US2067708A - Electric clock - Google Patents

Description

Jan. 12, 1937. HAMMOND 2,067,708

ELECTRIC CLOC K Filed Dec. 2, 1931 2 Sheets-Sheet 1 Z012 6.5 1 6 Invert Z??? Zazzrams %/7/707(67 L. HAMMOND ELECTRIC CLOC K Jane 12, 1937.

' Filed Dec. 2, 1951 2 SheeLs-Sheet 2 @ZiQ/a/M 6' Patented Jan. 12, I937 UNiTED STATES PAT OFFICE ELECTRIC CLOCK Application December 2, 1931, Serial No. 578,426 .38 Claims. (or. 58-26) My invention relates generally to electric clocks and more particularly to the provision of improved means for maintaining the clock in operation during interruptions in the supply of current to the clock.

It is one of the objects of my invention to provide a synchronous motor driven electric clock with improved means for maintaining the clock mechanism in operation during intervals of current interruption. I

A further object of my invention is to provide an improved auxiliary means for maintaining a synchronous motor driven electric clock in operation during intervals of current interruption, which means may be manually wound up and by the degree to which it has unwound indicate the aggregate duration of current interruptions.

A further object is to provide an improved auxiliary drive mechanism for synchronous motor driven clocks which will be operative to cause the motor to fall into step at the conclusion of a current interruption.

A further object is to provide a synchronous motor operated electric clock with an auxiliary drive mechanism and governing mechanism which is simple in construction, will not interfere with the normal operation of the clock and which may be economically manufactured.

A further object is to provide an electric clock having auxiliary spring motor driving mechanism with means for automatically rewinding the spring motor.

Other objects will appear from the followin description, reference being had to the accompanying drawings, in which Fig. 1 is a diagrammatic elevational view of the activating mechanism of a synchronous motor driven clock incorporating my invention;

Fig. 2 is a developed transverse sectional view thereof;

Fi 3 is a vertical sectional view thereof taken on the line 33 of Fig. 1;

Fig. 4 is a fragmentary front elevational view 7 showing the rewind indicator;

clock will stop if the supply of current is intervention the mechanical escapement mechanism is driven by a nually wound spring motor. In a modified form the spring is rewound by power derived from the synchronous motor. The construction disclosed in said application (as well as r in the said modified form disclosed herein) operates automatically and, unless the duration or a current interruption exceeds the interval during which the spring motor will drive the mechanical escapement or governing mechanism, will main- 10 tain the clock in uninterrupted operation throughout the lite thereof.

My preferred construction will, however, be operative to maintain the clock in operation only throughout a number of current interruptions, the cumulative duration of which does not exceed the length of time which the spring motor will drive the governor or escapement mechanism. After the spring motor has become unwound the rupted. Q

It is, however, feasible in using a manually wound spring motor greatly to increase the power which may be stored in the motor as compared with the spring motor of my invention disclosed g in the aforesaid application and, by providing a mechanism to indicate when it is necessary to rewind the spring motor, very satisfactory results may be obtained.

In many localities the current interruptions are of but short duration and it is only upon very rare occasions that such interruptions will exceed a half an hour in length. ZBy-my present invention the spring motor may readily be constructed to store sufficient power to run the clock for practically any desired period of time, although to maintain the size of the motor well within the limits of commercial practicality, I have found it sumcient to design the spring motor so that it will drive the mechanism for a period of approximately three hours.

That the clock owner may readily determine when it is necessary to rewind the clock, I have provided a rewind indicator which not only indicates whenthe spring is entirely unwound, but also serves to indicate when the spring is only partially unwound and indicates the extent to which it is unwound.

For the sake of clarity, the drawings show the invention diagrammatically. Referring to Figs. 1 to 4, the clock is mounted upon a pair of plates l0, l2 which may be secured together in spaced relation in any suitablemanner. A coil l4, connected to a suitable source of alternating current, is wound upon a laminated core 16, the latter having pole pieces I8 and 20 secured thereto. These pole pieces are toothed for cooperation with a correspondingly toothed rotor 22 which is fixed on a rotor shaft 24. The shaft 24 projects through the rear frame plate I2 and has a frame 28rotatably mounted thereon, the frame being, however, mounted to rotate with the shaft 24 by means of a wire spring 28 which projects through a diametrical hole in the shaft 24 and the ends of which are loosely anchored in the frame 26. A weight 30 is secured at the end of a leaf spring 32 which is fastened to a sidewardly extending lug 40 formed on the frame 28, the weight 30 being normally held against a step 42 by the resiliency of the spring 32, the latter force being adjustable by means of an adjusting screw 44.

The end of the leaf spring 32 is adapted to be moved outwardly under the influence of centrifugal force and, when the shaft 24 has attained a predetermined speed of rotation, to strike the end of a resiliently mounted stop 46. This blow robs the rotating frame and all parts moving therewith of a predetermined amount of a kinetic energy, causing the frame and its associated parts rapidly to decelerate to a predetermined mini mum speed. This mechanism is substantially identical with that disclosed in my aforesaid copending application and it is therefore believed to be unnecessary to describe it in further detail herein, since it may be replaced by other suitable mechanical speed governing mechanism, operating upon the same general principle.

The shaft 24 has a pinion 40 rigidly secured thereto, the pinion meshing with a gear 50 carried by a shaft 52. The shaft 52 is connected to a gear 54 freely rotatable upon a shaft 58 through a train of speed reducing gearing comprising pinion 58, gear 60, shaft 82, pinion 84, gear 66, shaft 68, pinion I0, gear I2, shaft 14 and pinion IS.

A ratchet-wheel 18 (Fig. 4) is securedto the shaft 56 and is adapted to be engaged by a socalled silent pawl 80. The gear 54 is thus free to rotate counter-clockwise (Fig. 4) and the rotation of the shaft 58 in a counter-clockwise direction may be utilized to rotate the gear in the same direction.

A spiral coil spring 82 has its inner end secured to the shaft 58 and its outer end anchored to a cross pin 84 secured in the frame l0, I2. A gear 88 is freely rotatable upon the shaft 58 but is prevented from rotating counter-clockwise relative thereto by the engagement of a pawl 88 with a ratchet-wheel 89 fixed to the shaft 58, the pawl being pivotally mounted upon the side of the gear 08. The gear 86 meshes with a pinion 90 secured on a shaft 92. A counterbalanced stop arm 84 is likewise securedto the shaft 92 and is adapted to engage the end 98 of a stop lever 98 which is pivoted on a shaft I00. The stop lever 98 has an armature I02 preferably formed. integrally therewith, the armature cooperating with the field of the coil l4, the plates I0 and 20 having sidewardly bent lugs I04 (Fig. 3) for the purpose of concentrating the magnetic field adjacent the armature. Suitable pads I08 of any suitable shock and noise absorbing material, such as rubber, are secured to the lugs I04. A stop I05 is provided to limit downward movement of the armature I02.

As best shown in Fig. 4, I have provided an indicator to show when it is necessary to rewind the spring 82 This indicator comprises a pinion I08 secured to the shaft 56 and meshing with a gear H0 mounted on a stud II. A portion of the side of the gear H0 is visible through an aperture II2 formed in the dial II4 of the clock. In the position illustrated in Fig. 4, the spring is indicated as approximately half wound. The gear IIO has a colored hand painted or lithographed on its side, the color depth on this band varying by substantially imperceptible degrees of variation in color depth from an extremely light tint to a dark shade. The word rewincl" may be printed upon the most darkly shaded portion of this band in such position as will make it visible through the opening II2 when the spring is entirely unwound. Thus, without great complication, the degree of unwinding is indicated by the color depth of the portion of the band visible through the opening II2.

If desired, the stop arm 94 may be resiliently connected to the shaft 92, as shown in Fig, 5, instead of being rigidly secured thereto as illustrated in Fig. 1. In this construction the pinion 90 is of course fixed to the shaft 92 and has one end of a torsion coil spring H5 secured thereto, the other end of the spring being anchored to the stop arm 94. This modified stop arm mechanism has some advantages which will hereinafter be pointed out.

The shaft 56 projects through the rear frame plate I2 and has a manually engageable key IIB secured thereto, whereby the spring 82 may be rewound. The shaft 14 constitutes the secondhand shaft of the clock. The other bands of the clock may be driven by a suitable speed reducing gear train from this shaft.

In normal operation the winding of the coil I4 will be connected to a suitable source of alternating current of regulated frequency and the motor started by manually twirling the shaft 82 (a thumb-nut 63 being provided for this purpose) or may be started by any suitable automatic starting means which it may be desired to utilize. The rotor will thereafter continue operation as the synchronous motor to turn the hands of the clock. During normal operation the gear 54 will rotate clockwise (Fig. 1, or counterclockwise,'Fig.'4), the pawl 80 and ratchet wheel '18 permitting such rotation without rotation of the shaft 56. The leaf spring 82 will be under sufficient tension to maintain the weight 30 against the lug 42 during such normal operation and the armature I02 will be held against the lugs I04 of the pole pieces I8 and 20 and thereby maintain the toe 96 of the stop lever 98 in position to prevent rotation of the stop arm 94. The spring 82 will of course, through the ratchet wheel 89, pawl 88, gear 86 and pinion 90, tend to rotate the stop arm 94 counter-clockwise (Fig. 1) and thus hold it against the toe 98 of the stop lever 98.

Upon a current interruption the armature I02 will drop, resulting in the removal of the toe 96 from the path of the stop arm 94, permitting the latter to rotate freely. The shaft 56 will thus be driven clockwise (Fig. 1) and through the ratchet wheel 18 and pawl 80 drive the gear 54 counterclockwise (Fig. 4). The gear 54 will, through the speed reducing gear train, drive the rotor shaft 24 counter-clockwise (Fig. 1). The spring 82 will accelerate the rotation of the shaft 24 until it is rotating at sufficient speed to cause the weight 30 to swing outwardly under the influence of centrifugal force sufficient to contact with the end of the resilient stop 46.

Upon striking this stop the rotating system will lose a certain derinite portion of its kinetic energy of rotation and be rapidly decelerated to a speed considerably below its normal synchronous speed. Upon thus decelerating the weight 30 will again be held against its lug 42 by the spring 32. Thereafter the spring 82 of the spring motor will again accelerate the rotor shaft 94 until it again attains a suflicient speed of revolution above its synchronous speed so that the end of the spring 32 again strikes the end of the resilient stop 40. This cycle of operation will be continuously repeated throughout the period of current interruption. It will be observed that, while the shaft 24 does notrotate at a constant speed, its speed will vary between definite maximum and minimum speeds, and by proper adjustment and proportioning of the parts, may be made to maintain a very accurate average speed rotation.

As soon as the supply of current to the coil I4 is resumed the armature I02 will be again drawn to the position in which it is shown in Fig. 1 and the toe 90 of the stop lever 98 swung into position to arrest the rotative movement of the stop arm 94, whereupon the rotor 22 will again take up the load of driving the gear train. Inasmuch as there is a possibility that the supply of current may be resumed at the instant when the rotor shaft is rotating at a speed below its synchronous speed, it may be desirable in some installations, where there is not sumcient play in the gear train, to provide the resilient lost motion connection between the stop arm 94 and the shaft 92 which is illustrated in Fig. 5. With this construction the shaft 56 will not be abruptly stopped but will be retarded more or less gradually so that there will be an assurance that the rotor will be driven through a complete cycle and thus for a moment be moving at substantially synchronous speed before the drive from the shaft 56 is discontinued.

The spring 82 of the spring motor may be made sufiiciently large and powerful to drive the clock mechanism for several hours or, if desired, for longer periods. In order that the owner of the clock may have an indication of how long the clock has been operating while the current is interrupted, the rewind indicator II 0 is provided. If desired, this indicator may be graduated in minutes or hours. The indication thus furnished will be useful, not only to show when the spring motor should be rewound, but will also give an indication of the maximum possible error in the time indication'of the clock.

It will be understood that the speed governing device used to control the speed of operation during current interruptions, like all mechanical speed governing means, is susceptible to slight error. For example, assuming that the maximum possible error is one second per hour and the rewind indicator shows. that the spring motor has driven the clock for a period of five hours, the owner will know that the maximum possible error in the time indication of the clock is five seconds, plus the maximum deviation permitted by the power company supplying the alternating current, the latter being usually one or two seconds.

In Figs. 6 and 7 I have illustrated a modified form of ancillary driving mechanism for the clock in which the spring motor is arranged to be wound by the synchronous motor during normal operation of the clock.

In this modified construction a gear I54 (which corresponds to the gear 54 of the construction of Fig. 1) is loosely mounted on a shaft I56 to which a ratchet-wheel I10 is secured, a pawl I pivoted to the gear I54 forming a driving connec has a friction plate 2! longitudinally slidable thereon but prevented from rotation relative thereto by a pin 2 I Zpassing diametrically through the shaft 208 and fitting in suitable slots 2I4 formed in the sleeve-like hub 2I6 of the friction plate MB. A compression coil spring 2I8 normally holds the friction plate M0 in firm frictional contact with a similar friction plate 220 which is nonrotatably secured to a shaft 222. The shaft 222 has a pinion 224 secured thereto, the pinion being connected by a suitable speed reducing gear train v(comprising gear 226, pinion 228, shaft 23d, gear 232, shaft 234 and pinion 236) with a gear i2d secured to a'spring housing 240. A I

spiral coil spring 202 has its outer end secured to the housing 240 and its inner end anchored to the shaft i5t.

Unwinding the spring I82 is prevented by the electromagnetic armature controlled stop lever B98 in the same manner as disclosed and described with reference to the construction shown in Fig. 1.

During normal operation of a clock equipped with the modification shown in Figs. 5 and 6, the second hand shaft I14 continually rotates the shaft 200 and, unless the spring I02 is fully wound, will, through the frictional connection and the gear train, rotate the housing 240 to rewind the spring. When the spring is fully wound it exerts a sufficient counter-torque to cause slippage between the friction plates 2! and 220. In other respects the operation of the clock, including this automatic rewind mechanism, is the same as previously described.

It will be noted that as the spring I82 unwinds during a current interruption, it will rotate the shaft I14 and thereby at the same time cause rotation of the spring housing 240. This is feasible, however, since the rewinding takes place at a very slow rate as compared with the speed of unwinding.

In the construction shown in Figs. 1, 2, 3 and 4, the spring motor, during normal operation of the clock, does not exert any torque upon the gear train. The gear train may therefore be made of very light and economical construction. Since there is no heavy load upon the gear train during normal operation, the wear upon the bearings will be very small and the useful life of the clock extended. In the construction shown in Figs. 6 and 'l, the gear train is under very slight additional load due to its winding connection with the spring motor, but inasmuch as this connection is through a number of speed reducing gears, the additional load on the main gear train will be small,

While I have shown and described specific emv field core and a rotor for driving said train, a spring motor connected to drive said train, electromagnetically operated means for restraining operation of said spring motor, and mechanical speed-governing means permanently connected to be continuously operated with said gear train and arranged to control the speed of operation thereof only when the gear train is being driven by said spring motor after said eiectromagnetically-operated means has been released upon an interruption in the current supplied thereto.

2. In an electric clock, the combination of a time gear train, a synchronous motor having a field coil and a rotor for driving said train, a manually wound spring motor connected to drive said train, electromagnetically operated means controlled by the field coil of said synchronous motor for holding said spring motor against operation, and continuously rotatable mechanical speed-governing means associated with said gear train and arranged to control the speed of operation thereof when the gear train is being driven by said spring motor after the latter has been released by said electromagnetically operated means.

3. In an electric clock, the combination of a time gear train, a synchronous motor connected to drive said train, a spring motor, means to wind said spring motor, a one way driving connection between said spring motor and said synchronous motor for driving the latter, a stop normally holding said spring motor from operation, and means operable upon an interruption of the current supply to said synchronous motor to remove said stop.

4. In a time keeping device, a synchronous motor having a rotor, a gear train driven thereby, a mechanical continuously rotatable speed governing mechanism having a part rotatable with said rotor, a shaft, a one-way driving connection be-- tween said shaft and said mechanism, a spring motor connected to rotate said shaft, manually operable means for winding said spring motor, a stop shaft geared to said spring motor, a, stop arm secured to said stop shaft, and an electromagnetically operated stop arranged to be moved into position to arrest said stop arm when current is being supplied to said synchronous motor, whereby it will permit said spring motor to drive said mechanism and have its speed controlled by said mechanism during the periods of current interruption.

5. In an electric clock, the combination of a synchronous motor having a field coil and a rotor shaft, a speed reducing time gear train driven by said motor, a spring motor connected to the slow speed end of said train comprising an overrunning clutch and arranged to drive said gear train in the same direction as it is driven by said synchronous motor, a continuously rotating centrifugal speed governing mechanism on the rotor shaft of said synchronous motor operable to limit the speed of rotation of said shaft, and electromagnetic means to hold said spring motor against unwinding, said holding means being rendered inoperative upon the interruption of current flow through the coil of said synchronous motor, and said governing mechanism being operative to control the speed of unwinding of said spring motor while said holding means is inoperative.

6. In an electric clock, the combination of a shaft, a rotor of a synchronous motor rigidly mounted on said shaft, field pieces and a field coil for said rotor, a mechanical centrifugally operated speed governing mechanism carried by said shaft and having parts normally rotating therewith, a spring motor shaft, an energy storing spring having one end fixed to said spring motor shaft, 8. pair of gears rotatably mounted upon said spring motor shaft, a one way driving means between each of said gears and said shaft, a time gear train connecting one of said gears with said synchronous motor shaft, a rotatable stop arm operatively connected to the other of said gears, and means operable upon an interuption in the flow of current through said coil to release said stop arm, thereby to permit said spring motor to drive said synchronous motor shaft through said gear train.

7. In an electric clock, the combination of a clock mechanism frame, a synchronous motor mounted upon said frame, said synchronous motor comprising a rotor, a rotor shaft, pole pieces and a field coil; a time gear train driven by said synchronous motor, a centrifugal mechanical speed controlling mechanism operatively connected to the shaft of said synchronous motor,

said mechanism being inoperative to affect the speed of rotation of said synchronous motor when the latter is rotating at approximately synchronous speed, a spring motor, a driving connection including an over-running clutch between said spring motor and said gear train,

means to restrain said spring motor from operation, and means controlled by the interruption of the flow of current through the field coil of said synchronous motor to render said restraining means inoperative.

8. In an electric clock, the combination of a clock mechanism frame, a synchronous motor mounted upon said frame, said synchronous motor comprising a rotor, a rotor shaft, pole pieces and a field coil; a time gear train driven by said synchronous motor, a centrifugal mechanical speed controlling mechanism operatively connected to the shaft of said synchronous motor, said mechanism being inoperative to affect the speed of rotation of said synchronous motor when the latter is rotating at substantially synchronous speed, aspring motor, a driving connection between said spring motor and said gear train, said connection including an over-running clutch means, resilient means to restrain said spring motor against operation, and means operative upon cessation of flow of current through the coil of said synchronous motor to render said restraining means ineffective.

9. In an electric clock, the combination of a synchronous motor having a field coil and a rotor, a gear train driven by said motor, a spring motor, a limited torque driving connection between said gear train and said spring motor whereby the latter may be slowly wound up during operation of said gear train and thereafter maintained wound, an over-running clutch forming a driving connectiombetween said spring motor and said gear train, holding means to pre vent unwinding of said spring motor, means controlled by the magnetic field of said synchronous motor and operable upon an interruption in the current supply to said synchronous motor to release said holding means and permit said spring motor to drive said gear train, and mechanical speed governing means connected to said gear train and arranged to control the speed of operation thereof only during intervals of interruptions of the current supplied to said field coil.

10. In an electric clock, the combination of a synchronous motor having a field coil and a rotor, a gear train driven by said motor, a spring motor, a frictional driving connection between said gear train and said spring motor whereby the latter may be slowly wound up during operation of said gear train, holding means to prevent unwinding of said spring motor, electromagnetic means controlled by the magnetic field of said synchronous motor and operable upon an interruption in the current supplied to said synchronous motor to release said holding means and permit said spring motor to drive said gear train, and mechanical speed governing means connected to said gear train and arranged to control the speed of operation thereof only dur ing intervals of interruptions of the current supplied to said field coil.

iii. In an electric clock, the combination of a time gear train, a synchronous motor connected to drive said train, a spring motor connected to said train so as to be slowly wound thereby, a one way driving connection between said spring motor and said synchronous motor for driving the latter, a stop normally holding said spring motor from operation, means operableupon an interruption of the current supply to said synchronous motor to remove said stop, and a centrifugal governing mechanism operatively connected with said synchronous motor.

12. In an electric clock for household use, the combination of a synchronous motor" having a field coil and a rotor shaft, 9, speed reducing time gear train driven by said motor, a spring motor, a connection between said spring motor and the slow speed end of said train comprising an over running clutch arranged to drive said gear train in the same direction assaid train is driven by said synchronous motor, gearing including a friction slip drive connection connected to, the slow speed end of said gear train to transmit power therefrom to wind said spring motor, a continuously rotating centrifugal speed governing mechanism rotated by the rotor shaft of said synchronous motor, and electromagnetic means to hold said spring motor, said spring motor being operable upon deenergization of said last-named means to drive said gear train through said overrunning clutch and thereby rotate said centrifu-= gal speed governing mechanism, said holding means being rendered inoperative by the interruption of current flow through the coil of said synchronous motor, and said governing mechanism being operative to control the speed of,operation of said spring motor while the latter is operating during intervals of current interruption. I

13. In an electric clock, the combination of a non-self-starting synchronous motor having a rotor, a speed reducing time gear train driven by the rotor '61 said motor, a centrifugal speed governing mechanism operatively connected with said rotor, a spring motor, a frictional slip drive connection between said gear train and said spring motor operative to wind the .latter substantially to its fully wound condition, a stop to prevent unwinding of said spring motor, and electromagnetically operated means associated with the coil of said synchronous motor to render said stop means inoperative.

14. In a. time keeping device, the combination of a synchronous motor, a centrifugal speed governing device connected to rotate with said motor, said device being ineifective to regulate the speed of said motor when the latter is operating at a speed approximating its synchronous speed, a gear train driven by said synchronous motor, a spring motor, and means operative upon an interruption in the current supply to said synchronous motor to cause said spring motor to drive said synchronous motor and governing device through said gear train, whereupon said governing device will be effective to regulate the speed of operation of said spring motor.

15. In a time keeping device, the combination of a synchronous motor, a centrifugal speed governing device connected to rotate with said motor, said device being ineffective to regulate the speed of said motor when the latter is operating at a speed approximating its synchronous speed, a gear train driven by said synchronous motor, a spring motor, an over-running clutch driving connection to transmit powerfrom said spring motor to said gear train, a slip frictional driving connection between said gear train and spring motor for slowly winding the latter, and electromagnetically operated holding means, said lastnamed means being rendered inoperative upon an interruption of the current supply to said synchronous motor, thereby releasing said spring motor for driving said gear train, synchronous motor and governing device, whereupon said governing device will be operative to maintain the speed of operation of said spring motor at a predetermined average speed,

16. In an electric clock, the combination of a time gear train, a synchronous motor connected to drive said train, a spring motor connected to said train so as to be slowly wound thereby, a one way driving connection between said spring motor and said synchronous motor for driving the latter, a resilient stop normally holding said spring motor from operation, a centrifugal governing'mechanism operatively connected with said synchronous motor, and electromagnetic means for holding said stop operable upon an interrup tion of the current supply to said synchronous motor to release said resilient stop and thereby permit said spring motor to drive said gear train, synchronous motor and centrifugal governing mechanism, whereupon said governing mechanism will operate to control the, speed of operation of said spring motor.

1'7. In-an electric clock the combination of a time gear train, a non-self-starting synchronous motor having a rotor for driving said train, a spring motor for driving said train, electromagnetically operated means for restraining operation of the spring motor when a normal current supply is connected to said synchronous motor, and mechanical speed governing means directly connected to said gear train so as to rotate therewith at all times and arranged to control the speed of operation thereof when the gear train is being driven by said spring motor.

18. In an electric clock, the combination of a time gear train, a non-self-starting synchronous motor having a rotor connected with said gear train, a mechanical speed governing device di-- rectly coupled to the rotor and revolving upon the same axis thereof, a manually wound spring motor for driving said gear train, including said governing device, and means for restraining said spring motor when a normal current supply is connected with the synchronous motor and operative to release said spring motor when said normal current supply is interrupted, whereupon said spring motor will be operative to drive said gear train and said speed governing device will operate to control the speed of operation of said spring motor.

19. In an electric clock, the combination of a time gear train, a non-self-starting synchronous motor having a rotor for driving said train, a manually wound spring motor for driving said train, electromagnetically operated means for restraining operation of the spring motor when a normal current supply is connected to said synchronous motor, and mechanical speed governing means permanently connected to said gear train and arranged to control the speed of operation thereof when the gear train is being driven by said spring motor.

20. In an electric clock, the combination of a time gear train, a non-self-starting synchronous motor having a rotor for driving said train, a manually wound spring motor for driving said train, electromagnetically operated means for restraining the operation of the spring motor when a normal current supply is connected to said synchronous motor, and mechanical speed-gowerning means mounted upon the same shaft with said rotor and fixed to turn therewith for controlling the speed of operation of the gear train when said train is driven by said spring motor.

21. In an electric clock, the combination of a time gear train, a synchronous motor having a rotor for driving said train, a manually wound spring motor connected to drive said train, electromagnetically operated means for restraining operation of said spring motor, said means being operative to release said spring motor upon an interruption in the supply of current to said synchronous motor, and mechanical speed governing means having a part directly connected to said gear train so as to rotate therewith at all times and arranged to control the speed of operation thereof only when the gear train is being driven by said spring motor, said mechanical governor and said rotor being p m ently interconnected.

22. In an electric clock, the combination of a time gear train, a non-self-starting synchronous motor having a rotor, a manually wound spring motor, mechanical speed governing means permanently connected with the rotor of said motor so as to rotate therewith, means for causing the application of rotational torque from said synchronous motor to said gear train when current isbeing supplied to the former, and means to cause the application .of rotational torque from said spring motor to said gear train during perlods of current interruption, said last named means being electromagnetically controlled by the current supply, said governing means being constructed to function and control the speed of the gear train only when the latter is being driven by said spring motor, or when the synchronous motor is connected to a source of alternating current the frequency of which greatly exceeds the nominal or normal frequency for which the synchronous motor is designed.

as. In an electric clock or the like, thecombination, with the works, and an electric motor which is not self-starting for driving said works,

of an auxiliary motor, mechanism connecting said electric motor and auxiliary motor for storing power therein, mechanism for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and means set in operation whenever electric current is supplied to the electric motor for blocking said auxiliary motor.

24. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of an auxiliary motor, mechanism connecting said electric motor and auxiliary motor for storlng power therein, mechanism comprising a gearing and a clutch for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and means for arresting said gearing, and means controlled by the electric current supplied to the electric motor for rendering said arresting means inoperative.

25. In an electric clock or the like, thecombination, with the works,. and an electric motor which is not self starting for driving said works, of an auxiliary motor, mechanism connecting said electric motor and auxiliary motor for storing power therein, mechanism comprising a gearing and a clutch for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and an automatically retracted latch controlled by the magnetic field of said electric motor for arresting said gearing.

26. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of a spring motor, mechanism connecting said spring motor with said works and electric motor for driving the same during current interruptions, means set in operation whenever electric current is supplied to said electric motor for blocking said spring motor, and mechanism intermediate said works and spring motor for storing power in said spring motor.

2'7. A device of the character described comprising in combination, a non-self-starting synchronous motor, a timed instrument so connected to said motor as to cause said motor and instrument to rotate together at a speed ratio which is at all times fixed, a spring motor and means for driving said synchronous motor from said spring motor, and means responsive to electric power failure for stopping said spring motor when said synchronous motor is electrically operated and releasing it for operation when the electric power falls.

28. A device of the character described comprising, in combination, a synchronous motor, a clock so connected to said motor as to cause said motor and clock to rotate together at a speed ratio which is at all times fixed, a spring motor, means for driving said synchronous motor from said spring motor and means for connecting said driving means to said synchronous motor, responsive to power line failure to drive said synchronous motor when electric power fails on said synchronous motor, and means for controlling the speed of said spring motor to maintain the speed of said synchronous motor during said power failures at a speed substantially equal to synchronous speed.

29. A device of the character described comprising, in combination, a non-self-starting synchronous motor, a clock so connected to said motor as to cause said motor and clock to rotate together at a speed ratio which is at all times fixed, a spring motor, means for driving said synchronous motor from said spring motor and means for connecting said driving means to said synchronous motor responsive to electric power failure to drive said synchronous motor when power fails on said synchronous motor.

30. A device of the character described comprising, in combination, a synchronous motor, a clock so connected to said motor as to cause said motor and clock to rotate together, at a speed ratio which is at all times fixed, a spring motor, means for driving said synchronous motor from said spring motor during power line failures and means for controlling the speed of said synchronous motor while driven by said spring motor and means responsive to power line failures for restraining the operation of said spring motor while power is on the synchronous motor.

31. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of an auxiliary motor, mechanism for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and means set in operation whenever electric current is supplied to the electric motor for blocking said auxiliary motor.

32. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of an auxiliary motor, mechanism for connecting said auxiliary motor with the works for driv-- ing the same and the electric motor during current interruptions, and means set in operation whenever electric current is supplied to the electric motor for blocking said auxiliary motor.

33. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of an auxiliary motor, mechanism comprising a gearing and a clutch for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and means set in operation whenever electric current is supplied to the electric motor for blocking said auxiliary motor.

34. In an electric clock or the like, the combination, with the works, and an electric motor which is not self-starting for driving said works, of an auxiliary motor, mechanism comprising a ratchet wheel and'a pawl for connecting said auxiliary motor with the electric motor for driving the same during current interruptions, and

means set in operation whenever electric current is supplied to the electric motor for blocking said auxiliary motor.

' 35. In an electric clock or the like, the combination with the works and a non-seli-starting electric motor therefor, of an auxiliary drive spring motor ior driving said works and motor:

means set into operation by the stoppage of current to said non-self-starting motor for automatically causing said auxiliary drive motor to drive said works and the non-self-starting motor, so that when the current resumes the non-self-starting motor may be driven by the current; said means also causing the auxiliary motor to cease to drive when the current resumes.

36. In an electric clock, the combination of a time gear train, a non-self-starting synchronous motor having a rotor for driving said train, a spring motor for driving said train, electromagnetically operated means for restraining the operation of the spring motor when a normal current supply is connected to said synchronous motor, and mechanical speed-governing means mounted upon the same shaft with said rotor and fixed to turn therewith for controlling the speed of operation of the gear train when said train is driven by said spring motor.

3'7. In an electric clock, the combination of a time gear train, a synchronous motor having a rotor for driving said train, a spring motor connected to drive said train, electromagnetically operated means for restraining operation of said spring motor, said means being operative to release said spring motor upon an interruption in the supply of current to said synchronous motor, and mechanical speed governing means having a part directly connected to said gear train so as to rotate therewith at all times and arranged to control the speed of operation thereof only when the gear train is being driven by said spring motor, said mechanical governor and said rotor being permanently interconnected.

38. In an electric clock having a time gear train, a synchronous motor for driving said gear train, a mechanical speed-regulating governor fixed to the rotor of said motor, a spring motor, gearing, including an over-running clutch for at times connecting said spring motor with said time gear train for transmitting energy from said spring motor to operate said time gear train when said synchronous motor is inoperative, the speed of said spring motor being regulated by said mechanical governor, and means to hold said spring motor from operation while said synchronous motor is operating efiectively.

LAURENS HAMMIOND.

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