‘ ll HHIWIIIHIIHIIJ | l 4 l —| _. In in (D\l—b POURNAL TYPE BEARINGS FOR J ELECTRIC MOTORS THEIR DESIGN, CONSTRUCTEON. AND LUBRICATIQN ‘ I Thesis for the Degree of M. E. Fred M. Hill ' 1935 a Yawn 11:6.‘1 I , , 3/ /_n_1/_‘/I JOURNAL TYPE BEARINGS FOR ELECTRIC MOTORS THEIR DESIGN . GONSTRUGTIQI, AND LUBRICLTIm Thul- ror Dogma of LE. had I. Hill 1935 SSSSSSS VII. TABLE 0'! CONTENTS INTRODUCTION 0 o . . o o . o . o . HISTORICAL o o . . . . . . . . . m ELECTRIC MOTOR AND ITS HEARINGS o o . MORETICAL ASPECTS OF DESIQW . o . o . PERFECT AND IMPERFEOT CONDITIQWS OF LUBRICLTION most-Ion. commmnons m BEARING DESIGN . LUBRICANTS um LUBRICATING nmxcnmcy . . nwmmummnmcnunmmmmzuammms. momma. Emma DESIGNS . . . . . . mmmmmummma. . .. . .. . . mummrmmmmmmnmmmm .. . .. 'nmmmormmmms . .. . .. . . zmmrmmmm . .. . .. . .. . mmmnmmn. . .. . .. . .. . AHEMU(HHWEA®IMMW). . .. . 98888 15 16 18 21 23 I. WU The ail of the author in preparing this thesis is to colpile infornation gained fr. research and fron personal experience that will assist the executive, engineer, designer, nachinist, and the naintenance nan in solving problens of both a technical and practical nature. A brief historical outline is included to broaden ene's concept of the sub- ject and to provide an interesting background. a censiderable nunber of tabulatins, diagrans, drawings, and photographs are used to illustrate various principles and facts and to guide one in the solution of everyday problem. A subject of this nature cannot be covered by a few sinple statenents. To cover the subject in its entirety would be an endless task. here is a wealth of theoretical infernation available in techni- cal publioations, particularly of recent years. Engineering text books give brief and fundamental principles. Ian handbooks give valuable tables and empirical formula principally for the designer. There ap- pears to be a decided need of correlatiu between the two, especially in the fern of a single treatise. It is hoped that this work will be of value in fulfilling this need. in references will be given to fern a basic network of the subject. the author's personal experiences and observatius are given with the thought that they ny prove of cone worth in formlating nere accurate conceptions. Acknowledgnent is hereby given the consumers Power Onpany of Iichigan for the opportunities presented the author. During the period of four and one-half years, over 16,000 industrial netore were changed over fro. so to so cycle service. my problens involving bear- ings and their lubrication naturally occurred, from which the author was privileged to gain first-hand experience. this experience has been a valuable aid in formlating the text of this work. 11. Mlfl Ancient nachinery consisted of sinple pulleys, windlasses. carts, and sleds roughly nde fra wood, and if lubricated at all, were packed with anilal fat or tone-1. m chariot found in the lgyptian tab of Iona and min about 1400 3.0. still had none of the original lubricant on the axle. Lucas, the Official Cheniet ef the Cairo maeun, analysed the lubricant and indicated it to be either a mtton or beef tallow, either one of which would have been suitable in such a warn cli- ‘tOe 0n the inner wall ef the lgyptian tonb bhuti-Betep appears a decoration inscribed about the tins of Joseph, 1660 3.0.. showing the nethcd of lubrication enployed in mving the great stone statues? his appears to be the earliest historical record of the use of a lubricant. the lgyprtians had available nearly every aninel oil and fat, as well as at least thirteen vegetable oils of our tine which were used for food and for the arts. here of flounder wrote about 150 3.0.. illustrated and de- scribed a fire pulp with bronze cylinders bored in a lathe and equipped with pistons and rods which were *rubbed with oil' according to a later writer. as oil was undoubtedly aninal or vegetable. no nnufaeture of petroleun was indicated by Herodotus, see-424 3.6.. but its general use does not appear until Dr. Janos Young in 1847 found petroleun in Derbyshire, hgland, fr. which he obtained a heavy lubricating oil by destructive distillatiu. In 1763, James I’att becane interested in the stean engine and along other things perfected a device for feeding ulted tallov to the piston and cylinder walls. tor over half a century tallows were used for this service. About the year 1N0. or shortly before, there was a general reawakening of nechanice and the use of nachinery. In naohine shops lard oil was the universal lubricant. Bpern oil held supremacy for lub- ricating light high speed nechanisns. rcr heavy machinery, beef and mtton tallows were found not suitable. At tiles chunks of pickled side pork with the hide and hair left on were found to be satisfactory. he author finds that there are still non living who used strips of pork rind with flax yarn in packing piston rods of water punps, as late as thirty years ago. In 1810. Ora-e was given credit of producing the first on- nercial electrical nachine for continuous operation. By the year ices electrical nohines were being rapidly developed and the use of nineral oil was quite general. In 1886, Osborne Reynolds established the fast nathonatically that a well-lubricated journal rotating at a fair speed becones autcnntically separated fru its bearing by a fill of oil under pressure and that the functional resistance is then due entirely to the viscosity of the on? ' III. mmcmmmmnms lll'he electric notor today, sons forty years after its intro- ducti- to industry, occupies a preeninent place anong power drives. It has virtually supplanted all other devices except the gasoline and the steen engine in rencte instances. his is due to several reasons, chief of which are its versatility, sinplicity, dependability, and low naintenenee cost. It also possesses good speed regulation character- istics, occupies little space, and its energy supply is conparatively sinple. Bovovor simple and reliable it ney be, it is not without its faults. Like all nechinery it is subject to wear and the consequent depreciation. no quality of nterials and worknsnship is often quite variable, as well as the latter of designs. In exanining the photo- graphs in the appendix one will note in particular the wide variance in oil grooving. he proportions of length to width and other details of construction show a decided lack of standardization. In the desiu ef ntor bearings there are certain fundanentel requirements that cannot be fulfilled in the ideal nanner. a nunber of conpruises met be nade. there is a decided gap between eptimn conditions and actual running conditions. Laws governing optimum.con- ditions do, however, serve as a guide or reference standard and aid ones conception of the hydrodynamdc action taking place. Empirical formulas are very useful and fer all practical purposes are sufficient. in under- standing of the theory of lubrication is oftentimes a very valuable aid in solving bearing and lubrication problems. IV. turmoil. ASPECTS OF DEIGN There are several most excellent articles covering the mthe- ntieal analysis of the bydrodynanic theory of lubrication. They can easily be found in our public libraries and will, therefore, be omitted here because of their great length. References to them, however, will be node and a rather complete list will be found in the appendix. A very complete mathematical analysis will be found in 1.8.16.3. Trans- actions develOpod by cirdunot By the use of differential and integral equations he arrives at certain formulas of fundamental significance. His work is rocomsnded where a very thorough analytical concept is sought. The first real explanation of the fact that oil is able to in- sinuate itself between the rubbing surfaces of a journal and its bearing while carrying a heavy load, is accredited to Reynolds? However, Reynola assumed the bearing to be of infinite width. In actual practice there is considerable side leakage. llichell developed the theory and solved the problem for finite width. nngsbury has written several articles of a highly technical nature covering both the bearing of infinite width and of finite width? 7 In order to simplify the integration of nathematical formlas, Kings- bury resorted to an electrical integration method. The nest recent de- velopnent along this line comes from Needs, of the n sbury lachine Iorks, who also used the electrical integration nethod. lteeds lays particular emphasis on the effect of side leakage. His article is par- ticularly valuable for the design of large turbine and generator bear- ings where nechanical construction and operating conditions more nearly approach the optimal. for graphical stadies of journal bearings, Howarth has lads valuable contributions. Karelitx also shows bearing perfornances in graphical ferns}D One of the nest outstanding articles of a nore practical nature was nde by Hersey} Hersey's work gives nioh experinental data fron which empirical formlas are derived. One of the nest ingenious methods of obtaining actual pres- sure distributions was devised by lone-Ilene of the Bureau of Stand- ards}: Their charts will be very useful in pointing out certain fea- tures in the construction and operation of electric notor bearings. Two sets have been photographed and are shown as rigs. l and 8. Ref- erence will be node to then subsequently. 7. mar AND WOT ngTImS OF LUBRIGLTIW l[he foregoing references are all based on the asounpticn that the rubbing surfaces are completely separated by a fill of oil. Such i is not always the case, however, in practice. Because of misalignment, improper oil grooves, adverse loadings, inadequate supply of lubricant, and other conditions, there may be a partial mstal-to-metal rubbing. Of course during starting and stepping there will always be metallic contact. The author has mde tests on motors in operation using an electric circuit with ball elem and has found the surfaces to be en- tirely separated by a film of oil even under heavy belt pulls. The tests were made on motors with hearings in good condition. The author has concluded that the bearing and journal of the modern electric motor, when constructed in accordance with scientific principles, does give re- sults agreeing closely with conceptions of perfect lubrication. Investigations have been ends by McKee-McKee to determine frictional characteristics with loads sufficient to cause ruptureit‘I The loadings used were many times greater than those imposed on an elec- tric motor, being on the order of several thousand pounds per eq.in. of projected area. While it is possible to carry tremendous loads on a journal bearing under favorable conditions, it is advisable to use values somewhat under 100 lb. for electric motors. VI. PRACTICAL CWSIDERATIONS IN BELRIM DESIGI The oil is supplied to the bearing by means of the conven- tional oil ring in motors ranging from about one horse power upward. Above about 25 horse power, two rings are generally employed. Built-in type motors, those whose bearings are in reality a part of the driven nchino, may be lubricated in a number of different ways. Those driving large air and ammonia compressors will ordinarily be of the forced food type. Fractional horse power motors are almost universally oiled by means of a felt or wool pad, or wick. The, quantity of oil required by these small motors comes well within the capacity of the wick. One ad'- vantage of wick oiling is that the motor can be operated in almost any position. Vick-packed bearings have proved to be entirely satisfactory in practice. Karelitz has investigated the performance of waste-packed bearings and his publicationmshould be of value to the designer. Ring- oiled motors mat, of course, within close limits be operated in a given position and with the shaft horizontal. Many designs of rings have been tried in an effort to increase the oil delivery. rig. 3 shows six types of rings and their cross soctims, four of which are in general use. They are ordinarily nde of brass or bronze; however, one will occasionally find rings mde of compositions resembling babbitt. Type (e) is made from two narrow conical-shaped washers of steel tack welded together. Types (a), (b), and (o) are com- monly used; (c), seldom; and (d) and (f), rarely. (a) and (c) are uni- versally used where jointing is necessary as in split type bearings. So far as the author is aware, no tests have been made to determine the oil delivery capacity of variously shapsd rings. The performance of oil ring bearings has been investigated, howe'verlv6 Ihile ring oiling my not pro- vide as copious a flow as some other methods, experience has shown it to b. ample e Once the lubricant has been supplied to the rubbing urfaces, the hdrodynamic action is depended upon to support the load. It is not at all rare to find mtcrs that have been in operation for twenty years or more without bearing repairs. m the other hand, bearings have been known to fail after only a few hours of service. Bearing troubles and remedies will be discussed later. VII. MCI!!! AID 1211331012130 mouse! The lubricant almet universally used for motor bearings is o petroleum oil having a viscosity of 136.140 Universal Seybolt at 106’ I. If absolute viscositiee are known or determined from calcula- tion, they can be converted to eomaercial viscositiee by the use of rig. d which also gives relations between the various censorcial systems. The oil should be well refined, free from suspended matter, water, acid, and vegetable or animal oils. ' Ior low temperature operation, an oil having a viscosity of 105-110 Saybolt at 100° 1'. and a cold test of ~20” r. is better suited. Icr the unusually high temperatures, a viscosity of 160.165 is mro nearly correct. Practical knowledge and good judgment must be used at times when unusual conditions of operation prevail. In general the three grades just given will be adequate for temperature ranges fr. do" to 120° 1. necrotically for maximum lubrication efficiency there is a certain film thickness which is dependent upon temperature of the film, the operating viscosity, the rubbing speed, bearing clearance, and width of bearing. Obviously it is impracticable to nintain ‘21- mm efficiency. An experienced person can, however, judge the oper- ating viscosity by observing the action of the ring and oil. If the action is sluggish, due to the oil retarding the ring, then a lighter bodied oil should be used. If the action is lively, but the lubricant appears watery, a heavier oil is required. There is a very important physical characteristic of mineral oils that should not be overlooked; namely, the difference in the rate of change of viscosity for given temperature changes. in asphalt be e oil may have a viscosity twice as high as a paraffin base oil at 100 ., but when compared at a temperature of 150° 1., they will be approxi- mately the some value. Let us now consider a number of conditions affecting the ef- ficiency of lubrication. There not be reasonable tolerances in the diameters of the journal and bearing bore. Table I shows those used by one of the leading manufacturers of electrical machinery? Ihon the maximum clearances shown in the table have become doubled due to wear, the author considers new bearings to be necessary if good operating conditions are to be maintained. The accuracy of alignment of the bearings with the journal is oftentimes very imperfect in practice due to errors of Inchining and methods of manufacture. he error of mis- alignment is for the most part overcon in large motors by the use of self-aligning bearings. misalignment causes concentration of bearing pressures and results in undue wear of the rubbing mlrfaccs. The finish of the rubbing mlrfaces as left by the manufacturer is ordinarily good enough; however, grit in the hearing may leave the surfaces in such a roughened condition as to greatly impair the bearing efficiency. 11g. 8 shows a bearing and journal whose surfaces are in good condition. fig. 0 shows the journal after grit had damgcd the bearing. rig. 7 shows a babbitt-lincd bearing after scoring due to grit. fig. 8 is a journal that has been badly pitted due to electric currents. fig. 9 shows a very bad case of electrical pitting of a bearing. fig. 10 shows a journal and its bearing that have become danged due to clipping of the oil ring. rig. ll shows a bearing whose efficiency is greatly reduced by very bad oil grooving and electrical pitting. nose cases just cited are for the most part extreme examples, but they are introduced here to show what one actually finds in practice. They will be discussed more in detail later on. The oil ring my perform badly due to being rough or out of round. fig. 18 is a photograph of an oil ring taken from a large bearing showing the effect of dancing. which is detrimental to good oil delivery. In addition to the above mentioned causes of poor efficiency, the author has found in bearing housings large quantities of such foreign matter as bronze or babbitt particles resulting from wear, dirt from the atmosphere and surrounding objects, water,mwdust, flour, etc. Ihile lin- seed oil may not be considered a foreign matter, the author has actually fbund bearings in which this oil was used. It is not at all remarkable that ntcr bearings oftentimes run poorly but that they run at all. As previously stated, a good mtor lubricant should be a well- refined mineral oil, free from suspended utter, water, acid, vegetable oils, and animal oils. By suspended matter is meant, foreign substances as dirt and particularly grit. later and acids cause rusting or otherwise attack the metallic rubbing surfaces. Vegetable and animal oils turn ran- eid, thereby causing guaming and the formation of free fatty acids. A most excellent book for one interested in making tests of lgbricating oil is written by Bottle and is obtainable in public librariool.‘ VIII. 3% mouse W W CAPACITIES he ability of a bearing to carry loads depends upon ten gen- eralinod principles, sons of which have already been touched upon. These principles have been laid down by such prominent men as Tower, Thurston, Goodman, Lasehe, and Stribeck Bicrbaum has organised these principles and tabulated them as follows 1. The bearing surfaces are completely separated by a sup- porting film cf oil. . 8. The friction of operation is the fluid friction in the oil film, and adequate thickness of film is essential. 3. During construction, proper clearance or space should be provided for a normal thickness of oil film. 4. he advance edge of a bearing surface must be rounded or chamfered off in order to permit a supporting film of oil to form. 8. the oil film- forms most effectively upon a bearing surface whose advance edge is at right angles to the direction of mtion. c. in increase in speed increases the thickness of film, all other conditions renining constant and clearance 7. in increase in the viscosity of the oil increases the thickness of the film, all other conditions remaining constant and clearance permitting. 8. in. larger the unbroken film of oil, the greater will be the average pressure supporting capacity per unit area, other conditions renining constant. 9. Ivory unnecessary oil groove or interruption in the continuity of the oil film reduces the supporting ca- pacity of the film. 10. for every bearing condition there is a film thickness corresponding to maximm lubricating efficiency. It will be seen from this tabulation that load carrying abil- ity is effected principally by four conditions; namely, rubbing speed, viscosity of lubricant, film thickness, and area of unbroken oil film. or these four conditions the viscosity of the lubricant and the film thickness have already been decided upon for electric motor operation. In the matter of actually measuring the bearing clearance, the author has found the lead wire method to be the most reliable and most exped- ient. Fig. 13 shows a large bearing with a lead wire at the right be- fore squeezing, and at the left after squeezing. By measuring the flattened wire, the onset clearance is determined. By this method the bearing and journal need not be removed from the motor. The bearing, of course, not be of the split type when this method is used. Due to irregularities of the rubbing surfaces, measuring the bore and journal diameters separately with micrometers may prove laborious as well as misleading. . Perhaps the greatest contributing cause to poor lubrication in electric meter bearings is found in the use of improper oil grooves. considerable attention has been given this matter by the author who has had a great nmy bearing troubles to investigate. rigs. 14 to :8 incl. are photographs taken to show the various oil grooving systems actually found in practice. The most elaborate grooving is shown in Fig. 11. Io have here a display of almost every conceivable oil groove, good and bad. No attempt will be made here to analyse the effects of each and every type shosn. It is doubtful if such an analysis would prove more than the fact that most of them are bad. It is apparent that there is a very decided need for a better understanding of the principles of lub- rication among those responsible for design and construction. 11g. 28 shows two die-cast bearings whose oil grooving conforms to correct prin- ciples. Pig. 8’ shows the type adopted by the Prequency Change Depart- ment of the Consumers Power Company after a thorough study had been made of oil grooving systems. This type of bearing has proven satisfactory whore severe loading conditions caused other bearings with bad grooves to fail. l'his bearing can be made in an ordinary lathe and does not re- quire any special equipment other than a boring bar with suitably shaped end for cutting the longitudinal distributing grooves. In order to show the effects of oil grooves running through pressure areas of the oil film, rig. 30 has been constructed using lines of equal. pressure similar to those shosn in Pig. 1 (o) and Pig. I (c). It might be explained here that the difference in the pressure distri- bution lines between the two diagrams is caused by differences in clear- ance, speed, and viscosity. large clearances and slow speeds cause localized distributions with elliptically shaped pressure lines, small negative pressure areas, and high maxim pressures. High speeds and small clearances give more extensive areas with lines that tend to be- come rectangular, large negative procure areas, and lower maximum pressures. It will be noted that the so-called “generalized operating variablo' 3/1? is nearly equal in both cases. In this expression 2 e absolute viscosity, l - revolutions per minute, and P 8 unit pressure. this expression is somewhat of a criterion for bearing design that has come into use in the last few years. Previously, the equation P! I c was generally accepted as expressing the carrying capacity of a bearing. In this formula V ! velocity of rubbing surfaces, and c 8 a constant. In the author's opinion, neither of these are sufficient to express the perfonance of a bearing, nor are they sufficiently inclusive for a logical design. lurning'new to rig. so, suppose an oil groove were cut cir- cumferentially from A to B, as shown dotted in (A), pressures would then drop to core on each side of the groove throughout its length re- sulting in a very great loss in load-carrying capacity. If curve I, in (B), represents the average axial pressure distribution before cut- ting the groove, and curves P and G after, then the shaded area repre- sents the loss in capacity. be hearing then becomes equal to two narrow bearings of half width. Sappose now that a groove is cut across the bearing from c to D instead, if curve B, in (0), represents the distribution of the average circumferential pressures before cutting the groove, and curves 1 and I after, then the difference in area under H and the sum of areas under I and I represent the loss in capacity. The difference obviously is very great and is represented by the shaded area I. Such a bearing as shovn in Pig. 11 would have pressure distri- butions that are cnaponents of (B) and (0) in Pig. 30. remltimg in very poor bearing efficiency in general. as ”edges of the grooves in Pig.ll are extremely sharp and naturally they act as scrapers.to remove the oil fru, instead of aiding its delivery to the rubbing surfaces. Pven with the most favorable design of oil grooving as in Pig. :9, it is possible to have adverse conditions especially when the journal thrust is against one of the horizontal distributing grooves and the rotation of the journal is such that oil delivery is toward this groove. his condition is indicated in Pig. 31 although the journal is shown central. Better lubricating conditions would be had if for a journal thrust shown the rotation of the shaft were left hand instead of right. Oil would then enter where the clearance is nearly a maxim. It is desirable to have the distributing grooves terminate a short distance before the drain grooves are reached to avoid direct loss of oil to the housing or well. the drain grooves should be cut close to the end of the bearing in order to give the nxinlm effective area for the lubricant. In calculations involving projected area, the width of the bearing should be considered as the width betveen grooves and not from and to end of the bearing. In solid type bearings the distri- buting grooves can be carried well above the center of the bearing as shown in Pig. 81 and thus be more effective against horizontal journal Imitlo II. ”WWW Having described operating conditions both good and bad, the question arises how best to arrive at a rational design. Solutions by higher mathentics are of little direct value. at best they serve as a guide only. hpirical formulas, if well chosen, are mifficient. the author has selected fornilas based upon experimental data and has drawn curves by which one can readily solve for load-carrying capacity and for operating film temperatures both of shich are limiting factors. If the ratio of the width of the bearing to the diameter of the journal is kept approximately three to one, and standard initial clearances as shown in Table I are employed, the design will come sell within the limits of good practice. It is presumed that the shaft has already been designed for sufficient strength and rigidity. hero is also the utter of critical speed to be investigated. Pig. 32 is included in the appendix for this purpose. It is self-explanatory and needs no explanation here except to say that the operatingmspeod should be hept from 15 to not above or below the critical speed. Phe- fonulas selected for bearing loadings are based on tests made by Alford whose work stands undisputed and is often quoted as authoritative The curve, Pig. 3!, was constructed from three fernlas after changing slightly the constants of two of them in order to ‘h a smooth continuous curve. the changes do were 7 to 7.85 in the fur-clai- 7T7and 30 to 89.d in!‘ 30 Y . the curve hasa factor 10 of safety of two. The critical breakdosn values are twice those shown. By selecting factors of safety to suit operating conditions, the unit bearing load is readily obtained. It is understood that the General llectric Company uses these for-Alas in their designs} be next step is that of determining the temperature rise or the temperature of the oil film. Kimball a Barr gives two very useful formulas for the generation of heat, which are as follows: Por speeds up to 500 ft. per minute u“ I 8.3 '1.” e e e e o e o o o (1, t 9 32 Per speeds above 500 ft. per minute ufl . 51.3 V e e o o e e e o e (2) t - 38 in which u 8 coefficient of friction v 3 pounds per sq.in. prej. area 7 8 rubbing speed in ft. per minute t e temperature in degrees P. of oil film The quantity qu represents the heat generated in foot pounds per minute per sq.in. of prej. area. Prom page 120 of the same source we find curves giving the heat radiated from various types of bearings except that no mention is specifically made of electrical motor bearings. Leutweilerugives x - 1150 for General Ilectric well-ventilated bearings in the for-11a Q Q (to § 33): o o o e e o e o o (3) I in which Q I radiation in ft.lbs. per second per sq.in. prej. area f. I difference in temp. between the bearing and cooling medium Pig. 8 shows the curves reproduced but with slightly different termi- nology to correspond with this text. Curve 4. was constructed from for-11a (3) in which I m 1150. Pquating the heat generation formulas (l) and (8) respectively to the heat dissipation for-nae, we get for speeds up to 509 ft. per min. 60 3M. (r°+”)z e o e e e e e e (‘) t-SI I and for speeds greater than 500 ft. per minute .0 , ci.av _, (r, . as)” t'33- x o e e e o e e e (5) Letting r. m t - tr in which tr 8 run temp., and letting I I 1150, formilas (d) and (5) become for speeds up to 500 ft. per minute 60 (t- +53” s.3v1’5 + 3 W e ._ e o e o (6) for speeds above 500 ft. per minute M.M.......m 1150 *-33 It is a very conch belief that the load carried by a bearing determines the heating. to the contrary, it has been proven that in perfectly lubricated bearings the generation of heat varies with the speed of rubbing. his significant fact is due to the reduction of the coefficient of friction with increase in load such that for a given velocity of rubbing the product of the coefficient of friction and'the unit load is constant. no running temperature of a bearing depends upon the quantity of heat generated and the quantity radiated. Obviously the temperature of the rubbing surfaces will reach an equilibrium when the rate of heat generation is equal to the rate of dissipation. The generation of heat in a journal bearing is a function of the viscosity of the lubricant. In checking over the experimental data from which for-nae (1) and (2) were derived, the viscositiee were found to check closely with oil specifications given on page 5, so that the for-alas have a direct application to electric motor bearings. 'i'here appears to be no appreciable difference in the radiating surfaces of General Electric motors and those of other mufaeturers in the same sizes. Therefore, curve 4 of Pig. 34 can be rearded as repre- sentative for electric motors generally. lquations (l) and (2) together with the curves of Pig. 34 can be used to solve problems involving bearing temperatures for electric motors, as well as for other types of journal bearings, but the process is one of cut and try. Pquations (d) and (7) for electric motors only are difficult of direct mathematical solution. The author has constructed the curves of Pig. 35 by using equations (6) and (7) which greatly simplify the work. Having given the rubbing speed and the room tenperature, the corresponding oil film 18 temperature is at once determined. It the film temperature is over 140° P., artificial cooling should be considered. Increasing the turbu- lence of the air around the bearing by adding fan capacity to the rotor my be sufficient. Occasionally a vertical bearing of the journal type is en- countered. in. same general laws govern the design of this type also. In order to distribute the oil to the rubbing surfaces, it is con-on practice to cut a spiral groove in the journal in such a direction as to elevate the oil. Such motors are therefore unidirectional. Pig. 36 shows a vertical bearing of a grinding nachine which happens to be belt driven. there is little difference, if any, between this bearing and the one used when the pulley is replaced by an electric motor. the clearance of this bearing is regulated by raising or lowering the bronze bushing. It is very important that the operator of this machine be thoroughly familiar with its construction. If the bushing is too loose, oil will run out of the bearing at the lower end. If too tight, severe damage my be done by overheating and seizing of the rubbing surfaces. W in. question often arises whether bearings should be babbitt or bronze lined. it first thought it would seem advisable to use a mterial that would not allow the rotor to come in contact with the bore of the stator in case of failure. in. writer has known of a large number of motors whose babbitt bearings have been overheated or other- wise mrn so that mbbing of the rotor took place. In no instance was there any appreciable damage done. in. meters simply becane overloaded and blow their fuses or they would refuse to start. If the bearings gradually went don, some evidence of overheating of the stator or on.- due noises gave sufficient warning. Bronze bearings due to their higher melting point do not fail quickly. hidence of failure usually shows itself by overheating or by mixing to the shaft and stopping the motor. It is frequently found that the shaft has been scored badly, a result that is seldom found with bob. bitt unless abrasive material is present. In so far as lubrication is concerned there is no appreciable advantage in either babbitt or bronze if the bearing is properly de-’ signed and lubricated so that the load is carried hydrodynamically. Generally speaking, bearings under two inches in diameter are mde of bronze while those over that size are node of babbitt. Babbitt re- quires a steel or iron supporting shell and is, therefore, impracticable in the smller sizes. Bronze sleeves require no extra support, but the quantity of mtal necessary in the large sizes mkes them too costly. here are a great mny varieties of babbitt metals on the mrket. The choice of a suitable grade becomes rather perplexing if the advertised claims for each brand are taken seriously. the most valuable . guide found is chem in Table II which was taken from an 13 L.S.T.M. publication? The range is sufficient to cover all practical purposes. The table gives all the physical properties necessary to characterize each kind, provided the babbitt has not been overheated and is poured at the correct temperature. The range extends from high tin base alloys to those of high load. The dividing line between the tin base and lead base babbitts is between Bo. 5 and No. 6. It will be noted that there is a decided changing over from a preponderance of tin to that of lead at this point. The antimony content remains virtually constant for alloys below No. 3. The physical properties for alloy No. 3 have the highest values almost throughout the entire range. Because of the high percentage of tin in this alloy, it must, of course, be comparatively expensive. It is under- stood that this alloy is the same as General Electric Company's babbitt No. 17. Phere extreme conditions of service prevail, alloy No. 3 should give excellent service; however, there are lead base alloys which are perfectly suitable for services where resistance to shock, toohigh tem- peratures, and to) high unit loads are not limiting conditions. Alloy lo. 3 is particularly suitable for airplanes and automobiles where bear- ing loadings may run as high as 3000 lbs. per .q.in.? where operating temperatures are high, and where a high degree of toughness is required to resist shock. It is a very good alloy for electric motor service, but a less expensive alloy such as No. 5 or No. 6 should prove entirely suitable considering the fact that loadings seldom exceed 100 lbs. per sq.1n. Icetinghousez‘has two grades of babbitts for electrical ma- chinery. Their alloy No. 25 is of the lead base type while their No. 14 has a tin base. Their general catalog states that their lead base alloy has been used successfully for many years in the manufacture of motors, generators, turbines, and other electrical equipment. They recomend their tin base alloy for excessive pressure, vibration, high speed, and heavy duty. Pig. 3'! reproduced from Westinghouse instruction book shows that a lead base babbitt my be superior to certain tin base babbitts in resisting impact loads. This is very interesting because a tin base alloy is ordinarily considered to be superior. Another sourceashows that the addition of lead in amounts of l, 3, and 3‘ to a tin base bab- bitt actually increased the hardness over a temperature range of 33° C. to 80° C. It is also shown that a lead base babbitt my be superior to a tin base babbitt over the same temperature range and may closely ap- proach alloy No. 3 in Table 11. These facts show that a lead base alloy can be mde that will compare favorably or even be superior to some of the tin base babbitts which are more expensive. The question arises that if a lead base alloy has suitable physical qualities and only costs from 80 to 30$ that of the tin base, why is it not universally accepted as the standard for use in electric motors. The answer, so far as the author can find, is because the lead base alloys my be greatly damaged by improper temperature control 14 during the pouring of the bearing while the tin base babbitts are gen- erally much less effected. This characteristic is clearly illustrated in Fig. 38. The proper temperature for pouring babbitts is shown in Tfibl. IIe To avoid overheating babbitts, close temperature control is essential. Ihether of the lead base or tin base, they should not be heated over 490° C. at any time. The time honored use of the pine stick in hands of experienced and competent workmen to test preper pour- ing temperature may be a fair substitute for electrically controlled pots, but if any quantity of work is done of any importance, pyrometer control is necessary. The author has repeatedly observed babbitt heated in an'open ladle to a dull red color (650° c.) during the process of babbitting. Such practice is, of course, detrimental to good results. The effect of various constituents of babbitt are set forth in Iaterials Handbookmas follows: Antimony imparts hardness and moth surface to soft metal alloys, it expands on cooling and unites with cop- per to fem a crystalline alloy having valuable bearing qualities. Lead softens the mixture and raises the anti-friction qualities and increases fluidity. Copper hardens, toughens and raises the melting points. usenic, iron, zinc, and aluminum are generally considered objectionable. Bronze bearing alloys do not appear so involved and complex. The physical properties of any of the bronze listed in Table III are sufficient for electric motor use. The author's personal experience in machining many hundreds of bearings of bronze has lead to the conclusion that a free turning rather tough bronze is sufficient. If the bronze is too hard, the sand cast scale is very detrimental to the cutting tool. The composition of a slitable bronze for electric motor bear- ings would correspond to alloy, grade No. 2, of Table III composed of 80% copper, 10$ tin, and 10$ lead. The Amrican lachinistmstates that this alloy is suitable for high shaft speeds and where Journals are not heat treated. The same source gives compositions of bronze alloys having tensile strengths as high as 33,000 lbs. per sq.in. and compressive strengths up to 28,000 lbs., but no mention is made of the mchinability of such a bronze unless the Brinell numbers of 130-143 could be used as an index. Alloy z of Table III has a Brinell number of 55 and no doubt is readily nmchinable. The melting of bronze metals in the machine shop is not to be reconnended because some understanding of metallurgy is essential. Amaricsn lhchinist states that laboratory control is neces- sary to insure uniformity of structure. 1 bronze bearing, like babbitt, is essentially a mixture of hard and soft crystals, the hard crystals being the supporting media for the load and the softer crystals being the matrix in which the hard crystals are embedded. There is one problem concerning bronze bearing alleys or per- haps certain compositions, which the author has been unable to solve, that is, what causes the bronze to shrink onto the shaft and seize 15 upon overheating. In several cases the entire bearing surface of bronze liners had to be scraped after seizure before the liners could be put back onto the Journal. It was necessary to remove bronze from areas that had not seized and had previously run with sufficient clearance. One experienced motor maintenance man of the author's acquaintance said he had found certain makes of bronze would give this trouble and others would not. he author intended to conduct certain experiments to de- temine the cause, but time does not permit. A considerable amount of research has revealed no mention of such a characteristic. XI. BEARING WEISS AND REMEDIES Bcaring failures are not always caused by overload, lack of oil, or grit in the lubricant. There is one cause that is peculiar to the electrical industry and is known as. electrical bearing currents. Ir. 0. T. Pearce” gives a most comprehensive and complete discussion on the subject and one interested will find his publication very enlight- ening. Under certain conditions, bearing currents are induced in the shaft of electric motors and generators by alternating flux linkages surrounding the shaft. The flow of current through the bearing causes pitting that is extremely detrimntal. Insulating the bearings will, of course, step the flow of current and one will oftentimes find such insulation used in large and important electrical machinery. The pit- ting of the rubbing surfaces is characteristic. An examination of the pits reveals that they are minute craters having raised edges. a micro- scopic inspection of a pit well revealed that the metal was actually fused. It is not easy to find a pit in its original form due to wear that takes place imediately after its formtion. Fig. 8 and 9 show a Journal and bearing damged by electrical bearing currents and will aid in the identification of such troubles. It will be seen that there is very little circumferential alignment as in the case of damage done by abrasives (Fig. 6 and 10). It would therefore appear that the pits were formed almost instantaneously. he raised edges of the pits act as effective cutting edges and destroy the bearing at a very rapid rate. In remachining the Journal, the author has found that the areas surrounding the pits are extremely hard and will dull a high speed cut- ting tool so rapidly that very little progr. can be made. The areas are so hard that an ordinary file has very little effect in removing the metal. It is necessary to take a lathe cut of sufficient depth to get entirely beneath the pits. The hardening no doubt takes place by the metal cooling rapidly from fusion temperature to that of the bearing due to heat absorption of the shaft. matting mterials have a sufficiently high carbon content (approximtely .40) to talne on hardness under such conditims. Insulation of bearings is not always sufficient. Large water-cooled bearings having insulating materials in the pipe connections have been known to develop pitting. In mich instanees contamination of cooling water has been found sufficient to be a good electrical con- . ductor. me question sometimes arises whether static discharge no. such sources as a belt drive may not cause pitting. It is believed not because of an insufficient amount of heat to cause fusion of the metals. If static from belt drives were to cause pitting, there undoubtedly 16 would be mch evidence to support it because of the large number of belt drives in everyday use. flectrical pitting is not always caused by induced currents. In motors having wound rotors of the repulsion-induction type, pitting is very com. This is caused by defective short-circuiting mechanisms. Current generated in the windings, in these mtors, flows through the ahort-circuiting device.through the shaft, through the bearing, thence to the frame and returns to the windings through the commtator brushes. Though the motor has a brush-lifting device, it is necessary for the short ciruiter and the brushes to be in contact with the commtator for a short period of time while the motor is accelerating during starting. It is during this internal that the damage is done. Ihen ball bearings are used, the danmge is much more severe and pronounced. Large slip ring motors are also mibJect to this trouble. m. II'ITING OI BEARINGS There are several errors entering into the machining of bear- ings, particularly in the boring reaming or otherwise cutting the metal from the inside surfaces. no Journal lends itself well to turning or grinding because its surface is external. The hole in the and bell of the motor and the hole in the bearing receiving the Journal are quite apt to have various irregularities due to the inherent tendency of reamers to produce chatter marks and to cut a greater amount from one side than the other if the bore surfaces are unsynetrical and if the end of the hole receiving the reamer is not square. Tor instance, if a hearing such as shown in 11g. 80, right, having a large cut-away sec- tion for oil wick packing were being roamed, the reamer would be crowded off center toward the hole. Unsymetrical oil groving produces the same result. Considerable error due to both conditions acting together may be present in a reamed bearing and becomes greater with increased re- moval of metal. Holes in the end bells of motors are usually somewhat out of round, oftentimes tapered, and in many cases out of parallel with the center of rotation of the shaft. Self-aligning hearings in the larger motors are naturally free from the errors of misalignment, but not necessarily free from other errors Just mentioned. In practice the errors of reaming are reduced to a practical mini-am by reaming only such small amounts as to produce a smooth finish, usually Just suf- ficient to remove boring tool irregularities. To produce a perfectly round hole by reaming requires con- siderable attention to the finer points of reamer construction and the art of cutting metals. The usual run of expansion reamers are noto- riously poor tools for precision work. They can, however, be made to produce reasonably satisfactory work after hand stoning and by careful manipulation. It is a well-known fact that the cutting edge of a reamer met have a certain small land Just behind the cutting edge to prevent the blade from "hogging in'. The width of this land governs largely 1" the stability or firmess of the reamer in cutting. If too wide, the reamer binds. If too narrow, it produces a haggled surface. when the width is right the operation is firm, cutting is free, and the hole has a burnished appearance. Different metals, of course, require different widths of lands. The operation of boring in a lathe produces a hole whose aver- age trueness leaves little to be desired; however, the surface finish is ordinarily too rough for bearing purposes. Beaming or scraping is re- sorted to for producing smoothness. For precise work the reamer is too treacherous. Hand scraping using prussian blue or other suitable indi- cator is to be preferred. It should be Inspt in mind that irregularities of surface contour .y reduce the load-carrying ability and normal length of life considerably. fig. 39 shows the cross section of a one-bladed reamer perfected by the author for reaming holes with the maxim degree of roundness and of predetermined diameter. The enlarged section of the blade shows the cutter having a land as described. The amount of clear- ance behind the land is determined by methods used in mufacture and has nothing to do with the cutting action. This reamer was designed to have maximm support opposite the cutting edge so as to avoid chattering. The reamer is of the adjustable type and is especially adaptable for line reaming because of its inherent stiffness. Iith conventional type mlti-bladed reamers the 'nuting reduces the cross section so that the reamer loses the necessary rigidity for line reaming when the bearings are far apart as in motor construction. The author has used the one-bladed reamer with marked success in the making of precision target rifle barrels and considers this type to be one of the most effective where precise reaming is desired. There are a few fundamentals, however, that imist not be over- looked in its eenstruction and operation. Referring to 11g. 40, it will be noted that the pilot is not a tight fit in the hole being reamed either before or after the body makes contact. Fig. 411 shows the pilot supperting the cutter Just prior to the body entering the hole. Fig. 413 shows the body supporting the cutter and being guided by the finished hole while the pilot is relieved of the duty of supporting after the reamer body has entered. The support of the cutter is directly opposite the cutting edge and the pilot enly serves as a guide in the axial di- rection. The cutting edge mst overhand the reamer body slightly and its height H met be less than the clearance between the pilot and the unfinished hole. If there is any variation in heighth of the cutter, it must not be greater toward the middle of the body, otherwise the sup- port of the body on the opposite side will be lost. It is desirable to have the front end of the blade a half-thousandths of an inch or so higher than the rear end. Copieue lubrication should be applied so as to keep chips from working under the reamer bow and producing an oversize hole or the chip clearance groove can be partially filled with a rather sticky 18 grease so as to hold the chips into the groove. This type of reamer is intended for removal of very small amounts of metal at a time and will produce excellent results in the hands of careful and competent workmen. Line reaming is particularly desirable for fractional horse power motors because of the inaccuracies found in present manufacture probably due to circumstances resulting from.competition. The more re- moval of the old bushing and pressing in of a new one, even though the new one is perfectly concentric, usually results in a poorly aligned Job due to the inaccuracies of the machining of the end bells. Iith small motors the line reaming method is the most practical. Large bear- ings are best scraped in because large reamers are unwieldly and their cost prohibitive unless large quantity production is being carried on. The conventional type of bearing scraper does nicely in scraping babbitt but when used on bronze it lacks rigidity, does not have preper clearance, and cuts over too large a surface. The author has been called upon a number of times to scrape in bronze bearings that had seized to the shaft while running. The conventional type of scraper was found to be of little value. By experimenting, a design was worked out that gave very good performance. Fig. 48 shows a set ranging in size from.6 to 14 inches, which was found suitable for both small and large motor bearings. These were made from.standard half round files without drawing their original temper. They are used in much the same manner as the conventional scraper. They differ in shape principally in that there is no offset in the handle, are much wider across cutting edges, and are more rounded at their points. Being straight in body they are very rigid because the cutting edge is in direct line with the points of support or operators' hands. The narrowness of the blade of the conventional type gives very little clearance to the cutting edge. 0n the other hand, with this type one can get almost any desired clear- ance by using various portions of the blade. Near the point the blade is narrow and the cutting clearance small, while toward the middle it becomes greater. If the cutting action is not quite correct for a given diameter hole and a given scraper;the next size larger or smaller scraper will undoubtedly be found satisfactory. Ihen the bronze sleeve is firmly supported as in a vice, one can literally cut shavings with remarkably little effort. The cutting edge is ground so as to have very little, if any, rake while cutting, The much positive rake causes chatter and gives the user a sense of poor control. XIII. ‘IIILD PROBLEMS Three causes of’motor bearing troubles have already been men- tioned; namely, the seizing of bronze liners, shaft scoring due to foundry scale, and failure due to electrical bearing currents. There are also a number of other troubles. Loss of oil from.a bearing is by no means a minor one. The cause oftentimes presents a baffling problem. The author has had first-hand experience with five causes as follows: rotor fun suction, foaming, ring throwing, vibrating shaft, and surface 19 creepage. One is quite apt to suspect the fan of the rotor especially when rotor speeds are increased; however, it has been found that they seldom.are the cause provided the bearing housing design is not at fault. Only one case has been found wherein the fan suction was proved to be the cause. Referring to Fig. 43, it will be noted that in the upper part of the housing there is a hole through the central wall designated as "pressure equalizing hole". When this hole is not present, or some other form.of air passage between the two compartments, a slight vacuum. on one side of the wall causes the oil level to rise on that side and to overflow through the opening around the shaft and into the motor. The difference in pressure between the two sides need not be very great to give a difference of say 1' between the levels. Cases of this kind are easily taken care of by providing a pressure-equalizing hole. The only oil that can then be drawn from_the hearing will be in the form of a mist carried out with air currents. Air currents are re- duced to a minimum or completely stopped with external air by passes, as in the new Westinghouse design, or by sealing the opening around the shaft with felt or other substances. Occasionally what would appear to be fan suction is nothing more than the use of too heavy a lubricating oil. High ring speeds are quite apt to carry air into the oil at a higher rate than the air will separate from the oil resulting in the formation of a foamrwhich overb flows the housing and becomes thrown into the motor windings by the rotor. An oil of lighter body is all that is required as a preventive. Quite often the speed of the ring is sufficient to cause a 'veritable shower of’oil within the housing and in such cases the oil is literally thrown out as a splatter. Globules of oil will be observed to come out of the housing between the shaft and the opening for the shaft. The use of'a heavier bodied oil will oftentimes stop this trouble. In some cases barriers are necessary and in other cases a felt seal is required, depending upon the construction of the housing. All motors ranging above the fractional horse power sizes have oil slingers designed to return oil to the housing and also to eliminate surface creepage toward the rotor. In cases where the oil ring is on the side of the wall next to the motor, drops of oil may fall from the upper overhanging portion ef'the housing and hit upon therotating shaft. If it strikes on one of the slingers, it will, of course, be returned to the housing. If upon a straight portion,it will be partially thrown into the motor. It is, therefore, proper in such cases to have the slingers part in and part out of the housing as shown in 11g. 43. .A badly balanced rotor having a worn bearing has been known to throw oil out along the shaft in spurts as the shaft whipped from one side of the bearing to the other. Balancing the rotor, installing a new bearing, or providing a felt seal will stop the leakage. It is desirable to have the rotor in balance and to have a new bearing, but oftentimes 'a seal met be installed, at least temporarily. 80 Surface creepage is more or less prevalent in all motors. Quantities lost are usually insignificant except in cases where the oil level is carried too high in the oil inspection cup. .The level is best carried at least 3/8' below the top. 011 cups are sometimes omitted and in their place a rough hole is cored in the casting or a small hole is drilled through the housing. Surface creepage is usually bad when such holes are provided. If the creepage is objectionable, standard oil cups can ordinarily be fitted to the housing Another serious cause of bearing failure is that due to defec- tive oil rings. Oftentimes a failure can be traced to a burr on the ring that happened to catch somewhere in the.ring slot and stop rotating. The stopping is sometimes assisted by a cold viscous oil. The ring shown in fig. 12 was taken from a 300 h.p. motor running 1800 r.p.m. Bearing trouble had not been experienced possibly because the bearing had two rings or perhaps the ring had never actually failed to rotate. 0n the right of center will be seen a bright strip where slippage had taken place. .At the bottom.will be seen a series of‘overlapping ripples similar to rats formed in a gravel road by auto traffic. Apparently there had been severe slipping followed by combined slipping and dancing. The ripples actually overlapped each other by the surface metal flowing frmm one cavity into the other. It will also be noted that the inside edges of the ring had been left very rough from.cutting off with a lathe tool. This ring had been made fromba piece of brass tubing and was found to be considerably out of round. Rings should be round, of even cross section, free from.burrs, and made of’a material that resists wear. Bronze is the best material in semen use at the present time. Trom.what has been written it is quite obvious that electric ‘motor bearings like other commercial products may be well or poorly made from.the standpoint of‘design, materials, and workmanship. One oftenp times gets the hmpression.upon the inspection of bearings, and this ap- plies usually to the whole mtor, that there is always some one who can build a bearing a little worse and a little cheaper and still find a sale for his product. In closing, the author wishes to express his earnest opinion that there is a need for standardized practice among manufacturers and a general enlightening of engineers and trades men toward bearing de- signs and excellence of'workmanship. It is hoped that this thesis may in some manner he used to bring about this accomplishment. 1. 2. 3. 4. 5. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 21 BIBLIOGRAPHY Encyclopedia Britannica, Vol. 14, 14th Edition. 'niree Thousand Years of Progress in the Development of Machinery and Lubricants for the Hand Crafts, by Iilliam F. Parish. Mill 8c Factory, March, 1935. PhilosOphical Transactions, 1886. Some Practical Deductions from the Theory of Lubrication of Short Cylindrical Bearings, by Cardullo, A.S.M.E. Transactions, 1930. M.S.P.-52-12. On the Theory of Lubrication, Phil. Trans. Roy. Soc., London, Vol. 177. On Problems in the Theory of FluidA-Film Lubrication lith an Experi- mental Model of Solution, by Kingsbury. A.S.M.E. Transactions, 1931, A.P.M.o33-6. Optimum Conditions in Journal Bearings, by Kingsbury. A.3.M.E. Transactions, 1932, R.P.-54-'7. Effects of Side Leakage in 120 Degree Centrally Supported Journal Bearings, by Needs. A Graphical Study of Journal Lubrication, by Howarth. Part I, A.S.M.E. Transactions, 1923, Vol. 45, p. 421; Part II, 1.3.14.3. Transactions No. 1936, p. 809, 1924. ' Charts for Studying the 011 Film in Bearings, by Karelitz. A.S.M.E. Transactions No. 1989, 1925. On the Laws of Lubrication of Journal Bearings, by Hersey. A.S.M.E. Transactions, 1915, No. 1483, p. 167. Pressure Distribution in Oil Films of Journal Bearings, by McKee- lchee. A.S.M.E. Transactions, RP-Sd-S, 1932. Current Practice in Pressures, Speeds, Clearances, and Lubrication of Oil Film Bearings, by Howarth. A.S.M.E. Transactions, M.S.P.- 56-2, 1934. Frictional Characteristics of Journal Bearings in the Region of IThin Film Lubrication, by McKee-McKee. S.A.E. Journal, Sept., 1932. An Investigation of the Perfonnance of Iaste Packed Bearings, by Karelitz. A.S.M.E. Transactions, A.P.M.-50-l, 19$. Perfornmnce of Oil Ring Bearings. A.S.M.E. Transactions, A.P.M.- 52-5, 1930s 17. 18. 19. 20. 21. 22. 23. 24. 26. 27. Lubrication and Lubricants, by Battle. Common Errors in Designing and machining Bearings, by Christopher H. Bierbaum, A.S.M;E. Transactions No. 1720, 1919. Elements of Machine Design, Kimball and Barr, Second Edition. Bearings and Their Lubrication, by Alford. machine Design, Leutweiler, First Edition. Amer. Soc. Testing.Materia1s, 1923. Recent Development in main and Connecting Rod Bearings, S.A.E. Journal, July , 1934. Babbitting Motor Bearings, by J. S. Dean. Booklet published by lestinghouse Electric and manufacturing Company. Bearings and Bearing thals, by the Industrial Press. American Machinist Reference Sheets, 1930. Bearing Currents, Their Origin and Prevention, by C. T. Pearce. Electrical Journal, August, 1927. materials Handbook, by Brady. MbGraw-Hill Publication. APPENDIX ( FIGURES AND TABLES) 25’ .,4~ a n . ”can Illlfl 8.5015 saganggsggagzsoauouuap -§§§3§3§§3§§§§§3§§§33§§§ E7 . §§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§§ use. one I- eon. l z——J ournal——~ P—Horiaontal—R r-r Vertical -_‘ Allowable Allowable Alla-“able variation variation variation Nomi- low above ‘ above nal Max max Min min Min mm diam diam diameter bore bore bore bore V. 0.375 0.0005 0.377 0.001 0.377 0.001 I/. .500 0.0005 .502 0.001 0.502 0.001 1 |/. .525 0.0005 0.627 0.001 0 627 0.001 '/4 .750 0.0005 0.752 0.001 0.752 0.001 '/. 0.875 0.0005 0.877 0.001 0.877 0.001 I 1 1. 0.0005 1. 2 0.001 1.002 0.001 1V. 1.125 0.0005 1.128 0.001 1.128 0.001 1']. 1.250 0.0005 1.253 0.001 1.253 0.W1 ' ll/g 1.500 0.0005 1.503 0.001 1.503 0.001 1V4 1.750 0.0005 1.753 0.001 1.753 0.001 1 2 2.000 0.0005 2.003 0.001 2.003 01111 21/4 2.250 0.0005 2.253 0.001 2.253 .001 ' 21/; 2.500 0.0005 2.503 0.001 2.503 .001 ‘ 21/4 2.750 0.0005 2.754 0.002 2.754 0.001 1 8.000 0.0005 3.004 0.002 3.004 .001 ‘ 3V4 3.250 0.0005 3.254 0.002 8.254 0.001 ‘ 3V1 3.500 0.001 3.504 0.1112 3.504 0.001 1 4 4.000 0.001 4.005 0.W2 4.005 0.W1 1 4V: 4.500 0.001 4.505 0.002 4.505 0.001 5 5.000 0.W1 5.” 0.002 5.005 0.1112 5']: 5.500 0.001 5.507 0.W2 5.505 0.” 1 5 5.000 0.001 5.“)8 0.” 0.000 0.“ 7 7.1!!) 0.001 7.011 0.1112 7.“ 0.“)2 8 8.01!) 0.001 8.012 0.” 8.“ 0.003 9 8.W0 0.001 0.018 0.004 8.” 0.“)2 10 10.”) 0.W15 10.014 0.“ 10.” 0.” 11 11.4!” 0.W15 11.015 0.“ 11.4!” 0.” ‘ 12 13.000 0.N15 12.010 0.005 12.” 0.” l 18 18.” 0.W15 13.015 0.005 18.“?! 0.” 14 14.“ 0.41115 14.015 0.1»5 14.”? 0.” I 15 15.4!” 0.0015 15.015 0.” 15.” 0.” ‘ 16 In.” o-ml‘ ”.01. 00m 1‘.” 00m . 17 17.” 0.0015 17.018 0.1115 17.” 0.” l 18 18.“ 0.W15 18.018 0.” 18.” 0.” 18 18.” 0.0015 18.018 0.” 18.”! 0.” 30 30.000 0.00 ”.018 0.“ 20M” 0.” l 21 21.“ 0.” 21.018 0.“ 21.” 0.” l‘ 22 . ’ 33.030 0.” 82.” 0.“ 28 88.% 0.“ 28.07 0.” I 34 . 0.” 24.”? 0.“ 1 u ‘ em as” I... 004 ’ “ em 04“ see. ee- 3 ”0m On“ see. as ‘7 ”em 0"” .III on. ‘ ' ”em 0.“ aa-a III a '0.” oi nee! en. 1 ’10“ o. I... one . ”um 00 .000 aa- 88.“ 0.010 .... .. “Om 0.010 8". O. u ”Om 0.0” I... 0.. a 88.024 0.010 .. H. I Table I COMPOSITION AND PHYSICAL Pxoranrras‘ or Wane METAL BEARING ALLOYS Y'eld lam} Ultimate Tim”? PM“ . .. .. . . m, Speafied menace 0‘ Cayuga?! Alloys Ptiint. _ E'ssgio Strength. 3731:1211 1:11:32“ Colinplcte 1%,:3, . lb. per sq. in! Limit. _ lb. per sq. 111.‘ L 1q1iefao- ture Alloy Specific lb. per sq. in! ‘ uon Rumba Gravity Anti- Anti- Covpel'. Tin. Lead. Co .. Tin. Lead. per per ”:3" pet 5.." pet ”$3." per 20°C. 100°C. 20°C. 100°C. 20° 0. 100°C. 20°C. 100°C. 3?, 0%,; 3%,. 8.7:, m: (Eff; 00115 00118 00115 cent N115 cent @111 08115 I 1 ............... 4.5 01.0 4.5 7.34 4.55 00.0 4.52 none 4400 2550 2450 1050 12350 5050 17.0 30 433 223 3% 441 2 ............... 3.5 30.0 7.5 7.30 3.1 50.2 7.4 0.03 5100 3000 3350 1100 14000 3700 24.5 12.0 455 241 550 354 705 424 3 ............... 3} 331 3} 7.45 3.3 33.4 3.3 0.03 5500 3150 5350 1300 17500 0000.270 145 454 240 702 422 015 401 4 ............... 3.0 75.0 13.0 10.0 7.53 3.0 75.0 11.5 102 5550 2150 3200 1550 13150 5000 34.5 12.0 353 134 533 305 710 377 | 5 ............... 3.0 55.0 15.0 13.0 7.75 3.0 55.5 14.1 13.3 5050 2150 3750 1500 15030 5750 32.5 100 353 131 555 205 500 355 0 ............... 1.5 20.0 15.0 53.5 0.33 1.5 10.3 14.5 53.7 3300 3050 3550 1300 14550 3050 21.0 10.5 353 131 531 277 555 340 ............... 10.0 15.0 75.0 0.75 0.11 10.0 14.5 75.0 3550 1500‘ 2500 1350 15550 3150 22.5 10.5 454 240 514 253 540 333 ............... . 5.0 15.0 30.0 10.04 0.14 5.3 14.0 70.4 3400 1750 2550 1200 15500 5150 20.0 0.5 450 237 522 272 545 341 ............... 5.0 10.0 35.0 10.24 0.05 5.0 0.0 34.5 3400 1550 3400 050 14700 5350 10.0 3.5 450 337 403 255 520 327 . ............. 3.0 15.0 33.0 10.07 0.13 3.05157 33.0 3350 1350 3250 1200 15450 5750 17.5 0.0 453 343 507 254 530 333 ........ . .. 15.0 35.0 10.23 0.10 0.00143 31.7 3050 1400 3750 1100 12300 5100 15.0 7.0 471 244 504 252 530 333 13.. ...... .. 10.0 00.0 10.57 0.13 0.11 0.0 30.4 2300 1250 3250 050 13000 5100 14.5 5.5 473 345 403 250 525 320 5 1Tbeeompve-ia1uatlpecimeaswapcylinduinin.inlenstband Media-nation nnitmaxthepoimwbentbedope uthmwMuadmdoed mam-Inn. Hn.diameta.lnachined fmebifleaefinp2in.inlcngtband§in.indiamsteé. The Brinell teatswere Inadeon ebouunfaceolpuallelmaebinedapeameescautmahndhneterbyfiadeepneelmoldatroomtempentun “11417410kame do Table IIa 0.131111110410110! mom 11.500413. dthe 7“ \‘I w themtwtbeoumial 13113013001011.35th m mppliedlotmaeconds l l :1 l i | Li- M. _.___.4_, . J— . SPECIFICATIONS 2011 BABBIT’I‘ METAL 1 Alloy Tin. Antimony. Lead. Copper. 111:: Amy“ Zinc. ; Aluminum, Grade per per per per " " per per No. cent. cent. cont. cent. 02:1. 02:1: cent E cent. 1 ........ 81 4% 0.350 4% 0.08 0.10 none none 2 ........ 89 7% 0.850 35- 0.08 0.10 none none 3 ........ 331 3% 035a 8211 0.03 0.10 none none 4 ........ 75 12 10 3 0 . 08 0.15 none none 5 ....... 65 15 18 2 0.08 0.15 none none 5 ........ 20 15 53 § 1.} 0.03 0.15 none none 7 ....... 10 15 75 0.500 0.20 none none 1 8 ........ 5 15 80 0.501 0.20 none none 8 ........ 5 10 85 0.500 0.20 none none 10 ........ 2 15 83 0.50!I 0.20 none none 11 ........ 15 85 0.501I . 0.25 none none 12 ........ 10 90 0. 500 0.25 none none L__ g yaximum. __ __ _ . .- Tablo IIb ( Tam SHOWING P11231041. Pnornnms or B20142: 131311111106 Menu. ALLOYS. Dunn Coupon-12010. Ultimate Brinell Companion 33; . 8:21.111. in 21.1 ' 75001.: W15. wan. 001mm Ne. Cows. 1111. Lead. 15. pa- cent.1 In . w fi' 1:91: lb. pa- pacnt. pro-1t. percent. 011.:1 80000.). ‘ 011.111.! 1..... ...... 85 10 5 28 000 12.5 50 0.25 0.81 18 M 2 ........... I1 10 10 25 000 8 55 0.25 0.31 15 000 8 ........... 30 10 10 22 M 8 50 0.25 0.32 12 500 4 ........... 77 1 .8 15 M 000 10 48 0.25 0.38 12 000 50 .......... 78 I) 18 000 7 45 0.25 0.33 11000 60 .......... 70 5 35 15 000 5 40 0. 25 0. 33 .. 10 000 mwzvhgdagydgcifldmgomdiegtagmwmwmmaccountol'themtwn 01M Oanbe 1'1‘1101.1-.03100testoweremadoon “"tutaandcut-to-dsc ’The compression teetlmznadeon one. machinodtut cnn(nnd0acfinn)olloq.in.0cctlonalarea.lia. Lilli- TheoomprwondeimhonhmtutakdlastheloadprodmcacompmonmthumcunenofOOOl1n. Table 1!! ' .uéah 33 n .53. "8.1:..8331351987 .1225 v8... ...: 3.3... 3.55.83; 1:633:31? "...—35:43:13....55. Avg“ 44:33H LO '4:— J—o In IILIEIIL 5.... IaFalugau GIECIA‘ a). 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