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Technical Paper

TURBULENCE

1921-01-01
210044
This paper is a collection of notes gathered from investigation of the subject in the literature on the development of internal-combustion engines and memoranda set down during a long series of tests. The paper includes a discussion of the physical and chemical aspects of the subject and sets forth a working theory that has proved of value. Several methods of measuring turbulence are stated. After outlining the history of the subject and giving references, the effect of turbulence on flame propagation is discussed at length and illustrated by diagrams. Two methods of producing turbulence are then copiously illustrated and described, inclusive of seven diagrams showing characteristic turbulence in typical cylinders. Following the description of the methods of measuring turbulence, the effects of turbulence in performance are summarized under 10 specific divisions.
Technical Paper

FLAME

1921-01-01
210045
Stating that the knowledge now available does not permit an exact scientific definition of flame and giving the reasons, in this paper the author regards flames as gases rendered temporarily visible by reason of chemical action, discusses their physical rather than their chemical aspects and, unless otherwise indicated, refers to the flames of common gasoline and kerosene only. To gain a reasonably clear understanding of the requirements and characteristics of the different kinds of flame, it is necessary to begin with a study of atoms and molecules. The author therefore discusses the present atomic theory, the shape of the atom and molecular structure, and follows this with a lengthy detailed description of the beginning of combustion. The requirements and characteristics of the inoffensive variety of combustion are considered next and nine specific remedies are given for use in accomplishing the burning of heavy fuels with a blue flame in present engines.
Technical Paper

IMPORTANT FACTORS IN PISTON-RING DESIGN

1921-01-01
210050
The purpose of piston rings in an internal-combustion engine is to reduce to a minimum the leakage of gas from and the seepage of oil into the combustion-chamber. Asserting that the widely held idea that the leakage of gas past the piston can be eliminated by the use of good piston-rings is incorrect, the author states three possible paths for such gas-leakage and, after commenting upon them, discusses diagonal and lap joints and the subject of leakage with special reference to them. After considering the design of rings for gas-tightness, the author shows a fortunate mathematical relationship, in connection with the application of uniform radial pressures, regarding the bending-moment stresses. Oil leakage is treated in a similar manner and the conclusion is reached that the properties of the material used are of extreme importance.
Technical Paper

AUTOMOBILE FRAME STRESSES

1921-01-01
210051
Following a review of some of the factors that are productive of excessive weight in a motor vehicle, which causes fuel wastage, and a statement that a more thorough standardization of frames and other parts would eliminate much of this waste, the author presents in detail frame-stress calculations intended to enable the designer to proportion frames and parts with this end in view. Shearing stresses are treated in a similar manner and for a similar reason, use being made of diagrams that facilitate analysis of specific instances cited and being inclusive of a table of bending-moments derived from the diagrams. Laboratory tests of the ultimate strength, elastic limit, yield-point, elongation and reduction in area of materials are then described in some detail and the results obtained stated.
Technical Paper

ELEMENTS OF AUTOMOBILE FUEL ECONOMY

1921-01-01
210048
The paper analyzes and states the factors affecting the power requirements of cars as rubber-tired vehicles of transportation over roads and the factors affecting the amount of power supplied the car as fuel to produce at the road the power required for transportation. Quantitative values are given wherever possible to indicate the present knowledge of the relation between the factors involved, and the text is interspersed with numerous references, tables, charts and diagrams. Among other important factors specifically discussed are mixing and vaporization, charge quantity control, the heat of combustion, gas-pressure, transformation loss and power transmission efficiency. Six appendices contributed by other associates of the Bureau of Standards are included.
Technical Paper

DEVELOPING A HIGH-COMPRESSION AUTOMOTIVE ENGINE

1921-01-01
210049
The paper is divided into three parts; the fuel problem, the selection of the most economical internal-combustion engine for adaptation to automotive purposes and the details of the development work undertaken. After stating the fuel problem, inclusive of production, volatility and price charts, the methods of increasing the engine-fuel supply, the characteristics of present engine fuels and general considerations regarding the selection and adaptation of the most economical engine are discussed. Classifying internal-combustion engines as being of low, medium or high compression, the essential factors, advantages and disadvantages of each class are commented upon in detail. High-compression engines are classified, as to their method of injecting the fuel into the combustion-chamber, into the three general classes of air, gas-pressure and mechanical injection.
Technical Paper

THE METALLURGIST AND THE TRACTOR

1921-01-01
210055
The author considers first the materials available for construction, in connection with the S.A.E. standard specifications, and presents a comparison of the different metals with comments thereon. In regard to metallurgical problems the designer's first task is to determine what the various stresses in the parts are and their magnitude; hence, a true appreciation of the terms “shock” and “fatigue” is necessary; a somewhat lengthy explanation of their meaning is given. The construction features of the different parts of the tractor are treated in general, no attempt being made to cover details; comments are presented on front axles, wheels, bearings, cylinders, valves, valve-seats, transmissions and gears. Heat-treating is then considered in some detail, three specific reasons for annealing before machining being given and five which are governing factors in regard to heat-treatment in general.
Technical Paper

EUROPEAN AND AMERICAN AUTOMOBILE PRACTICE COMPARED

1921-01-01
210054
The paper surveys the differences between American and European conditions in the automotive industry and then considers briefly the reasons for them. The governing conditions are stated and their effects are traced. The subjects discussed include motorcycles and small cars, road conditions, car idiosyncracies, selling conditions in Europe, and a comparison of design in general. The differences of practice are stated and commented upon. Six specific points are emphasized in the summary. The author states that the outlook for American cars the world over is seemingly good. In recent American designs, equal compression - volumes are often assured by machining the heads; six-cylinder crankshafts have seven bearings and are finished all over in the circular grinding machine; pressure lubrication is used for all moving parts of the engine; and in all ways the highest practice is aimed at. America is trying to improve the quality without increasing the cost.
Technical Paper

CUSHIONING IN MOTOR-TRUCK DESIGN

1921-01-01
210053
The majority of the reputable truck builders are attempting to build a high-quality product that will operate over a period of years with the minimum of maintenance expense; however, many designers lose sight of the effect of shocks and strains, which is of even greater importance. Stating that a truck is scrapped for some one or a combination of the three reasons of obsolescence of design, wear on vital parts that cannot be replaced economically and failure of parts due to shock loads, fatigue or crystallization, the author comments upon these and then discusses chassis strains under five specific headings, illustrations also being given.
Technical Paper

AUTOMOBILE INSURANCE

1921-01-01
210059
Presuming that insurance protection against the theft of automobiles will continue to be furnished, the author considers ways and means of restricting the losses to an extent that will permit the protection afforded by insurance to be provided at non-prohibitive cost. The use of the word “retard,” in contrast to “prevent” or “protect,” is emphasized because the property of mobility is a primary essential of the automobile and, speaking generally, the prevention of theft while mobility persists is not possible. This has been recognized by classifying automobile locking devices as “theft retardants,” it being believed futile to proceed on the theory that prevention is practicable. The automobile-theft problem from the insurance viewpoint is stated and theft retardants described and commented upon. Theft and other forms of automobile insurance are discussed, the relation of design to insurance is outlined and the schedule method for automobile fire-insurance classification is presented.
Technical Paper

PRACTICE AND THEORY IN CLUTCH DESIGN

1921-01-01
210052
The objects of this paper are to (a) set down in convenient form for reference purposes particulars concerning American and British practice in clutch design, (b) compare the advantages and disadvantages of various types of clutch and (c) give some notes on the theory of design without attempting comprehensive treatment of the numerous factors involved. The descriptive portion deals almost entirely with clutches used on passenger cars and trucks, but some of the clutches described are applicable to other automotive uses. The notes on the theory of design apply in general to all automotive clutches. The clutches considered are divided into the four general classes of cone, single-plate, multiple-disc and shoe-or-band types, these being discussed at length and illustrated with drawings. After a consideration of the details of their design and a brief presentation of the subject of clutch brakes, the notes on the theory of clutch design are presented.
Technical Paper

ARTIFICIAL VERSUS NATURAL MEANS OF DRYING PAINT

1921-01-01
210056
The author describes a process for drying coats of paint and varnish more rapidly than is possible with natural means, by adding heat and moisture simultaneously to the air surrounding the siccative coatings, through the employment of mechanical devices. The use of a fan and conditioning equipment to produce air circulation allows the process to be adapted readily to modern factory-schedules. Atmospheric conditions suitable for drying are discussed at some length as being a composite of sensible temperatures and relative degrees of humidity, and several humidifying devices are described and illustrated. Color control of paint by this means of drying is mentioned, examples being given, and numerous photographs showing installations of artificial drying equipment in use at various automobile plants are presented.
Technical Paper

MUTUAL ADAPTATION OF THE MOTOR TRUCK AND THE HIGHWAY

1921-01-01
210057
The aim of this paper is to stimulate thought on how to accomplish the greatest possible economy in transportation over highways. The fundamental thought is that the expense of highway transportation involves a large number of items that can be grouped into those directly concerned with motor-truck operation and those involving the highway, and that highways and motor vehicles should be adapted mutually so that the greatest economy of transportation will result. Urging that the automotive and the road engineer cooperate in gathering information that will give them a more definite basis upon which to design the truck and the road, the present rapid destruction of roads is discussed and remedial measures suggested. The designing of motor trucks to conserve the roads is treated at some length and a plea for cooperation between the Society and the highway officials is made.
Technical Paper

REQUIREMENTS OF AERONAUTIC POWERPLANT DEVELOPMENT*

1921-01-01
210060
In discussing the probable trend of aeronautical powerplant development and subsequent to a brief survey of the present situation, the authors review the evolution of various engine types and analyze the effect of their characteristics on airplane performance, considering also the proper installation of airplane powerplants. The problem now confronting the industry is one of establishing standard types for the powerplants required by each service and setting up reasonable power requirements for each unit. For each service, factors must be developed to permit the making of correct comparisons of the performance of the different engines. The future types of engine are considered at some length and special reference is made to radial engines. Curves and tabular data accompany the discussion of variations in engine elements and the characteristics of a high-speed airplane are treated in a similar manner.
Technical Paper

THE APPLICATION OF STEAM POWER TO AN AUTOMOTIVE TRUCK

1921-01-01
210029
The paper describes the steam-operated 2-ton truck developed by E. C. Newcomb and the author. It has a direct drive-shaft from the engine to a rear-axle worm, with a 5 to 1 gear-reduction at the axle, and is operated without any transmission or clutch. The engine has been simplified since the author's first report on it in 1919, the changes relating to valve-gear, crankshaft and cam design. After presenting illustrations and describing them, the author gives nine specific advantageous features in this steam powerplant and comments upon them, submitting charts of torque curves which are analyzed. The engine control, fuel, oil and water consumption are next described and discussed and the results of acceleration tests are then shown in tabular form, with comments thereon.
Technical Paper

THE CARE AND MAINTENANCE OF MOTOR TRUCKS

1921-01-01
210030
The object of this paper is to point out some of the difficulties of motor-truck maintenance and to suggest lines of improvement. The buyer and user of a motor truck sometimes experiences disappointments due to the lack of coordination between the engineering and sales departments of a truck company. The term “service” is often misunderstood by the purchaser and misrepresented by the salesman, which results in dissatisfied customers. Salesmen should have accurate information on the service policy of their company and on all guarantees which they are authorized to make. After rehearsing many of the difficulties encountered in truck maintenance, the author discusses in some detail the needed improvements in truck design, passing then to details of maintenance practice and methods of handling repairs.
Technical Paper

TRACTOR SERVICE REQUIREMENTS

1921-01-01
210031
The paper treats of the service, commercial and technical aspects of the subject in turn. The author calls attention to the fact that there can be no such thing as free service, because the customer pays in the end, and gives a specific definition of service. He argues that the engineering departments should urge upon merchandising departments intelligent distribution through dealers, the stocking of an adequate supply of parts and the maintaining of a well qualified mechanical force for the purpose of making engineering development work in the form of farm power automotive apparatus effective. There is a great need for a suitable system of training mechanics for tractor service work, and there should be a definite plan to assure that men making repairs and adjustments in the field are well qualified.
Technical Paper

NEBRASKA TRACTOR TESTS

1921-01-01
210033
Before taking up the results of the tests, the author states briefly the provisions of the Nebraska tractor law, the kind of tests conducted and the equipment used. Applications covering 103 different tractors were received during the season; of the 68 that appeared for test, 39 went through without making any changes and 29 made changes. The results of the tests are described and illustrated by charts. The fuel consumption was studied from the three different angles of volumetric displacement, engine speed and the diameter of the cylinders, the tractors being classified accordingly and the results presented in charts which are analyzed. The weaknesses of the tractor as shown by the tests are commented upon at some length with a view to improvement of the product.
Technical Paper

THE GERMAN SUBMARINE DIESEL ENGINE

1921-01-01
210035
The author describes the type, size and general characteristics of the engines with which the German submarines were equipped at the time of the surrender, after having personally inspected 183 of them at that time, and then presents the general details of construction of these engines, inclusive of comments thereon. The maneuvering gear for such engines receives lengthy consideration and the reliability of engines of this type is commented upon in some detail, the author having confirmed his opinion that the German submarine engine is extremely reliable. One of the controlling factors in the design is that the Germans had investigated steel casting to the point where the successful production of steel castings was an ordinary process, and the author believes this to have been largely responsible for the success of the German submarine engine.
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