US1700677A - Magneto - Google Patents

Description

Jan. 29, 1929.

l. E. HENDRICKSON MAGNETO '5 Sheets-Sheet 2 Filed Feb. 9, 1927 J ZZ/Z \INVETVTOR. x1 Am A? BY ffl m ATTORNEYS.

Jan. 29, 1929. 1,700,677

7 I. E. HENDRICKSON' MAGNETO Filed Feb- 1927 3 Sheets-Sheet 3 Patented Jan. 29, 1929.

UNITED STATES PATENT A OFFICE.

ERA E. HENDRICKSON, OF WEST SIRINGFIELD, MASSACHUSETTS, ASSIGNOB. TO WICO ELECTRIC COMPANY, OF WEST-SPRINGFIELD, MASSACHUSETTS, A CORPORATION 61 MASSACHUSETTS.

NIAGNETO.

Application filed February ticularly suitable for use in a magneto of the general type set forth in United States Letters Patent No. 1,634,135, granted June 28, 1927, to Phelps Brown. Such magneto is of: two unit type having two recipro.- eating arniatures working substantially in aiternation and the two units are connected so that each contributes to and assists in the work the other.

The improvements of this invention are intended for use in such magnetos and are also capable of use in other magnetos of the reci oocating armature ty e and in certain as the invention can he used equally well single unit magnetos. These improvents also primarily designed and particularly advantageous for reciprocating ariature magnetos which are intended for use w ch nines operating at considerably higher I the stationary engines, with this type of magneto has most ifre- :t uentiy been employed heretofore. For exampie, the magneto, hereinafter disclosed, is l a use with the engines of tractors trucks and is designed to be soc is from MOO to 1800 R. P. M. one service and intermittently at hi -her speeds. The speeds, referred to, intended in any sense as limits. They ntioned merely to illustrate a condihich has to be met in order to adapt a .s. ,iieto of the stated type to new and broader iieids of service. mature actuating mechanisms, funcnally similar to that of this invention so far as or-cad purposes are concerned, have provided heretofore invarious forms. and those are satisfactory for their intended a given prior art type of are -"owever, mature "ctuating mechanism, which opersatisiactcrily in a low speed magneto, not necessarily give satisfaction with a magneto operating at much higher speeds.

The mechanism, quiet in operation at low speeds, become unduly noisy when operat high speeds.

The present invention, in one of its broad aspects, is directed to, and has for an 0036013,

9, 1927. Serial No. 166,825.

the provision of an armature actuating mechanism for a magneto of the type described which will admit of operation at high speeds in a commercially satisfactory manner.

In this connection it is an object of the invention to provide an armature actuating mechanism for a magneto of the type described, which embodies an improved system of levers, whereby a relatively small force applied from the drive shaft will be multiplied during its transmission to the armature so that an adequate and much larger force is available to overpower the resisting force of magnetic attraction and move the armature away from its poles.

An important characteristic of the armature actuating mechanism lies in the avoidance, so far as possible, of im which, while perhaps insignificantin low speed operation, would in high speed operation produce objectionable'noise. Coupled with this characteristic andincident thereto and to the improved leverage system, is the reduction of strains and consequent wear" on the parts of the mechanism. The primary purpose, however, is to render the magneto easy to operate and relatively quiet in operation at the higher speeds.

Another object of the invention relates to the improvement of the operation of a magneto of the two unit type, when working at very low speeds, such as cranking speeds for example,the improvements resulting in the production of a longer and fatter spark from the magneto at cranking speeds than could be produced at cranking speeds from the magneto of said copending application.

acts or blows Another object of the invention relates to I an improved disposition and relative arbricat-ion; and of keeping the dimensions of.

a compact grouping of s I the magneto within standard limits recognized in and demanded by the trade.

There are many details contributing to the accomplishment of the above objects and these, as well as other objects and advantages, will appear in the following description and will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanying drawings, in which Fig. 1 is a front elevational view of a mag neto embodyin the invention,-the casing of the magnet-o being shown in section to reveal the interior;

Fig. 2 is an end elevational view looking from the left hand end of Fig. 1,the casing being shown in section;

Fig. 3 is an exterior end elevational view looking from the right hand end of Fig. 1;

- Fig. 4 is a cross sectional view taken on the line 1-4 of Fig. 1 but drawn to a larger scale' Fig. 5 is a fragmentary cross sectional view taken on the line 5.5 of Fig. 1 but drawn to a larger scale;

Fig. 6 is a sectional elevational view taken on the line 6-6 of Fig. 2 but drawn to a larger scale;

Fig. 7 is a sectional bottom plan view taken on the line 7-7 of Fig. 1 but drawn to a larger scale F ig 8 is a diagrammatical view illustrative of the electrical circuits and connections'of the magneto;

' Fig. 9 is a schematic view showing the control device positioned to effect spring drive of the armature;

Fig. 10 is a detail view, partly in section, of the drive shaft of the magneto;

Fig. 11 is an enlarged detail of one of the driving cams; and a Fig. 12 is a fragmentary cross sectional view taken on the line 1212 of Fig. 6.

In order to best illustrate the many advantages of the armature actuating mechanism of this invention, it has been shown as embodied in a magneto of the two unit ty e having two reciprocating armatures. A ull disclosure of such magneto will be given in order to show the invention in one complete and operable embodiment capable of satisfying the conditions above stated. The invention is not, however, limited to use with the particular magneto disclosed herein for illustrative purposes but is capable of use with many other magnetos of .the reciprocating armature type differing specifically from that disclosed. Neither is'the invention, in all its aspects, confined to a magneto having two ar matures. While such construction is important and preferred, there are many features of the invention, as pointed out in the a pended claims, which are,'or may be, entirely independent of the two armature arrangement.

Referring now to the construction of the particular-magneto, the two units thereof are connected to work in cooperative relation so that each contributes to and assists in, the work performed b the other. These two units are supporte from a common frame, driven from a common drive shaft, utilize a common source of magnetic flux and are controlled both mechanically and electrically by common means. structurally the units are alike. A description of one will therefore suflice for both and the corresponding parts of the second unit will be designated by the same reference numerals primed.

Each unit includes a pair of cores 12 or magnetic pole pieces (Fig. 1) which are vertically disposed in spaced parallel relation and the upper ends of which are connected to opposite poles of a source of magnetic flux, herein exemplified by permanent bar magnets 13. The cores, of course, are built up from suitable laminations in the usual manner except that their upper ends are so shaped as to encompass the polar ends of the magnets and afford oppositely disposed recesses to receive the same. Between the laminations of cores 12 and those of cores 12 (the latter being located in back of but spaced from cores 13) are other laminations 14 (Figs. 2 and 6), which fill the space therebetween, as clearly shown in Fig. 2, and which are shaped correspondingly with the upper ends of the core laminations to afford magnet receiving recesses,-the whole affording two long, oppositely disposed recesses for receiving oppositepolar ends of three stacks of permanent bar magnets. The magnets of each stack are held in place by wedges 15, which are driven in between two adjacent magnets of each stack and thereby force the upper andlower magnets of each stack firmly against the ends of the receiving recesses in the laminations. The laminations of cores 12 and 12 and the laminations 14 are suitably clamped together, as by a series of bolts 16. These bolts also act to secure opposite ends of non-magnetic cross bars 17 and 17 (Figs. 1 and 6) to the upper ends of cores 12 and 12, and these cross bars serve to hold the cores of each set in proper spaced relation. The lower ends of the cores, as shown in Figs. 1 and 7 are received in recesses formed in a horizontally disposed'frame member 18 and are clamped in such recesses by screws 19. The cores extend downwardly a short distance below frame 18 and their bottom faces, which constitute magnetic poles, are adapted to be intermittently connected and disconnected by a reciprocating armature 20.

Each unit also includes two primary coils 21 (Figs. land 7) encompassing each core 12, and two secondary coils 22, one encompassing each coil 21. The coils 21 and 22 and the corresponding coils 21and 22' are housed in recesses formed in a common block 23 of bakelite or other similar or suitable material, which block fitssnugly between frame 18 and the cross bars 17. The primary coils,

21 may be connected in any suitable way to function as one choke winding. As shown in Fig. 8, they are connected in electrical series by a wire 24. The two choke windings, comranged in upper and lower pairs.

prising the connected coils 21 and .the connected coils 21 are controlledby a single interrupter, comprising relatively movable breaker points 25 and 26. One terminal of each choke winding is grounded, as indicated in Fig.8, and the point 25 which, as will appear, is in contact with metallic parts of the machine, is likewise grounded. The other terminal of each choke winding is connected by a wire 27 to the breaker point 26, which as will appear is insulated from the metallic parts of the machine. A condenser 28 is provided, one terminal of which is grounded and the other connected by a wire 29 to breaker point 26.

The secondary coils 22, constituting the generating winding, are suitably connected, as in electrical series. by a wire 30 and the two generating windings, comprising the connected coils Q2 and the connected coils 22' are connected in any suitable way so that the currents simultaneously produced in each are merged. As shown, the two windings are connected in series by a wire 31 so that the electromotive force producedin each is added. The terminals of the generating winding are connected to a suitable distributor D, which functions to successively connect the generating winding at properly timed intervals to a series of spark plugs s.

The distributor, illustrated herein; involves an insulating panel 82 (Fig. 6) which is secured to one end of frame member 18 and carries four contacts 33 (Figs. 1 and 6) ar- An insulating arm 34, pivoted to frame 18 at 35 (see also 8), oscillates back and forth between these pairs of contacts and carries conducting pieces 36 and 37 which simultaneously engage one contact of each pair. The two terminals of the generating winding are thus successively connected to pairs of spark plugs but the plugs of each pair are arranged in series and one of them produces a spark on the firing stroke while the spark produced by the other occurs near the endof the exhauststroke. An insulating block 38, held in place by the casing C of the magneto, encompasses the contacts 33 and has sockets to receive the spark plug wires 39. Block 38 carries springs 40 to connect such wirest-o the contacts 33. The construction and operation of the distributor is not essential to the present invention and is herein shown and briefly referred to merely to complete the description and disclosure of the ignition apparatus. 1

The interrupter, referred to, is mounted near that end of the machine opposite from the distributor. The interrupter is supported from the center of a cross bar 41 (Fig. 5) which in turn is supported near opposite ends, through the intermediary of spacing sleeves 42, from posts 43, which are formed integrally with an upstand from member 18. Screws 44, passing through bar 41 and sleeves 42, are threaded into posts 43 and serve to clamp bar 41 thereto. The central portion of bar 41 has an opening therein into which a bushing 45 is tightly driven. This bushing slidably receives a tubular interrupter casing 46, which is provided exteriorly with upper and lower flanges 47 and 48. A spring wire 49, secured at .its ends to bar 41 by the screws 44 described, is bent so as to afford two legs, which extend vertically upwardly from the bar onopposite sides of casing 46, and a connecting horizontally disposed portion, which is coiled around the casing. Upon this coiled portion rests the upper flange 47 of the interrupter casing, whereby the latter is yieldingly urged upwardly into the illus* trated position. It can be moved downwardly, when required, against the tension of spring 49 by means later to be described, which means engages the lower flange 48 of the casing 46 anc serves to control the vertical position of the latter.

The upper end of casing 46, which is closed serves to support the breaker point 26,the latter being adjustably fixed to and insulated from said end. The other breaker point 25 is fixed to the upper end of a plunger-50, which slidably fits the bore of casing 46. The plunger 50 is adjustably fixed to a threaded stem 51 and the lower end of the latter has a flange 52 (Fig. 6) which rests upon the free end of a fiat spring 53, secured to frame member 18 as shown in Fig. 6 and tending to move plunger 50 upwardly.

Referring now to the armature operating mechanism, with which this invention is primarily concerned, the armature 20 is fixed by bolts 55 (Figs. 1 and 7) to an arm 56. These same bolts also serve to fasten a plate 57 to arm 56,-such plate serving to operate breaker point 25 as will later appear. The arm 56, at one end, is pivotally mounted on a stud 58, which is fixed to a post 59 located beyond one end of armature 20. This postdepcnds centrally from frame 18 and serves to support one end of the latter from, and in spaced relation with, a base plate 60. The other end of frame 18 is supported from base plate 60 by an end frame 61, which is secured by screws 62 (Fig. 2) to said end. The armature hinge arm 56 extends along the inner side face of its armature and well beyond the opposite end thereof. The two arms 56 and 56 he adjacent and in spaced parallel relation except for their free ends which are offset outwardly and terminate with parallel c lindrical ends 63 and 63. Such ends are isposed closely adjacent the endframe 61.

Both the armature hinge arms 56 and. 56' are operated from a common drive shaft 65, which is disposed between and slightly above these arms. The shaft 65 is rotatably mounted and adapted to be driven from an internal combustion engine in proper timed relation therewith. In this particular case, it is adapted to be driven at crankshaft speed from a four cylinder, four cycle engine. The shaft near one end has a bearing of ample diameter and length in the end frame 61 (Fig. 6), and near its other end has a hearing in the post 59. A collar 66, fixed to shaft 65, engages the outer end face of the first named hearing and serves to take any inward end thrust occasioned by the coupling (not shown) by means of which shaft is connected to the engine. The shaft extends beyond post 59 and carries a cam 67 to actuate the distributer arm 34, hereinbefore referred to. The shaft 65 is provided with two cams 68 and 68 for operating the hinge arms 56 and 56 respectively. These cams are preferably made up of steel laminations, as indicated in'Figs. 6 and 10, because a certain degree of desirable resiliency is obtained thereby and because of economy in construction. The laminated construct-ion of the cams also helps, in so far as lubrication is concerned, because oil will be held between the laminations and will more readily cling thereto than to the smooth periphery of a solid cam. The shaft 65 is, for convenience, made in three sections as shown in Fig. 10, the sections a and I) being joined by a sleeve section 0, in which the other sections are secured by a drive fit. The laminations are clamped between a flange on section a and one end of sleeve 0. These cams are alike but arranged in diametrically opposed relation on shaft 65 Fig. 4). They are also spaced one from the other longitudinally on this shaft, although both are arranged in close proximity and in close proximity to-elid frame 61 (see Fig. Each cam has adwell portion d of substantial angular extent. In the example shown, the dwell portion- "'tis approximately 140 degrees in angular ex-, tent. The remaining portion of the peripl i,;.

cry of each cam is made up of a rise portion 0 and a drop portion f', the sc two portions gradually merging together and-each gradually merging with the dwell portion d. The cam construction will be later considered in further detail but for the present it will suffice to state that the active portions of cams 68 and 68 are opposed --s otliat,.while one cam is functioning to move its armature away from its poles, the other cam permits the other armature to move backtoward and into contact with its poles. ,...The armatures 20 and 20' thus wort: substantially in alternation although not in exact alternation.

The armatures may be moved in their flights away from their poles in either of two ways. First, they may be moved entirely by an inelastic transmission of force from their cams 68 and 68. Second, they may be initially moved a very short distance away from their oles in this manner (to pry the armatures loose from their poles and break the magnetic hold) and thereafter be moved the remaining distance by the expansive action of previously stressed elastic means.

The inelastic transmission is effected by the following mechanism. A lever 69 (Figs. 4 and 7) is mounted intermediate its ends to turn freely on the cylindrical end 63 of the armature hinge arm 56. A cam follower, comprising an arcuate flange 70 bent out wardly at right angles from the free end of an S-shaped arm 71 of metal plate, is interposed between one end of lever 69 and its cam 68. The follower arm 71 is pivotally mounted on a stud 73 (Figs. 4 and 7) secured to a lug 74: on frame 61. In the case of the follower 71, the pivot stud 73 is secured to a post 75, which depends from frame 18 (Fig. 7). The lever 69, at its. other end, is provided with an adjustable abutment in the shape of a screw 76 (Fig. 4), designed to bear against the lower end of a pin 77, which is mounted to slide freely in av rig-78 formed on frame 18. An armature return spring 72, (Fig. 1) interposed between armature 20 and base plate 60 tends to hold the armature to its poles and thus tends to raise the hinge arm 56 and the lever 69 carried thereby, whereby the lever 69 is lifted, one end being caused to bear on pin 77 and the other end being caused to bear on follower 70, thereby urging the latter toward its cam 68.

The pin 77 may be held against upward movement, beyond the illustrated position or, by adjustments to be described, it may be held against upward movement beyond tain other and higher vertical positions. When this pin 77 'is held from moving upwardly beyond the illustrated position, a

direct or inelastic drive of the armature 20 ""from cam 68 results. Thus,,the pin 77 forms a fulcrum for lever 69 and, as the free end of the latter is depressed by cam 68, the hinge arm 56 is lowered and armature 20 is pried off its poles, to which it was theretoforc held by the strong force of magnetic attraction. and moved away from its poles the required distance.

In order to hold the fulcrum pin 7 7 against upward movement beyond the illustrated po-- sition, or beyond various other and higher vertical positions, a cam 79 is arranged to bear on the upper end of pin 77, as shown in Figs. 1 and 4. This cam and the cone spending cam 79 are fixed to a shaft 80 near opposite ends thereof. This shaft, which (BX- tends transversely across frame 18', is seated in semi-circular bearings formed in the upper ends of the described posts 43 and located forwardly of cross bar 41. It is held in each of these hearings by a strap 81, one end of which underlies the cross bar 41 (Fig. 6) and is upturned to bear against the same as a fulcrum. The strap 81 passes across the top of shaft 80 and-its other end is drawn down- It will be noted that the cams 79 may be turned throughout a certain range (through the angle as shown in Fig. 9) without permitting a change in the vertical position of the fulcrum pins 77 and 77. If moved beyond this range, the cams will permit these pins to be raised. to various higher positions.

When the cams are positioned to permit thelast mentioned condition, the movement of the armatures away from their poles, after the preliminary prying off of the armatures by the inelastic transmission of force described, is effected by the expansive action of previously stressed elastic means. To secure this action, a drive spring 84 is interposed between a rearwardly offset lug 85 on lever 69 and an abutment 86, adjustably secured to cross bar 41 (Figs. 1 and 5). The abutment 86 has a long depending guide 87 extending into the spring to restrain it from undue transverse flexure and the abutment 85 has a projection 88 entering the lower end of the spring. It will be seen that, if pin 77 is free to rise above the illustrated position, the first action following the depression of cam follower by cam 68 will be to tilt lever 69 about the cylindrical end 63 of the armature hinge arm as a fulcrum. This follows be-.

cause the armature is held firmly to its poles by magnetic attraction and because the pin 77 is free to rise. Thus, the outer end of lever 69 is raised and the drive spring 8i is thereby placed under stress. This drive spring, even when stressed as much as possible with the illustrated arrangement,is insufficient to over come the force of magnetic attraction which holds the armature to its poles. Consequently, the stressing of the drive spring continues until the pin 77 is arrested in its upward movement by cam 79. Then pin 77 functions as before as a fulcrum for the lever 69 and the armature is pried off its poles by the described inelastic transmission of force from cam 68. Immediately following the prying oil' of armature 2O from its poles. the magnetic attraction'on the armature 1s so diminished by the creation of even a very small air gap betweeuthe armature and its poles, that the previously stressed drive spring 84. is enabled tomove the armature and more rapidly than it would be moved by cam- 68. Consequently, spring 84 expands and, since the inner end of lever 69 bears on cam 68, the latter temporarily serves as a fulcrum therefor, while the lever and thus the armature 20 is being moved by the expanding drive spring.

It will be obvious that the degree of stress ing of the drive spring may be varied according to the position of pin 77, being greater if the in is allowed to rise higher. It will also be 0 vious that the time when the armature leaves its poles with relation to the angular position of shaft 65 may be varied by the setting of pin 77. When the latter is positioned as illustrated, the armature leaves its poles at an earlier position in the revolution of shaft 65, or in what may be termed full advance position. If, however, the cams 79 be so set as to allow the pins 7 9.to rise above the illustrated position, the armature leaves its oles at a later time in the revolution of sha't 65, or in what may be termed retard v position. The production of a spark from- Y the magneto depends on the tinie of separation of the breaker points 25 and 26 and such separation is effected by the movement of armature 20 and normally occurs after the armature has moved a certain distance away from its poles. Consequently, with the described arrangement, a retarded spark is produced from the magneto when spring drive.

is used and 'this is the desired condition for the spring drive is intended to be used primaril when the engine is started. B the use 0 other means, later to be describe the point in the downward flight of the armature at which the breaker points open ma be varied'so that it is possible, should such a condition be desired to arran e for advanced spark when spring drive 0 the armature is used.

The mechanism for separating the breaker points 25 and 26 will now be described with particular reference to Figs. 5,6 and 7. The plates 57 and 57 heretofore described as fixed to the armatures'20 and 20', extend beyond their armatures (to the left as viewed in Figs. 6 and 7) and the free end of each is given a quarter turn, thereby forming a horizontally disposed lug 90. Passing freely through the lugs 90 and 90, as best shown in Fig. 5, are screws 91 and 91' which are disposed on opposite sides of shaft 65. These screws also pass freely through a lever 92, one near each end thereof, and are supported from the lever by their heads which rest on crimped portions of the lever. This lever 92 encompasses the described stem 51 and cen-- trally betweenits ends is fulcrumed on the upper face of flange 52. The lever 92 is crimped at its middle to afford substantially lock nuts 94 and 94 to hold the abutments in their adjusted positions.

The arrangement described permits the one interrupter to be operated alternately by the two armatures. As armature 20' left 5 all slack in the connections is taken up its poles to reach the illustrated position the lug 90 eventually came into engagement with abutment 93' and tilted one end of lever 92 downwardly about its central crimped portion as a fulcrum, thus raising the other arate breaker point 25.from breaker point 26.

The raised end of lever 92then served as a fulcrum, bearing on the head of screw 91. The arrangement is such that the points 25 and 26 are separated at an intermediate point in the flight of armature 20' away from its poles. As armature 20' moves back toward its poles,.the spring 53 causes the points 25 and 26 to be again engaged and just as the armature 20 is about to seat on its poles 12', the armature 20 starts to leave its poles 12. The armature 20, in its flight away from its poles, causes lug 90 to engage abutment 93 and tilt the righthand end oflever 92 (Fig.

downwardly, raising the other end unti an thereb depressing flange 52, with the raised end 0 lever 92 bearing as a fulcrum on the head of screw 91'. Thus, the armature 20 also serves to separate the breaker points at an intermediate point in its downward movement. By suita le adjustment of the parts, the breaker points are caused to separate at the optimum point in the downward flight of each armature.

It has been shown heretofore wherein a change in the timing of the sparks from the magneto may be effected by changing the positions of cams 79 and 79', whereby the armature is caused to leave its oles at later times when spring drive is use for the armature than when the latter is directly driven. It is often desirable to vary the timing when direct drive is used for the armature and for such purpose means are provided for varying the vertical position of the up or breaker point 26. Such means are pre erably controlled from shaft 80 and, as shown in Figs.

4 and 6, a cam 95 is formed integrally with and on the central portion of shaft 80. Cam 95 is adapted to engage a rocker arm 96 pivotally mounted on a pin 97. Pin 97 is secured at its ends in laterally spaced depending ears formed on a washer like piece 98 which is held in place between the lower face of cross bar 41 and the flange of the described bushing 45. The inner end of rocker arm 96 straddles the interrupter casing 46 and bears against the flange 48. Consequently, when arm 83 is so turned as to cause cam 95 to lift the outer end of rocker arm 96, the inner end thereof forces flange 48 downwardly and causes breaker point 26' to be lowered. The lowering of point 26 naturally causes a later disengagement of point 25 therefrom. As I of the fulcrum pins 77. Therefore, the spark can be advanced or, retarded while the cams 7 9and 79, are set for direct drive of the ar- .mature, these cams having dwell portions Corresponding in angular extent to that necessary to move cam 95 to cause a lowering of breaker. point 26 throughout its entire range of movement. This range is sufficient to give all the'spark control that is desired, from full advance to full retard and is designed to provide for a retarded spark which is at least as late as that obtained when spring drive is used.

When shaft 80 is turned from the position 6 shown in Fig. 1 throughout the angle w (designated in Fig. 9) the upper breaker point 26 is moved from its highest vertical position downwardly as far as possible. Of course, this range of movement can readily be changedin degree and could even be reat enough to prevent any separation o the breaker points by the armatures if that condition should be desired for any reason. If the shaft 80 is moved counterclockwise, as viewed in Fig. 9, back through the angle a: the upper breaker point 26 is restored to its original position, which is such as to. cause the separation of the breaker points to occur at the optimum point in the downward flight of each armature. This optimum point for direct drive of the armature is in this case slightly different from the optimum point when the armature is moved by spring drive. Accordingly, the cam 95 is so constructed as to properly position the upper breaker point 26 to permit separation of the breaker points at a slightly different point in the downward flights of the armatures when the latter are moved by the spring drive. When cam 79 has been turned clockwise from the position shown in Fig. 1, through the angle :21, the

highest point of the cam 95 bears on the rounded left hand end of the rocker arm and provides the full retarded spark for direct drive of the armature. If, now, the spring drive is to be used, the shaft 80 is turned still further in a clockwise direction into a position such as shown in Fig. 9, or still further 1 one side of the cam is wider than the other be produced arm 96 from rising so far as it could if cam 79 was positioned as shown in Fig. 1. Thus, the maximum vertical position of breaker point '26 is different when spring drive is used than when direct drive is used. The difference is not very great but it is nevertheless very important because it allows the spark to at the most favorable point in the downward flights of the armatures with each form of drive. Except for the arrangement described, the separation of the breaker points would have to occur at the samepo-int in the downward flight of each armature, re-

gardless of which form of drive is used, say

at some point which is a compromise between the point which is most favorable when spring drive is used and the point which is most favorable when direct drive is used. The described arrangement avoids any such comprise and permits the best results to be obtained with each form of drive.

The general operation of the magneto-will pow be described. As shaft 65 is revolved 'rst one and then the other armature is moved. Each armature moves through one cycle, that is, away from its poles and subsequently back into contact therewith, during a little more than a half revolution of shaft 65 and dwells on its poles during the remainder of said revolution. These cycles occur in alternation so that two sparks are produced during each revolution of shaft 65 at symmetrical intervals. Thus, the magneto, when shaft 65 is driven at crankshaft speed, will produce the ignition sparks necessary for a four cylinder, four cycle engine,the ignition E. M. F. from the magneto being distributed at proper intervals successively to the several cylinders by the distributer D, as above described. As one armature, say 20% moves away from its poles, the reluctance o itsmagnetic circuit is greatly increased and when the breaker points 25 and 26 separate, the choking winding 21, which has theretos fore tended to restrain a change of flux, is opened and a sudden change of flux results thereby generating an F. in coils 22-. As the other armature 20 moved toward and into contact with its poles (such contact occurring with either drive shortly after armature 20 has left its poles), the reluctance of the magnetic circuit of which armature '20 is a part was also changed although a flux change was, to a large extent, restrained because the choke windings 21' were short circuited during the latter part of the return travel ofarmature 20. The separation of breaker points 25 and 26 serves, as will be seen from Fig. 8, to open both the choking windings 21 and 21 so that two flux changes, one due'to the downward movement of armature 20 and the other due to the upward movement of armature 20, are produced and, by reason of the common control through the one set of breaker points, these two flux. changes-are. made to simultaneously produce two E. M. v F.s,-one in windings 22 and the other in windings 22. These generating windings are interconnected, as described, so that the two E. M. F.s are merged. As shown, they are added so that a better spark is produced by the two cooperating units than could be obtained with either when working separately.

Considering the armature actuating mechanism in more retail and referring to it also in connection with Fig. 11, it will be noted that the rise portion 0 of cam 68 is peculiarly formed. It starts with a slow gradual rise, indicated by the are 9 and is followed by a quick sharp rise it. Near the endof the rise portion 6 is a part '5, over each increment of which the rate of change of rise is constant.

While there is a continuous rise over the entire angular extent of portion 6, the rate of change for equal angular increments varies. Throughout the angle g, the rate of change is small but gradually increasing. This c0nstruction enables the armature to be removed slowly from its poles. Consequently, this heavy duty work is accomplished without a shock or blow. WVith direct drive the arma ture starts to leave its poles when the cam follower rides onto the very beginning of the initial portion 9 of the rise e and it is accelerated, at first by small increments and then by very much larger increments, so that the cam follower begins to acquire appreciable speed as it rides onto the art h. By reason of the part h, the cam fo lower is accelerated still more rapidly and the armature then acquires what may be called tri speed. That is, it gets to moving rapidly enough so that the speed condition is favorable for opening the breaker points. This speed is acquired at a time when the arm-a ture is separated an appreciable distance from its poles so that the air gap condition is likewise favorable for opening the breaker points and suchaction then ensues. With direct drive, the breaker points open at. about the time when the cam follower has reached the end of the part it of rise 6. The spark, having been produced by the opening of the 1 breaker points, further downward movement of the armature by cam 68 does not affect the electrical o eration of the magneto and the cam can an does continue to lower the armature still further,-finally permitting it to-return to its poles under the action of spring 72. Thefinal part of dwell portion f is so fashioned as to cause the armature to slow drive spring and the armature is not moved until the cam follower rides onto the portion 2' of the cam. This portion, as described. has a constant rate of rise for equal angular increments so that the tripping of the armature, although varied by the adjustments de scribed so as to occur at different points over the range of portion 1' will always occur under similar conditions. The movement of the armature under the action of the drive spring 84 is exceedingly rapid but there is some lag even in such a rapidly operating member and, on this account, the rise of the cam is continued beyond the latest point at which the spring action can be initiated. This extension of the rise (that portion between the portions '5 and is provided for insurance. It positively prevents the armature from moving back'until the drive spring has moved the armature far enough to cause a separation of the breaker points. In other vwords, the cam follows along behind the spring for a certain time and insures against any possible trouble from the source mentioned.

The return spring 72 need not necessarily be arranged to move the armature all the way back into contact with its poles. It will sufiice if the return spring moves the armature far enough back toward its poles so that it can be drawn into contact therewith .by magnetic attraction. Also, it is possible to eliminate the return spring and rely entirely on the breaker point spring, which tends of course to lift each armature.

A novel and important feature of this invention consists in the provision of means for arresting each armaturein its return flight toward its poles and preventing the same from contacting with such poles while the other armature is in contact with its poles. The provision of such means is useful and important when the armatures are being operated by spring drive. Such means is not necessary and does not function when the armatures are being operated. by direct drive.

' By reference to Fig. 11, it will be seen that when one cam follower, as 70, is riding on dwell portion d of its cam 68, (the condition necessary to permit armature 20 to contact with its poles) the other cam follower 7 0- will be riding on a diametrically opposed part of its cam 68 and thus on either the rise portion 6 or the fall portion f. Consequently, with direct drive. both armatures cannot be in contact with their respective poles at the same time. When, however, the armatures are being operated b spring drive, it would be possible, except or the provision of the means above referred to, for both armatures to be in contact with their respective poles at the same time. Recalling that with spring drive, one armature, as 20, does not leave its poles until its cam follower 70 reaches the part i of its cam 68, it willbe apparent from.

Fig. 11 that the other cam follower 70 will then be ridin on the diametrically opposed portion, viz, tie dwell portion (Z of cam'68, whereby the annature 20 would, unless prevented by splecial means, he in contact with its poles. vcn with a condition of this kind, the magneto will operate satisfactorily enough for a great many classes of service but, bearing in mind that the magneto of this invention is intended for use on tractors, which have to be started by cranking and often in very cold weather, it. becomes most important to provide for the production of the best pos sible spark for use in starting under these severe conditions. I have found that the'operation of the magneto under spring drive is very greatly improved and that a longer and fatter spark results if one armature on its upthrow stroke is held away from its poles until the other armature starts to leave its poles. The desired result is to reproduce with spring drive operation the same general conditions as obtain with the direct drive operation, as hereinbefore-described.

The particular expedient illustrated for accomplishing the desired object consists of a cross bar 101 which, as best shown in Fig. 12, is supported at opposite ends by resting on the top edges of the armature hinge arms 56 and 56 and extends across from one to the other, passing beneatlrthe drive shaft 65. As will be apparent from Fig. 12, when the armature 20 moves upwardly toward its poles it will raise the left hand end of bar 101 until the latter engages the drive shaft 65'(or any other suitable abutment for that matter) and thus arrest the armature 20 until armature 20 is moved out' of contact with its poles. The particular expedient shown has been chosen primarilyasa simple way of illustrating the essential idea. This expedient is doubtless capable of refinement and various other expedients, differing in detail from that shown, will doubtless occur to those skilled in the art. The details are not nearly so important as theresult pointed out herein. I point out, however, that it is desirable to keep the cross bar inplace both laterally .and longitudinally on the hinge arms 56 and The disadvantage in allowing both a-rma tures to contact with their poles at the same time is that one tends to shunt some of the magnetic flux from the other. In Fig. '12, armature 20, which has been dwelling on its urpose of allowing flux to build netic circuit of which it'is a. 1, especially in very low speed robbed of some flux if the armaie into contact with its poles bee had moved away from its niountered because the time eleindings will rcuits over short intervals. The 'ntcrval, however, the less effective ng influence of the choke windequently, although the breaker gaged and the choke windings ed, when armature 20 apely to its poles, this armature sieving relatively slowly, as at ls, rod flux from the Other aroat is my theory of the action. s have proved by experiment, b longer and fatter spark can th spring drive operation of -s magneto when the cross bar 101 is used a 'thout it. The result is most imporg a large, fat spark for insurnition at cranking speeds even old weather.

ower 70 and its integral supsequence. Such, however, is hese elements are important .y save the armature hinge arm y lateral strains to which it we be subjected. As the cam d commences to depress the also exerts a lateral thrust this case is transmitted 71 to the stud 73, secured to une. In this way, the burden '"zirust is taken by the cam folthe desired downward mo- .-icated to lever 69. This is because the armature hinge I a point remote from that is located. Consequently, a E ermitted on lever 69, would through arm 56 as a long art considerable strain thereon. e arm 56 would, by reason of e free to move sidewise to some e lateral thrust and such conesired. 76 also has its importance. It the up all slack in those parts of actuating mechanism which the armature is driven solely The motive is to keep all ct and avoid all noise-producents during normal operation 0. It is contemplated that the be operated for the most part e,-the spring drive usually beparticularly for starting. The

wi l

so 1 a speed op eration,less difiiculty ll may, at first glance, appear to small force applied at the drive shaft.

magneto operation under direct drive. The

slack in the driving connections is taken up as follows ;eam 79 is first moved into proper position for direct drive and then screw 76 is turned until pin 77 has been raised into contact with cam 79, after which the screw is turned still further until lever 69 is engaged with cam follower 70 and the latter is moved into contact with cam 68. This screw can also be utilized for another purpose, viz, to prevent contact of the armature with its poles, if and when desired. If the screw be turned still further in the same direction after all the slack in the operating connections has been taken up, the armature can be removed from its poles. In this way, the upward movement of the armature, when operated by direct drive, can be limited so that contact between it and its poles is prevented. A very slight air gap may thus be created, instead of a condition of actual contact, between the armature and its poles.

By the particular armature mounting chosen, wherein the hinge arm extends longitudinally rather than crosswise of the armature, a powerful leverage is available. A longer hinge arm can be used than would be feasible if the arm extended crosswise of the armature because space limitations are such that more length than width is available. The fulcrum of the hinge arm can be-located beyond one end of the armature and just far enough beyond this end to admit of sufiicient separation between the armature and the ad jacent core] The force is applied to the free extremity of the hinge arm at a point well beyond the opposite end of the armature, so that such force removing the armature from its cores. The lever 69, by means of which the actuating force is applied to the free end of hinge arm 56, also serves to multiply the force applied to it, whether that force is applied by the cam 68 or by the drive spring 84:. In either case, the force is applied to one end of the lever and the fulcrum of the lever is at the opposite end, while the load is, as shown, in the center. The force applied to lever 69 is therefore doubled (and it might be still further increased if necessary or desired) when applied to hinge arm 56. Consequently, a system of multiplying levers is-available for the purpose of performing the heavy duty of prying the armature off its poles with a relatively t follows that the latter can be turned with comparative ease, even by hand. It also follows that if the shaft can be easily turned in this manner that there is an absence of severe blows and shocks in operation. The underl ing reasons for this have been explained above in connection with the construction of cam 68. It need onlybe' stated is multiplied for the work of i here that the magneto operates with surprising quietness even at high speeds, such as those above referred to, and this is a new accomplishment in a magneto of the reciprocating and contacting armature type.

Another important feature relates to the disposition and relative arrangement of parts of the armature actuating mechanism. The arrangement disclosed is characterized by compactness and the eflicientutilization of substantially all available space between the base and the plate-like member 18. i The [arrangement likewise permits, in a magneto having two armatures, the grouping of the two drives at one end of the machine. Both cams 68 can be located close to the large main bearing in the end frame 61 and only a small part of the shaft, as shown, need be of large diameter. The remainder of shaft 65 is not subjected to any material torsional strain because it simply serves to drive the distributer arnr 34. The shaft is not extended beyond cams 68 and 68 solely for this pur ose, however. Where. as here, it is not easible'to get an ample bearing on each side of the cams, and closely adjacent thereto, the condition imposed is that of using cranks overhanging from one bearing. This conditionnormally is poor but by the use of a long extension of the shaft, supported as shown at a point remote from the cranks, a long leverage is ob tained to prevent lateral deflection of the shaft in its main hearing. A smaller main bearing can be used than would otherwise be the case and the bearing is saved from much of the wear to which it would otherwise be subjected.

To meet existing standards recognized in the trade, such as those set, for example, by the Society of Automotive Engineers, it is necessary to keep the height and width of the magneto within certain limits. It is also necessary that the center of the drive shaft be located a fixed distance from the bottom of baseGO. The present magneto meets these standards and largely because of the disposition and relative arrangement of parts of the armature actuating mechanism. To keep down the height of the magneto, the space between the frame members 18 and 60 has been reduced to a minimum. The space shown is thatnecessary for the armature movement plus some additional space for an adequate return spring. It will be noted that spring 72 has been let into base 60, as far as is feasible to'save vertical space. There is not room above or below the armatures for driving mechanism or any substantial part thereof. Consequently, the armature hinge arm has been fixed to one side face of the armature and extends beyond one end thereof for connection to other parts of the mechanism. The cams, the centers of which must, to satisfy existing standards, be fixed in height, are located beyond said end of the armature where vertical height is available. With the two unit machine, the distance between the cores 12 and 12' is the limiting condition so far as width is concerned. These have been placed as closely together as possible. This results in a certain free space between the armatures and such space has been substantiallly filled, as will be evident from Fig. 7 by the drive shaft, the armature hinge arms, and the operating arms 57 and 57 for the interrupter.

The particular relative arrangement of parts is thus important in that it not only enables a desirable system of multiplying levers to be used, whereby but a small force is required at the drive shaft for operation of the magneto, but it is also important for the reason that it enables certain arbitrary standards set by the automotive industry to be met by a reciprocating armature type of magneto, whereby the latter type is rendered suitable in one respect for a new field of service. In another and most important respect, the magneto is rendered suitable for this new field of service by reason of the improved actuating mechanism which admits of commercially satisfactory operation at the high speeds required and at speeds much higher than those heretofore attempted with a magneto of this type.

The invention has been disclosed herein, in an embodiment at present preferred, for illustrative purposes but the scope of the invention is defined by the appended claims rather than by the foregomg description.

What I claim is:

1.;In a magneto, of the type wherein an armature is moved into and out of contact with its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a pryingoff of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole pieces, comprising, a lever extending generally crosswise with respect to the armature, a pivotal support for said lever engaging the latter intermediate its ends and rigidly connected to the armature to move with the'same, inelastic means for transmitting to one part of said lever a driving force and a member for engagement with another part of said lever and serving as a fulcrum therefor.

2. In a magneto, of the type wherein an armature is moved into and out of contact with its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a prying off of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole pieces, comprising, a lever extending generally crosswise with respect to the armature, a pivotal support for said lever engaging the latter intermediate its ends and rigidly consame, inelastic means for transmitting to one part of said lever a driving force, a fulcrum member disposed in the path of another part of said lever, and means whereby the position of said fulcrum member may be varied to vary the time at which the lever is effective to pry the armature off its pole pieces.

'3. In a magneto, of the type wherein an armature is moved into and out of contact ith its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a prying off of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole pieces, comprising, a lever extending generally crosswise with respect to the armature and having a pivotal bearing carried by movable with the same, inelastic means transmitting to one part of said lever a driving force, a fulcrum member disposed in the path of another part of said lever, means whereby the position of said fulcrum member may be varied to .vary the time at the lever is effective to pry the armature off its pole pieces, and resilient means engaging said lever and capable of being stressed by movement of said lever preliminary to the prying off of said armature and efiective thereafter to move said lever and c to complete the flight of the latter away i its pole ieces. I

4. T i a magneto, of the type wherein an armature is moved into-and out of contact with pole pieces and wherein the flight of the mature'away from its ole pieces is initiated by s prying off of tie armature by an remission of force thereto, mechrying the armature 01f its pole mechanism comprising, a lever generally crosswise with respect to r and having a pivotal bearing i movable with the same, in-

driving force, a fulcrum member i the path of another part of said he whereby the position of said ful- Th9? may be varied to vary the time he lever is efiective to pry the armapole pieces, and resilient means aid lever and capable ofbeing iy movement of said lever prelimihe prying oif'of said armature and er ctive thereafter to move said lever and arms'ure complete the flight of the latter sway om pole pieces, said fulcrum membeing movable to a position wherein said is ineffective to cause movearmature. magneto, of the type wherein an ure is moved into and out of contact ole pieces and wherein the flight of more away from its pole pieces is d by a prying off of the armature by transmission of force thereto,

' its mechanism for prying the armature ofi its pole pieces, said mechanism comprising, a lever extending lengthwise of the armature and connected thereto for moving the same and extending beyond opposite ends thereof, a pivotal support for said lever located beond one end of the armature, a second lever pivoted to the first lever and extending substantially crosswise thereof at a point beyond the other end of the armature, inelastic means for transmitting a driving force to one part of said second lever, and a fulcrum member disposed in the path of another part of said second lever.

6. In a magneto, of the type wherein an armature is moved into and out of contact with its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a prying off'of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole pieces, said mechanism comprising, a lever extending lengthwise of'the armature and connected thereto for moving the same and extending beyond each end thereof, a pivotal support for said lever located beyond one end of the armature, a second lever pivoted to the first lever and extending substantially cross-wise thereof at a point be yond the opposite end of the armature, inelastic means for transmitting a driving force to one part of said second lever, a fulcrum member disposed in the path of another part of said second lever, and means whereby the position of said fulcrum member may be varied to va the time at which said secondlever is effective to pry the armature off its pole pieces.

7. In a magneto, of the type wherein an armature is moved into and out of contact with its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a prying off of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole pieces, said mechanism comprising, a lever extending lengthwise of the armature and connected thereto for moving the same and extending beyond each end thereof, a pivotal support for said lever located beyond one end of the armature, a second lever pivoted to the first lever and extending substantially crosswise thereof at a point beyond the opposite end of the armature, inelastic means for transmitting a driving force to one part of said sec ond lever, a fulcrum member disposed in the path of another part of said second lever, means whereby the position of said fulcrum member may e varied to vary the time at which said second lever is effective to pry the armature ofi its ole pieces, and resilient means capable of eing stressed by said second lever preliminary to the prying off of said armature and effective thereafter to move oft the second lever and thus the armature to complete the flight of the latter away from its oles. 1 P 8. In a magneto, of the type wherein an armature is moved into and out of contact with its pole pieces and wherein the flight of the armature away from its pole pieces is initiated by a prying off of the armature by an inelastic transmission of force thereto, mechanism for prying the armature off its pole, pieces, said mechanism comprising, a lever extending lengthwise of the armature and connected thereto for moving the same and extending beyond each end thereof, a pivotal support for said lever located beyond one end first lever and extending substantially crosswise thereof at a point beyond the opposite end of the armature, inelastic means for transmitting a driving force to one part of said second lever, a fulcrum member disposed in the path of another part of said second lever, means whereby the position of said fulcrum member may be varied to vary the time at which said sec- 0nd lever is effective to pry the armature off its pole pieces, and resilient means capable of being stressed by said second lever preliminary to the prying off of said armature and effective thereafter to move the second lever and thus the armature to complete the flight of the latter away from its poles, said fulcrum member being movable to a position such that said resilient means is rendered ineffective to cause movement of the armature.

9, In a magneto, of the type'wherein an armature is moved into and out of contact with magnetic pole pieces, a lever, a pivotal support therefor carried by said armature, means for applying a driving force to said lever to turn the same on said support as a fulcrum, and means in the path of said lever efi'ective to arrest the lever and temporarily serve as a fulcrum therefor, thereby to enable the lever to pry the armature off its pole ieces.

10. In a magneto, of the type w erein an armature is moved into and out of contact with magnetic pole pieces, a pivotal support carrie by said armature, a lever mounted to turn on said support and extending in a direction generally transverse with respect to the armature, means tlt'er applying a driving force to said lever to turn the same on said support as a fulcrum, and means in the path of said lever effective to arrest the lever and tem porarily serve as a fulcrum therefor, thereby to enable the lever to pry the armature off its pole pieces.

11. In a magneto, of the type wherein an armature is moved into and outvof contact with magnetic pole pieces, a lever, a pivotal support for the lever carried b the armature, a drive shaft, means operable by the latter to effect an inelastic transmission of force to said lever, resilient means capable of being stressed e armature, a second lever pivoted to the by said lever when the latter is moved by said drive shaft, and stationary but adjustable means disposed in the ath of said lever and serving as a fulcrum t erefor to enable the armature to be pried off its pole pieces by said lever when moved by said inelastic transmission of force, said means bein adjustable to a position wherein stressing of said means by movement of said lever is prevented or to a position wherein such stressing is permitted.

12. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, a lever connected to the armature for moving the same and pivotally supported at a point beyond one end of the armature, said lever extending beyond the other end of the armature and terminating with a pivotal support, a second lever mounted to turn on said pivotal support, means for applying a driving force to said second lever to turn the same on said support as a fulcrum, and means in the path of said second lever effective when engaged thereby to arrest the second lever and temporarily serve as a fulcrum therefor, thereby to enable the second lever to pry the armature off its pole pieces.

13. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, a pivotal support carried by the armature, a lever mounted in termediate its ends to turn on said support, driving means engageable with said lever on one side of said support for moving the same by an inelastic transmission of force, resilient means engageable with said lever on the opposite side of said support, and limiting means in the path of the last named side of said lever to engage the same after said resilient means has been stressed and to temporarily serve as a fulcrum to enable the armature to be pried oil said pole pieces by said inelastic transmission, said stressed resilient means effective after the armature has been pried off its pole pieces to move the lever and complete the flight of the armature away from its pole pieces, the part of said driving means engaged with said lever serving as a fulcrum therefor when the lever is moved by said resilient means. I

14. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, a pivotal support carried by the armature, a lever mounted intermediate its ends to turn on said support, driving means engageable with said lever on one side of said support for moving the same by an inelastic transmission of force, resilient means engageable with said lever on the opposite side of said support, and limiting means in the path of the last named side of said lever to engage the same after said resilient means has been stressed and term d after the armature has been'moved out of silient means effective after the armature has been pried off its pole pieces to move the lever and complete the flight of the armature away from its pole pieces, the part of said driving means engaged with said lever serving as a fulcrum therefor when the lever is moved by said resilient means, said limiting means being movable to a position such that stressing of said resilient means by said lever is prevented, whereby the flight of the armature away from its pole pieces may be effected entirely by said inelastic transmission of force.

15. In a magneto of the type wherein an armature is moved into and out of contact with magnetic pole pieces, a pivotal support carried by the armature, a lever mounted to turn on said support, driving means for effecting an inelastic transmission of force to said lever at one location, resilient means for effecting, an elastic transmission of force to said lever at another location, and a member serving as a fulcrum for the lever to enable the lattertobe movedb saidinelastic transmission of force to move t e armature out of contact with its ole pieces, said member being movable to ifl'erent positions, in one of which said resilient means is rendered ineffective to move said lever and in others of which the le. ver, when first moved by said driving means turns on said pivotal support as a fulcrum and effects a stressing of said resilient means before engagement with said member, whereby contact with its pole pieces said resilient means in relieving itself of stress moves said lever about the part of driving means engaged therewith as a fulcrum and thereby moves said armature.

16. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, mechanism for moving the armature away from its pole pieces, comprising, a pivotal support carried by the armature, a lever mounted at a point intermediate its ends to turn on said support and extending in a direction generally transverse with respect to the armature, a drive shaft, a cam operated thereby and transmitting a force to one end of said lever, whereby the latter turns on said support as a fulcrum,

resilient means engaging the other end of thelever and stressed by the described movement, a member in the path of said last named end of the lever and engageable thereby to limit the stressing of said resilient means, said member when first engaged by the lever serving as a fulcrum therefor to enable the armature to be pried off its pole pieces by the movement of the lever effected by said cam, the cam then servin as a fulcrum for the lever while the latter is moved by said previously stressed elastic means.

17 In a magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, mechanism for moving the armature awa from its pole pieces, comprising, a pivota support carried y the armature, a lever mounted at a point intermediate its ends to turn on said support. and extending in a direction generally transverse with respect to the armature, a drive shaft, a cam operated thereb and transmitting a force to one end of sai lever, whereby the latter turns on said support as a fulcrum resilient means engaging the other end 0 thelever and stressed by the described movement, a member in the path of said last named end of the lever and engageable thereby to limit the stressingof said resilient means, said member when first engaged by the lever serving as a fulcrum therefor'to enable the armature to be pried off its pole ieces by the movement of the lever effected y said cam, the cam then serving as a fulcrum for the lever while the latter is moved by said previously stressed elastic means, said member being movable to'a position such as to render said resilient means ineffective to move said lever.

18. In a magneto, having two sets of mag netic pole pieces and an armature for each set movable into and out of contact therewith, said armatures disposed in s aced parallel relation, :1 pair of levers one or eacharmature and connected thereto for moving the same,-each lever being pivotally supported at a point beyond one end of its armature and extending alongside its armature to and beyond the other end of the same, a drive shaft the axis of which lies ina plane between said levers, and means for operating said levers at properly timed intervals from said common drive shaft including means engageable with the last named ends of said levers.

19. In a magneto, having two sets of ma netic pole pieces and an armature for eac set movable into and out of contact therewith, said armatures disposed in spaced parallel relation a pair of levers one for each armature and connected thereto for moving -the same, each lever being pivotally supported to turn about a common axis at a point beyond one end of its armature and extending alongside its armature to and be yondthe other end of the same, a drive shaft the axis of which lies in a plane between said levers and common driving means for both said levers operating on the free ends thereof and located adjacent each other and beyond the last named ends of the armatures.

20. In a magneto, having vtwo sets of magnetic pole pieces and an armature for each set movable into and out of contact therewith,-said armatures disposed in spaced par-r allel relation, a pair of levers one for each armature and connected thereto for moving the same, each lever being pivotally supported at a point beyond one end of its armature and extending alongside its armature to and beyond the other end of the same, a

drive shaft the axis of which lies in a plane between said levers, a cross lev'er carried by the free end of each first named lever, the inner ends of both cross levers disposed adjacent to each other and said drive shaft,

and means on the latter for operating said armature and connected thereto for moving the same, each lever being pivotally supported at a point beyond one end of its armature and extending alongside its armature to and beyond the other end of the same, a drive shaft the axis of which lies in a plane between said levers, a cross lever carried by the free end of each first named lever, the inner ends of both cross levers'dis'posed adjacent to each other and said drive shaft, a fulcrum member for each cross lever disposed near the outer end thereof, and means on the drive shaft for operating said cross levers in properly timed relation.

22. In a magneto, having two sets of magnetic pole pieces and an armature for each set movable into and out of contact therewith, said armatures disposed in spaced par-. allel relation, a pair of levers one for each armature and connected thereto for moving the same, each lever being pivotally supported at a point beyond one end of its armature and extending alongside its armature to and beyond the other end of the same, a drive shaft the axis of which lies in a plane between said levers, a cross lever carried by the free end of each first named lever, the

inner ends of both cross levers disposed adjacent to each other and said drive shaft, a fulcrum member for each cross lever disposed near the outer end thereof, resilient means capable of acting on the outer end of each cross lever, and means on the drive shaft for operating said cross levers in properly timed relation, said fulcrum members being shiftable to render said resilient means effective or ineffective to operate said levers as desired.

23. In a magneto, having two sets of magnetic pole pieces and an armature for each set movable into and out of contact therewith, said armatures disposed in spaced parallel relation, a pair of levers one for each armature and connected thereto for moving the same, each lever being pivotally supported at a point beyond one end of its armature and extending alongside its armature to and beyond the other end of the same, a

drive shaft the axis of which lies in a plane between said levers, a cross lever carried by the free end of each first named lever, the inner ends of both cross levers disposed adjacent to each other and said drive shaft, a fulcrum member for each cross lever disposed near the outer end thereof, resilient means capable of acting on the outer end of each cross equally limiting the shifting movement of said fulcrum members.

24-t. Ina magneto, of the type wherein an armature is moved into and out of contact with magnetic pole pieces, mechanism for moving the armature out of contact with its pole pieces against the restraining force of magnetic attraction, said mechanism comprising, a lever connected at a point intermediate its ends to the armature and pivotally mounted at a point beyond one end and extending beyond the opposite end of the same to be operated by a driving force, whereby a long arm is available permitting a reduction in the driving force necessary to pry the armature off its pole pieces, a cross lever pivotally supported intermediate its ends on and extending crosswise of the first lever near the free end thereof, means for applying a driving force to one end of said cross lever, and means serving as a fulcrum for the latter during the application of said force, whereby the force applied to said cross lever is in creased when transmitted to the first named lever and the force/applied tocthe latter is still further increased when, transmitted to the armature, whereby the latter may be pried off its pole pieces with a relatively small driving force.

25. In a magneto, of the type wherein an armature is moved toward and away from magnetic pole pieces, a lever pivotally supported at one end and at a point intermediate lever pivoted to the first lever near the free "end thereof and extending substantially transverse thereto, a cam to operate said second lever, and means interposed between said cam and second lever to relieve the latter from the thrust imparted by said cam.

26. Ina magneto, of the type wherein an armature is moved toward and away from magnetic pole pieces, a lever pivotally supported at one end and at a point intermediate its ends serving to support the armature, a lever pivoted to the first lever near the free end thereof and extending substantially transverse thereto, a cam to operate said second lever, a cam follower interposed between said-cam and second lever with which the latter is slidingly engaged, an arm pivoted at one end and to the other end of which said follower is fixed, said arm extending in substantially the same direction as the second lever and serving to take the thrust imparted by said cam which thrust would otherwise tend to displace the second lever longitudinally and thereby exert a lateral thrust on the first named lever. Y

27. In a magneto, of the type in which an armature is moved toward and away from magnetic pole pieces, mechanism for moving said armature including a driving member and a plurality of multiplying levers interposed between said member and the armature for increasing a relatively small force applied by said driving member so that it is adequate for moving said armature.

28. In a magneto, of the type in which an armature is moved toward and away from magnetic pole pieces, mechanism for moving said armature including a driving member and a plurality of multiplying levers interposed between said member and the armature for increasing a relatively small force applied by said driving member so that it is adequate for moving said armature, and a single device efiective by adjustment to move the several parts of said mecahnism into close operating contact, whereby impacts between said parts are avoided in operation.

29. Armature actuating means for a magneto, comprising in combination with a reciprocable armature thereof, a lever extending generally crosswise with respect to the armature and having intermediate its ends a pivotal bearing movable with the armature, means for applying a driving force to said lever near one end, and a member for engagement with said lever near its other end to serve as a fulcrum therefor.

30. Armature actuating mechanism for a magneto, comprising in combination with the reclprocable armature thereof, a lever extending lengthwise ofthe armature and fulcrummed beyond one end thereof, said lever at an intermediate point in its length being connected to move the armature and extending beyond the opposite end thereof, a lever engaged with the free end of the first lever and disposed substantially transverse thereto, a fulcrum for said second lever, and means for applying a driving force to said second lever.

31. In a magneto, .having two magnetic circuits including two sets of magnetic pole pieces, armatures one for each set of pole pieces adapted for movement into and out of contact therewith, means for moving first one and then the other armature away from its pole pieces, elastic means tending to move the armatures toward their pole pieces, and means for preventing each armature from being moved into contact with its pole pieces under the action of said elastic means until the other armature has been moved out of contact with its pole pieces and commenced its flight away from the same.

32. In a magneto, having two magnetic of contact therewith, elastic means tending to move each armature toward its pole pieces, a drive shaft, driving means oper able by an inelastic transmission of .force from the drive shaft to move the armatures away from their respective pole pieces in succession and arranged so that both armatures cannot contact with their pole pieces at the same time, elastic driving means for optional use in conjunction with the first named driving means in moving the armatures away from their pole pieces and effective to start the armatures at later points in the revolution of the drive shaft than when the. first named driving means is used alone, whereby one armature tends to move back into contact with its pole pieces before the other armature has started away from its pole pieces, and means for arresting each armature in its flight toward its pole pieces until the other armature has been started in its flight away from its pole pieces. I

- 33. In a magneto, having two magnetic circuits including two sets of magnetic pole I pieces, armatures one for each set of pole pieces adapted for movement into and out of contact therewith, means for operating the armatures arranged to move first one and then the other armature away from its pole pieces, and means for arresting each armature in its movement toward its pole pieces and holding it space-d away from the same until the other armature has started its movement away from its pole pieces.

34. In a magneto, having two magnetic circuits including two sets of magnetic pole pieces, armatures one for each set of pole pieces adapted for movement into and out of contact therewith, means for operating the armatures arranged to move first one and then the other armature away from its pole pieces, and means for preventing each armature from bein drawn into contact with its pole pieces until the other armature has been started in its flight away from its pole pieces.

35. In a magneto, having two magnetic circuits including two sets of pole pieces, two independentl movable armatures, one for each set of o e pieces and each adapted to reciprocate etween a position wherein the reluctance if its magnetic circuit is relatively small to a position wherein such reluctance is relatively large, means for operating said armatures in succession, and means independent of said operating means for preventing each armature from moving back into the first named position until the other armature has started to move from its first named position towards its second named position.

36. In a magneto, having two sets of magnetic pole pieces and an armature for each a cross lever pivotally mounted on each lever beyond the last named end of its armature, and means on the drive shaft for actuating the cross levers in groper timed relation.

In testimony w ereof I have aflixed my signature.

- IRA E. HENDRICKSON.

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