel, but in actual working directly under the work machine.
Every tractor indicated maximum in alternated plowing method, second in succesible plowing method and third in rotational plowing method by efficiciency curve on three plowing methods in figure 1. And on type of tractors, A-tractor which has few turning time is great, B-tractor comes after and C-tractor is least.
Figure 2 is the capacity curve of multiplying plowing width and plowing speed by these efficiency value. On the plowing method, each tractor has a tendency to bear a resemblance to the efficiency like indication of the figure, which type of tractors, C-tractor which has lowest efficiency has best field capacity, and A-tractor which has highest efficiency has least. In brief, the capacity will have much influenced because the varience of plowing width is more than efficiency.
Next, the value of capacity of B-tractor compared with plow-plowing is indicated in table 3. We judge by this table that rotary-plowing is superior to in alternated plowing method, and in rotational plowing method, plow-plowing is slightly better.
In the last analysis, development of plowing capacity and reduction of working time need the large sized tractor of powerful HP and use it which plowing width is increased, more over it is good to manage the field by alternated plowing method.

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In regard th promoting the faculty of “Sliling-vane rotating pump” with impeller made of synthetic rubber, some experiments were conducted and the following results were obtained.
1) The best result was obtained as shown in fig. 2 by use of cam 4/3 compared with other size of cam in fig. 1.
2) Shaft horse power of pump increased with the decrease of side-clearance between impeller and side-wall.
The value of side-clearance of 0-0.3mm is recommened due to the result of fig. 3 (1).
3) The time lag of water flow at the delivery of pump immediately after switched in, prolonged with the increase of side-clearance.
Allowable value of side-clearance was expressed on this point of vien.
4) The influences of the degree of blockage of strainer upon the perforance of pump were expressed in fig. 6.
5) The remarkable abrasion of parts and fall of efficiency did not occur after the running test of 100 to 200 hours. (cf. fig. 7. 8)
6) The occurrence of foaming inside of casing was observed by using Stroboscope method.

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The power requirements of the small header combine were measured in rice field. The results were as follows.
1). Power requirements of cylinder and 2nd blower were affected by the flow rate of straw and grain.
2). The allowable flow rate for this combine was about 16-17kg/min.
3). The power distribution for combining rice were,
(1) Power of cylinder takes about 15-16 percent of the engine output.
(2) Powers of remaining stalk cutter and 2nd blower take respectively about 14-18 percent of the engine output.
(3) Powers of cutter and wheel take respectively about 8-10 percent and 6-8 percent of the engine output.

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There are considerable injured grains, such as opening glume, cracked glume and hasked rice in the rough rices harvested by the combine. Consequently, the drying speed of rough rice is increased and the problem of the occurrence of cracked rice is come of.
To investigate this problem, the rough rice was impacted by a grain impact testing machine, and the following results were obtained as to occurrence of injured grain, cracked rice and drying characteristic.
(1) The injury of rough rice by the impact is rapidly increased from the impacting speed of about 1, 250m/min. and the correlation between the percent of injury (y₁) and the impact speed (x₁) can be expressed by the following equation: y₁=Cx₁^α, where C and α are constants due to rough rice. But the increase of occurrence of cracked rice is comparatively slack.
(2) The influence of ripeness extent and moisture content to the impact was not recognized as to the rough rice of more than 35 days after heading and so far as the moisture contents are 21-25%.
(3) The more the impacting force increased, the faster the drying speed of impacted rough rice. This proves that the rough rice became easy to dry since the rough rice was injured. The correlation between the change of moisture content (y₂) and the passage of drying time (x₂) can be expressed by the following equation; y₂=Dx₂β, where D and β are constants depend on moisture content of rough rice, impacting speed and condition of drying air. (2<x₂<6 hours)
(4) The injured rough rice not only hastens the drying in proportion to the impacting speed, but also leads to the increase of occurrence of the cracked rice.
As the cracked rice is increased at the speed of impact more than 1, 250m/min., it is necessary to down the drying speed against the rough rices which have the occurrence of many injured grains.

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When the grain is dropping in an air turbulent flow path at separation point, the author studied the representation of grain stream.
In order to decide the wind velocity of neighbourhood of grain at the minimum stream section, the representative function was decided by S. C. Transformation about two grains—one was on the datum line and the other flowed down formerly and was the constant position away from one. The projection was decided to make a real plane and the parameter plane according to a conformal representation, and the closed polygon in conformity with a force line shaft was made. Then the displacement on a real plane was calculated by the theorem of a regular function and method of S. C. Transformation, since then divided the real part and the imaginary part.
As the result, the stream force line was granted that grains were threw in the pneumatic grain separation path with winnower to separate, it was decided that the extension of turbulent flow did not ended in stronger, and the equi-potential flow line was similar also.

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The flail mower is the machine that cuts and cracks the grass by the hinged flails in one operation with one power driven part. It is like the flail type forage harvester, however its rotor speed is lower than the forage harvester. Relations between the rotor speed and PTO torque, length of cut, height of cut were tested in the fields. And the drying rate of grass on the field by the use of flail mower was compared with the use of cutter-bar mower and hay conditioner. The cut width of the tested flail mower was 6ft. The results were as follows.
(1) Increasing the rotor speed and travel speed the PTO torque increased. The fluctuation of the torque was very intense. Tractor power required 40h. p. at travel speed 1.3m/s. Then the rate of working of this machine would be 0.6-0.8ha/hr.
(2) The length of cut was the longest at the rotor speed 700-900rpm and no significant difference of the length of cut between the use of flail mower and the hay conditioner was observed.
(3) The field curing period by the use of flail mower was shorter than by the use of hay conditioner.

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For the fundamental studies of the hay wafer, compression tests were done and the mechanical characteristics of the grasses, such as their frictional coefficients, moment of flection and flexural rigidity were investigated. Wafers for this investigation were made in cylinder and pistion-type compression chamber.
1) Increasing the moisture content of the plant gave an increase in the coefficient of friction and the moment of flection. The flexural rigidities were minimum between 40-60 percent water content, wet basis (wb).
2) The pressure of piston can be represented with following equations.
p_k=a⋅exp⋅bs^m p_k=α⋅exp⋅βρⁿ
where, s=piston displacement, ρ=density of wafer, the others=constants.
3) The solidity of wafer is good as the flexural rigidity and the moment of flection decrease, but it is not good as they are too small.
4) At high moisture content, water is compressed out, and the solidity of wafer after releasing the pressure is bad. The moisture content for good solidity of wafer is different on the plants.
5) The handling durability of the short cutted, material and chaffs were very bad. This is probably due to the non-existence of interlocking fibers in the wafer.
6) Increasing the pressure gave good solidity.
7) By allowing the wafers to stand for long time after releasing the pressure, the expansion became insignificant but the rate of expansion was great just after releasing the pressure. The rate of expansion decreased as the sample volume increased.

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The investigation of behaviour of an ejector feeder conveying air alone suggested that
(i) the loss at the ejector increases with decrease of the opening ratio and approaches a constant value as the opening ratio continues to increase, and the pressure at the feed chamber decreases rapidly with increase of the opening ratio and thereafter increases with increasing the opening ratio,
(ii) the jet length is likely to have little effect on the characteristics of the ejector,
(iii) efficiency of the diffuser shows a maximum value at degree of 8,
(iv) the back—pressure of ejector is likely to have little effect on the loss of the ejector, however, the pressure at the feed chamber increases with increase of the back-pressure, and
(v) the pressure at the feed chamber decreases with increase of air rate, while there may be a limit of air rate because air velocity for conveying solids is not excessively high.

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