bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling the Bicoid gradient
Authors: Grimm Oliver , Coppey Mathieu , Wieschaus Eric
Published: June 2010

Morphogen gradients provide embryonic tissues with positional information by inducing target genes at different concentration thresholds and thus at different positions. The Bicoid morphogen gradient in Drosophila melanogaster embryos has recently been analysed quantitatively, yet how it forms remains a matter of controversy. Several biophysical models that rely on production, diffusion and degradation have been formulated to account for the observed dynamics of the Bicoid gradient, but no one model can account for all its characteristics. Here, we discuss how existing data on this gradient fit the various proposed models and what aspects of gradient formation these models fail to explain. We suggest that knowing a few additional parameters, such as the lifetime of Bicoid, would help to identify and develop better models of Bicoid gradient formation.
Tapetal cell fate, lineage and proliferation in the Arabidopsis anther
Authors: Feng Xiaoqi , Dickinson Hugh G.
Published: June 2010

The four microsporangia of the flowering plant anther develop from archesporial cells in the L2 of the primordium. Within each microsporangium, developing microsporocytes are surrounded by concentric monolayers of tapetal, middle layer and endothecial cells. How this intricate array of tissues, each containing relatively few cells, is established in an organ possessing no formal meristems is poorly understood. We describe here the pivotal role of the LRR receptor kinase EXCESS MICROSPOROCYTES 1 (EMS1) in forming the monolayer of tapetal nurse cells in Arabidopsis. Unusually for plants, tapetal cells are specified very early in development, and are subsequently stimulated to proliferate by a receptor-like kinase (RLK) complex that includes EMS1. Mutations in members of this EMS1 signalling complex and its putative ligand result in male-sterile plants in which tapetal initials fail to proliferate. Surprisingly, these cells continue to develop, isolated at the locular periphery. Mutant and wild-type microsporangia expand at similar rates and the ‘tapetal’ space at the periphery of mutant locules becomes occupied by microsporocytes. However, induction of late expression of EMS1 in the few tapetal initials in ems1 plants results in their proliferation to generate a functional tapetum, and this proliferation suppresses microsporocyte number. Our experiments also show that integrity of the tapetal monolayer is crucial for the maintenance of the polarity of divisions within it. This unexpected autonomy of the tapetal ‘lineage’ is discussed in the context of tissue development in complex plant organs, where constancy in size, shape and cell number is crucial.
Economy in Design
Authors: Drew H.
Published: June 2010

Editorial Note.—The following contribution comprises an informal talk given to the Luton Centre of the Institution on 13th June, 1944. It represents an interesting and logical approach to a subject which is often neglected or misunderstood, and as the author of the talk has no immediate opportunity of elaborating it into the form of a full-scale paper, the notes are presented herewith in “talk” form in the hope that they will prove of interest and value.
Some Design Aspects of Poppet-Valve Cylinder Heads for Spark-Ignition, Liquid-Cooled Engines
Authors: Swaine J.
Published: June 2010

This paper deals in the main with those aspects of design which affect thermal and volumetric efficiency, and the requirements of satisfactory cooling; its contentions are illustrated by criticism of the accepted forms of cylinder head. Brief reference is then made to some of the problems which are encountered in the use of high compression ratios.
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.
Post-war Public-service Vehicle Maintenance
Authors: Parkinson T. H.
Published: June 2010

After outlining public-service vehicle maintenance schemes prior to the 1939–45 war, the development of post-war chassis design and its effect on maintenance technique is reviewed. The trend of vehicle component failures during the pre-war and post-war periods suggests modifications in maintenance practice. General design trends relating to the public-service vehicle chassis in the near future are predicted.
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.
Automobiles on Alpine Passes
Authors: Troesch Max
Published: June 2010

The MS. of this paper was received at the Institution on 1st January 1954. For the report of the meeting in London, at which this paper was presented, see p. 112.
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.
Experimental Work on Exhaust Valve Life at Thornton Research Centre
Authors: Bedale P. W. , Graham R.
Published: June 2010

Experience gained during the development of a bench test for assessing exhaust valve life has shown that the operating conditions of the engine are important in deciding not only the absolute valve life, but also the relative effect of fuel and lubricant combinations. It is concluded that short cuts in the estimation of exhaust valve life can give misleading results. The preparation of the engine for test and the test procedure are described, together with some details of the equipment used to observe the movement of the exhaust valves of a running engine.

The stress gradient due to temperature variation across an exhaust valve head is estimated. The temperatures from which the estimate was made were obtained by measuring the hardness of a specially heat-treated valve after it had been in service. The shape of the temperature contours agreed with those found by others, and using published stress rupture data it was found that calculated valve life periods, based on the thermo mechanical stresses set up due to temperature variations, were of the same order as those found in practice
A Comparative Analysis of Various Methods of Engine Braking
Authors: Webb C. R. , Lavender J. G.
Published: June 2010

The braking effect afforded by the engine of a road vehicle is normally regarded as a valuable addition to the wheel brakes. The degree of braking effort of an internal-combustion engine working on the overrun depends largely on how breathing is restricted, both at induction and exhaust.

The paper clearly reveals the marked advantage of the compression-ignition engine compared with the conventional petrol engine so far as braking is concerned, largely on account of the difference in compression ratio. Out of the various methods of restricting the breathing, that of applying an ‘exhaust brake’ has a distinct advantage, particularly so in the case of a compression-ignition engine, where a resistance horsepower may be realized of about 85 per cent of the power output of the engine.

An analysis of cylinder and manifold indicator diagrams taken from a multi-cylinder compression-ignition engine, using an exhaust brake, shows the interaction of the cylinder conditions, giving an advantage when a common manifold is used.

It was concluded from the complete investigation that maximum braking effort is obtained with an exhaust brake operated with an unrestricted induction manifold. While the volume of air contained between the exhaust brake and the cylinders is required to be as small as possible, the interaction between the cylinders by using a common exhaust manifold increases the braking effect.
Transmission Wind-Up in Vehicles Having Several Driven Wheels
Authors: Steeds W. , Ellis J. R. , Thomson J. L.
Published: June 2010

By wind-up is meant the twist that occurs in the transmission of a vehicle having several driven wheels but which is not provided with sufficient differentials to ensure equal distribution of the driving torque between the wheels, and which is due to inequalities in the effective rolling radii of the wheels. The first part of the paper discusses the importance of the wind-up phenomena and describes some experiments made on a rig in which wind-up could be developed and the wind-up torque be measured. The results show clearly that wind-up quickly reaches a steady state and that during this phase the effective rolling radii of the wheels change until they become equal.

The second part of the paper describes some experiments, made on another rig, in which the effects of speed of rotation, radial load, inflation pressure, and torque transmitted on the effective rolling radius of a pneumatic tyre, could be determined.

A selection of the results obtained is given in a series of graphs. The most important result is the establishment of the fact that the effective rolling radius of a tyre is a function of the torque transmitted by it and that if this function is known then the wind-up torque can be calculated. The paper concludes with a summary of the results obtained and some suggestions for ameliorating the harmful effects of wind-up.
Gudgeon-Pin Location
Authors: Cross R. C.
Published: June 2010

The gudgeon-pin must be located relative to the piston so that it does not rub against or damage the cylinder. Many methods of location have been used but the circlip at each end of the pinhole in the piston and the pinch bolt on the connecting-rod small end are currently the two most popular designs.

Another design which has met with much favour in the past is the use of a pad firmly fixed in each end of the pin. These pads are of suitable design and material so that, when they touch the cylinder bore, no damage is done.

Some older designs included the fastening of the pin by a setscrew in the gudgeon-pin boss or by a washer on each end of the pin joined by a tie bolt. A pin can also be located by a piston ring on the centre line of the gudgeon-pin boss.

First of all considerations is reliability, as failure of the locating means can cause very expensive damage. Cost and ease of assembly, light weight and simplicity are of importance.

The pinch bolt is a sound design but is slightly heavier than the circlip location and the pinch bolt itself requires to be locked by tab washer or other means. Circlips must be correctly designed and made to prevent heat forming under working conditions.
An Approach to the Problem of Pressure Charging the Compression-Ignition Engine
Authors: Tryhorn D. W.
Published: June 2010

It is shown from curves illustrating the effect of pressure ratio on charge density for various compressor adiabatic efficiencies that the efficiency of the pressure-charging system has a great influence on engine output. The Roots blower has been the accepted component for pressure charging for many years, but because of its low efficiency attractive engine outputs have not been obtainable. It is also very noisy and not easy to drive, so its use has been unpopular.

To eliminate the shortcomings of the Roots machine the ‘Bicera’ compressor was designed, and the operation of this novel form of pressure charger is described. Test results are given which prove the performance to be superior to that of the Roots type, and when fitted to an engine showed that a pressure-charged four-cylinder engine can give the output of a six-cylinder, naturally aspirated engine, and can be as economical in fuel consumption.
General Introduction to a Programme of Dynamic Research
Authors: Milliken William F. , Whitcomb David W.
Published: June 2010

This paper is a general introduction to a series of progress reports on an experimental and analytical investigation of the fixed-control directional characteristics of automobiles, and those mechanical properties of tyres used in the analysis of car stability and control. The programme under consideration utilizes aeronautical and control-theory techniques in deriving and substantiating equations of motion for the automobile. In addition, a six-component tyre-testing machine for static and dynamic tests on flat-road surfaces is described, and tyre data for a wide range of slip and camber angles are presented.

In this initial paper an historical background of technological progress in automobile handling is given in a framework of vehicle handling in general, with particular reference to the science of aeroplane stability and control. This presentation enables a relative evaluation of automotive progress. The specific research objectives of the programme are then examined. A summary of dynamic concepts and methods is given in Appendix II.

The paper also summarizes the results from the overall research programme, and concludes that the work has led to a better physical understanding of automobile behaviour, as well as to a mathematical model suitable for computing the fixed-control automobile motions. Significant comparisons are made between tyre data obtained in the programme and simple tyre theory.
A Device for Measuring Mechanical Characteristics of Tyres on the Road
Authors: Close William , Muzzey Clifford L.
Published: June 2010

This paper describes a machine which measures the mechanical force and moment characteristics of pneumatic tyres moving over flat road surfaces.

Development of interest in tyre force measurements is briefly reviewed, and the unique relationship of the Air Force-Cornell tyre tester to other tyre force-measuring equipment is indicated. The design evolution is discussed and the final configuration of mechanical, hydraulic, pneumatic, and electrical components is described in detail.

The axle carrying the test tyre is supported at its ends by units which measure five forces. A sixth measurement, braking torque, is made simultaneously. These six measurements are used to compute total road reaction forces and moments, referred to any desired axes. The supporting mechanism permits the test tyre to be steered 30 deg. to either left or right, tilted (cambered) 30 deg. from the vertical to left or right, and vertically loaded with a force variable from zero to 3,000 lb. A braking torque of 13,000 in.-lb. can also be be applied.

Electrical resistance strain gauges sense the forces and produce time histories on a recording oscillograph. The entire equipment is mounted on a 2 1/2-ton 6-wheel truck which can attain speeds up to 60 m.p.h. while testing tyres.
Suspension of Internal-Combustion Engines in Vehicles
Authors: Horovitz M.
Published: June 2010

For a clear understanding of this problem a basic knowledge of theoretical aspects is essential. An analysis of the vibrating system is therefore given, together with the effects of out-of-balance and torque harmonics.

Following a description of some forms of mounting unit, the author deals with incidental vibrations which are often caused by the flexibility of the vehicle structure. The elimination of these vibrations has been a major problem in recent years. Besides some orthodox designs described in detail, reference is made to a three-cylinder in-line, a three-cylinder opposed-piston engine mounting arrangement and the steel spring mountings used by an Italian car manufacturer.

An appendix gives the formulae for calculating the various modes of vibrations and their frequencies. A further section shows the properties of two rubber sandwich mountings arranged in V-formation.
Corrosion Prevention in Automobile Bodies
Authors: Hoar T. P.
Published: June 2010

The prevention of corrosion in car bodies has reached a high degree of excellence, or still leaves much to be desired, according to the point of view adopted.

The organic finishing of the main part of car bodywork, utilizing heavy undercoats and durable top-coats on steel often prepared by phosphating, has reached a very satisfactory degree of excellence on flat or nearly flat surfaces. Difficulties still arise at edges, corners, crevices and re-entrants. These are discussed in relation to general principles of design and of testing.

The finishing of trim is in a more fluid condition. Nickel/chromium plating of steel, zinc-base alloys and brass has long been the general bright finish adopted. The relative advantages and disadvantages of such trim and that made from bright anodized aluminium and from stainless steel are discussed. Newer finishes such as electrodeposited nickel-tin alloy coatings are also considered.

Temporary corrosion prevention, such as can be applied to finished bodies for the period after manufacture but before service, is described.

The contribution to corrosion prevention that can and should be made by the user is outlined. Storage methods vary widely, but are a very important factor in the life of a car. Cleaning and polishing methods are discussed.

The general principles of corrosion testing appropriate to car bodies are considered, in the light of the very varied corrosive environments that are experienced in service.
Inspection of Vehicles for Road Worthiness, with Special Reference to Methods and Equipment
Authors: Grime G. , Lister R. D.
Published: June 2010

An important section of the Road Traffic Act 1956 makes provision for the compulsory periodic inspection of road vehicles. In this paper are discussed some of the considerations involved, with special reference to the need for inspection, the items to be inspected, and the frequency of inspection. Descriptions are given of apparatus for measuring braking and lighting performance and, although for steering there is no commercial equipment with which a rapid assessment of the effects of wear and deterioration can be made, an experimental arrangement is described.

Several other items which it is important to inspect can only be assessed in terms of individual judgement which may nevertheless give valuable results. The accuracy and consistency of an assessment made by means of test equipment is affected by variability due to uncontrolled factors and by the accuracy with which the various parts of the operation can be performed. The equipment has been examined from this standpoint and the results are given.

Some of the facts which have to be considered in arriving at standards and test procedures are indicated and discussed.
Status of Automotive Petrol Injection in the United States of America
Authors: Gay Errol J.
Published: June 2010

The author of this paper gives the present status of petrol injection in the United States of America and some of the problems which have been experienced in adopting the various systems to engines for passenger cars. Three vehicle manufacturers are currently offering petrol injection on option at extra cost. Not many systems have been sold, probably owing to the very high retail price of the various systems.

A de-emphasis on horsepower has tended to reduce interest in fuel injection. Several American systems are shown and briefly described. The problem of reducing the cost of a system is discussed in terms of volume per day. Engineers are finding it difficult to match the performance of the carburettor. It has become necessary to provide ancillary equipment to the petrol injector so that carburettor performance is equal in regard to cold starting, warm-up and acceleration. Some systems have shown problems of high temperature operation.

The author is of the opinion that there is a future for petrol injection. It may take three to five years before volume production is seen. Engines may have to be designed to take full advantage of petrol injection, with less emphasis being placed on power output and more emphasis on best fuel economy.
Influence of the Lubricating Oil on some Operating Problems of the Two-Stroke Gasoline Engine
Authors: Golothan D. W.
Published: June 2010

The small two-stroke gasoline engine has recently become very popular owing to improvements in design and performance, and because of its general cheapness and simplicity of construction. Most of these engines are lubricated by the ‘Petroil’ system, that is, the oil and gasoline are mixed together before they are put into the fuel tank. This system, together with the characteristic design features of the engine, leads to various problems, the commonest of which are sparking plug fouling, exhaust port blocking, piston seizure, bearing corrosion, and general piston deposits.

Various engine tests were used to study these problems, and it was found that their overall solution demanded conflicting properties of the lubricating oil. By a suitable compromise, however, it is possible to formulate an oil which gives satisfactory results in all aspects of performance.
The Agricultural Tractor: Its Function and Design
Authors: Foxwell W. J.
Published: June 2010

This outline of the basic principles of tractor design takes into account international requirements. Today many new features are built into tractors, both for general duties and for specialized use. Engines, transmissions, controls, steering and accessories are discussed in relation to modern requirements.
Improving the Design and Performance of Road Tank Vehicles for Oil Marketing
Authors: Austin J. E. , Brear N. H.
Published: June 2010

In this paper the authors have set out to show how changed concepts in the design and construction of bulk liquid carrying road vehicles can assist towards more efficient and economical transportation.

Avenues for increasing tank truck efficiency are outlined, and consideration is given to some of the factors involved. An indication is provided of the kind of savings that could accrue from achieving a higher load factor and better average speed over the road. Comparison of these savings suggests that improved load factor should be given the greater emphasis.

Possibilities for securing higher payload capacity and more effective vehicle layout by using newer materials and new techniques in construction are illustrated by reference to recent prototype vehicle development in the United Kingdom and Germany.

Some details are given of strain-gauging undertaken on the prototypes to prove the tank design and to ascertain the feasibility of further structural refinements and weight-saving in this assembly.

The need for a reorientation of thinking on chassis component weights as a further prerequisite for higher vehicle efficiency is emphasized, and future trends of development having component weight reduction as a major consideration are suggested.
The Skidding Behaviour of Motor Vehicles
Authors: Jones G.
Published: June 2010

The author considers problems of front- and rear-wheel skids and gives test results. The characteristics of vehicles with either front or rear wheel drive are discussed, and tyres and road surfaces are considered. It is concluded that for optimum stability during the processes of braking or cornering, a vehicle must have a low centre of gravity, an even distribution of braking and cornering forces and proportional weight on the driving wheels. Improvements in road surfaces are recommended.
Air Swirl in a Road-Vehicle Diesel Engine
Authors: Fitzgeorge D. , Allison J. L.
Published: June 2010

The paper relates to the influence of port and piston shape on the dynamics of the air induced by a four-stroke oil engine of the type used for propulsion of commercial and passenger-carrying road vehicles. Consideration is given to the induction and compression strokes.

A rig was constructed and used for the study of an existing design of port and for the development of new designs. The results of tests on the rig were used to estimate the performance of the various ports (on the basis of volumetric efficiency and swirl production) when used in an engine, as the rig tests did not directly supply this information.

The squish process was also investigated by calculation, and the effects of variations in piston crown design considered.
Dynamics of a Four Wheeled Vehicle and the Effects of Suspension Geometry
Authors: Sethna P. R.
Published: June 2010

An analysis of the dynamics of a four wheeled vehicle is made with a view to determining the design requirements that will eliminate sprung mass motions during acceleration, braking and on curves. No restriction is put on the values of the spring rates of the suspension system in this analysis and thus the results are valid for vehicles with very low suspension spring rates. The results of the analysis show that it is possible to eliminate sprung mass motions under these conditions:

(1) if the four wheels move in certain prescribed paths with respect to the sprung mass; (2) if the braking and acceleration forces are distributed between the front and rear wheels in a prescribed ratio; (3) if the sprung mass distribution is such that it makes a certain product of inertia of this mass zero.
Fourth Paper: Causes and Control of Automotive Emissions
Authors: Caplan John D.
Published: June 2010

The sources and composition of emissions from gasoline-engine vehicles are described, the causes are elucidated, and the importance of specific components of the emissions is discussed. Methods of reducing the emissions from the various sources are presented along with an evaluation of their respective merits and limitations. In addition, the need for additional research concerning the importance of specific emission components is explained. Finally, the Automobile Manufacturers Association's co-operative programme for vehicle emission control is discussed.