Search Results

The author views in perspective some facts from a purely scientific standpoint, and then shows their application to problems of the automotive industry. After reviewing the present facilities for measurement and the ability to make measurements of distances both infinitely small and large, as an aid toward a proper conception of the ultimate structure of matter, he applies this scientific knowledge in the direction of a solution of the fuel problem, which is a fundamental one because it involves the limitation of a natural resource. From 1918 and 1919 statistics, the amount of gasoline produced was something like 20 to 25 per cent of the crude oil pumped; 8 to 10 per cent is kerosene and 50 per cent is gas and fuel oil and a residue carrying lubricating oil, paraffin and carbon. Kerosene demand and production are practically fixed quantities; gasoline demands are increasing.

Kerosene has advanced to the front rank as a fuel for the farm tractor within a decade. A heavily preponderating majority of tractors burn kerosene. The history of early oil engines is reviewed and some comparative costs of kerosene and gasoline fuel for tractors, obtained from tests made in January, 1920, are given. Kerosene tractor-engine development is then discussed. The conditions required for complete combustion are the same in principle for both kerosene and gasoline, but in actual practice a wider latitude in providing ideal conditions is permissible for gasoline than for kerosene. The four classes of commercial liquid fuels usable in internal-combustion engines are the alcohols, the gasolines, the common kerosenes and the low-cost heavy-oil fuels. The alcohols rank lowest in heating value per pound of combustible. Under existing economic conditions neither alcohol nor the fuel oils require consideration as available fuels for the tractor.

Rear-drive trucks and tractors are popularly accepted as being all that is desired so long as working conditions are not bad enough to prevent their operation. Caterpillars are admitted to be able to go where it is so soft that no other vehicle can navigate, but they are considered as too slow, awkward and expensive to use where the work can be done with wheel-equipped machines. The paper discusses the field of the four-wheel drive. The experience of the Army in motor-transport work is referred to and the application of four-wheel drive to tractors is discussed in some detail.

The adoption of the present system of feeding a number of cylinders in succession through a common intake manifold was based upon the idea that the fuel mixture would consist of air impregnated or carbureted with hydrocarbon vapor, but if the original designers of internal-combustion engines had supposed that the fuel would not be vaporized, existing instead as a more or less fine spray in suspension in the incoming air, it is doubtful that they would have had the courage to construct an engine with this type of fuel intake. That present fuel does not readily change to hydrocarbon vapor in the intake manifold is indicated by tables of vapor density of the different paraffin series of hydrocarbon compounds.

A large number of tests were made in the altitude laboratory of the Bureau of Standards, using aircraft engines. The complete analysis of these tests was conducted under the direction of the Powerplants Committee of the National Advisory Committee for Aeronautics. Many of the engines were of the same make, differing in compression ratio or dimensions. The testing program included determinations of the brake-horsepower at various speeds and altitudes, or air densities, and the friction power, or the power required to operate the engine with no fuel or ignition at various speeds and air densities, with normal operating conditions of oil, water and the like. Some tests included determination of the effect of change of mixture ratio and of air temperature, and of different oils. The difficulties caused by the necessity of using indirect methods to ascertain the effect of various factors are outlined. The test analyses and curves are presented.

The comparatively slow introduction of mechanical power for farm operations has been a surprise and a disappointment to many. It is easily understandable why the deficient machines failed to sell but not so clear why really efficient outfits failed to make greater headway. No one can make a thorough study of the existing situation and conclude that any or all of the reasons given are even in a large part responsible for the slowness in adopting the tractor more generally on the farms; it is obvious that there are other strong influences. Most of these are connected with the farm business itself and, by considering the matter in relation to the individual farmer rather than farmers as a class, these influences become more clear.

The first car credited by the author as being equipped with two or more direct drives is the Sizaire-Naudin, in 1905. The transmissions of this car and of one embodying similar principles of gearing, brought out in 1909, are described and illustrated by diagrams. After the Sizaire-Naudin, the next double direct-drive transmission was the Pleukharp transmission axle, made in 1906, although the real ancestor of the present double-drive rear axles is the 1906 Pilain transmission; both are described and illustrated. Other early American and foreign forms are commented upon and diagrammed, including the Austin design, believed by the author to be the first to use a two-speed axle of the simplest and lightest possible type to provide two direct drives in connection with a separate gearset to give additional forward speeds and the reverse. Modern two-speed axles are reviewed, with critical comment and diagrams, and considerable discussion of gear ratios is included.

The paper surveys the economic and engineering aspects of the automotive industry, so that engineers can align themselves with its future development. Better performance and longer life due to improved design and materials distinguish the 1920 car from its predecessors. One of the healthiest signs in the industry is the uniform determination of practically every manufacturer to improve the quality of his product. The designer has been forced to extend himself in getting the highest possible output from the smallest possible units. This trend is very noticeable. Conditions relating to prices, the return to peace-time production, the potential demand for cars and the present supply, and the probable improvements in cars are then reviewed, the thought then passing to a somewhat detailed discussion of detachable-head engines.

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.

The only direction in which flexibility of an organization can be considered is that of successful progress. Flexibility uncontrolled is liable to lead to retrogression instead of progression. During the war, every available unit of man-power was called into use, and all specialized intelligence was stretched almost to the breaking point. This was particularly true of the intelligence in the automotive industry. Demands were made in connection with the airplane, tanks, agricultural tractor and submarine chasers, as well as the more stabilized automobile and trucks. The most skilful men naturally gravitated to the most difficult work, in the problems surrounding the airplane and the tank, and, while in general there were not nearly enough men, the scarcity of skill was more noticeable in the older branches of the industry. It was there that the necessity for a flexible organization demonstrated itself. The first necessity was a rigid base from which progress could be made.

After stressing the importance of transportation, the possible uses of the motor truck are considered. The increased cushioning and traction obtained from pneumatic truck tires accomplish faster transportation, economy of operation, less depreciation of fragile load, easier riding, less depreciation of roads and lighter-weight trucks. These six advantages are then discussed separately and various data to substantiate the claims made are presented. Following detailed consideration of transportation and operation economies, and depreciation of loads and roads, the practicability of pneumatic tires is elaborated, and wheels, rims and tire-accessory questions are studied. The four main factors bearing upon truck design for pneumatic tires are stated and discussed; emergency equipment for tire repair is outlined and a new six-wheel pneumatic-tired truck is described.

The discussion is largely in regard to the ability of a truck to deliver merchandise economically under a given set of external conditions. The matter of truck tire equipment is reviewed in the light of recent experiences of many operators and service men. The general functions of tires, securing traction, cushioning the mechanism and the load and protecting the road, are elaborated and six primary and seven secondary reasons given for the use of pneumatic tires on trucks within the debatable field of 1½ to 3½-ton capacity. The deciding factors in tire choice, those affecting time and those affecting cost, are stated and commented upon, the discussion next being focused on how tires affect these factors. Considerations relating to both truck and tire repairs are then reviewed.

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.

In investigating the forces that tend to break up and destroy roads, the most destructive of these being that of impact, the United States Bureau of Public Roads devised a method of receiving the impact of a truck on a small copper cylinder and determining its amount by measuring the deformation of the cylinder. The impact values are largely dependent upon the type and construction of the truck. Unsprung weights have a great influence upon the impact value of the blow on the road surface and a reverse influence upon the body of the truck; these effects are in two different directions. The present aim of the Bureau is to investigate this impact and the effect of the unsprung weight on the road. Most of the tests have been made on solid tires, a few have been made on worn solid tires and some on pneumatic tires. The Bureau intends to elaborate all of these tests, including different types of pneumatic tire, different unsprung weights and special wheels, such as cushion or spring wheels.

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.

The paper relates to some of the methods and apparatus which can be used to advantage in large-scale farming operations. The laying out of a production program, the transportation of men and supplies, special implements for raw-land preparation, tractor dynamometers, large tractors, special plowing and tilling implements, four-wheel-drive tractors and road haulage are discussed. An operation chart applying to an area of 40,000 acres is first presented and analyzed. Regarding hours of operation, the author maintains that with a suitable organization and proper selection of motive power and implements, tractors can be kept in motion 20 hr. per day and gives a time-table. Consideration is then given in some detail to the problems of electric lighting, the implements used in raw-land preparation, the power required for various operations, types of tractor construction, plowing and harrowing, harvesting, hauling and tractor-train schedules, the whole being copiously illustrated.

In view of the inestimable services in the development of standardized transportation rendered to the Army by the Society of Automotive Engineers, particularly during the war, the author believes it important that the Society be acquainted with the intentions and policies of the War Department regarding the engineering development of motor transportation from the viewpoint of the problems and needs of the American Army. The fundamentals of the policies on motor transportation of February, 1919, as approved by the Chief of Staff, are stated and the subsequent changes discussed in some detail. Standardization of chassis as favored by the Army receives specific and lengthy consideration and the Government standardized trucks are commented upon. The standardization of body design and parts specifications are discussed in some detail. It is the policy of the Motor Transport Corps to maintain a thoroughly adequate and efficient engineering branch, which is now operative.