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Technical Paper

Economics of the Chevrolet Engine

1929-01-01
290009
SIX CYLINDERS are used in the Chevrolet engine, because six cylinders give smoother action and a longer range of satisfactory performance than four. Maximum results per dollar has been the ideal in the design, and high output has been secured at a cost very little higher than for a four-cylinder engine. The piston displacement is large enough to give satisfactory performance without fine tuning. The bore is made as large as possible within the space required for water-cooling around the valves. The stroke is short, resulting in low inertia forces and a stiff crankshaft with the minimum amount of metal. Three main bearings are found sufficient, because of the stiffness of the shaft and the inherent balance of the groups of three cylinders. Positive lubrication is provided, without pressure. The overhead-valve mechanism is so proportioned and the cooling of the parts is so arranged that variations in expansion cancel each other and result in nearly constant valve clearance.
Technical Paper

Interpretation of the Indicator Card

1929-01-01
290013
TRUE thermodynamic interpretation of the indicator card must be based upon the properties of the actual medium working in the engine and must take into account the actual nature of the heat liberation. The temperature-energy diagram for the working combustible mixture and for the resultant combustion products provides for this interpretation a foundation that is universally applicable to engines using a given type of fuel. This diagram automatically includes the effect of variation in specific heat with temperature, because the entire energy content of a gas at any temperature is the energy required to raise it, at constant volume, from absolute zero to that temperature. The work done during the actual changes of state, as determined from the indicator card, can readily be represented on the same diagram, and the heat interchanges involved can be determined quantitatively by comparison with the adiabatic criterion.
Technical Paper

Report on Air-Fuel-Ratio Tests

1929-01-01
290019
TESTS conducted to determine how air-fuel ratios obtained by analyzing the exhaust gases checked with ratios obtained by measuring the air and fuel are analyzed by the author, the tests having been made on a six-cylinder 3½ x 5-in. engine and the air measured by using a Durley air-box having a 2-in. flat-plate orifice. As a check, a 1½-in. well-rounded orifice was also used with the same results. The exhaust gases were analyzed in conventional Orsat apparatus having four absorption bottles. The tests were made at a constant air-fuel ratio at an engine speed of about 1300 r.p.m. with a wide-open throttle and maximum-power carbureter-setting. Thus far, 31 samples have been taken by different men and the air and fuel were measured each time a sample was taken. Three methods of obtaining air-fuel ratios from the exhaust-gas analyses were used and compared, and the author comments upon the results obtained.
Technical Paper

Balancing Power-Output in Multi-Cylinder Engines

1929-01-01
290014
AN INVESTIGATION of the problems of fuel-mixture distribution in the cylinders of internal-combustion engines recently initiated at Purdue University is outlined by the author, who states his belief that the material submitted in his paper demonstrates that it is necessary to “get inside” an engine cylinder to obtain satisfactory data. He therefore presents and comments upon indicator diagrams from tests made on the road and in the laboratory. The effects of pulsations in the manifold of an engine having a rather complicated manifold system are studied by means of lower-loop light-spring diagrams, and diagrams obtained from six cylinders of an engine operating at about 0.7 load at 1400 r.p.m. are analyzed. The effects of changing the mixture delivered to one cylinder of an automobile engine are also illustrated and analyzed.
Technical Paper

Combustion-Chamber Design in Theory and Practice

1929-01-01
290015
POINTING out the difference between scientific and industrial progress as manifested by heat theory and engine design and the Carnot and Otto cycles, the author discusses the working principles of combustion. A simple synopsis of internal combustion is presented, followed by a discussion of influence of spark-plug location on detonation and pressure rise and some observations on overcooling and flame quenching. The reasons underlying the decision to use a particular type of engine in an automobile are commented on, and this is followed by a discussion of the limitations imposed upon induction and combustion by such a choice. The advance in combustion-chamber design is traced from the early T-head through the L-head, in various forms, the overhead-valve, the hemispherical and four-valve types. Drawings of the different heads supplement the text and some comparative power curves are included.
Technical Paper

Combustion Control by Cylinder-Head Design

1929-01-01
290016
DETONATION and shock, the two principal barriers to increased compression, are subject to a degree of control which can readily make possible the use of compression ratios in the neighborhood of 6-1 on commercial fuel without objectionable effects and without sacrifice of output. Since detonation depends primarily upon the temperature attained by the residual unburned gas, it can be controlled by combustion-chamber design which intensifies the heat transfer from the unburned gas to the walls. The shock tendency, which originates in the pressure-time characteristic of combustion, can be controlled only by deliberate incorporation of the desirable anti-shock characteristic in the chamber design by a method of calculation which is explained in detail.
Technical Paper

Inlet-Manifold Design and Fuel Utilization

1929-01-01
290017
THE results of research concerning the problem of fuel utilization in auotmotive engines are presented. A large heavy-duty six-cylinder engine was used, and the experimental apparatus and methods employed are described in the Appendix. Charts summarizing the engine characteristics at seven-eighths full-open throttle, the important characteristics determined by exhaust-gas analysis and the actual distribution of the fuel charge to the individual cylinders are presented. The characteristics indicated by these charts are discussed in some detail and the conclusion is reached that the higher engine-speeds used not only resulted in somewhat higher air-fuel ratios for the engine but also produced a more even distribution of the fuel charge to all of the individual cylinders.
Technical Paper

Economic Fuel-Volatility and Engine Acceleration

1929-01-01
290027
THIS PAPER is a continuation of one presented at the 1928 Semi-Annual Meeting and gives the results of tests made to determine the effect of the A.S.T.M. 50-per cent point on acceleration and on the most economical fuel-volatility from the standpoint of acceleration. Test made in connection with the first investigation were on three special fuels and covered a range of manifold temperatures representing the extremes of winter warming-up and summer-operating temperatures. These tests showed a consistent variation in the relative accelerations as the manifold temperature was varied and that the effect on engine acceleration of increasing the A.S.T.M. 50-per cent point volatility is negligbile under most conditions except those under which a car is operated in the summer. In the second series of tests the objective was the quantity of each of the four special fuels that would give the same acceleration as United States Motor gasoline at an air-fuel ratio of 11.5 to 1.
Technical Paper

Present Status of Equilibrium-Volatility Work at Bureau of Standards

1929-01-01
290029
THIS paper is a concluding report on that phase of the equilibrium-volatility work at the Bureau of Standards which is applicable to engine performance as affected by vaporization in the manifold. New data on bubble-points are presented and an improved method is outlined for obtaining temperatures on specific air-vapor mixtures from the experimental observations. By taking into consideration the slope of the A.S.T.M. distillation curve, the 16-1 temperature at any percentage evaporated from 0 to 100 per cent can be computed from the A.S.T.M. temperature with an average deviation of 1 deg. cent. (2 deg. fahr.) by means of simple relations which are applicable to pure hydrocarbons and hydrocarbon mixtures, of any degree of complexity, within the gasoline range. Values for other mixtures can be readily obtained from the 16-1 temperatures.
Technical Paper

The Cooperative Fuel Research and Its Results

1929-01-01
290032
Herein Dr. Dickinson reviews briefly the causes leading to birth of the Cooperative Fuel Research, the appointment of the joint steering committee to confer on program and pass upon results, the progress made in the several phases of the work, and the projects now engaging attention. An outstanding feature has been the development of harmony and cooperation among engineers of the petroleum and the automotive industries. Mutual adaptation of the fuel and the engine to each other has been the guiding principle in the work, to the end of National economy and internal-combustion engine efficiency. Projects undertaken include the determination of the grade of gasoline that affords the maximum number of car-miles per barrel of crude oil; the causes of and remedies for crankcase-oil dilution; the effect of initial volatility on starting, acceleration and general behavior of the engine; and measurement of the detonating characteristics of a fuel.
Technical Paper

A Study of Engine Oil-Filters

1929-01-01
290041
THE PAPER is a preliminary report on a study of engine oil-filters made at the University of California Agricultural Experiment Station in connection with research on the effect of character and condition of lubricant on bearing wear. It is similar in its general character to the papers, presented at the 1924 Semi-Annual and the 1925 Annual Meetings, giving data on air-cleaner tests made under the direction of the author. To determine what the engine-crankcase oil-filter removes, a number of used filters were obtained, principally from vehicles used by the California Highway Commission, the dirt and filter material removed and incinerated, and the ashes weighed and chemically analyzed. The results of this work are tabulated and the quantity of ash remaining after incineration serves as a measure of the solid foreign matter removed from the oil.
Technical Paper

Developments in Lighter-than-Air Craft

1929-01-01
290053
NOTABLE developments in 1928 that have greatly increased interest in lighter-than-air craft were the transatlantic flight of the Graf Zeppelin as an experiment in commercial transoceanic air-service, the ordering by the United States Navy Department of the construction in this Country of two rigid airships larger than any yet built or under construction, the development and construction of two British airships for long-distance passenger and mail transportation, the starting of erection of the world's largest airship factory and dock at Akron, Ohio, and the construction and operation in this Country of a number of non-rigid airships to be used for commercial purposes. Each of these developments is dealt with in order. General dimensions, major characteristics, and unique features of the Graf Zeppelin, the new Navy airships, and the projected large transoceanic commercial airships are given.
Technical Paper

Modern Friction-Materials

1929-01-01
290046
IF brake-lining manufacturers would insist on holding the values of friction coefficients to 0.3 or 0.4, many of their troubles would cease, in the opinion of the author, who asserts that the main objections to high friction-coefficients are rapid wear, greater liability to cause scoring, and instability. The first results of tests on molded brake-lining materials were so superior to tests on woven material that further development of molded materials was carried on. Regardless of the type or make of molded material tested, it was found that the friction-coefficient value remained much more uniform than did that of woven material and that, without exception, the friction value and general characteristics of molded material were not changed by wear conditions. Molded material shows longer life than woven material, according to tests, and the author thinks that possibly this is because of the completeness of the saturation of the molded material.
Technical Paper

Diesel Engines for Aircraft

1929-01-01
290057
ALTHOUGH the author and his associates have designed, built and tested a Diesel airplane-engine, a description of the mechanical details is omitted because the engine is still in the experimental stage. The general subject of Diesel engines for aircraft is therefore presented in its broader aspects. Typical indicator-diagrams of a gasoline engine and of a Deisel engine are compared as a means of ascertaining whether the pessimistic attitude that the Diesel engine cannot be made light enough for aircraft-propulsion purposes is justified. These considerations lead to the statement that, since a practicable Diesel aircraft-engine must run at speeds five or six times as fast as the stationary or marine-type of Diesel powerplants, whereas the ignition time-lag is substantially the same, it can be seen that the high-speed engine demands a different type of combustion than does the low-speed Diesel.
Technical Paper

Accounting for Depreciation as a Production Cost

1929-01-01
290070
IF the costs of almost any group of manufacturers who market the same product are analyzed, two kinds of differences will be detected, according to the author. The real differences in costs arise from superior management, higher productivity, and better disposition and utilization of capital. The accidental differences result from the failure of manufacturers to include in cost records all of the proper legitimate items of expense. Confining his treatment of the subject to an analysis of the depreciation of plant and equipment, the author states that depreciation is a decline in the value which is certain to occur as a result of wear and tear and gradual obsolescence. It is caused by the possession and use of an asset, and is therefore a part of the cost of production. The accountant attempts to recover depreciation loss in the value of the capital assets by charging it into the cost of production.
Technical Paper

Data on Machinability and Wear of Cast Iron

1928-01-01
280022
THE hardness or chemical composition of an iron is, by itself, no indication of the wearing property and machinability of the iron. Irons containing a large amount of free ferrite have been found to wear rapidly, whereas others having considerable pearlite or sorbite in their structure show good wearing properties. The presence in cylinder-blocks of excess-carbide spots or of phosphides of high phosphorus-content is deleterious, because such spots wear in relief and the material ultimately breaks out, acting as an abrasive that scores the surfaces. Causes of wear in cylinder-blocks are discussed, and nickel, or nickel and chromium, intelligently added to the iron is suggested as a means of obtaining the correct microstructure for a combination of good wearing properties and machinability.
Technical Paper

The Influence of Fuel Characteristics on Engine Acceleration

1928-01-01
280043
SELECTION of a method and development of apparatus enabling precise and detailed measurement of engine acceleration is discussed in the first portion of this paper, the latter portion of which is concerned with the experimental results thereby obtained. Previous work on the influence of engine conditions on acceleration is generally substantiated. A method is described for approximately deriving the effective air-fuel ratio delivered to the cylinders during acceleration, practical applications are suggested, and limitations are discussed. The effect of fuel volatility on engine acceleration was studied, using six fuels: Aviation gasoline; commercial gasoline; a blend composed of equal parts of the two; and three especially prepared fuels, all of which have equal 20 and 90-per cent points but differ widely at the 50-per cent point. It is shown that the relative values of these fuels for acceleration depend upon the amount of vaporization in the manifold.
Technical Paper

The High-Speed Diesel Engine as a Competitive Power Generator

1928-01-01
280055
HEREIN the author analyzes the Diesel oil-engine as a competitor of the steam engine and, more specifically, of the gasoline engine, in the stationary-power field and in the field of marine and land transportation. The two bases for judging the new as against the old are, first, suitability for the purpose, and, second, the cost of performing the required service. After reviewing other fields in which the oil-engine has shown its suitability, the author considers its suitability for automotive purposes. If it is equally suitable with the gasoline engine for motor-vehicles, that type of engine which shows lower cost for power will ultimately prevail; or, if the Diesel-engine cost is sufficiently lower, this type may be adopted for certain automotive uses even though it is somewhat inferior to the gasoline engine in suitability.
Technical Paper

How the Ford Company Gets Low Production Costs

1928-01-01
280063
ECONOMIC factors applying to mass production are dealt with in an endeavor to show how, by following certain laws of manufacturing management based on economic laws, the Ford Motor Co. has attained its very low production costs. Some of these laws, which were put into concrete form as recently as 1926 by L. P. Alford, are quoted, and examples of methods are given to show how they operate.
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