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Technical Paper

Carbon-Depositing Tendency of Heavier Motor-Oils

1927-01-01
270008
THIS article reports a series of tests on the carbon-depositing tendencies of motor oils, supplementary to those reported at the 1926 Annual Meeting.4 The first investigation was concerned with conditions prevailing in passenger-car engines, the results leading to the formation by the authors of a theory explaining the relationship between certain characteristics of oils and their carbon-depositing tendencies. In the second series of tests the authors controlled the various factors to values commonly found in heavy-duty engines and in their findings confirmed the theory previously set forth. A tentative explanation offered for certain facts revealed by the tests as to the carbon-depositing tendencies of motor-oils rests on the volatility, in the combustion space of the engine, of the oils used. An approximately straight-line relationship also was established between the amount of carbon deposited per liter of oil consumed and the Conradson carbon-residue test.
Technical Paper

Effect of Abrassive in Lubricant

1927-01-01
270009
A STUDY of the performance characteristics of journal bearings when an abrasive is in the lubricant was undertaken to obtain an indication as to what effect an increase in the viscosity of the lubricant might have on the performance of the bearings of automobile engines when diluted or low-viscosity crankcase-oil is contaminated with road dust or other solid matter. The general scheme of conducting the tests involves acceptance of the common theory of lubrication of complete journal-bearings and actual operation of bearings under conditions simulating practical applications, with oils of different viscosities and with and without the addition of an abrasive. During one series of runs, an attempt was made to measure the wear that occurred. The wear on the shaft was practically negligible, but the wear on the bearings was found to have been sufficient to change the average clearance-diameter value from 1/663 at the commencement of the test to 1/597 after the test was completed.
Technical Paper

Ultraviolet Spectroscopy of Engine-Fuel Flames

1927-01-01
270002
DETAILS are given of the method of control of the engine so that quantitative and reproducible measurements of detonation and comparisons with spectra can be made. Typical data are tabulated and photographs are shown of the free-burning flames of hydrogen, carbon monoxide, methane, gasoline in a blow-torch, and the like. The spectra of explosion and of detonation in the engine confirm earlier conclusions. By means of a synchronous shutter, the spectra of radiation during the four quarters of a stroke are obtained for straight-run gasoline under detonating and non-detonating conditions for the same fuel containing tetraethyl lead, aniline and iodine as knock suppressers and for cracked-gasoline blends. The outstanding result is that, during detonation, the first-quarter spectrum extends far into the ultra-violet, that of the second quarter, a somewhat less distance; the third and fourth quarters are characterized by very little radiation energy.
Technical Paper

Apparatus and Method for Rating Motor Fuels in the Order of Detonation

1927-01-01
270004
AS the title indicates, this paper comprises a description of the construction of an apparatus and the development of a method of operating it in determining the rating of motor fuels in the order of their detonation. A Delco-light unit, consisting of a single-cylinder internal-combustion engine directly connected to a direct-current generator, was the basic outfit used but it was changed in many ways in its course of development as a testing-machine. The changes made are explained in detail. The method of testing adopted for rating a motor fuel was to match it, by trial and error, with a blend of chemically pure benzene and selected straight-run Pennsylvania gasoline. Several series of experiments were made to determine what blend or blends of benzene and the standard gasoline match a given fuel under widely different conditions of compression-ratio and spark-setting.
Technical Paper

Methods of Measuring the Antiknock Value of Fuels

1927-01-01
270003
THIS paper was prepared as part of the Cooperative Fuel Research program and presents mainly a review of published data on methods of measuring the anti-detonating qualities of motor fuels. Although detonation as a factor in gaseous explosive reactions is not a new subject, the general recognition of anti-knock value as an important quality of automotive engine-fuels is comparatively recent. Reference is made to bibliographies covering earlier work in this field, and an outline is given of work now in progress at various laboratories and universities. Ricardo's two test-engines and his methods of rating fuels in terms of highest useful compression-ratio and toluene value are described, and the applicability of his results to other engines is discussed. The British Air Ministry Laboratory, using a Ricardo variable-compression engine, compares fuels on the basis of percentage of increase in highest useful compression-ratio.
Technical Paper

Detonation Characteristics of Petroleum Motor-Fuels

1927-01-01
270005
AN examination for detonating qualities of 18 petroleum gasolines was made by the authors, the methods used being those of direct engine-tests and of chemical analysis. A single-cylinder lighting-plant engine, suitably modified, and a direct-reading detonation-indicator were utilized and they are described. The method of Morrell and Egloff was followed in the chemical analysis. This consists in determining the proportions of paraffins, naphthenes, unsaturated and aromatic hydrocarbons and calculating the aromatic equivalence of the hydrocarbons so found by the use of data compiled by Ricardo on the relative knock-reducing tendency of unsaturated hydrocarbons, naphthenes and aromatic hydrocarbons. These data indicate an equivalence expressed by the ratio 5 to 4 to 1. Experiments were made in which a constant proportion of one hydrocarbon of each class was added to a gasoline, and the detonating tendency of the resulting mixture was determined by engine test.
Technical Paper

Fuel Requirements for Engine-Starting

1927-01-01
270001
PREVIOUS papers relating to the cooperative fuel-research investigation of engine-starting have attacked the problem along two distinct lines, namely, (a) by actual tests of the time required to start engines under various conditions, such as temperature, mixture supplied and the like, using different fuels; and (b) by laboratory tests of the volatility of the same fuels under somewhat similar conditions, using the method of equilibrium air-distillation. In this paper the results of these two methods of attack are correlated. For this purpose, it was necessary to extend the air-distillation data to lower temperatures than had been used in the tests. This involved an application of the laws of the perfect gas and the well-established law governing the relation between vapor pressure and temperature. The results of the engine tests were originally plotted with the rate of fuel supplied, as ordinate, and the time required to start, as abscissa.
Technical Paper

Torsional Strength of Splined Shafts

1927-01-01
270042
C. W. SPICER, in a paper entitled Torsional Strength of Multiple-Splined Shafts,3 which was presented at the 1927 Semi-Annual Meeting, gave results of a number of tests which supplemented an earlier series of tests, conducted by him, directed toward the same object and previously reported.4 The results of these practical tests of actual splined shafts all indicate that, while the elastic-limit of the multiple-splined shaft is considerably less than that of a plain round shaft of diameter equal to the diameter of the splined shaft measured at the base of the splines, the ultimate-strength of the splined shaft exceeds greatly that of a plain round shaft of diameter equal to the base diameter of the splined shaft.
Technical Paper

Head-Lamp Focusing Mechanisms and How They Affect Law Enforcement

1927-01-01
270050
IT is common practice to provide single-filament motor-vehicle head-lamps with but one focus-adjusting mechanism. The advisability of incorporating also a vertical-focusing mechanism in two-filament tilting-beam head-lamps has been a subject of discussion. The intent of State laws is to require the proper use of lighting equipment that meets the legal requirements. Focusing is the most difficult obstacle in the way of practical enforcement of the laws. Types of focusing mechanism are described and the effect of the use of each type on the instructions issued by State motor-vehicle departments is explained at some length. Movement of the light source by the use of the different types of mechanism for focusing head-lamps is described to explain complications that attend the use of multiple adjusting-mechanisms. Head-lamps can be designed with a focal zone, instead of a focal point, so that they will be less sensitive to filament positioning.
Technical Paper

Accelerometer Testing Apparatus

1927-01-01
270045
THIS article reports research directed toward laboratory verification of deductions arrived at in Dr. Liebowitz's theoretical research.3 C. M. Manly, C. B. Veal4 and Dr. Liebowitz have been studying for some time the problem of devising an apparatus to test accelerometers. Mr. Manly and Dr. Liebowitz here summarize the results of the development work. The testing apparatus constructed incorporates an attempt to avoid the uncertain errors of any crank-motion by obtaining harmonic motion through the rotation of eccentric weights mounted on a spring-board, thus obtaining the advantage of extreme simplicity, minimum cost and at the same time avoiding the errors incident to lost motion by employing a molecular hinge. Results of a short series of experimental runs with a micrometer type of accelerometer are given.
Technical Paper

Continuation of the 1922 Report on Brake-Lining Tests1

1927-01-01
270047
A REPORT on the investigation of brake-lining materials by the Bureau of Standards was made by the author in 1922. The present paper gives information on work done in this field since that time. It places on record a summary and discussion of various test-methods and equipment at present employed by brake-lining manufacturers and others in the automotive industry. The difficulties connected with this work, resulting from the varying characteristics of brake-lining materials, are brought out. It is shown that some of the test methods in use do not furnish a basis for ready or fair comparison of different brake-linings. Other test procedures are so limited as to give only an incomplete picture of the characteristics of the brake-linings under conditions met in service; therefore, the test schedules generally require readjustment and amplification because a full and satisfactory knowledge of these materials can be obtained in this manner only.
Technical Paper

Effect of Wet Roads on Automotive Headlighting

1927-01-01
270049
LABORATORY and road tests of headlighting on dry and wet road-surfaces, with various types of head-lamp beam, are described and the effects obtained are shown pictorially and data are given statistically. The test equipment and the conditions of the tests are described. Strength of the beam was controlled and the photographs were made under standard conditions so that results would be comparable. Results obtained show that depressing the beam of a depressible-beam head-lamp when an asphalt or concrete road surface is wet greatly increases the apparent intensity of the beam above the road, evidently due to reflection from the road surface, and that this intensity extends far above the horizontal height of the head-lamp, thereby defeating the object of depressing the beam.
Technical Paper

The Effect of Wheel-Setting on Wear of Pneumatic Tires

1927-01-01
270048
THE author compares tread-wear of front and rear tires. Considering wear of rear tires as normal wear he analyses the abnormal wear observed on front tires and traces it to its causes, which are found to be camber, toe-in and imperfect geometrical layout of steering-arms and linkages. A theory of the scuffing action is developed. It is due partly to various rolling diameters at different parts of the tire tread and partly to the setting of the two front wheels so they tend to roll in slightly different directions. Reducing the camber angle to ¾ deg. and the toe-in to 1/16 in., reduces both these errors and results in longer tire-wear. No definite theory for camber is found. Toe-in depends on camber, counteracting the tendency of cambered wheels to diverge. A method is described for testing accuracy of rolling action by means of paper on a greased floor. Service stations must be put in a position to test and correct toe-in and camber.
Technical Paper

The X-Ray Testing of Metals at Watertown Arsenal

1927-01-01
270037
TESTS of metals with X-rays, as made at Watertown Arsenal, are of two classes: (a) radiographic tests in which photographic images of internal details of the gross structure are obtained and (b) diffraction tests in which images are obtained that may be interpreted to give information regarding details of micro-structure of the constituents in the metal. The present paper deals with tests in the first class. Diffraction tests will eventually result in steels that have better physical properties required for special applications in industry, but such improvement must be accompanied by elimination of defects in the gross structure of forgings and castings before the greatest utility of better steels can be realized. Radiographic testing gives pictures of defects whereby the nature of the defects can be determined, but their causes must be sought by logical deductions from other information.
Technical Paper

Reciprocating Balance in Engines of Six and Eight Cylinders

1927-01-01
270034
MATHEMATICAL analyses of the force required to accelerate the reciprocating parts of six and of eight-cylinder engines and of the axial and perpendicular components of the force needed to accelerate the connecting-rod are presented by the author. He then shows mathematically that the division of the connecting-rod into reciprocating and rotating elements is correct theoretically. Having obtained exact expressions for the forces required to accelerate the reciprocating parts and the connecting-rod and having shown that the usual treatment given the connecting-rod is correct theoretically, mathematical study is made of the reciprocating balance of six and of eight-cylinder engines for comparative purposes and comparison is made numerically between six and eight-cylinder engines having equal total weight of reciprocating parts. A study of the angular acceleration of the connecting-rod is also presented in the article.
Technical Paper

The Electric Drive as a Motorcoach Transmission

1927-01-01
270040
THE engineering factors involved in the adaptation of the electric drive as applied to the motorcoach are presented by the author, who also enumerates the limitations of design. To raise the power curve at the higher engine-speeds and within the most efficient speed-range of the engine, which corresponds generally with a piston speed of from 1200 to 1600 ft. per min., without unduly sacrificing engine torque at the lower speed, the valve-timing must be changed. The author illustrates what effect this has by presenting data obtained with a four-cylinder engine of 4¼-in. bore and 5-in. stroke, together with other tabulated data and charts. With regard to the advantages and disadvantages of the electric drive, it has been fairly well established that the greatest asset, as applied to the motorcoach, is the permissible increase in scheduled speed where traffic is congested.
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