bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of Vehicles under Trans-Antarctic Conditions
Authors: Pratt D. L. 
Published: June 2010

A 2158-mile vehicle journey was made for the first time across the Antarctic Continent from the Weddell Sea to the Ross Sea in the summer of 1957-58. A historical review of Antarctic polar journeys using vehicles is made. The problem set is analysed, and an operational specification temperature of -60°F chosen with storage to -90°F, which met the field conditions adequately.Light vehicles were chosen and the reasons are stated. The meaning of performance in relation to the project is analysed and an investigation of the main factors affecting performance is made under the headings of:Terrain (Traction and friction). Engines (Startability; preheating; batteries). Lubrication. Materials.Antarctic performance is examined under the headings of:Climate. Terrain (Traction, friction and field recovery). Engines (Startability; preheating; batteries). Lubrication (Consumptions, effects and analysis of wear and carbon deposit). Materials (Field fractures). Human factor (Wind chill—effect on design).The performance of the vehicles under these headings is stated and discussed and conclusions drawn in most sections.It is finally concluded that long-range unsupported vehicle journeys are feasible within the heart of the Antarctic Continent during the summer season.
Influence of Atmospheric Pressure and Temperature upon the Performance of the Naturally Aspirated Four-Stroke C. I. Engine
Authors: Dicksee C. B. 
Published: June 2010

The compression-ignition (C. I.) engine differs from other types of internal-combustion (I. C.) engine in that the fuel supply is entirely independent from the air supply and, further, that at all times a large excess of air is present. It is to be expected therefore that although the weight of air received will be influenced by atmospheric changes, the effect of these changes will be much less than in the case of an engine in which the fuel supply is dependent upon the air flow. Basically the effect is a change in air utilization, that is, air/fuel ratio. This is not universally realized as is shown by the fact that, quite frequently, a formula developed for correcting petrol-engine test results for atmospheric changes is applied to C. I. engine figures. The experiments described were designed to show the absurdity of this procedure and, if possible, to provide information from which a method of correcting C. I. engine results could be derived. The first objective is very definitely achieved; for the second, it is shown that a change in air utilization has precisely the same effect upon the indicated horsepower no matter whether the change is caused by the fuel delivery being varied while the air supply remains the same or the fuel supply is kept constant and the air supply varied by a change in temperature or in pressure.
Some Investigations on Cold-Starting Phenomena in Diesel Engines
Authors: Austen A. E. W. , Lyn W.-T. 
Published: June 2010

In this paper are recorded the findings on the more fundamental aspects of cold-starting work carried out in the laboratory at Acton during the past three years. It deals with both the criteria of an ignition under cold-starting conditions and how these criteria may be met by some practical forms of starting aid. From available ignition delay data and measured compression temperature it has been possible to correlate, in order of magnitude, the variation of starting time with both cranking speed and ambient temperature. The increase in compression temperature and pressure during continuous cranking with fuelling is found to be due partly to sealing action of the injected fuel and partly to the increased compression ratio. The effect of the slow oxidation of the fuel carried over from the previous cycle has been investigated and found to be insignificant. From these basic considerations, the effects of engine design and operating variables on cold starting have been discussed. The principles and limitation of intake air heating as a starting aid (both by burner as well as by electrical heating), heater plug, and heating the injected fuel have been investigated. For the engine used, the lowering of minimum starting temperature is about 20°C (for a fixed cranking speed) when using a burner aid, while a further reduction of 2° to 3°C may be expected if electric heating is used. It is found that the main function of a heater plug is to provide a high-temperature ignition source rather than a heat source. The failure of the fuel heating system is due to excessive heat loss both before the fuel enters the chamber and to the chamber wall due to impingement when it enters the chamber.
Contribution to the Problem of Starting and Operating Diesel Vehicles at Low Temperatures
Authors: Brunner M. , Ruf H. 
Published: June 2010

Using systematic cold starting trials with diesel (and also gasoline) vehicles in a large cold room, means of extending the serviceability of Swiss Army vehicles down to temperatures of about -13°F (-25°C) were studied. The first requirement for a successful cold start is a sufficient cranking speed. After study of the relation between motor oil viscosity at low temperatures and cranking speed, the minimum speed limits for a successful cold start were determined. It was found that the design and working temperature of the battery also had a very great influence. In addition, special ‘cold-starting’ batteries, or conventional batteries protected from excessive cooling gave much higher cranking speeds than unprotected types. It is therefore possible to have successful starts either at lower temperatures or at the same temperature using an oil of higher viscosity, the latter giving better lubrication in the warmed-up engine. When the minimum cranking speed has been ascertained, the properties of the fuel necessary for trouble-free operation must be considered. For starting diesel engines at temperatures down to -13°F (-25°C) starting aids such as the injection of a volatile auxiliary fuel, or the use of heating plugs becomes indispensable. In this case, the ignition quality (cetane number) of the fuel, so long as it stays within commercial limits, is of less importance. The greatest difficulty arises with the separation of paraffin wax which clogs lines and filters. With the aid of a rig test, consisting of all the main parts of a Saurer fuel system, the filterability of different fuels was studied in some detail. It has been found that different fuels behave quite differently. If the wax separates in large crystals, for instance, the coarse pre-filters may sometimes clog at temperatures very little below the cloud point of the fuel. More frequently, finely divided wax separates out and the fine filter proved to be the more critical in which case clogging only occurred at temperatures well below the cloud point of the fuel. It therefore proves rather difficult to correlate the behaviour of a fuel in practice with any of the conventional laboratory yardsticks used to assess the cold properties of gas oils. It is also unlikely that a ‘single-point’ laboratory test can be devised that covers all practical cases. A certain relationship between the results of the rig-filterability-test on the one hand and cloud point, pour point, and ‘filterability’ (DIN 51770) on the other is undeniable. The use of additives to improve filter-clogging tendencies of diesel-gas oil was not very promising. The best method appeared to be dilution with kerosine.
Fuel-Injection System Calculations
Authors: Knight B. E. 
Published: June 2010

A simplified method of calculating injection system performance has been developed for the use of applications engineers. It is particularly relevant to the problem of avoiding secondary injection and dribble. The calculation of the complete behaviour of injection systems has been programmed for a digital computer. Agreement with experiment is satisfactory and confirms that all important factors have been taken into account. These factors are quoted and the methods used for dealing with compression waves in the pipes are described in detail. Viscous friction and voids in the fuel are taken into account. As an example of the use of the programme, an approach to the problem of stroke to stroke variations of delivery in one line is described. A longer term objective is the reduction of the time required to match injection equipment to engines by using this and other computer programmes instead of experimental methods, up to the final trial stage.
Calculations of the Effect of Rate of Heat Release on the Shape of Cylinder-Pressure Diagram and Cycle Efficiency
Authors: Lyn W.-T. 
Published: June 2010

In these papers the gas pressure, temperature and cycle efficiency are calculated for various assumed simple heat-release diagrams using a digital computer. It is concluded from these calculations that for a given heat-release period, the cycle efficiency is essentially a single valued function of peak pressure and is independent of the actual shape of the diagram. There is an optimum peak pressure beyond which no gain in efficiency can be expected. The rate of pressure rise, however, depends on the initial slope of the heat release diagram. It is therefore both desirable and possible to have a slow rate of pressure rise for the same peak pressure with only slight loss in efficiency. The effect of compression ratio and the period of heat release have also been investigated. The theoretical cycle is then compared with what is regarded as the practically attainable ideal cycle. Finally, the optimum peak pressure for a given compression ratio, or alternatively the optimum compression ratio for a given peak cylinder pressure is defined.
Relation between Fuel Injection and Heat Release in a Direct-Injection Engine and the Nature of the Combustion Processes
Authors: Austen A. E. W. , Lyn W.-T. 
Published: June 2010

Fuel injection and heat-release analysis for a direct-injection (D.I.) engine have been carried out over a wide range of load, speed, and injection timings using a digital computer. From these results emerge the broad principles governing the combustion in a D.I. engine. A model is proposed for relating quantitatively the rate of fuel injection to rate of heat release and hence cylinder-pressure diagram. It is found that the same law for correlation holds over wide range of load and speed and injection timing. The predicted cylinder-pressure diagram agrees reasonably well with the measured diagram over all test conditions, thus establishing the validity of at least the main features of the model. Whilst it is perhaps too optimistic as yet to predict i.m.e.p. (10 per cent error), the agreement in the rate of pressure rise (almost exact) and peak pressure (about 5 per cent error) is such that practical applications (for example, resulting noise) are already possible. Arising from the heat-release analysis and high-speed photography a consistent picture of the combustion processes in a diesel engine is presented. It is shown that in general, and particularly in the case of D.I. engines, the highest rate of burning occurs immediately after ignition and the flame is essentially premixed in nature with low luminosity. This period of high rate of heat release is, however, very short and is followed by the main period which is essentially diffusion in character with high luminosity and comparatively lower rate. The effect of combustion-chamber type on these processes are discussed and comparison is made with heat release in a petrol engine.
Relation between Form of Cylinder-Pressure Diagram and Noise in Diesel Engines
Authors: Priede T. 
Published: June 2010

This paper is a sequel to an earlier paper and carries this aspect of the investigation on from that stage. The frequency analysis of cylinder pressure has been shown to be a satisfactory criterion of the ‘noisiness’ of a cylinder-pressure diagram. In this paper the effect of the properties of the measuring equipment, such as band width, is considered so that the results may be interpreted quantitatively in terms of the pressure rises and hence the amount of combustion involved. The effect of operating variables on the frequency analysis is investigated. In some cases stroke-to-stroke variations are of importance and frequency analysis and emitted noise are compared in relation to background noise. Over a limited range, the effect of type of combustion chamber has been explored and some observations with petrol as the fuel are included.
Cylinder Pressure Variations in Petrol Engines
Authors: Soltau J. P. 
Published: June 2010

The paper deals with a detailed research programme which was carried out in an endeavour to find out the cause of the cylinder pressure fluctuations from cycle to cycle which occur in a petrol engine. Every working variable was altered in turn, and its effect on combustion observed on an electronic engine indicator. The development of the cylinder pressure over a large number of cycles was recorded at each setting with the aid of an oscillograph camera. For more detailed observations, the photographed traces were replotted on a volume scale and individual P-V diagrams were studied and in some cases drawn as log P-log V graphs. The experiment showed that the fluctuations in peak pressures and i.m.e.p. were caused by differences in the heat-release rate from cycle to cycle. All hydrocarbon fuels exhibit similar variations, but town gas with its more rapid burning produces steadier pressure development. The air/fuel ratio of the mixture is the main factor which influences the magnitude of the maximum pressure variations from cycle to cycle. The steadier mixture ratio is in the order of 13 and on either side of this the fluctuations increase rapidly, especially on the weak end. Using several simultaneous ignition sources, it is possible to decrease the individual flame front path and therefore increase the resulting combustion speed, which reduces the fluctuations.
Theoretical Studies in Braking
Authors: Chandler K. N. 
Published: June 2010

In Part I of this paper, after a simple description of the basic properties of a pneumatic tyre, a highly simplified vehicle consisting of a pneumatic-tyred wheel bearing a load is considered mathematically during braking and during the release of brakes. By inserting numerical estimates it is shown that, among other results, from 15 mile/h a wheel may lock within 18 ms. It is also shown that under perfectly uniform conditions the stopping distance is appreciably less when the brake-shoe torque is approximately equal to the moment of the maximum frictional force that is possible between the tyre and the road, than for both greater and lesser brake-shoe torques. In Part II of the paper a commercial device—the Maxaret—designed originally to release the brakes of an aeroplane before the wheels lock on landing and then later to reimpose the brakes is briefly described and the mathematical equations of its operation, both in itself and in application to a highly simplified road vehicle, are set up. A numerical investigation, making use of the results given in Part I of this paper, was executed and the results are given. These show in detail the mode of operation of the device. These highly simplified calculations suggest that in its present form a much longer braking distance will result from using the device than would be obtained with locked-wheel braking. This is in conflict with experimental results and may be due to both the simplifications that had to be made for the numerical work and some of the empirical data used. Some of the former could be avoided if an electronic computer were available. Further investigation is desirable and this should enable the device to be adjusted to give the shortest stopping distance consistent with the avoidance of locked wheels.
A Test Schedule for Passenger-Car Brakes
Authors: Livsey A. E. , Prestidge A. F. , Woor D. F. 
Published: June 2010

Various forms of brake-fade test are used in the motor industry, and it is suggested that a standardized test schedule is required, the latter being based on contemporary operating conditions. A study of brake usage of a number of passenger cars with different drivers operating over four selected routes had been carried out previously, and the results of this investigation are used to formulate two tests which it is proposed should replace the existing fade test. The proposed tests simulate as closely as possible maximum braking conditions recorded on the four routes, and the test specification for any particular car may be arrived at by substituting known car characteristics into formulae. A test schedule is derived for a typical modern car, and the results obtained from the tests on this car are presented and interpreted.
Brake Usage in a Heavy Vehicle
Authors: Frood A. D. M. , Mackenzie D. K. , Newcomb T. P. 
Published: June 2010

This paper summarizes measurements made of the duties imposed on the brakes of a heavy vehicle when driven over a continental route which included the Susten and other passes in Switzerland and in Austria. On the Susten Pass an investigation was made of the effect of driving in various gears. The following data were determined for each brake application: vehicle deceleration, rate of energy dissipation and total energy dissipated at the brakes, the energy lost by drag losses, the energy absorbed by engine braking, and the temperatures attained in all drums and linings. Measurements were also made of the amount of energy imparted to the vehicle when it was accelerated by the engine between brake applications. Analysis of the results shows that a heavy vehicle travels at a fairly uniform speed down the mountain passes and consequently only a small percentage of the total energy dissipated is given to the vehicle by the engine in between braking. The work done at the brakes varied between 15 and 62 per cent of the total energy dissipated, the proportion depending on the steepness of the gradient and the driver's choice of gear for the descent. The maximum amount of work done at the brakes (5·66 times 107 ft.lb) was on the Susten Pass when the vehicle was driven in third gear. During such a journey the drums attained an average temperature varying between 350–400°C while the linings reached an average temperature in the range 275–350°C. A theoretical analysis is outlined which permits calculation of the temperatures attained at any stage of the descent. This analysis requires a knowledge of the work done in each brake application, together with cooling rates, and gives results in good agreement with the observed temperatures on the Susten Pass. Little difference was observed between the driving behaviour of the two drivers on the various passes; one driver made more brake applications per mile than the other but the duration of each application was less. Consequently, both applied their brakes for approximately the same total time and dissipated similar amounts of energy at the brakes when both used the same gear over the same descents.
Crossed Helical Gears for High Speed Automotive Applications: Some Observations on the Problem of Failures, the Effects of the Changes of Design and Manufacturing Processes
Authors: Jacobson M. A. I. 
Published: June 2010

The paper indicates that the problem has arisen in the last 10 years and is related to the increase in speed and output of automotive petrol and diesel engines. Failure incidence is furthermore associated with the change over from gear type to the cheaper multi-lobe constant displacement type lubricating oil pump. The latter have a very pronounced cycle of high torque pulses. A similar severe cyclic loading of the gear teeth is experienced when driving a distributor type diesel fuel injection pump. Changes of component design leading to reduced gear tooth loading are beneficial but cannot compensate for insufficient quality of surface finish of the tooth flanks. Failures of four distinctly different types of drives are illustrated and cause of failure analysed in detail. The part played by lubrication and oil additives is discussed. The author suggests that no drive will be successful unless the surface finish roughness of the tooth flanks is equal to or less than the oil film thickness generated. This film thickness diminishes rapidly with increase in sliding velocity and/or lubricating oil temperature. A relationship between tooth surface finish roughness and maximum safe tooth sliding velocity is demonstrated, based on the analysis of success and failure of 14 different engine types. The importance of obtaining a consistent quality of tooth flank surface finish is stressed and manufacturing methods of obtaining this are compared. The information on hobbing, shaving, grinding, lapping, buffing, phosphating, cutter blunting, shaving techniques for difficult abrasive and hard materials, detailed floor to floor production times etc. can be safely applied to gears of automotive proportions generally. The author gives a summary of his findings concerning successful and unsuccessful combinations of materials for worm-wormwheel as well as crossed-helical-gear drives. The stage by stage tooth flank surface finish improvement of an extremely successful crossed-helical-gear drive is followed through its different phases of production and demonstrated by photographic records.
Car Brake Usage and Test Schedules
Authors: Mackenzie D. K. , Newcomb T. P. , Watton B. 
Published: June 2010

An investigation of car brake usage has been made on different routes and also on hills of various slopes. From the results obtained on a number of cars it has been found possible to define two parameters V0 and M, which describe the type of route and the manner of driving over the route respectively. V0 is the speed at which it would be theoretically possible to drive over a route without applying the brakes. The range of values of V0 was measured over short sections of four routes each approximately 100 miles in length. M was found to relate the average journey speed to V0 and the maximum speed of the vehicle. The range of M was obtained by observing the behaviour of a large number of private cars over part of two routes. The brake application and release speeds, the brake line pressure and the deceleration were measured at every brake application. The drag losses at given speeds were also obtained and the amount of energy dissipated at the brakes calculated. On any journey on a flat road the energy dissipated at the brakes per unit weight of vehicle is shown to be related to V0, M and the journey speed. The work done by the brakes per unit weight of vehicle has also been measured when motoring down hills and shown to be dependent on the slope of the hill. The results of the brake usage study have been used to formulate test schedules to simulate normal, fast overload driving, and conditions encountered when motoring down hills and Alpine passes. These tests are given in tabular form for cars of maximum speed in the range 70 to 120 mile/h.
Some More Light on Diesel Combustion
Authors: Alcock J. F. , Scott W. M. 
Published: June 2010

This paper discusses the process of combustion, as revealed by high speed cinematography, in a small high speed diesel. Two direct injection types and one prechamber type were examined, and combustion sequences are shown. The phenomena are complex, but the main features are: (1) In small engines much of the fuel strikes the chamber wall and moves along it. (2) Swirl is greater than has hitherto been supposed, squish much less. (3) Most of the flame is of the carbon-rich diffusion type. (4) Soot from very rich mixture is always formed at high loads, but can burn later leaving a clean exhaust. (5) Combustion knock does not seem to be related to the total fuel in the chamber on ignition, but rather to the amount of fast burning mixture present.