Vertical, horizontal and longitudinal displacement of three hitch points and three components of directional cosine of the hitch plane determined by right and left lower hitch points and top hitch point, which represent position and orientation of plow attached through a three points hitch system with position-controlled hydraulic device, are analytically derived concerning the two variables, using Cartesian co-ordinates fixed to a tractor. One variable is chosen as a deviated angle of lift arm m from horizontal plane and the other is angle of lateral displacement of left connecting rod or left lower link.
An example of electronic computation for Massey Ferguson FE-35 system is shown by the figures. In this example, computation is made for variable length of right connecting rod, and the depth and width deviation of plowing are shown to be restored by the change of pitch and yaw angles resulted from those devi-ations. When the reversible plow is used, rolling of plow is induced by the lateral displaceme, however, vertical displacement is nearly independent.

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Fundamental relationship among the side displacement, yaw angle, roll angle and induced vertical displacement of 3 points link hitch system is derived as functions of length of link members and relative position of hitch points. Depth change and resulted pitch angle variation of plow are also studied.
Lateral deformation of lower links due to side force acting on the plow brings about 7mm/200kg, for an example of Ferguson FE-35 tractor, so the corrections sre needed for geometrically determined position of hitch points. Other corrections due to elastic deformation are negligible.

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This paper presents the results of the theoretical and experimental investigation on the dynamic characteristics of the hydraulic mechanism with the overlapped directional control valve, under inertia and static friction loads.
The dynamic characteristics of this mechanism are expressed in the form of frequency characteristics. Then, the friction loads have much effect on the dynamic characteristics of this mechanism.

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Both the distance of futile run and the speed of tractor are important factors for the plowing capacity.
In the factors that are used to the calculation of the futile run, the width of plowing (b) controls directly the distance of running, and controls the number of turning indirectly.
The turning radious (r) changes by the wheelbase of tractor as shown in Tab. 1, and the former is proportional to the latter.
The distance of head land (L) is affected by the plowing and turning methods, and the maximum value arises in the Octopus type of S-turn, and the minimum value arises in the Popet and the Medusa type.
In these formula of calculation, we can understand that the number of turning is closely related to the distance of futile run.
(1) In the case of the S-turn, the distance of futile run and the number of turning has a relationship as shown in Fig. 2.
(2) In the case of the U-turn, if we devide the short side (B) into m parts, we get next formula: B/m-2r=bu,
In this formula, we understand if we want to decrease the number of turning (u) we must decrease m or b.
(3) In the case of E-turn, the formula is as follows:
4(πr+b)e=B/b⋅2πr+2B,
Therefore, to increase the plowing width (b) we must decrease the number of turning
In addition to this, there are next factors, that are excluding in the formula revealed the distance of futile run.
(4) The size of the field.
In the homologous rectangular field, the variation of the futile distance that is correspond to the area is shown in Fig. 3. Therefore, we see that the larger the field area, the better the plowing capacity.
(5) The slenderness rate of the field.
If the area is constant and the value of A/B is vatiable, we get the curve as shown in Fig. 4.
Therefore, we know that the larger the value of A/B, the better the efficiency.
(6) The shape of the field.
i) A parrallelogram
The number of turning is equivalent to the rectangle that has the same area and has same large side ‘A’. But in the case of U-turn, the number is increase as B=H/sinα⋅And the distance of head land is increase as 2rsin (90°-α)
ii) A triangle
In the case of continuous plowing method, the value of cycle number will be found by deviding the radius of circle that is inscribed to the triangle by width of plowing. But the distance of futile run is 4πr, which is constant value. Therefore the total of the distance of futile run is dependent on the cycle number.
Fig. 7. is the relation between the ratio of the radius of the inscribed circle (R) to the base (a) and the vertical angle of the triangle (Q). From this figure, we see that the value of an isoseles triangle is always maximum, but when a vertical angle changes in the range of 0°-180°, the value of R/a changes gently in the range of 1/2-0. And the smaller the vertical angle, the larger the value of R/a, and we can see the tendency that the decreasing rate is increasing.
iii) A sector
In using the continnous plowing method, the variation of the distance of futile run by a central angle is such that the futile run is maximum when the central angle is a little larger than 90°. But if the angle changes from the point, the value is reduced quadratically, and in the case of larger than 180°, the rate of decrease is gently, and is straight line.
iv) A segment of a circle
In using the continuous plowing method, the height of the shape is shown by next formula.
d=a/2⋅tanγ/2
We see that the smaller the ‘d’, the better the efficiency, as shown in Fig. 10.
v) A square
In using the continuous plowing method, we can calculate the number of cycles by the triangle that is circumscribed to the circle that is inscribed to the 3 sides of the square.

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It was confirmed by the last test that the cone penetrometer developed by the Waterways Experiment Station will be available to predict the trafficability of the tractors on the soft paddy field. So far, in our country, many same kinds of the cone panetrating devices has been used in agricultural field. Yamanaka's meter in Fig. 1 is the one of these soil hardness meters which was used mainly in the field of fertilizing improvement.
This test was attempted to know the relations of cone penetrometer and Yamanaka's meter and to find out whether the Yamanaka's meter will be available to predict the trafficability of the tractors or not.
The relations between the cone penetrating forces and the forces by Yamanaka's meter in kg/cm² and in kg/cm³ are presented by the broken curves C and D in Fig. 6. At the top layer of the soil surface, 0-10cm depth, the relation curve between the cone penetrating force in kg and Yamanaka's penetrating length in mm was similar to C or D curves, but in the deeper depth, the penetraing forces by cone increased as seen in Fig. 6, and the increasing rate of the forces to penetrate was the one kg. per five cm. It seems that the increasing of the penetrating force was due to the soil weight above that layer and friction force between the soil ahd penetrating rod.

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The power requirements (horizontal and vertical forces and torsional moment), travel speed, working depth, soil breaking and amount of soil rise on many models of subsoiler were determined in laboratory. The results were as follows:
(1) In general, the horizontal force of soil resistance to snbsoiler was about twice of downward force, and the resultant force was slightly larger than horizontal force, these three force increased with an increase in working depth.
(2) The direction of the resultant force was most influenced by cutting (oblique) angle, next was top angle and height of blade on the planetype subsoilers, but it was greatly influenced by the cutting width on the V-shaped snbsoilers. And in general, it was not almost influenced by the working depth, but increased slowly when the depth is over 20cm
(3) The elements of shape which have large effects on the horizontal and vertical forces were cutting angle and cutting width, but both forces were not almost influenced by the height of blade.
(4) The horizontal force was minimum and downward force scarcely increased when the cutting angle is about 20°, and hence in view of power requirements it was considered that this value is most desirable and the value of above 30° is undesirable.
(5) A small increase in horizontal and downward force occurred with an increase from 75mm to 125mm in height of blade.
(6) If the effect of soil surface rise or soil breaking was required, the increase of height of blade was most desirable because the horizontal force hardly increased.
(7) With an increase in cutting width of subsoiler, some increase in horizontal and downward force occurred, however the unit draft decreased.
(8) The both resistance forces scarcely increased with travel speed in the range of 0.2-0.7m/sec, and hence, high speed snbsoiling will be desirable from a view-point of the work efficiency.
(9) In clay loam, in general, both forces were greater, and soil crack was less and thicker than that in sandy loam.
(10) The amount of soil surface rise increased with an increase in cutting angle, height of blade, cutting width, and with a reduction of top angle. In general, the rise increased with working depth. However, on the subsoiler with large cutting angle or small cutting width, it was maximum at 15-20cm depth and reduced in more or less depth than that range.

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The power requirements, the amount of soil surface rise and soil breaking characteristics were determined in a wide variety of shapes, working depths, travel speeds and soils with models of sharped head type.
The composition of resistance forces were explained by analytical experiments such as the wedge-shaped head which was constructed with only upward or downward oblique plane or both planes. The results were as follows:
(1) The horizontal force reduced slightly and downward force increased with the height of blade in the case of only upward oblique plane. In the case of only downward oblique plane, however, the horizontal and upward forces increased considerablely, and this tendency increased with a decrease in the oblique angle, and hence, it is presumed that the more oblique angle reduce, the larger will be the influence due to the increase of mole-piercer diameter.
(2) In the case of symmetrical wedge with the same height of blade and the same section, the upward force and the tendency of refloating of blade increased with a decrease in the wedge angle, but horizontal force which was concerned directly to tractive resistance was not almost reduced.
(3) The power requirements due to the shank were very large, and all horizontal forces increased with working depth; on the other hand, the vertical forces showed a large variation, the upward force increased with an increase from negative value to 0°, and decreased with an increase from 0°to about 30°in the shank angle, and it changed to downward force at near 30°, and increased greatly with an increase in the positive shank angle.
(4) In the event of only upward oblique plane or synmetrical wedge, the amount of soil surface rise increased with the height of blade and the wedge angle, and the amount was numerous at deep and reduced at shallow; in the case of only downward oblique plane, it increased especially at deep with a decrease in the height of blade at the same downward oblique angle, and with an increase in downward oblique angle at the same height of blade.
(5) The center of resistance was situated on near the sharped head. The both forces increased slightly with travel speed; the conditions of soil breaking and the amount of rise were not almost changed by the change of travel speed or kind of soil.

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The action forces on model mole Piercers (the ball type), when they pierce through the sandy loam and clay loam was measured. The results were as follows.
(1) In the case of deep penetrating, the horizontal forces of the ball whose extreme angle is 30 degrees are smaller than the ones whose extreme angles are 45 and 60 degrees respectively.
But when they pierce through shallow layer and have long skirt, there is not any difference of the horizontal forces between the small and the large angled ball.
(2) Large downward force acts upon the small angled ball, and this tendency is remarkable as skirt length increases. Upward force acts on the balls of 45 and 60 degrees when the skirts are short or nothing.
(3) The compound force on the ball is the largest when extreme angle is 30 degrees, and is the smallest when it is 45 degrees.
(4) On the clay loam, the upward force and the horizontal force increase, when compared with that on sandy loam. But it seems that whole tendency is the same both at clay and sandy loam.
(5) It appears that the horizontal force increases in proprotion to the diameter of ball.
(6) The horizontal action force incleases when the pierce speed exceeds 0.37m/s, but the vertical action force has nothing to do with pierce speed.

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The adaptability of tractor-mounted sprayer to the rice paddy field was studied. In the case of tractor running spray by the boom-type nozzle in the field, the mechanical damage of the rice plant was neglectible small and the pest control effect was no less than the standard method. In another case by gun-type nozzle from outside of the field (on the road), the effect was limited to 15m in the distance of spray deposited. The relation between the condition of the road or the field of tractor running and its over-turnning angle of spray-mounted tractor was studied, too.

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Based on authors' previous report, two equations were presented to look for such a size of a combine as minimize work cost with correlation to annual harvesting area.
1. Cost of harvesting per hectare (C yen) can be calculated from the next equation.
C=10L/SWE+10f/SE+fcPW/A+YV
{a/2(10A/hSWE-1)+b}
where L=labour cost per hour (yen)
S=theoretical forward speed of combine (km/hr)
W=cutting width of cutterbar (m)
E=field efficiency
f=fuel and lubricant cost per 1 meter of cutterbar (yen/hr)
fc=annual fixed cost ratio of combine (according to straight line method)
P=price of combine per 1 meter of cutterbar (yen)
A=annual harvesting area (ha)
Y=yield of rice (kg/ha)
V=sales price of rice (yen/kg)
a=increasing field loss ratio per one day delay after most adequate harvest time
b=field loss ratio at most adequate harvest time (coefficient a and b are 0.004 and 0.05 respectively from authors' previous report.)
2. Functional relations among A, W and C are presented in Fig, 3 and 4. As these figures show, each cost curved line has a minimum point. This point is minimum cost harvesting area for each size of a combine, or minimum cost size for each area.
3. From differential calculus of above epuation, there should exist following relation between A and W to minimize work cost per hectare.
W=√5(2hLA+aVYA²)/fchEPS

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The present test was continued from the test in 1961, and the results of the test were similar to that of the hay dryer test summarized on p. 133, Vol. XXIV, No. 3 of this journal. Some of the results can be analyzed as follows:
(1) For the first grass, the total operating time of the blower was 178 hours to reduce the water content in 16 tons of hay from 25-30% to 15-20%. In this case, the electric power consumption was 984KWH to remove 1.9 tons of water.
(2) For the second grass, the total actual operating time and electric power consumption were 118hr and 812.5KWH, respectively, to remove 5 tons of water from 6 tons of the baled hay with 35% water content. For 10.1 tons of the low density baled hay with 30% water content, the above mentioned values to extract 1.8 tons of water were 50hr and 344KWH.
(3) The above mentioned time are actual operating hours of the blower, and the blower was run only in the daytime. Therefore, two or three weeks should be considered to finish the hay drying.
(4) It can be expected that the drying effect for the hay, baled as loose as possible with the common baler, is not so different for the bale with the low density baler.
(5) When the risk of temperature rise of the hay is considered, the blower must be run, even though the humidity in the air is too high for drying the hay.

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