Lateral vibrations of rotating shaft are recorded, and response curves of sub-harmonic and "summed and differential harmonic" oscillations are experimentally obtained. Summarizing, the amplitudes of sub-harmonic oscillation of 1/2 order increase with the magnitudes of eccentricity of rotating body. Shapes of response curves of sub-harmonic oscillations of forward precession are those of hard spring type, and the response curves of soft spring type are obtained for backward precessional whirling motions. For one critical speed of "summed and differential harmonic" oscillations, the height of peak decreases as eccentricity increases. The other critical speeds have a constant amplitude, even if the magnitude of eccentricity is changed. Shapes of response curves of "summed and differential harmonic" oscillations are either discontinuous response curves with jump phenomena or continuous, as the nonlinear spring characteristics of shaft are changed.

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In this report, we treated the stiffness of bellows type air springs, introducing volumetric effective area A_v, pressure effective area A_p and several coefficients which are determined by bellows form ; obtained the formulas of stiffness, inner pressure and load ; calculated the shape coefficients of various types of tire type bellows and made clear the conditions under which the stiffness is small. The results applied to air springs for railway cars and models of air springs show close agreement with experimental data.

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Flat bar specimens of Phenolite with V-notches on both edges were subjected to pure bending and the stress concentration factors under various conditions were measured by the photoelastic method. To determine the fringe orders at the base of notch, several bending moments were applied. Similar to the experimental results in tension, the stress concentration factor is the larger, the smaller the root radius, its variation being extremely steep for the values of ρ/b less than 0.3. The included angle has a little influence in the region between 0° and 90°, and as it exceeds 90°, the stress concentration factor diminishes gradually. The depth of notch has such an effect as to give the stress concentration factor its maximum value when the value of t/b is nearly 0.15 to 0.25.

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We have studied on the following items : 1. The detection range of strain figures. 2. The relations between Luders' line and strain figures. 3. The equivalency of strain figures between a strain caused by mechanical stress and that caused by thermal stress. As a result of our researches, we have reached the following conclusions : 1. The yielding of steel or Fe-C alloy is due to the failure by slip of one phase of the two phases, such as ferrite and pearlite or pearlite and cementite. In an appropriate structure, we can detect the strain figures of steels from 0.05% to 3% in its carbon-content and some special steels. The strain energy of yielding disappears at the temperature of A₁ point. 2. Luders' line corresponds in position to a strain figure at a low temperature ; in other words, a strain figure appears at the same place that Luders' line runs ; but not at a high temperature, when it becomes a false figure. 3. The strain energy of mechanical stress is equivalent to that of thermal stress. Note : The details of their characteristics shall be illustrated by photographs.

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In order to clarify the mechanism of fatigue phenomenon, fatigue tests of mild steel and brass specimens under various constant amplitudes of repeated plastic strain and two other related tests were carried out. The following is the summary of these test results. (1) In the earlier stage of test strain hardening will progress, but subsequently the rate of stress increment will decrease gradually and the stress will saturate to a certain constant value, which corresponds to its strain amplitude. (2) The mutual relations among the saturated stresses, the strain amplitudes and the number of cycles up to fracture can be graphically represented by straight lines with respect to the log-log scale. (3) In the fatigue tests under two-steps-plastic-strain amplitude, strain softening can be observed when the amplitude of the second step is smaller than that of the first step. And it can be also observed that the first step always reduces the life in the second step.

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The problems of the fatigue of materials have been studied by many investigators, but there still remain many unknown factors, especially on the damaging effects due to the repeated stress with varying amplitude. In this study, we carried out the fatigue tests on the medium carbon steel by supperposing the higher stress reversals upon the fundamental repeated stress levels in order to discuss the process of fatigue stressing, and investigated the influence of the cycle ratio of the primary stress, the secondary higher stress level, and its reversals on the cumulative cycle ratio to failure. As a result, it has been found that the more the cycle ratio of the primary stress amplitude is and the lower the secondary stress level is, the greater the cumulative cycle ratio to failure becomes. Besides, we have interpreted these test results by the use of the cycle ratio-damage curves (D-R curves).

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For waterhammer analysis, the water level of reservoir has been hitherto generally assumed to be constant. But, in the case of surge tank, the water level as a rule fluctuates so widely that it is indispensable to investigate its effects. If the reservoir water level is expressed as H=H_L (t), that is, a function of time, the waterhammer equation can be derived as follows : H_i-H₀=a/g (V₀-V_i)-2Σ^^(i-1)__(i=1)(H_i-H₀)+2Σ^^i__(i=1){(H_L)_i-(1/2)-H₀} Applying this equation instead of the usual one, and using equations concerning surge tank together, waterhammer in pumping plant with surge tank is computed in consideration of level fluctuation. In practice, however, the conventional method, by which the flow and pressure transition is first calculated under the assumption that surge tank level remains constant, then level fluctuation is computed under the flow condition that is obtained above, and the pressure is modified, will give satisfactory results.

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Two methods to delay the separation of flow in short conical diffusers are described. The 10° conical diffusers, having a suddenly enlarged outlet, have great advantages over the simple conical diffusers of same length, when the equivalent angle of divergence is greater than 20°. When the interior wall near the separation point is roughened, the loss of flow becomes lower than in the case of smooth wall because of delay of separation point. A method of analysing the effects of the separation positions and boundary layer thicknesses, on the loss of flow, is described.

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Die Verfasser haben den Versuch uber den Druckverlust in der waagerechten pneumatischen Forderleitung durchgefuhrt. Um den zusatzlichen Druckverlust klar zu machen, wurde die Annahme gemacht, daβ der gesamte Druckverlust in der pneumatischen Forderleitung aus dem Druckverlust bie Stromung von reiner Luft, der durch die Blasiussche Formel λ=0.316 4/R^1/4₀ angegeben wird, und dem durch die geforderten Materialien verursachten Druckverlust bestehe. Fur den zusatzlichen Druckverlust ist die neue Formel λ₅=8/(√(8/λ)-1.72μ)² aus den Versuchsergebnissen abgeleitet worden, wodurch der zusatzliche Druckverlust unabhangig von der Gutsorte berechnet wird. Zur Ableitung der Formel werden nicht nur das Mischungsverhaltnis, sondern auch die Schubspannungsgeschwindigkeit berucksichtigt.

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The authors have made the experimental and the theoretical investigation of the screw conveyor. The theoretical values of the power and the efficiencies are in good agreement with the experimental ones, because the shape of the screw and the behavior of materials have been assumed to be close to the real phenomena to make the calculations easier. The experiments have revealed that : (1) There is an optimum ratio of pitch to outer diameter of the screw, (2) the tip clearance must be reduced as much as possible and (3) the total efficiency dicreases steeply, when the discharge of materials increases beyond a proper value for each screw. One of the conclusions (3) above has been theoretically analyzed, and a method to select the optimum dimensions of the screw and the profitable operating conditions of the conveyor has been explained.

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Recently there has been a heavy increase in the demand for volute pumps handing viscous fluids for chemical industries. It is suggested that the properties of viscous fluid influence the hydraulic performance of a centrifugal pump as compared with action of water, and already a few scholars have reported on this influence. It seems, however, that there remain many problems unsettled as to the pumping behavior of a volute pump handling viscous fluids. The authors measured the hydraulic performance characteristics of a 75 mm volute pump under various pumping conditions in order to analyze their characteristics. In this paper they describe the method of representing all the properties under various conditions and show the performance characteristic diagrams indicating the influence of viscosity.

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A method to measure the velocity distribution in a centrifugal pump impeller is developed by using two types of stream line photographs ; one is the photograph of the stream line relative to the impeller vanes, and the other is that of the absolute stream line. With the same method, the flow velocities of the bubbles of cavitation which appear in the flow through the impeller are also measured. The results of those measurements have shown that the velocities of bubbles are much larger than those of the water at the same discharge. Thus the cavitating flow of water is assumed to be a kind of compressible fluid mixed with vapour bubbles. By solving the equation of motion of this assumed compressible fluid, the velocity distributions of the bubble flows which are measured in this experiment, and at the same time, the mechanism of cavitation shocks, are explained.

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A similarity law is proposed and verified using a pump operating at several speeds. The work on the liquid by the rotor and the work on the gas by the liquid are theoretically calculated work with the ideal work reveals some of the causes to energy dissipation which characterize the pump. At a low speed and at a high compression ratio, the pump does not operate properly. The mechanism of abnormal operation is explained and the critical condition is measured for pumps with three different types of discharge ports.

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The author published earlier the study on surge-prevention of blowers with the method of "Surge-Preventing Valve Operation". In this report there are shown various types of operation to prevent surge by operating the surge-preventing valve with oil hydraulic controller which is of Askania type and are given the data which are necessary for designing of preventing equipments. There are also shown experiments on stability and adultation where an automatic surgepreventing unit is installed on the blower made for testing. The author tests how it influences upon hunting and adultation of the control unit to damp the flow in the lead pipes to the controller and to the meter. In the case of the damped flow to the controller the stability of the unit increases while adultation decreases. Throttling of the valve in order to eliminate hunting influences little upon adultation.

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A resonant surge of small fan duct systems has been investigated to clarify the fundamental natures of the oscillating phenomenon of this kind. The first report gives the details of our experimental apparatus and also of the results obtained. The values of frequency of oscillation measured have been used to analyse our systems to provide the equivalent lumped models for use in the theoretical analysis of the surge described in the following second report.

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The oscillation cycles of the fan duct systems with nonlinear forcing have been determined by phase plane integrations utilizing the equivalent lumped models obtained in the first report. It has been assumed that the instantaneous characteristics of the fan is the same as its static ones. Experimental and theoretical results have been found to agree well with each other. Although the fan duct systems chosen were simple ones and the fan pressure rise was only a few inches of water, it seems likely that the fundamental natures of surge have been clarified.

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We have obtained the heat transmitting tubes of a new type which are superior in point of heat transmission in the case of fluid flowing in them. We have studied experimentally the characteristics of our tubes, and already reported the results. We researched the heat transmission characteristics of the bundles of circular tubes having one, two or three rows of our new 1st tubes ahead. And we researched the characteristics of the ordinary tubes having transverse circular fins on their outer surface. The main results of our researches are as follows : (1) The combination bundle of 1st tubes as the Ist and IInd rows and simple circular tubes as the other rows has the heat transmission ability of more than 95%, and the pressure loss of 85%, comparing with the bundle of 1st tubes only. (2) The 1st tube has the same heat transmission ability as the ordinary ribbed tube, which has the fin area about three times as large as the one of 1st tube.

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In this paper, we carried out both the calculations of the thermodynamic properties and the drawings of the i-s diagrams for combustion gases composed of acetylene-air mixture, because acetylene has a few interesting properties compared with liquid fuels which are generally used for a spark ignition engine. Further, we performed the comparison with isochoric and isobaric heats of combustion found from each i-s diagram of acetylene and octane, it is indicated therefrom that the heat of combustion has a considerable difference between combustion gases of acetylene-air mixture and those of octane-air mixture under the state of higher temperature, larger specific volume, and lower pressure. For the above reason, this work may be useful in the case of a cycle calculation where the accuracy is especially required. The diagrams cover the following ranges ; excess air factors : 0.8, 0.9, and 1.0, temperature : 600∼3000°K, pressure : 0.1∼200 ata, and specific volume : 0.04∼60m³/kg.

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Air motion as well as mixture formation and flame pattern in the pre-combustion chamber of a Diesel engine was investigated by means of high-speed photography through a glass window on an engine in operation. By comparing the photographic evidences with the results of test performed under a similar condition, the following conceptions as to the improvement on the combustion were obtained : The main bulk of fuel should be transferred into the cylinder with the first blast of gas so that combustion in the pre-combustion chamber may take place under lean mixture. This state can be realized by keeping the fuel spray from being wafted back by an incoming air-stream and by concentrating a rich mixture near the throat of the chamber. Further, the mixture formation in the chamber is affected to a great extent by an air-stream, which flows in through the small passage during the compression stroke and then generally creates an air-swirl in the main part of the chamber. An excessively vigorous swirl sometimes results in preventing the earlier outflow of fuel, which brings about much soot formation.

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Using a high-speed motion picture camera, the authors made flame photographs through a glass window set on the cylinder head of a pre-combustion type Diesel engine. For the cases of various directions of gas outflow and also for various shapes of cavity on a piston crown, the process of mixing and combustion of the gas mixture blown out from the precombustion chamber, swirl creation and flame distribution in the cylinder were investigated. In addition, the suitable design of the main combustion chamber for improvement on the combustion was discussed by comparing the results of performance test obtained in a single cylinder engine.

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High-speed motion picture taken through a glass window in a full-scale engine, has led to the following information as to the combustion process in a Lanova Diesel engine. The fuel supply into the cell, which depends principally on the fuel injection and the design of the air-cell, has a large influence on the engine performance. The fuel spray, if injected through the injector with a small spray angle toward the mouth of the cell, does not produce much mixture in the main combustion chamber before ignition, which burns slowly until the outflow of hot gases from the cell has improved the mixture formation to such a degree that quicker combustion becomes possible. These processes contribute toward a slow pressure rise in the early stage of combustion and high thermal efficiency. Furthermore, it was ascertained by the high-speed photography that ignition in the main chamber starts generally before that in the cell, and at the latest simultaneously with the ignition in the cell.

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This paper deals with the influence of the exhaust pipe length upon the performance characteristics of a two-cycle Diesel engine. The two-cycle uniflow scavenged three-cylinder Diesel engine was employed, and the length of each exhaust pipe was changed from 20 cm to 420 cm. The following results were obtained. (1) The optimum performance was obtained at the following pulsation coefficients q, i. e. q=0.24, 0.70 and 1.16, q being defined as q=nL/15c, where n : crankshaft revolutions per minute, L : length of the exhaust pipe and c : sonic velocity in the exhaust pipe. (2) Theoretical treatment performed by one of the present authors showed fair coincidence with the experimental results. (3) The difference of output developed by the engine at good tuning and that at poor tuning was about 15%. (4) In the practical application of the present results especially to the variable speed engines, a shorter optimum exhaust pipe length is preferable to the longer one.

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The kinetic behavior of a mono-tube-boiler is very important for its control. Since the controlled variables of a boiler (pressure, temperature) are the complicated functions of enthalpy and distributed along the tube length, the kinetic analysis is not easy. In this paper, the author analyses it, supposing that the temperature is distributed but the pressure is lumped in the tube. The results are illustrated by a numerical example which represents the transient response for the stepwise change of fuel, feed-water and steam demand. He also applies them to the evaluation of the automatic control systems for mono-tube-boiler.

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The investigations of the basic cutting mechanism in the finishing processes using grains for the cutting edge are the fundamental measures for improving the finishing efficiency and for elevating the smoothness of a finished surface. The model cutting tests of grains have been carried out under such conditions that the cutting edge angle and the cutting speed may reproduce the original form of the cutting states of the finishing operations such as grinding, superfinishing and single-point cutting. As the result of these tests, the relations between the stock removal or the swell-up and the cutting edge angle or the cutting speed are clarified, and the influence of cutting conditions on the ratio of the tangential and the normal cutting force is found. Moreover, the relation between the cutting mechanism and the cutting speed is obtained.

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Chip, produced by steel cutting, has two kinds of plastic deformation : the primary deformation occurs in the flow region and the secondary deformation occurs owing to the friction between the chip and the face of tool. To find the effects of cutting conditions on these deformations, orthogonal cutting tests of carbon steel were performed. We observed the cutting ratio, the direction of structure flow, the roughness of chip surface, etc. under various cutting conditions (rake angle of tool, depth of cut, cutting velocity). Furthermore, we proved the reasonableness of existence of a flow region instead of a single shear plane assumed in the conventional cutting theory, by the difference between the measured and the theoretical angles of the inclination of chip flow.

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This paper describes the adhesion of cutting tools at high temperatures from the results of empirical cutting data and fundamental test on the adhesion between cutting tool tips and work materials. The adhesive tests were run in vacuum except where noted by means of the Vickers hot hardness testing machine. In consequence, we found that the critical temperature for adhesion was affected by the chemical composition of ceramics and kinds of metals and that the strength of the interface between ceramic tips and metals was weaker than in the case of carbides and this fact was recognized as one of the reasons why the crater wear and built up edge in ceramics were less than in carbides.

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In this report, the tests on growth of cast iron were carried out, and then properties of the grown-up cast irons as oilless bearing material for friction and wear were investigated. The following conclusions were reached. (1) The growth of cast iron ceased after the heating and cooling were repeated about sixty times. The amount of oil with which the grown-up cast iron was saturated was affected very much by the viscosity of oil and slightly by the kinds of oil at high temperature. (2) When the grown-up cast iron was saturated with the high viscosity oil, the temperatures of contact surfaces became finally constant even under heavy loads. (3) Even when the lubricant was not supplied, the wear was very small and was not affected so much by the number of treatments or kinds of saturating oil.

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The mechanism of straightening of sections and rails by means of a roller straightener with axial adjustable rolls has not been clarified. The auther studied this problem analytically and derived the relations between the largest radii of bending necessary for straightening, at the points of the second and third rolls of straightener and the results of straightening, when the modulus of elasticity and curvature of sections before operating are known. The auther also shows, as a special case, that the sections can be straightened not only in horizontal plane, but also vertical plane in accordance with severe bending in even horizontal plane by the straightener rolls. The present paper deals with the repeated bending tests and the tension-compression tests for specimens of hard steel, mild steel and brass, as these characteristics of repeated cold works on these materials are the most important points for designing the straightening machine.

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As the power shovel must deal with the earth in its work, it receives severe impact loads which vary according to the digging conditions and operating method. These impact loads are very difficult to grasp theoretically and there have been only a few theses ever written on this subject. This report deals with analysis of oscillogram recordings taken on various factors concerning power shovels in actual work. The points clarified by this study were as follows. (1) Degree of impact torque applied on the power shovel during digging, swing and travelling. (2) Reduction of impact and improvement of working properties by wing a fluid power transmission device. (3) Adaptability of secondary impedance system motor for the shovel work of an electric power shovel.

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Ability of human being as an operator of braking mechanisms was investigated. Effect of posture on foot and manual force, delay and transient in handling brake pedals or sticks, and experimental formulae for these were discussed. For service brakes, 20kg for passenger cars, 30 kg for commercial vehicles may be desirable. It will take less than 1.2 and 1.4 sec for 80% of males and females respectively from stimulus to full application. Posture of passengers and transient of application has prominent effect on riding comfort at braking. Using actuating mechanism developed for this test, fade phenomena during braking on the road and at the dynamometer were observed. Effect of lining characteristics, shoe type, and thermal condition of brake mechanism were calculated using analogue computors.

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