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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

Commercial Possibilities of Rubber-Electrodeposition Process

1927-01-01
270026
ACTUAL production-equipment for making rubber goods by the anode process has not been installed and studied to yield accurate quantitative data, but laboratory work has been begun in Akron, Ohio, and although some of the facts learned cannot be discussed by the author at this time, enough general indications have been secured to lead to belief that widely varied and valuable applications of the process will be made. Factors that influence the commercial application of any process are enumerated and the properties of rubber that the technologist usually studies to determine its suitability for specific uses are listed. Thorough comparison of anode rubber with the milled product has not been made but confirmatory experimental evidence supports belief that the process must yield stronger and tougher material than do current methods of production. The reasons for this are explained.
Technical Paper

The Electrodeposition of Rubber

1927-01-01
270025
AFTER giving a brief description of the nature of rubber latex and a review of investigations made in Europe of its physico-chemical properties, the author tells of experiments made in Rochester to develop a method for the electrodeposition of rubber particles. These proved that the process was possible but the problem of producing a coating containing all the ingredients requisite in a compound suitable for vulcanizing remained to be solved. The nature of the rubber particles and of rubber after coagulation of the particles is described and the method of rubber-plating as developed is explained. It is stated that the deposit can be built up almost indefinitely and at a very rapid rate; that the composition remains substantially unchanged during coating, and that the current efficiency is remarkably high.
Technical Paper

Cast Iron in Its Relation to the Automotive Industry

1927-01-01
270024
CAST iron is purchased on a basis of price instead of quality, according to the author, who says that this has depreciated the qualities of the material generally and caused engineers to look askance at its application. Combined with such factors is the influence of misinformation about cast iron that has been widely broadcast. Questions regarding the design of patterns and cheaper raw-materials have involved the foundrymen in controversial discussion concerning the influence of various elements to the detriment of the economic condition of the iron industry as well as that of the consumer of castings. Due to the lessening of the consumption of cast iron, the foundry world has inaugurated research to better the quality of cast iron, not only through investigations of raw materials but also by improvement in melting practice.
Technical Paper

The Single-Sleeve-Valve Engine

1927-01-01
270012
SIMPLICITY is the keynote of the only two types of sleeve-valve engines that have stood the test of time, namely, the double-sleeve, or Knight, engine and the single-sleeve, or Burt-McCollum, engine, the latter type being the subject of this paper. After noting the vicissitudes through which the single-sleeve-valve engine has passed since its first introduction in 1911 and outlining the patent situation, the author describes the mechanical construction of the valve and the sleeve-driving mechanism, discusses the inherent advantages of the characteristic twisting-movement of sleeve-valves, points out the advantages of a detachable head for each cylinder, explains the principles underlying the determination of the size, shape and number of the ports and tabulates the average timing-practice of single-sleeve-valve engines. He states that the chief advantages of the single-sleeve-valve engine are sustained operating efficiency, good power-output, and silent operation.
Technical Paper

Internal Wheel-Brakes for High-Speed Heavy Vehicles

1927-01-01
270052
The paper deals primarily with internal wheel-brakes for trucks and motorcoaches, but passenger-car brakes with similar characteristics are considered possible. A simple two-shoe internal-expanding type developed mainly by empirical methods is found to be the most practical solution in spite of relatively low circumferential contact. Self-energization is necessary to reduce driver effort with normal pedal-travel. The factors controlling self-energization are explained in detail, and the effect of difference in the coefficient of friction of brake-linings is noted. Distortion of brake-drum and brake-shoes must be limited by a drum of heavy section and by extremely rigid shoes. Rotation of cam with respect to self-energizing shoe should tend to deflect the toe of shoe away from brake-drum surface. A floating cam is necessary to balance unequal wear on the brake-shoes and assure adequate braking with normal pedal-pressure.
Technical Paper

ANTI-FREEZE SOLUTIONS AND COMPOUNDS

1926-01-01
260054
The effectiveness and the advantages and disadvantages of various substances and compounds that are used or offered in the market for use in the radiators of automotive vehicles as anti-freeze materials are discussed. These include alcohols, glycerine, salts, oils, sugars, and glycols. Properties affecting the suitability of a material or compound, or solutions of them with water to afford protection against freezing at atmospheric temperatures that are likely to be encountered are their heat capacity, freezing-point, boiling-point, specific gravity, viscosity, volatility, solubility, tendency to decompose at the boiling-point, inflammability, corrosive action upon metals, tendency to attack rubber, general availability, and price. The freezing-points of solutions of different materials vary widely at the same concentrations, or proportions to water, and also with variation of their concentration.
Technical Paper

GEAR-STEELS AND THE PRODUCTION OF AUTOMOBILE GEARS

1926-01-01
260056
Stating that the production of satisfactory gears is one of the most serious problems confronting the automobile builder, the authors give an outline of the practice of producing gears that is used by the company they represent and describe a new method for cutting the rear-axle drive-pinion by using two machines, each machine cutting one side of the teeth. Explanations are given of the various steps in the process and the reasons for stating that this method is not only cheaper but produces gears of higher quality. Numerous suggestions are made for improving gears and axles, and the claim is made that it is doubtful if the spiral-bevel gear has had a fair chance because axles usually have not been designed so that the main consideration was the requirements of the gears.
Technical Paper

METALCLAD RIGID AIRSHIP DEVELOPMENT1

1926-01-01
260026
Several years ago some of the most prominent leaders in automotive industries cooperated to form a purely engineering group that had as its primary purpose developing a type of rigid-airship construction in which the public would have confidence. It was conceived that such an airship should be (1) Fireproof (2) Weatherproof (3) Durable and permanent in structure (4) Navigable in practically all kinds of weather (5) Economical in the use of buoyant gas and ballast To meet all of these requirements it was decided, after mature consideration, that a substantially all-metal construction was imperative.
Technical Paper

VOLATILITY TESTS FOR AUTOMOBILE FUELS1

1926-01-01
260032
Elementary theories regarding the evaporation characteristics of pure substances and mixed liquids are discussed briefly and the difficulties likely to be encountered in attempts to calculate the volatilities of motor fuels from data relating to pure substances or in the extrapolation of volatility data corresponding to the atmospheric boiling-range of the fuel to the range of temperatures encountered in utilization of the fuel are pointed out. A brief review of previous methods of arriving at fuel volatility is also presented. Volatility, as applied to motor fuels, is defined as being measured by the percentage of a given quantity of the fuel which can be evaporated under equilibrium conditions into a specified volume. The weight of air under known pressures is taken as a convenient measure of the volume. The new method described is an equilibrium distillation of the fuel in the presence of a known weight of air.
Technical Paper

CAUSES OF WEAR AND CORROSION IN ENGINES

1926-01-01
260028
The paper represents a study of analyses obtained from 656 samples of contaminated crankcase-oil and states the results of cooperative research, the sponsors being the Society, the American Petroleum Institute, the National Automobile Chamber of Commerce, and the Bureau of Standards. Reliable information was sought regarding existent conditions throughout the Country and, since analyses of a large number of samples were a requisite, arrangements were made with service stations located at points representative of the Country's atmospheric and geographical conditions for the collection of samples of contaminated crankcase-oil, a uniform procedure calculated to assure accuracy of the results being enjoined. Each participating service station was requested to select 10 cars, all of the same make, to drain the oil and to refill with new oil.
Technical Paper

THE SUITABILITY OF AUTOMOTIVE WORM-GEARING1

1926-01-01
260043
Subsequent to a brief review of the development of the worm-gear drive for motor-trucks and the gear-ratios considered most desirable, the author discusses comparatively the worm-gear and the spiral-bevel gear with regard to their application for specific service, as well as with regard to their cost and length of life. It is brought out that the worm-gear is, after all, very similar in action to any sliding, or journal, bearing. A certain amount of involute rolling-action takes place in the action of the gearing, the magnitude of which increases with the gear-ratio; but the primary action is one of sliding of the worm-threads across the gear-teeth. Simple as this fact is, the prejudice fostered by many people against worm-gears can be traced to lack of appreciation of it. Due to the nature of the surfaces in contact, the best obtainable bearing takes the form of a narrow strip running across the gear-tooth, and the bearing pressures obtained are high.
Technical Paper

WORM-GEARS AND WORM-GEARED AXLES1

1926-01-01
260044
After a brief historical review of the development of worm-gears, the author deals with worms and worm-wheels in detail, presenting the subjects of proper choice of materials, tooth-shapes, worm-gear efficiency, the stresses imposed on worm-gearing and worm-gear axles. Usually, he says, the worm is made of case-hardened steel of S.A.E. No. 1020 grade; however, when the worm-diameter is smaller and the stresses are greater, nickel-steels such as S.A.E. Nos. 2315 and 2320 grades are utilized. The worm should be properly heat-treated and carbonized to produce a glass-hard surface. Grinding of the worm-thread is necessary to remove distortions. Bronze is the only material of which the author knows that will enable the worm-wheel to withstand the high stresses imposed by motor-vehicle axles, and three typical bronze alloys are in common use.
Technical Paper

ACTION, APPLICATION AND CONSTRUCTION OF UNIVERSAL-JOINTS

1926-01-01
260040
Use of the universal-joint for transmitting power mechanically through an angle has been traced back to about 300 years before Cardan's period and about 400 years before a patent on a universal-joint was granted to Robert Hooke in 1664. The first reference to use of this type of joint is found in a manuscript by Wilars de Honecort, a thirteenth-century architect. A peculiarity of the universal-joint is that, as the two shafts which it unites are rotated when at an angle to each other, it imparts to the driven shaft a non-uniform rotational velocity which becomes very erratic as the angle between the shafts approaches 90 deg. This action has been analyzed by many writers by different methods, two such analyses being cited by the author of the present paper.
Technical Paper

PROGRESS IN AIRCRAFT-ENGINE DESIGN

1926-01-01
260063
The marked advance that has been made in the last 10 years in constructional details and in performance of airplane engines and in airplane performance is reviewed, beginning with the year 1916 when the Curtiss OX-5 eight-cylinder water-cooled engine was brought to its final stage of development. The author describes briefly each type of engine produced successively by the company he represents and tells of the changes that were made to improve the performance. From the 8-cylinder V-type the constructors changed to the 6 and 12-cylinder water-cooled type and are now developing a 9-cylinder air-cooled radial engine that was built in 1925. An important field of usefulness is foreseen for the air-cooled engine.
Technical Paper

CALCULATION AND DESIGN OF COILED SPRINGS

1925-01-01
250012
In determining the characteristics of coiled wire springs, if all the component forces, including those .of torsion, transverse shear, tension, and compression, are considered, the calculation may be complicated and involved, but for practical purposes of design all can be ignored except torsion. The calculation then becomes simple. The underlying principles of the formulas that express the torsional characteristics of an ordinary helical spring are the same as those that govern torsion in a straight shaft; and the fact that the result would be the same if the shaft or wire were twisted in the opposite direction makes it clear why a coiled spring has the same stiffness in either compression or extension so long as all the coils remain open. In Begtrup's formula, as given in the handbooks, the only unknown factor is the modulus G, which is variously stated to be from 10,000,000 to 14,000,000 lb.
Technical Paper

SOME ASPECTS OF AIRPLANE INSPECTION

1925-01-01
250069
Following a description of airplane structure, the author discusses structural requirements and outlines the main features of properly coordinating the engineering and the manufacturing activities. He says that each of the three subdivisions of airplane design has its own series of calculations, these being related to predictions of performance before the machine is built, to stability determinations and to the design of a self-contained structure of sufficient strength to withstand any stresses developed in flight or in landing. He states also that no inspection is worth the name or the money spent on it that does not include constructive work and a knowledge at all times that the intentions of the designers are being carried out in detail so that the safety of the craft is assured. Materials used in aircraft should be light and easily workable and should possess the desired physical and chemical properties; they must have the specified cross-section and be free from defects.
Technical Paper

EYE-BOLT STRESSES AS DETERMINED BY PHOTOELASTIC TEST

1925-01-01
250068
Principal stresses in one type of eye-bolt have been determined in the laboratory of photoelasticity at the Massachusetts Institute of Technology by the photoelastic method. In the test, an eye-bolt, designed in accordance with a method suggested for circular eyes in a course in machine design by the Institute, was made of celluloid 0.25 in. thick, 1 in. wide on either side of the eye, with a 1.405-in. diameter of eye, and a 1.333-in. width of shank. Steel loading-plates were pinned to the broadened end of the shank and a load of 100 lb. was suspended from the bolt, which gave a mean stress of 300 lb. per sq. in. in the shank. Plain polarized light was passed through the celluloid model and the isoclinic lines, or lines of equal inclination of principal stress, were observed and recorded. Two families of lines of principal stress, designated as P and Q stresses, were determined graphically from these isoclinic lines.
Technical Paper

COORDINATING GEAR DESIGN AND PRODUCTION METHODS1

1925-01-01
250057
Periodically recurring problems of gear noise and wear which seem to arise from no specific cause frequently affect the manufacturing side of the automotive industry and especially the gear-manufacturers. While much has been written and discussed about the mathematics and geometry of gears, which should overcome all of these problems, the trouble unfortunately still persists. The paper outlines the experience of the organization with which the author is connected in solving a rather difficult problem that offered an opportunity for a more thorough analysis than did its predecessors. Laboratory and dynamometer analyses of the product showed that it compared favorably with the output, of other factories.
Technical Paper

INSPECTION METHODS

1925-01-01
250058
With the passing of the apprenticeship system and the introduction of the present method of employing unskilled labor on a piecework basis for assembling, careful inspection has become a necessity. Under these conditions, the only way in which the product can be held to the required standards is to make the component parts fit accurately. If the inspection is adequate, parts can be held to closer limits and cheaper labor can be used in the assembling process. Believing that no reason can exist for failure to maintain standards of accuracy if the ratio of the number of men engaged in production to one inspector does not exceed 15 to 1, the officials of the Buick Company have worked out a system, similar in many respects to a budget, in which a certain ratio of production hours to inspection hours is allowed in each plant, the number depending upon the nature of the work and varying from about 10 to 1 in the engine plant to about 34 to 1 in the gray-iron foundry.
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