bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual exposure to Simulium bites and intensity of Onchocerca volvulus infection
Authors: Jacobi C A , Enyong P , Renz A
Published: June 2010

Background

Onchocerca volvulus, the causative agent of river blindness, is transmitted through the black fly Simulium damnosum s.l., which breeds in turbulent river waters. To date, the number of flies attacking humans has only been determined by standard fly collectors near the river or the village. In our study, we counted the actual number of attacking and successfully feeding S. damnosum s.l. flies landing on individual villagers during their routine day-time activities in two villages of the Sudan-savannah and rainforest of Cameroon. We compared these numbers to the number of flies caught by a standard vector-collector, one positioned near the particular villager during his/her daily activity and the other sitting at the nearest Simulium breeding site.

Results

Using these data obtained by the two vector-collectors, we were able to calculate the Actual Index of Exposure (AIE). While the AIE in the savannah was on average 6,3%, it was 34% in the rainforest. The Effective Annual Transmission Potential (EATP) for individual villagers was about 20 fold higher in the rainforest compared to the savannah.

Conclusions

Here we show for the first time that it is possible to determine the EATP. Further studies with more subjects are needed in the future. These data are important for the development of future treatment strategies.
Alterations of dendritic cell subsets in the peripheral circulation of patients with cervical carcinoma
Authors: Ye Feng , Yu Yan , Hu Yuting , Lu Weiguo , Xie Xing
Published: June 2010

Patients with cervical carcinoma (CC) are frequently immunocompromised. Dendritic cells (DCs) are potent antigen-presenting cells. Using multicolor flow cytometry, the percentages of CD11c+ (DC1) and CD123+ (DC2) subsets, were determined in the peripheral blood of 37 patients with cervical carcinoma (CC), 54 patients with CIN, and 62 healthy individuals. A substantial reduction of circulating dendritic cells and accordingly immunodepression may be associated with increased IL-6 and TGF-β in serum. These findings could give expression to the immunosuppression of circulating dendritic cells in patients with CC and CIN, thus, may indicate novel aspects of cervical carcinoma immune evasion.
Report of the Automobile Research Committee on Contraction of Aluminium Alloy Bearings
Authors: Farkas L. , Ludicke H.
Published: June 2010

The nature and the causes of contraction of aluminium alloy bearings have been investigated. Previous test results indicated that contraction is due to plastic straining of the bearing material. This is confirmed by calculation of the stresses set up in the bearing alloy, which are caused by the interference fit between bearing and housing and the differential thermal expansion of aluminium alloy and steel.

The variables affecting bearing contraction are then considered under the headings:—( a) Strength of material; ( b) interference fit; ( c) bearing wall thickness; ( d) bearing size; ( e) connecting-rod wall thickness. Finally, the effect of temperature upon bearing clearance is considered.

The results show that contraction can be prevented by a suitable choice of the bearing material and control of the dimensions. In particular, the interference fit should be kept low, and an alloy should be used which has a relatively high elastic limit in compression.

The application of the results may be extended to light alloy bearings in general and for both bush type and split bearings fitted in steel housings.
Some Notes on the Design, Development, and Production of High-Speed Compression-Ignition Engines
Authors: Markland S. , Tattersall N.
Published: June 2010

The high-speed compression-ignition engine has now almost completely superseded the spark-ignition or petrol engine as the power unit for heavy goods-carrying commercial vehicles and public service buses and coaches.

The principal reasons for the popularity of this type of engine amongst users of commercial vehicles in general are, in the authors' opinion, due to: ( a) the high thermal efficiency attained, which results in the maximum number of miles per gallon of fuel consumed, and ( b) the high degree of mechanical reliability resulting in trouble-free operation for long periods.

The results that are being obtained to-day are the outcome of many years of careful and painstaking work in the designs office and the test laboratory, together with the practical experience gained in the operating field. Except during the war years, development work has proceeded steadily in this country since the late 1920's. No revolutionary changes have been made during this period, but combustion has been improved (resulting in higher thermal efficiencies), and the mechanical weaknesses of some of the earlier designs of engines have been eliminated.
Export Vehicle Design
Authors: Fulton H. W.
Published: June 2010

The author seeks to show that the change of outlook, occasioned by the demand that a far greater proportion of output be exported than in past years, calls for a special study of overseas market requirements.

The difficulties of meeting road transport regulations in other countries are explained, with respect to the vital need for achieving the maximum degree of standardization, and the obstacles to this imposed by home regulations are described.

A description of climatic and topographical conditions found abroad is included, and it is maintained that the designer should be given the opportunity of making contact with the operator, and of experiencing such operating conditions for himself. An outline questionnaire, covering the kind of information required before design is commenced, forms an appendix, some aspects of which are elaborated in the main text. The questionnaire comprises a section covering the general requirements for the particular territory, and a section covering specific requirements for a particular duty within that territory. Certain features in design that are readily acceptable in overseas markets are noted.

The paper is illustrated by some interesting photographs of the road conditions that have to be faced by vehicles in service.

After touching on the question of after-sales service, the author concludes by emphasizing the value of compromise in the design of export vehicles.

Many of the principles suggested in this paper are applicable to any export commodity, but the author's interpretation of them is naturally coloured by his experience with commercial trucks and buses.
The Theory of Gear-changing
Authors: M'Ewen Ewen
Published: June 2010

With certain simplifying assumptions, the validity of which is examined, the elementary differential equations relating synchronizing torque, time, and inertias are set up and solved. The effect of variation in the controllable variables is considered, and it is shown that the principal factor is the rotational inertia of the parts between the clutch and the synchronizer. The heat rating of synchronizers is discussed.

The effect of scale is next considered, and it is shown that it is absolutely more difficult to effect synchronous gear-changing on larger vehicles.

A coefficient of friction at the synchronizer varying linearly with slip speed is chosen as a first approximation to variable friction, and the corresponding differential equations are set up and solved. The crash gearbox without synchronizers is discussed.

Failure to effect a synchronous change by crashing through is considered for baulked synchronizers and the equations of equilibrium are obtained. Failure to effect a change due to loss of way from too slow a change is also examined.

The performance of the synchronizers of an automobile gearbox is calculated and the results obtained by the variable or constant friction methods are shown to be of the same order; both agree satisfactorily with test results. The predicted effectiveness of baulk also agrees with trial results. Similar calculations are made for the German Panther tank gearbox and the phenomenon of the unsatisfactory change from second to third gear proven on test is predicted.

Finally, the application of the foregoing methods to easy-change gearboxes other than synchromesh is mentioned.

The use of similar methods with main engine clutches is discussed in Appendix I.
Air Condition Control for Automobiles
Authors: Steadman C. S.
Published: June 2010

The author begins by explaining what is meant by “air condition control” as applied to vehicle interiors as distinct from “air conditioning”, and proceeds to outline the technical requirements to be met. The necessity for air condition control is assessed, and a review of past practice is followed by comments on current British and American car-heating systems. The factors involved in a practical system for automobiles, including screen and window clearance, are combined in a detailed performance specification for an average British 2-litre, five-seat saloon car, while, in addition, special climatic effects are considered. There are alternative sources and methods of heat and air supply, and a section is devoted to testing equipment both in the laboratory and on the road. The paper, which is concluded with a forecast of future trends of development, is supplemented by a tabulated survey of the systems employed in well-known automobile types and by a statement of the mathematical relationship between the design factors described earlier.
Liquid Methane as a Motor Fuel
Authors: Pearce M.
Published: June 2010

A comprehensive programme of work on the development of liquid methane as a motor fuel was started in 1938 in the Department of Chemical Engineering and Applied Chemistry, Imperial College. This paper describes some of the work concerned with the actual utilization on the vehicle. The factors affecting power output and fuel economy are discussed, and engine test results obtained at the laboratories of Messrs. Ricardo and Company, Engineers (1927), Ltd., are presented. Work on the development of a suitable vacuum-insulated fuel tank is described with particular reference to “neck losses”. The vehicle fuel system and its components as finally developed are described, and the results of long-distance service trials of a motor ‘bus with the normal and a higher compression ratio are given. A disadvantage of liquid methane with the fuel system used so far is the loss of fuel by evaporation; the paper ends with a description of fuel systems which enable this loss to be virtually eliminated.
Automobile Test Rigs
Authors: Dawtrey L. H.
Published: June 2010

The paper opens by describing the background of automobile rig testing, with the word “rig” defined as “a contrivance or makeshift with the means at one's disposal”.

A range of equipment is desirable so that rigs can, after use on one particular test, be reassembled to form some other device, after the fashion of a constructional toy.

It is made clear that no indoor test can replace the testing of vehicles on the road, or tractors on the farm, but useful and quickly obtained results can be acquired with certain problems. Such work can be useful supplementary aid to a development programme.

As the essence of the subject is variety and speed, it is felt necessary to give several illustrations to emphasize the simplicity and ingenuity required in rig construction and design. The use of photographs in lieu of engineering drawings as an aid to later reconstruction is mentioned. Test rigs illustrated include those for fatigue failure in suspension, frame, body, and transmission; impact failures; body and chassis weaving; tractor and car transmissions; valve port flow; roller bearing wear; and vehicle air resistance measurements. Sufficient technical data are given to show the scope and results of the tests.
Long-distance Diesel 'Buses on the European Continent
Authors: Steenman J. A.
Published: June 2010

In this paper the author deals with the special requirements for Diesel 'buses used for long-distance travel on the European continent. These 'buses travel over flat and mountainous countries, covering distances of between 300–400 miles per day at a regular speed of 50–60 m.p.h., while between 70 and 75 m.p.h. must be maintained on German Reichs-Autobahnen.

As they are regularly operated in the Alps they must have a high continuous output when working on long and steep gradients. The 'bus must be capable of climbing a gradient of approximately 20 per cent (1 in 5), and this necessitates a heavier transmission than is required in normal use. It is also essential that gear changing can be easily carried out. With steep gradients the normal braking system is not capable of doing all the work and it is therefore necessary to fit a special exhaust brake to the engine; details of this brake and the results obtained by fitting it are given. The influence of a throttle valve in the air intake is discussed.

Light steering and a small turning circle are important when descending steep gradients, and the high front axle load of approximately 5,000 kg. when descending necessitates special springs and tyres.
An Investigation of Heavy Duty Lubricating Oils by Electron Microscopy
Authors: Barwell F. T. , Grunberg L. , Scott D.
Published: June 2010

A number of unused and used heavy duty (H. D.) oils were investigated by the electron microscope. Plain oils containing no additives and an oil containing an anti-wear additive were also investigated. No support was found for the suggestion that unused oils containing H.D. detergent additives are colloidal suspensions, as the micrographs were perfectly clear and no particles were found to be present. Two types of particle were found to be present in used H.D. and plain oils. One type of particle was of the order of 0·05 micron (500A***) and tended to arrange itself in chain structures. The other type was very much larger up to several microns in diameter. The two types of particle may have different origins.

It is concluded that the electron microscope is unlikely to provide a very useful means for the inspection of unused H.D. oils and the authors express doubts regarding the validity of an explanation of their successful use based solely on their deflocculating or dispersant action.
Some Notes on Carburation and other Fuel System Problems
Authors: Fisher Charles H.
Published: June 2010

While both vertical down-draught and horizontal side-draught types of carburettor are produced in Great Britain, the majority of instruments manufactured are of the down-draught variety. There is a distinct trend in body style towards low bonnet-lines, and this has created a demand for shorter down-draught carburettors.

A considerable portion of the paper deals with carburettor icing. This has become a most troublesome factor in fuel system performance throughout recent years, during conditions of critical atmospheric temperature and humidity. Various palliatives are possible. At the other end of the temperature scale come vaporizing troubles, causing hot starting difficulties in summer; conditions which assist the one are usually detrimental to the other.

The need for every possible fuel economy has resulted in automatic economy systems being incorporated in most carburettors. By exploring the mixture range with loops the maximum economy of any particular engine can be determined. Too much attention is often given to some minor discrepancy in fuel flow between one carburettor and another, and not enough to the discrepancy between the fuel flow induced between one engine and another.

Automatic chokes provide a controversial subject for discussion and their advantages and disadvantages are evaluated. The author has had a very wide experience with this form of starting.

Petrol injection was once believed to be the panacea for all fuel system problems. Enough development has been carried out to indicate that while there are certain advantages to be obtained with some forms of petrol injection, it is likely to be too costly for employment on the medium and low priced mass production vehicle.
Exhaust Valve Life in Small Industrial Gasoline Engines
Authors: Downs D.
Published: June 2010

The small industrial gasoline engine of 1 to 10 h.p. presents difficulties in ensuring an adequate exhaust valve life, which are not present to the same extent with the automotive engine. Thus, these engines often operate under a continuous full-load duty which does not permit combustion chamber deposits to clear themselves as readily as does the fluctuating load of the vehicle engine. The fact that so many of the industrial engines are single-cylinder units means that one piece of deposit under an exhaust valve may bring the engine to a halt, whereas in the multi-cylinder vehicle engine, the unaffected cylinders would generally pull the engine round until the deposit had cleared itself. Consequently, when the operating conditions of the valve are made more severe by increasing the lead content of the fuel, the industrial engine is particularly vulnerable.

The investigation described in this paper was carried out on five assorted water-cooled and air-cooled engines to establish the minimum modifications necessary to enable them to run for 1,000 hours between top overhauls using M.T. 80 fuel containing a maximum of 3.6 cu. cm. tetraethyl lead per Imperial gal. (T.E.L./I.G.). In addition to being the Services fuel, M.T. 80 can be regarded for this purpose as representative of the most highly leaded gasoline likely to be marketed commercially in the immediately foreseeable future. Under standard conditions, the water-cooled engines failed in 210–270 hours' full-load operation, and the air-cooled engines in 65–80 hours, owing to sticking of the valve stem in its guide.

The tests and modifications are described in considerable detail. Although in general 1,000 hours' operation can be obtained on all these engines with comparatively simple modifications, premature failure was always liable to occur in a random manner, owing to deposits showering down into the cylinder. This situation would seem difficult to overcome by mechanical design alone. Some preliminary results of an approach from a chemical aspect, using additives in the fuel, and various additive and non-additive lubricants, are described.
The Use of Shot Peening to Reduce Weight
Authors: Berry W. R.
Published: June 2010

The object of this investigation was to explore the possibilities of utilizing the shot-peening process on laminated spring leaves from silico-manganese spring steel as a means of increasing the working stresses, and thus reducing weight without loss in fatigue life.

The first part of the investigation showed that so far as fatigue tests alone were concerned it should be possible to increase the working stresses and thus save weight. To do this, however, would involve the bump stress exceeding the primitive elastic limit of the material.

Investigation of the effect of scragging (prestressing) to the British Standards (B.S.) Test Deflexion of L2/900 t as at present adopted in manufacture showed that such scragging had practically no effect on the elastic limit, but that if the scrag deflexion was increased to approximately L2/400 t an increase in the apparent elastic limit of the order of 40 per cent of the primitive elastic limit could be obtained, and that such scragging also improved the fatigue life in both the plain and shot-peened conditions.

It is considered that with effective scragging and shot peening it is probable that very considerable savings in weight, of the order of at least 20–25 per cent, and under certain conditions even more may be obtainable, provided trouble does not arise due to superimposed stresses of starting and braking torques, and possible embrittlement due to effective scragging. This does not seem to the author to be particularly likely at a weight saving of 20–25 per cent, but can be settled only by service trials which he feels should now be undertaken.
Some Measurements of Brake Usage in a High-Speed Saloon Car
Authors: Carpenter N.
Published: June 2010

The paper describes equipment which has been developed to record the duties imposed upon automobile brakes in service under various normal conditions. The principal measurement required was the rate of energy dissipation at the brakes, and this was recorded, together with the drum speed and deceleration, on a roll-chart recorder. The principles involved in these measurements are discussed in some detail, together with an outline of the practical precautions necessary to preserve the accuracy of the readings. From the results it will be possible to develop improved testing cycles for the test machines used in the development of brake lining materials but, in addition, some points of fundamental interest have emerged from the investigation. The results quoted in the paper show that the energy dissipated at the brakes is directly related to the mean journey speed for a given journey when other factors are kept constant and that:

Energy dissipated at the brakes = (mean journey speed) n where n has a value of about 3.4 for the conditions encountered in this investigation.

The effect of mean journey speed is shown to be much greater than that of the other variables considered although it must, of course, be taken in conjunction with the characteristics of the road. Braking in hilly country is shown to be appreciably more severe than on corresponding roads through flat country.
The Riding Qualities of Wheeled Vehicles
Authors: Cox H. L.
Published: June 2010

A wheeled vehicle traversing an irregular road surface is subjected to forced vibration. This vibration is analysed into heaving, pitching, and rolling modes, and means are described to compute or simulate the response of the vehicle both to continuous excitation at definite frequencies, and to isolated obstacles affecting one wheel at a time.

It is shown that a simple model, comprising only rigid masses, linear springs, and velocity damping, suffices to represent the riding quality of the vehicle, and a procedure by which the model may be matched to the vehicle as closely as possible is described.

The theory is illustrated by computation of the impact loads imposed on the wheels of a six-wheeled lorry when surmounting artificial obstacles, allowance being made for the effects both of the wheels leaving the road, and of interaction between the four wheels in the rear truck. Good agreement with experimental records of wheel load is shown, and it is suggested that similar computation or simulation applied to passenger-carrying vehicles would prove of value in the improvement of riding quality.
Recent Developments and Modern Techniques in the Use of Gaskets
Authors: Herrington M. G.
Published: June 2010

The paper is concerned with a brief review of the history of the cylinder head gasket. It sets out some of the initial defects and the manner in which they are overcome. The author mentions some of the successive developments which have taken place in engine design and construction which have necessitated a reconsideration of gasket design. The various changes in gasket construction, including an analysis of the considerations governing the introduction of the corrugated-steel gasket are stated.

The problems which are continually being met in the industry in relation to gasket troubles are considered, both from a design and production standpoint. The paper concludes with a short comment on the approach to gasket design in the future.
The Design and Development of Small Radial-Flow Turbo-Chargers
Authors: Judson C. A. , Kellett E.
Published: June 2010

Turbo-chargers are already well established for Diesel engines of moderate and high outputs, and there is no reason why this should not also apply to Diesel engines of 100 h.p. and upwards. In the former case, axial-flow turbines are used, but these suffer from serious disadvantages in the smaller sizes, so that radial-flow turbo-chargers are more likely to be adopted.

The range of applications on the smaller Diesel engine is very extensive compared with its larger counterpart, and in particular, automotive engines will have a serious influence on the design and development of the small turbo-charger. Owing to the rapidly and widely varying load conditions, the component efficiency must be high, and the rotating assembly as light as possible to give rapid response times. This involves intensive development of turbine and compressor, and the use of shaft speeds of 40,000–50,000 r.p.m., which until recently would have been regarded as impracticable for service conditions where a life of several thousand hours must be accepted.

The automotive field is also highly competitive, and production quantities are large. Consequently, the design of the turbo-charger must be such that it can be made economically and in large numbers, and at the same time be as efficient as possible over a wide range of operational conditions. Although economic conditions may fix the minimum size of the turbo-charger, the limit does not yet appear to have been reached on an aerodynamic basis, and reasonably high component efficiencies are readily attainable with rotors of 4 inches diameter or less.

The onset of exhaust smoke in some automotive service applications will not only dictate the matching conditions for the turbo-charger, but may also necessitate some further development to prevent it being a limitation on the power output from a given installation.
Air Suspension for Road Vehicles
Authors: Sainsbury J. H.
Published: June 2010

This paper presents a résumé of the course of development of the air springs of the double-convoluted and rolling-lobe types. The theory of the air spring design is discussed and typical methods of installation are described. The present-day air springs are limited to a maximum pressure of 100 lb/in2 to cater for the maximum static load. There are no minimum pressure requirements for a double-convolution bellows, but in order to obtain good flexing life and maximum spring response the rolling-lobe type is generally limited to a minimum pressure of 40 lb/in2.

The ancillary equipment for an air suspension system is described, this consisting of compressor, storage tank and levelling valves.
Petrol Injection in Germany
Authors: Heinrich H. , Stoll H.
Published: June 2010

An account is given of the development of the petrol-injection system in Germany, a subdivision having been made according to piston aero-engine, two-stroke automobile engine and four-stroke automobile engine.

The increase in performance achieved in the piston aero-engine by the injection system is described. Experiments carried out during the past 10 years on the two-stroke engine have shown that the demands made on the injection equipment in regard to injection accuracy and working life can be met forthwith, but that the injection system makes demands on scavenging which differ from those of the carburettor. The attraction of petrol injection in the four-stroke automobile engine is represented chiefly by the gain in performance, the wider controllable speed range and the faultless acceleration over the entire speed range irrespective of the driving conditions.

As a rule, the authors' company supply for all these engines the fuel-injection systems known in connection with Diesel injection, making allowance for the slight variations called for and irrespective of whether direct injection or manifold injection is used. Manifold injection points to ways and means of effecting economy in the injection method (pump and nozzle).

The control problem is the most difficult problem in petrol injection, no matter whether direct injection or manifold injection is used, and it calls for intensive development. The success of petrol injection is decisively governed by a faultlessly functioning mixture control.
Transient Temperatures in Brake Drums and Linings
Authors: Newcomb T. P.
Published: June 2010

A solution is given to the problem of heat conduction in an infinite slab when one face is subjected to a thermal flux which decreases linearly with time, while at the other face there is no flow of heat. This solution can be used to determine the transient temperatures reached during braking with uniform deceleration. Typical curves showing the agreement between temperatures determined theoretically and experimentally at varying depths inside a brake lining during single brake applications are given.

The problem of repetitive braking at regular intervals is also discussed and a comparison of theoretical and experimental temperature measurements is made. The effect of a nonuniform pressure distributed circumferentially along the lining is also considered in an appendix.
Vehicle Headlamp Beam Control
Authors: Jones K. J.
Published: June 2010

The problem of obtaining reasonable night-time seeing conditions when meeting oncoming traffic demands the use of uniform meeting-beam intensities. Variations will exist, and can be tolerated provided they are not too great or too frequent. The sources of variation relevant to the problem have been examined and the necessary degree of control stated.

At present lamp-aiming errors swamp all other variations. If these aiming errors can be reduced considerable improvement will be possible with existing equipment: by following the trends in aiming accuracy the need for lower lamp production variations and even better control of voltage may be established.

The immediate objective is stated as an improvement in aiming followed by a movement towards a higher degree of control of aiming, lamp production and voltage variation.
Construction and Behaviour Characteristics of Tyres
Authors: French T.
Published: June 2010

Development of automobile tyres over the past few years has led to certain improved performance characteristics and also to a wider choice of tyre behaviour patterns than has earlier been the case. To obtain optimum required performance characteristics for a particular vehicle design, attention must be paid both to individual tyre parameters and their interaction with particular features relating to the vehicle. Examples are given.

The impact of new materials for making tyres and of constructional variations in the tyres is discussed in relation to improved tyre performance characteristics, including comfort, road adhesion, ease of control, high-speed running, tread pattern life, noise and tyre power consumption. Testing techniques which have assisted in assessment of some of these items are discussed, with illustrative results. The relative effects of mechanical and tyre variables are summarized.

Reference is made to future trends in requirements of automobile tyre behaviour and possible consequent changes in tyre construction and form.
Some Problems in the Design of Crawler Tractors
Authors: Little L. F.
Published: June 2010

Problems encountered in the design of crawler tractors used in the earthmoving industry are considered tinder two principal headings, those associated with performance and those which arise when attempting to improve life and reliability under arduous operating conditions.

The characteristics of soils, their ability to sustain weight and tractive effort and the influence of track proportions are discussed, and problems in the application of conventional soil-mechanics concepts to the prediction of vehicle performance are illustrated by the results of field experiments.

Of the factors affecting durability the most difficult to contend with is that of shock loads in the suspension and transmission resulting both from ground conditions and the high rotational inertia of the transmission train. A comparison of recorded loads under operating conditions with mechanical and hydraulic transmissions shows the advantage in favour of the latter type.

The effect of a high average load factor and generally unfavourable atmospheric conditions on engine life are examined with particular reference to cooling and filtration.

The importance of reducing operator fatigue is emphasized, and future trends of development having as their objective the reduction of stress in both man and machine are suggested.
Initiation and Some Controlling Parameters of Combustion in the Piston Engine
Authors: Clarke J. S.
Published: June 2010

This paper reviews some of the research in combustion phenomena which has taken place during the past two decades. It is shown that much of the research carried out on gas-turbine development is of fundamental value and can be applied to other internal-combustion engines.

The problem is discussed from the aspect of intake considerations, mixture formation, and ignition and then there is a detailed section on chemical kinetics. A table of the effect of heat loss and volumetric efficiency is given. The various sections are illustrated with the experimental results. It is concluded that the theoretical and practical approaches can be combined and that further quantitative study is required on heat loss and mixture processes.
Natural Ventilation of Buses
Authors: Culver R. , Hickin G. N. , Sag N.
Published: June 2010

This paper describes the utilization of the pressure and flow pattern existing around a vehicle when it is in motion.

Methods by which these flow patterns can be made visible are described and the results of visual observations are discussed. As a result of these observations most suitable air inlet and outlet positions are established and the results of airflow measurements indicate that a substantial increase in the volume of air entering the bus was achieved.

In conclusion a design philosophy leading to optimum conditions is explained.
Research into Brake Usage in Passenger Cars
Authors: Livsey A. E. , Prestidge A. F. , Woor D. F.
Published: June 2010

A study is made of the brake usage of a number of passenger cars with different drivers over four widely varying routes. The latter are representative of conditions under which brake usage is likely to be severe. For each of the road sections a relation is derived between brake usage and various characteristics of the cars studied during the investigation, with the object of gaining information to develop a brake and/or lining assessment test, the conditions of which would vary according to the performance of the car. It is concluded that suitable information is obtained for the purpose of formulating the test, and that the braking experienced during the investigation was the maximum likely to occur under fast, but safe, driving conditions.
Application of the Flash Temperature Concept to Cam and Tappet Wear Problems
Authors: Dyson A. , Naylor H.
Published: June 2010

In the lubrication of a modern automotive engine the cams and tappets are among the most sensitive parts and are expected to become more difficult to lubricate as engine speeds increase. This paper deals with the two types of cam and tappet distress that occur mainly at high engine speeds; scuffing and polishing (or burnishing).

The occurrence of these phenomena is believed to be controlled by the temperatures in the contact zone, and in order to treat these in a quantitative manner the flash temperature theory of Blok has been applied to cam and tappet systems. For this purpose, some preliminary measurements have been made of the coefficient of friction between cam and tappet.

The contact temperature reaches a maximum at three points in the valve operating cycle; at the cam nose and at the two points of zero tappet acceleration. The relative values of these maxima depend on the cam contour, spring forces, materials of construction, etc.

If the temperatures at these points are excessive, either scuffing or polishing is liable to occur.

A case of polishing wear is examined, and it is shown that most of the observed details may be explained on the flash temperature theory. It seems necessary to postulate that a steel surface with a low velocity relative to a rubbing contact will scuff if the contact temperatures are high enough, but that the surface will become more liable to fail by polishing wear as this relative velocity increases. This is related to some phenomena observed with steel spur gears.

The theory may also be used to evaluate the relative scuffing properties of different cam profiles, with certain limitations which are explained in the paper, the metallurgy being constant. Some indications as to the design of a cam profile to avoid scuffing are also given, but there is no experimental backing for these.
A Comparison of the Wear of Small Gasoline and Diesel Laboratory Engines
Authors: Pike W. C. , Newman P.
Published: June 2010

Differences in the top compression-ring wear characteristics of two single-cylinder engines are presented. Wear determinations were made using the radioactive tracer technique. It was found that a high-speed, 19/1 compression ratio (C.R.), indirect-injection diesel-engine displayed generally more severe wear than did a 5/1 C.R. gasoline engine and experiments made to investigate the observed differences are described. As part of these experiments the diesel engine was extensively modified to enable it to be run as a spark-ignition engine under comparable conditions to the gasoline engine.

Comparative wear data are given for the two engine types under various controlled running conditions. The main test variables were: load, cooling-jacket temperature, fuel type and fuel sulphur content.

Analysis and discussion of the results is based on general considerations of corrosive and abrasive conditions prevailing in the cylinders as influenced by the combustion process.
An Investigation into Factors Which Affect Piston- Ring Wear under Starting Conditions
Authors: Cree J. C. G. , Thiery J.
Published: June 2010

The results of engine tests which were made, using radioactive piston rings for the measurement of engine wear, to explore the causes of start-up wear are described and discussed in this paper. The results obtained using a standard test procedure were used as data to compare the effect of applying variables immediately before and during the shut-down period. These variables included motoring the engine and changing the crankcase oil before shut-down; purging the crankcase and combustion chamber with dry nitrogen immediately the engine came to rest; and maintaining a high coolant temperature during the shut-down period. The reductions in start-up wear attributable to the variables applied have been expressed as percentages of the start-up wear incurred under the standard tests.
Noise Analysis of a Vehicle Transfer Gearbox
Authors: Ehrenreich M. , Rubin M.
Published: June 2010

The dynamical properties of mechanical systems are investigated mostly by direct contact methods. Analysing the acoustical noise spectrum generated by a mechanical system under working conditions provides a vital piece of information about its performance, behaviour and defects. Three transfer gearbox assemblies of a command car were investigated.
Instrumentation Problems of Internal-Combustion Engine Development
Authors: Hempson J. G. G.
Published: June 2010

Some reasons for use of varied measurement techniques in internal-combustion engine development are given and the broad principles of transducers are discussed. It is emphasized that the treatment is based on the practice and experiences of one organization and does not claim to be a critical survey of all possible methods. Practical examples of pressure, movement, strain and vibration measuring systems are given with reasons for choice of the method used. Some experiences with strain gauges in special circumstances are mentioned. Normal temperature measurements are not discussed but certain particular cases, such as differential thermo-meters and probes for dynamic measurement, are mentioned. The many uses of scaling or counting equipment are outlined with some examples, such as accurate tachometry. The visual display units and photographic recording gear used to present the output from transducers are described, together with some mention of driver amplifiers and carrier systems which are also needed. The problems of time sweep generators and marker pulses are presented together with an outline of better solutions not yet achieved.

The final section mentions some responsibilities of the instrument section outside the scope of the paper and refers to general principles guiding the operation and staffing of such a section and its position as a service to the basic purposes of the organization as a whole.
The Influence of Tractor Service Conditions on the Quality of Fuels, Lubricants and Protective Materials
Authors: Bates E. S. , Strettell R. P.
Published: June 2010

Petroleum products used in tractors are divided into these groups: fuels; lubricants and greases; protective materials. These products have to suit machinery design, methods of farm operation, and climate. The arduous conditions have resulted in development of improved oil products, and details of original research are given.
Tractor Mounted Implements and Adaptations
Authors: Hockey W. S.
Published: June 2010

The modern tractor has been adapted for use as part of a mechanized farming system and many novel adaptations are now produced. These additional facilities have influenced basic tractor design and have made tractors a much more useful machine. Details of some tractor-mounted implements are given.
Integration of Heating, Ventilation and Refrigeration into Vehicle Design
Authors: Copley D. W.
Published: June 2010

Current trends in car heating and cooling are reviewed. The need is stressed for close co-operation between the vehicle and heater manufacturers, in order to arrive at the most economical heating system to satisfy technical requirements within limited space.

A standard of vehicle heating is suggested, and the heat quantities to achieve this indicated.

While experience to date in heating has been almost entirely confined to liquid-cooled engine systems, the possibility of alternative heat sources are considered.

To ensure consistently satisfactory distribution of heat and ventilation, the need for improved body-sealing, together with a built-in, suitably positioned air outlet, is discussed.

While present heating systems satisfactorily condition the temperature of the air within the vehicle at low ambient and up to around 55°F, at higher temperatures there is a need to introduce into the vehicle, at high level, a large volume of fresh unheated air, this at present being achieved by opening windows. Ducting this air from the existing plenum chamber is suggested as a more elegant solution in which filtration could be included.

Vehicle refrigeration is reviewed and a smaller and cheaper system of ‘spot cooling’ suggested, as an alternative to the American approach of full car cooling, for the volume production 1–1 1/2 litre British car.
Improving Temperature Control in Diesel Engine Vehicles
Authors: Bisiker J. G. , Benford J. L.
Published: June 2010

The fitment of thermostats to water-cooled engines indicates the need for temperature control, but a thermostat is limited in maintaining adequate temperatures in diesel engine vehicles under many operating conditions.

Inadequate temperatures result in high wear rates and other disadvantages of cool running are also discussed. Equipment designed to improve temperature control is described in Appendix II and graphs of engine temperatures are shown in the paper for road tanker operation.

The effectiveness and limitations of fan control and automatic radiator shutters are discussed and known advantages of improved engine wear, reduced fuel consumption and better cab heater performance are illustrated from service experience.
Mechanics of Off-the-Road Locomotion
Authors: Bekker M. G. , Bekker M. G.
Published: June 2010

Off-the-road locomotion has always been, an important part of technology and economics. Yet it has never been treated within a comprehensive theoretical approach. Space research, and in particular preparations for the exploration of the surface of the moon, have in a sense dramatized the issue. As the trial and error method is not applicable in the latter case, theoretical work and research in simulated lunar conditions have already started. New emphasis on off-road mobility on this planet, stressed from commercial and military viewpoints, has also contributed to the growing interest in this area.

Early work on the mechanics of off-the-road locomotion started in 1913 in Germany and in 1943 in England, and laid the first cornerstones for a theoretical approach. The solid foundation for the development of the mechanics of soil-vehicle relationship, however, was first established between 1944 and 1950 in Canada. On that foundation the first general outline of a theory which covers all the physical phenomena pertaining to terrain-vehicle systems was completed in the United States around 1960. The results of this work were the main theme of the First International Conference on the Mechanics of Terrain-Vehicle Systems held in Italy in 1961. The theory is based on the Coulombian criterion of soil failure which relates to thrust, and on semi-empirical moduli of sinkage which relate to the motion resistance. It constitutes a working tool for engineers and planners and offers a general methodology for the further development of mathematical equations needed in the prediction of vehicle performance and design parameters. The accuracy of such predictions so far achieved is encouraging, although much improvement is necessary.

These new methods enable the user and designer of motor vehicles to have a much better understanding of the relative merit of various types of locomotion in various environments. They have laid a foundation for the more rational planning of vehicle development and the evaluation of design trends, and the preliminary optimization of terrain-vehicle systems in randomly changing conditions due to climate and geography has been made possible.

Long range evaluation of future trends in off-the-road locomotion indicate that the so-called articulated vehicles, composed of a number of self-propelled units linked together by free steerable joints, in a manner similar to a railroad train, offer great promise. Future progress is seen in terrain measurement, in the analysis of terrain-vehicle relations from the viewpoints of performance and design, and in research aiming at the improvement of the present theories.
Contribution to the Study of Deterioration in Automobile Engine Cams and Tappets
Authors: Cazaud R. , Renout M. , Daubertes C.
Published: June 2010

During the last few years the cam-tappet problem has become very important because of the continuous increase in the maximum rotational speed of engines for the purpose of increasing power. This necessitates the overloading of the springs in order to offset the inertia effects of the distribution system as a whole; the result of this is to increase the specific pressures of the cam-tappet unit. As the present tendency is to make engines revolve at ever greater speed, it is to be expected that the problem of the behaviour of these components in service will be more and more difficult to solve.

There is no doubt that the ideal solution lies in decreasing the inertia forces by giving up the rocker system, and using the arrangement of the overhead camshaft acting directly on the valve stem.

For engines with the traditional system of valve action by rockers, the problem of the deterioration of cams and tappets has been studied by Simca on a specially designed testing machine. The laboratory tests thus made have been followed by tests carried out by the Shell Company on engines on the test bench. The present paper sums up the results obtained.
Second Paper: Catalytic Purification of Car Exhausts
Authors: De Rycke D.
Published: June 2010

So far no less than 150 chemical components have been isolated in car exhaust gases and may be grouped as follows: (1) Oxides of carbon; (2) Unburned fuel; (3) Oxides of nitrogen; (4) Oxides of sulphur; (5) Lower hydrocarbons.

Smog formation is a complex photochemical reaction, and this has been reproduced in the laboratory. The catalyst device attempts to complete combustion by initiating and maintaining a medium temperature zone which, with additional air but no more fuel, will convert hydrocarbons and carbon monoxide into carbon dioxide and water. The composition of petroleum must be considered in relation to other factors. Tests with cars have shown operating problems, and results are given in the paper. Research continues on this complex problem, and development of the catalyst is well advanced.