Some properties of friction and wear of Al-base bearing alloys under dry or wet condition were investigated. The results of this investigation were as follows : (1) Under dry condition : When the speed was low, the rates of increase of wear decreased with the increase of load. But when the speed became high, the wear increased rapidly with the load beyond a certain amount of load. The wear decreased with the increase of speed to a certain minimum value and the speed at which the wear was minimum, became low as the load increased, and this tendency was conspicuous with AlJ1. (2) Under wet condition : The wear decreased generally with the increases of load and speed. When AlJ1 was used, this decrease was larger. The coefficient of friction of AlJ1 increased rapidly with the decrease of Zn/P below a value of Zn/P where the coefficient of friction showed a minimum value. Under a certain load, the coefficient of friction was almost constant regardless of the speed with every alloy.

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A dimensional analysis is carried out for a simple sliding wear under dry and steady state, based on the experimental evidences reported by G. Hughes and R. T. Spurr (1955), and K. J. Trigger and B. T. Chao (1956). Applying the analysis to several experimental data on wear, a simple theory is derived, that is, the rate of wear per unit normal pressure and sliding distance is a function of dimensionless numbers containing pv and v, where p and v denote normal pressure and sliding speed respectively. And it is shown that this fact coincides with Holm's theory.

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The handling capacity of a vertical bucket grain elevator of centrifugal discharge type, which was deficient owing to the low discharge efficiency, was considerably improved by changing the shape of the bucket. Further researches on the behavior of grain during discharge were carried out on a model equipment and the following results were obtained. In regard to the discharge efficiency the bottom and top angles of the bucket are essential factors and those exceeding 25°and 70°respectively seem to be more favorable. If the bottom angle is smaller than 25°, some part of the grain falls without reaching the chute ; if the top angle is smaller than 70°, some quantity overflows before the bucket arrives at the top position. Most of the grain discharged passes closely over the bucket edge in an approximately parabolic motion with an initial velocity nearly equal to the circumferential velocity of the edge.

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Investigations concerning cavitation in several impellers with three dimensional blades were carried out using a 200 mm bore single suction pump installed in a closed circuit system. Flow inside the impeller was observed with strobo-light, and the NPSH at the condition of cavitation incipience measured for each impeller was found to show a peculiar variation against capacity taking a minimum at or near the designed flow rate and a peak at a partial capacity. The flow at the impeller inlet was measured with a Pitot tube and it was clarified that the flow pattern which accompanied remarkable swirling and back flow at partial capacities was responsible for the above NPSH variation. The cavitation aspects in the impellers are presented by photographs and their correlations with the various local pressure drops are discussed. The impellers were compared in terms of pressure drop coefficients as well as the suction specific speed plotted versus capacities with a view to applying them to the practical fields.

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The flow behaviours of the flow field in a impeller and guide vane of axial blower have been observed using the technique of visualization by silk tufts. When the stall zone is limited to the tip region only, the surging zone on the ψ-φ characteristics does not appear clearly. Therefore, if the suction or delivery concentric rings have the effect to prevent the stall zone from extending toward the section within geometrical mean radius, the stall characteristics of an axial machine will be improved. In the stationary guide vane of an axial blower, the blade characteristics are better than those of other section, owing to the flow in the boundary layer from tip to root caused by a secondary flow in the curved channel.

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Vickers hardness numbers of 45 test specimens have been measured by 4 pyramidal indenters with different magnitudes of face angles (angles between opposite faces of pyramids), in order to find the relation between the Vickers hardness numbers Hv and the magnitudes of the face angles θ. Then, this relation was formulated in a mathematical form, in which the mean pressure, i.e. Hv/sinθ/2 was represented by the experimental function of tan θ/2. This is the same as the result already obtained by one of the authors in the measurement with pyramidal indenters of tungsten carbide. In the present experiment, it has been found that the value of the exponent for each specimen depends on its material ranging 0.15∼0.40 and is in a simple relation with the hardness of the test specimen. From this result, it can be expected that the maximum error in the Vickers hardness number measured will not exceed 0.2∼0.5%, if pyramidal indenters of face angles of 136°±0.5°are used. The experimental formula for the mean pressure may also be expressed by the experimental function of cosθ/2 instead of tan θ/2, in which case the value of the exponent for each specimen depends on the work-hardening characteristics of its material.

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A new hypothesis for formation of non-propagating cracks under fatigue of metals is proposed. The hypothesis is based on coaxing effect and strain hardening effect and others, which the related material receives at the tip of a fatigue crack. Due to these effect, the material at the tip of fatigue crack is considered to be stronger at inner parts than at near surface. The fatigue strength for formation of cracks and that for destruction are considered. A critical value of the fatigue strength reduction factor, which means the minimum value of it for formation of non-propagating crack, is also considered. The relation between the critical fatigue strength reduction factor and the fatigue strength of two kinds above mentioned is obtained from the hypothesis proposed. The reduced relations are compared with the results of experiments made on rotating bending and repeated torsion, and a good agreement is noticed.

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In the previous paper, the author proved that the exact solutions of stress distributions and displacements on the free surface of semi-infinite elastic solid indented with a rigid sphere are obtained applying the Hankel transforms, and that the approximate solutions under the influence of friction on the contact surface are deduced by the suitable use of above solutions. In the present paper, the stress distributions at an interior part of the medium are given. As an example, the variation of the maximum shearing stress τ under the influence of friction for the different values of ν (Poisson's ratio) is shown, and lastly the above results are discussed by means of two-dimensional photoelastic test.

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Let σ₁, σ₂ and σ₃ (σ₁>σ₂>σ₃) be the principal stresses, and σ₃=0. Taking σ₁ and σ₂ as the axes, the criterion of plastic flow is not expressed by a smooth curve by the authors' theory, but a curve composed of two straight lines which intersect at σ₁=4σ₂ in the range between tension and pure shear. Experiments were carried out. The results show that there is an abrupt bent as expected according to the authors' theory.

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Aiming at the design of a structure under random loading, e.g. a tail of airplane in flight through a three-dimensional turbulence, the mean square values of deflections and stresses are evaluated by a stochastic method on the basis of simplified representations of the structure with finite span and its spanwise lift distribution. In this analysis the typical power-spectrum of stationary isotropic three-dimensional turbulence is used, and it is assumed that the scale of turbulence is much smaller than the length of span, and that the intensity of turbulence is so small that a stall does not occur. It is well-known that the variance of stress is used in estimating the strength and fatigue life.

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In this paper, a three-dimensional solution for an infinite plate with a cylindrical circular hole under transverse bending is given. It is represented by a combination of the solution which is regular in the outside of a hole and the solution which is regular in the infinite plate with finite thickness, and satisfies the boundary conditions on the surface of the hole and the surfaces of the plate. Numerical results are given when the ratios of hole diameter 2a to plate thickness 2h are about 0.3, 1, and 3. The results show that the smaller a/h becomes, the larger the stress-concentration factor becomes as compared with the value obtained by the theory of thin plates, and the more the circumferential stress across the thickness of the plate at the ends of diameter parallel to the axis of the applied bending moment deviates from a linear distribution.

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By extending M.A. Biot's method, the author calculated the local compressive stress distribution in the web of a grider, when a wheel load was applied on a rail resting on the top of the girder on a rigid foundation. Experiments were carried out, when a girder was rested on a rigid foundation and supported on two points. Both results have shown a satisfactory agreement with the calculated values. Therefore, it may be concluded that the distribution of the local stress is scarcely dependent on a span.

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Fatigue tests of carbon steels were carried out at 550°C under rotating bending and also under repeated torsion in town gas to reduce air oxidation, as a first step to study the effects of atmosphere on fatigue strengths at elevated temperatures. For long lives under low stresses, the strength was higher in gas than in air, and the influence of corrosion fatigue due to oxidation was found in air at high temperature. Meanwhile the strength was lower in gas than in air for short lives under high stresses, and the S-N curves in air and in gas cross each other. This may be attributed to the hydrogen embrittlement resulting from the decomposition of water vapor. The S-N curve at elevated temperatures may take a considerably different shape if the effects of oxidation by air are removed, and its slope becomes more gentle after a long time.

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When small induction motors equipped with rolling bearings are running under no load, abnormal axial vibrations of a rotating shaft appear often, and especially most frequently in the case of single row ball bearings. In addition to the vibrations, a kind of humming noise grows. The authors analyzed these phenomena and obtained certain results as follows : (1) The axial vibration is a free vibration of a system composed of a rotating mass of rotor and a non-linear spring for axial direction of ball bearings. In this spring character, two kinds of region exist, one is symmetric, the other asymmetric. (2) The frequency of the vibration in the symmetrical non-linear spring region can be calculated on the basis of the theory of elasticity and non-linear vibration. (3) The humming noise grows when the bending natural frequency of brackets is j/2 times of that of the vibration (j is a positive integer), and these cases correspond to the unstable region in Mathieu's vibratory system.

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In vibratory machineries electro-magnetic vibrators are frequently used as the source of vibration. These vibrators for practical use are of moving-coil or electro-magnet type and are excited with sinusoidal or half-wave rectified current. In order to investigate the fundamental performance of vibratory machineries, the steady state motion of vibrators and that of an ideal vibratory machine with two degrees of freedom system are analysed by an approximate method. The performance obtained from this analysis is found to agree well with the experimental results.

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The deflection curve of the center line of coiled springs is discussed, expanding the Bernoulli-Euler equation for the elastica of thin rods. Numerical results and their comparison to the experimental values are presented.

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The phenomenon of blow-by in internal combustion engines has an important effect upon engine performance, the lubrication of cylinder wall, the oxidation of engine oil, and the bearing temperature, causing deterioration in the durability of the engine. The object of our experiments is to clarify the phenomenon of blow-by and its influence upon the piston and piston ring dimensions and the running condition of our automobile engine. The conditions of piston, piston rings and cylinder liner that give the best performance and the minimum rate of blow-by in our Automotive Gasoline Engine are shown in these papers.

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The results of tests on fourteen boilers conducted by the ASME Research Committee and one boiler in Japan are analyzed in this paper to find the area ratios, accordingly the volume ratios of flame to furnace. The volume ratio is less than 0.2 in most cases and is about 0.25 even in the extreme case, when 0.8 m^-1 is used as the coefficient of absorption in the flame of coal and heavy oil and 0.25 m^-1 in the flame of natural gas and when a mean flame temperature is assumed as 1/2 (adiabatic flame temperature+furnace exit gas temperature). So the frequency distribution of the heat-flow intensity on the walls irradiated by a uniform flame surrounded by transparent gas, as shown in the first report, coincides closely with that by the actual flame. The value of the ratio can be determined as a function of combustion intensity in each firing system with a burner of horizontal type, vertical type or tangential type (coalor oil-fired), a horizontal type (gas-fired), a stoker and a spreader-stoker.

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The heat transfer by the convection in the annular gap between the rotating inner cylinder and the stationary outer cylinder was measured in the air, spindle oil and mobile oil at varying rotational speeds, cylinder diameters and widths of gap. The results show that characteristics of the flow and heat transfer have two modes. If the rotational speed is low and the width of gap is narrow, namely (vδ/ν)√(δ/γ)<41, the flow is laminar and the heat is transferred by conduction and radiation. But if (vδ/ν)√(δ/γ)<41, the rate of heat transfer increases with rotational speeds under the influence of secondary vortices induced by the centrifugal force, which may be given by Uδ/λ=0.21 ((v²δ²)/(ν²)·δ/γ·P_γ)^1/4 where U denotes the overall coefficient of heat transfer through the gap, δ the width of the gap, λ the thermal conductivity, ν the kinematic viscosity and Pr the Prandtl Number, γ and ν the radius and the peripheral velocity of the rotating cylinder respectively.

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Regarding the penetrating distance of fuel spray in a diesel engine, the old theory dealing with the motion of a fuel droplet in still air is recognized not to coincide with the actual phenomenon in a diesel engine because of the extremely small size of atomized fuel droplets and the very high density of gas in cylinder. In this paper, the characteristics of spray penetration are discussed from the viewpoint of momentum theory based on the idea that the air induced into a fuel jet stream makes a kind of mixed gas together with fuel droplets. According to the results of experiment, the authors confirmed that the theory was satisfactory, that there existed the simple relations among several dimensionless numbers which indicate the effect of various factors on the spray penetration, that there is a close relationship between the spray cone angle and penetration, and others.

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One of the important problems involved in the design of the port arrangement of a through scavenged 2-stroke Diesel engine is that of determining the entry angle of inlet ports. This paper presents the results investigated the effect of port-angle on the scavenging process inside the cylinder by using a new electronic method in model cylinders of a through scavenging system.

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To examine the effects of length of an intake pipe on the delivery ratio (or the breathing capacity) in a small crankcase-scavenged type two-stroke cycle engine, the authors have measured the amount of air flow and analyzed some pressure indicator diagrams for the intake pipe, the crankcase and the cylinder. Some conclusions obtained are summarized as follows : a) The maximum delivery ratio occurs on account of the inertia-effect same as in the case of four-stroke engine and the matching conditions for the inertia-effect are expressed by Z_M=ωL^*/a_s&cong;θ_s/270. b) In the special cases of a long intake pipe or high speed, the pulsation waves in the intake pipe have an influence on the delivery ratio and such pulsation effect is governed by q=15a_s/(N·L_s). c) Comparing these equations, it may be noted that the inertia-effect differs essentially from the pulsation-effect.

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In the previous experiments⁽1) with a small two-stroke cycle engine, the authors found that as a carburetor was put near an inlet port, the combustion in the cylinder became worse. In order to examine the effect of the position of a carburetor on the engine combustion, they carried out systematically some experiments with an intake pipe of constant length. The results obtained are summarized as follows : a) In general, the nearer the carburetor approaches the inlet port, the worse the combustion becomes. b) With an intake pipe of constant length, the delivery ratio is scarcely affected by the position of a carburetor in the intake pipe system, but the fuel consumption varies extensively by the position of it. c) The poor combustion or mis-firing is caused by the lack of fuel, which is partly governed by the matching condition q and depends largely on the amplitude of pulsation wave that increases with the engine speed and the approaching of carburetor to the inlet port.

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Compression ratio of Otto engine can be increased by injecting fuel into the combustion chamber shortly before the spark occurs. However, if the fuel is injected too late, it can not be evaporated and mixed with the air rapidly enough to make it undergo perfect combustion. The performances with the testing engine-the uniflow type crankcase compression, twostroke-cycle gasoline injection engine-were measured at the various injection timings without throttling air just as a Diesel engine. At the retarded injection with 51 octane gasoline, the maximum mean effective pressure was 5.4kg/cm² and the minimum specific fuel consumption was 240 g/HP/hr. However, at the advanced injection, knock occurred under heavy loads, and at an intermediate timing between the two, the ignition failed to take place at light loads.

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In the cylinder injection engine, for example, the Texaco Combustion Engine, the continuous ignition source was required in order to get knock-free combustion with the stationary flame front, as already reported in the previous paper⁽1). An electrically heated hot spot in the combustion chamber, named "Heat Plug", was utilized as a continuous ignition source. Following experiments-on the relations between temperature of heated surface and ignition lags of fuels, photographic study of ignition and also combustion by a heat plug-were made. In addition, the performances of the two-stroke-cycle gasoline engine ignited by the heat plug were measured, running with gasoline and Diesel light oil.

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In this paper the authors have described the results of measuring the temperature distribution over the usual piston, special piston, and cylinder liner by means of the thermocouples, and the results of calculating the heat transmitted from the piston to the cylinder liner. The special piston has four or six longitudinal fins which are installed inside with intension to decrease the temperature of both the piston head and the first ring groove. From the experimental results, the following conclusions were reached. (a) The temperature of usual piston without fins is so high that the first ring of piston is in danger of sticking. On the contrary the longitudinal fins of inside surface prove effective as intended by the authors. (b) The exhaust gas leakage disturbs the concentric uniformity of the temperature of the piston body. (c) The heat is transferred to the air in the crank case from the inner surface of the tail part of liner. (d) The overall coefficient of heat transmission from the piston body to the liner through the piston rings is calculated to be 7000 to 8000 kcal/m²hr°C.

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Previously the synthesis of the 4-bar linkage has been carried out by using Mittelpunkt-Kurve and Kreispunki-Kurve⁽1) or their particular solutions⁽2), but these methods are very difficult, and need many hours, to apply in addition to their being inaccurate. In this paper, the locus of a point on the connecting rod has been described systematically in a wide range of the linkage dimensions. It is found that these curves can be classified into several types according to their distortion and undulation, and that the rotating centre of the driving crank falls on a solid intersection nomogram which gives the length r of the driving crank and the coordinate of a point on the connecting rod. As a result, we can obtain a more rapid synthesis of the 4-bar linkage with higher accuracy than was given by the conventional methods, and the new method will also make it easier to obtain that of the 6-bar linkage.

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