Search Results

For many years plywood has been used for such automobile parts as roofs and dash and instrument-boards, but it was not until the closing of the European war that the extent to which this material was used in automobile construction greatly increased. The sudden requirement of airplanes created a large demand for plywood which would withstand the severest weather conditions. Glues were perfected that enabled plywood to withstand 8 hr. of boiling or 10 days of soaking in water without separation of the plies. Plywood as an engineering material is discussed. It is then compared in considerable detail with ordinary boards and also with metals and pulp boards, statistics and illustrations being given. The molding of plywood is considered with especial reference to employing plywood for surfaces having compound curvatures, and the limiting factors in the use of plywood for this purpose are mentioned.

Stating the desirability of reducing unsprung weight in motor vehicles as a recognized fact and that 75 of 100 engineers interviewed favor such reduction, the particular advantages resulting are given as improved riding qualities, economy in tire wear and better acceleration. Mathematical deductions to establish the most desirable ratio of sprung to unsprung weight are not attempted, the intention being rather to state the reasons favoring lighter wheels and axles. Unsprung weight effects depend primarily upon the ratio of sprung to unsprung weight. No data determining the most desirable ratio are available, but an investigation of the proportional weight of the unsprung and sprung parts of good-riding-quality automobiles showed it to be about 1 to 3. By constructing the wheels and the axles of light metal it is possible to maintain such a ratio, assure good riding qualities and reduce the total weight.

A four-cylinder 4 by 5-in. truck and tractor engine, designed for either kerosene or gasoline fuel and having the very low volumetric compression ratio of 3.36, was used. Only by suitable adjustments was it found possible to make it show a fuel consumption as low as 0.67 lb. per b.hp.-hr.; but with a slight variation in power and only a different carbureter adjustment the fuel consumption at 600 r.p.m. increased to about 1.2 lb., or 70 per cent, emphasizing the importance of knowing what constitutes the best engine adjustment and of disseminating such knowledge. The engine and its dimensions, the experimental apparatus and the method of testing are fully described and discussed, the results being presented in charts showing performance curves. These are described, analyzed and the results interpreted.

Design factors are considered from the thermodynamic standpoint only, which excludes several factors affecting power and economy. The problem of air heating includes a consideration of its influence on pressure, the consequent lowering of pressure being counteracted to some extent by the resulting improvements in carburetion and distribution and by more rapid and complete combustion; the effects of delayed combustion, with a study of the thermodynamic conditions and possible improvements; and the results that are actually obtainable from lean and rich fuel mixtures. Fuel economy is difficult because its factors conflict with those of power. The benefit of the expansion of any elastic working medium to economy is emphasized. Charts from previous papers, showing the ratio of air to fuel by weight, are referred to and discussed, best economy being obtained with mixtures leaner than those giving maximum power.

From a laboratory examination of the controlling relationships between carburetion and engine performance still in progress, the general conclusions so far reached include fuel metering characteristics, the physical structure of the charge, fuel combustion factors and details of engine design and manufacture. In every throttle-controlled engine, the variation in fuel metering for best utilization is inversely functional with the relative loading and with the compression ratio, but the nature of the fuel leaves these general relationships undisturbed. The physical structure of the charge influences largely the net engine performance and the order of variation of the best metering with change in load. Perfect homogeneity in the charge is theoretically desirable but entails losses in performance.

Supplementing a “more miles per gallon” movement in 1919, a series of experiments outlined by the S. A. E. Committee on Utilization of Present Fuels was undertaken by the Bureau of Standards, in May, 1920, which included measurements of engine performance under conditions of both steady running and rapid acceleration with different temperatures of the intake charge secured by supplying heated air to the carbureter from a hot-air stove, by maintaining a uniformly heated intake manifold and by using a hot-spot manifold, fuel economy being determined for both part and full-throttle operation. A typical six-cylinder engine was used, having a two-port intake manifold with a minimum length of passage within the cylinder block, an exhaust manifold conveniently located for installing special exhaust openings, rather high peak-load speed and conventional general design.

Two series of tests were made in 1918; one to determine whether the mixture giving best economy and that giving maximum power is a constant quality for all conditions of speed and power output; the other to ascertain what effect changes in the temperature of the fuel-intake system have on the quality of the mixture which gives the maximum power and that which gives best economy. The standard United States ambulance four-cylinder engine was used for these tests, its carbureter having a primary air passage, a primary fuel-jet, an auxiliary air passage with an air-valve and a secondary fuel-jet, the manifold being cast integrally with the cylinder block and a curved riser conducting the fuel mixture from the carbureter to it. The testing methods and fuel consumption measurements are described.

Since the Fifth Avenue Coach Co. of New York is the largest successful company operating motor-buses in this country, the author gives a rather comprehensive description of this company's systems and methods, stating the three main divisions as being the engineering, mechanical and transportation departments, and presenting an organization chart. Departments concerned with finance, auditing, purchasing, publicity, claims and the like, which follow conventional lines, are not considered. The engineering, research, mechanical, repair and operating departments are then described in considerable detail. Six specific duties and responsibilities of the research department are stated and six divisions of the general procedure in carrying out overhauls for the operating department are enumerated. Regarding fuel economy, high gasoline averages from the company's standpoint mean economy, well-designed and maintained equipment, and skilled and contented operatives.

The undisputed economy of the Diesel-type engine using heavy fuel oil is recognized, as no other power-generating unit of today shows better thermal efficiency. It is the result of the direct application of fuel in working cylinders. Transmission processes, such as the burning of fuel under a boiler to produce a working agent which must be carried to the prime mover, are less economical. The various factors which enter into a comparison between steam and heavy-oil installations are illustrated. The subject is treated in a more or less elementary manner. The diagrams and sketches are intended to explain the working principles of such examples of two and four-cycle engines as are now in actual operation in cargo ships, these being of the single-acting type. Double-acting and opposed-piston-type engines have been built and are being tried out. The working processes of two-cycle and four-cycle engines are illustrated and described in some detail, inclusive of critical comment.

ON the basis that it is impossible to state the case for either the airship or the heavier-than-air machine without some comparison of the two, the author discusses relatively features, points of merit or superiority and the fields of usefulness thus far disclosed in the rapid development of the craft. Progress since 1914 is outlined, a brief history to date is included and the way prepared for consideration of the possibilities of long-distance flight. A comparison of the features given emphasizes strongly the point that the airplane is mainly a high-speed, short-distance carrier, while the large rigid airship is essentially a medium-speed long-distance carrier. Each type has a distinct sphere of activity; the airship in transcontinental, transoceanic traffic; the airplane in feeding the terminals of the airship with passengers and, possibly, certain kinds of freight.

DURING the first two years of the war the author conducted in England experimental work for the British Government on the engine he describes. After brief mention of V-type water-cooled engines and the general situation as regards revolving air-cooled and radial water-cooled types, the discussion is narrowed to two distinct designs of fixed radial air-cooled engine, both of which have been tried out and seen some service. The fundamentals in which fixed radial air-cooled engines give promise of excelling are weight of powerplant per horsepower, the fuselage mounting and space required being duly considered; reliability and durability; fuel and oil consumed per horsepower-hour; streamline mounting, with armor, if desired; quick detachability of powerplant; accessibility, and freedom from certain inherent difficulties peculiar to water-cooled engines.

THE approaching exhaustion of the petroleum supply, from which nearly all of the available internal-combustion engine fuel is produced, raises two vital questions, upon the answers to which will depend the future of the automotive industry. These are (a) what fuels are to be available, from the point of view of the engine designer and (b) how much transportation can be secured from the fuel used. It is not certain that satisfactory engines can be developed to handle a wider range of fuels than those used at present. It is therefore not clear whether the trend of development will be toward two or more different grades of fuel, or toward a single mixed fuel to be used in all engines ultimately designed to burn it.

THE automotive industry is developing without due regard to the fuel situation. This situation is an integral part of the automotive field and should not be left out of account. Owing to the pressure of automotive demand, the supply of engine fuel is changing in character and price, with danger of precipitant alterations; there arises in consequence a fuel problem which cannot be adequately solved without the active participation of the automotive industry.

THE ever-increasing demand for highly volatile fuels and constantly decreasing volatility, constitute a serious problem. Synthetic fuels have been suggested as a remedy, but these require a change in carburetion methods. It is the author's conviction that, if any redesigning is necessary, this should embody a combustion method by which any of the existing liquid hydrocarbons can be utilized and further change of method obviated, if a new fuel should later be developed. The high-compression engine is presented as a solution. Proof is offered that by its adoption any liquid hydrocarbon fuel can be utilized under any temperature condition and a real saving in fuel accomplished through increased thermal efficiency. Sustained effort should be made along these lines to increase thermal efficiency and provide an engine of adequate power, flexibility, ease of control and ability to operate on any of the fuels obtainable now or later.

THE rapid development of heavy-duty trucks and farm tractors has made it necessary for manufacturers of engines used in such automotive apparatus to face problems regarding which there is no past experience to fall back upon. The necessity in both types of engine for maximum strength in all parts carrying excessive loads constitutes a problem of great importance, but in addition to it are others of the proper utilization of fuels at present available, lubrication under excessive load conditions over long periods of time; and, of nearly as much importance, the relation of fuels to lubricants and the effect of fuels upon lubricants. Moreover, information is to be acquired regarding the value of prospective fuels as power producers, the effects they have upon engines, lubricants, etc., comparisons of cost and the like. The tests recorded in the paper were made in an endeavor to ascertain some of these unknown values.

THE design of a modification of the Class B Government standardized truck engine is presented, the principal object being a saving in weight without sacrificing either durability or safety factors. The crankcase design is rigid, but the metal is distributed so that the weight will be a minimum. The crankshafts are made of chrome-nickel steel of an elastic limit of 120,000 lb. per sq. in., which further carries out the idea of durability with low weight. The connecting-rod length is slightly more than twice that of the stroke, and this, with light-weight pistons, obviates vibration, without adding weight to the engine on account of increased cylinder height. The flywheel and bell-housing diameters were selected with a view to securing enough flywheel weight for smooth running without increasing the engine weight materially. All-steel supports reduce breakage of arms to a minimum. The manifolds are carefully designed to give economical performance, even with low-grade fuels.

BUREAU of Mines refinery statistics for the calendar year 1918 show a production of different types of petroleum fuel products represented by the following approximate figures: Added to this are 3,100,000,000 gal. of crude oil, used as fuel without refining. The statistics do not distinguish the different classes of fuel oils, and the following provisional estimate has been made: Processing or refining costs for the different oils are difficult to estimate and of little significance in determining the selling price, which is controlled by the law of supply and demand. All types in the last list can be used in so-called heavy-oil engines, but the gas oil and light residuum are most desirable in the order given. They are less plentiful than the heavy-residuum type which generally cannot be used without special equipment for preheating. The proportionate yield of gas oil can be increased if a sufficient demand is developed.

THE oil engines described are for stationary or land installations and are of the “hot-surface” design with combustion at constant volume. Progress in the design is referred to and the thermal efficiency of modern designs is compared with that found in engines twenty-five years ago. Three important features are reviewed, namely: (a) Reliability, (b) first cost and (c) economy. Improvements in the design of spraying devices, and other details of construction which have brought about greater reliability, are referred to. Dimensions of large two and four-cycle oil engines are given, and the first costs of each type are contrasted. The greater economy of the modern oil engine as compared with the earlier type is explained. Indicator cards, test data, speed, weights and other details of interest are enumerated concerning the De La Vergne SI type of oil engine, this being an example of the results obtained in a modern hot-surface-type oil engine.

The author discusses the different types of material used in the production of the Liberty engine, the physical properties of the finished parts and the heat-treatments used in making them, applying the information as set forth to the automobile, truck and tractor industries. Under their several heads the different engine pans are discussed with close attention to details. Chemical analyses are given for each part and approved heat-treating temperatures are indicated. Quenching, direct and indirect, water and oil cooling, hard spots, warpage, scaling and hair-line seams are treated. The advantages and disadvantages of the Izod impact test are stated briefly.

A new type of automotive engine should be the quest of all designing engineers. Investigation has revealed the fact that 68 per cent of all tractor engine troubles occur in magnetos, spark-plugs and carbureters, the accessories of the present-day automotive engine. Four-fifths of the fuel energy supplied is regularly wasted, yet the fuel is a liquid meeting severe requirements of volatility, etc., and is already becoming scarce and costly. In an airplane, fuel is carried by engine power. In ocean-going cargo vessels it increases available revenue space. It is at once clear that for purely practical reasons the question of fuel economy, no less than the question of the nature of the fuel, becomes momentous. What fuel will do is entirely a question of what process it is put through in the engine; in what way combustion is turned into power.