bluuebunny/crossref_metadata_2025 huggingface dataset:
The Mechanics of Electrical Switchgear
Authors: Trencham H.
Published: October 2007

The importance of mechanics in the design of switchgear is emphasized, and attention is drawn to the desirability of applying to switchgear the best that mechanical science has to offer. The functions of switching apparatus are set out in detail and the forms usually taken by the devices for performing these functions, and their relationships to each other, are described.

The following are instanced as typical mechanical problems in switchgear design: the strength of complex enclosures against internal pressure; oil-tight joints with insulators; the use of Portland cement with insulators; mechanisms for operating circuit breakers, including internal linkages and external actuating devices; the design of contacts.

Essential and arbitrary variations in switchgear design are considered, the former including voltage, amperage, frequency, breaking capacity, and location; and the latter, evolution, economic pressure, safety requirements, and individual preference. The incidence of the causes of variation is indicated and some attempt is made to describe their range of action. A short summary is given of the effects of the wide variety in demand, and the expected course of future progress is indicated. Appendixes are given exemplifying the application of simple mechanical calculations to circuit breaker mechanisms, and the usual loadings on various forms of contacts are tabulated.
Gas Works Practice
Authors: Birks F. M.
Published: October 2007

Gas manufacture is generally carried out in either horizontal, continuous vertical, or intermittent vertical retorts supplemented by carburetted water-gas plant. At the present time a certain amount of gas from coke oven plants is purchased, but only one such installation is at present in use on a gas works primarily for the production of gas.

All four types of carbonizing plant, together with the carburetted water-gas plant, are described briefly, and a table is put forward to show the results obtainable from them. Four thermal balance diagrams demonstrate the possibility of heat recovery from the waste flue gases, hot coke, and the hot coal gas by the generation of steam. A brief description of the various ancillary plant employed is given, whilst the production and use of steam is discussed more fully. The use of back-pressure steam is advocated and a table shows the variation of power requirements in six works, two each of the three main types of carbonizing plant.

A brief description of the recently reconstructed Brentford works of the Gas Light and Coke Company shows the extent to which mechanical handling of material has been adopted.
The Operating Temperatures of Cast Iron and Aluminium Pistons in a 12-Inch Bore Oil Engine
Authors: Baker H. Wright
Published: October 2007

The engine used for these tests is of the single-cylinder vertical Diesel type, having a 12-inch bore and 18¼-inch stroke and running at 250 r.p.m. Temperatures have been measured at nineteen points on a ribbed “jam pot” cast iron piston, at twenty-three points on a “mushroom” type aluminium piston, and at fourteen points on a cast iron piston with a conical head support. Temperatures have also been measured at eight points on the cylinder liner. A description is given of the pistons and special testing apparatus. The influence of subsidiary junctions in the thermocouple leads, which led to some discussion following Dr. Mucklow's recent paper on piston temperatures,† has been studied. Errors, varying with engine output and amounting to as much as 29 deg. C., have been measured where no compensator was used.

The effects of the temperature of the liner and of the jacket water outlet on the pistons have been measured, and are discussed. The conclusions are in general agreement with those of Dr. Mucklow except such as apply to the central portions of the heads, where the great differences of area exposed to flame lead to remarkably divergent results.

The temperature distributions throughout the pistons are considered, and a quantitative estimate is made of the value of the neck, ribs, etc., when these are considered as heat channels. The radial temperature differences recorded for the aluminium and cast iron pistons and for the piston tested by Dr. Mucklow, are roughly in the ratio of 1/5½/19. The effect of varying the engine output has been studied, also the time required to warm up the pistons, the light alloy reaching its maximum temperature in approximately half the time required by the cast iron.

A decrease in the number of rings from five to three is shown to have very little effect except in reducing the fuel consumption, while rings of forged “Y” metal slightly reduce the temperature of the piston. The effect of totally enclosing the piston shows that only some 2 per cent of the heat received is normally lost to the air circulating within it.
Force Fits and Shrinkage Fits in Crank Webs and Locomotive Driving Wheels
Authors: Coker E. G. , Levi Miss R.
Published: October 2007

This experimental investigation relates to a general method of measuring stress distribution when force fits and shrinkage fits of the plane stress type are employed in engineering practice. Important cases occur in the webs of built-up crankshafts for locomotives and Diesel engines. When the latter are of high power and short stroke, so that crankshaft and crankpins are large and relatively close together, the initial constructional stresses are shown to attain high values.

More complicated cases, from an experimental point of view, occur in the driving wheels of locomotives with a tyre shrunk over a wheel centre having a crank and balance weight integral therewith, while the main axle and crankpin are forced or shrunk in. Such a case is examined with reference to a driving wheel of the London Midland and Scottish Railway locomotive Royal Scot, and the stress distributions measured in various parts of a model of it are described in detail.
Bauer-Wach Exhaust Steam Turbines
Authors: Crossley E.
Published: October 2007

In 1927–8 two cargo ships of roughly 11,000 tons displacement were built by Messrs. R. and W. Hawthorn, Leslie and Company for the Booth Steamship Company of Liverpool. Originally of identical design, the plans of S.S. Boniface were altered during construction to include a Bauer-Wach exhaust steam turbine, whilst S.S. Basil was built as originally designed with a triple-expansion engine only. Builders' trials on S.S. Boniface proved the turbine to give a reduction in coal consumption of 24·5 per cent.

The paper adds to the facts already known about this type of installation some information regarding reliability and economy in actual service. Following a general description of the propelling machinery and auxiliaries of the two ships, and a more detailed description of the exhaust steam turbine, gearing, hydraulic coupling, and control system of S.S. Boniface, notes are made regarding the general running and the troubles experienced with the extra equipment. Particulars of two trials at sea under normal conditions on S.S. Boniface are given, and finally, a coal consumption comparison on a yearly basis between the two ships is shown to give a saving of 15·9 per cent in favour of S.S. Boniface at the age of four years.
Air Swirl in Oil Engines
Authors: Alcock J. F.
Published: October 2007

Swirl, or rotation of the air charge, is increasingly popular as an aid to fuel distribution in Diesel engines, but as yet little is on record as to the principles of its production and use. On certain types of engine it is possible to mount a “swirl meter” or freely rotating vane within the combustion chamber, and thus by motoring the engine to obtain a measure of the swirl rate. From such experiments and from theoretical considerations, one can draw certain conclusions, and although these are directly established only as regards one particular combustion system, indirect evidence suggests that they have a much wider application. The most important conclusion is this, that with the combustion system in question there is an optimum “swirl ratio,” or number of revolutions of the vane per minute divided by the number of revolutions of the engine per minute which gives the best performance, whatever the engine size, speed, or load, and which is, in fact, characteristic of that combustion system. It seems probable that the same rule applies to other swirl systems.

In most cases the “swirl ratio“ is roughly constant over a wide speed range. This means that if this ratio is made correct at one speed, it will not be far wrong at any speed within the working range, a fact which accounts for the popularity of swirl type engines in vehicle and other variable-speed services.

The primary effect of swirl is that of winnowing the fuel spray, blowing away fine spray and burnt gas, and giving the heavier particles access to fresh air. There are, however, important secondary effects of which the causes are not known with certainty.
Piston Temperatures in a Sleeve Valve Oil Engine
Authors: Baker H. Wright
Published: October 2007

The paper describes tests on a Mirrlees-Ricardo sleeve valve engine of inches bore, running at speeds up to 1,400 r.p.m. The pistons used were: (1) a simple piston of cast iron; (2) a piston with tapered head section, cast in “L8” alloy; and (3) a heavily ribbed and strutted piston of “Y” alloy.

A robust form of thermocouple gear which has been devised is described in the paper, and the probable errors are discussed. The temperatures attained by a number of points in each piston are shown for various conditions. The effect of the sleeve is much less than might be expected. The rates of heat reception by the central and outer portions of the piston head differ considerably owing to the vortex type of combustion chamber used. Values of these rates have been estimated for different loads and speeds. The alloy pistons become warm in about half the time required by the cast iron piston.

Piston temperature appears to be a linear function of engine speed, the alloy pistons showing an increase of 42 deg. C. at the centre when the speed was increased from 800 to 1,400 r.p.m. at constant brake mean effective pressure. The temperatures of the lower edges of ribs of moderate depth were only 10–18 deg. C. cooler than the under surface of an unribbed piston. Distortion of the pin seatings due to the expansion of the struts must be very slight.

With normal water circulation and a constant temperature of water supply, piston temperatures in this engine are almost independent of the final temperature of the water.
Ventilation with Air Conditioning in Modern Buildings
Authors: Dolby E. R.
Published: October 2007

It is only comparatively recently that the realization of the desirability of a supply of pure air in buildings has been put into practice. In the early attempts to improve the air conditions in buildings it was thought that the mere admission of external air in sufficient quantity might suffice, but that was soon found to be inadequate. The ideal condition of the air suggested by the author is a temperature of 60 deg. F., a relative humidity of 50 per cent, and not more than 6 or 7 parts per 10,000 by volume of carbon dioxide. The air treated should also have dust, fog, and deleterious gases removed.

The author describes mechanical means for air conditioning and indicates the method of calculating the amount of conditioned air required in any given case. Examples of some typical installations are also illustrated. Filters for the removal of dust are of special importance in certain industries. Dry filters are very effective, but are expensive. In most cases the use of a viscous filter suffices.

The paper concludes with descriptions of various types of instruments for measuring humidity, a special type of centrifugal refrigerator for cooling the air delivered into buildings which uses dichloromethane as a refrigerant, and apparatus for ozonizing the air supply.
The Development of a Machine for High-Speed Testing of Materials
Authors: Lean R. J. , Quinney H.
Published: October 2007

The paper contains an account of a research into the effect on metals of different speeds of fracture, using a specially designed high-speed testing machine which is described in detail. The experiments were conducted both in this machine and in a 5-ton variable-speed autographic tensile machine, on five steels, the rate of loading being varied for each. With the high-speed machine toughness, ductility, time to produce fracture, and the stress-strain curve were obtained. The results of these combined tests, given in tables and graphs, show that there is a marked increase in stress due to higher speed of testing; and also that the work required to cause fracture increases with the speed. For mild steel the stress at the initial yield point was found to be in excess of that at the maximum point, when the speed of testing was increased the ductility did not appear to suffer.
Shoe Machinery
Authors: Cooper B. P.
Published: October 2007

Shoemaking is a very ancient craft, but it is rather less than a century since machinery was first used for the purpose, though in 1810, when the need arose for large quantities of boots for the troops engaged in the Napoleonic Wars, the elder Brunei invented the first riveting machines, which attached the uppers to the soles by nails which were driven and clenched.

A number of methods of construction are commonly employed, and the Goodyear welted process is described in the paper in some detail. Attention is then directed to some of the mechanical problems which have been solved in the design of the various machines used. These include a single-revolution clutch capable of stopping the machine with an accuracy of a few degrees of a revolution, and devices for selecting, separating, and feeding such loose articles as tacks, nails, and eyelets.

The outsole lockstitch machine is described in detail as an example of what has been accomplished by way of speed and quality of the product. The machine sews at the rate of 1,000 r.p.m. The automatic edge setting machine is also dealt with in detail on account of the arresting feature which might be called its “sense of touch”.
Friction and Heat Transmission Coefficients
Authors: Cope W. F.
Published: October 2007

The work described in the paper was carried out to determine simultaneously the friction and heat transmission coefficients of metal pipes of various cross-sections. A technique has been worked out and apparatus constructed for the simultaneous determination of the friction and heat transmission coefficients of the central portion of a pipe through which a fluid is flowing. With this apparatus, and with water as the working fluid, tests have been carried out upon a series of drawn copper pipes whose cross-sections varied from circular through square, to rectangular with sides in the ratio of 8/1; in addition two drawn brass pipes, one of which had had its internal surface artificially roughened, have been tested. The extreme values of velocity and Reynolds number are in the ratio of about 300/1; the maximum values being about 340 cm. per sec. (11 ft. per sec.) and 30,000 respectively. The friction coefficient of the rough pipe under isothermal conditions has been determined for values of the Reynolds number up to 50,000, using air as the working fluid.

The observations made have been reduced by the method of dimensional analysis and the following conclusions drawn:—

(1) That the results of the heat transmission tests on the various pipes can be correlated on the basis of the hydraulic diameter.

(2) That an increase in friction coefficient is not necessarily accompanied by an increase in heat transmission coefficient.

(3) That the friction coefficient under heat transmission conditions is the same as that under isothermal conditions if the viscosity in the former case is that pertaining to the wall temperature of the pipe.
Exhaust Systems of Two-Stroke Engines
Authors: Farmer H. O.
Published: October 2007

Crankcase-scavenge two-stroke engines have always been fitted with a large expansion chamber immediately outside the exhaust ports, but this is by no means essential, as such engines will operate very satisfactorily with a plain exhaust pipe. The length of this pipe is most important and has a controlling influence on the scavenging of the cylinder and the performance of the engine. Even when an expansion chamber is used in the exhaust system, the length of exhaust pipe still has a very marked effect on engine performance.

It has been found that certain arrangements of this combination of expansion chamber and pipes completely upset the performance of the engine, whilst others improve the performance, but it is possible to calculate the “equivalent length” of any system of this nature, and so arrange matters that the exhaust system is a help rather than a hindrance to the engine. Though certain results have not been satisfactorily explained, the tests carried out do give a fairly clear indication of the way in which the engine performance is affected by the variations in pressure in the exhaust system.

The concluding section gives a description of the principle on which the self-induction engine works, and indicates how use is made of the pressure variations or oscillations in the exhaust pipe to scavenge the engine cylinder, resulting in the complete elimination of the air pump on a two-stroke engine.
Engineering Problems Associated with the Improvement of Temperature and Humidity Conditions of the Atmosphere in Mines at Great Depths
Authors: Dobson J. H. , Walker W. J.
Published: October 2007

The subject is very complex and a great deal of research has been devoted to it on account of its great economic importance. The magnitude of the problems involved is shown by reviewing underground conditions on the Witwatersrand goldfields. Consideration of the limiting air conditions underground enables a specified mine-cooling problem to be enunciated.

The final section of the paper reviews the various methods that have been tried for cooling the air in deep mines; some have been wholly or partially given up and some have survived. In particular, the possibilities of meeting requirements on a large scale have been analysed. Reference is made to cooling schemes which have been inaugurated on the Witwatersrand goldfields during the past two or three years. An analysis sets forth the relative merits of water, brine, and air as media for cooling deep mines, and a comparison of cooling plant performances and costs is made on the basis of: (1) vapour refrigerating plants on the surface and underground, using air and water respectively as cooling media, and (2) compressed air refrigeration.
The Design and Operation of a Modern Blooming Mill
Authors: Cartwright W. F.
Published: October 2007

As an introduction to the visit of the members of the Institution to the Cardiff Works of Messrs. Guest Keen Baldwins, Ltd., the paper has been written to describe the blooming mill, and to indicate some of the reasons governing the adoption of this particular layout. It refers to some of the troubles experienced in operation and how they were overcome.

Rapid output of blooms is the result of several factors, ample heating furnaces close to the mill, good roller gear and manipulators, rapid reversal and screw-down gear, good shears, and the general robust construction of the mill —all of which are dealt with in detail in the paper.
First Report of the Research Committee on High-Duty Cast Irons for General Engineering Purposes
Authors: Pearce J. G.
Published: October 2007

The report is presented in three parts. Part I reviews the development of high-duty cast irons during the past fifteen years and relates them to the material traditionally used. This is illustrated by results given in Part II, derived from materials actually supplied by manufacturers and designed to show the present state of the art. When complete, these records will form the basis on which a major portion of the Committee's programme will rest, the service trial of selected materials in appropriate engineering applications. The remaining portion of the programme consists in the preparation of materials covering the whole range of cast irons and the determination of their mechanical properties. The first results of this are given in Part III, and it is intended, when the range is completed, to select materials which show sufficient promise for submission to a complete range of mechanical tests. In the meantime, it is hoped that discussion will assist the Committee in its future work.
The Effect of Certain Factors on the Izod Value of Weld Metal
Authors: Schuster L. W.
Published: October 2007

This research was carried out to obtain data on the application of the Izod test to non-alloyed weld metal. In general it was found that a good-grade refined weld metal, owing to its fine grain structure, behaves on Izod test much as an alloy steel hardened and tempered at say 650 deg. C. The extent to which the Izod value of such a weld is lowered by the presence of unrefined metal of any given depth was studied. To allow the start of the crack to be nearer than usual to the surface of the specimen, experiments were made on specimens with the notch depth reduced from 2 to 1 mm., the height of specimen required to give an equivalent result being determined for a good-grade refined metal. Results from specimens, both longitudinal and transverse, with notches at the various sides were compared, also the results from square and round specimens. A form of representative all-weld-metal specimen was devised that allowed the Izod results to be more truly representative of a test on a welded joint. The effect on the test result of varying the plate thickness, as well as the interval of time between the laying of the runs, was studied, also the effect of constraining the joint while being welded, some additional comparative experiments being made on rigidly constrained massive welds, chilled with water during deposition. The effect of a low-temperature annealing treatment on the Izod value was determined for several good-grade metals.

To obtain data on the liability for results to vary according to the temperature of the test house, tests were made on chosen grades of weld metal, completely refined and completely unrefined, in each of two states of heat treatment.
Identification of the Source of Deposited Matter
Authors: Owens J. S.
Published: October 2007

When complaints of a smoke nuisance arise it is very important to be able to identify the source. The aim of the paper is to indicate possible methods of overcoming the difficulties of correct identification. Consideration is given to the rate of settlement and the terminal velocity of dust particles, and the application of the physical laws governing deposition. The author has used successfully a method of measurement involving the arrangement of series of gauges in rows extending radially from the suspected source, observations being made with due regard to the prevailing winds. Another method is particularly applicable to the measurement of dust emitted from pulverized coal furnaces, and is based on the tendency of the particles emitted from such furnaces to fuse whilst suspended in the furnace during combustion.

Directional deposit gauges have been tried, but so far have not been very successful. The basic idea is to provide a gauge which will separate the deposits from different directions, and various forms have been experimented with.
The Combustion Gas Turbine: Its History, Development, and Prospects
Authors: Meyer Adolf
Published: October 2007

By “combustion gas turbine” is meant a turbine actuated by the steady flow of the products of a continuous combustion under pressure in a combustion chamber. Inventors appear to have been at work on the gas turbine since 1791, the original attractions of the proposal being its simplicity and the elimination of the reciprocating motion of the early steam engines. Simplicity remains the principal advantage of the gas turbine, though the first applications have been made possible by the needs of special chemical processes, such as the Houdry cracking process. The efficiency attainable under present conditions is 17–18 per cent, but this would be increased to 23 per cent if the gas inlet temperature could be raised from 1,000 to 1,300 deg. F. The proposed new fields of application of the gas turbine include locomotive and marine propulsion, blast furnace plants, and the power supply for wind tunnels.
New Boiler Plant at Dalmarnock Power Station
Authors: Young W. E.
Published: October 2007

The plant was installed at the Glasgow Corporation Electricity Department Generating Station at Dalmarnock during 1936–7, and consists of six Yarrow water-tube boilers, each capable of evaporating 200,000 lb. of steam per hour at 625 lb. per sq. in. working pressure, superheated to 850 deg. F. The boilers are the largest in Scotland and are typical of modern practice in steam generating plant for large power stations. The description of the plant includes particulars of the boiler drum scantlings, tube sizes, and spacing; the effect of bending on the drum design; the pipe connexions between water-wall headers and boiler; the preliminary heating arrangements; and the automatic interstage control of steam temperature. A table gives results of tests at three different loads, and curves of fuel consumption are included. Particulars are also given of the time taken to execute the work, and the paper concludes with some operating notes.
Second Report of the Pipe Flanges Research Committee
Authors: Tapsell H. J.
Published: October 2007

The research † has continued to follow the main lines of the programme originally laid down by the Committee, with an important addition, namely that relating to the study of the creep relaxation of model flanges. Some sections of the work are still incomplete; in such cases the data so far obtained are recorded and discussed, but final conclusions must be postponed until the research is terminated.

The present report deals with the following sections of work:—(I) an investigation of conditions on the joint under which tightness is maintained at room temperature (p. 433); (II) an investigation of the behaviour of compressed asbestos packing materials under certain conditions of loading and temperature (p. 437); (III) the completion of the examination of the properties of the materials used in the bolt assembly tests (p. 439); (IV) experiments on full-scale bolted flange joints under conditions of high temperature and pressure (p. 441); and (V) creep relaxation tests on model flanges (p. 453).
Production Research in Its Application to the Machine Shop of a Dockyard
Authors: Schlesinger G.
Published: October 2007

The author was entrusted with the task of reorganizing the machine shops of the Wilton-Fijenoord shipyard at Rotterdam-Schiedam in 1936 and of raising their output considerably. It was uneconomic to replace all the old machines; machines which were not adaptable were gradually eliminated, whilst those capable of having their speed doubled and of working to precision limits were rebuilt.

All hand-grinding machines were removed from the shop and collected in a central grinding department, and the number of materials was reduced from 50 to 14 machining groups. For each group the tool angle, size and shape of tip and shank, and the tool steel to be used were fixed so that the optimum output coincides with the minimum cost of materials and repairs. To ensure that the instructions given by the rate fixer are followed by the workmen, an engineer continuously inspects the work produced. A form was drawn up, and is reproduced, giving all the data required by the operator for carrying out the rate fixer's instructions.
Lightweight Passenger Rolling Stock
Authors: Stanier W. A.
Published: October 2007

This paper makes no attempt to compare British and American practice because of the wide difference in operating conditions prevailing in the two countries. Developments which have taken place in the last seven years on the London Midland and Scottish Railway are described, showing the improvements in the conventional British passenger coach. This originally consisted of a separate riveted steel underframe and timber-framed body, but to reduce weight without sacrifice of strength, welding and high-tensile steel have been employed and timber gradually eliminated. This has resulted in an increasing identification of the underframe and body which has produced an all-steel coach giving a weight of about 500 lb. per passenger seat. Means adopted include the body side and underframe combined into the form of a Vierendeel truss, the design of which is briefly described, together with the method of calculating the stresses in the different members. On the constructional side, the layout of the shops and the special presses and tools are dealt with. A method of unit assembly has been adopted and both spot and arc welding are largely used. Details are given of the erection into a complete coach, and of the overload tests made on the finished structure. Particulars are given of the savings in weight attained, and the paper concludes with suggestions as to the direction in which further progress may be sought in the future.
The Trend of Air Transportation
Authors: Allen Edmund T.
Published: October 2007

The year 1925 marked the beginning of air transportation as an industry. Since then it has advanced through successive stages of growth and development until to-day, as the author believes, air transport is in the state of transition between the pioneering period and that of mature growth. Airway mileage by scheduled air transports in the United States has increased from a total of 2,000,000 miles flown in 1926 to 90,000,000 in 1939. Air passenger-miles in 1938 aggregated 600,000,000. In this paper the author reviews the technical developments in aircraft and improvements in airway operation which have made possible this phenomenal growth. Every phase of this development which has played a part in the successful and safe operation of the airway systems of the present day is treated comprehensively in order that an understanding may be gained of the future possibilities of air transport and the lines along which it will advance.
The Yield of Mild Steel with Particular Reference to the Effect of Size of Specimen
Authors: Morrison J. L. M.
Published: October 2007

The paper is a description of an investigation undertaken to determine, by tests under various conditions of uniform and non-uniform stress distribution, the criterion of yield in specimens of mild steel. Apparatus is described for heat-treating the material after machining in such a manner as to avoid surface decarburization, and for determining the stresses at yield of specimens tested in tension, compression, flexure, torsion, and combined tension and torsion.

The results show that the material used is uniform and isotropic. No differences are found between the yield in tension and compression. Tension tests on thin tubes and on solid specimens of varying size indicate a progressive change from single-crystal stress-strain characteristics to the normal characteristics of polycrystalline material. Tests in combined tension and torsion give results which accord with the theory of yield at a critical value of the shear strain energy stored per unit volume of the material, but this is shown to be entirely due to the size of the specimens tested. In all cases of nonuniform stress distribution, the yielding is shown to depend on the specimen size, being delayed until a shear stress not less than the shear stress at yield under uniform stress is applied to a thickness of material of the order of a few crystal diameters.
A Photographic Study of Fluid Flow between Banks of Tubes
Authors: Wallis R. Pendennis
Published: October 2007

The paper describes the flow in nests of tubes as disclosed by photographs of moving specks of aluminium dust sprinkled on the surface of flowing water. Details of the necessary water speeds, illumination, camera exposure, and other relevant conditions are given in the first part of the paper, while later the effects of transverse and longitudinal pitch in both parallel and staggered nests are investigated and illustrated with photographs.
The Lubrication of Steam-Turbine Driven Electric Generators
Authors: Cowlin F. J.
Published: October 2007

The paper briefly reviews the problems arising in, and the system employed on, the lubrication of large modern steam-turbine electric generators. A description is given of the general layout, enumerating the various components and the reasons for their inclusion. The general qualitative relations governing the operation of film-lubricated bearings are briefly stated; published results of full-scale experiments on commercial types are compared; and a simple method is given for estimating the power absorbed, based on practical experience. Various types of oil pumps, and the principles adopted in fixing their capacity are described, the results on gear type pumps being shown by several curves.

The development of modern forms of oil-cooling apparatus is traced, attention being given to factors affecting the rate of heat transmission obtainable; a series of tests carried out on a modern type are described. Curves showing the relation between heat transmission rates and oil and water velocities obtained from these tests are reproduced. The disposition, design, and capacity of oil tanks are discussed, together with the practical aspects of piping layouts. The concluding section deals with the properties of lubricants, factors contributing to deterioration, and methods of purification commonly employed.
Recent Developments in the Use of Hydraulic Power
Authors: Town H. C.
Published: October 2007

Hydraulic power development may be divided into two groups, first, one in which mechanical and civil engineering developments combine to use natural forces for power production, and second, the phase of hydraulic power development which it is proposed to consider, namely that appertaining to mechanical production and automotive traction. Until recent times, no phase of engineering development has remained comparatively stationary for so long a period as that of power operation by hydraulic means. It is true that there has always been a field where the characteristics of hydraulic power were essential, but in the more recent drawing and stamping industries, hydraulic operation was unable to compete until developments in collateral fields removed all disadvantages.

Prominent amongst the developments to this end, has been the introduction of the variable-delivery pump to each machine, as against the central pumping station. These self-contained units are available with a normal maximum pressure of 1,000 lb. per sq. in., but in certain cases no less than 5,000 lb. per sq. in. can be obtained.
Refrigerator Performance: An Investigation into Volumetric Efficiency
Authors: Giffen E. , Newley E. F.
Published: October 2007

The paper describes experiments carried out on an ammonia-vapour compression refrigerator, with the object of investigating the conditions affecting the volumetric efficiency of the compressor. The most important part of the investigation deals with the effect of the condition of the vapour at the suction valve, over a range from about 0·75 dry to 45 deg. F. superheat, on both the actual and the indicated volumetric efficiencies. The actual volumetric efficiency drops about 20 per cent between the superheated and the wet conditions, but the indicated efficiency shows little variation. The results lead to the conclusions that the decrease in volumetric efficiency is due to condensation of ammonia on the cylinder walls during the compression and delivery stroke, and that the temperature of the cylinder wall is the critical factor determining the vapour condition at which the drop in efficiency begins. Other variables investigated were the condenser and evaporator pressures, and the compressor speed.
Power Transmission by Belting
Authors: Jagger J. G. , Sykes F.
Published: October 2007

During experimental work on flexible belts running on pulleys of small diameter, the loss of speed of the follower arising from the elasticity of the belt was observed to be considerably greater than would be normally expected. It was also noticed that this loss of speed depended on the mean tension of the belt and the diameter of the pulley. The usual type of belt material does not follow a linear elastic law for strains in the direction of its length, the elastic modulus being relatively low at low tensions and when in compression. On the assumption that compressive stresses can be neglected, the resulting stress distribution is found to account partly for the experimental results. In addition the material has a relatively low transverse compression modulus, and the surface compression causes an additional slip loss which would be negligible with an isotropic material in all practical cases. The examination is applicable to V-belts when the effects producing radial movements are of greater importance because of the amplification by the groove angle. For both kinds of drive the relative influences of the component losses on efficiency are discussed, and conclusions can be drawn on the suitability of materials for small pulley drives.
The Friction and Heat Transmission Coefficients of Rough Pipes
Authors: Cope W. F.
Published: October 2007

In a previous paper (Cope 1937)† an account was given of the simultaneous measurement of the heat transmission and friction coefficients of a series of smooth pipes of various shapes of cross-section. The results formed the first section of a comprehensive research into the problem of heat transmission. The present paper, which describes the results of tests on rough pipes, forms the second section. Three pipes were tested, their internal surfaces being artificially roughened by a special knurling process which produced a series of pyramids geometrically similar in form but varying in absolute size from pipe to pipe. The roughness ratios (radius of pipe/height of pyramid) were approximately 8/1, 15/1, and 45/1. The apparatus used was basically the same as that used in the previous tests; the working fluid was water, and the Reynolds number ranged from 2,000 to 60,000. The results indicate that when fully turbulent conditions are established the roughness has very little effect on the heat transmission coefficient, but that in the transition region between laminar and fully turbulent flow, the roughness may increase that coefficient to considerably more than its value for a smooth pipe; and that the heat transmission graphs for the three pipes are in better agreement if shearing force velocity is used instead of mean velocity, in forming the non-dimensional parameters used for plotting purposes. The broad conclusions from the practising engineer's standpoint are (1) for a given pressure drop across a heat transmission apparatus more heat will be transmitted if the pipes be smooth than if they be rough; (2) the velocity of the working fluid will, of course, be greater with smooth pipes; and (3) the smooth pipe is more efficient if the comparison is made on a basis of heat transmission for equal power.
The Creep Recovery of a 0.17 per cent Carbon Steel
Authors: Johnson A. E.
Published: October 2007

Since 1876 occasional interest has been shown by investigators in the phenomenon of creep recovery, or what has been sometimes referred to as delayed elasticity or subpermanent elasticity. This may be defined as the negative strain, increasing with time, which occurs when a specimen strained under load, as in a creep test, is unloaded and maintained at its working temperature. Theories have been advanced to account for the phenomenon, but sufficiently full data have not been obtained for any of the commonly used commercial materials to provide means of checking the theories. The present paper, for the case of a 0·17 per cent carbon steel, investigates the relation between recovery and the stress, temperature, period of test, and strain, in the creep test preceding the recovery, and presents data by means of which the existing theories are compared.

Creep and recovery tests were made in creep units capable of measuring creep rates of the order 10–8 in. per in. per hour, the test temperature being maintained constant to ±0·5 deg. C. At each of the temperatures 425, 455, and 485 deg. C., groups of creep tests—continued to periods of 0·2, 2, 20, and 145 hours, respectively—were made, each group consisting of tests at three different stresses. Each test piece on unloading was allowed to recover for 100 hours. One or two similar tests were also made at 350 and 550 deg. C. In addition, at 425, 455, and 485 deg. C., groups of creep tests were made, and were carried to the stage of minimum creep rate; the test piece was then unloaded, and allowed to complete its recovery. These groups of tests also consisted of tests at two or three stresses.

The author discusses the relation of creep recovery to stress, temperature, period of creep, and strain in the initial creep test, and finally tabulates his principal conclusions which, he points out, apply only to the steel tested, and are not to be taken as generally true for other materials. A bibliography is also included in an Appendix.
I. Report on Austenitic and Martensitic Special-Duty Cast Irons
Authors: Pearce J. G.
Published: October 2007

The First Report of the Committee* outlined briefly the development both of high-duty cast irons used by engineers for their superior strengths, and special-duty cast irons used mainly on account of other properties. As a consequence of the war, a demand has arisen among engineers and users for further information on special-duty irons, which are being used both as substitutes for other materials in urgent demand and for new applications arising out of the unusual conditions now prevailing. The Committee therefore decided that monographs should be prepared for the purpose of providing engineers and users with information available, and the present publication covers two relatively new types of special-duty cast iron—the austenitic and martensitic irons. To avoid repetition in introductory statements relating to the character of these irons, the two monographs are prefaced by a description of the types of cast iron available, which it is hoped may prove generally useful as well as a convenient summary of the relationship of the two types to each other and to the other cast irons in general use.
A New Mathematical Method for the Solution of Film Lubrication Problems
Authors: Christopherson Derman G.
Published: October 2007

The paper applies the technique of the “relaxation” method to the problem of fluid-film lubrication. It is found that a solution to Osborne Reynolds's governing equation can be obtained by this means in all cases of practical importance. The method also renders possible a new treatment of the difficulty presented by the occurrence of divergent films in journal bearings.

The problem is shown to be tractable even when viscosity is correctly treated as a function of both temperature and pressure; moreover, as a part of this treatment, means of estimating the temperature distribution over the bearing surface are provided.

A numerical example is used to illustrate the modifications in the solution resulting from viscosity variation.
Balancing of Locomotive Reciprocating Parts
Authors: Cox E. S.
Published: October 2007

Since the British Bridge Stress Committee's report† of 1928, an increase has occurred in the speed capacity of locomotives. After showing how the recommendations of that Committee have been met in modern British locomotive design, the effects of higher rotational speeds are discussed, and tests with the lifting of coupled wheels off the track at maximum speeds and with various proportions of reciprocating balance are described.

Since the necessity may arise for reducing hammer blow values still further to meet civil engineers' requirements, the possibility of reducing or eliminating the amount of reciprocating balance becomes important. The effect of this factor on the locomotive itself is discussed theoretically, expressions being given for the amplitude of the resulting horizontal and lateral oscillations.

Available practical evidence in support of the theoretical considerations is described, and conclusions are reached regarding the conditions under which it is still necessary for locomotive reciprocating parts to be balanced.
The Axial Vibration of Diesel Engine Crankshafts
Authors: Poole Ralph
Published: October 2007

The paper describes an investigation carried out to determine the magnitude of axial vibration of engine crankshafts, with the object of establishing that axial resonance may occur within the normal running range of an engine.

The author gives the results of tests on various makes of engine using a portable vibrograph to record the axial movement of the crankshaft. In some cases the torsional osculation was measured simultaneously by means of a universal vibrograph. The vibrograph records show that at certain speeds some engines are subject to a very marked increase in axial vibration of a magnitude consistent with a condition of axial resonance.

The author describes a test in which the natural frequency of axial vibration of a crankshaft is determined experimentally by using an a.c. electromagnet as a means of applying an alternating force.

Expressions are derived for calculating the axial deflexion of a crankshaft due to the piston load, and also for calculating the axial deflexion under an axial load. It is suggested that the relation between these two deflexions determines the magnitude of the axial force set up by the piston loading.

From a series of load-deflexion tests, carried out on a number of crankshafts, the author determines the value of empirical factors to be used in estimating the axial stiffness.
The Properties and Mode of Rupture of a Molybdenum and a Molybdenum-Vanadium Steel, Judged from Prolonged Creep Tests to Fracture
Authors: Tapsell H. J. , Bristow C. A. , Jenkins C. H. M.
Published: October 2007

The accompanying report deals with the nature of the failure at high temperatures of certain alloy steels, which are being used to replace carbon steels, and indicates the conditions of use under which the development of intercrystalline cracking can be avoided. Investigations are being continued with a view to finding steels of high creep strength, in which the onset of intercrystalline cracking can be displaced to higher temperatures.
Distribution of Boiler Load
Authors: Kaufmann Paul G.
Published: October 2007

The paper deals with the load distribution between a number of boilers operating in parallel, with a view to obtaining minimum fuel consumption. The application of the theory of minima leads to a graphical solution, and it is demonstrated that maximum plant efficiency can generally be obtained only when all boilers share in the load fluctuations to an extent depending on the input-output characteristics of the various boilers and on the momentary load. The division of a plant into groups of boilers operating at base load and fluctuating load, respectively, is generally not economical. Automatic boiler control not only increases the operating efficiency of the individual boiler but can be used also for maintaining the most economical load distribution between the units, and thereby also raises the efficiency of the plant as a whole.

The paper also discusses how many and which units should be used to cover a given load range, and when a boiler ought to be banked or connected to the line again. This depends upon the ratio between standby and operating periods; but generally it will be more economical to operate all boilers down to their minimum load than to bank some of them.

The same principles of load distribution can be applied to the parallel operation of any kind of machines other than boilers.