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Viewing 109891 to 109920 of 110718
1925-01-01
Technical Paper
250006
DALE S COLE
Progress made in the development of electrical equipment to serve adequately the needs of motorcoach service is reviewed. Electrical loads on motorcoaches are comparatively high, including the usual head, tail and dash lamps, body-marking and destination lamps and buzzer systems. As more and more electrical energy is used, the source of supply and its control become relatively more important. Not only does the electric generating system have to meet the demands of battery charging, but it should be able to carry the connected load with no battery in the circuit. This means that not only is sufficient energy necessary, but the voltage must be regulated in such a manner that the battery can be charged without endangering the life of the lamps because of excessive voltage, and no flicker in the light from the lamps must be perceptible. All these results must be attained under conditions of variable load, variable speed and the changeable temperatures encountered in service.
1925-01-01
Technical Paper
250007
A H HOFFMAN
Tests to determine the location under the hood of a motor vehicle where the air-intake of the carbureter will be exposed to the least dust were made by the agricultural engineering division of the University of California at Davis, Cal., and the results are given in the hope that they will serve a useful purpose. Of three types of dust-screen devised to catch the dust at different locations so that it could be photographed, and still would present little hindrance to passage of the air from point to point under the hood, the most effective was one of coarse hospital gauze stretched over frames set in transverse vertical positions on either side of and above the engine. The tests were made on two phaetons and a speed truck, run for less than 3 miles and following another car on a dusty road.
1925-01-01
Technical Paper
250032
A LUDLOW CLAYDEN
Data regarding the condensation of water on engine-cylinder walls when running the engine at comparatively low temperatures were presented by the author in a previous paper to which he refers. These experiments showed that no water would be deposited when the cylinder-wall temperature exceeded 110 deg. fahr. but that the rate of deposition increased in direct proportion to the drop of temperature below 110 deg. fahr. His present paper describes laboratory tests of an engine equipped with a steam cooling-system, the object being to study the effect upon dilution of high cylinder-wall temperatures. The results show that a sharp reduction in dilution occurs as the boiling temperature is reached, and that the amount of dilution at temperatures of 212 deg. fahr., or more, is much less than would have been anticipated from the results obtained at temperatures below 212 deg. fahr.
1925-01-01
Technical Paper
250033
D P BARNARD
General laws governing the rate of flow of oil through complete journal bearings are developed in the paper. These laws are based on the assumption that axial flow obeys Poiseuille's Law and is, therefore, a function of the bearing load. Dimensional reasoning indicates that the volumetric efficiency of a bearing considered as a pump is given by an equation of a form in which efficiency equals a function of the viscosity times the rubbing speed divided by the bearing load, the length divided by the clearance and the length divided by the diameter. Experimental evidence is presented which substantiates this point of view. The general relation of rubbing speed to heat generation and oil-flow is discussed for the purpose of indicating a possible solution of certain high-speed-bearing problems. A plain bearing is, in effect, a pump in which the flow of a viscous lubricant through a passage of varying area develops a pressure sufficient to sustain the imposed load.
1925-01-01
Technical Paper
250017
W R STRICKLAND
Although wheel wabble, even with high-pressure tires, is of ancient origin and the general methods of controlling it have been well understood, its importance among present-day problems is due to the fact that the recognized specific for its treatment, namely, increasing the air-pressure in the tires, has been denied. Shimmying, as generally applied, includes wabble, or the sidewise vibration of the front wheels about the knuckle-pin, and tramping, or the bouncing of the wheels vertically, alternately on the two sides. In addition to discussing the advantages and disadvantages of the low-pressure tire, the author has enumerated the results of tests, some of which have been obtained from original research work by himself, others from the literature on the subject, with a view to determining whether shimmying is caused by defects in design, and what are the effects when certain modifications are introduced.
1925-01-01
Technical Paper
250011
ETHELBERT FAVARY
Benefits gained by distributing truck weights and loads among six wheels rather than four, include less liability to cause road destruction, greater carrying capacity and more economical operation. The author classifies the causes of road destruction under headings of excessive loads on tires, impacts between road and tires, traction effects of wheels, and braking effects and says that the remedy is to reduce load or to correct improper weight-distribution. Impacts probably contribute most destructive effects.
1925-01-01
Technical Paper
250019
B J LEMON
The balloon tire has run the gauntlet of skepticism and credulity and has received scientific and popular approval from engineers and car-owners. The reasons for its acceptance are satisfactory appearance, practicability and transportation comfort. Tire and rim sizes, masquerading for years under wrong dimensional markings, have caused immeasurable inconvenience. This condition resulted from poor standards or entire lack of standards supervision. A committee with backbone is needed to fix and to maintain standards. Rapid balloon-tire tread-wear depends on tread profile, pressure and movement. Increased inflation-pressure and a scientifically designed tread will reduce the rapidity of this wear. Tread-contact areas and pressures are pictured to explain the advantages of a properly designed tread, and to demonstrate that the casing carries an appreciable part of the tire load.
1925-01-01
Technical Paper
250042
OTTO M BURKHARDT
The object of the paper is to contribute some new and fundamental concepts to the mechanics of machinery. The scope is limited to the subject of brakes, which was found to have been somewhat neglected in the past. To make the paper self-contained, some well-established laws on sliding friction are given as groundwork. Attention is called to facts that have been ignored in some textbooks because of apparent insignificance, although they are of vital importance in the special subject of brake design. An analysis of the force relations for simple block-brakes is given first, with the intention to make clear that the equations so far available for designers are not sufficiently accurate for brakes such as are used on modern motor-vehicles and railroad coaches. Attention is called to the fact that the wear on brake liners is not necessarily an indication of high pressures but more accurately is a function of the geometric relation between the shoe and the drum.
1925-01-01
Technical Paper
250044
J R CAUTLEY, A Y DODGE
Because of the increase of traffic on the highways in the last few years, retardation has become the most vital function of car operation; and safe retardation is as necessary as rapid retardation. Good brakes are as essential as a good engine. Becoming convinced of the many attendant advantages of four-wheel brakes, the authors began an intensive study of braking, the results of which are outlined. The features of construction of the Bendix-Perrot standardized four-wheel braking-system, which include: (a) standardized and improved controls, (b) standardized brakeshoes and (c) a simplified brake-operating layout or hook-up, are described and illustrated and the advantages to be obtained with these improvements are summarized.
1925-01-01
Technical Paper
250002
PAUL H SCHWEITZER
Wide differences of opinion are expressed by automobile builders regarding crankcase-oil dilution. The theories advanced in explanation of dilution fail to elucidate some important facts and must therefore be regarded as unsatisfactory. From a theoretical investigation, the author determines the conditions under which the vapors of various fuels condense during the compression stroke of the engine and, as a result of such analysis, presents the theory that “surface condensation,” or the aggregation of the liquid fuel-particles on the cylinder-walls, is chiefly responsible for crankcase-oil dilution. First, suggested explanations of the dilution are presented, references to previous experiments by several authorities are stated and these are discussed. The effect of jacket-water temperature is analyzed, and whether any condensation of fuel takes place during the compression stroke of a carbureter engine is debated.
1925-01-01
Technical Paper
250041
E E WEMP
Reviewing briefly the history of the automotive clutch and summarizing the most interesting achievements in clutch design during recent years, the author discusses friction facings and says that the development of the asbestos-base friction-bearing has made possible the multiple-disc dry-plate and the single-plate types. For severe service, the qualifications of a satisfactory friction-facing are density of structure, together with a reasonably high tensile-strength; the coefficient of friction should be high and fairly constant over a wide range of temperature; the facing must be able to withstand high temperature without deterioration; the impregnating compound must not bleed out at high temperature; and the permeation of the impregnating solution must be complete so that the wear resistance is constant throughout the thickness of the facing. The molded and the woven types of facing are treated at length.
1925-01-01
Technical Paper
250027
L M WOOLSON
Advances in airplane performance during the last few years may be ascribed mainly to advances in aerodynamics and to improvements in powerplants. The latter have resulted in producing more power for the same weight of engine and smaller over-all dimensions for engines of the same power-rating. The accompanying paper describes two engines of 500 and 800 hp. respectively that have been recently developed by the Packard Motor Car Co. for aircraft service. When these engines are compared with previous types they are found to be more compact and to produce more power per pound of weight. When each is operated at its rated speed, the Model 1500 engine develops 100 hp. more than the Liberty while weighing 140 lb. less, and the Model 2500 engine develops 250 hp. more than its predecessor, the Model 2025, with a decrease in weight of 75 lb.
1925-01-01
Technical Paper
250066
G J Mead
Infallible performance and economical operation are the bases of successful commercial flying. Airplanes, having passed through the experimental and demonstration periods, must now prove their usefulness. Heretofore, because of military requirements, designers have fostered the use of power rather than refinement of design to obtain performance, but commercial operation demands efficiency, and in each of the four essentials, namely, dependability, size, total powerplant weight and cost, opportunity for decided improvement still exists. The requirements and limiting factors of each of these essentials are discussed in turn and the conclusion is drawn that a relation exists between the amount of thrust delivered to the air and the weight put into an airplane for its propulsion. To obtain the best over-all performance, if these terms are considered as a fraction, the numerator should have the maximum and the denominator the minimum value.
1925-01-01
Technical Paper
250070
J E WHITBECK
The personnel and the ground facilities that have produced such excellent results in the Air Mail Service are discussed apart from the flying equipment and its operation in the air. An airway is on the ground and the performance and safety of the pilots are dependent upon the ground facilities provided and the efficiency of the ground personnel. Pilots perform a highly important part in the operation of airlines and no matter how good the flying equipment may be, the desired results cannot be obtained without thoroughly trained and capable pilots. When selecting new pilots, the Air Mail Service looks for men who handle an airplane in a businesslike way and who are able, without taking unnecessary risks, to fly the ship without letting the ship fly them.
1925-01-01
Technical Paper
250067
W L GILMORE
A racing airplane seems to possess a special quality that sets it distinctly apart from the conventional type of airplane; but, unless a person has at least dabbled in its design, he cannot realize the enormous amount of time, effort and ingenuity that has been expended by the designers who have made these super-speed airplanes possible. Therefore, an outline is given of the procedure adopted in designing and producing a specific model of racing airplane, as well as an outline of the yearly progress made in development. The first procedure is to allocate the work to the various members of the engineering organization. Finally, a type of design is chosen after a series of engineering conferences, and the design section studies the detail design of the component parts. A wing section that is adapted to the design already chosen is developed, and an accurate weight estimate is made of each unit part of the complete airplane.
1925-01-01
Technical Paper
250069
J J FEELY
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.
1924-01-01
Technical Paper
240044
JOHN R REYBURN
A bumper is a bar attached transversely in front of or behind a car body to prevent contact between an obstruction and the car body or to cushion the shock of collision between vehicles. The impact-bars have various sectional forms, from flat to round and from tubes to channels, and are composed of steel, wood or rubberized fabric. The attaching devices are sometimes yielding, sometimes rigid. The evolution of the bumper is shown in the records of the Patent Office. Early types had yielding attaching-parts and rigid impact-parts. These were followed by types having a rigid bar connected with the frame by only a spiral spring, by those having channel-steel impact-bars and others having round spring-steel extending from the frame-horns. A strip of rectangular spring-steel was then used by a Western blacksmith, and later a similar non-reinforced bumper appeared which was cut in two in the middle, the ends being overlapped and the overlapped parts clamped together.
1924-01-01
Technical Paper
240045
HUGH G BERSIE
Classes of service already provided by the street-car and the passenger automobile influence the expectations of the motorbus passenger regarding the quality of transportation service afforded by the motorbus. If an operator persuades people to ride in his motorbuses, it will be because they offer safety, economy, convenience and comfort to a greater degree than that offered by competitive transportation media. Since the public has demonstrated that, under favorable conditions, it will patronize the motorbus to an extent that yields a profit to the operators, the future success of this means of transportation lies wholly within the control of the motorbus builders and those who operate it. Of the factors that determine the degree of success attained, motorbus-body design bulks very large. Discussion of the subject is presented from the viewpoint of the passenger, as the motorbus approaches him, as he enters it and as he judges the quality of transportation it affords.
1924-01-01
Technical Paper
240043
TOM W GREENE
In this investigation to determine strength and physical properties 12 motor-truck rear-wheels were tested, comprising two each of the following types: Class-B trucks, standard wood; Class-B truck, cast-steel; I-beam type; steel disc; aluminum; and rubber-cushion, each having a 34-in. diameter and a 12-in. tread. The wood, the I-beam and the cushion wheels each had 14 spokes; the aluminum and the steel-disc wheels had a solid web between the hub and the rim. All the wheels were tested without tires or brake-bands, were bushed to fit a 4-in. axle and the area of contact between the hub and the bushing was the same as that in service. Illustrations show the construction of the wheels. Requirements considered essential in a wheel were listed, and the tests were conducted to obtain data concerning them. One wheel of each type was subjected to a radial-compression test.
1924-01-01
Technical Paper
240042
WILLARD F ROCKWELL
Tendencies of the industry toward lower costs have been reflected in axle design. Large-volume business has made it worthwhile to introduce changes in the design of passenger-car and light-truck axles to increase production economy and improve design. For heavy trucks, the trend has been to keep costs down by making no changes that would involve added expense for tools, jigs, dies and fixtures. Front-wheel brakes for passenger cars have resulted in changing front-axle I-beam sections and front-spring design to take care of the increased stresses such brakes introduce. In the design of rear axles for passenger cars, no fundamental change has occurred, although the change from the full-floating and three-quarter floating types to the semi-floating axle and a change in mounting the bevel pinion are two features that seem to be coming to the fore.
1924-01-01
Technical Paper
240048
JAMES W CAIN
Referring to the McKeen gasoline-driven car and one of the gasoline-electric type that were introduced in the early part of the present century and were the pioneers among self-propelled cars for railroad use, the author ascribes their limited success to their excessive weight and to engine and transmission troubles. Both these types, he thinks, might have been developed successfully had the gasoline engine been in its present state of efficiency and reliability. The early attempts having been more or less unsuccessful, the construction of all types was discontinued during the war. More recently the progress in the design and construction of highway motor-trucks has caused them to be adapted to railroad service by applying flanged tires to the rear wheels, pivotal pony-trucks forward and a motorbus body for the carrying of passengers and a limited amount of baggage.
1924-01-01
Technical Paper
240049
W L BEAN
Gasoline rail-cars for branches of trunk-line railroads and for short-line roads have been the subject of much discussion since 1920. Mechanical officers of interested railroads, the engineers of companies building highway motor-trucks and others specializing on this subject have now developed designs to meet the different service requirements. Several hundred cars of various types have been built and are in service. The railroad with which the author is connected has in operation or on order 24 cars. Consideration of several principal factors of design is necessary if a selection is to result in obtaining equipment suitable for the particular service requirements of the carrier and if the knowledge accruing from the engineering development and operating experience of the past several years is to be of value.
1924-01-01
Technical Paper
240047
W C BROWN
General considerations that affect the attainment of adequate lighting are mentioned, it being stated that proper lighting of the interior of a motorbus is influenced by limitations peculiar to the service, such as vibration, scant headroom, a restricted energy supply and relatively large voltage-variations. Available types of bus-lighting equipment are analyzed as to their suitability, from six different standpoints that are stated. “Glare” is defined and means of obviating it are suggested, inclusive of a discussion of desirable types of finish for the interior with regard to reflecting surfaces. The severe vibration produced by many motorbuses demands head-lamps of more rugged construction than that used for the headlighting of private cars. Eight essentials for motorbus head-lamps are specified. A very large percentage of the glare and poor illumination of the motor vehicles on the roads results from improper adjustment or the lack of any means for adjustment of the head-lamps.
1924-01-01
Technical Paper
240046
A F MASURY
Substantial reduction of motorbus depreciation by materially increasing the useful life of the vehicle is an important problem now facing the automotive engineer. The author contrasts present motorbus life with that of street-cars; he finds a probable life of 4 or 5 years only for the former and 20 to 25 years for the average type of trolley-car. This, in the case of the motorbus, he says, is too short a period of usefulness and directly affects operating costs, since the increased cost of motorbus maintenance offsets its lower initial-cost. Demand for maximum comfort, safety and speed from the public and for economical operation from the operators has renewed interest in the six-wheel motorbus and given its design an impetus, although present four-wheel motorbuses of 25 to 30-passenger capacity have, and will continue to have, a very definite field and will not become obsolete due to replacement by other types.
1924-01-01
Technical Paper
240037
E H LOCKWOOD, L B KIMBALL
A portable instrument of the seismograph type has been designed for measuring the riding-quality of vehicles. Headings are made by a continuously revolving counter that automatically sums up the vertical displacements of a partly suspended weight. As the counter readings are a measure of the riding-quality, a large reading indicates poor riding and, conversely, a small reading indicates good riding. An arbitrary scale graduated into revolutions of the counter per mile of travel translates the readings into riding-quality; a reading of 10 indicates “very smooth,” 20, “good,” etc. The instruments have been calibrated in a special testing-machine in which the readings can be observed under an harmonic motion of fixed period and amplitude. Comparison of the riding-qualities of balloon tires and of cord tires, made on three different automobiles run over a variety of roads, shows results that are very favorable to balloon tires.
1924-01-01
Technical Paper
240036
JOHN A C WARNER
The ascertaining of the factors that determine the riding-qualities of automobiles and the methods employed in studying these factors and the lines along which research should be directed in an effort to improve riding conditions are proposed in this paper with a view to encouraging further helpful discussion of the riding-qualities problem. Relative to the first of these questions, the factors treated in this paper comprise (a) road characteristics with respect to the vehicle; (b) the vertical, the longitudinal and the transverse motions of an automobile, as well as small vibrations or oscillations of high frequency; (c) vehicle characteristics, such as springing, accessory control, tires, wheels, chassis frame, seating, body, engine and transmission, steering-gear, brakes, heating, ventilating and lighting.
1924-01-01
Technical Paper
240035
A B SQUYER
A good air-cleaner is an essential part of automotive engine equipment. Many types of cleaner are on the market and the user must choose on the basis of the three essential requirements of maximum cleaning efficiency, minimum attention from the operator and minimum power-loss. With respect to these three essentials, the development of a laboratory method of testing air-cleaners starts with the premise that the test for efficiency should consist of feeding in a weighed quantity of dust, and an account be made for that which is not separated by the cleaner. The first method was to insert a white outing-flannel cloth in the airstream from the cleaner. The varied degrees of soiling of the cloths from different cleaners were a relative measure of their efficiency. This method was found unsatisfactory for several reasons. An attempt was made to use a dry centrifugal cleaner of predetermined efficiency, in series with the cleaner under test, to catch a portion of the dust escaping.
1924-01-01
Technical Paper
240034
A H HOFFMAN
References are made to published results of similar tests of air-cleaner devices conducted in 1922, and the scope of the 1924 tests is described. Road tests of air-cleaners were carried out and the tabulated data are presented. Efforts were made to find out how much dust the engine would draw in if the cleaner and connections were removed and to catch and weigh the dust the air-cleaner under test failed to catch. Dust was raised by a car running about 50 ft. ahead of the test-car and, to produce heavy dust-conditions, the road was dragged with a chain attached to the car and forming a loop behind it. The leading drivers maintained as nearly as possible a constant speed of 25 m.p.h. and chose the dustiest part of the road, following the same course on all the rounds.
1924-01-01
Technical Paper
240041
R B DAY
Shimmying was noticeable before four-wheel brakes began to be used, but since that time the trouble has been greatly increased. Two kinds are distinguishable; (a) low-speed shimmying, a violent wabble of the front wheels about the king-pins without a bouncing of the front axle, and (b) high-speed shimmying, a severe bouncing of the front axle during which one hub is up while the other is down. This occurs at somewhat higher tire-pressures and at high car-speed. Believing that both forms are not correctible by changing the design of the tire and are only slightly affected by changes in the steering-gear, efforts were directed toward prevention rather than correction.
1924-01-01
Technical Paper
240040
J E HALE
Balloon tires have caused the points at which the greatest trouble formerly occurred to be reversed; the greatest wear hitherto has occurred on the rear tires; now it occurs on the front. The carcasses of old tires were heavy and thick and carried a large part of the load; balloon tires are flexible and will support very little load. The air-pressure carries the load and gives greater cushioning effect. Four-ply tires have proved to be the most satisfactory and have none of the disadvantages of high-pressure tires. Balloon tires steer harder than high-pressure tires because of lower air-pressure, which necessitates a greater area of contact. Steering resistance is caused by the load on the tire and the increased area of contact. Many designers, in making the steering gear free to overcome steering resistance, make wheel-twitching possible. Shimmying may be classified as low-speed and high-speed, the latter occurring at speeds between 35 and 40 m.p.h. and being very violent.