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Technical Paper

AN ANALYSIS OF MACHINE-TOOL MAINTENANCE

1925-01-01
250060
Machine-repair analysis and a criticism of present-day equipment, with analytical tables based on data collected from a 5 months' study, are followed by conclusions relative to the reliability of present-day equipment. Eight types of common machine-tools are considered and the maintenance advantage of one over the other is deduced from the consolidated tables based on monthly reports. A comparison of each class of machine-tools with the others is made, as well as a summary of the weaknesses of each class from the frequency of repairs of the elementary parts. The attention of the builders is drawn to the conditions that the shop encounters with their equipment. A maintenance budget-system is described that has been installed in one plant to give the men a comparative idea of particular equipment that is running in excess of the budget time. It also serves in lieu of an inspection of the conditions of the equipment and is an indication of the time when overhauling is advisable.
Technical Paper

MAKING MACHINE-TOOLS SAFE

1925-01-01
250061
Evolving gradually since the time when opinion prevailed that accidents are unpreventable, modern safety methods have come into being and successfully organized effort concentrated on their application in industry has accomplished an amazingly effective system of accident prevention. In the automotive industry, effort focused on preventive measures looking toward the elimination or reduction of casualties and fatalities has resulted in greatly increased conservation of life and property; but, as new conditions and new demands continually appear, it is evident that new methods, new means and new modifications must be continually in process and that putting these forces into production requires concentrated scientific study, forethought and executive ability.
Technical Paper

TRAINING EMPLOYES IN PRODUCTION WORK

1925-01-01
250062
Successful production demands the greatest volume of output with the least amount of effort. It is of prime importance in industry, and its slogan is the elimination of waste, considering always the worker, surroundings, equipment and tools and the methods or motions used. Therefore, it is necessary to give attention to training employes in production work. The paper evaluates training in terms of production and formulates the elements that have proved effective, the aims of such training being to develop a better worker in the particular job, to produce a better member of industry and to create a better member of society. The worker always must be judged with relation to his work, and no more important psychological test exists than that of aptitude for the job.
Technical Paper

THE TESTING OF SHEET STEEL

1925-01-01
250064
Will sheet steel that is to be used in the manufacture of automobile parts form the parts for which it is intended without breaking, buckling or pulling coarse at the sharp corners is a question, the answer to which is sought through a series of tests applied to samples of the material by the Packard Motor Car Co. Three sheets are selected from different parts of every 1000 sheets received. After sections have been removed from the ends of these sample sheets, four test pieces are taken from each sheet at specified locations and these last samples are subjected to Erichsen, Rockwell and tensile-strength tests, each of which is discussed.
Technical Paper

TRAINING THE FOREMEN OF A MANUFACTURING ORGANIZATION

1925-01-01
250063
Industrial development has out-run foreman development, in the author's opinion. He believes that management should be alive to the changed status of the foreman and that it should train him definitely to accept a broader responsibility. Clarification of the situation should start with the assumption that the departmental foreman is to be held definitely responsible for every activity that affects his department; but, obviously, he cannot be given direct authority over certain functionalized services that very directly affect the operation of his department, and he must, therefore, develop that higher type of executive ability which can obtain results without the club of direct authority. In short, instead of conceiving the departmental foreman as the master craftsman of his department, he should be looked upon as the business manager of his department.
Technical Paper

DIE-CASTINGS MADE OF NON-FERROUS METALS1

1925-01-01
250065
Subsequent to an historical review of die-casting, briefly stated, the author covers the subject of present die-casting practices comprehensively and conveys a large amount of specific information. Because many different methods of producing castings exist outside the sand-casting realm, he says that some confusion prevails as to the exact definition of the term “die-casting.” Such castings may be produced in metallic or in non-metallic long-life molds, or in combination with destructible cores. They may be filled by gravity and known as “permanent-mold castings”; or by centrifugal force and known as “centrifugal castings”; or by filling the mold by gravity and, after the outer skin has become chilled, pouring out the excess metal. The last named are known as “slush castings.” On the other hand, a die-casting may be defined as a casting formed in a metallic mold or die, from metal subjected to mechanical or gaseous pressure while in the molten state.
Technical Paper

SOME ASPECTS OF AIRCRAFT-ENGINE DEVELOPMENT

1925-01-01
250066
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.
Technical Paper

RECENT DIESEL-ENGINE DEVELOPMENTS

1925-01-01
250038
What the Diesel engine has done, its possibilities of development and future application to automotive service are major topics of the paper. When modified for automotive use, the author asserts that the Diesel engine would not only allow the burning of cheaper fuel and provide greater fuel economy, but give immediate opportunity to use the two-stroke cycle; that is, it would generate about twice the power for an equal weight of mechanism, compared with present power attainment. In addition, the two-stroke cycle makes possible partial or entire elimination of exhaust-valves, exhaust through ports being better in every respect, and the Diesel-engine principle affords the possibility of a two-stroke-cycle double-acting engine in which, theoretically, four times the power of the present gasoline engine would be available.
Technical Paper

STEAM-COOLING1

1925-01-01
250037
Piston friction is much the largest item of mechanical loss in an engine, amounting to fully one-half the indicated horsepower at light loads. Although opinions differ as to the most desirable temperature of the jacket-water for full-load operation, no question has arisen as to that for part load. It should be as high as possible, in order that piston friction can be reduced by keeping down the viscosity of the oil on the bearing surfaces, and that complete vaporization of the fuel may be secured. By reducing the friction of the piston and improving the vaporization, steam-cooling increases economy, which, on a number of cars of different makes, has been found to average 20 per cent more miles per gallon. Water is practically a non-conductor of heat. Boiling water, or a mixture of water and steam, is far more effective for cooling than is water that is not boiling.
Technical Paper

MACHINE FOR COMPARING THE LUBRICATING PROPERTIES OF OILS

1925-01-01
250035
The usual laboratory tests of lubricants do not indicate to what degree a given oil may possess the important property of “oiliness,” a property, apparently independent of viscosity, upon which the ability of an oil to maintain lubrication between two surfaces under high pressure seems partly to depend and by which some sort of extremely tenacious and adherent thin layer of oil is held on one of or both the rubbing surfaces so that metal-to-metal contact is in part prevented. Oiliness is of special importance in metal-cutting operations and in some machine parts, such as gear teeth or cams under heavy loads, in which the pressures between the surfaces are far in excess of those permitted in plain bearings. With a view to investigating the behavior of various lubricants, cutting compounds and bearing materials under high bearing-pressures, a special machine has been designed, of which a description is given and data are presented.
Technical Paper

FUEL FROM THE SERVICE STANDPOINT

1925-01-01
250036
As the automobile, a chemical factory on wheels, converts gasoline and air into energy for propelling itself and its load, its prinicpal problems of operation center on the properties and impurities of the raw materials, the utilization and disposition of the by-products and the proper maintenance of the plant equipment. After discussing the nature of gasoline, the author enumerates the five sources from which motor fuel is derived. The major part of the gasoline is said to be obtained directly by distillation from petroleum; about one-quarter of American gasoline, to be secured by the cracking of heavier petroleum oils; about one-tenth, to be gasoline that is separated from natural gas; from 1 to 2 per cent, to consist of benzol and similar material; and fuel used in some sugar-producing localities, to comprise alcohol made from molasses.
Technical Paper

FUNDAMENTALS OF BRAKE DESIGN

1925-01-01
250042
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.
Technical Paper

HISTORY OF AUTOMOTIVE-CLUTCH DEVELOPMENT

1925-01-01
250041
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.
Technical Paper

TRANSMISSION NOISES AND THEIR REMEDIES

1925-01-01
250040
Discordant sounds from transmission gears can be avoided by using gear-tooth ratios that give pleasing combinations of tones; a 5:6 ratio produces a minor third note; a 4:5 ratio, a major third; a 2:3 ratio, a perfect fifth; and a 2:1 ratio, an octave. Careful attention to selection of relative tooth-numbers, therefore, will aid greatly in the production of quiet or un-objectionable transmissions. Careful design and accuracy in the production of gears will not, alone, insure quiet operation; the shafts must be sufficiently rigid to hold the gears in proper operating position and large flat surfaces in transmission cases, which act as sound amplifiers, should be avoided. Bearings may also be noisy through faults of their own or because of improper mounting and alignment.
Technical Paper

SOME RECENT WORK ON UNCONVENTIONAL TRANSMISSIONS1

1925-01-01
250039
If automobile builders had available a variable transmission that was capable of giving any ratio between the upper and the lower limits and that substantially was equally satisfactory at all ratios from the viewpoint of efficiency of transmission, wear and quietness of operation, a comparatively large reduction-ratio would be used most of the time, because that would assure the greatest fuel-economy. Several types of continuously variable gears have been used on automobiles, or merely suggested for such use. Of these, the systems employing belts and friction discs or wheels need hardly be considered at present, because of their bulkiness and comparatively low efficiency.
Technical Paper

ELEMENTARY DYNAMICS OF VEHICLE SPRING-SUSPENSION 1

1925-01-01
250046
Riding-discomfort from road inequalities can be divided into two general classes, of which the first, direct discomfort, includes jolts, jars and unpleasant forces that occur during, and as the immediate result of, passage over the inequality. The extent of these discomforts depends chiefly upon the magnitude of force exerted against the passenger and the rate at which this force is applied. The second type of discomfort may be called potential and includes such motions of the car, following, and resulting from, passage over the road inequality, as lead to “not holding the road,” extreme pitching motion, or throwing the passengers off the seat and the like. This potential discomfort is more or less proportional to the amplitude of spring motion and the extent to which this motion interferes with the uniform straight-forward progression of the car. The springs of a vehicle supported at the front and the rear seldom operate individually.
Technical Paper

DEVELOPMENT AND DESIGN OF HYDRAULIC-BRAKE UNITS1

1925-01-01
250045
The principles of hydraulics have long been known and the use of a liquid for transmitting power has proved safe and reliable in many applications, notably in the operation of passenger elevators. Hence it was natural to make use of these principles in a device for controlling an automobile under traffic conditions that demand an efficient and dependable braking mechanism. The ideal of equalized braking-effort is sought but variation in the coefficient of friction between brake-bands and brake-drums and between tires and road introduces complications, so we must be content for the present with the nearest possible approach to equalized pressure at the brake-bands. In the hydraulic system, pressure is transmitted equally throughout the liquid and to the levers that actuate the brake-bands. These levers are also designed to transmit the pressure equally to the brake-bands on all four wheels.
Technical Paper

MODERN FOUR-WHEEL MECHANICAL BRAKING-SYSTEM1

1925-01-01
250044
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.
Technical Paper

THE TREND OF LARGE COMMERCIAL MOTOR-VEHICLE DESIGN

1925-01-01
250049
Reviewing the present transportation problem in regard to its demand for larger motor-vehicle units of transport, the author says that the motor truck is proving to be successful in the movement of practically all local freight and that the motorcoach is meeting with greater and greater favor as the logical vehicle with which to meet the demands of the traveling public for better transportation facilities. Although the present types of motor vehicle are serving present needs in a more or less successful manner, when strict economics becomes the standard for measuring road transportation a demand will be made for vehicles that will accommodate the maximum freight or passenger loads in the minimum of street space. At speeds governed within limits of safety they will offer the utmost comfort for passengers and will haul perishable goods over long distances in quantities large enough to assure strictly economic operation.
Technical Paper

MINIMUM STOPPING-DISTANCE OF AN AUTOMOBILE1

1925-01-01
250043
Claims and counter-claims as to the deceleration possible under certain conditions, especially when applied to the legal questions arising at the time of an accident, induced the author to make an investigation of the subject. An attempt has been made to include all the variables that are of significance or of sufficient magnitude to affect appreciably the performance of a car under a given set of conditions of the vehicle or of the environment. Inasmuch as the calculations are simplified by doing so and because the difference between the amounts of deceleration and of power involved are small, the assumption is made that the maximum deceleration occurs when the wheels are locked, rather than when they are still rotating. The stopping-distances, theoretically obtained, apply to level-road conditions only.
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