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Viewing 6691 to 6720 of 6739
1934-01-01
Technical Paper
340088
Alex Taub
VIBRATION formerly was classed as such without much thought as to the determination of its sources, Mr. Taub states, and then came isolation of the various causes. The first two vibrations to be segregated and vigorously attacked were the secondary inertias of reciprocating units and torsional vibration. The development of the six-cylinder engine was among the earliest attempts to eliminate secondaries, and it was also the earliest producer of torsional vibration. Dynamics, combustion roughness, torsional roughness and structural weakness, are a few of the contributing causes of engine roughness. Consideration must be given to all these factors if an engine is to be considered inherently smooth, and each is analyzed. Engine mountings should have low resistance to rotation about the longitudinal principal axis and to rotation about the vertical axis through the center of gravity, together with minimum shift of affective principal axis and vertical axis.
1934-01-01
Technical Paper
340096
R. F. Gagg, E. V. Farrar
THE rapidly increasing use of aircraft engines fitted with superchargers for improving the power output at high altitudes has focused attention on means for predicting their performance in advance of actual flight tests in an airplane. A considerable amount of engine testing has been performed in several well-equipped laboratories in the past. These results have been carefully compared to determine the degree of similarity of the performance of these engines, and to form conclusions from which the performance of other engines may be predicted. Since the gear-driven centrifugal supercharger has demonstrated its superiority for use at moderate altitudes over other types on the grounds of simplicity, capacity, weight and space requirements, the data considered are almost entirely concerned with this type. It is shown, however, that naturally aspirated engines have quite similar characteristics.
1933-01-01
Technical Paper
330047
K. L. Herrmann
A ROLLER having the same diameter as a corresponding ball and a length equal to the ball diameter has approximately four times the carrying capacity of a ball, according to Mr. Hermann. The data presented on cageless roller bearings are based upon knowledge of the carrying capacity and life of the ball bearing. The reason for the increased carrying capacity of a roller over that of a ball is due to the distribution of the load over a line of contact rather than at a point of contact. The roller bearing increases the number of such line contacts and therefore further distributes the load to the raceways. By increasing the number of line contacts, the cageless rollers reduce the stress per roller and failure due to fatigue. The fatigue factor is reduced 40 per cent, comparing a cageless with a caged roller.
1933-01-01
Technical Paper
330057
Ford L. Prescott
1932-01-01
Technical Paper
320049
D. P. Barnard
THE PAPER suggests a criterion for the tendency toward overheating of plain journal bearings of the high-speed type. The application of a criterion consisting of the product of oil viscosity by the square of the running speed is considered on a heat-balance basis and is compared with a series of observations of crankcase temperatures in a number of typical cars. Quoting the fact that in a plain journal bearing the coefficient of friction is a function of the term “viscosity times rate of sheer divided by unit load,” the author states the symbols and units employed and analyzes heat generation in the fluid film. An analysis of the dissipation of frictional heat is presented also, together with a discussion of the subject of bearing-temperature estimation. Curves are presented which resulted from data based on observations taken during a series of tests on a number of representative passenger-cars on the Indianapolis Speedway.
1932-01-01
Technical Paper
320058
H. C. Dickinson, O. C. Bridgeman
SATISFACTORY performance of a lubricant depends upon characteristics of the lubricant, operating conditions and design of the device in which the lubricant is used. Applied lubrication requires a study of the relation among these factors in their effect upon performance. The authors treat journal bearings, ball and roller bearings and gears. Equations are given for journal bearings operating under various conditions of design, lubrication, friction and heat dissipation. The authors conclude that neither ZN/P nor PV alone is adequate as a measure of the power dissipated by a bearing, a composite relation involving both terms being required over a large part of the operating range. They show that each bearing has a minimum value of ZN/P below which it may get into the unstable region of thin-film lubrication and fail.
1932-01-01
Technical Paper
320009
S. A. McKee, T. R. McKee
AUTOMOTIVE engineers, who have to deal with high-speed high-load journal bearings and are confronted with fear of the consequences of “ragged-edge” thin-film lubrication, will find much of interest and value in this report. It covers the information obtained and conclusions reached as a result of the extension of research into the region of thin-film lubrication, in which little investigation has heretofore been made. Tests made in a four-bearing machine, using both high-tin babbitt and high-lead bronze bearings and operated on lubricants of various viscosities over a wide range of speed and load, showed conclusively that the coefficient of friction depends directly upon the viscosity even in the thin-film region. They indicated defnitely that the friction coefficient is more likely a function of ZN/√P than of ZN/P.
1931-01-01
Technical Paper
310040
Ford L. Prescott, Roy B. Poole
FOR the rapid calculation of bearing loads in aircraft engines the authors have developed an analytical method that is described for the first time in the paper. This was derived from the long tedious graphical method that was formerly used and its accuracy is asserted to be sufficient for all purposes of engine design. Results of an analysis of the bearing loads in the Curtiss V-1570 Conqueror engine which were obtained by the graphical method are first presented in considerable detail. The Wright R-1750 Cyclone is next analyzed, the method that was employed not being as precise as that used for the other engine. An application of the analytical method using empirical constants derived from a graphical analysis of various engines is also presented. Numerous illustrations and tables supplement the text.
1931-01-01
Technical Paper
310007
A. T. Colwell
AFTER stating that increased speed, mean effective pressure and piston displacement of engines have made valve conditions more difficult during the last few years, the author recalls the path which development has followed by a brief list of materials and methods of cooling. Where the stem joins the head is the hottest part of the valve. A shield for this point is shown, also a shroud to protect the end of the valve-stem guide. Cooling the valve increases its life. Salt and sodium cooling are compared, and methods of sealing the coolant in place are described. The construction and behavior of copper-cooled valves are illustrated and recounted, and a one-piece hollow-head valve is described. Reasons for valve-seat inserts are given.
1929-01-01
Technical Paper
290043
A. B. Cox
1929-01-01
Technical Paper
290021
RICHARD E. BISSELL, GORDON T. WILLIAMS
DESIGN and the material used in the construction of automotive poppet valves, particularly exhaus valves, are discussed in connection with the necessity of resistance of the valves to physical and chemical actions of wide variety. The problem of resisting these actions lends itself to mechanical and metallurgical solution. Each part of the valve-the head, the stem, and the end and tip of the stem-is discussed separately; and the design of the head is considered as it relates to the upper or combustion-chamber surface, the edge, the seat and the lower or manifold-radius portion. Provisions made for the grinding-in of the valves are shown and described.
1928-01-01
Technical Paper
280062
CHARLES H. LOGUE, R. B. FEHR
BY means of the gear-correcting process described, spur and helical gears are corrected to give a high degree of uniformity in spacing and profile so that the gears become practically interchangeable. They acquire a “crown face” which enables them to run with unusual quietness under practical conditions. This is essentially an inspection-correction process, as it automatically finds and eliminates the errors. The lap is the important item in the process. It is of chilled cast-iron, gray cast-iron, or type metal, and is made by casting in a mold around a steel chill cut to approximate the gear to be corrected but has a face-width several times that of the gear. The lap, when completed, looks like a wide-faced internal gear.
1927-01-01
Technical Paper
270014
E. F. BEHNING
ACCORDING to the author, gear clatter and clash caused by metal-to-metal contact develops into an annoying whir or howl at high gear-speeds, and a material was sought that is flexible and resilient enough to absorb the vibrations or change their frequency to a pitch inaudible to the average human ear. Since vibrations in the crank, the cam and the generator shafts are transmitted to the timing-gears, which run at high speeds, a material was needed that would silence the consequent noise and provide a noiseless timing-gear train. A great variety of materials was investigated and the development of laminated, phenolic, condensation products resulted; these have proved mainly suitable for timing-gear-blank stock and stock for other gears such as those suitable for crankshafts and generator shafts. A further development was that of the flexible-web cam-gear made of the composition material.
1927-01-01
Technical Paper
270015
R. S. DRUMMOND
AFTER outlining the present status of the forms of drive for timing-gear trains, the author describes modifications of gear design made by the company he represents to overcome noise that involve lengthening gear-teeth for a given pitch. Various modifications in this regard were made and one having 16-pitch teeth with 12-pitch length had 10,000 miles of use in fourth speed without developing excessive wear. A further development resulting from experiments was the use of case-hardened timing-gears for motorcoach engines, such usage being thought to provide the most extreme conditions. Characteristics of so-called anti-stub gears are stated and predictions are made as to the future of timing-gear practice.
1927-01-01
Technical Paper
270056
H. S. KARTCHER
ONE of the standards adopted earliest by the Society is the list of taper fittings. This standard was adopted in 1914, and has been in use ever since with little revision. Saying that the indicated method of dimensioning and stating limits for taper fittings is not practical, at least in some cases, the author suggests various methods for expressing the tolerance in terms of the longitudinal position of a basic diameter. Another point brought out is that the sides of the keyway are not parallel to the taper. In the 2-in. size, for instance, if the bottom of the keyway is made parallel to the extreme element of the taper as it existed before cutting the keyway, the depth at the side is computed to be 0.0318 in. at the large end of the taper and 0.0392 in. at the small end, a variation of 0.0074 in. between the two ends.
1926-01-01
Technical Paper
260056
JOHN BETHUNE, W. G. HILDORF
Stating that the production of satisfactory gears is one of the most serious problems confronting the automobile builder, the authors give an outline of the practice of producing gears that is used by the company they represent and describe a new method for cutting the rear-axle drive-pinion by using two machines, each machine cutting one side of the teeth. Explanations are given of the various steps in the process and the reasons for stating that this method is not only cheaper but produces gears of higher quality. Numerous suggestions are made for improving gears and axles, and the claim is made that it is doubtful if the spiral-bevel gear has had a fair chance because axles usually have not been designed so that the main consideration was the requirements of the gears.
1926-01-01
Technical Paper
260042
L. R. BUCKENDALE
Progress in the development of automotive worm-gearing is interestingly outlined. Previously tO 1912, American experience had been limited almost exclusively to the industrial form, generally of the single-thread type. Introduction of the motor truck required a worm for the final-drive but one having entirely different characteristics from that of the industrial gear. Experience in designing these was lacking, however, as was also the special machinery to produce them. In 1913, machinery was imported from England and since that time development has been rapid. First efforts were devoted to simplifying the design of the axle as a whole, studying the problem of getting lubricant to the bearings, heat-treating the parts, and improving the materials of construction.
1926-01-01
Technical Paper
260044
C. H. Calkins
After a brief historical review of the development of worm-gears, the author deals with worms and worm-wheels in detail, presenting the subjects of proper choice of materials, tooth-shapes, worm-gear efficiency, the stresses imposed on worm-gearing and worm-gear axles. Usually, he says, the worm is made of case-hardened steel of S.A.E. No. 1020 grade; however, when the worm-diameter is smaller and the stresses are greater, nickel-steels such as S.A.E. Nos. 2315 and 2320 grades are utilized. The worm should be properly heat-treated and carbonized to produce a glass-hard surface. Grinding of the worm-thread is necessary to remove distortions. Bronze is the only material of which the author knows that will enable the worm-wheel to withstand the high stresses imposed by motor-vehicle axles, and three typical bronze alloys are in common use.
1926-01-01
Technical Paper
260041
ARTHUR L. STEWART, ERNEST WILDHABER
After defining hypoid-gears and outlining their action, together with their general characteristics and advantages, the authors compare them specifically with spiral-bevel gears and follow this with a description of how the axis of the pinion is offset from the axis of the gear and how the direction of the offset determines whether the spiral is right-handed or left-handed. Considering pitch-lines, details of the mesh between a crown-gear and an offset pinion are presented, since this constitutes a special case of hypoid-gearing, and the application of these principles to a pair consisting of a pinion and a tapered gear is discussed. The rate of endwise sliding, the proper ratio of gear-diameters, tooth loads and tooth profiles are other phases treated specifically, and computations of surface stresses by the Hertz formulas, with special reference first to a comparison between helical teeth and straight teeth, and then with reference to hypoid-gears, are outlined.
1926-01-01
Technical Paper
260008
D P BARNARD
Surfaces that slide upon one another can be lubricated by one of two mechanisms, (a) heavily loaded surfaces working at low speed depending upon the oiliness of the lubricant and (b) high-speed bearings depending upon its viscosity. In the latter, conditions must be adjusted so that an adequate supply of lubricant will be provided and an opportunity given for it to be trapped between the surfaces and actually to wedge them apart. The bearing must therefore have a certain clearance over the journal. Oil-grooves must supply means for the oil to enter the bearing and the assurance that it cannot escape without doing its work. In general, they should not be placed on the loaded side of the bearing. The tendency is to draw the oil from the point of minimum pressure through that at which the pressure is the maximum, and for the oil to spread out and travel in a spiral along the bearing toward the ends.
1926-01-01
Technical Paper
260005
ALBERT LE ROY TAYLOR
Tests made to ascertain the degree of crankcase-oil dilution beyond which it is unsafe to run an engine bearing are described and the data obtained are analyzed, the details of the apparatus used being specified. To study the effect of dilution only, new oil was used in each case and was diluted to the desired extent by adding to it the proper quantity of diluent; that is, samples of oil obtained from engine crankcases were distilled by heating, and the distillates were used to dilute the new oil. The apparatus used for distilling the crankcase oil was an ordinary glass still, which was operated in conformity with standard methods. Four lines of investigation were followed in making the tests, these being outlined. In general, the results of the tests indicate that dilution of the oil up to 50 per cent has no bad effect upon the engine as regards increased friction and temperature of the bearings, although the dilution may be injurious from other standpoints.
1925-01-01
Technical Paper
250057
PERRY L TENNEY
Periodically recurring problems of gear noise and wear which seem to arise from no specific cause frequently affect the manufacturing side of the automotive industry and especially the gear-manufacturers. While much has been written and discussed about the mathematics and geometry of gears, which should overcome all of these problems, the trouble unfortunately still persists. The paper outlines the experience of the organization with which the author is connected in solving a rather difficult problem that offered an opportunity for a more thorough analysis than did its predecessors. Laboratory and dynamometer analyses of the product showed that it compared favorably with the output, of other factories.
1924-01-01
Technical Paper
240018
L A DANSE
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.
1924-01-01
Technical Paper
240014
F F CHANDLER
Lack of scientific research is specified by the author as being the cause of failure to develop steering-systems generaly to meet the present need for better and easier steering-ability. He comments upon the meager data available regarding steering-system faults and factors that influence design and emphasizes the necessity for determining the live stresses in steering-systems while the vehicle is traveling over roads of all kinds, so that designs can be made with greater confidence and greater safety attained. Defining comfort as being inclusive of easy steering, a comfortable sitting position, convenient location of the controls that must be handled frequently and peace of mind relative to steering accuracy and dependability, he analyzes the causes of hard steering, saying that the steering-system includes every part from the steering wheel through the steering-gear and linkage to the front wheels and that the steering-gear itself is simply the reduction mechanism. Assisted by H.
1923-01-01
Technical Paper
230020
S O BJORNBERG
Detroit Section Paper - Since a gear is a product of the cutting tool, the gear-cutting machine and the operator, it can be no more accurate than the combined accuracy of these fundamental factors. All gear manufacturers aim to eliminate split bearings, high and low bearings, flats and other inaccuracies in tooth contour, because a gear having teeth the contours of which comply with the geometrical laws underlying its construction is by far the most satisfactory. Illustrations are presented to convey an understanding of the geometrical principles involved, together with other illustrations of testing instruments and comments thereon. The application of these instruments is termed quality control, which is discussed in some detail under the headings of hob control, machine control and gear control.
1922-01-01
Technical Paper
220008
ROBERT E WILSON, DANIEL P BARNARD
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.
1922-01-01
Technical Paper
220056
K L HERRMANN
The different gear noises are classified under the names of knock, rattle, growl, hum and sing, and these are discussed at some length, examples of defects that cause noise being given and a device for checking tooth spacing being illustrated and described. An instrument for analyzing tooth-forms that produce these different noises is illustrated and described. Causes of the errors in gears may be in the hardening process, in the cutting machines or in the cutters. A hobbing machine is used as an example and its possibilities for error are commented upon. Tooth-forms are illustrated and treated briefly, and the hardening of gears and the grinding of gear-tooth forms are given similar attention.
1922-01-01
Technical Paper
220058
JAMES A FORD
The process devised by the author was evolved to eliminate the difficulties incident to the finishing of the spline and body portions of a spline shaft, such as is used in transmission gearing, by grinding after the shaft has been hardened, and is the result of a series of experiments. The accuracy of the finished shaft was the primary consideration and three other groups of important considerations are stated, as well as four specific difficulties that were expected to appear upon departure from former practice. Illustrations are presented to show the tools used, and the method of using them is commented upon step by step. The shaft can be straightened to within 0.005 in. per ft. of being out of parallel with the true axis of the shaft, after the shaft has been hardened, and it is then re-centered true with the spline portion.
1921-01-01
Technical Paper
210013
WILLIAM T MAGRUDER
The time has come when greater attention must be given to the smaller parts and the various appliances found on automotive machinery. Previously, investigations have been made by the research laboratories of a few companies manufacturing engines, carbureters and some other parts, but chiefly engines; by the laboratories of research corporations, including the Bureau of Standards and the Bureau of Mines; and by the engineering laboratories of colleges and technical schools. The number and value of the researches that can be conducted and reported on from time to time by these agencies depend entirely upon the appropriations that they can obtain by act of legislation and upon the personnel of the staff that can be attracted by the opportunity to do this class of work.
1919-01-01
Technical Paper
190055
F C GOLDSMITH
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