bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuel Economy in Petrol Engines
Authors: David W. T. , Leah A. S.
Published: October 2007

Charts are given in this paper from which may be found the indicated thermal efficiencies, the fuel consumption per indicated horse-power-hour, and the mean effective pressures which are practically attainable in a compact combustion-chambered petrol engine of any bore between 3 inches and 8 inches when running at any compression ratio between 4/1 and 9/1 and at any speed from 1,000 r.p.m. upwards on an octane, ethyl alcohol, or benzene-air mixture of any strength between 20 per cent weak and 20 per cent rich. From these charts similar information in regard to any mixed petrol may be deduced with fair accuracy.

The performance of actual engines is compared with the attainable performance in the light of views, given in some detail, relating to phenomena associated with the working fluid and the combustion of the charge. The conclusion is that improvement in charge mixing within each engine cylinder would lead to better performance. Characteristic merit and demerit curves are suggested which appear to be capable of yielding useful information in regard to the functioning of engines.
Fuel Injection in Oil Engines in Relation to Combustion
Authors: Green G. W. A.
Published: October 2007

The object of the paper, which deals with the jerk pump injection system, is to show the relationship between the design of fuel injection equipment and the design of the engine on which it is used.

First the nozzle is considered as an orifice, in its relation to the combustion chamber, and an account is given of the features of hole type and pintle type nozzles. The action of the differential needle valve is then discussed, and particular reference is made to the design features necessary to ensure quick action of the valve, with good “chattering”. The author then considers the design of “restricting” or “delay” type nozzles, and a description is given of the delivery valve of the pump. The need for “unloading” of the delivery pipe is discussed, together with various types of delivery valve and their action. The delivery pipe itself is treated with reference to ( a) determination of size of pipe; ( b) pipe surges and their effects; ( c) methods of dealing with surges. In addition the action of a pump plunger and barrel of the ported type is considered in relation to its effect on pump output at varying speeds, also the combined effect of pump plunger and delivery valve.

The author sets out the points to be considered in the selection of fuel injection equipment for a given engine. Basing his analysis on existing designs, he puts forward a classification of combustion chambers from the viewpoint of fuel injection. He shows that orifice diameter in hole type nozzles depends on the penetration required, and that the total orifice area is also dependent on the piston displacement per unit of time. The selection of a suitable pump to feed the nozzle is discussed, and the author arrives at specific ratios for assessing pump action in relation to the engine and the nozzle. Finally, consideration is given to the limiting capacity of an atomizer of given size, and to the release pressure in an atomizer and the maximum pressure of injection.
Properties of Steels as a Basis for Design for High-Temperature Service. Part I: Carbon Steels
Authors: Tapsell H. J. , Johnson A. E.
Published: October 2007

The paper gives a brief account of the influence of stress, temperature, and time on the behaviour of carbon steels of about 0·15 to 0·50 per cent carbon content, and provides data as a basis for design purposes. The data given are derived from investigations carried out at the National Physical Laboratory, largely on behalf of the British Electrical and Allied Industries Research Association.

Although practice has established satisfactory working stresses for carbon steels at moderately elevated temperatures—possibly up to 425 deg. C. (800 deg. F.)—it may serve a useful purpose to include herein particulars of the strength of carbon steels up to 800 deg. F. The chief purpose of the paper, however, is to assist the reader in appreciating the factors involved in estimating the useful strength of steels at higher temperatures extending to about 1,000 deg. F.
Fatigue Tests of Structural Steel Flats and Bars Cut from Butt-Welded Boiler Plate
Authors: Lea F. C. , Whitman J. G.
Published: October 2007

The paper describes the results of repeated stress bending tests to determine whether the resistance of welded plates to repeated stresses depends on the size of the plate, or in other words, if there is a “scale effect”; and to compare the results obtained from welded plates with those from plates with holes drilled in them. The tests were carried out in the bending machine‡ designed by one of the authors.

In the second§ and third‖ reports of the Welding Research Committee the results of repeated stress tests on -inch butt-welded plates and on 3-inch butt-welded plates had shown that from the smaller butt-welded plates a higher fatigue range from zero minimum stress had been obtained than from the 3-inch butt-welded plates. A detailed examination of the welds did not indicate a satisfactory explanation of the difference, and it appeared desirable, therefore, to make further tests on specimens of various thicknesses to determine whether the lower fatigue range was due to the size of the specimen.

The results given in the paper show that for specimens from 1 inch to 3 inches in thickness made in three different works no scale effect is indicated. The tests made on drilled plates confirm others previously carried out, and show that drilling a hole in a plate reduces the fatigue range load very considerably. The results from the thick welded plates show that with well-controlled welding, fatigue ranges for the welds as high as those from the black plate can be obtained.
Some Notes on Printing Machinery
Authors: Skeat W. O.
Published: October 2007

After a preliminary section dealing with type and type faces in general, and the methods of generating the matrices from which letters are cast, the author describes the machinery used in the two broad divisions into which the work of producing a printed page can be divided: ( a) composing and typecasting; and ( b) actual printing, or “machining”. The paper deals only with the machinery used in the production of the Proceedings of the Institution.

Composition is carried out on Monotype keyboard machines, provided with groups of keys, arranged like those on a typewriter; the keys when depressed cause perforations, varying with every key, to appear in a paper roll fed through the machine. The finished roll, looking like a pianola roll, is then “played” on the typecaster and the perforations in it form a code which virtually gives instructions for the fresh positioning of the matrix case for each letter cast. The galleys of newly cast type emerge from the caster, are divided into page lengths, and assembled as complete pages in “formes” which are then taken to the printing machines. The press used for this work is of the “two-revolution” pattern, printing the sheet during one revolution and delivering it during the next. The mechanism for reversing the bed is described, also the special arrangements for feeding the sheets to the machine.
The Physical Aspect of Steam Generation at High Pressures and the Problem of Steam Contamination
Authors: Davis R. F.
Published: October 2007

The constitution and the physical properties of boiler water are investigated with reference to the operating pressure. The process of evaporation at a submerged heating surface is examined and it is shown how nuclear boiling is the normal mode of evaporation, but that under certain conditions film boiling may take place. The size of the steam bubbles generated bears a definite relationship to the characteristics of the heating surface and the operating pressure. During migration from the heating surface to the free water level, the steam bubbles experience rapid growth at low pressures, but a negligible amount of growth at high pressures. The effect of bubble size on circulation is discussed.

At high pressures the steam bubbles are very small and the presence of salts in the boiler water tends to inhibit their coalescence. Small steam bubbles throw up minute drops of water upon disruption into the steam space. The height to which the drops rise above the water level depends on the operating pressure and the rate of steam release; the drops become entrained with the steam at a certain critical rating, causing wet steam. Foaming is another cause of wet steam and is found to depend on the physical state of the suspended solids in the boiler water. Mechanical priming and methods of preventing steam contamination by moisture and solids are also discussed.
The Mechanical Requirements of the Royal National Lifeboat Institution
Authors: Johnson P. H.
Published: October 2007

After dealing briefly with the historical and general aspects of the subject, the author touches on the disposition of lifeboats round the coast and the factors which govern this distribution. Details of the boats themselves and their equipment are not given, but the paper concentrates on the difficulties involved, and the methods and equipment employed, in launching from the beach.

Certain difficult beach conditions have been met by mounting the 11 tons of lifeboat and carriage on track units of the rigid girder type. Reference is made to the wheels employed in launching lighter boats in the past. Excessive rolling resistance made these wheels impracticable for soft beaches. The relationship between rolling resistance and the width and diameter of steel-tyred wheels is given, together with a description of the girdled wheels devised some forty years ago by Commander Gartside-Tipping, R.N. The development and construction of the girder track units now employed in place of wheels is fully dealt with.

The method of launching a lifeboat by tractor is described, and shows how necessary are extreme reliability and watertightness in the tractor employed.

The lifeboat “roadless” tractor is then described in detail and particulars given of the methods by which it is made waterproof. Special mention is made of gear for extracting the tractor from quicksand or mud pockets, and a résumé is given of the experience gained in this direction with tanks during the war of 1914–18. An alternative method to that adopted for waterproofing the tractor is referred to.

A summary is provided of the submergence and other tests to which the tractor is subjected and of the special precautions which are taken in service to prevent trouble arising from internal corrosion due to condensation. The paper closes with the possible applications in other directions of the experience gained with the machinery described.
The Dynamic Absorber and its Application to Multi-Throw Crankshafts
Authors: Bailey S. B. , Bulleid C. H.
Published: October 2007

The dynamic absorber is the special case of a tuned absorber in which the natural frequency of oscillation is directly proportional to the rotational speed of the shaft which carries it. Four typical absorbers are studied in detail; in each case, the tuning and amplitude equations are derived and, for the roller types, expressions are obtained for the maximum roller amplitudes which may be attained without the occurrence of slipping.

As with the simple tuned absorber, the dynamic absorber may be used to prevent resonance with one torque harmonic, and will operate satisfactorily so long as it is connected to the main system at the point of application of this exciting torque. There is therefore no difficulty in fitting such an absorber to a single-row radial engine in which all the exciting torques act at one crank throw.

An engine having a multi-throw crankshaft presents more difficulty, as it is necessary to determine how many absorbers to fit, and the manner in which the stabilizing torque is distributed between these absorbers. Such a case is fully analysed, and examples are given of the application of dynamic absorbers to a typical multi-throw aero-engine crankshaft. The method is quite general, and can be applied to any other type of engine as desired.
Heat Transmission in Surface Condensers
Authors: Petty Thomas
Published: October 2007

The paper deals with the resistance to heat flow on the steam side of surface condenser tubes, and begins with a brief reference to theoretical and experimental work on the subject.

The separation of the total resistance from steam to water into its component resistances and the estimation of the resistance from steam to tube by the remainder method is then discussed, an example of the procedure used by the author in the preparation of the paper being given in Appendix I.

The probable factors in the conditions of operation which produce the variations observed in apparent resistance to heat flow from steam to tubes, as estimated by the remainder method from the results of condenser tests, are then considered.

The validity of the assumptions made with regard to these factors is tested by a re-examination of the results of four well-known condenser tests in which the amount of air leakage was recorded. The conclusions and observations to which this examination would appear to give rise are then stated. An alphabetical list of references is given in Appendix II.
Munitions Labour Supply Organization
Authors: Denholm W. H.
Published: October 2007

The author reviews the effect of the war effort on the demand for skilled labour, and points out that the question of its proper distribution has been met by the establishment by the Ministry of Labour and National Service of an Inspectorate of Labour Supply, and Labour Supply Committees. The Inspectorate form the direct contact between the labour supply organization and the factories, and have the function of ensuring the efficient use and distribution of labour in essential industries. Their principal duties are to examine demands for skilled labour, taking into account any possibilities of the redistribution of skilled workers, the upgrading of semi-skilled workers, or the subdivision of processes. They also determine whether skilled labour can be released, and stimulate training by employers. Further duties are concerned with the Undertakings (Restriction on Engagement) Order, and the Conditions of Employment and National Arbitration Order, 1940. The author discusses the complex nature of the investigations which are undertaken in order to direct labour to work at which it is best used in the national interest. Where difficulties arise in the transfer of labour they are referred to the Labour Supply Committees, which deal with the general field of labour supply in their respective areas, and not only assess the relative urgency of demands for labour, but also stimulate arrangements for welfare and training.

A section of the paper deals with training in training centres, technical colleges, and in factories, as well as with the training of apprentices and women supervisors. The author concludes with some notes on Area Boards, and puts forward suggestions to manufacturers with the object of accelerating progress in the work of labour supply.
The Fundamental Principles of the Steam Ejector
Authors: Royds R. , Johnson E.
Published: October 2007

The main purpose of this paper has been to express experimental results in a form which reveals the fundamental principles for application to the design of ejectors. Notwithstanding the large losses of work energy in the nozzle, combining cone, and diffuser, the diffuser was found to obey the same laws of discharge as in convergent nozzles, although with a different constant.

At the best nozzle settings, if P is the ejector outlet pressure, the position at which the pressure reached the adiabatic critical value P c = 0·55 P occurred at nearly the same point in the diffuser at maximum efficiency for wide variations in the working conditions, and for different forms of combining cone and diffuser throat. Also, the calculated area a c of the stream at this point was practically independent of the same factors.

The position of the mouth of the nozzle had a predominant effect on the performance and efficiency, and the best nozzle positions were found to be nearly independent of the dimensions of the nozzle, the weight of steam and air flow, and the dimensions or form of the combining cone and of the diffuser throat.
The Regenerative Cycle: An Efficiency Basis having Special Reference to the Number of Feed Water Heating Stages
Authors: Horsman H. S.
Published: October 2007

The efficiency of the regenerative cycle may be defined as the ratio of the heat converted into work (in British Thermal Units per pound of steam) to the heat supplied to 1 lb. of steam in the boiler plant. Where feed heating is employed, however, the heat converted into work is less than the adiabatic heat drop as calculated from the initial and final states of expansion. The difference between these quantities is termed “unavailable heat” in the paper, and the efficiency is therefore given as the ratio of the adiabatic heat drop less the unavailable heat, to the heat supplied to 1 lb. of steam in the boiler plant.

The object of the paper is to illustrate the advantage derived from working in terms of unavailable heat. Values of this quantity are given, and the author provides a worked example showing their use. Appendixes I and II deal with investigations of the case in which the number of feed heating stages is infinitely great, i.e. the conditions for the ideal efficiency. The relationship of the ideal efficiency to other efficiencies corresponding to various finite numbers of feed heating stages is indicated.
Second Report of the Research Committee on High-Duty Cast Irons for General Engineering Purposes
Authors: Pearce J.G.
Published: October 2007

After the publication of the First Report in December 1938,† work was continued on alloyed cast irons in accordance with the Committee's programme. This work was in active progress when the outbreak of war directed the attention of the Committee to those matters within its province which would most assist the national effort. Chief among these was the necessity for making the fullest use of the national resources in phosphoric ores, and hence it was decided to provide engineers with a report on phosphoric irons. The present report is wholly concerned with engineering phosphoric grey cast irons, free from alloying elements, used in the as-cast condition and manufactured in the ordinary way. A further report will be made on alloyed phosphoric high-duty irons.
II. Report on Austenitic Cast Irons
Authors: Pearce J. G.
Published: October 2007

Austenitic cast irons may be regarded as bearing the same relation to ordinary cast irons as some of the stainless steels bear to the ordinary steels. Although more expensive, both in raw materials and manufacture, the austenitic cast irons have properties which mark them off as different from all other cast irons, particularly in their softness and ductility; high resistance to wear, erosion, corrosion and heat; non-magnetism and relatively high electrical resistance; low thermal conductivity and high thermal expansion. Their mechanical properties compare with those of a good engineering cast iron, but their softness and toughness make them readily machinable. They are readily welded. They are not susceptible to ordinary heat treatment, i.e. quenching and tempering, but nevertheless can be annealed at low temperatures with advantage. They can be cast white if required, and a simple thermal treatment such as annealing at 950 deg. C. for 30 minutes yields a metal with 2–3 per cent elongation in the cold. While the founding of these irons presents special problems, these can be overcome and the smallest castings can be, and are, successfully made in austenitic irons, down to -inch section; but if thin sections should be hard, they can be softened by the treatment given above. They melt at about 1,150 deg. C., a figure similar to that of the non-phosphoric cast irons, and have a specific gravity of 7·2–7·6.

The present report is intended primarily as a guide to the engineering properties of the austenitic cast irons, in order that engineers may use them to the fullest extent justified by their properties. The data presented are drawn from authoritative sources, and a list of the papers and reports consulted is given at the end. In general, the data are those of interest to the user rather than the maker, to the engineer rather than the metallurgist.
Bench and Field Tests of Vehicle Gas Producer Plant as Applied to Farm Tractors
Authors: Bowden A. T. , Freeth E. E. , Rutherford A. D.
Published: October 2007

During the past three years producer gas plants suitable for vehicles have been manufactured and marketed by several firms in Western Australia, to an extent that over seven hundred agricultural tractors in that State are now working successfully on producer gas. Australia as a whole, and Western Australia in particular, is fortunate in possessing large areas of hardwoods eminently suitable for making high-grade charcoal. As a consequence, producer gas development in Australia has been largely confined to the charcoal-burning type of producer.

The present investigations were undertaken by the Mechanical Engineering Department of the University of Western Australia under the direction of Dr. Bowden, then Associate Professor of Mechanical Engineering, the object being to obtain information relating to the performance of producer-powered tractors. Funds for the purpose were made available by the Commonwealth Government of Australia through the Council for Scientific and Industrial Research.

Experimental stations were established at Kellerberrin, and at Cranmore Park near Walebing. At the former, trials were conducted using two types of producer gas plant (the “Powell” and the “Herbert”), and two types of tractor (a “Case 12–20” and an “Allis-Chalmers” model “U”). Considerations of space allow of only brief reference to the trials carried out with the latter tractor. At the Walebing station a standard “Fordson 14–26” tractor was used in conjunction with “Powell” and “H.S.G.” producer gas plants. The results of the Kellerberrin trials are recorded in part I of the paper, and those of the Walebing trials in part II. A typical daily log sheet is reproduced in the Appendix.
The Utilization of Wood Refuse for Steam Raising
Authors: Gillham R. B.
Published: October 2007

The problem of utilizing or even disposing of wood refuse has engaged the attention of engineers for many years, and it has been the author's good fortune to have access to a plant for experimental purposes and the collection of data. This has enabled him to design a new plant which, although not entirely trouble-free, places at his disposal information hitherto unobtainable, and which is now available for the correct design of wood refuse silos. The author considers that his best course, in order to make the paper as practical and helpful as possible, will be to describe the plant which he himself has designed and erected, giving the results of his experiments, calculations, and running tests, and concluding with criticisms and suggestions. The subject can be broadly divided into three parts, as can be seen from Fig. 1; these are (1) Collection and delivery; (2) Storage and feed; and (3) Steam raising. Less knowledge is available under the second of these headings than under the others, and in view of the fact that problems of dust removal are well known, the author does not propose to do more than give a general description of that side of the work, but rather to include a more detailed account of storage and feed.
Mechanization of Foundries
Authors: Beech A. S.
Published: October 2007

The paper describes the principal operations in mechanical moulding plants and makes special reference to the various types of machines for different classes of work; the preparation, reconditioning, and transportation of sand, mould conveying, pouring, and knocking-out; and means for the return of the empty boxes to the moulding machines. The author gives information derived from his practical experience in connexion with mechanized foundry plant. He discusses in detail the respective merits of various methods of mechanical moulding, and contrasts the jolting method with ordinary “straight pressure” moulding. Under-sand frame ramming is also described. Reference is made to the improvements in working conditions which can be effected by mechanization and by proper ventilation at the knocking-out station. Finally, the author describes a number of examples of mechanized or semi-mechanized foundries, and shows how mechanization can be applied even to quite small plants.
Vibration in Power Station Steam Pipework
Authors: Cowlin F. J.
Published: October 2007

In recent years vibration in steam pipe lines in power stations has been of more frequent occurrence, causing in one or two cases a temporary limitation of the load-carrying capacity of the plant until the trouble could be either minimized or eliminated.

The present report summarizes the information collected by an exhaustive inquiry covering all the present available sources of information. It deals with the prevalence of the trouble, its nature and effects, arriving at the conclusion that it is in some way associated with the use of corrugated piping, which has been increasingly used as a result of the more stringent flexural requirements of modern pipe layouts.

The remedial measures so far employed are described; but these have been hampered by a lack of knowledge of the fundamental cause of the trouble and have been applied haphazardly.

The conclusion drawn from the inquiry is that a prima facie case exists for special research being undertaken, but that it is difficult to see how it could be carried out at the present time. Suggestions are made regarding the form which the research work might take; but in the meantime the report is published in the hope that the additional publicity may result in further information being obtained, which will assist in the solution of a complicated and difficult problem.
A Renaissance of Mechanical Properties
Authors: Vivian A. C.
Published: October 2007

The present technology of the mechanical properties of materials is suffering on account of its development from casual beginnings now known to have been ill-conceived and unsystematic. An improved understanding of the behaviour of metals under load is with growing difficulty reconciled with the original foundation and framework, and really calls for a replanning of the site and a redesigning of the edifice.

Starting afresh on the fundamental basis of the true stress-strain curve itself, the technology appears to lend itself to reconstruction affording major simplification and better illumination. The reorientation of outlook followed by planned action for systematization would appear to be justified and to promise progress in unexpected directions.
Problems Connected with Reclamation of Worn Parts by the Metal-spraying Process
Authors: Ballard W. E.
Published: October 2007

In times of peace the salvaging of worn parts is not usually a major problem confronting the mechanical engineer. Every consideration is given to new materials and to novel designs, but except for those engaged on works maintenance, the returning of old parts to service has not in the past received enough attention from professional engineers. In war time, however, the repair of damaged material becomes a national duty.

Although metal spraying by the wire process has become more widely known during the past two decades, the number of engineers who would feel competent to judge its suitability for any repair is comparatively small. The object of the present paper is to describe certain matters of interest to engineers in connexion with this form of salvage. It is not proposed to give details of metal spraying tools or pistols, as descriptions of these may be consulted in the technical press (Rollason, Turner, and Budgen 1939).† For the same reason an account of the many parts normally repaired by this method (Ballard 1942; Ballard, Fairbairn, and Pilkington 1942) is omitted. Metal spraying is being used commercially to a very large and increasing extent for reclamation work. To assist engineers faced with the problem of repairing a worn part, the author has arranged the paper in the form of answers to the following questions: ( a) Is metal spraying a suitable method of reclamation? ( b) If so, how must the work be prepared for spraying? ( c) What method of spraying and which metal should be used? ( d) What finish is necessary?
The Repair of Worn or Over-machined Parts by Electrodeposition
Authors: Hothersall A. W.
Published: October 2007

Worn or over-machined parts may be restored to size by electrodeposition of nickel or chromium followed by machining or grinding to remove excess of deposit. The mechanical properties and the adhesion of these deposits are described with special reference to nickel. It is shown that strongly adherent nickel coatings can contribute appreciably to the tensile strength of the steel upon which they are deposited.

Electrodeposited coatings may reduce the fatigue strength of steel and their use on parts subject to high alternating stresses should be made with caution. General notes on the process are given for the guidance of users.
Inspection Efficiency
Authors: Edwards J. C. , Bennett W. A.
Published: October 2007

The purpose of the paper is to outline the numerous directions in which improvements can be sought in engineering inspection. It shows how direct improvements in efficiency can be effected by carefully planned methods of recording results, including the use of statistical quality control, by adopting the principles of time and motion study in the planning of flow of work through inspection, and in the design of gauging fixtures and the arrangement of gauges. The importance of correct personnel selection and organization is stressed, as is also the avoidance of duplication of inspection. The paper concludes by quoting figures showing the substantial reductions which have been achieved in the authors' company by a progressive application of the methods described over a period of several years.
The Application of Statistical Methods to the Control of Industrial Costs
Authors: Neal Norman R.
Published: October 2007

Quality control studies the variation from standard of tangible articles, whereas “cost control” studies the variation from standard of the workers' efficiency, and consequent variation in production cost. In essence, the system consists in setting standard times, and thus standard costs, for all jobs and for the elements making up the complete jobs. Percentage divergencies from those standards are recorded at regular intervals on charts, a separate chart being used for each class of work, both as regards time and cost.

Control lines, calculated from previous results over a period, upon the same mathematical principles as for quality control, are inserted on the charts. When a reading falls outside the control line, action must be taken to ascertain the cause. However, unlike quality control in which articles covered by abnormal readings can be scrapped, abnormal time or cost must still figure in the final examination of production cost. A sufficiently fine subdivision of the elements of a job will prevent an occasional abnormal reading on one portion from giving abnormal reading for the complete job.

The individual readings are combined to form a grand total chart; careful watching of the detail charts enables the grand total chart to be maintained in control and it is from the latter chart that the “cost index” (percentage divergence from standard of the cost of the complete product) is obtained, which enables the latest actual cost at a particular moment to be determined directly. A continuous check is thus kept on the production cost of all the principal details; any abnormal fluctuations of cost become quickly apparent, and can be readily traced back to their cause. Concurrently, a simple method is provided for obtaining the total actual cost of the complete product at any time.
Sampling Schemes for Qualitative Inspection
Authors: Swan A. W.
Published: October 2007

The paper opens with a description of the applications of “qualitative” inspection. Briefly, it is used where “quantitative” inspection, or inspection by direct measurement on a continuous scale, is impossible, as in the case of a destructive test or a visual inspection for blemishes, or as an economical alternative through limit gauges to “quantitative” inspection.

The industrial and theoretical factors affecting the choice of a sampling scheme for qualitative inspection are discussed, particularly producer's risk (the risk that good material may be rejected), and consumer's risk (the risk that bad material may be passed). It is pointed out that a sampling scheme can be devised to give an agreed maximum producer's and consumer's risk. It is shown that the maximum allowable percentage of defectives cannot be set in an arbitrary manner, but only after consideration of the process average percentage of defectives. If the ratio of the maximum allowable to the process average is too low (e.g. if the requirement is too severe), the minimum sample size for reasonable producer's and consumer's risk is impossibly high.

A simple chart is provided, from which, with the industrial factors limiting the size of lots and the size of samples, the desired percentage of inspection, and the process average percentage of defectives as the “known” quantities, it is possible to read off the best single or double sampling scheme to give agreed maximum producer's and consumer's risks. The chart gives the best size of sample and the corresponding “pass up to” number of defectives per sample.

The paper concludes with instructions on when and how to change to more severe sampling conditions, when results from successive samples show a deterioration in quality from the process average; and discusses the need to keep the new conditions in force until there is satisfactory evidence that the quality has improved again to the process average.
The Fencing of Dangerous Parts of Machinery
Authors: Hepburn Henry A.
Published: October 2007

The Factories Act, 1937, introduced higher standards of general “fencing” or safeguarding requirements for machinery, and gave legal recognition to types of guards other than those of the fixed type.

During the past forty years, more attention has been devoted by machinery designers to the incorporation of guards to dangerous parts, but it is considered that more could be done in the future. Safety engineering is advancing in experience and practice, and is receiving an impetus by the appointment of safety officers and safety committees by many important firms.

In order to assist all concerned to an appreciation of those parts of machinery that the experience of the Factory Department for over 100 years has proved to be dangerous, certain axioms, applicable to various parts, or combinations of parts, of dangerous machinery are formulated, together with some principles of fencing. The object is to place in the hands of those who design machinery, or who have the responsibility of accident prevention in a factory, some guiding principles for application to their problems.

The principles of fencing are exemplified by illustrations of a few representative types of guards in present use, but such references are necessarily brief and are of but a few applications of the general principles. The requirements of the Act are in general terms, and compliance can be given in many ways, for which the paper is intended to give general guidance.
The Application of Fabricated Construction to Machine Design
Authors: Koenigsberger F.
Published: October 2007

Modern welding equipment and practice have given the machine designer the opportunity of applying fabricated welded construction in an efficient manner. This does not mean that steel fabrications should replace castings everywhere, but that steel should be kept in mind as a material which is available if technical or economic considerations favour its use as an alternative to that of cast iron. The designer of a fabricated steel machine structure has to consider the properties of the material and the problems of the manufacturing process, which are different from those which apply for the generally used cast iron construction. Layout arrangement, and shape of the fabricated construction have to be designed in accordance with the foregoing conditions.

In machine structures, stiffness against distortion and freedom from vibrations are usually of major importance as compared with strength. A comparison of strength, stiffness, and freedom from resonance for simple fabricated steel and cast iron structures is given in the form of graphs. The problem of the design of ribs for static and shock load conditions is discussed; and some designs criteria are determined. Some observations on the procedure of stress relieving after fabrication are also included.

The author, in addition to setting out the principles governing the design of fabricated structures, gives information on the execution of production drawings, including definite instructions for the most efficient procedure in the fabricating shop. Typical examples of fabricated machine structures are also included.
Condensing Locomotives
Authors: Lomonossoff G. V. , Lomonossoff G.
Published: October 2007

The paper deals with modern condensing locomotives both of the reciprocating and turbine types. The authors emphasize that such locomotives have recently been built in order to attain one of two mutually incompatible objects, namely, either the achievement of a very high efficiency in temperate climates, or the building of locomotives which lose no water for hot, waterless countries. The first object is best attained by use of a turbine with high vacuum, while the second is most readily achieved with a reciprocating engine having no vacuum at all. The latter has the advantage over Diesel locomotives in that any kind of fuel can be used.
Coupled Engine Torsional and Propeller Flexural Vibrations
Authors: Morris J.
Published: October 2007

In the initial treatment of resonant torsional vibration in engine crankshaft propeller systems, the basic assumption was made that for practical purposes a propeller could be regarded as a rigid pulley in the plane of rotation.

At an early stage, however, it became evident that theoretical results ensuing from the rigid pulley hypothesis could not explain certain engine-propeller failures, and thus it came to be realized that the flexibility of the propeller blades must have an important influence in coupled crankshaft-propeller vibrations.

In this paper an analytical method is given for the determination of coupled engine torsional and propeller flexural vibrations, in which account is taken of blade section, blade twist, hub moment of inertia, pitch setting angle, and speed of rotation.

The propeller blade is divided chordwise into six portions which are regarded as having their masses concentrated at their centres of gravity, while account is taken, so far as is possible, of the actual elastic properties of the blade. In the case of an aircraft propeller, the problem is simplified in that the mass axis is practically straight and coincident with the flexural axis, so that flexural and torsional vibrations of the blade itself are not coupled.

The theory has been applied to a three-blade propeller used on two different engines, in both of which agreement between the calculated critical speeds and those observed experimentally on the cable hangar was found to be satisfactory.

Moreover, the calculated fixed root frequencies for the fundamental and six overtones accorded very closely with the corresponding values evidenced on a -model of the blade by bowing and calibrated oscillator tests.
An Investigation into the Laws of Flow of Fluids through Beds of Granular Materials
Authors: Rose H. E.
Published: October 2007

A general equation governing the flow of liquids through a bed of granular material is derived by the use of the method of dimensional analysis. The equation so obtained has been verified by experiment for liquids having absolute viscosities ranging from approximately 16·0 poises to about 0·01 poise, the bed material being spherical shot closely graded about a mean size. Examination of the experimental results shows that the curve relating fluid resistance to Reynolds number has a form very similar to that for a single sphere moving in an infinite fluid, although the discontinuities which are present in the latter curve at the critical value of the Reynolds number are absent in the former; that the effects of the walls of the container are negligible; that the resistance to flow is accurately proportional to depth of bed, and that the hydraulic resistance varies inversely as the fourth power of the voidage of the bed approximately, for beds of normal density of packing, although the value of the index varies with the value of the voidage. The evidence also indicates that the hydraulic resistance is not accurately defined by the mean value of the voidage, but is subject to considerable variations due to the statistical nature of a bed, and that the effect of the walls of the container may be computed on the assumption of flow through a pair of parallel channels of different hydraulic resistance.
The Variable-Speed Hydraulic Governor
Authors: Bujak J. Z.
Published: October 2007

Due to the “square” law of the variation of centrifugal force with speed, a centrifugal governor is not well suited to variable-speed engines with a wide range of speeds. It lacks power at low speeds, which results in poor idling, and it has an excess of power at high speeds. Also the presence of heavy weights and springs may give rise to undesirable resonance phenomena.

This paper deals with the development and gives the theory of a variable-speed hydraulic governor consisting of a positive displacement pump and of a pressure-operated plunger. Such an arrangement should be distinguished from a hydraulic relay as used in servo-governors.

The story of its development is told, starting from the simplest possible scheme. The various troubles experienced are reported, together with the way in which they were overcome, leading to the design of a production type hydraulic governor meant primarily for road transport compression-ignition engines.

A mathematical theory of the hydraulic governor is derived and the conditions for stable governing established, as well as the criteria for a definite convergency of the disturbances set up by a sudden change of engine load. The magnitude of the temporary increase of engine speed following a sudden throwing-off of its load is calculated.

The results of the mathematical analysis are discussed and illustrated by some numerical examples. These compare quite well with the results of experiments carried out on the engine. Some of the conclusions arrived at, and the formulae derived, are applicable to variable-speed governors of any type.

A hydraulic governor which was developed as a result of the research described underwent several hundreds of hours of bench testing, as well as many thousands of miles of road testing.
Dynamic Loading and Some Indications of its Effect on Internal Combustion Engines
Authors: Chapman E. C. W.
Published: October 2007

The paper shows that when forces are applied to a mass which is connected to another mass by a stressed member, the “stressing forces” (i.e. the forces which must be considered when stressing the connecting member) are not the applied forces, but are fluctuating forces comprising the applied forces modified by vibratory forces at the natural frequency of the system.

The relative intensity of these vibratory forces depends upon the rate of application of the applied forces, and the period for which they are sustained, compared with the natural periodic times of the system to which the forces are applied.

Formulae are given for assessing the “stressing” forces under different conditions of application of the applied forces, and a graphical method of obtaining “stressing” force curves corresponding to applied force curves is described.

The application of the theory to some of the forces occurring in internal combustion engines is illustrated by a series of curves.
On the Theory of Automatic Control: Regulator Equations
Authors: Kaufmann Paul G.
Published: October 2007

Different types of automatic regulators can formally be represented by differential equations between the deviation from normal of the controlled variable and the displacement of the power device of the regulator. The equations are derived for the “floating-and-proportional”, the “proportional-position”, the “floating”, and the “first and higher derivative” control, and the characteristics for drooping and non-drooping control are described. The paper shows that identical results may be obtained by self-contained regulators and by control equipment consisting of separate units which may comprise a regulator proper, a servo-motor, and sometimes also one or more impulse transformers. Such composite control equipment has the advantage of greater flexibility, as the same elements may be used in various arrangements producing entirely different control actions.

The regulator equations by themselves give no information on the ultimate behaviour of a regulator, if applied to a particular plant, as this depends just as much on the characteristics of the plant itself. Information regarding stability of control, maximum deviation, and period of oscillation can be obtained only by combining the regulator equation with the equation describing the plant to which the regulator is applied.
A Thermodynamic Theory of Circulation in Water-Tube Boilers
Authors: Silver R. S.
Published: October 2007

A thermodynamic evaluation is made of the work available for, and the resistance to circulation by, natural convection in a water-tube boiler. This leads to a theory of circulation which is independent of the usual type of hydraulic theory expressed in terms of density difference.

The theoretical circulation equation is first used for the direct estimation of examples of particular circuits. Estimates made by means of this are in good agreement with estimates made on existing hydraulic theories.

It is then shown that the present theory lends itself to a more general formulation, and the treatment is developed to elucidate the general physics of natural convection in water-tube boilers. The fundamental variables are certain characteristic non-dimensional groups. The system is shown to possess critical limits of stability and of circulating quantity. Expressions for these are derived, and the general type of performance is given in charts. The relation of operating pressure and rate of heating to these critical limits is discussed.

In the course of the development a definition of an ideal standard boiler is proposed which is suggested to be a useful conception.

By means of the present theory an adequate account of qualitative characteristics of boiler operation can be given. Its possible quantitative accuracy is then discussed. Some comparison with experimental results is given.

Appendix I shows that the theory is generally applicable to the convection of non-evaporating fluids in tubes as well as to the boiler circuit. Appendix II indicates the relevance of the theory to the question of forced circulation. In Appendix III the problem is treated by dimensional methods and the characteristic non-dimensional groups are confirmed. Another characteristic group is shown to apply when capillarity is included. This permits some discussion of the effects of discontinuity and of the requirements of scale models.