bluuebunny/crossref_metadata_2025_split huggingface dataset:
Piston Ring Movement during Blow-by in High-Speed Petrol Engines
Authors: de Dykes P. K. 
Published: June 2010

This paper deals with electrical recording of the axial and radial movement of a piston ring, relative to its groove, in a petrol engine running under conditions of heavy blow-by. The engine was delivering power and records were made at speeds up to 5,500 r.p.m. The records show that the excessive blow-by often experienced at high engine speeds is not due, as generally supposed, to a vibratory piston ring radial “flutter” of frequency associated with the natural frequency of the piston ring. The records show instead that, at high engine speeds, the piston rings collapse radially inwards some 25 deg. before the end of the compression stroke and remain steadily collapsed until some 60 deg. after the start of the firing stroke. It is this steady collapse which causes the heavy blow-by. An explanation, supported by experimental results, is given of this radial collapse of piston rings. A description is given of two designs of piston ring and groove which were evolved as a result of this investigation. These two designs have not yet been thoroughly tested, but preliminary trials are very promising and suggest that with such designs blow-by should not become excessive at any practicable engine speed.
The Influence of Valve Port Design on the Volumetric Efficiency of the Compression-Ignition Engine
Authors: Dicksee C B. 
Published: June 2010

In the paper the author discusses the cause of the loss of pressure in the induction system of an internal combustion engine, and also the essential difference between the breathing conditions of a carburetting engine and those of a compression-ignition engine, and the features which are peculiar to the latter. He gives particulars of some experiments on the influence of valve ports of different shapes upon the breathing of a given compression-ignition engine cylinder. The experiments cover the measurement of the pressure loss under a steady air flow as well as the effect upon the volumetric efficiency under actual operating conditions. The effect of a change in valve lift is discussed also. The results of the experiments show that the governing factor in volumetric efficiency is the velocity of the air at the actual valve opening, and that a Venturi form of port provides much needed room for the accommodation of the fuel injector, without any sacrifice in volumetric efficiency, by allowing a material reduction in diameter of the port at a short distance ahead of the valve opening. It does not, however, possess any other great advantage over a parallel port with an equal diameter of valve seat.
Internal Expanding Shoe Brakes for Road Vehicles
Authors: Waller I. M. 
Published: June 2010

The wealth of information already available on the subject of brakes is indicated by a prolific bibliography. There is little scope for new subject matter, the only novelty being in the approach to the problems. Emphasis is laid on the importance of discriminating between the characteristics of the linkage and of the brake units themselves, and the paper concentrates on the latter. Shoe characteristics are considered separately from those of the complete brake assembly, and a standard “three-to-one” shoe is evolved as a common basis on which to compare the different types of brake. Formulae are given for both shoe and brake factors and it is shown that, by using their reciprocals, the form of the equations becomes remarkably simple, and that, when thus plotted, the significant values are more easily read. The features considered most desirable in a brake are listed and a preference is shown for the two-leading-shoe brake using sliding shoes and hydraulic or pneumatic operation. Some outstanding problems, such as improved cooling of the brake path, are raised. Wear, squeal, and fade are discussed, further developments in automatic adjustment are indicated, and a plea is made for improved oil and grease retention for hubs and axles to prevent contamination of brake linings. Brake testing is considered from first principles, and a routine for road testing is suggested. It is recommended that the investigation of temperature effects be confined to the laboratory. The paper concludes with a reminder that it is not the characteristics of the lining as a whole, but those of the surface finishes prevailing at the moment, which are being observed, and that the basis of further progress is the study of surface phenomena and the search for better cooling.
The Use of Wire-resistance Strain-gauges in Automobile Engineering Research, with Particular Reference to the Measurement of Strain in Vehicle Structures
Authors: Bristow J. R. , Metcalf P. , Mills C. H. G. 
Published: June 2010

A brief description is first given of the properties and method of using wire-resistance strain-gauges, indicating their sphere of usefulness and limitations, and the factors affecting their accuracy and stability, such as method of application, temperature, and moisture. The determination of static strain, using a simple bridge and galvanometer method, is illustrated by reference to measurement of strain in public service vehicle road wheels due to inflation of the tyre and the axle load. Dynamic strain determination is discussed with reference to measurements made on the frame and superstructure of a double-deck public service vehicle under road conditions, and typical strain records are given. Portable four-channel dynamic-strain recording equipment developed at the Motor Industry Research Association (M.I.R.A.) especially for this type of work, and which is sufficiently free from microphonic signals generated by road shock, is described. This equipment consists of an A.C. polarized bridge, oscillator, amplifiers, and power supply, and recording is by photographing cathode-ray tubes.
The Development of the De Havilland Series of Engines for Light Aircraft
Authors: Brodie J. L. P. 
Published: June 2010

The paper deals with light aeroplane engine development over the last twenty-five years. During the whole of this period, the author has been responsibly engaged in design and development in this field and, naturally, the paper concentrates largely on designs within his direct experience, representative of the best light aeroplane engine practice. The author feels that no apology is needed for devoting a considerable proportion of the paper to the crankshaft, since progress in its design over a long period is sometimes a remarkably accurate indication of progress in general.
The Performance and Weight of Automobile Petrol Engines
Authors: Bastow Donald 
Published: June 2010

This paper gives the results of a general survey of the influence of various factors, such as valve arrangement, head design, octane number, and specific weight, on the power output of automobile engines. The scope of the paper is similar to that of the very early one presented to the Institution of Automobile Engineers (Lanchester 1907)†, but has benefited from the results of recent work. It was felt that many of the conclusions drawn from the survey could be presented most effectively by calculating, as a basis for comparison, the primary dimensions and performance characteristics of a series of engines, each intended to develop 100 b.h.p. The results are collated in tabular form.
Wear of Fuel Injection Equipment and Filtration of Fuel for Compression-ignition Engines
Authors: Austen A. E. W. , Goodridge B. E. 
Published: June 2010

The dependence of the wear of fuel injection equipment on abrasive-particle size has been determined using closely graded abrasive prepared by air elutriation. A mechanism of wear is proposed which accounts quantitatively for the wear observed. The particle transmission properties of filters in common use, and of possible alternative filter materials, have been measured using the same preparations of particles. Some information on the nature and particle sizes of solids in fuels is presented. Estimates of the effect of various filters in reducing abrasive wear are made for a particular particle-size distribution of abrasive. These estimates are compared with the results of a review of service experience with current filters, gauze, cloth, and felt, in Great Britain. The choking properties of filter materials have been compared using a waxy sludge obtained from marine Diesel fuel, and a hypothesis of the choking mechanism is proposed which makes it possible to predict choking behaviour from initial resistance and thickness, and to assess, by means of a “figure of merit”, filter materials of different particle-transmission properties and thicknesses. For some services improved filtration is necessary. Papers transmit fewer particles than cloth or felt but choke more readily, necessitating the use of a large filter area; but provided the paper and free volumes on the clean and dirty sides are suitably chosen, a paper filter appears to be practicable giving a greatly improved pump element life with adequate filter element life and reasonable bulk.
Noise in Private Cars
Authors: Bristow J. R. 
Published: June 2010

The reasons for making objective analyses of the noise in vehicles, how such analyses are carried out, and their subjective interpretation are discussed. Results of the objective comparison, by octave-band analysis, of the “noisiness” of three vehicles are given and critically discussed with reference to the subjective “noisiness” of the three cars. Wind noise in two cars is also briefly referred to. It is suggested that detailed objective octave-band analyses of the type outlined, carried out over a speed range are capable of correct subjective interpretation and define adequately, and permanently, the “noisiness” of a vehicle.
Recent Developments in “Knock” Research
Authors: Downs D. , Wheeler R. W. 
Published: June 2010

Although the importance of “knock” in limiting the power output and efficiency of the spark-ignition engine was realized long ago, and much empirical information has been accumulated which has enabled engine design and fuel quality to be improved—so minimizing the restrictions due to knock—progress in understanding the fundamental nature of the knocking process has been comparatively slow. Recent work, both in Great Britain and America, has improved our knowledge of the chemical and physical factors involved, resulting in a better understanding of the phenomenon. The use of an electromagnetically operated gas sampling valve has enabled the sequence of chemical reactions, occurring in the engine cylinder, prior to knock, to be followed. Organic peroxides have been shown to be some of the most important intermediate products of combustion, and the effect of changing engine conditions—such as compression ratio, speed, and mixture strength—on their formation has been explored. These experiments have shown that there are at least two types of precombustion knock mechanism, one a “low”-temperature two-stage process involving the formation of peroxides, and the other, a “high”-temperature process which is non-peroxidic in character. Studies of the combustion reactions in a motored engine have confirmed these conclusions. So far as the knocking process itself is concerned, there have been two main schools of thought, one that it was an autoignition (i.e., spontaneous ignition) pure and simple and the other that it was a detonation wave perhaps preceded by autoignition. In reviewing published work, the authors consider that the bulk of the evidence favours the autoignition theory. An alternative explanation of the N.A.C.A. high-speed photographic work is put forward which would appear to support the conception of a two-stage autoignition.
The Significance of Laboratory Octane Numbers in Relation to Road Anti-knock Performance
Authors: Eatwell H. J. , Withers J. G. 
Published: June 2010

Fuel composition plays a prominent part in deciding the compression ratio to be adopted for an engine, since composition directly affects the knocking tendencies of motor fuels, and knock in turn imposes a limitation on engine performance. The engine conditions which affect knock are discussed and the fact that all fuels do not react equally to these conditions is dealt with in some detail. Laboratory and road knock rating methods are described, and results of tests on a number of fuels and cars, both in Great Britain and in the United States of America are used to demonstrate a relationship between laboratory and road antiknock ratings. It is shown that the road anti-knock performance of fuels is directly affected by their “sensitivity”, to a greater or lesser degree depending on engine “severity”. Severe engines are at a disadvantage in not being able to make full use of the high Research Method Ratings of sensitive fuels, and the factors in engine design and operation which cause high severity are discussed. It is emphasized how necessary it is to produce designs of engines of lower “severity”.
Engineering Changes
Authors: Drew Harold 
Published: June 2010

The handling of engineering changes by large and complex manufacturing organizations has become a function of major importance. The need for and the nature of engineering changes are not always appreciated. To some, every change appears as an unwarrantable obstruction to the smooth flow of production, and some believe that changes are demanded solely to correct the mistakes of an incompetent engineering organization. The paper seeks to show that all progress calls for changes and that the success of any undertaking will depend on its ability to effect changes promptly with the minimum of friction and dislocation. The concept that the devising and implementation of an engineering change is a combined operation is developed. Those concerned include not only the design engineers, but also production engineering, factory, supply, material control, inspection, and many others. Aspects considered in the paper include: the fallacy of the “frozen design”, the reasons for engineering changes, the paramount need to avoid jeopardizing the continuity of production, the importance of proving the effectiveness of a change prior to its release, the need to consult departments affected by a change, planning and timing changes, the fallacy of batching changes, the costing of changes and the allocation of the costs, engineering change warnings, and interchangeability. The MS. of this paper was received at the Institution on 7th April 1952. For the Minutes of the meeting in London, on 10th March 1953, at which this paper was presented, see p. 90.
The Effect of Gradient on Fuel Consumption and Speed of a Road Vehicle
Authors: Webb C. R. 
Published: June 2010

There is a considerable need for a reliable means of determining the effect of gradient on fuel consumption and journey time of road vehicles. In order to decide whether a proposed road improvement, involving the elimination of steep gradients, is to be an economical proposition, some reliable estimate is necessary of fuel and time likely to be saved as a result. The approach used in the paper is of general application, and depends on equating the engine output to the resistance to motion under uniform speed conditions. It is concluded that, for a light vehicle, a nearly level surface is best from the economy point of view. Fuel consumption for a journey between two points at the same altitude, on roads sloping at one in four, is nearly three times that for the same journey on the level. At the same time, the journey takes over three times as long. The paper also reveals the inherent inefficiency of the spark-ignition engine used, as it is for the majority of journey times, at part-throttle operation. Arguments are made for wider gear ratios and improved engine characteristics on private cars. The MS. of this paper was first received at the Institution on 8th November 1951, and in its present form, as accepted by the Council for publication, on 8th March 1952.
Problems in the Design and Development of an Economical Automobile Gear-box
Authors: Stott T. C. 
Published: June 2010

The demand for still greater reductions in weight together with the general stepping-up of vehicle performance with larger power units has placed upon the transmission engineer the onus of producing a small, lightweight and compact design yet capable of giving a satisfactory life. Economy in both weight and cost has become a primary requirement, and if this is to be met, a close study must be made of all the detailed components in order that the utmost can be obtained from each pound of material used. The maximum possible life of spur and helical gears is seldom achieved, as premature tooth failure occurs through poor face comformity of the mating teeth. The causes and effects of such nonconformities, whether dimensional or resulting after heat treatment, are dealt with, and the measures that can be adopted for their correction discussed. The elimination of any tendency to corner loading and, to a finer degree, the crown shaving of the teeth enable higher basic stresses to be adopted with corresponding smaller and more economical gear trains. Investigations into syncromesh mechanisms have indicated that synchronizing efficiency depends largely on attention to certain small details. An appreciation of these points will permit of quite small diameter synchronizers functioning satisfactorily without their useful life being in any way impaired by the higher loadings involved. Syncromesh problems are treated generally with particular detailed reference to design for high performance. It is unfortunate but nevertheless axiomatic that the tendency to self-disengagement of the gears increases as the loadings and stresses of the components are increased, and no paper on the design of an efficient economical transmission could be complete without its mention. The general causes of self-disengagement are discussed together with design features which can be embodied for its avoidance. The problems generally associated with the gear train which present definite requirements, of the casing, shafts, selector mechanism, etc., are dealt with. In conclusion, descriptions of the test equipment and tests used in the development of high-duty transmissions are given. The MS. of this paper was received at the Institution on 5th February 1953. For the Report of the meeting in London, at which this paper was presented, see p. 27.
Functions of Materials in Bearing Operation
Authors: Love P. P. , Forrester P. G. , Burke A. E. 
Published: June 2010

In this paper, the numerous factors affecting the operation of plain bearings, principally crankshaft, main, and pin bearings, are considered, and the problems of bearing design, from the aspect of selection of the various materials which are combined in the construction of a bearing assembly, are discussed. An attempt is made to bring together conclusions reached by studying the factors referred to, and the performance of bearings in practice. The latter is based on a study in summary of the three kinds of bearing failure, namely, seizure, excessive wear, and mechanical breakdown. Comment on recent work by Lunn and by Roach is made, and a working hypothesis on the effective fatigue strength of a bearing lining is proposed. The MS. of this paper was received at the Institution on 6th October 1953. For the report of the meeting, on 8th December 1953, at which this paper was presented, see p. 145.
The Running-in of Engines: Choice of Cylinder Bore Finish
Authors: Williams K. R. , Daniel S. G. 
Published: June 2010

The process of mating of piston rings and cylinder bores in newly assembled Diesel and petrol engines is described, and it is shown that an optimum surface finish exists which leads to rapid running-in—or break-in as it is sometimes termed—when either straight mineral or additive type engine oils are used. In particular it is shown that the running-in of engines fitted with either cast-iron or chromium-plated piston rings may be of short duration when additive type engine lubricants are used in conjunction with a suitable bore finish. Rig and engine tests are described which demonstrate the influence of surface finish on both the wear and the consumption of oil which occur during the running-in process. It is suggested that there are two components of surface finish which affect the running-in process. One of these components, the surface undulations of short wavelength (surface roughness) influences the rate of wear during break-in, whilst the surface undulations of longer wavelength (surface waviness) determine the amount of wear which must occur before the running-in process is complete. Whatever surface finish is chosen for the cylinder bore, to achieve a break-in which is as rapid as possible it is desirable to eliminate those errors in the machining process which give rise to waviness.
Fuel Requirements of the Small High-speed Diesel Engine
Authors: Barrett G. M. , Freeston H. G. 
Published: June 2010

Small high-speed Diesel engines used in automobiles require a combustion cycle more near to the Otto than the Diesel, and this means a very short injection period. The authors discuss the problem of noise and make suggestions for its elimination. Extensive tests have led them to believe that a separate combustion chamber is the most suitable for this type of engine. The excellent economy at part load and the advantages over the gasoline engine are attributed to the high expansion ratio and the inverse relationship of load and thermal efficiency. Consideration is given to fuel requirements and results of tests are given. The distributor type fuel pump is considered to be better than the in-line jerk pump. Methods of eliminating vapour lock when using the more volatile fuels are suggested. Preliminary information suggests that the small Diesel will run considerably longer than the same size gasoline engine before it requires reboring or relinering. The authors conclude with recommendations for the ideal fuel.
Disk Brakes for Motor Vehicles
Authors: Bradbury F. J. , Parnell F. G. 
Published: June 2010

The development of disk brakes is reviewed from the early part of the twentieth century to the present time. A number of designs are discussed and the characteristics of disk brakes are compared with those of drum brakes. In particular it is shown that the outstanding feature of the disk brake is its anti-fade characteristic which gives it superiority over the drum brake in installations where space is restricted. The main part of the paper is devoted to a consideration of those factors which control design, and it is shown that rigidity is of paramount importance if a disk brake is to be used without an external servo. Methods of obtaining the required degree of stiffness are discussed and curves are drawn to show the influence of caliper stiffness and other lost motions on displacement ratio and brake pedal travel. The application of disk brakes to commercial vehicles is discussed and details are given of an installation on a passenger service vehicle. Consideration is also given to the hand operated disk brake on the transmission of commercial vehicles, and the paper outlines why this arrangement may become more general when disk brakes are used on the road wheels. Friction pad characteristics are discussed in relation to rate of wear and recommended horsepower absorptions. There are many problems associated with the installation and protection of disk brakes and these are outlined with emphasis on the need for attention to caliper position and wheel-bearing design. It is also suggested that although the exposed disk brake has given satisfactory results it may become necessary to shield the disk which would result in either poorer cooling or complex ducting.