US2665543A - Electromechanical clock - Google Patents

Description

O. H. DZCKE.

ELECTROMECHANICAL CLOCK 2 Sheis-Sheet 1 Filed June 29. 1949 [nimuuuum Hfa INVENTOR Oscar H. Dl'cke W if? iane 12, 1954 G. H. mc

ELECTROMECHANICAL CLOCK 2 Sheets-Sheet 2 F'kecl June '29. 1949 Rm r m N m &

"WU G i Patented Jan. 12, 1954 UNITED STATES PATENT OFFICE Claims.

This invention relates to clock mechanism for very accurately manifesting the passing of time including time-keeping mechanism which measures the passing of time irrespective of an alternating current cessation which is both automatically set and automatically regulated by alternating current of regulated frequency.

At present substantially all alternating current commercially generated has its frequency regulated so that its average frequency correctly manifests the passing of time. There are two shortcomings to such alternating current as a time keeping source. 1) This source of current at times fails; and (2) the frequency is not suificiently constant to measure extremely short intervals of time since it is the average frequency and not the instantaneous frequency that correctly manifests the passing of time.

In accordance with the present invention it is proposed to employ clock mechanism which may be fairly well relied upon to keep accurate time when properly adjusted which is provided with regulating means by the manipulation of which the time keeping speed of the clock may be adjusted, to provide means automatically operated in accordance with the average frequency of an alternating current of regulated frequency to operate this regulating means to a position to cause said clock mechanism to correctly manifest the passing of time and to additionally provide means for at spaced time intervals setting the clock hands of such clock mechanism in accordance with the number of cycles of alternating current that have been supplied since the last setting operation.

Another object of the present invention resides in performing both of these functions with the same synchronous motor.

Another object of the present invention resides in performing the regulating function in a manner so that a regulating function that has once been performed is not interfered with as a result of an alternating current cessation.

Another object of the present invention resides in providing means to bring the synchro nous motor operated mechanism back into chronological synchronism with the clock mechanism after each current cessation.

Another object of the present invention resides in providing setting means which does not interfere with the free and proper operation of both the clock mechanism and the synchronous motor operated mechanism.

Other objects, purposes and characteristics of the present invention will become apparent from 2 the following specification when considered in the light of the drawings in which:

Figs. 1 and 1a show one conventional embodiment of the present invention in a manner to facilitate description of the various mechanisms and their functions rather than the exact construction preferably used in practicing the invention.

Structure.-Referring to the drawings the main spring [0, which may be wound in any suitable way, drives the gear i! which through its shaft 109 drives the pinion Hi2, which is in mesh with gear Hll. Gear it! through the medium of slip clutch I04 drives shaft 193 having secured thereto a gear I05 and a setting arm I35. A minute hand I36 is shown driven by a gear 99 driven by gear 105 at a one-to-one gear ratio. An hour hand I3Ga R. P. H.) is driven by the gear 99 through the medium of the usual hour-hand reduction gearing shown. The gear I05 is also in mesh with gear [06 having the same number of teeth as gear I95. This gear I06 has secured thereto a cam H2 preferably of insulating material. This main spring gear II also drives the pinion I2 which is connected by shaft 9 to gear I3 in mesh with pinion l4. Pinion [4 through shaft [5 drives gear 16 in mesh with pinion I! which through shaft !8 drives escape wheel IS.

The escape wheel 19, tends to oscillate the pallet 29. This pallet is pivoted at 2i and supports two laterally projecting pins 22 located on opposite sides of a flat leaf spring 23. This leaf spring 23 supports pendulum 2d and has its upper end secured to a preferably square threaded shank 25 which has its threads supported by the threads contained in the axial opening of a worm wheel 26. This worm wheel 26 is supported by and the shank 25 is guided in a fixed support 28. It is thus seen that the effective length of the pendulum 23-4 is changed as the worm wheel 26 is rotated. The worm wheel 26 is driven in one direction or the other (and at times remains stationary) by the worm 21 secured to gear 30. Gear 30 is at times driven by pinion 3! driven by friction wheel 33 through the medium of shaft 32. Another friction wheel 34 is pivotally supported in a spider 35 pivoted on a fixed pin 36 on which there is also pivoted a pinion 37 in meshed relation with a gear Ma secured to friction wheel 34. When electromagnet 40 is energized by alternating current (or direct current derived from such alternating current) the spider 35 assumes the position shown and holds the friction wheel 34 in driving The pinion 32' is at times driven by the pinion 2 meshed relation therewith, which pinion 2 is connected to worm wheel it through the nediurn of shaft Q3. Worm wheel-cf; isdr-iven by worm G on shaft whichiaas-bya pin connected to the ring wheel or planet supporting wheel This ring wheel 'll le -provided with stub shafts, which have their axis arranged radially and on which are pivoted planet pinions to. Two bevel gears 5i and-52 .arepivotally supported on sha'ft lt. A worm wheel 53 is secured, to bevel gear '5! and a worm wheelfi i is secured to or integral-with bevelgear 52. Both of these bevel gears-Ell and 52 are in meshed relation with planet pinions til. From this cons ruction it is readily seen that if wormwheels es and Eli are rotatedat clifierent speeds and in opposite directions the ring wheel Al is rotated at a sp-eed'equal to the diirerence of the speed of rotation of worm wheels 53 and 5s, and if rotated at the same speed the ringwheel ll and shaft to remainstaticnary. As shown by the arrowsgthe'worinwheels '53 and are rotated in opposite directions, :the'worrn wheel 53 being driven by theworrn 6!) cut into shaft iii to which worm wheel EZis. connected and the worm wheel 54 by worm "ill on shaft "H. The

worm wheel is driven by worm-63 cut on shaft I t5 having a worm wheel 65 securedzthereto and driven by a worm is cut into shaft .15 or" the escapement clock. Similarly the wormwheel its is driven in the opposite direction by worm 778 out into shaft ll, driven by worm wheel '52, driven by worm is cut into sha'ft'l-l tor synchronous motor SM. The speeds oi'the shafts i l and Hill and the gear ratios from 'these'shaits to the worm wheels Eli and 53 respectively are such that the worm wheels 53 and 513 rotate at the same speed, and in opposite directions whenthe clock. mechanism keeps perfect time and when exactly sixty cycle alternating current is .applied to synchronous motor SM. When these worm wheels 53 and 5t and their'associated bevel gears ill and 5:2 rotate at different speeds the ring wheel ll'will rotate-at'the difierenc'e 'ofthe two speeds to thereby cause operation or the gear train between shaft and pendulum ad.- justing worm wheel 26. These various gear ratios are such that if the'clock mechanism gains one minute in 48 hours /2 minute'per day) the pendulum will be lengthened, 'soas to gain only one-half minute in 48'hours after '8 hours of operation. In other words the gear ratio is such as to make a half correction in 43 hours;

The synchronous niotor SM also sets the clock hands to and 38a associated'with the escapeznent clock mechanism. To perform this setting function the shait'l l of the synchronous motor SM.

is provided with 'a pinion l2! which drives the gear 222 secured to shaft lllssupported'in'fixed bearings 88, 89 and 538. On this shaft is pivotally supported a sleeve I0! which supports gear its and slip ring Hi The shalt 108. supports a preferably square block 926 to which a leaf spring l2? is secured. The other or free end of this leaf spring supports a setting arm E so that the leaf spring liil constitutes a spring bearing fulcrum. During operation of shaft Hit the setting arm E25 is urged against and rides against the fixed spiral cam ltd, it being urged thereagainst by the spring are. At the end of each hour, or other suitable time period as determined by the synchronous .motor operated portion of the clock mechanism, the setting arm 525 snaps off or the leaving end or cam and onto the starting end of this cam and in so doing causes the open v-shaped hammer, constituting two obliquely arranged arms 225d, to set the setting arm I to the proper chronological positionif it doesnot already assume such position.

Each time that an alternating current cessation occurs the setting arm its will discontinue rotating at least so long as the current cessationoontinues. If-itwere to start rotating'when alternating currentflow is resumed itwould not indicate the proper time insofar as the minutes within an hour is concerned. For reason the synchronous'inotor SM and in turn the arm E25 is prevented from rotating until the shaft lee rnanifests'the same chronologicalcondition as does shaft H33. This critical starting of the synchronous motor Sh i accomplished by the snap action contact lit-M 1. The gear which is inmeshed relation with gear Bills-supports'a cam H2 having abeal-zed end ii a, both preferably of insulating material, at the'end of which there is a flexible contact M3. To the shaft N38 is secured an arm lit, preferably of insulating material, having a projecting crank member supportin a spring contact ll l which is locatezl'to ride on the insulated cam ii? and beak HM and which will when it reaches'the end of the beak H211 snap by the end and-momentarily engage the contact H3. This momentary engagement of contacts 2 it and'l i l-oc- 'lClllS when'the shaft its and the sleeve it? as- .sume the same chronological position about the axis of these'eleinents.

On the sleeve iil'l is secured a slip ring Hi3 which is connected by wire M3 to contact H3. Similarly the shaft 595 is provided with a slip ring 109 connected by wire 12% to contact HQ. The contacts H3-l i l constitute a picl in circuit closer for synchronous motor SM, whereas the contact I29 associated with the magnetic circuit of thismotor SM is closed only when the synchronous motor SM is energized and therefore this motor will continue to have its energizing-circuit closed. until an alternating current cessation occurs. The reference character A. C. signifies a source of alternating current having its frequency regulated'so that its average frequency correctly manifests the passing of time. Attention is directed to the fact that the winding of motor SM is connected in multiple with the coil of electro-rnagnet all. If desired this winding and coil may be connected in series. vAlso the contact 129 is a holding contact which is, as shown, closed in response to activation of the magnetic field of'rnotor SM. If desired this contact I26 may be associated with the electromagnet w and closed when the coil of this electro-magnet to is energized, When contact lill is closed both the electro-magnet' lii and the synchronous motor SM are energized directly from the alternating current source, there being no othercontacts in the energizing circuits, and they will both remain energize-:1 until a cessation in the supply of alternating current occurs. When an alternating current cessation occurs both of these energizing circuits are broken by the opening of contact I20 and will remain broken even though the supply of alternating current is restored. It is only in response to the momentary closure of contacts I I3I I4 that the motor SM and/or the electromagnet 40 can be re-energized.

Operation-Let us assume, for the purpose of discussion, that the escapement portion of the clock mechanism has the length of its pendulum so adjusted, presumably in the course of manufacture, so that it runs fast'to an extent of onehalf minute per hour (gains twelve minutes per day). Also, that the synchronous motor SM and electro-magnet 40 are both deenergized because the contacts I I3I I4 have not yet been momentarily closed since the alternating current source was wired to the clock mechanism. Let us also assume that the clock hands I36 and I 360; indicate 11:58 p. m. the correct time and that the synchronous motor mechanism by its clock hand I31 indicates 11:50 p. m. One minute later, namely, when both the escapement portion and the synchronous motor portion of the clock mechanism indicate 11:59 p. m. the contact H4 drops off of the beak II2a down to the low portion of the cam I I2 and in so doin this contact H4 momentarily engages the contact II3. momentary engagement of these contacts H3 and H4 causes energization of motor SM and electro-magnet 40 and causes closure of contact I irrespective of whether this contact I20 is associated with the synchronous motor SM or the electromagnet 40. A pick-circuit is then closed from the source A. C. wires I52 and I52, slip-ring I09, wire I24, contacts H4 and IE3, wire I23, slip-ring IIO, wires I53, I54 and I55 winding of synchronous motor SM wire I56 back to the source A.. C. Also, in multiple with Wires I55 and I56 going to the synchronous motor SM are wires I55a and I56a extending to electromagnet 40. As soon as contact I20 closes the pick-up portion of the circuit just traced and including contacts II3-I I4 is shunted out by a stick circuit branch including wires I5! and I58 and holding contact I20. The synchronous motor portion of the mechanism and including shafts "I4 and I08 and gears I2I and I22 are now operating as well as gear I05 which was always operating. One minute later, namely at 12:00 midnight, the setting arm I25 snaps on" of the leaving end of cam I and in so doing sets the escapement clock portion of the clock mechanism and including shaft I03, gears 09, I05 and I00 and clock hands I36 and I30d.

it should be observed that the gears I0! and 122 as well as the arms IIS and I25 on shaft I08 are not afiected in any way by this setting operation by reason of slip clutch I04 and the idling of gear I00 on shaft I08. In this particular instant the setting arm I already assumed substantially the position mid-way between the two V-portions I25a of the setting arm I25 in that the accumulative error during one minute of operation is very small and little change in the positions of clock hands I36 and I 26a took place. When the setting arm I35 is slightly toward one side or the other an effective setting operation will take place.

One hour later, namely at 1:00 a. m., as indicated by the synchronous motor clock-hand I37 the clock hands I 35 and I 36a indicate about 29 seconds past one oclock in the morning. They This U would have indicated about 30 seconds past one oclock were it not for the fact that the escape ment portion of the clock mechanism keeps slightly better time than it did formerly in that the pendulum 24 has been lengthened a little during the past hour. This was accomplished because worm wheel 53 rotated a little faster than worm wheel 54 and in so doing rotated the ring wheel 4'! in a direction to lengthen the effective length of the leaf-spring constituting part of the pendulum 2324. In this connection it should be remembered that the electromagnet 40 was energized for the past hour and therefore held the friction wheels 33 and 34 in driving engagement so that the rotation of rin wheel 4'! was eiiectively transmitted, at a greatly reduced speed, to the worm wheel 25 directly above the pendulum. At this instant (1:00 a. in. alternating current time) the setting arm 25 snaps off of the leaving end of cam E30 and onto the starting end of this cam and in so doing sets the clock hands I35 and 1300; backward to an extent of about 29 seconds, and both sets of clock hands now indicate 1:00 a. m. and correct time. Hour after hour, or any other suitable time period, this setting operation is repeated but in each case the escapement mechanism gains less than it did during the preceding hour. At midnight of the second day, namely forty-eight hours after the clock was set manually and wired to the commercial alternating current source of regulated frequency, the pendulum 24 has been lengthened to an extent where the escapement portion of the clock mechanism gains only fifteen seconds per hour instead of thirty, If we assume that no power failure occurs for another six-day period (eight days altogether and a fair assumption) the escapement clock will have been regulated toward correct time keeping to an extent where it only gains one and seven-eighths seconds per hour, but it still indicates correct time at the end of each hour by reason of being set periodically by the synchronous motor mechanism.

Let us now assume that at 12:01 a. at the beginning of the ninth day, an alternating current cessation occurs and that the cessation continues for 29 minutes. When at 12:30 a. in. power comes back on and alternating current is again available nothing in particular happens and so it could just as well have remained off a much longer time. Nothing happens because the alterhating current that is available cannot reach either the synchronous motor SM nor the electromagnet 40. However, at 1:01 as manifested by the escapement clock the spring contact 5 M snaps off of the end of the beak Him and in so doing momentarily engages the contact H3 to thereby energize both the synchronous motor SM and the electro-magnet 40 after which both of these electro-responsive devices will remain energized through the medium of closed holding contact I20. Both the escapement portion and the synchronous motor portion of the clock mechanism now manifest the same time, both are however one and seven-eighths seconds fast because the escapement clock was gaining at the rate of one and seven-eighths seconds per hour during the hour when the synchronous motor SM was deenergized and at rest. That is, the time keeping quality of the clock was improved in four two-day periods to gains of 15 seconds, 7% seconds, 3% seconds and 1% seconds per hour. At 2:00 a. as manifested by the synchronous motor portion of the clock mechanism the clock installation.

tafeesgaas J hands i315 tand [35a were again set by the :setting rnechanism i rib-E35 but after such setting fun'ctionthe 'clocl; hands fist-i360, are stillone anld seven-eighths seconds fast because the'synchronous motor SM was started one andseveneighth's seconds before one hour had elapsed after the current cessation started. In other words, if a clock automatically regulated and periodically set in accordance with this invention is installed on a customers premises ex- 'less than one second during'each hour after the tenthday. If, however, a current cessation occurs at the end of the eighth day, as above assumed, the clock mechanism will have the same time keepingcuality but the clock 'mechanism will be one and seven-'eighths seconds fast for reasons above given.

The main spring it may be wound manually by the usual winding key and ratchet holding mechanism or may be wound automatically by any one of the various electric winding mecha nisms well known in the art, or if desired may be wound by the synchronous motor SM through the medium of reduction gearing including a slip clutch. V i

It should be understood that the synchronous motor starting and the clock setting function is not necessarily performed on an hourly basis as specifically disclosed but may be performed on any desired time period basis. Also, other forms of mechanism than that shown may be used.

The exact gear reduction from the differential DF to the worm wheel 26 associated with the pendulum support 23 cannot'be given because the screw pitch in the hole of the worm wheel 26 is a factor, as is also the normal speed of rotation of worm wheels iSand d of the'differential DF. Themost accurate way of stating this gear ratio 'istosay' that it is such as to cause the pendulum to change .in length to an extent that its time keeping error will be corrected, that is, reduced fifty percent for each, say, forty-eight hours of regulation. This correction is purposely made extremely slow so that proper averaging of the alternating current frequency will result and also so that small variations in frequency will produce substanti no effect insofar as adjustment of the'pendulum length is concerned. This phase of the automatic regulating feature of the present clock mechanism is more fully'described in my prior application Serial No. 101334 filed June 29, 1949, to which attention is directed. Stating it briefly the regulating function is carried out so gradually that the escapement mechanism will be adjusted to the average frequency andnot so fast? as to follow variations in frequency.

It should be understood that the timekeeping portion of the present invention is not necessarily an escapement pendulum clock but may be an escapement clock of the hair-spring balancewheel type or may, in fact, be of any suitable construction so long as it has good time keeping ualities and provided that it may beregulated while'in operation.

It should be understood that the setting feature of the present invention may be used'separately'from the regulating feature and vice versa.

Having thus shown and described only one -specific embodiment of the present invention it should 'be understood that the particular embodiment shown has been selected to facilitate a description of the underlying principles of the invention and how'these principles may be carried out inpracticing the invention; and that various changes, modifications and additions may be made in practicing the invention so long as these changes do not depart from the spirit or scope of the invention as defined by the scope of the following claims.

'What'I claim as new is:

1. Time manifesting apparatus comprising;

"clock mechanism including a gear train, a slip clutch, clock hands rotated by said gear train through the medium of said slip clutch, means for driving said gear train tending to drive it at excess speed, governing means for retarding the speed of operationof said gear train, regulating means for controlling the speed limit imposed by said governing means; a source of alternating current of regulated frequency so regulated that its average frequency correctly manifests the passing of time; a second gear train; a synchronous motor for operating said second gear train; means including one contact operated by said clock mechanism and a second contact assuming a position dependent on the position then assumed by said second gear train for at least momentarily connecting said synchronous motor'to said source of alternating current when said second gear train and said clock hands manifest the same time; means including a holding contact for maintaining said synchronous motor connected to said source of alternating current when said synchronous motor has been once energized until a cessation of alternating current occurs; means controlled by said second gear train for periodically setting said clock hands to the same chronological condition as that manifested by the second-gear train as permitted by said slip clutch, and means controlled jointly by said two gear trains for operating said regulating means to an adjusted position relatively slowly to cause said clock mechanism after a relatively long'period to be adjusted to operale at a speed to cause said clock hands to correctly manifest the passing of time as manifested by the average frequency of said alternating current source.

2. Time manifesting apparatus comprising; clock mechanism including a gear train, a slip clutch, clock hands rotated by said gear train through the medium of said slip clutch, means tending to drive said gear train at an excessive speed, governing means for retarding the speed of operation of said gear train, regulating means to control said governing means; a source of alternating current having its frequency so regulated that its average frequency correctly manifests the passing of time; a-second gear'train; a synchronous motor for operating said second gear train; contacts assuming relative positions dependent on the relative positions assumed by said second gear train and said clock hands and closed momentarilywhen said second gear train and said clock hands assume the same chronological condition included in an energizing circuit for said synchronous motor; a holding concal position as that manifested by said second gear train as permitted by said slip clutch; and means controlled jointly by said two gear trains and in accordance with the difference of their speeds of rotation for operating said regulating means to an adjusted position relatively slowly to cause said clock mechanism after a relatively long period to operate at a speed to cause said clock hands to correctly manifest the passing of time as determined by the average frequency of said alternating current source.

3. Time manifesting apparatus comprising, clock mechanism provided with clock hands frictionally connected by a friction slip clutch to said clock mechanism, a source of commercial alternating current having its frequency reguiated so that its average frequency correctly manifests the passing of time, synchronous motor mechanism including a synchronous motor energized from said source of alternating current for periodically setting said clock hands as permitted by said friction slip clutch so long as no current cessation occurs, means for preventing the restarting of said synchronous motor upon the restoration of the alternating current until at an instant one setting period after such current cessation started, and means for maintaining said synchronous motor energized until a cessation of such alternating current occurs.

4. Time manifesting apparatus comprising, clock mechanism including a time shaft, clock hands, a friction slip clutch for driving said clock hands by said time shaft, a source of alternating current having its frequency regulated so that its average frequency correctly manifests the passing of time, a synchronous motor at times connected to said source of alternating current, setting means controlled by said synchronous motor for periodically setting said clock hands as permitted by said slip clutch and only so long as no current cessation occurs, means for temporarily preventing the energization of said synchronous motor after a current cessation and reenergizing said synchronous motor after the termination of such cessation only at an instant when said clock mechanism manifests the same chronological condition as is manifested by said setting means, and means for maintaining said synchronous motor energized until a cessation of such alternating current occurs.

5. Time controlled mechanism comprising, a clock mechanism having a friction clutch and clock-hands frictionally connected to said clock mechanism by said friction clutch and provided with regulating means for regulating its speed of operation, a source of alternating current having its variable frequency regulated so that its average frequency correctly manifests the passing of time, a synchronous motor, a shaft driven by said synchronous motor and rotated at a speed of one revolution in a particular period of time as manifested by the average frequency of said alternating current source during such period of time, a shaft driven by said clock mechanism at a speed of one revolution in the same period of time but as manifested by said clock mechanism, contacts including contacts operated by said shafts and a holding contact for connecting said synchronous motor to said source of alternating current only when said shafts assume the same chronological position and maintaining it connected until and only until an alternating current cessation occurs, setting means controlled by the shaft driven by said synchronous motor for setting said clock-hands as permitted by said friction clutch periodically to the same chronological condition as manifested by the shaft driven by said synchronous motor, and means controlled jointly by said clock mechanism and said synchronous motor for operating said regulating means relatively slowly in accordance with the difference of the times manifested by said clock mechanism and said synchronous motor and after a relatively long period of time cause said regulating means to be adjusted to a condition to cause said clock mechanism to correctly manifest the passing of time as determined by the average frequency of said alternating current source over such relatively long period of time.

6. Time controlled mechanism comprising, clock mechanism including a friction clutch and clock-hands frictionally connected thereto by said clutch and provided with regulating means for regulating its speed of operation, a source of alternating current having its frequency regulated so that its average frequency correctly manifests the passing of time, a synchronous motor, a shaft driven by said synchronous motor and rotated at a speed of one revolution in a particular period of time as manifested by the average frequency of said alternating current source, a shaft driven by said clock mechanism at a speed of one revolution in the same period of time but as manifested by said clock mechanism when its regulating means is correctly adjusted, contacts operated respectively by the two shafts and connecting said synchronous motor to said alternating current source by being closed momentarily when said shafts assume the same chronological rotated 13051131011, holding contacts for maintaining said synchronous motor so connected until and only until an alternating current cessation occurs, setting means driven by the shaft driven by said synchronous motor for periodically setting said clock hands as permitted by said friction clutch, and adjusting means controlled jointly by said clock mechanism and said synchronous motor for adjusting said adjusting means relatively slowly in accordance with the difference of the times manifested by said clock mechanism and said synchronous motor and for operating said regulating means to cause said clock mechanism after a relatively long period of correction to correctly manifest the passing of time as determined by the average frequency of said alternating current source over said relatively long period, and means for rendering said last mentioned means Wholly ineffective to adjust said adjusting means so long as said synchronous motor is deenergized.

7. Time controlled mechanism comprising, time lapse manifesting means driven from a local source of energy including a shaft rotated at a speed of one revolution in a predetermined pe 10d of time as measured by said means and including a friction clutch and clock-hands frictionally driven thereby, a source of alternating current of regulated frequency having its varying frequency so regulated that its average frequency over relatively long periods of time correctly manifests the passing of time, a synchronous motor, a shaft driven by said synchronous motor at a speed of one revolution in said predetermined period of time as manifested by the cycle passage of said alternating current, two contacts supported respectively by the two shafts for connecting said synchronous motor to said source of alternating current closed momentarily when said shafts assumo the same chronological position of rotation, holding contacts for maintaining said motor so 11" connected so long and only so long; as no alter nating current cessation occurs, and setting means controlled by the shaft driven by said synchronous motor for periodically setting said clock-hands to the same chronological position as manifested by the shaft driven by said synchronous motor as permitted by said friction clutch.

8. Time manifesting apparatusv comprising, mechanical time measuring apparatus, electrical time measuring apparatus including aself starting synchronousmotor, and contact mechanisms for allowing the restarting of said synchronous motor after a current cessation only when said mechanical and said electrical time measuring apparatuses assume the same chronological condition, means for maintaining said synchroe nous motor energized until. and only until a cessation of alternating current suppliedto said synchronous motor occurs, and means governed by said electrical time measuring apparatus for setting said mechanical time measuring apparatus periodically.

9. Time manifesting apparatus comprising, mechanical time measuring apparatus, a source of alternating current having its frequency regulated so that its average frequency correctly manifests the passing of time, electrical time measuring apparatus including a self starting synchronous motor at times connected to said source, contact mechanisms for starting said syn.- chronous motor only when said mechanical and said electrical time measuring apparatuses assume the same chronological condition, means for maintaining said synchronous motor energized until a cessation of alternating current supplied to said synchronous motor occurs, and means controlled by said. electrical time measur- 32 mg, apparatusfor periodically setting saidmechanical time measuring apparatus.

10. Time manifesting apparatus comprising,

mechanical time measuring, apparatus, a fric tion slip clutch, clock hands driven by said mechanical time measuring apparatus through themedium of said slip clutch, electrical time measuring apparatus including a synchronous motor,

a source of alternating, current of regulated fife:- quency, contacts controlled respectively by said mechanical time measuring apparatus and said electrical time measuring. apparatus and closed only when said mechanical, tin e measuring apparatus and said electrical time measuring apparatus manifest the same time for initially energizing said synchronous motor from said source, holding contacts for maintaining a hold.- ing circuit for said motor closed until an alternating current cessation occurs, means controlled in accordance with the difference of the time integration measured by said mechanical and said electrical time measuring apparatuses for adjust ing the rate of operation of said mechanical time measuring apparatus and acting relatively slowly seas to cause it to correctly manifest the passing of time as determined by the average frequency of said source applied to said synchronous motor, and means controlled by said electrical time measuring apparatus for periodicallyv setting said clock hands as permitted by said slip clutch.

OSCAR H. DICKE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,328,247 Poole Jan. 13, 1920 2,185,334 Dicke Jan. 2, 19%

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