US2434072A - Tappet construction - Google Patents

Description

Jan. 6, 1948.

J. H. HOERN EI'AL TAPPET CONSTRUCTION Filed June 21, 1944 mi mam m 2 Patented Jan. 6, 1948 TAPPET CONSTRUCTION Joseph H. Hoern and Martin D. Archangeli, Birmingham, Mich., assignors to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application June 21, 1944, Serial No. 541,410

1 4 Claims.

This invention relates to internal combustion engines and particularly to valve tappets employed in connection therewith, the principal object being the provision of a Valve tappet of minimum weight and in which the distortion thereof under load is so controlled as to minimize if not eliminate the possibility of seizure of the tappet in its guide.

Objects of the invention include the provision of a thin walled generally cylindrical hollow valve tappet so constructed and arranged that when under axial compressive load at least certain areas thereof will tend to contract in diameter, thereby minimizing the tendency of other portions thereof to bulge or expand under such conditions; the provision of a valve tappet of hollow cylindrical construction and of such Wall thickness that it would increase in diameter between its ends under load if not prevented, so formed and constructed that the tendency to radially expand under load is reversed over at least certain portions thereof; the provision of a Valve tappet as above described which actually decreases in radial dimensions over certain portions thereof under axial load; the provision of a valve tappet of hollow cylindrical construction the walls of which are generally of such thinness that although capable of supporting compressive ads normally met with in service are incapable of so doing without radial expansion unless otherwise prevented, together with means cooperating with such walls tending to reverse the tendency of radial expansion over certain areas thereof under such compressive forces as are met with in service; the provision of a valve tappet as above described in which such means for reversing the tendency towards radial enlargement consists of a bead or rib integral with the walls of the tappet intermediate the ends thereof and extending circumferentially about the interior of the tappet, the provision of a valve tappet as above described in which the internal rib is of such size as to effect an actual radial contraction of the walls of the tappet over and adjacent to the axial length of such rib under the conditions stated; and the provision of avalve tappet as above described in which the rib is positioned at that point in the length of the tappet which would radially enlarge to the greatest extent under a compressive load in the absence of such rib.

Further objects of the invention include the provision of an internal combustion engine having a valve, a cam and an operative connection between the valve and. cam including a relatively enlongated valve tappet having a generally. cy-

lindrical body guided in a complementary bore of the engine, and spring means constantly urging the valve toward closed position, the tappet being hollow and having walls of such thickness that when otherwise unrestrained would bulge under the load imposed thereon in the opening of the valve against the force of said spring means and in overcoming the inertia of the valve, resulting in binding of the tappet in its bore, together with an internal circumferential rib in the tappet formed integrally with the inner walls thereof and of such size and so positioned as to reverse the tendency of the tappet to expand in the immediate area of the rib and to such extent as to substantially if not completely offset the binding effects of the tappet in the bor under load which would otherwise occur.

The above being among the objects of the present invention, the same consists in certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views,

Fig, 1 is a partially broken, partially sectioned view taken through an internal combustion engine provided with a valve tappet constructed in accordance with the present invention;

Fig. 2 is an enlarged sectional view taken axially through the body of the tappet shown in the engine of Fig. 1, illustrating in exaggerated form and by dotted lines the relative expansion and contraction of different portions thereof in service;

Fig. 3 is a view of a tappet substantially identical to that shown in Fig. 2 with the exception of the internal rib of the present invention which is not present, and illustrating by dotted lines and in exaggerated form or extent the manner in which it would radially expand under compressive load in service;

Fig. 4 is a view similar to Fig. 2 but illustrating the tappet in an initial stage of construction and illustrating the manner in which the internal rib is formed therein; and,

Fig. 5 is a view similar to Fig, 2 but illustrating a tappet of relatively greater length as compared to its diameter and the use of a plurality of internal ribs to offset the radial expansion thereof under compressive forces met with in service.

It'is a generally accepted fact that the most desirable engine for aircraft use is that one delivering the greatest horsepower per pound of weight of the engine, providing the engine is capable of operating for a reasonable length of time without undue danger of failure of its operating parts. The energies of substantially all airplane engine designers are directed to this end at the present time; There are two methods by means of which such ideals may be approached, one of which is by increasing the efficiency and, therefore, the power of an engine of particular size, without increasing the weight thereof, and the other one of which is the reduction of the weight of the operating partso'f the engine itself without reducing its power." The present invention has to do with the latter'types of endeavor. In other words, its object is to reduce the weight of an operating part of the engine, without endangering failure of the engine becauseof some structural or other defect resulting therefrom and, therefore, to provide such part which Will be of lighter w'eig'ht' than thoseh'eretofo're employed for the same purpose, that will operate equally if not more'efiic'iently and without danger of causing failure o'f'theengine either because of breakage or orda'mage tosuch partv itself, or parts with which itis operatively associated, The particular parts of the engine to which the present invention specifically relates are the valve t appets therefor.

In present dayairplane' engines valve tappets are necessarily madetr a material length and of a material diameter"in order to provide sufficient bearing area between themselves and their guides to withstand the movement and forces to which they are subjected in operation. For this reason they are usually made hollow in order to reduce the Weight thereof. The greatest saving in Weight in such tappets is obviously capable of being obtained byr'educing the wall thickness thereof, but before the present invention the reduction in such wall thicknessha's been definitely limitedby reason of the fact that where the wall thickness has been reduced 'beyonda certain extent, mine it is of sufficient thickness, 'With' a' reasonable factor of" safety, to take the "axial compressive load applied to it inservice during the opening of a valve without crushing axially, nevertheless the body of the'tappet expands under such compressive forces to'such "anext'ent as to cause the tappet body to bind in its guide, or at least expand to such an extent as to restrict the amount of lubricantbetween' itand the guide sufficiently to cause'scoring of the walls of'the tappet or guide and consequent seizure. of the tappet in the guide. The problem, therefore, at the time of the conception o'fthe present invention had not been solved to a satisfactory extent inasmuch as the walls of such tappets were still considered to be of a thick'ne'ss greater than that required to carry the loads to which they were'subj ected In accordance with the present invention it has been discovered that su'ch'tappets may be made of a wall thickness or, better stated, thinness, that Were'it not for the feature of the present invention the tappets would be commercially impractical because 'they'wouldradi'ally expand under load to such "an extent as to present a serious problem'of seizure in their guides during operation,

In accordance with the present invention such radial expansion is minimized to such an extent as to render 'it'nodong'er a problem by forming one or more circumferential ribs integral with the-thin walls ofthe ta'pp'e't body interiorly thereof. "It has beenfou'nd' that by-th'e use of such lib oriibs judiciously 'lobated on the interior of and in contracting minimize the radial expansive movements of those wall portions of the tappet immediately proximate thereto.

The ribs'thus provided in accordance with the present invention are not required to be of great '-'a'xial or radial dimensions as compared to the overall axial andfradial dimensions of the tappet.

In fact su'ch'ribs are not required to be of substantiallygreater radial dimensions than the wall thickness required in a tappet body which, when not provided with such ribs, Will not radially expand under load beyond safely permissible limits. 'The result is. th'atby thepractices of the present invention the weight of such tappets may be materially reduced vwithoutotherwise affecting the desired operating characteristics. of Y the tappet.

' It will be appreciated, of course, thatalthough the remarksgiven above are particularly directed to the importance of the present invention. in connection with the tappets for aircraft engines, the reduction in weightof operating parts including tap'pets in all types of engines is usually recognizedas' desirable,v and'equivalent reduction in weight may be realized by the application'of the present invention to other types of engines even though in such cases the reduction in weight may not be of as great importance. It will also be appreciated that" the tappet of the present invention is adaptable for use in various types of engines having "various forms of valve mechanisms, that shown in Fig. 1 being simply illustrative of the application of the invention to one type of engine having one type of valve operating mechanism and simply for thepurpose of illustration and not limitation.

The engine shown in. Fig. 1. will be seen to include a crankcase ill having a cylinder block I2 in which is. received alcylinder. liner M in which a piston E'Gis .reciprocably received in a conventional manner... A conventional crankshaft. I8 is rotatably supported inthe. crankcaselfi bysuitable bearingssuch as: 20. and is conventionally connectedby a connecting rod22 with thepiston it in the. cylinder liner I l} .The' cylinder block 12 is provided. with a valveport Z icQmmunicating an .intakeor an eXhaustpassage-25 with the space above the piston. l6..in.the. cylinder liner. I4, a valve 28. serving to control theopening and closing of the porter... The valve 28 isguided inits reciproca'ble movements by a valve guide 39 and spring means indicated generally at 32 cooperate withthe valve.28. in .a conventional manner to constantly .urge. it :towards closed position; The valve 28 is openedagainst the force of thespring means 32 'b-y'means of a. rocker arm 34 p'ivotally mounted on the. cylinder block as at =39; The rocker arm 3:1. is operated from the crankshaft i8 by means of av cam 33 concentric with the crankshaftylii and driven-therefrom." and acting through avalve tappet indicated inFig. 1 generally at it and a push rod 42. The valve tappet :25 is guided in its reciprocating movements in the bore of a tappetguide l i. carried by a member suitably and rigidlyfixed to thecrankcase. l0 and/or cylinder .block i i 2.

Although the. present. invention is. adaptable to any of the various forms of tappets having hollow cylindrical bodies, by way of illustration the particular tappet 40 shown comprises a main body portion indicated generally at 50, the lower end of which is bifurcated as at 52 and Within which is received a roller 54 which rides upon the periphery of the cam 38, the roller 54 being rotatably mounted in the bifurcated lower end of the main body portion by means of a pin 56 preferably pressed fitted in a bore 58 extending transversely through the legs of the bifurcated lower end of the main body portion 50. The major portion of the main body portion 50 is hollow and open at its upper .end which is closed by a shouldered plug 60 received therein and the shoulder of which seats upon the upper end of the main body portion 50. The plug 60 is provided with a partially spherical seat 62 therein'in which the lower ball end of the push rod 42 is received. The hollow walls of the main body portion 50 are imperforate except for one or more relatively small holes 64 provided therethrough adjacent the lower end of the hollow interior of the main body portion 50 and which hole or holes are adapted to be intermittently aligned during operation with an oil passage 56 leading to the bore of the tappet guide 44 and connected as by means of a tube 68 with the pressure lubricating system of the engine. The oil thus led to the interior of the tappet is discharged upwardly through a central hole in the plug 60 and into the interior of the push rod, from which it is carried to the bearing for the rocker arm 34. The oil in the passage 66 in being fed to the bore of the guide 44 serves to lubricate the wearing surfaces between the guide and the tappet 40.

The main body portion 50 of the valve tappet 40 is illustrated in greater detail in Fig. 2 and it will be understood that it is the character of the hollow walls thereof that constitutes the gist of the present invention. As indicated in Fig. 2 the bore Ill extends from the upper end of the main body portion 50 to a point immediately above the bifurcation 52 in the lower end thereof where such bifurcation is employed, otherwise into a similar relation with the cam contacting face of such end of the main body portion where the tappet is formed for direct engagement with an operating cam and without the inter-position of a roller such as 54. Preferably and as indicated in Fig. 2 the substantially imperforate walls of the hollow portion of the main body portion 52 are thickened as at 12 adjacent the open end of the tappet so as to better prepare it for reception of the plug 60 or the equivalent for transmitting the load therefrom with less liability of deformation or the like of such end. It will be appreciated that the walls of the hollow portion of the tappet body 50 are unusually thin as compared to the wall thicknesses of similar constructions employed in conventional practice. For instance, in a tappet having such thin wall portion approximately 2 long and an external diameter of 1% of an inch the wall thickness may be on the order of of an inch. This size of tappet conforms in external dimensions to those now conventionally employed in conventional types of large radial engines now being produced in great quantities for aircraft use, but in which tappets a wall thickness of substantially twice or more than that indicated is conventionally being employed.

In accordance with the present invention an internal rib or bead 14 is formed integrally with the thin walls of the body 50 and preferably but 75,

not necessarily midway between the thickened upper end 12 and the closed lower end thereof.

Preferably it is midway the length of the thin.

walled portion where the length of the thin walled portion is such that one such rib will suflice. The rib or bead I4 is circumferentially unbroken and its cross-sectional configuration and axial extent is not important. In other words, its axial extent may be approximately as small as its radial dimension, or on the other hand, it may gradually taper from a high point at its axial midpoint, equally or unequally, in opposite directions to point or points adjacent the ends of the thin walled portion. In the particular case shown its cross-sectional configuration approximately conforms to parts of a segment of a circle and it is approximately fifteen times as long as it is thick, this being by way of illustration illustrating one form and size of rib or head which has proven successful in tappets of the size stated and subjected to the loads met with in engines of the type referred to. The radial thickness of the rib or head 14 in the particular example shown is substantially equal to the wall thickness of the thin walled portion of the main body portion 50.

Referring now to Fig. 3 a tappet body is shown in which the various parts thereof are indicatedby the same numerals as in Fig. 2 except that such numeralsbear a prime mark. The tappet shown in Fig. 3 is identical to that shown in Fig. 2 with the exception that the rib 14 is eliminated, the thin side walls being of uniform thickness from end-to-end. When the tappet shown in Fig. 3 is subjected tothe load conventionally met with in an engine of the size and type described, when the maximum compressive load is applied to it the side walls expand as indicated in greatly exaggerated form by the dotted lines 80, such expansion following Poissons ratio and in amounts up to 0.0007". Inasmuch as these tappets are fitted in their guides in actual practice as close as possible and still permit a running fit, normally requiring a clearance between the tappet and its guide of 0.0005" or less, it will be appreciated that under such conditions the valve tappet body shown in Fig. 3 will expand to'such an extent in service as to take up all clearance between it and the guide, eliminating the lubricant to a great extent and in a relatively short time causing a seizure between the tappet and its guide. On the other hand, by the employment of a rib such as the rib 14 in Fig. 2 this expansion under load can be completely or substantially completely eliminated so that even in spite of the equivalently thin walls and identical loads the valve tappetbody illustrated in Fig. 2 will maintain a desired, or at least a workable, degree of clearance between it and the walls of its guide.

Theoretically the deformation of the valve body shown in Fig. 2 will include an expansion of it as indicated in greatly exaggerated form by the dotted lines 82 between the rib l4 and the opposite end portions of the tappet body 50, and a radial contraction, indicated in greatly exaggerated form by the dotted line 84 connecting the dotted lines 82, over the axial length of the rib 14 and portions of the thin walls immediately adjacent thereto. In actual practice, however, no substantial increase in the diameter of the body of the tappet between the ribs 74 and the opposite ends of the tappet has been observed, but the central portion over the axial length of the rib 14 has shown a decrease in diameter of 0.0003" under the same loads as have caused an expansion of 0.0007" with the construction illustrated in Fig. 3.

condition of deformationundenloadmay betob tained;.- Ordinarily it. will be desirable tosmake the ribs 14' o'flsuch radial .thicknessas to maintain the major-areas of the thin Walled portion oftheitnbe. againstisubstantial' increase in radial-dimensions underloadand so as to, inefiecn maintainsuch;

major areas at'substa'ntially the same; diameter-as that determined "f or .the properaclearance for the tappet in its cooperating guide.whenithentappet body is infree and unstressed conditions: gThiS is for the reason that undersuch-circumstances the fit of thextaplp'et body in the. guide will .be constant under. alll conditions, that i a'whether it launder load ornot: The small axial length ofJtheita'ppet.

body; under-I such conditions which will decrease in-external dimensions will not be Zlargev enoughtoma-terially detract iromthe desiredlarea of con-f tact between the .tappet body land fits guide and will; therefore, :not materiallyztaffect the Wear characteristics of the tappet inl'the guide.

'The-terin :thin walled has heretofore been employed to designate a characteristics of the valve tappet oflthe present invention and the only specific. example given has been :a tappet, having such thin' walls of certainlength=and-diameter and of approximately 3 2* of an inch iii-thickness. Itwill be appreciated, however, that the term thiniwalled is'a relative term and what m'ay-be thin Walled in one construction..mayhnot beso considered in another, dependingzupon' the 1re1a-.

tivellength of the thin Walledsection ascompared to its 1 diameter, the maximum load which the tap-. pet is required toltransm'it through it, the material from whichthe. tappet ismade-andits con-M dition of hardness, etc; The term"fthiniwalli. as herein employed is intended to-mean a wallet such thickness that under themaximum :loads which it is designed. to carry. in service the thin walledportion of the tappet bodywouldradially expand to suchadegree as to takenup substan:

tially all or most of the clearance intended. to ex-.

ist between it and. the wall-of thecooperating guide and thereby endangeristicking ot the :tappet bodyin the guide, were itnotjor the presenceio'f the internal rib or ribs. of the. present invention.

Althoughthe internal .ribor ribs of the resent,

invention may; be provided in the boreof the..tap.-. pet-body in any suitable; or. conventionallmannerfthe methodof forming them illustrated in 'Fig. 4 is; preferredparticularly inviewof thefact that the jnternaLsur-faces of the. main: bodyeportions, of such tappets should befof aismocth= andnpole ished. nature, which effect would be rdifficult to. obtain if it were attempted tomachine the ribs directlyin the bore of the tappet body; .Acoordms. ,tqthe, method disclosed in Fig. and which tact uthat. it iscfully; .cylindricaliland is: notn ob.-'

structed bylanyribisuch as-thezrib 14 or anyxcon: strictionisuch as is provided bythe thickened; up- 13811:;p01ti0h1 L2 in. the yfinal product... QThe :lowerv ends or theablankshown in Figai-may be. substantiallyiidenti ca-l to thessizean-d shape of, .the'llower endoithe finished tappet except that it-neecbnot bezbifuncatedmor provided with thec-rossl-hole 58 QJSZIWHI'LQQCHI' inlthe .nnal product, these features nreferablyxbeingladded later.

In theaaxial length oi-theblank in Fig.4 corresponding :witli'the: position ofxthe 'rib 14. inthe finallnnroductgthe. blank. is:;.extern ally provided with az'circumferentially :extending rib or bead dflrwhic'h is of; across-sectional area substantially equal toithe cross-sectional area of the head l4 inxitheufinal product; Its l cross-sectional contour may bevaried to obtaimany .desiredcross-sectional'sconfiguration of the bead L4. in. thetfinal productzasiwill; be readily appreciated.- At its upperiendthe:blanklshown in. Fig. .4 is provided with increased iwall' thickness providing a radially outwardly proj ecting integral.- collar pore tiontflhthereon), the. same being of. substantially the same .orsubstantially greater cross-sectional arearas-thegthickened, .end' 12 desired in the .final product.

: Thellowen solid end of the blank shownin Fig. 4-

anditaboneodescribed is inserted into a ring die 94-, a'iiplungerzsuch as1' -96- iswinserted intothe bore s-flaand against the solid bottom wall thereof, and a relative. force is exerted between the olungenliifi .andthering die 94: to force the blank throughlthe ring dieil i. lnasmuc-h a's the .bore 98. inthe 'ring diet 94 is substantially= the: same as the diameter 86 of the blank, in pushing the blank through the ring. die the, head: or rib. 9D isl; displacedtradially. inwardly; until it is located inrthe plane. of; the walls ofthe body and an equiilalent, -amount of. metal is. projected radially inwar ly-0f thebore 8,8 to formnthelribl l4. inthe finalproduct, 1 Likewise that portion ot-the thickened r-endtdz oithe; blank which is, located outwar dly of, thiegdiameter 8i; isatorced inwardly .until i slollter'. diameter; is 'the, same-as. the diameter 88 ii ore. in smooth and polished condition before the slash-mentioned operations, it will. be appreciated;,that the; walls; of 1 the bore; Hi, including h :innensnrfaces of. the :rib' Hi and. the thickened end-,-wall portionulz; willbe;correspondingly smop .rand polished in the finalrproduct.

.1After;-rthe slash-mentioned operation it will usually be desirableltowreemachinethe internal snrifaceofithe th'ickenedtend 1.2' to insure its core tzsiz-ezzand concentricity withthe axis of the loadlbeingrapplied to thetappet body-,the greater the re1lative :length as compared to the diameter the greater the amount of radial expansion." In such:v casesitmay-be snecessary' to employ two or more internal ribs such as the ribsfl4-heretof0re described inbrder to properly control the thin walls against undue radial expansion. Such construction is illustrated in Fig. which is identical to the construction illustrated in Fig. 2 except for the relative length as compared to the diam eter, Inasmuch as this is the only change from the prior construction, equivalent parts therein are indicated by the same numerals as in Fig. 2 except that such numerals bear a double prime mark. In this case it will be noted that two ribs 14" are employed, these being so positioned with respect to each other and the length of the thin walled portion of the tappet body as to be substantially equally spaced from each other and from the corresponding heavier end portions of the tappet body. In this case the two ribs have the eifect of breaking up the length of the thin Walled portion of the tappet body 50" into three relatively short sections, whereas in the previously described construction the rib M broke up the corresponding length of the body 59 into two such sections, Any desired number of ribs may, of course, be employed but it is, of course, desirable to use the minimum number capable of accomplishing desired results inasmuch as under such circumstances a tappet body of minimum weight will be provided.

One thing to be noted in connection with the present invention is that the rib or ribs T4 provided in accordance with the present invention are not reinforcing ribs in any sense as they have little if any function in this respect. Their function is to provide a center of mass located radially inwardly of the center of mass of the thin side walls per se which under the force of compression applied to the tappet will cause that and adjacent areas of the thin walls to minimize and preferably reverse its tendency toward radial outward expansion which would otherwise occur, and even prevent or actually reverse such outward expanding of the thin walls and effect an actual radial contraction thereof if desired. As previously stated, the thin walls without such rib or ribs are themselves capable of taking the compression loads to which they are subjected in service without permanent deformation but not without temporary deformation, so they do not require such ribs for reinforcing purposes. The ribs are provided for controlling the temporary distortion which occurs under such circumstances.

Having thus described our invention, what we claim by Letters Patent is:

1. A hollow tappet body of circular cross-sectional configuration having substantially imperforate thin side walls of such thickness that unless otherwise prevented such thin side walls will radially expand, without permanent deformation, under the compressive loads to which it is subjected in service, and a circumferentially unbroken rib integral with said side wall on the interior thereof and intermediate the ends of said side wall, said rib being axially elongated and of a length relatively greater than either its radial thickness or thickness of the wall of the tappet body whereby to reverse the tendency of said side wall, over the axial length of said rib, to radially expand under said compressive loads in service.

2. A valve tappet including a body of circular cross-sectional configuration and including a portion having a substantially circumferentially unbroken wall of such thickness that unlessotherwise prevented it will expand, without permanent deformation, under the compressive loads to which it is subjected in service, and a rib formed integrally with the inner surfaces of said walls and projecting radially inwardly therefrom in circumferentially unbroken condition intermediate the ends of said walls, the radial dimension of said wall and rib combined being substantially no greater than the thickness of the corresponding wall of a tappet of the same size and material but of constant and suificient wall thickness to withstand said loads in service without material deformation, and said rib having an axial length materially greater than the thickness of either the rib or wall whereby to reverse the tendency of said wall at and adjacent said rib to radially expand under said loads.

3. In a tappet, in combination, a hollow main body portion having a substantially unbroken wall portion bounded at each axial end thereof with more rigid wall portions, the first-mentioned wall portion being of such thickness that unless otherwise prevented it will radially expand under the compressive loads to which said tappet is subjected in service to an undesirable extent but without permanent deformation, and a circumferentially unbroken rib extending circumferentially around the bore of said tappet intermediate the ends of said first-mentioned wall portion and formed integrally with said first-mentioned wall portion, said rib being of greater length than the thickness of either the rib or wall whereby to eifect a reduction in the diameter of said wall portion over at least the axial length of said rib under the maximum value of said loads.

4. In a tappet, in combination, a hollow main body portion having a substantially unbroken wall portion bounded at each axial end thereof with more rigid wall portions, the first-mentioned wall portion being relatively long as compared to its diameter and being of such thickness that unless otherwise prevented it will radially expand under the compressive loads to which said tappet is subjected in service to an undesirable extent but without permanent deformation, and a plurality of axially spaced ribs in the bore of said body portion intermediate the ends thereof extending in circumferentially unbroken relation about said bore and formed integrally with the inner surface of said first-mentioned wall portion, each of said ribs being of a length relatively greater than its radial thickness.

JOSEPH H. I-IOERN. MARTIN D. ARCHANGELI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,338,292 MacMillan Jan. 4, 1934 1,983,735 Corlett Dec. 11, 1934 2,096,092 Dostal Oct. 19, 1937 1,454,084 Short May 8, 1923 1,435,925 Jardine Nov. 21, 1922 1,691,778 McDonald Nov. 13, 1928 1 873.569 Ford Aug. 23, 1932

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