US2245437A - Engine starter - Google Patents

Description

June 10, 1941. J DYER 2,245,437

ENGINE STARTER Filed Jan. 9, 1936 3 Sheets-Shet 1 ATTORNEM June 10, 1941. .L DYER 2,245,437

ENGINE STARTER Fil ed Jan. 9, 1936 3 Sheets-Sheet 2 JunelQ, 1 941. J. B. 'DYEW 2 2 4,431

ENGINE STARTER Filed Jan. 9, 1936 3 Sheets-Sheet 3 INVE TOR M ATTORNE?/ m/L/i Patented June 10, 1941 2,245,437 ENGINE STARTER John B. Dyer, Pendleton, Ind., assignor to General Motors Corporation, Detroit, Mich, a cor poration of Delaware Application January 9, 1936, Serial No. 58,278'

19 Claims.

This invention relates to improvements in engine starters and more particularly in the type of apparatus disclosed in my copending application Serial No. 36,866, filed. August 19, 193-5.

The engine starter of my copending application No. 36,866 comprises a pair of driving discs located on Opposite sides of a driven disc connected with the engine to be started. These driving discs are moved by means independent of the starting motor axiallly along a shaft which supports them into engagement with the driven disc. The connections between these driving discs and the shaft are such that when the starting motor operates to turn the shaft, the driving discs will he pressed against the driven discs with pressure suiiicient to insure a good driving connection for engine starting purposes and, when the engine becomes self-operative, this driving pressure will be relieved so that the engine cannot drive the starting motor; More specifically the engine starter of my copending application comprises a tubular shaft mounted to slide upon the starting motor shaft and longitudinally splined thereto. This tubular shaft carries one of the driving discs. The other driving disc is provided by a sleeve mounted to slide longitudinally upon the tubular shaft. One end of this sleeve is provided with camming members cooperating with camming rollers mounted upon and driven by the tubular shaft. These cams and rollers are so constructed and arranged that relative rotary movement between the sleeve and tubular shaft produces relative longitudinal movement. In order to cause the driving discs to be moved into engagement with the driven disc prior to the operation of the starting motor, the starter of my copending application provides means under the control of the operator to cause the tubular shaft to move longitudinally so as to move the driving disc carried thereby into engagement with the driven disc. After this occurs, the sleeve is caused to rotate by means independent of the motor whereby, due to the coaction between thecams of the sleeve and rollers of the shaft, the sleeve is caused to move longitudinally to move the other driving disc against the driven disc.

The present invention aims to improve upon the engine starter of my copending application by simplification of construction which results in reducing the cost of manufacture, while at the same time maintaining eficiencmdurability and quietness of operation. In carrying out this aim of the present invention my improved starter comprises chiefly a tubular shaft longitudinally splined to :the driven shaft and providing one of the driving discs, a sleeve providing the other driving disc mounted upon the tubular shaft and connected therewith by camming members which are provided externally of the tubular shaft and internally of the sleeve. These cammingmembers gral with the shaft 38.

are preferably mating helical ball bearing races which cooperate'to receive a plurality of ball'bearings which in effect act as screw-threads relative to the inner tubular shaft and outertubular sleeve. The plurality of ball bearings provide an efiicient anti-friction connection between the sleeve and the shaft while at the same time providing the necessary strength for an effective camming connection between these parts.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to' the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a side view partly in section showing a preferred embodiment of the invention in its normal condition. V

Fig. 2 is a Wiring diagram thereof.

Fig. 3 is a fragmentary longitudinal sectional View of a starting apparatus.

Figs. 4, 5, 6 and 7'are sectional views taken respectively on the lines t4, 55, 6-6 and 1-1 of Fig. 3.

Figs. 8, 9 and lOare diagrammatic views similar to Fig. 3 but showing themechanism in different positions of operation.

The motor 21 for starting the internal combustion engine is preferably an electric motor comprising field frame 2i associated with an end frame 22 and a housing 23 which carry bearings 24 and 25, respectively, for the motor armature shaft 26 which carries an armature ill.

Referring now particularly to Figs. 3 to 7 the shaft 26 carries a tubular shaft 3i) which is splined at St to the shaft 2t so that the tubular shaft 39 is at all times drivingly connected with the shaft 26 but may slide thereon to a limited extent. The tubular shaft 36 is urged against the end of the bearing 25 by spring 32 which surrounds the armature shaft 28 and which is located between the armature 2'5 and the left hand end of the tubular shaft 30.

The shaft 38 carries driving disc 33 and driving disc 34 adapted to move into engagement with and to drive a driven disc 35 connected with the engine to be started. Disc 33 is preferably inte- The driving disc 3d is connected with shaft 36 through a screw thread connection which is provided by a plurality of balls 38 occupying mating helical grooves 39 and 45) provided respectively by'the shaft 38 and the tubular sleeve-like extension 35a of driving disc 34. The screw thread connection between the driving disc 34 and the shaft 36 is such that, after the discs 33 and Zifihave been moved into engagement with the driven disc 35 by means to be described, rotation of the motor shaft 39 in a clockwise direction as viewed from the right end of Fig. 3 will cause the driving discs to be wedged against the driven disc with a pressure suiiicient for engine starting purposes, and so that, after the engine becomes self operative and the driven disc 35 attempts to rotate the driving discs 33 and 34 faster than they can be rotated by the starting motor, the driving pressure between the driving discs and the driven disc will be relieved so that the engine cannot drive the starting motor at excessive speed.

There are certain important advantages which result from using as the camming connection between the shaft 3%] and the driving disc sleeve 34a a screw thread provided by ball bearings disposed in a helical race provided by mating helical grooves of the shaft 30 and sleeve 34a. These ball bearings provide an excellent anti-friction support for the disc 34 upon the shaft 30 so that relative rotary and longitudinal movement between the disc 34 and shaft 39 may take place freely. This is important in connection with the operation of the means, to be described, for causing the driving discs to be engaged with the driven disc prior to operation of the starting motor. The free connection between the shaft 39 and the disc 34 is important also in connection with the disengagement of the driving disc with the driven disc when the engine becomes self-operating. Great freedom of movement between the driving disc 33 and 34 is necessary in order that the driving discs will clear the driven disc very promptly upon the over running of the driven disc with respect to the driving discs when the engine fires. The use of a plurality of ball bearings in a helical race is important since the wedging action which takes place between the driving discs while the motor is cranking the engine will be distributed over a relatively large number of parts so that the wear and possibility of breakage is minimized. It should also be noted that, by locating the camming connection between the driving discs externally of one and internally of the other, the length of the tubular extensions from the two driving discs has been made less as compared with the construction shown in my copending application, wherein the wedging cams are provided at the end of the tubular extension of one of the driving discs.

The engine starter includes a means independent of the starting motor for causing the driving discs 33 and 34 to be moved into engagement with the driven disc 35 before the starting motor operates to cause the driving discs to be wedged against the driven disc with pressure sufficient to transmit torque sufficient for engine starting purposes. This means for causing a-preliminary engagement of the driving discs with the driven disc will now be described.

The disc 3 has its tubular extension 34a provided exteriorly with a plurality of helical splines ti adapted to be engaged by the internally spllned flange d2 of a sleeve d3 which is supported by a disc 44 riveted to the left hand end of shaft 35. Disc l has tongues 3? received by a longitudinal groove d8 of sleeve 33. A spring 65 is located between the disc 4:3 and the flange 42 and tends to maintain the relative location of the sleeve t3 and disc 3% as shown in Fig. 3, that is, with the tongues ll bearing against the left hand ends of grooves 418. The sleeve 33 is longitudinally splined to the tubular shaft Due to the great mass of parts connected with the shaft 3i? including the armature shaft 26 and the armature 2 the shaft 38 tends to remain stationary as the sleeve 13 is moved longitudinally. Hence, the sleeve 33 moves: longitudinally without rotating substantially. The pitch of the splines 4| formed on the sleevelike hub 34a of disc 34 is such that, as the sleeve 43 is moved toward the left from its position shown in Fig. 3 the disc 34 will rotate relative to the shaft 33 in a direction such as to cause the disc 34 to move into engagement with the disc 35.

In order that the sleeve 43 may be moved toward the left from its position shown in Fig. 3 it is providedwith an external flange 49 for receiving the ends 56 of a bifurcated lever if? having at its upper end an elongated notch H which receives a pin '12 carried by bifurcated bracket 13 integral with an L-shaped bracket 14 attached to an electromagnet frame mounted upon the motor frame 2i. A spring 16 surrounds a stud T! attached to the bracket 13 and urges the upper end of the lever Ill against the pin 12.

The lever Ill is actuated electromagnetically by means which will now be described with reference to Fig. 2. As shown diagrammatically in Fig. 2, magnet frame l5 encloses electromagnet windings 8D and BI surrounding a movable solenoid armature 82 guided by the magnet frame 15 for sliding movement toward a stationary core 83 which is located in the magnetic circuit of the electromagnet. The armature 82 is connected by a link 8d with the lever lll. Armature 82 is associated with a rod 35 upon which is mounted a non-conducting collar 88 yieldingly urged by spring 87 against a shoulder 88, the spring 81 being confined between the collar 86 and a washer as held from moving toward the right by a pin 93. A spring 3| located between a stationary part 92 and the rod normally maintains the rod 35 and the armature 32 in the normal position as shown in Fig. 2.

The collar 83 carries a movable switch contact 95 adapted to engage with contacts 53 and 3 of the starting motor switch. Contact 96 is connected by wire 93 with a switch terminal 99. Contact 91 is connected with the starting motor 23 which is grounded at I63. Terminal 99 is connected with storage battery NH grounded at 32. Terminal 93 may be connected simultaneously with terminals I63 and 194 by a movable contact I95. Terminal IE4 is connected with contact tad of an antomatic switch having also a terminal 10! connected with windings 8G and 8|, 8i being connected with contact 91 and 39 being grounded at lfiB. This automatic switch designated in its entirety by numeral H9, comprises a suction chamber ill connected by pipe H2 with the intake manifold of an internal combustion engine. One wall of the chamber H! is provided by a diaphragm H3 which is attached to switch contact H4, said contact being normally in engagement with contacts I86 and lfil, said engagement being effected through the action of a spring H5 located so as to press the diaphragm H3 downwardly as viewed in Fig. 2.

As stated before, this starter drive includes the feature of causing the driving discs 33 and 36 to be moved into engagement with the driven disc 35 before operating the starting motor 28. This is accomplished by means independent of the motor, namely, the electromagnet means shown diagrammatically in Fig. 2. The manner in which the driving discs are caused to engage the driven discs will now be described particularly with respect to Figs. 8, 9 and 10.

To start the engine the operator turns the switch contact I05 so as to cause it to engage the contact I03 and the contact I04. The ignition is then turned on, the ignition circuit being connected with the terminal 103 which is then connected'with the battery NH. The terminal H34 being then also connected with battery ill I, current will flow from the battery Illl through the windings 8E3 ande i, the former being directly grounded at H18 and the latter being indirectly grounded through the motor 2E). The electromagnet windings 80 and BI being energized, the armature 82 will move toward the left thereby causing the lever 10 to move to swing toward the left in a clock-wise direction around its pivot 72. During the movement of the lever 10 the contact 95'will bemoving toward contacts 96 and 91; but before engagement of these contacts actually occurs, the driving discs 33 and 34 will be'brought into engagement with the driven disc 35 in a manner which will be apparent from a consideration of Figs. 8, 9 and 10.

As lever 10 moves toward theleft the entire drive assembly will be moved bodily toward the left from the position shown in Fig. 8 to that shown in Fig. 9 thereby causing the driving disc 33 to engage the driven disc 35. This movement of the drive assembly is resisted by the spring 32 which normally holds the shaft 39 against the bearing 25.

Further movement of the lever l toward the left causes the sleeve 43 to move to the left relative to the driving disc sleeve 3% thereby causing the driving disc 34 to be rotated in such direction relative to the shaft 30 that the disc 34 will be moved from its position shown in Fig. 9 to that shown in Fig. 10 wherein said disc 34 engages the.

driving disc 35. The driving discs have now completed their preliminary movements into engagement with the driven discs. Hence the starter drive has been rare-conditioned for operation by the electric motor. After the driving discs have completed their preliminary movement the lower end of the lever 10 cannot move any further toward the left.

Continued motion of thesolenoid armature 82 toward the left to close contacts 95, 96 and 9'! may take place by reason of the fact that there is lost motion between the upper end of the lever 10 and the pivot bearing 12. Just before these contacts are closed, the spring it is held by the solenoid armature 82 under compression, so that yielding pressure is applied between end 50 of lever l0 and the sleeve flange 44. Therefore; it is only after the driving discs have been brought into engagement with the driven discs under yielding pressure that the motor switch contact 95 is caused to engage the stationary contacts 96 and 91. When this occurs the motor operates to turn the shaft 26. The winding 8| is then short circuited and winding 30 only is effective to hold the motor switch closed. Winding 8:] comprises preferably a large number of turns of fine wire and winding 8! fewer turns of coarser wire. Both windings are required to effect movement of the armature 82 initially toward the core 63 but winding 80 only is required to maintain the armature 82. in its attracted position. The starting motor then will operate to cause the shaft 26 to rotate in a clock-wise direction as viewed looking in the direction of arrow 60 of Fig. 8. At the instant the motor starts to turn the shaft 26, the driving discs 33 and 34 being then in engagement with the driven disc 35, the first action isto increase the pressure between the driving discs and the driven discs due to the cooperation of the screw thread connection between the driving discs.

Thus in responseto the operation of the electrio motor in turning the shaft 26 the driving discs '33 and-'34 are caused to press against the driven disc 35 with pressure sufficient to insure a driving engagement between the electric motor and the engine for engine starting purposes. Hence the electric motoris drivingly connected with theengine and will start the latter. This driving engagement has been effected noiselessly due to the fact that means independent 'ofthe. motor have been employed for moving the'driving discs against'the'driven disc before the motor is connected with the current source. Then when the motoriscauseol to operate it produces noiselessly-a pressure between the driving and driven discs suflicien't for enginestarting purposes.

When the engine becomes self operative and attainsa speed such that the linear speed of the driven disc 35 as effected by the engine exceeds the linear speed ofthe driving discs 33 and 34 as effected by the'starting motor, driving engagement between the driving and driven discs of the starter drive is automatically released. This is accomplished that due to the fact that as the driven disc35 tends to run ahead of the driving discs 33 and '34, the disc 34 tends to screw itself away fromthe disci3fi, and thus permit separation of the driving discs from the driven disc. After the engine starts the electromagnet is automatically deenergized bythe opening of the automatic switch H0. The suction producedin the engine intake when operating will be sufficient to raise the diaphragm H3 against the action of the spring H5, thereby separating contact H4 from contacts H36 .and I111. The spring 9| will then be released to effect movement of the parts 85, 82, 84 and i0 toward the right as viewed in Fig. 2. The spring 16 willalso be released so as to move the upper end of the lever 10 toward the right returning it to its normal position. In this way the engine starter drive parts are restored to normal position as shown in Figs. 1, 2, 3, and 8.

Since the ends 59 of lever Hi bear yieldingly upon the sleeve flange 49 and the internal flange 42 of sleeve 43 will bear yieldingly against the helical splines 4! of the tubular sleeve 3% of driving disc 34. Therefore, since the sleeve 43 .is yieldingly urged toward the left the driving disc 33 will be yieldingly. urged against the driven disc 35; and, since the driving disc 34 is caused to rotate by the sleeve 43 under the action of yielding pressure, the driving disc 34 will be yieldingly pressed against the driven disc 35. Therefore both driving discs are urged by means independent of the motor against the driven disc with yielding pressure. This is desirable for the purpose of compensating for wear of the friction Surfaces of the driving and driven discs. There is another purpose which is important. If the engineshould make a weak or false start and fail to attain a speed sufiicient to insure self operation, the spring 76, being then. held under pressure greater than normal by the electromagnet, an actuating force is. thereby stored in the spring it which tends to maintain the preliminary contact between the driving discs and the driven discso that, if thereis any tendency to relievepressure between the driving and driven discs during a false or weak start of the engine, this tendency will be counteracted by the tendency of the spring 16 to urge the driving discs almost instantaneously back into cooperative relation with the .drivendiscs. In other words, the spring 13 forms a function analogous to that performed in the conventional one way or overrunning clutch by .thesprings which :are provided-reach for urging a clutch roller into wedging engagement between the clutch cam and the clutch shell. Thus when the engine attempts to start on its own power and tends to release the driving engagement between the driving and driven discs and then fails to attain a speed sufficient to maintain self operation, the starting motor drive is at all times ready to pick up the load of cranking the engine instantaneously.

The electromagnetic means which. operates independent of the motor to cause the driving discs to be pressed against the driven discs before the motor is operated is not only a convenient means for preconditioning the starter drive but is one which is well adapted to cooperate with the starter drive of this type. It requires a relatively small force to move the driving disc 33 from its position shown in Fig. 8 to that shown in Fig. 9 where it engages the driven disc 35 and it requires a substantially greater force to move the driving disc 34 into engagement with the driven disc 35 and to effect compression of spring 16 beyond its normal state of compression. The electromagnetic device is well adapted to provide the actuating forces which are required. At first the attraction upon the solenoid armature 82 is relatively small but the force required to move the driving disc 33 toward the left is relatively small. As the solenoid armature 82 approaches the core 83 the attraction increases. greatly to give the necessarily greater force required to move the driving disc 34 against the driven disc 35 and to compress the spring 16 beyond its initial state. It is also necessary that the starter switch contact 95 be pressed against the stationary contacts 98 and 91 with a pressure sufficient to insure a good electrical contact. The electromagnet is also well adapted to give this final pressure which is needed between the starter contacts in the starter switch. During final movement of the solenoid armature 82 toward the left when the air gap between the armature and core is closing up the pull upon the armature increases tremendously and is. sufficient not only to effect the desired movements of the engine starter drive but also to compress the spring 81 beyond its initial state of compression and to force movable contact 95 firmly against the stationary contacts 96 and 91.

The electromagnet is so constructed as to efiect a pull on the armature 82 sufficient to make good electrical contact between the contacts in the starter switch. The magnetic pull required for closing the switch properly is greater than that sufficient for preconditioning the engine starter drive prior to actual operation of the motor.

As undue pressure between the driving discs and the driven disc prior to operation of the motor is as undesirable as insufficient pressure the spring 16 operates while the motor switch is closed to limit the force which can be applied by the electromagnet to the shifting lever 10. The spring 16 is so designed that upon being deflected a certain distance by the armature 82 when closing the motor switch the spring will exert the proper force upon the lever 10 tending to rotate it clockwise about its pivotal connection with the link 84. In this way the spring 16 operates not only as a spring exerting yielding pressure upon the shifting collar flange 49 for the purposes herein specified but spring 16 operates also as a means for limiting the amount of pressure which can be effected by the electromagnet.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form,

it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. For use in an engine starting apparatus having a starting motor adapted to operate the engine to be started, a starter drive through which said motor operates the engine and having, in combination, a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine, a rotatable element operable by the starting motor and providing one of the driving discs, a tubular member about said element and providing the other driving disc, and means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including camming provisions formed upon a cylindrical surface of said element and upon the cooperating cylindrical surface of said tubular member, and said starter drive having means adapted to be acted upon by a force other than that of the starting motor to effect an initial movement of said driving discs for engagement with said driven disc.

2. For use in an engine starting apparatus having a starting motor adapted to operate the engine to be started, a starter drive through which the motor operates the engine and having, in combination, a pair of driving discs adapted \for engagement with opposite faces of a driven member, and said starter drive having means 4 adapted to be acted upon by a force other than that of the starting motor to effect an initial movement of said driving discs for engagement with said driven disc.

3. For use in an engine starting apparatus having a starting motor adapted to operate the engine to be started, a starter drive through which the motor operates the engine and having, in combination, a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine, a rotatable element operable by the starting motor and providing one of the driving discs, a tubular member about said element and providing the other driving disc, and means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including a row of bearing balls received by mating helical races formed in the cooperating surfaces of said rotatable element and said tubular member, and said starter drive having means adapted to be acted upon by a force other than that of the starting motor to effect an initial movement of said driving discs for engagement with said driven disc.

4. For use in an engine starting apparatus 'having a starting motor adapted to operate the engine to be started, a starter drive through which the motor operates the engine and having, in combination, a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of the starting motor and to be driven thereby, a tubular member about the tubular shaft and providing the other driving disc, and means for effecting relative axial movement between said driving discs in response .to rotary move- .which themotor operates the engine and having, in combination, a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine, a tubular shaft providing one of the driving'discs and .adapted to be mounted upon the armature shaft ofthe starting motor and to be driven thereby, a tubular member about the tubular shaft and providing the other driving disc, and meansfor effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including coacting screw thread provisions formed externally of the tubular shaftand internally of said tubular member, and said starter drive having means adapted .to be acted upon by a force other than that of the-starting motor to effect an initial movement of said driving discs for engagement with said driven disc.

6. ,For use in an engine starting apparatus having a starting motor adapted to operate the engine to be started, a starter drive through i which the motoroperates the engine and having, in combination, a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine, a tubular shaft providing one of the driving discs and adapted to be mounted upon thearmature shaft of the starting motor and to bedriven thereby,.a tubular member about the tubular shaft and providing the other driving disc, and means for effecting relative axial movement between said driving discs in response to rotary movement of one relative tothe other, said means including a row of bearing balls received in mating helical races formed on the cooperating surfaces of said tubular shaft and tubular member, and, said starterdrive having means adapted to be acted upon by a force other than that of the starting motor to eifectianinitial movement of said driving discs for engagement with said driven disc.

7. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a starting-motoroperated shaft providing one of the driving discs, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including camming provisions formed upon the cylindrical surface of the shaft and upon the inside cylindrical surface of said tubular member and a shifter sleeve having a longitudinal-spline connection with the shaft and a helical-spline connection with the tubular member and adapted to cooperate with a device for moving the sleeve longitudinally.

8. In an engine starter, the combination of a pair of driving discs adapted forengagement with opposite faces of a driven disc connected with the engine to be started, a starting-motor-operated shaft providing one of the driving discs, .a tubular member surrounding the shaft and providing the other driving disc, means for effecting .relative axial movement between said driving discs in response to rotary movement ofone relative to the other, said means including coasting screw thread provisions formed externally of the shaft and internally of the tubular member and a shifter sleeve having a longitudinal-spline-connection with the shaft and a helical-spline-connection with the tubular member and adapted to cooperate with a device for moving the sleeve longitudinally.

9. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a starting-motor-operated shaft providing one of the driving discs, a tubular member surrounding the shaft and providing the other driving disc, means for. effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including a row of bearing balls received by mating helical races provided by the shaft and tubular-member and a shifter sleeve having a longitudinal-spline-connection with the shaft and a helical-spline-connection with the tubular member and adapted to cooperate with a device for moving the. sleeve longitudinally.

10. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor-and tobe driven thereby, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including camming Iprovisions formed uponthe outside cylindrical surface of, the shaft and upon the inside cylindrical surface of the tubular member and a shifter sleeve having a longitudinal spline connection with the shaft and a helical-spline-connection .with the tubular member and adapted to cooperate with a device for moving the sleeve longitudinally.

11. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disoconnected with the engineto be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor and to be driven thereby, a tubular mempair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor and to be driven thereby, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means includnig a row of bearing balls received by mating helical races provided by the shaft and tubular member and a shifter sleeve having a longitudinal-spline-connection with the shaft and a helical-spline-oonnection with the tubular member and adapted to cooperate with a device for moving the sleeve longitudinally.

13. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a starting-motor-operated shaft providing one of the driving discs, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including camming provisions formed upon the cylindrical surface of the shaft and upon the inside cylindrical surface of said tubular member, and means independent of the starting motor for causing the driving discs to engage the driven disc before the motor operates.

14. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a starting-motor-operated shaft providing one of the driving discs, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including coacting screw thread provisions formed externally of the shaft and internally of the tubular member, and means independent of the starting motor for causing the driving discs. to engage the driven disc before the motor operates.

15. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a starting-motoroperated shaft providing one of the driving discs, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including a row of bearing balls received by mating helical races provided by the shaft and tubular member, and means independent of the starting motor for causing the driving discs to engage the driven disc before the motor operates.

16. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor and to be driven thereby, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including camming provisions formed upon the outside cylindrical surface of the shaft and upon the inside cylindrical surface of the tubular member, and means independent of the starting motor for moving the tubular shaft longitudinally to cause its driving disc to engage the driven disc and for rotating the tubular member to cause the driving disc of said tubular member to engage the driven disc before the motor operates.

17. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor and to be driven thereby, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary mqvlement of one relative to the other, said means including coacting screw thread provisions formed externally of the shaft and internally of the tubular member, and means independent of the starting motor for moving the tubular shaft longitudinally to cause its driving disc to engage the driven disc and for rotating the tubular member to cause the driving disc of said tubular member to engage the driven disc before the motor operates.

18. In an engine starter, the combination of a pair of driving discs adapted for engagement with opposite faces of a driven disc connected with the engine to be started, a tubular shaft providing one of the driving discs and adapted to be mounted upon the armature shaft of a starting motor and to be driven thereby, a tubular member surrounding the shaft and providing the other driving disc, means for effecting relative axial movement between said driving discs in response to rotary movement of one relative to the other, said means including a row of bearing balls received by mating helical races provided by the shaft and tubular member, and means independent of the starting motor for moving the tubular shaft longitudinally to cause its driving disc to engage the driven disc and for rotating the tubular member to cause the driving disc of said tubular member to engage the driven disc before the motor operates.

19. In an engine starter, the combination of a tubular shaft adapted to be mounted upon the armature shaft of an engine-starting-motor and having a longitudinal-spline connection therewith, a tubular member surrounding the tubular shaft and having a screw-thread connection therewith provided by a row of bearing balls received by mating helical recesses provided by said tubular parts, a pair of driving discs adapted to engage a driving disc connected with the) engine to be started, said driving discs being provided, respectively, by said tubular parts, a shifter sleeve surrounding the tubular member and having at one end an internal annular flange which has a helical spline connection with the outside cylindrical surface of the tubular member and having at the other end an external annular flange for engagement with a shifting device, a member attached to the tubular shaft and having parts projecting into longitudinally extending slots provided in the shifting sleeve, and a. helical coil spring located between said member attached to the tubular shaft and the internal annular flange of the shifter sleeve.

JOHN B. DYER.

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