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Among the factors affecting the stiffness of paper, the effects of density, loading and basis weight were studied on the hand-made sheets. A formula and a diagram, by which the effect of basis weight on the stiffness can be calculated independently of pulp variety, beating equipment and pulp freeness, were derived and the concept of stiffness factor was defined as follows.log S =log a+1.832 log WStiffness factor=S(100/W)1.832where S=stiffnessW=basis weight in g/m2 α=α constantAlthough “Koshi”, one of the Japanese traditional methods evaluating paper quality is not a mere stiffness but it depends on the sense of human being, a formula evaluating “Koshi” was derived and it was named “Composed Stiffness”.Composed Stiffness= [S- (1.0-D)× 86.7]× D×T.S.where S= StiffnessD=Density in g/cm3 T.S = Tensile strength in kg

The hypothesis of oxidative and fatigue abrasion phenomena as the major cause of tire tread wear in normal operation has led to development of a laboratory test machine for which low severity, obtained by using paper tape as abrading material, and full temperature control are outstanding characteristics. Good uniformity and reproducibility of abrasion are obtained if proper care is taken. Proof of the basic theory and of its applicability to such a machine has been obtained through a survey of the effects of antioxidants in compounds and of test temperature variation. Application of this test method to tire tread compounds has given fair results here it has been possible to establish testing conditions sufficiently related to those in road tests. When these latter include a large range of severities, comparisons are less favorable and further study is being made to try to accommodate such cases.

Mechanical behavior of the paper for power cable under dry condition was studied. The samples w ere impregnated with insulating-oil or microcrystaline wax after drying, and tensile strength, elongation, folding endurance, bursting strength and tear resistance were measured.(1) Comparing the mechanical strength under dry condition with that RH 65 %, there was remarkable change in the elongation of C. D (cross direction) and the folding endurance of both directions, C. D and the M. D (machine direction). Especially, the folding endurance of M. D showed the decreases of about 98%.(2) The order of properties which had been effected by heating was as follows;folding endurance>bursting strength>tear strength>elongation>tensile strength.(3) Comparing the heating in the air with that in the vacuum, so much difference was not approved by heating of 110°C and 130°C in all the properties, but remarkable change was recognized at 150°C.(4) Some difference was shown on the extreme decrease both direction, M. D and C. D by heating and remarkable difference was shown in the folding endurance and elongation by heating in the air.

This paper describes the design, manufacture and tests on a 500/550 kV cable and joint. The cable successfully withstood 1550 kV impulse and 1290 kV switching surge established by Electric Research Council for the Waltz Mill field tests. The 60 Hz tests demonstrated the cable with either a splice, insulated to 2 times the insulation O.D. or 1.5 times the insulation O.D. had adequate ac dielectric strength.

ロ紙を水平空間に保持するopen-strip typeと,著者が自製したガラス板で口紙をはさみ密閉,冷却できるようにしたsandwich typeの2種類のロ紙固定方式にて,ロ紙上物質の移動と泳動電流によるロ紙の発熱,それに伴って生じる電解液の蒸発,ロ紙の毛細管浸透現象による電解液のロ紙中央部に向う流れとの関連について調べた.open-strip typeはロ紙の発熱が著しく,このため泳動方向,泳動像,泳動速度などに安定した結果を得ることが困難であり,また泳動電圧を高くすることは不可能に近い.これに対してsandwich typeではこれらの影響を受けにくく,再現性もえやすいうえに高電圧を加えることが可能であった.それでこのsandwich typeを用いて100V/cm程度の電位こう配にて泳動を実施できるロ紙固定台を試作し,泳動結果の再現性を簡単なグラフにて表現することを試みた.

A Stiffnesstester of paper, the principle of which is based on the measuring of the bending monent of a piece of Sheet-paper by the aid of a pendulum, the moment of which was, previously, calculated, has been devised by authors.The measuring conditions by this tester were settled and the errors caused on measuring it were discussed.From the data of stiffness obtained, the static Young's modulus were calculated and compared with the dynamic Young's modulus obtained by the vibration method, which consists of giving vibration to a piece of sheetpaper.The static Young's modulus do not almost coincide with the dynamic Young's modulus ; and as a general tendency, the former is smaller than the latter and the softer the paper is, the larger the difference becomes.Such a difference will be, on the one hand, caused by the defect of the stiffnesstester, and on the other hand, by the visco-elastic structure of paper itself.But as a routine work, this stiffnesstester will be able to provide a numerical data of stiffness of paper, which are provably affected by the paper making conditions : such as freeness of fibre, type of beating of stock, additives, sorts of pulps, bonded area of fibre etc ; and the relationships among them were investigated on the data obtained by this test. As a factor affecting to the stiffness, the bonded area of fiber has been recognized to be prominent.From the above experiments, it will be considered that there is a closs relation between the stiffness and the micro-structure of paper. To investigate the stiffness of paper will, therefore, be able to contribute toward the study on the micro-structure of paper.

The testing machine for the strength of paper under impulsive force was constructed, and its usefulness for the test of bag-paper was assured. It indicates the rupture energy of paper impact conditions, which is consumed by specimen before rupture.The impact strength testing machine is shown in Fig. 1. In fig. 3 fig. 5, the results of the falling test are compared with the tensile strengths, impact breaking strengths measured by using a rochelsalt combined with an oseillograph, and rupture energies.It is shown clearly that the rupture energy represents in best the strength of paper-bag. The rupture energy is not linearly proportional to the length of specimen, and this may be caused by the propagation of shock wave through paper.

FOR a number of years the standard low-tension direct-current feeder cable in Chicago was 1,000,-000-cir. mil two-conductor concentric paper-insulated cable with three pressure wires laid up with the outer conductor. Apparently there has been the greatest tendency to overload this particular size of cable more than any other as, with both single and concentric cables in service, it was difficult to make a proper distinction between the carrying capacity of the two kinds of cables. About ten years ago we had two cases in which the cables of this kind were called upon to carry loads somewhat larger than had been customary, and steadily throughout the day instead of a short peak in the evening. The two customers in these cases, in different portions of the city, were both manufacturing customers with an eight-hour load, and on account of some increase in business they increased their load on short notice when no cable was available for another feeder to their premises. In each case, the cable has to be ordered from the factory so that this unusual load was carried by these cables for some three or four months. In the first case of this kind we were so disturbed about the temperature that we made a rather extended series of temperature measurements, using one of the pressure wires imbedded in the outer conductor as a resistance, and determining the temperature by the rise in resistance. This, of course, would give us the temperature of the outer conductor which would be probably 8 or 10 deg. lower than the inner conductor. The temperature measured in this manner was slightly above 100 deg. cent., and as there was some doubt regarding the accuracy of the determination made in this manner, it was checked by cutting a small hole in the lead sheath of the cable and in the outer insulation, and measuring the temperature of the outer copper with a thermometer. The temperature taken in this way checked very closely with the temperature as determined by the rise in resistance of one of the pressure wires. The insulation removed in this manner was carefully preserved and compared with the insulation in a piece of new cable, and it was impossible, by careful examination, to discover any appreciable difference.

The analysis of externally pressurized, plane, oil-film pads has been mainly restricted, in the current literature, to simple pad shapes without tilt or relative sliding action or squeeze effects. As tilt can arise owing to manufacturing tolerances, or by dynamic inertial forces causing elastic deformation, it is important to assess the combined effects of tilt and sliding action in order to predict such factors as the stability of the system or the onset of cavitation. This paper presents general numerical solutions from the Atlas digital computer of the Reynolds equation applied mainly to circular pressurized pads. Results for a square pad and for an infinitely wide pad are also given. The load and location of the centre of pressure, the impedance of the pad and thus the flow rate are calculated in dimensionless form for any combination of tilt, sliding velocity, and squeeze rate. It is argued that these calculated terms are required before any dynamical problem, involving loaded hydrostatic bearings, can be attempted and before refinements of film lubrication theory can be incorporated. This paper illustrates the application of the results to dynamical problems.

This paper contains the results, plotted non-dimensionally, of extensive tests carried out on a 1–625-in diameter grinding machine spindle lubricated hydrostatically. The horizontal spindle is directly coupled to a variable-speed motor at one end and loaded vertically at the other. The spindle is not constrained to rotate at arbitrary eccentricity values, but is able to seek an equilibrium position depending upon oil flow and rotational speed. The attitude, oil film thickness, and eccentricity are measured by mutually, perpendicular capacitance probes arranged in the bearing housing. The results indicate considerably decreasing load-carrying capacity as the rotational speed increases, because the hydrodynamic effect tends to centralize the shaft in the bearing housing, thus nullifying the hydrostatic effect. Paradoxically the same effect causes an increase in oil film stiffness as it is generally defined. A summary of earlier work is included, notably that of Raimondi and Boyd who considered bearings of fixed eccentricity, and the paper also presents a theoretical analysis based on the pressure- and velocity-induced circumferential flow theories.

Synopsis The Paper presents a general plastic theory for the solution of statically indeterminate reinforced-concrete frameworks, and also for calculating the ultimate strength in bending of reinforced-concrete and pre-stressed-concrete beams, of both bonded and non-bonded types. The Author has attempted to avoid the use of complex mathematical methods by assuming that all bending strains have linear distribution. The neutral axis of members subject to bending is located by the ultimate strains at the extremities of the section for non-sustained load, and safe limiting values are determined by tests. The shape of the compression-stress distribution and the position of its centre of gravity are denoted by symbols for which safe limiting values are obtained experimentally. A plastic theory for the ultimate longitudinal bending strength of cylindrical shells is also presented. The Author indicates the distribution of longitudinal stress which causes maximum transverse bending stress so that, again, simplification is achieved by the use of safe limiting values which may be based on experimental evidence. Tests to destruction on pre-stressed beams and two cylindrical shells, and the methods employed for measuring strains by dial and electrical gauges, are described and also the procedure for determining, from the tests, safe limiting values of the factors which govern ultimate strength. The experimental work is not yet complete, but some of the results so far obtained are given. Final results will be given in an Addendum to the Paper. A new method of testing is described, in which a machine referred to as a bending-simulation machine, is used to obtain the fundamental stress-strain data required for calculations within the plastic range.

During the past five or six years, practically all of the American cable manufacturers have made some changes in their impregnating compound so as to produce cable having a low dielectric loss. In a number of cases, these compounds were not well chosen. During the same period, some of the operating companies have reduced the thickness of their insulation, resulting in increased dielectric stresses. In a number of cases, the compounds and perhaps also the paper that was used developed faults that were more serious than high dielectric loss. Some cables have been very deficient in dielectric strength and others have developed a new type of trouble which has been termed ``ionization'' and, after a comparatively short time, the operating voltage of such cable had to be materially reduced in order to keep the lines in service or the cable had to be replaced. The cable manufactured during this period has generally passed, with a wide margin, the high voltage tests required by the specification. Occasionally a lot of cable which passes these tests by a narrow margin will be shipped by a manufacturer and, in such cases, the service record of the cable is unsatisfactory. The investigations which form the basis of this paper consist of: (a) Laboratory tests to determine what high-voltage tests cable known to be of good quality will withstand as well as the similar tests on other grades of cable.

The paper deals with those tests which are involved in specifications. The discussion is from the standpoint of the purpose and significance of the various standard tests which are made rather than that of the technique of the details of testing. A considerable number of data are given. The subjects treated are purpose and importance of tests of cable; insulation resistance test; high-voltage test; dielectric loss and power-factor test; ``ionization'' test; bending test; accelerated life test; preparation of samples for high-voltage tests and tests of components. The possible significance of wide variation in some of the properties of cable is discussed. The relation found between time and voltage based on a large number of tests of both three-conductor and single-conductor cable is discussed at considerable length. A test for stability of the impregnating compound is described as is also a proposed standard load for dielectric-loss testing. Some data are given showing the effect of repeated bending on lead and how that effect is influenced by the tensile stress in the lead. The paper concludes with a list of the ways by which, in the author's opinion, progress can be made in the improvement of the quality and the design of paper-insulated high-tension cable.

In my former paper on this subject, I pointed out the existence of an element of strength in beams when subjected to transverse strain, which had been omitted in the generally admitted theory. The forms of beam employed in the experiments described in that paper were only of two kinds, namely, solid rectangular bars, and open beams or girders.

The objects of this paper are to demonstrate the use of the method described in Paper 6 and to give an indication of the effect of design parameters on the performance of a dynamically loaded bearing. An investigation into the main and big-end bearings of a diesel engine of modern design is described. The performance of a bearing is gauged by obtaining: (a) the minimum oil film thickness, (6) the maximum pressure developed within the oil, (c) the maximum load/projected area, and ( d) the bulk oil temperature rise. The influence of the engine design upon the big-end bearing performance for the particular engine under consideration is found by investigating the effects of the following parameters: ( a) bearing length-diameter ratio, (6) removal of centre-circumferential groove, ( c) inlet temperature, ( d) bearing clearance, and ( e) loading diagram. This last parameter is varied by changing in turn the piston mass, the connecting-rod mass, and the position of the connecting-rod centre of gravity. Finally, the effect upon the main bearing performance of various balance weight configurations is demonstrated. The usual assumption is made to obtain the main bearing loads: that loads imposed by a crank throw are equally distributed between neighbouring main bearings. General conclusions are made regarding the relative influence of certain bearing-design parameters upon the bearing performance.

These experiments are a continuation of those described in my papers read February 26th, 1866 and February 7th, 1867. They were made during the Winter Session of 1866—67, in the same place, and with the same apparatus as the later experiments on the steel rod (see p. 150 of last paper), the observer being Mr. Zaccheus Walker, student of Engineering, who has been already mentioned as joint observer in the experiments on the steel rod. I personally inspected the apparatus from time to time, and assisted in the taking of those measurements which only required to be made once for all in the case of each rod. The weights, in air and water, of the portions of rods operated on, were observed by Mr. John Tatlock, Laboratory Assistant to Sir William Thomson, who also performed this portion of the labour in the previous experiments. The rods operated on in the experiments now to be described were three in number, and were of malleable iron, cast iron, and copper respectively, those previously operated on being of flint glass (two specimens), brass, and steel.

LACK of factual information relative to the permissible pulling loads to which solid-type impregnated-paper lead-sheath power cable might be subjected by means of woven-wire pulling grips without damage to the sheath prompted the Insulated Power Cable Engineers Association to consider the subject and resulted in the laboratory tests described in this paper.

In order to find out the relation between the stress and strength of light-weight simili paper, which is apt to be broken by the impact on the automatic candy packing machine, an impact tester has been devised by us. As the test pieces three types of light-weight simili paper having different beating degrees were used. And at the same time by way of comparison, glassine paper and cellophane were examined, as it is known that the former is made of slow stock and the latter is poor in tearing strength but shows high value in elongation property.These test pieces of simili paper were suspended in U-forr, and twelve types of dropping impact which are likely to happen on the candy packing machine were given to them. In the course of the impact tests, a roll-type weight suspended horizontally was dropped so many times onto the test pieces. After repeated tests conducted in this manner, the drop distance of the weight high enough to break them and the places on the test pieces that were broken were determined to a certain extent.It was observed from the results that the farther the centre of gravity of the weight dropped is away from the centre of the test pieces and the larger becomes the angle of the centre line of the weight against them, the less impact is enough to break them. Furthermore, the strength of the paper which has the closest relation to the impact was roughly determined by this test.

This paper describes two different computer programs for the calculation of rolling bearing applications in an automotive driveline. The first program gives the effect of bearing preload or internal clearance on bearing deflections and nominal lives in bearing applications with taper roller bearings. As an example, the paper deals with a front hub bearing arrangement with two taper roller bearings used in a front wheel driven car, and also with a pinion of a final drive unit and a gearbox mainshaft incorporating two taper and one cylindrical roller bearing. The second program is used to determine the influence of misalignment and shaft deflection on the load and life of a deep groove ball bearing. To illustrate this effect the layshaft of an automotive gearbox is studied.

The three experimental processes and results are described on this paper by using the paper impact strength tester.The first is an appendix report of regular impact strength test which has been described in 1954.At the second report, the four creasing style sample of paper were measured by impact strength tester.There were good correlation between drop number of bags and impact strength about creasing parts of bags.The third report is on the mechanical properties of paper during the repeated impact loading.The very interesting results were obtained about the repeated impact strength and various moisture content of paper

The design of a rig to determine the load and attitude relationships of a hydrodynamically lubricated bearing under steady and dynamic loading is described. The bearing is nominally of 3 in diameter with a diametral clearance of 0·0075 in. Two bearing lands of length-diameter ratio of 0·282 are fed by a central circumferential oil groove. It has been designed on these model conditions to minimize bearing distortion and temperature gradients in order to provide a basis for comparison with the results of the computer program reported in Paper 6. Two perpendicular load components are applied mechanically through spring levers displaced by cams. The load components are measured by strain gauges and the displacement of the bearing is detected by four inductive pick-ups. The arrangement of these permits the relative linear and angular displacements of the journal and bearing axes to be determined. Inlet and outlet oil temperatures are measured for viscosity determination. Both steady and dynamic loads are applied by the loading system. Load diagrams of approximately circular and elliptical form may be obtained directly by adjusting the magnitude and phase of the eccentrics serving as cams, while more complex load patterns may be obtained by special cams. The polar load diagrams recorded are used as data for the computer program of Paper 6. Theoretical and practical results are then compared.

The structural properties of paper as low-cost building material are investigated in a pilot study which gives the results of a limited number of tension, creep, and flexure tests. Certain problems encountered in all-paper construction are discussed, the significance of creep is considered, and a mode of failure peculiar to all-paper construction is observed. The structural integrity and flexibility of form available with paper are illustrated by the fabrication and testing of a cylindrical shell.

At partial and overload conditions, radial decentralizing forces act upon the rotor of a centrifugal pump with guide vanes if the impeller is out of centre. The magnitude of these forces depends on load conditions, and the forces increase with growing eccentricity. At very small flow, these forces become non-stationary. They rotate at a considerably lower frequency than the velocity frequency and may lead to rotor vibrations. The paper discusses the effects of stationary and non-stationary radial forces, and resulting shaft deflections and vibrations, from measurements on two experimental test rigs. The paper also presents the results of research on the pressure distribution of guide vanes, carried out in air, and gives observations of flow patterns in a shallow water test rig.

The test required for the improvement of JIS P 8132 was carried out. The result was as follows.1) No significant difference of the elongation was observed between testing with the initial load or (initial strain) and without it. The initial load, therefore, could not be given to the specimen in testing the elongation of paper and paperboard, if the specimen is set on the clamp of the apparatus carefully.2) The method of correction was investigated considering the mechanism of measuring the elongation with the constant rate of elongation apparatus. The correction is performed by looking over the strain of the loadcell and chuck under testing the standard specimen of metal with this apparatus.

The paper describes a practical method of calculating the aerodynamic effects of trains passing through interconnected tunnel systems so that these can be designed for acceptable pressure pulse levels, air velocities and train drag. The equations of unsteady compressible flow were developed into a form suitable for solving by the Method of Characteristics on a computer. Results obtained were compared with measurements taken on models and in real tunnels and some of the comparisons are shown and discussed.

This paper deals with ball and cylindrical roller bearings in drivelines where, year by year, requirements demand that smaller bearings meet conditions of steadily increasing severity. Clutch-operating bearings and those for manual gearboxes and overdrives are reviewed. The different requirements for bearings in front-wheel drives and automatic gearboxes are discussed, followed by a consideration of the requirements of propeller shafts, half-shafts and hubs.

Thin cylindrical shells subjected to high bending loads normally buckle by forming a number of diamond- shaped panels on part of their compressed surfaces. The values of the buckling loads show considerable scatter but are in general substantially less than those predicted by simple linear theory. This paper describes an attempt made a few years ago to improve the buckling strength and to reduce the scatter in the buckling loads of such shells by means of internal pressure. It was expected and confirmed that internal pressure would increase the buckling loads, but little improvement was obtained in the amount of scatter. Considerable modifications of the buckling deformations were observed; at sufficiently high pressures the diamond pattern disappeared entirely and was replaced by a single ridge of deformation extending circumferentially around the compressed side of the shell. An account is given of the experimental investigation together with some excerpts from the theoretical work. Most of the shells were formed from thin steel sheets bent into the shape of a cylinder then soldered down a generator. They were filled with water, plugged at their ends and put under pressure by means of a hand-pump. Observations made during bending included load, pressure, strain, deflections and mode of buckling. These are discussed and compared with the results of other investigations.

In support of the vast amount of stress analysis work on components, considerable effort is required to provide suitable materials behaviour models. Simple laboratory tests on uniaxially loaded specimens under constant temperature condition provide the bulk of data, but methods are required to translate these data to multiaxial conditions with non-uniform cyclic loading and cyclic temperature. The material behaviour laws, therefore, are aimed at meeting two requirements: first, to predict the deformamation response in terms of the imposed loading conditions and the previous history of the material; and second, to analyse the stress or strain cycles to predict failure. This paper reviews the steps being taken at Berkeley Nuclear Laboratories, C.E.G.B., and elsewhere to achieve these two objectives.

Measurements have been made of the rate of fire spread in a solid fuel array consisting of horizontal paper strips standing on edge, separated by various amounts of space. It is found that ignition transients show evidence of several burning modes and in some cases the steady burning can also occur in two different ways, at different speeds. The steady spread rate correlates with the height spacing ratio for both low and high values, but not for intermediate values. The available fire-spread theories are shown to be self consistent in the sense that the predicted relationship between various measured quantities is verified. However, the absence of the possibility of prediction of burning-zone properties, prevents the prediction of fire-spread rate from first principles.

The dynamics of existing railway vehicles on straight track is dominated by motions in the lateral plane commonly referred to as hunting. Hunting is a self-excited oscillation caused by the combined action of the conicity of the wheels and the creep forces acting in the contact plane between wheel and rail. In this paper existing and recently developed theories of the lateral motion of railway vehicles are discussed in relation to experimental work on both models and full-scale vehicles. It is shown that a realistic theory taking into account flexibility between the wheelsets and the frame in the longitudinal, lateral, and vertical directions, and the influence of wheel and rail profiles, yield values for the critical speeds which are consistent with experimental results. The influence of various parameters on stability is discussed and it is explained how railway vehicles can be designed for stable running at high speeds. Examples of suitable choices of suspension and other parameters will be given and experiments carried out in order to verify these concepts will be described.

This paper describes a theoretical and experimental study of the non-steady flow performance of a centrifugal compressor. The experimental work was designed to study the effect of pulse frequency on the compressor performance, for a given delivery configuration, using a rotary valve pulse generator. The experimental rig was designed so that it was possible to study the reverse flow and the pressure pulsations in the suction side of the compressor. The objective of the investigation was to discover how the compressor performance deteriorated with pulse frequency, and also to determine the frequency at which reverse flow through the compressor first occurred. The objective of the theoretical work was to predict the onset of reverse flow through the compressor and the mean and transient delivery pressure ratio using the conventional stationary pipe non-steady solutions by the method of characteristics. The compressor unit was replaced by a boundary condition within the pipe system equal to the experimentally known steady flow characteristics of the compressor. The physical size of the compressor was replaced by an equivalent pipe length; this technique is described. The theoretical results are compared with an extensive series of experimental results. This work is a direct extension of that given in reference (3).

The experimental work reported in this paper has shown that it is possible to proceed into and beyond the half-speed whirl region and operate at much higher speeds without vibration, using plain cylindrical journal bearings. Journals of 1-in diameter, clearance ratios greater than 1 in 1000, and bushes with length-diameter ratio of 1 were used. The bushes were mounted flexibly in rubber O-rings.

This paper discusses the dynamic behaviour of two designs of railway vehicle, taking into account the non-linear features of their suspensions and of the forces arising between rail and wheel. The parameters required for the theoretical analyses are obtained from measurements of the vehicles and from detailed studies of rail and tyre profiles. The vehicle behaviour is then predicted and these predictions are checked against running tests made on a special test track. The main features discussed are the lateral motion on plain track (hunting) and the response to an isolated vertical irregularity (a ‘dipped’ rail-joint). The effect of various parameters on this behaviour is described and some comments are made upon the problems of derailment.

This paper is concerned with the machinery for the launching of aircraft from and the recovery of aircraft on to the flight decks of aircraft carriers. The machinery to do this is hydraulic—except for the working fluid of slotted cylinder catapults, which is steam—and is required to control the application of large amounts of energy, in a short period, precisely in accordance with a set programme, with complete consistency and absolute reliability. Hydraulic machinery has successfully met all these requirements for fifty years, being developed and revised to keep pace with the increases in the performance of carrier-borne aircraft. The major developments—catapults for launching and arresting gear for recovery—are described, together with some items of ancillary equipment that demonstrate the versatility of hydraulic machinery. Simple principles have always been used, but the designs have always made use of the most advanced techniques of hydraulic engineering.

In this paper, both Hooke's joint and the modern ball type constant velocity unit are considered. Methods by which the specific capacity and life endurance of a joint may be estimated are described. A method of calculation to select a suitable joint for automotive purposes is discussed.

The usual methods of testing alternating-current high-voltage paper-insulated cables are based upon the ability of the insulating material to withstand excessive potentials in order to determine its condition. Accordingly, these methods are not suitable for routine tests imposed for the purpose of determining the degree of deterioration existing in any particular cable. In an effort to develop a routine test, which will serve to detect an impending fault, use has been made of the kenotron as the source of high-potential direct-current. By means of it a large volume of data has been secured concerning the input-current, for a cable, as a function of time after complete electrification at a constant high potential. These data when plotted, as curves, show by their shape the condition of the cable insulation. Curves showing a sharp decrease in the magnitude of input-current during the first minute and a gradual but persistent rate of decay for the succeeding six or seven minutes indicate that the insulation is in an acceptable condition from the operating point of view. Curves showing little, if any, decrease or a persistent tendency to increase during the time interval of the test indicate that the insulation has deteriorated to such a point that the cable may be expected to fail at an early date if retained in service. The degree of deterioration is indicated first: by the time which has elapsed since complete electrification before the increase occurrs, and second: by the sharpness of the upward trend of the curve in any instance. The value of this method of testing has been demonstrated by its actually having detected a considerable number of impending cable faults before they became a menace in operation. Additional refinements in the methods of measuring the input-current for different classes of cables may be desirable. Further investigations are being carried on to determine this necessity. Investigations of certain theoretical features are also being carried on. These include, among other things, oscillographic studies of the input-current and voltage under test conditions.

Many lubricated machine contacts can be represented by cylindrical surfaces, and some of these contacts such as gears and rolling contact bearings have been studied extensively in recent years within the developing subject of elastohydrodynamic lubrication. When high loads are carried by the contact, side leakage is of little importance, but there is little evidence to indicate the quantitative importance of side leakage when the loads are light. This question has assumed greater importance with the recent recognition that many nominally parallel surface thrust bearings rely upon thermal distortion for their effective load-carrying capacity, since the deformed shape can be approximated by a pad of cylindrical form. In this paper solutions of the Reynolds equation are presented for the geometry of a cylinder near a plane lubricated by an isoviscous fluid. The resulting pressure distribution has been integrated to yield normal and tangential surface force components and the results are presented in the form of side-leakage factors to be used with the Martin solution for an infinite cylinder. The approximate ‘short-cylinder’ theory is presented and compared with the full computer solutions. The results are applied to two lubricated contact situations.

The analysis of the strength and stiffness of a diesel engine frame can be carried out in two parts; an analysis of the whole frame loaded by the inertia of the moving parts and an analysis of one line loaded by the explosion forces. This paper describes computer programs which have been used to make the above analyses in more detail and in less time than is possible by hand calculation. Results are given for an engine frame in which one program was used to determine the shear and bending forces on the frame and the loads on the ligaments between the various holes in the sides of the frame. Another program was used for the analysis under explosion forces; the walls were divided into a large number of elemental panels (each of side about 2 in) and the stress distribution (both direct and bending) in each of these elements was determined.

This paper describes investigations that were undertaken to identify the reasons for fatigue failures in cast iron and aluminium pistons of large diesel engines. The work involved experimental and theoretical stress analyses, and fatigue tests were made on specimens cut from actual pistons. It was found that four pistons which suffered fatigue failures had safety factors of 0·60, 0·68, 0·94, and 0·96, while three modified designs which performed satisfactorily were assessed to have safety factors of 1·1, 1·24, and 1·57. Special attention is drawn to the method of fatigue testing in which features typical of the piston are retained. While it is considered prudent to design for safety factors substantially in excess of unity, the results presented should promote confidence that this approach to the design of components is valid not only in this case but more generally.

Calculation procedures for the design of nitrided gear teeth commonly use a basic allowable stress which is constant for a particular core tonnage and case depth. The purpose of this paper is to determine the distribution of stresses in nitrided rolling elements, including gear teeth, and to illustrate the effects on the theoretical basic allowable stress of the size and geometry of the gears. Two criteria of fatigue failure are compared and the predicted values are compared with test results.

(1920). XIX. The buckling of deep beams. (Second paper.) The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 39, No. 230, pp. 194-223.

This report deals with an investigation of eddy-current losses in multi-core circular-conductor and shaped-conductor paper-insulated wire-armoured cables, and the development of formulae by means of which the losses can be computed. The experimental work covers tests with balanced three-phase currents at frequencies from 25 to 300 cycles per second. The eddy-current losses are divided into four parts, namely, skin effect, proximity effect, lead-sheath effect, and armouring effect. The ratio of a.c. to d.c. resistance of the conductors, calculated by the appropriate formula, is, with one exception, within 5% of the measured value under all the conditions covered by the investigation, the average difference between calculation and measurement being only 1%.

It is generally accepted that the performance of compensated externally pressurized journal bearings is superior to ordinary journal bearings. This paper presents the experimental results of performance studies of compensated and uncompensated journal bearings under static and alternating loading with an operating frequency of 327 c/min. The length/diameter ratio of the test bearings was 1/3 and both bearings had 10 closed-end grooves machined in the bearing surfaces. Film pressure surveys reveal considerable differences in the film pressure distribution in the two bearings, and explain the difference in the performance characteristics of these bearings. Comparisons are made in terms of measured load capacity, stiffness, and lubricant flow rates. The relative costs of manufacture and the operating costs of these bearings are also discussed.

This paper presents a theoretical and experimental assessment of the eight coefficients which describe the stiffness and damping properties of journal bearing oil films, together with their subsequent use in predicting the performance of a real rotor. The performance is checked experimentally.

The paper deals with large slow-speed marine engines with a section on crankshaft stresses, including dynamic torque calculation; static bending moments owing to firing pressure, inertia, and misalignment; combined torque and bending stress; and experimental determination of stress concentration factors in the fillet radii. Other sections deal with top end bearing loading including cyclic variation, piston head stresses, deflection of bearing housings, prestressing of main bolts, frame stiffness, and stress in combustion chamber studs as a result of pressure and thermal loading.

Dovetail pole root fixings, consolidated by tapered keys, are a feature of many large-diameter salient pole alternator rotors. This paper describes an investigation into the failure in service of such a fixing; the failure being ascribed to fretting fatigue and resulting from a combination of tensile centrifugal loadings and superimposed oscillatory loading. The failures were reproduced on a series of full-scale joint sections and the design of a special rig, capable of applying typical oscillatory forcing superimposed upon a steady tensile load of 100 tons, is described. The rig was used to assess quantitatively the effect of various measures taken to eliminate the cause of failure. The test specimens were hand fitted to normal manufacturing methods and, despite the inevitable variations in fit, failed in a consistent manner. The results of the tests provide a practical example of fretting fatigue, and are generally in line with the findings of a fundamental investigation using small specimens and published in 1967 by Field and Waters. The dramatic improvement resulting from relatively minor geometrical changes is clearly demonstrated.

To prevent or minimize the erosion of the last row rotor blades in large high-speed steam turbines it has been proposed to remove the film of water on the surfaces of the last row stator blades before it reaches the trailing edges and is swept off by the steam drag into the path of the rotor blades. The paper describes experiments with a cascade of hollow stator blades with various dispositions of slots providing communication from the blade surfaces to the hollow cavity. The same cascade was used in turn with three different wet air tunnels, the experiments thus covering a wide range of Mach number and Reynolds number. With suitably disposed slots, and bleeding a very small proportion of the working fluid, about 90 per cent of the deleterious water can be removed, thus preventing it from striking the moving blades.