US2248244A - Engine cranking system - Google Patents

Description

July 8, 1941. B. M. LEEcE lENGINE CRANKING SYSTEM Filed Nov. 18, 1939 ATTORNEYS Patented July 8, 1941 UNITED STATES OPF-FICE ENGINE CRANKING SYSTEM Bennett M. Leece, Shaker Heghts,0hio, assign.-

or to The Leece-NevilleCompany, Cleveland, Ohio, a corporation of Ohio Applcation'November 18, 1939,`Serial No. 305,141

11 Claims.

This invention relates to engine cranking lsystems, and as its principal object aims to provide an improved system of this kind which will function more eiiiciently and reliably than the cranking systems heretofore used.

Another object of my invention is to provide an improved cranking system having means for supplying energizing current tothe cranking motor, iirst, at a relatively low voltage for initially energizing the motor andiengaging the cranking pinion and subsequently at a relatively higher voltage for carrying out the cranking operation, and in Which control switches are operatedautomatically in sequence for Supplying the energizing current to the cranking motor at such different voltages.

A further object of my invention is to provide an improved cranking system, of the character referred to, in which an electric driving means is employed for producing the sequential actuation of the switches.

Still another object of my invention is to provide an improved cranking system, of this character, in which the control for the electric driving means includes a manual switch for initiating the operation ofthe driving means and other switch means for insuring the completion of the cycle of operation of the sequentially actuated switches and the automatic stopping of such driving means upon the completion of the cycle.

Another object of my invention is to provide an improved engine cranking system, ofthe character referred to, wherein the current supply means comprises batteries having terminal connections affording the relatively low and relatively higher cranking voltages and in which a generator for charging the batteries is adapted to be connected therewith or disconnected therefrom by the actuation of the sequentially operated switches.

Yet another object of my invention is to provide an improved engine cranking system having motor driven switch means for energizing the cranking motor at relatively low and high voltages in succession and in which the control for the switch motor prevents the operator from stopping the cranking operation while the cranking motor is being energized at low voltage and also causes the system to be automatically restored to a condition of readiness upon completion of the cranking operation.

Other objects and advantages of my invention will be apparent from the following description when taken in conjunction with the accompanying sheet of drawings, in which:

Fig. 1 is a diagram f illustratingY an engine cranking `system embodying my inventionand'in Which-the active circuits are shown in full lines and-'theinactive circuits are shown iii/'dotted lines;

Figs.v 2 'and' 3 kare diagrammatic' views Vof the same system, but showing the -sameat different intervals-in the cycle'of operation'andalso illustratingbyfulland^dotted lines the active andinact-ive circuits;

Further 'reference-will now-be-made to the accompanying drawing `for lthe' purposeA of describingltheJnovel arrangement of apparatusand improvedfunctioning obtained-in my cranking system and althoughv detailed reference will be made for this purpose to the specificiormA of cranking system' shown in the drawing, it will be understood, of course, that my invention is-not to be regarded as limited tothis particular system, but can be lembodied-in various other similar crank-ing systems and-arrangements. i

In theembodiment of my cranking system illustrated-in Fig;V 1, I show a cranking motor Ill, which maybe of lany suitable construction, and may beadapted for releasabledriving connection with an internal combustion engineto be cranked.

Such releasable driving `connection may comprise the pinionandy gearr arrangement usually employed- -forthis purpose in which a pinion l Gais automatically moved kintofmeslrrwith the ywheel gear `ll upon energization of the'cranking motor and-"is automatically disengaged yfrom the gear and -returned toan inoperative position upon startingofI the engine.

I iindfv it desirable to -initially energize the cranking motor I0 at a relatively low voltage so as to engage the piniony Illa with the gear l l without a yslamming -action or a clashing of the gear teeth, andfto thereafter energize the cranking motorlata relatively higher Voltage for eiectively carrying out the cranking operation. For thus energizing Vthe cranking motor at such low andhigh voltages in succession, I provide a current supply or sourcevaiording the desired'different voltages, and a switch mechanismA l2 for controlling the supply of energizing current to the cranking motor `which includes a manually operable switch I3 for initiating the cranking operation. I

The current supply means may comprise a storage-battery, or preferably, a pair of storage batteries such as thehatteriesy I4-and l5 shown in this instance.n Although I do not Wish to be limitedlto-theluse ofstorage batteries'as the sourceof energizing current for the cranking motor I0, nor to any particular battery arrangement, I iind it desirable to use six-volt current for initially energizing the cranking motor to engage the pinion Ia with the gear I I and to thereafter supply twenty-four-volt current to the cranking motor for carrying out the cranking operation. These voltages can be made available by employing two twelve-volt batteries which are connected in series for the full or twenty-four-volt energization of the cranking motor, as will be explained hereinafter, and at least one of which, in this instance the battery I4, has a tap or terminal I6 for taking off six-volt current for initially energizing the cranking motor. The two twelve-volt batteries I4 and I5 can be charged in parallel by a twelve-volt generator I'I, as will be explained hereinafter, and which can be driven by the internal combustion engine being served by the cranking motor I0.

The switch mechanism employed for controlling the charging of the batteries I4 and I5 and the operation of the cranking motor I may comprise, in addition to the manual switch I3, a plurality of pairs of cooperating contacts or individual switches I8, I9, 2U, 2l and 22 and a switch operating means 23 for producing a timed or sequential automatic actuation of such individual switches. The manual switch I3 may comprise a pair of spaced stationary contacts I3a and I3b and a movable contact I3c which can be moved into engagement with the contact I3a. to initiate the operation of the cranking system, as shown in Fig. 2 and to be explained hereinafter, but is normally held in an ofi position in engagement with the contact I3b by a tension spring I3d, as shown in Fig. 1.

The switches I8 and I9 control the charging circuit for the batteries I4 and I5, and as will be explained hereinafter, are actuated to open the charging circuit before the cranking motor I0 is energized by the actuation of the switches 20, 2l and 22. The switch I8 comprises a pair of cooperating movable and stationary contacts I8a and I8b, the former of which is carried by the arm I8c and is connected to ground by the conductor 24. The stationary contact I8b is connected with the terminal 25 of the battery I5 by the conductor 28. The switch I9 also comprises cooperating movable and stationary contacts I9a and I9b of which the movable contact I9a is carried by the arm I9c and is connected with the terminal 21 of the battery I4 by the conductors 28, 28a and 28h. The stationary contact I9b is connected with the terminal 29 of the battery I by the conductors 30 and 30a. The other terminal 3I of the battery I4 is connected to ground by the conductor 32,

The generator II for charging the batteries I4 and I5 has one terminal thereof connected to ground by the conductor 34 and the other terminal connected with the conductors 28a and 28h through the conductor 35 and a cut-out device 36. This cut-out may be of a conventional form and operates to automatically connect the generator I'I with the charging circuit when the speed at which the generator is driven increases above a predetermined value and to disconnect the generator from the charging circuit so as to prevent a reverseflow of current from the batteries to ground through the generator.

When my cranking system is inoperative or in a condition of readiness, such as that represented in Fig. 1 in which the cranking motor I0 is deenergized, the switches I8 and I9 are closed and a parallel charging circuit is established for the batteries I4 and I5 and, if the generator I1 is being driven at a charging speed, the batteries will be charged thereby in parallel. To render this condition of the system more readily apparent and understandable, Fig. l has been drawn with the active charging circuit in full lines and the other inactive circuits in dotted lines. This charging circuit can be readily traced from the generator I'I through conductor 35, cut-out 36 and conductor 28h to terminal 21 of the battery I4. The return portion of the charging circuit for the battery I4 extends through conductor 32, and through ground and the conductor 34 back to the generator. rlhe parallel portion of this charging circuit for serving the battery I5 extends through conductors 28a and 28, switch I9 and conductor 30 to the terminal 29 of the battery. The return portion of this circuit extends from terminal 25, through conductor 26, through switch I8 and conductor 24 to ground and then through conductor 34 back to the generator.

The switch 2U controls the low or six-volt energization of the cranking motor I0 and comprises a pair of cooperating movable and stationary contacts 20a and 20h, the former of which is carried by a movable arm 20c and is connected with the six-volt tap I6 of the battery I4 by the conductor 38. The stationary contact 20h is connected with one terminal of the cranking motor IU by the conductor 39. The other terminal of the cranking motor may be connected to ground by the conductor 40.

Fig. 2 of the drawing shows the condition of the system just after the operator has started or initiated the cranking operation by movement of the contact I3c of the switch I3 into engagement with the contact |3a and shows the active circuits in full lines and the inactive circuits in dotted lines. In the condition of the system here shown the switches I8 and I9 have been opened to disconnect the battery charging circuit and the switch 20 has been closed and the six-volt energization oi the cranking motor IIJ has just begun. This six-volt circuit can be traced from the tap or terminal IB of the battery I4 through conductor 38 and the contacts 20a and Z'b of the switch 20 and conductor 39 to the terminal of the cranking motor I0. The return portion of this circuit extends through conductor 49, through ground and conductor 32, back to the terminal 3I of the battery I4.

The switches 2I and 22 control the energization of the cranking motor I0 at its full voltage, that is, twenty-four volts in this instance. The switch 2I comprises cooperating movable and stationary contacts 2Ia and 2lb, the former of which is carried by a movable arm 2 Ic and is connected with the conductor 28a by the conductor 28e. The stationary contact 2lb is connected with the terminal 25 of the battery I5 by the conductor 42. The switch 22 also comprises a pair of movable and stationary contacts 22a and 22h of which the contact 22h is carried by a movable arm 22c and is connected with a terminal of the cranking motor by the conductor 43. The stationary contact 22a is connected with the terminal 29 of the battery I5 through the conductor 44 and the conductor 30a.

The circuit for energizing the cranking motor I9 at full voltage is established when the switches 2I and 22 are closed, whereupon the batteries I4 and I5 are connected in circuit with the cranking motor in series relationship to each other and supply twenty-four-volt current to the cranking motor. Fig. 3 of the drawing illustrates this condition of the system in which the switches 2| and 22 are closed and the cranking motor is being energized at full voltage, the active full voltage cranking circuit being shown in full lines and the inactive circuits being shown in dotted lines. This full voltage cranking circuit can be traced from the terminal v21 of the battery I4 through conductor 28h, conductors 28a and4 28e, and then through contactsZIa and 2lb of the switch 2| and through conductor 42 to the terminal of the battery I5. Continuing from the terminalk 290i the battery I5, this circuit extends through conductors 30a and 44, and then through the contacts 22a and 22h ofthe switch .22 and through the conductor 43 to the cranking motor I0. The return portion of this circuit extends from. the cranking motor through the conductor 46 and ground, and then through the conductor 32 back to the terminal 3I of the battery I4.

I have already indicated that the switches I8 and I9 which control the parallel charging circuit forthe batteries I4 and I5 are opened before the actuation of the switches 20, 2| and 22, and also that the switch 2U, which controls the low or six-volt energization of the cranking motor is closed prior to the closing of the switches 2| and 22 which control the full or twenty-four volt energization of the cranking motor. It may also be convenientlyl mentioned at this time that it is desirable to keep the switches I8 and I9 open for the completion of the cranking operation and then close these switches to enable the batteries to be charged by the generator I1 after the engine has been started. It should also be mentioned at this point that the switches 2| and 22 should be maintained open during the time that the switch 20 stays closed for producing the sixvolt energization of the cranking v motorl and should be closed to produce the full or twentyfour-volt energization of the cranking motor substantially simultaneously with, or immediately after, the opening of the switch 2U.

To obtain this desired sequence or timed actuation of the switches I8, I9, 20, 2| and 22, I may employ as the switch operating means 23, a rotatable shaft 46 having cams 48, 49, 50, 5| and 52 thereon for cooperation, respectively, with cam followers 53, 54x` 55, 56 and` 51. These cam followers may be of rounded or other suitable shape and are connected, respectively, with the movable arms |80, ISC, 26C and 22o of the corresponding control switches. The actuating cams may be appropriately shaped and are mounted on the shaft 23 in a relative angular relation such that as the cams are rotated through one revolution the above-explained timed or sequential actuation of the switches I8, IS, 2i), 2| and 22 will take place. The cams are insulated from the shaft 23 by insulating bushings 58 or other appropriate means. Y

The shaft 23 may be rotated by any suitable device or means, and preferably, by a small electric motor 60 which may be connected with this shaft either directly or through reduction gearing 6|. The motor 6D may be one designed to operate on twelve-volt current which may be conveniently supplied thereto from the battery I4, as will be presently explained.

In addition to producing a timed or sequential actuation of the switches I8, I9, 20, 2| and 22, it is also desirable to control the operation of these switches, so that when the cranking operation is initiatedl or started by the operator the complete cranking cycle will be carried through and, upon starting of the engine and release of the contact I3c by the operator, the system will be automatically restored to its initial condition of readiness shown in Fig. 1. In other words, it is desirable to have the switch operating means 23 function in a manner such that whenl the driving motor 60 is started by the operator by the closing of the contacts |30 and |3a of the manual switch I3, it will result in the desired actuation of switches I8 and I9 to open the charging circuit, followed by a closing ofthe switch 20v-to produce the six-volt energization of the cranking motor and this, in turn, followed by the opening of the switch A2|) .and the closing of the switches 2| and 22 to produce the full-voltage energization of the cranking motor. After the full or twentyfour volt energization of the cranking motor has continued for the necessary or desired interval of time and the operator permits the contact I3c of the switch I3 to reengage the contact |31), the motor 60 will cause the switches 2| and 22 to be opened and the system will automatically restore itself to the condition of readiness, shown in Fig. 1, including the closing of the switches I8 and I9 to reestablish the battery charging circuit, and the stopping of the motor 60 with the apparatus in such condition that when the contacts I 3c and I3a are again closed another cranking cycle will be started.

For the accomplishment of the automatic control or operation just explained for the switch operating motor 60, I provide automatically operated switch means 63 which will now be described. This automatic switch means 63 may comprise cam actuated contacts or preferably, as shown in this instance, an arrangement of commutator- like switches 64, 65 and 66 each of which includes one or more contacts mounted on a disk or hub of insulating material 61 connected with the shaft 46 to be driven thereby. The contacts of the switch 64 comprise a stationary contact or brush 68 and an interrupted movable contact ring carried by the disk or hub 61 and formed by the ring sections or segments 69. and 13. The contacts of the switch 65 comprise a stationary contact or brush 1I and an uninterrupted contact ring 12 carried by the insulating disk or hub 61. The contacts of the switch 66 likewise comprise a stationary Contact or brush 13 and an interrupted contact ring carried by the insulating disk or hub 61 and formed by the ring sections or segments 'I4 and 15.

The circuit connections for vthe motor 60, which are controlled by the manual switch I3 and the automatic switch means 63, may include a conductor 28d which is a continuation of the conductors 28a and 282) and connects the terminal 21 of the battery I4 directly with one terminal of the -motor 60. The other terminal of the motor Ellis connected with the movable contact I3c of the manually operable switch I3 by the conductor 16. The stationary contact I3a of the switch I3 is connected with the stationary contact 68 of the switch 64 by the conductor 11 and the stationary contact I3b is connected with the stationary contact 13 of the switch 66 by the conductor 18. The stationary contact 1I of the switch 65 is connected to ground by the conductor 19. The segment 69 of the switch 64 is connected with the ring contact 12 of the switch 65 by the conductor or internal connection 80 and the segment 15 of the switch 66 is also connected with the ring-contact 12 of the switch 65 bya conductor or internal connection 8|.

As above indicated, Fig. 1 shows my charging system in its normal condition with the batteries I 4 and I5 connected with the generator I'I for charging in parallel and at this time the movable contact |3c of the switch I3 is in its 01T position, that is, in engagement with the stationary contact Ia where it may be normally held by the tension spring |3d. When the operator wishes to crank the engine he shifts the contact I3c into engagement with the stationary contact I3a and thereupon starts the switch operating motor G9 which causes rotation of the shaft 46 in a clockwise direction, as indicated by the arrow 83. The energizing circuit thus established for the motor Si) by the closing of contacts I3c and Ia is shown in full lines in Fig. 2. and may be traced from the terminal 2'I of the battery I4 through conductors 28h, 23a and 28d to the motor G and then through conductor 'IB and movable and stationary switch contacts I3c and i3d and through conductor 'I'I to the stationary contact 6B of the switch 84. At this time the segment S9 is in engagement with the stationary Contact E3 and hence the circuit being traced will extend through conductor 30, ring contact I2 of the switch 65 and then through conductor 'I9 to ground and back to the terminal 3| of the battery i4 through the conductor 32.

The clockwise rotation of the shaft 46 by the motor 69 promptly causes the switches I 8 and I of the battery charging circuit to be opened and shortly thereafter causes switch 20 to be closed for the six-volt energization of the cranking motor I3 through the circuit previously traced. Continued rotation of the shaft 4B causes opening of the switch 2B of the six-volt circuit and closing of the switches 2| and 22 for the establishment of the previously traced twenty-four-volt energizing circuit for the cranking motor. At about the same time as, or just after the switches 2| and 22 are closed, the dead segment lil of the switch 64 arrives at the stationary contact or brush S3, and the circuit for the motor 5f: is thereby opened and this motor comes to a stop with the switches 2i and 22 closed and the cranking motor Iii being energized at full voltage, or in other words, with the system in the condition represented in Fig. 3.

When the cranking of the engine has continued for the desired interval, or upon starting of the engine, the operator releases the contact |30 and permits it to return to its off position in engagement with the contact |31). This causes the motor 60 to be reenergized and to resume the clockwise rotation of the shaft 46 causing the switches 2| and 22 to be opened and the cranking motor I deenergized. The motor 60 will continue to run until the dead segment 'I4 of the switch 66 arrives at the contact 'I3 at which time the energizing circuit for the motor 60 will again be opened and the motor stopped with the switch operating means 23 restored to its initial position, as shown in Fig. l. When the contact I3c is permitted to return to its on position at the completion of the full-voltage cranking operation, as just explained, the energizing circuit for the motor Eil will shift from that above traced through the switch 64 to one extending through the switch rIhis latter energizing circuit for the motor B is similar to that traced through the switch 65 except that it now extends from the stationary contact |313 of the switch I3 through the conductor 'I8 to the contact 'I3 of the switch S5, through segment 'I5 of this switch, then through conductor 8| and ring contact 'I2 of the switch E35 and then through contact 'II and conductor 19 to ground.

With the circuit and switch arrangement above described, it will be seen that from the time the operator closes the contacts I3c and I3a of the switch I3, the cranking cycle will be automatically carried out from the opening of the battery charging circuit to the closing of the twenty-fourvolt circuit for the cranking motor I0 and the stopping of the switch operating motor 60 at this point with the cranking motor fully energized. Likewise, it will be seen that when the cranking of the engine has continued for the desired interval, or until the engine starts, and the operator then permits the contact I3c to return to its off position, the switch mechanism 23 will be automatically returned to its initial setting or position, shown in Fig. 1. It will also be seen that the switch and circuit arrangement for controlling the switch operating motor 60 is such that once the operator has started this motor by closing the contacts I3c and I3a, he will be unable to stop the motor 60 at a time when damage might occur, such as when the switch 20 has been closed for the six-volt energization of the cranking motor. If the operator fails for any reason to hold the contact I3c in engagement with the contact I3a until the completion of the cycle or until the engine has been started, no harm will be done to the system because the reengagement of the contact I3c with the contact I3b will permit the motor 60 to continue to run long enough to restore the system to its initial condition of readiness shown in Fig. 1.

It will be understood, of course, that to obtain ie system operation above explained, the movable ring sections or segments of the switches S4 and B6 must be of proper angular length and must be mounted on the insulating disk or hub 61 in the proper angular relation to each other and to the switch actuating cams of the shafts 46, such as the relation shown in the drawing. With this arrangement it will be seen that when the system is in its initial position or inoperative condition, as illustrated in Fig. l, the dead segment 'I4 of the switch 66 has previously come into engagement with the stationary contact 'I3 and the leading end of the long segment 69 of the switch 64 has just come into engagement with the stationary contact 68 so that upon closing of the contacts |30 and I3a another cranking cycle can be started or initiated.

One or both of the batteries I4 and I5 may also be used for other purposes than the operation of the cranking motor I0 and the switch operating motor 60, such as the energization of one or more incandescent lamps as might be desirable when my cranking system is applied to a motor vehicle.

From the foregoing description and the accompanying drawing, it will now be readily understood that I have provided an improved cranking system for internal combustion engines in which the cranking motor can be energized by relatively low and relatively high voltages in succession and such energization will be carried out in an efficient and satisfactory manner by a timed or sequential actuation of a novel arrangement of control switches. It will be seen furthermore that with the arrangement oi switches and the switch actuating means which I have provide-d a cycle of operation is obtained in which the low and high voltage energization of the cranking motor can be had for the desired time intervals and thereafter the switch operating means is automatically returned to an initial position corresponding with a condition of readiness of the cranking system. It will likewise be seen that I have provided a novel control for-the means which drives the switch operating means by which the proper energization of the driving means can be established by the operator and will be maintained for the complete cycle regardless of the subsequent actions of the operator.

While I have illustrated and described my improved cranking system in a more or less detailed manner, it will be understood,l of course, that I do not wish to be limited to the `precise arrangement and functioning herein disclosed, but regard my invention as including such changes and modifications as do not involve a departure from the spirit of the invention and the scope of the appended claims.

Having thus described my invention, I claim:

1. In an engine cranking system, a cranking motor, current supply means having terminals aiording a relatively low voltage for initially energizing the cranking motor and a higher voltage for carrying out the cranking operation, circuit connections between said terminals and cranking motor including a plurality of switches for controlling such connections and the energization of the cranking motor at said low and higher voltages in succession, motor-driven means for causing timed actuation of said switches, circuit connections for the motor of said motordriven means, manually operable switch means in the last-mentioned circuit connections for starting said motor-driven means, and automatically actuated switch means in said last-mentioned circuit connections for stopping said motor-driven means after predetermined operation thereof.

2. In an engine cranking system, a cranking motor, current supply means comprising a plurality of batteries one of which has terminals affording different voltages, a generator for charging said batteries, circuit connections between said generator and batteries and between said batteries and said cranking motor including a plurality of switches operable to control the charging circuit and the energization of the cranking circuit at said different voltages, and motor-driven means for causing timed actuation of said switches.

3. In an engine cranking system, a cranking motor, current supply means comprising storage batteries affording a relatively low voltage for initially energizing the cranking motor and a higher voltage for carrying out the cranking operation, a generator, circuit connections between said batteries and generator and between said batteries and cranking motor including a plurality of switches for controlling such connections, said switches being operable in succession to establish a circuit for energization of the cranking motor at said relatively low voltage, a circuit for energization of the cranking motor at said higher voltage and to establish a circuit for charging the batteries from said generator, means for causing such timed actuation of said switches including an operating means and an electric driving means therefor, and a switchcontrolled circuit for energizing said driving means.

fl. In an engine cranking system, a cranking motor, current supply means comprising storage batteries aiording a relatively low voltage for initially energizing the cranking motor and a higher voltage for carrying out the cranking operation, a generator, circuit connections between said .batteries and generator andbetween said batteries land cranking f motor 'includingfa pluralityy of switches for controllingr such` connections, said switches being operable in succession to establish a circuit for energization of the cranking motor at said'relatively low voltage, a circuit for energization of the cranking motor at said higher voltage and to establish a circuit for charging the batteries from said generator, means for' causing such timed' actuation of said switches including an operating means and an electric driving means therefor, ra circuit for said driving means, and means controlling the lastmentioned` circuit and adapted to cause automatic stopping of the 'driving meansafter predetermined operation thereof.

5. In an engine cranking system, a cranking motor, current supply means comprisinga battery having terminals affording different cranking voltages, a generator for chargingsaid-battery, circuit connections between said generator and battery and between said battery and cranking motor including a vplurality of switches `for controlling such connections, and a motor-'driven shaft having cams thereon for causing sequential actuation of said switches.

6. In an engine cranking system, cranking motor, current supply means having terminals affording a relatively low voltage for initially energizing the cranking motor anda higher voltage for carrying out the cranking operation, circuit connections between said terminals and cranking motor including a plurality of switches for controlling such connections, meansv forfcausing ftimed' actuation of said switches in a given cycle including an operating means and an electric driving means therefor, a circuit for said driving means, a manually operable switch in the -lastmentioned circuit for energizing the same and initiating the operation of said driving means, and other switch means also actuatedA by said electric driving means and arranged for maintaining the driving means energized until completion of said cycle and thereafter causing automatic stopping of the driving means.

'7. In an engine cranking system, a cranking motor, current supply means having terminals affording different cranking voltages, circuit connections between said terminals and cranking motor including a plurality of switches for controlling such connections, a shaft having cams thereon and adapted to be driven for causing actuation of said switches in a predetermined cycle for applying the different cranking voltages to the cranking motor in succession, a second motor for driving said shaft, circuit connections for the second motor including a manual switch for starting the same and other switch contacts driven by the second motor and arranged for maintaining the circuit for said second motor energized until completion of said cycle and thereupon automatically stopping the second motor.

8. In an engine cranking system, a cranking motor, current supply means having terminals affording different cranking voltages, circuit connections between said terminals and cranking motor including a plurality of switches for controlling such connections, a shaft having cams thereon and adapted to be driven for causing sequential actuation of said switches and the return of the cams to an initial position, electric driving means for said shaft, circuit connections for said electric driving means including a switch having a pair of stationary contacts and a contact movable to engage either of said stationary contacts for initiating operation of said driving means, and a pair of movable interrupted timing contacts connected with said stationary contacts and adapted to be driven for causing continued operation of the driving means to complete the sequential actuation of said plurality of switches and the return of said cams to their initial position.

9. In an engine cranking system, a cranking motor, current supply means affording different cranking voltages, circuit connections between said supply means and cranking motor including a plurality of switches for controlling such connections, a shaft having operating connection with said switches and adapted to be driven for causing sequential actuation of said switches and the return of the switches to an initial setting, an electric driving motor for said shaft, circuit connections for said driving motor including a switch having a pair of stationary contacts and a contact movable to engage either of said stationary contacts for initiating operation of said driving motor, and a pair of interrupted timing contacts adapted to be driven by said driving motor and electrically connected with said stationary contacts for causing continued operation of the driving motor to complete the sequential actuation of said plurality of switches and the return of said switches to their initial setting.

10. In an engine cranking system, a cranking motor, current supply means aording a relatively low voltage for initially energizing the cranking motor and a higher voltage for carrying out the cranking operation, circuit connections between said supply means and cranking motor including sequentially operable means for controllingsuch connections, said sequentially operable means comprising a switch means for establishing a circuit for energization of the cranking motor at a relatively low voltage and a switch means for energization of the cranking motor at said higher voltage, motor-driven means for actuating said switch means in succession, circuit connections for the motor of said motordriven means, and switch means of the interrupted contact type included in the last-mentioned circuit connections and actuated by the motor-driven means for timing the operation of the cranking motor at said low and higher voltages.

11. In an engine cranking system, a cranking motor, current supply means comprising storage batteries affording a relatively low voltage for initially energizing the cranking motor and a higher voltage for carrying out the cranking operation, a generator, circuit connections between said batteries and generator and between said batteries and cranking motor including sequentially operable means for controlling such connections, said sequentially operable means comprising a switch means for disconnecting the generator and batteries and subsequently reestablishing a charging circuit therebetween, a switch means for establishing a circuit for energization of the cranking motor at a relatively low voltage and a switch means for energization of the cranking motor at said higher voltage, motor-driven means for causing actuation of said switch means in succession, circuit connections for the motor of said motor-driven means, switch means of the interrupted contact type ineluded in the last-mentioned circuit connections and driven by the motor of said motor-driven means for timing the operation of said cranking motor at said low and high voltages and for stopping said motor-driven means after said charging circuit has been reestablished, and manually operable switch means included in the last-mentioned circuit connections for initiating the operation of said motor-driven means.

BENNETT M. LEECE.

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