US1498320A - Internal-combustion-engine starter - Google Patents

Description

June 17 1924.

Filed April 13 1923 2 Sheets-Sheet l yes TTORIVE Y 4 E i: I a:

INVENTOR Jamil 1159 June 17 1924. 1,498,320

7 F. A HAYES INTERNAL COMBUSTION ENGINE STARTER 7 Filed April 13, 1923 2 Sheets-Shut 2 INVENTOR FankA/Z? a ATTORNEY Patented June 1?, 1924.

UNiTED STATES v 1 1,498,320 PATENT orrica.

FRANK A. HAYES, F KEYIPGBI', NEW JEBSEY, ASSIGNOR T8 AERQMABZNE 6 MOTOR COMPANY, A CQBPQRATIUH 0F N'EW. 1 0E131!- DHIEBNAIEGOMBUSTIQN-ENGINE STARTER.

Application tiled April 13, 1923 Serial Ho. 331,758.

. To all whom it may concern. I

Be it known that I, Fmmr A. HAYES, a citizen of the United States, and a resident of Keyport, in the county of Monmouth and State of New Jersey, have invented certain new and useful Improvements in Internal-Combustion-Engine Starters, of which the following is a specification, reference being had to the accompanying drawings, forming part of this specification.

This invention relates in general to power driven starting devices for internal combustion engines, and the preferred form as shown and described herein is primarily adapted for use with aeronautical motors, and to be used in conjunction with a power drive, such as an electric motor, although not confined to such use exclusively.

The present embodiment constitutes an improvement on existing forms o;t ower driven engine starters principally vvit reference to an over-load. release-feature hereinafter described, although other new and novel features are disclosed which form important improvements over the prior art.

The starting mechanism for an aeronautical engine must provide the torque necessary for starting a cold and stiff engine and at the same time the construction should 30 be such as notto materially increase the weight of the power plant as 'a whole, to this end the mechanism "for such engines must be designed for a definite torque sufficient to crank the engine under the most adverse conditions likely to occur in general use, and particularly under conditions where the inertia of the motor armature is added to its electrical torque.

It is not practicable, however, to limit a power drive such as a high speed electric motor, to a definite maximum torque, particularly under conditions where the inertia of this motor armature is added to its electrical torque, and hence some releasing mechanism should be provided to meet heavy -over-loads.' To this end I have featured herein elements providing an over-load release.

The most usual cause of such over-loads consists of a backfire which may occur during starting of the engine, and which tends to reverse the same or actually reverses 1t, thereby putting a momentary torque on the starting mechanism greatly 1n excess of the normal starting torque required. Also the engine may be damaged, causing sonie of the moving parts to jam and making it impossible to start without repairs. In the present disclosure, eiiective means are provided against breakage of the starter drive mechanism following on such a contingency.

In the prior art over-load or backfire release means have been provided by the utilization of spirally splined members acting against a heavy spring to retract toothed clutch members on an over-load. With this type of release the driving clutch members are drawn out of mesh under maximum load conditions, the violent contact and slippage of the corners of the teeth against one another resulting in injury to these parts. This very severe action reduces the ire of the mechanism and also throws it out of adjustment by rounding the corners of the clutch teeth, thus tending to make the mechanism release under lighter loads. The principal feature of the present invention consists in the provision of means for relieving all driving load on the mechanismbefore the releasing or demeshing action actually takes place.

The particular form of starting mechanism isclosed herein comprises a gear train adapted to provide the large speed reduction necessary to permit the use of a light compact starting motor suitable for storage battery operation. This gear train contains a sliding pinion so designed as to permit the use of. very few teeth (five teeth being used in the present construction) for the purpose of getting a large reduction in as compact and light a structure as possible. Automatic meshing of this pinion is effected by a cam acting against a pin and demesh-' ing may be assisted by a secondary cam as more fully described hereinafter.

The present embodiment constitutes an improvement over the form shown and described in the co-pending applications of @hilton, filed May 19,1921, Ser. No. 471,002 and King et 211., 1,480,397 January 8,. i924 and consists primarily of an addition to the meshing cam -faces therein featured, the present cam means being so formed as to permit the drive pin to ride over the high portion of the cam and cause an instantaneous release, and a subsequent demeshing, of the pinion when the load on the mechanism exceeds a predetermined amount.

The primary object is to provide a starting mechanism which relieves the gear teeth of all driving load before demeshing under over-load takes place, thus preventing excessive wear and damage to the corners of the teeth during the demeshing operation.

Another object is to provide a starting mechanism in which remeshing is prevented except when the relative speed of the meshing members is low.

A further object is to provide a starting mechanism in which the driving efl'ort is cushioned under all conditions against a spring providing complete protection to the operating parts from shock or over-stress.

A still further object is to provide a starting mechanism in which the amount of mesh of the pinion teeth with the driven gear is approximately proportional to the driving effort required, thereby tending to give uniform tooth loading Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying drawings and a careful consideration of the following particular description and claims of one form of mechanism embodying my inven tion.

Inthe drawings v Figure 1 is a vertical longitudinal section taken approximatelyat the center, showing a preferred embodiment of my invention in the form of an attachment mounted in operative engagement with an engine of the type usually found in aeroplane motive power construction.

Figure 2 is a fragmentary horizontal section of Fig. 1 taken on the line 2 looking in the direction as indicated by the arrow showing the shiftable pinion and its directly asis formed of slightly lesser diameter than the sociated parts in an inoperative or demeshed position.

Figure 3 is a similar view to Fig. 2, showing the pinion and associated parts in operative driving engagement under full load.

Figure 4 is a fragmentary view of the pinion and adjacent parts as viewed from the same aspect of Figs. 2 and 3 showing the position of the parts in the act of releasing just prior to the demeshing of the pinion following a back fire in the engine.

Figure 5 1s a transverse section taken on the line 5 of Fig. 1v and looking in the direction as indicated by the arrow.

Figure 6 is a diagrammatic view showing a development of the meshing and the demeshing cams and graphically illustrating their relative positions prior to the starting of the electric motor.

Figure 7 is a diagrammatic view similar to that of Fig. 6 showing the relative positions of the cams following a backfire when the electric motor is still in operation.

Figure 8 is a fragmentary detail view on an enlarged scale of an under pinion tooth in section adjacent to an upper tooth of the neeasao large driven gear showing the chamfered corners of the teeth.

Figure 9 is a diagrammatic view similar to Fig. 6, on an enlarged scale and illustrates a modification in which the cams have a relatively fixed relation.

In the present instance 10 designates a portion of a conventional form of internal combustion engine, 11 thecrankshaft thereof. To the engine 10 there is secured by means of the screws 12 a housing 13. The housing is designed to afford a support for an electric starting motor 14 and is provided with a front wall portion 16 and a cover plate 17.

A. gear train providing a large speed reduction is housed between the wall 16 and the cover plate 17 and comprises a small motor pinion 18 in constant mesh with a relatively large first reduction gear 19. The gear 19 is secured to a hollow cylindrical hub portion 20 by the screws 21, said hub portion having a bearing in a cylindrical housing 22 integral with the wall 16.

A drive shaft 23, one end of which is operatively connected to the crankshaft 11 is suplported in a bearing 24 and has a gear 25 secured thereto, said gear being provided with teeth 26 which are chamfered, the purpose of .wfhich will be more fully described hereina ter.

An axially shiftable pinion 28 having teeth 29 is disposed partlywithin the cylindrical hub portion 20 ahd is slidably and rotatably supported ina bearing 31 at one end. and in a bearing 32 formed by a constricted portion'of the housing 22 at the other end.

The end of the pinion which is supported in thebearing 32 is fitted with a cylindrically formed friction member 33 the bore of which contact. A longitudinal slot 34 is provided' in the friction member said slot being engaged by a key-piece 35 secured in the hearing 32. The key-piece prevents rotation of the friction member, but permits axial movement thereof, thereby allowing the pinion 28 to have a free axial movement, but causing a certain amount of frictional restraint against rotation thereof. See co-pending application Kinget al. hereintofore mentioned.

A cylindrically formed cam member 37 more specifically referred to as the meshing cam is disposed within the hub 20 and secured thereto so as to rotate therewith by the splines 38. The cam face has a helical formation and comprises two high portions 39 andtwo low portions 40, the high portions and the low portions being diametrically opposite one another respectively.

Another cam member 42 similar in construction to the cam 37 and more specifically referred to as the demeshing cam may be mounted for free partial rotation within the hub 20. This cam is provided with two high portions 44 and'two low portions 45, said cam being disposed adjacent the cam 37 in a manner so as to provide a path between the two cams for a pinion drive pin 46 extending diametrically through the pinion 28. A torsion spring 47 one end of which is secured to said cam and the other end of which is secured to a portion of the gear 19, tends to keep the high portions 44 ofthe cam normally against the high portions 39 of the cam 37 as shown in Figs. 2, 3 and 6. A snap ring 48 placed in a groove in the hub portion secures the cam 42 against end movement.

A rugged compression spring 49 surrounds the pinion 28 and is adapted to act asa cushion therefor as will be more fully described hereinafter.

In operation and considering the elements first in their inoperative position as shown in Figs. 1, 2, 5, and 6, the rotation of the crankshaft 11 and the starting of the engine is accomplished in the following man- With reference to Figs. 1, 3, and 6, it will be understood that the gear 19 is rotated by the-pinion 18 when the motor 14 is started. The meshing cam 37 being spli-ned to the hub portion 20 will be rotated therewith in the direction indicated by the arrows in Figs. 3 and 6 causing the angular face 51 of the cam 37 toengage the drive pin 46. 'The pinion 28 being frictionally restrained against rotation will be axially moved into mesh with the gear 25 by the action of the cam against the drive pin 46 until the shoulder 52 of the pinion 28 and its adjacent collar 53 are brought to bear against the compression spring 49, the pinion 28 will overcome the friction of the member 33 and will be caused tc rotate by the continued action of the cam against the drive pin 46, as shown in position 46*, Fig. 6. The demeshing cam 42 will under normal driving conditions bear against the cam 37 and be maintained in this position by the action of the spring 47. (Fig. 6.)

In the above described manner the gear 25 and the crankshaft '11 will be caused to rotate and the engine started, the driving elements occupying approximately the relative positions as shown in Figs. 3 and 6.

\Vhen an overload occurs, that is, a load in excess of that for which the spring 49 is designed, the reaction of the inclined surface 51, Fig. 6, of the cam'37 against the pin 46 will force the pin upon the high portion 39 of the cam 37 and thus move the pinion 28 axially into further mesh with the gear 25 against the tension of the spring 49. It is obvious that while this axial movement takes place-the rotational driving effort of the cam 37 on the pin 46 with the exception of a slight frictional effect is being overcome. The gear 25 is thus free to stop or, under a backfire to reverse violently, this sudden arresting or reversing of the gear and the meshed pinion will cause the pin to ride off of the high.portion 39 and thus permit the spring 49 to force the pinion out of mesh and bring the pin 46 against the low portion 40 of the cam while all driving efl'ortis still relieved. During this movement of the pinion the pin moves circumferentially in the channel between the cams 37 and 42 and strikes the projection44 of the cam 42 thus carrying said cam with it against the tension of the spring 47 to the relative positions shown in Fig. 7. The pin reaches the bottom or left hand portion of the channel so rapidly "that the spring 47 does not have time to overcome the inertia of the cam 42, and the pin 46 is prevented from remeshing the pinion by the projection- 44 of the cam 42. This action of the cam 42 can be regulated by changing the relation between the inertia of the cam 42 and the strength of the spring 47 the action of the spring 47 is further delayed by the frictional eii'ect of the pin 46 against the cam face 44. Positive means for holding the cam in the position shown in Fig. 7 while the cams are still being rotated may be used, such as an automatic centrifugally actuated latch or a dashpot or other means manually released as will be readily understood by those skilled in the art. In the present instance one such form has been diagrammatically shown in Fig. 7 in which an annular grooved member 61 is mounted for rotation with the gear 19, said member 61 being provided with a latch 62 adapted to engage a projection 60 on the cam 42 when said-cam is moved into the position shown, a bifurcated member 63 operates in the groove of the member 61 and is actuated by a spring 64 to move the member 61 with its latch 62 into an engaging position. Means for manually releasing the device is provided by 65.

Following on a normal start, when the rotational speed of the gear 25 begins to exceed that of its driving pinion due to the engine speeding up under its own power, the pin 46 will recede from its position as shown by 46*, Fig. 6. and resume its initial position under the influence of the spring 49 and the cam 42, the action of friction sleeve 33 preventing the pin from moving ahead of cam 37 and trying to remesh against face 55,

(Fig. 6). u

With reference to F 1g. 8 'in which there is detailed an under tooth 29'of the pinion 28 adjacent an upper tooth 26 of the gear 25 showing the chamfered corners 58, 59. It will be noted, that the teeth of both the pinion and gear are chamfered at a relatively steep angle at 58 on the non-driving .side so as to facilitate a meshing. It will the reversed rotation being as indicated by the arrows in Fig. 8.

When the faces 59 of the pinion 28 and the gear 25 contact with any appreciable dif-' erence in speed between the two members, the pinion is repelled away from the gear by the cammin'g-action of these faces and before the same tooth faces can be again brought into contact, the relative rotational movement of the two members has carried another set of teeth into contact and the repelling action is repeated.

It is to be noted that should a remeshing actually occur, no damage will result as the overload release feature previously described will again be brought into action as the meshing and demeshing of the teeth occurs at practically no load this action may take place at any speed Within the range of the mechanism Without detrimental results.

It is to be understood that while the mechanism shown and described in the present instance discloses the toothed meshing parts as consisting of a spur gear and pinion, other forms-of toothed or splined members may be substituted therefor without departing from the scope or spirit of the invention. With reference to Fig. 9 there is shown an alternative formation of the cams 37 and 42 in which the two cams bear a fixed relation to one another thus providing a path or channelbetween the two for the pin 46 to travel in, the cam 42 being secured in any suitable manner to the hub 20 and the spring 47 eliminated. The meshing and demeshing action in this instance will be substantially the same with the exception that remesl1ing of the. pinion following a backfire with regards to this modified form will be effectively prevented by the chamfered gear teeth, or an automatic latch or stop may be provided adjacent to the bearin 31 which will effectively prevent a remes ing unless said latch is manually moved to a released position. With such a latclrto prevent axial movement, the pinion will be idly rotated against the friction of' the member 33.

While I have shown and described in the present instance a cam 42 it will be understood that this cam can be dispensed with if so desired while still maintaining the overload release feature, the cam 37 functioning as such a means and co-acting with the spring 49 to cause a meshing or demeshing of the pinion, the principal feature of this invention being as stated, the provision of means for relieving all driving load on the mechanism before the releasing ordemeshing actionactually takes place," subsequent remeshing of'the pinion under these conditions will be effectively prevented by the chamfered teeth or other means known to those skilledill the art.

While I- have shownand described and have pointed out in the annexed claims certain novel features of my invention, it will be understood that various omissions, substitutions and changes in form and details of the device illustrated-and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

Having "thus described my invention, I claim 1. In the art of connecting a starter to an engine to be started, a driving member, a mesh member, a driven member, a spring, a cam means connecting the driving member with the mesh member and cooperating with saidspring so as to produce a release and subsequent retraction of the mesh member when the driving load exceeds a predetermined maximum.

2. A device of the class described, comprising a driven means attached to the en gine, a driving means, a cam, a mesh means adapted to driveably connect the driving with the driven means and having meshing movement from said cam, a calibrated spring actin in restraint of said meshing movement, t e whole constituted so as to effect a release of the meshmeans from the driving means and a subsequent retraction of the mesh means when the compression of said spring reaches a predetermined amount.

3. In apparatus of the class described, a driving member, a driven means, a mesh pinion, a cam means, the pinion connected to the driving member by said cam means, the cam means cooperating with a spring so as to effect an automatic meshing of the pinion with the driven means and to maintain the pinion in meshed position until the driving load shall exceed the resistance of said spring, the cam means being so constituted as to then permit the driving means to overmeans, a cam connection between the meshing and the driving means and having an element tending to produce mesh of the meshing means under normal driving load, a second element of said cam connection tending to produce demesh under over-load, and a spring tending to maintain the meshing means in contact with the first said element until an overload occurs.

6. In a starting apparatus, a member to be started, a mesh pinion adapted to engage said member, a cam means, means on the mesh pinion coacting with said cam means, a mesh producing profile and a demesh producing profile on said cam means, and a spring tending to restrict the coacting means to themesh producing profile until an overload occurs.

7. In a starter mechanism, a meshing means cooperating with a cam means having profiles adapted respectively tomesh and to demesh said meshing means, in combination with a spring adapted to restrain the action to the meshing profile except under excessive driving effort.

8. In the art of protecting a starter mechanism from damage due to excessive load, the combination of a pinion, cam means coacting therewith and having positive and negative profiles adapted to produce respectively meshing and demeshing of said pinion, and a spring adapted to cooperate with said pinion to limit said coaction to the positive'or meshing profile of the cam except under excessive loads.

9. In a starter mechanism, a driving means, a meshing pinion, a cam means adapted to produce automatic mesh of the pinion upon rotation of the driving means,

a spring adapted to limit the extent of said meshing of the pinion under normal loads, and further cam means adapted to produce a demeshing action following on excessive compression of said spring by abnormal loads. I

10. In a starter mechanism, a driving means, a driven means, a meshing means, cam means connecting the meshing means to the driving means, asprin the cam'means having a first element tending to move the meshing means axially intomeshed position with the driven means and in opposition. to the spring, and a second element of said cam means adapted to permit" of an over-run between the driving means and the meshing means upon a certain degree of spring compression.

11. In a starter mechanism, a meshing pinion, a spring means, a,cam means adapted to drive the pinion and having a profile adapted to produce automatic mesh thereof upon initial rotation of the cam means and co-acting with the spring means to limit said meshing movement under a normal drive, said cam profile being further so constituted as to ceaseto drive the meshing pinion when a certain degree of spring compression has been reached and to thereupon cause the relative rotation between the parts to etiect a retraction of the pinion from mesh.

12. In a starter gear, a mesh member, a

spring, a cam adapted to automatically mesh the mesh member with a member to be driven and cooperating with the spring to drive said mesh member,.the cam means being so formed as to constitute a driving means for the mesh member only under normal loads. a

13. Inapparatus of the class described, a gear train, a shittable pinion forming a separable driving connection and adapted for mesh or demesh with a gear iii said train, a cam means, a spring means, said cam and spring means coacting with the pinion to maintain said driving connection, said cam means so formed as to relieve the driving efiort of the pinion while in a meshed position and to permit a subsequent retraction thereof when a driving load is encountered in excess of the resisting power of said spring.

14. In a device of the class described, the combination of a gear driven from a power means, a second gear connected to an engine to be started, a shiftable and separable driving connection between said gears, a cam means adapted to advance the driving connection into meshed position, a yielding means opposing such advance of the driving connection, said cam means having profiles adapted to eifect a retraction of said connection into a demeshed position when the driving load overcomes said yielding HHZUIS.

i5. In a device of the class described,.the combination of a motor drive, a gear driven from the motor, a second gear connected to an engine, a shiftable member forming a driving connection between said gears and adapted to mesh with one of the gears, a spring, a means comprising a cam having profiles adapted to advance and to maintain the shiftable member in a meshed position against the action of the spring under driving torque not in excess of a predetermined amount for which said spring is set said means also having profiles adapted to cause a retraction of said shittable member into a demeshed position when, the driving torque is in excess of a predetermined amount.

16. In a device of the class described, the combination of a motor drive, a gear driven from the motor, a second gear connected to an engine, a shiftable driving connection between said gears and adapted to mesh with. one of the gears, a means comprising a cam adapted to advance and to maintain the driving connection in a meshed position under normal driving torque not in excess of a predetermined amount said means also adapted to cause a retraction of said connection into a demeshed position when the driving torque is in excess of a predetermined amount, and other means adapted to prevent a subsequent remeshing of the driving conby the am to move said pinion into operative engagement wlth a gear in said gear drive and out of engagement with said gear.

under overload conditions, and a calibrated spring adapted to control said movement of the pinion. I

18. in an engine starting mechanism, 111 combination, an engine to be started, a motor, means driven from said motor adapted to drive said engine, said means comprising a cam, a shiftable driving connection actuated by said cam, a spring member adapted to control the amount of driving force applied to start said engine and to co-act with said cam to cause said driving connection to be shifted to an inoperative position when the mechanism is subjected to an overload.

19. In an engine starter, the combination of a casing, a starter mechanism housed within the casing and including a driving shai't adapted to be connected to a revolving element of the engine, a motor carried by the casing, a reduction gear train for driving the shaft from the motor, a cam, a driving element controlled by the torque of the motor and actuated by the cam for moving said element into an operative position to form a drivin connection with a gear in said train, means including a spring coacting with said cam, said means controlled by excessive torque on the shaft for moving said driving element into an inoperative position.

20. In a device of the class described, the

' combination of a gear train including a gear having a hollow hub, a cylindrical cam member secured in the hub and having a helically formed face, a second cylindrical cam formed substantially like the first cam and having relative motion therewith and disposed within said hub in a manner so as to provide a channel between the faces of the first and the second said cams, a driving con nection comprising a pinion, said connection being slidablyand rotatably mounted in a bearing and extending axially through said hub and said cams, a pin extending dia-' metrically through the driving connection, the faces of said cams adapted to shift the pinion into or out of effective relation with a gear in said train by means of said pin, and other means adapted to control the action of said cams'on the pin;

21. In a device of the class described, a gear train, a gear in said train and havinga hollow hub, a cylindrical cam secured in the hub and having a helically formed face, a second cylindrical cam formed substantially like the first cam and disposed within incense said hub in a manner so as to provide a channel between the first and the second said cam faces, a driving connection comprising a pinion, said connection being slidably and rotatably mounted in a bearing and extending axially through said hub and said cams, a pin extending diametrically through the driving connection, the ends of said pm adapted to travel in said'channel and actuated by said cams to shift the pinion into or out of edective relation with a gear in said train, and means adapted to control the action of said cams on the pin. 22. In a device for starting engines and the like, the combination of a driving and a driven member, the driven member connected to an engine to start the same, means associated with the driving and the driven members forming a shiftable driving connection therebetween, means comprisinga plurality of cams to shift said connection, one of said cams adapted to shift the driving connection into edective relation with the driven means and to drive the same, means to retract the driving connection when the engine tends-t0 accelerate under, its own power, and means comprising one of said cams to prevent a subsequent re-engagement of the driving connection while the engine continues to function.

23. in a starting mechanism, the-combina- I tion of a motor drive, a first gear driven by the motor, a second gear connected to an engine to be started, the first gear provided with a hollow hub, a shiftable driving connection comprising a small pinion disposed within the hub and adapted to mesh with the -second gear, an overload release mechanism associated with the drivin connection and also disposed within the hu and comprising a severable cam connection axially arranged with the pinion to actuate the same, and a cushioning spring for the pinion.

24. in a device of the classdescribed, the combination of a motor drive, a gear driven therefrom, an engine to be started, a gear thereon, a shiftable driving connection comprising a pinion adapted to mesh with the second said gear, a plurality of helically formed cams, a pin in the driving connection, the ends of the pin disposed between said cams and adapted to be engaged thereby, a calibrated spring governing the action I therefrom, an engine to be started, a gear thereon, a shiftable driving connection com prisinga pinion and adapted to mesh with the second said gear, a plurality of helically formed cams, a pin in the driving connection, the ends of the pin disposed between said cams and adapted to be engaged there-- of the pinion teeth to facilitate a meshing of the pinion with the second gear when said gear is atrest.

26. In apparatus of the class described, the combination of a motor drive, a gear driven therefrom, an engine to be started,

a gear thereon, a shiftable driving connection comprising a pinion associated with the first gear, a pin in said connection, a cushioning spring, a pair of helically formed cams, means comprising one of said cams adapted to engage the pin to move the pinion into mesh with the second said gear and against the cushioning spring, said cam coacting with said spring to cause a subsequent rotation of the pinion under normal load conditions,'said cam also adapted to coact with said springto retract the pinion from a meshed position under overload conditions, the other of said cams adapted to prevent a remeshing of the pinion while overload conditions continue to exist.

27. In apparatus-of the class described, a

first gear constituting the driving means, a second gear constituting the driven means, a shiftable element associated therewith forming a separable driving connection and adapted to mesh with the second said gear,

' means to operate the driving connection said means comprising a first member havin a plurality of cam, faces, a second mem er having a plurality of cam faces and disposed relative to the first member so asto pro- 28. In a device of the class, described, the

combination of a motor drive, a gear driven therefrom, an engine to be started, a gear thereon, the first said gear having a hub rotating, in a bearin a shiftable' drivin connection associate with the hub an adapted to mesh with the second said gear, a means to shift the driving connection and comprising a helically formed cam secured to said hub, a pin in the driving connection, the ends of the pin disposed adjacent to said cam and adapted to be engaged thereby, a friction device engaging the driving connection, a spring calibrated to resist a predetermined normal driving torquc'and responsive to an overload torque to effect a demeshing of the driving connection.

29. In a device for starting engines and the like, a driving means, a driven means, a cam, a member adapted to form a driving connection between the driving and the driven means, said driving connection normally out of engagement with the driven means andlongitudinally shiftable into engagement and rotationally drivable by said cam when the driving means is functioning, and means coacting with said cam to release said driving connection and to subsequently shift the same out of engagement when the engine tends to reverse.

30. In a device for starting engines and the like, a driving means, a driven means, a member adapted to form a driving connection therebetween, a shifting means comprising a cam, said driving connection normally out of enga ement with'the driven means and longitu inall shiftable into engagement and rotationa ly drivable by the shifting means when the driving means is functioning, means coacting with said cam to shift said driving connection out of engagement when the engine has started and means comprisin a second cam having relative motion wit the first said cam to prevent re-engagement of said connection with the driven means while the engine is operating.

31. In a device for startingengines and the like the combination of an engine to be started, a gear train, a drive therefor, a member forming a. severable driving connection in said gear train, a means comprising a cam adapted to move said member ax-. ial y into mesh with a gear in said train when the torque of the drive is redominant, further -means coacting witi said cam adapted to move said member out of engagement when the torque of the engine becomes predominant, and ameans adapted to prevent a remeshing of said member.

drive upon a certain degree of movement of the mesh member against the action of the opposing spring.

33. In apparatus of the class described, a driving means, a mesh member, an opposing spring for the. mesh member, a cam means,

a first element on said camineans adapted to produce automatic mesh of the mesh member and to normaiiy drive the same, a

second element on said cam means adapted to efiect a discontinuance of said drive upon a certain degree of movement of the mesh member against the opposing spring, and a third element on the cam means adapted to permit demesh of said mesh niemherai'ter the continuance of the drive has been effected 34.. In apparatus of the class described, a meshing means, a cam means adapted to actuate the meshing means and to normally drive the same, said cam means being so constituted that a discontinuance of the said driving action shall occur when the meshing movement has reached a predetermined point, and a caiibrated spring acting in restraint of said Ineshing'movement,

35, in a starter mechanism, a driving means, a. meshing pinion, cam means adapted to PZOdUCG automatic mesh of the pinion upon rotation of the driving hie-ans, a spring adapted to iiinit the extent of said meshing of the pinion under notnml loads, and further cam means adapted to co-act with the first said can: means to produce a demeshing action following on excessive compression of said spring by ahnormai loads, said last mentioned cam means so constituted as to prevent a subsequent reineshing white the driving means is iunetionin messes 36. In a starter mechanism, a driving means, a driven means, a meshing pinion, a cam means adapted to produce automatic mesh of the pinion upon rotationvof the driving means, a spring adapted to limit the extent of said meshing of the pinion under normal loads, said cam means aiso adapted to permit a demeshing when the driven means overruns the driving means, further cam means so constituted as to prevent a remeshing under the last mentioned conditions;

37. in a starter mechanism, a driving means, a. driven means, a meshing pinion, a cam means adapted to produce automatic mesh of the pinion upon rotation of the driving means, a spring adapted to limit the extent of said meshing of the pinion under normal loads and further cam means having relative motion with the first said cam means and adapted to co-act therewith to. Produce a

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