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The Cadillac Company has used S.A.E. 3250 steel for at least 8 years. This is medium nickel-chromium steel. Many other kinds have also been tried. Experience has shown that transmission gears made of carburized steel are not within 30 per cent as accurate as those made of oil-treated steel. This may be because of the fact that more attention has been paid to oil-hardened than to carburized steel gears. Efforts to control the distortion of carburized gears were unsuccessful. The hardening was done in salt pots, lead pots and open furnaces, heated by gas, oil and electricity. The same thing applies to spur gears. Oil-treated steel for rear axles has not been tried. When transmission gears were made from drop-forged blanks made by the conventional pegged-out process from flat stock they became oval. Upset gear forgings are used as fast as the forging suppliers can become equipped for the work.

Graphical demonstration is given of the desirability of grinding gears that are made of carburized material. The warping of carburized gears is shown to be due to the shrinking of the carburized metal. The teeth cut on the regular commercial type of hobbing machine vary in form; those cut on a simplified hobbing machine are more accurate. Tooth forms made from oil-treated steel are much better than those made from carburized and hardened steel. The conclusion is that carburized gears must be ground, but when oil-treated and accurately cut on a simplified hobbing machine grinding may be necessary only when the teeth have become mutilated.

A practical method of nickel-plating is outlined and the various processes are described by which the Packard Motor Car Co. has been successful in producing a durable coating of nickel on automobile parts in general, and the radiator shells, the rim plates and the tire-carrier plates, in particular. These are the parts of greatest exposure, and for plating them a new system of moving-cathode tanks was installed. The three problems to which special attention was devoted were rusting, pitting and peeling. No effort was made to secure a coating of any designated depth but reliance was placed solely on the results indicated by a 24-hr. salt-spray test, which was considered to be the equivalent of 2 years' exposure to the usual weather conditions. Peeling was overcome by thoroughly cleaning the parts before plating. New equipment was purchased and laid out in accordance with the system decided upon, namely, copper-plating, buffing and nickel-plating.

Principal developments along the lines of the HS, H-16 and F-5-L types of seaplane, which were used during the war for convoy work, submarine patrol and scouting, are represented by present types PN-7, equipped with Wright T-2 engines, and PN-8, having Wright T-3 engines, a metal hull and metal tail-surfaces. Brief statements about their construction and performance are made and the subject of metal floats for seaplanes is discussed. “Training,” scouting and other types of seaplane are mentioned, and outlines given of their characteristics and performance. Launching airplanes from a catapult is described, some details of the development of the apparatus being given, and reference is made to a late development in which the catapult is actuated by the explosion of a powder charge instead of being operated by compressed air.

A grinding-machine for finishing spur-gears is illustrated and described; claims are made that it will grind transmission gears on a production basis after they have been heat-treated and will produce correct tooth-contour, smooth finish and accurate tooth-spacing, these features being necessary in producing gears that are interchangeable and that run quietly. This machine is of the generating type, its action being that of rolling a gear along an imaginary rack and using the grinding wheel as one tooth of the rack. The dished grinding-wheel is reversible, 30 in. in diameter, mounted below the gear, and can be swiveled to the right or left of the center position up to an angle of 25 deg. The work-spindle carries the indexing and the generating mechanisms at the rear, where they are accessible and yet are protected.

A statement is made of nine items suggested by the Iron and Steel Division of the Society for consideration with reference to securing greater uniformity in practice when making precision hardness-tests with the scleroscope. Plumbness of the instrument is an important factor and lateral vibrations have a bad effect; these are discussed and surface smoothness of the test-specimen is considered in relation to its effect on accuracy. Other factors treated are the influence of metal-scale on scleroscope readings, the condition of the hammer diamond, and the effect of the mass of the test-specimen. Extreme under-weight specimens, inert and over-weight masses, the effect of hardness on mass and the effect of thickness of the test-specimen receive consideration, together with points concerning testing near test-specimen edges, the effect of curved surfaces and how test-specimens are held. A lengthy comparison between Brinell and scleroscope hardness-testing is made.

Disc wheels are the answer to a demand for something better at a more reasonable price. The art of making wood wheels has been established, the machinery has become standardized and further reduction in cost is improbable; whereas the cost of suitable wood is steadily advancing and the trend, consequently, is upward. When the wire wheel was first introduced its use was a mark of distinction and to it can be traced the origin of the sport model, but its price cannot be reduced and it cannot compete, therefore, with the disc wheel on a price basis. The development of the disc wheel brought an equal distinctiveness of design and of pleasing appearance, but its progress has been different. The initial expenditure involved in the production of disc wheels is large; but the output also is large, and, as the volume increases, the prices become lower.

The author believes that the universal power unit will be direct air-cooled, but states that the direct air-cooled engine is now in the minority because, until very recently, there has not been a sufficiently broad series of established engineering facts and development work available to form a foundation for improvement. The satisfactory air-cooling of an 8 x 10-in. cylinder has been reported, and the development in a smaller cylinder of 138 lb. per sq. in. brake mean effective pressure; also, in a three-cylinder, air-cooled, radial-engine, a brake mean effective pressure of more than 125 lb. per sq. in. was developed and the engine endured beyond the ordinary expectations for water-cooled engines.

The author quotes statistics relating to the proportion of closed to open bodies and outlines the changes that have taken place in body construction in recent years. He sketches the advances that have been made and states that the question to be answered now relates to what all this improvement in manufacturing methods has accomplished toward reducing the price of a closed-car body to the consumer. He compares the percentage of public benefit in 1922 with that of 1914, excluding the period of inflated prices immediately following the war, and states that it is 10 to 15 per cent, but says also that this is an unfair comparison because of the excessive increases in the cost of labor, lumber, sheet steel and trimming cloth. An unconventional type of body, covered entirely with fabric over a foundation of wire-mesh and buckram fastened to the conventional wood-framing, is illustrated and described in detail, together with a statement of its advantages.

After pointing out that the publication of articles in the trade and technical journals, to the effect that very considerable weight-reductions in motor-truck construction with consequent savings in gasoline and tires are possible, works an injustice to the motor-truck industry and is misleading, the author outlines some of the reasons why such weight-reductions are very difficult to effect, as well as the possibilities of standardizing axle details. The use of aluminum to effect weight-reduction is commented upon and the various advantages claimed for metal wheels are mentioned. In the latter connection the author points out that, while these claims may be true, they are unsupported by reliable data. The greater part of the paper is devoted to an account of a series of tests conducted by a large coal company to determine the relative merits of wood and metal wheels on its trucks.

Cleveland Section paper - After commenting upon the two contradictory attitudes toward malleable iron in the automotive industry and outlining its history briefly, the authors discuss the differences between malleable and ordinary gray-iron and supplement this with a description of the heat-treating of malleable castings. Five factors that influence the machining properties of malleable-iron are stated. These were investigated in tests made with drills having variable characteristics that were governed by six specified general factors. Charts of the results are presented and commented upon in some detail, inclusive of empirical formulas and constants and deductions made therefrom.

The author believes the piston-ring problem to be an engineering one worthy of serious study and that it should be possible to standardize types and sizes in a way that will go far toward elminating present difficulties. It is stated that cast iron is the only satisfactory metal suitable for use in the internal-combustion engine and that the foundry offers the greatest opportunity for improvement, in the elimination of poor castings. The superiority of individually cast rings is averred and a formula for their composition is given. Leakage and oil-pumping are discussed, followed by comment upon the width and form most desirable for piston-rings; and some of the difficulties of their manufacture are enumerated, together with suggested improvements, inclusive of inspection and testing methods.

After pointing out that the general question of weight reduction is no exception to the fallacies that seem to have beset the development of the automobile from its earliest days, the author outlines briefly the problem confronting the automobile designer. The influence of the weight of the reciprocating parts on the chassis in general and the engine in particular is emphasized as being of greater importance than the actual saving in the weight of the parts themselves, it being brought out that the bearing loading due to inertia is really the factor that limits the maximum engine speed. Reference is made to the mathematical investigation by Lanchester in 1907 of the advantages of using materials of high specific-strength and the conclusions arrived at are quoted in full. A tabulation of the specific strengths of various materials used in automotive engineering practice is presented as showing the advantages of aluminum as compared with steel.

Annual Meeting Paper - Addressing the structural engineer and the purchasing agent particularly, the author discusses the relationship between them and the foundryman with regard to malleable-iron castings and enumerates foundry difficulties. The characteristics necessitating adequate gating for such castings are described and illustrated, inclusive of considerations regarding pattern design, followed by a statement of the considerations that should influence the purchasing agent when dealing with foundrymen. Possible casting defects are described, illustrated and discussed, comment being made upon casting shrinkage and machinability. Improvements in annealing-oven construction and operation are reviewed and the records of 100 consecutive heats in different plants are tabulated. The materials for casting that compete with malleable iron are mentioned and its physical characteristics are considered in some detail.

The author discusses drop-forging practice from the standpoint of the materials used, and strongly advocates a more rigid inspection and testing of raw materials to determine their fitness for use in making automotive forgings. Seven specific possibilities of actual difference between drop-forgings that are apparently identical are stated, the requirements of the inspection of raw stock are commented upon, and the heat-treatment and testing of finished forgings are considered at some length. Tabular data of the chemical analyses and physical properties of 107 different heats of carbon-steel used recently are presented and show a variation in drawing temperatures of 140 deg. fahr. in steels of practically the same chemical composition to meet the same physical-property specification, based on more than 1000 tests on this grade of steel taken from production stock. The concluding summary has five specific divisions.

The process of continuous die-rolling and the products possible with this method of manufacture are described and illustrated. The improvements that have been made were the result of efforts to produce more complicated sections by this process, with greater accuracy, and these are discussed at some length. The physical characteristics of steel that must be considered are commented upon and forming that is effected in one pass is described, consideration being given the requirements of rolled forging blanks. The cost of operation is treated and the equipment used is discussed, showing how this process differs from other methods of making the same things, as to both the operations necessary and the character of the product.

The authors state that the coefficient of friction between two rubbing surfaces is influenced by a very large number of variables, the most important being, in the case of an oiled journal, the nature and the shape of the surfaces, their smoothness, the clearance between the journal and the bearing, the viscosity of the oil, the “film-forming” tendency or “oiliness” of the oil, the speed of rubbing, the pressure on the bearing, the method of supplying the lubricant and the temperature. The primary object of the paper is to present the best available data regarding the fundamental mechanism of lubrication so as to afford a basis for predicting the precise effect of these different variables under any specified conditions. Definitions of the terms used are given and the laws of fluid-film lubrication are discussed, theoretical curves for “ideal” bearings being treated at length.

Stating that present internal-combustion engine fuel is too low in volatility for economical use and that this is the cause of engine-maintenance troubles, the authors believe that, since it is not possible to obtain the more volatile grades in sufficient quantity, the only hope of remedying this condition is to learn how to use the heavy fuel, and that the most promising method of doing this lies in the effective use of heat. As the experimental data regarding the best temperature at which to maintain the metal in a hot-spot manifold and the range of temperatures available in the exhaust gases are meager, the authors experimented in the Purdue University laboratory to secure additional data. They present a summary of the results.

The term “oiliness” is defined as that property of lubricants by virtue of which one fluid gives lower coefficients of friction (generally at slow speeds or high loads) than another fluid of the same viscosity. Its importance under practical operating conditions is shown to be greater than is generally recognized. Unfortunately, however, no satisfactory method has ever been developed for the quantitative measurement of this property in comparing different lubricants.

As a result of the general policy of the Motor Transport Corps to standardize the materials used for automotive vehicles for Army Service, in cooperation with the Bureau of Standards, the Society of Automotive Engineers and the automotive industry, the Bureau of Standards has been engaged for some time in developing a standard method for testing brake-linings. While the work is not complete, much information has been gained. This paper reports the progress of the work. The equipment developed and the methods used for both main and supplementary tests are described. Information is given regarding the coefficient of friction, as influenced by various factors. The endurance test, showing the comparative behavior of linings under conditions similar to those of severe service, is believed to be satisfactory as developed. Further work is necessary before recommending the conditions for the other test, intended to determine the relative endurance under ordinary or light service.