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Publication numberUS3233400 A
Publication typeGrant
Publication dateFeb 8, 1966
Filing dateOct 21, 1963
Priority dateOct 21, 1963
Publication numberUS 3233400 A, US 3233400A, US-A-3233400, US3233400 A, US3233400A
InventorsHaydon Arthur W
Original AssigneeHaydon Arthur W
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Resettable clock or the like
US 3233400 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

A. w. HAYDON 3,233,400

RESETTABLE CLOCK OR THE LIKE 3 Sheets-Sheet 1 Feb. 8, 1966 Filed Oct. 21, 1963 INVENTOR. ARTHUR W. HAYDON {.JJ w ATTORNEYS Feb. 8, 1966 A. w. HAYDON 3,233,400

RESET'IABLE CLOCK OR THE LIKE FIG. 4

FIG. 3

INVENTOR. 93 ARTHUR W. HAYDQN ATTORNE YS Feb. 8, 1966 A. w. HAYDON RESETTABLE CLOCK OR THE LIKE 5 Sheets-Sheet 5 Filed Oct. 21, 1963 FIG. 5

INVENTOR. ARTHUR W. HAYDON ATTORNE S United States Patent Ofiice 3,233,400 Patented Feb. 8, 1966 3,233,400 RESETTABLE CLOCK OR THE LIKE Arthur W. Haydon, 83 Point Lookout, Milford, Conn. Filed Oct. 21, 1963, Ser. No. 317,419 21 Claims. (Cl. 58--34) The present invention relates to a resettable clock mechanism or the like, and is intended specifically for, although not necessarily limited to, a novel and improved resettable clock mechanism for incorporation in a masterslave timekeeping system, whereby one or more slave clock units may periodically be reset to a predetermined time indication and subsequently restarted in synchronous relation with a precison controlled master timing unit.

A; variety of timekeeping systems are presently known and available which make use of a master timekeeping unit and a plurality of slave timekeeping units, and in whicli'theslave units periodically are corrected to coincide exactly with the timekeeping of the master unit. Such timekeeping systems find advantageous use for accurate time networks, for example, where the master timekeeping unit is maintained accurately related to standard or observatory time; likewise, the systems may be employed to advantage to provide plant-wide or comrelation with a precision controlled master timing unit. formity of timekeeping is desired, as for punch clocks and the like.

In accordance with the present invention, a novel and improved mechanical mechanism is provided, for particular application as a slave unit in a master-slave timekeeping system, which is of extremely simplified and economical construction, while at the same time being highly reliable in operation. Thus, in accordance with one aspect of the invention, a novel timekeeping mechanism or the like is provided which comprises a plurality of output shafts connected through a predetermined gear reduction mechanism for operation at related speeds (e.g., hour hand and minute hand) in which means are provided for controllably disengaging the output shafts from their respective drive mechanisms to accommodate free rotation of the shafts, and additional means are provided for acting upon the disengaged shafts to return them to predetermined, time-indicating positions, from which they may be restarted in accurately synchronized relation to a master timekeeping device. Thus, the clock of the invention is intended specifically to be reset once during each twelve hour or twenty-four hour period, for example, at which time the hands of the slave timekeeping units are reset to a; specific, predesignated time. Thereafter, upon signal from the master timekeeping device, the clock is restarted from such predesignated time.

One of the more specific aspects of the invention resides in the provision, in a clock or similar mechanism incorporating a substantial gear reduction train, of means for controllably disengaging a plurality of output shafts from driving relation with the gear reduction train, e11- abling the output shafts to be reset individually to predetermined rotary positions, while at the same time maintaining the output shafts and gear reduction train in a synchronized relationship, accommodating smooth remeshing of the various gears upon re-engagement of the gear reduction train. This advantageous result is achieved, in accordance with the invention, by providing novel and simplified arrangements for disengaging certain gears of the train, while maintaining other gears in mesh, and by so designing the disengaged gears, in relation to the various gear reductions involved in the gear train, that proper alignment of the disengaged gear pairs is assured, even though the output shafts of the mechanism are returned independently to predetermined positions.

Another specific aspect of the invention resides in the provision of novel magnetic reset means, including polarized magnets of specifically novel form acting between fixed parts of the mechanism frame and the respective output shafts and operative, when the output shafts are disengaged from the gear reduction train, to urge the shafts individually to rotate into precise, predetermined rotary reset positions. The magnetic reset facilities constantly influence the output shafts of the mechanism, without involving any actual physical contact between parts and without affecting the normal operation of the clock. However, when the outut shafts are disengaged from the driving train and are capable of free rotation, the polarized magnet pairs immediately return the shafts individually to their predetermined reset positions.

As a further specific aspect of the invention, a resettable clock or similar mechanism is provided, which includes novel and simplified reset shift means, whereby the output shafts of the mechanism may be disengaged from the driving gear train to accommodate independent resetting rotary movement of the various output shafts. The mechanism of the invention includes a movable member, for shifting selected gears of the reduction train out of driving mesh, and a solenoid for controlling the shifting movements of the member, The solenoid is actuated in conjunction with the actuation of an input electric motor for the mechanism, such that the solenoid is actuated to effect engagement of the drive system when the motor is energized, and the solenoid is de-energized to effect disengagement of the reduction train when the input motor is de-energized. However, in accordance with the invention, the work input necessary to effect engagement and. disengagement of the reduction train is not derived from the solenoid, but is derived from the motor itself. Significantly, this avoids the necessity for the solenoid doing work during its closing or energizing movements, enabling a small and inexpensive solenoid to be employed.

In conjunction with the above-described novel reset shift arrangement, the mechanism of the invention carries a unique magnetic detent arrangement whereby the reset shift mechanism, when driven into a predetermined position by the input motor, passes through an overcenter position and is advanced further and held in an operative condition through the cooperation of a magnetic detent arrangement and the reset solenoid. Subsequently, when the mechanism is released by the solenoid, the magnetic detent arrangement serves to advance the mechanism into a position in which it is drivingly engaged with the input motor, in readiness for a restarting operation.

For a better understanding of the above and other novel and advantageous features of the invention, reference should be made to the following detailed description and to the accompanying drawings, in'which:

FIG. 1 is a longitudinal cross-sectional view of a slave timekeeping mechanism incorporating the various features of the invention;

FIG. 2 is a back elevation of the mechanism of FIG. 1, with the cover removed and with parts broken away for clarity of illustration;

FIG. 3 is an enlarged, fragmentary, cross-sectional view taken generally along line 33 of FIG. 1 illustrating the mechanism in an operating or engaged condition;

FIG. 4 is an enlarged, fragmentary, cross-sectional view similar to FIG. 3, illustrating parts of the mechanism in a reset or disengaged condition;

FIG. 5 is an enlarged, fragmentary, cross-sectional vie/w taken generally along line 5-5 of FIG. 1; and

FIG. 6 is a simplified, schematic representation of an electrical circuit arrangement employed in the control of the mechanism of FIG. 1.

Referring now to the drawings, and initially to FIG. 1 thereof, the reference numerals 12 designate frame plates which are connected together in a conventional manner by spacer posts 13 and bolts 14 to form a rigid, three-dimensional frame structure. An indicator, such as a clock face 15, is secured to the front frame plate 10, and a cover or housing 16 surrounds the entire frame and the mechanism contained therein.

The specific mechanism illustrated is a slave clock unit provided with second, minute, and hour hands 17-19 mounted respectively on concentric shafts 2042. The innermost or second hand shaft 20 may be a solid, elongated shaft and advantageously is journalled in an elongated tubular bearing 23 anchored at its innermost end in the frame plate 11 and projecting forlward beyond the clock face 15. The intermediate or minute hand shaft 21 is of tubular form and of shorter length than the second hand shaft 20, and is so constructed as to. surround and be supported internally by the tubular bearing 23. The hour hand shaft 22 surrounds the minute hand shaft 21 and is supported for rotation by an anti-\friction-bearing 24 mounted in the front plate 10 of the frame structure. The respective shafts 2022, referred to herein as output shafts, are of graduated length, such that the minute hand shaft 21 projects beyond both ends of the hour hand shaft and the second hand shaft 20 projects beyond both ends of the minute hand shaft, all in accordance with known principles of clock construction.

Each of the output shafts 20 22 has securedlto its inner end a drive gear, designated bythe numerals 25-27. Likewise, each of the higher speed output shafts, that is, the second hand shaft 20 and the minute hand shaft 21, carries a reduction pinion, the latter beingdesignated by the reference numerals 28, 29.

In a typical clock mechanism, the second hand shaft \20 is driven at a rate of one revolution per minute, by appropriate input to the drive gear 25. The minute hand shaft 21 is designed to rotate at a'rate of one revolution per hour, and this-is brought about by effecting a 60:1

gear reduction ratio between the second hand shaft 20 and the minute hand shaftZI. To this end, the reduction pinion 28, attached to the inner end of the second hand shaft 20, drives a gear a of a gear and pinion speed reduction combination 30, while the pinion 3-1 of the combination engages the drive gear 26 for the minute hand shaft. The two speed reductions derived through the .gears .28, 30a and the gears 31, 26 are so calculated as to achieve the desired-60:1 reduction ratio.

Likewise, the hour hand shaft 22 of the clock mechanism is designed to rotate at a rate of one revolution for each twelve (or in some cases twenty-four) hours, and this is achieved by employing a second gear and pinion speed reduction combination 32, with the gear 33 of the combination meshing with the reduction pinion 29 carried by the minute hand shaft and the pinion 34 of the combinationmeshing with the. drive gear 27 of the hour hand shaft 22. i

V For driving the gear 25 and'the second hand shaft 20, there advantageously is provided an input drive motor 35, which is secured to the back frame plate 12 and has its rotor shaft 36 and output pinion 37 projecting forward through the frame plate. Advantageously, the motor is a synchronous inductor motor of the general type described and claimed in the W. D. Riggs Patent No. 3,014,141, granted December 19, 1961,'and, in any event, is of a type that, when de-energized, stops immediately through residual magnetic effects or otherwise, and then drives a speed reduction combination 38, including a gear 39 and pinion 40, and the pinion 40, in turn, drives a further speed reduction combination 41, including a gear 42 and pinion 43. 1 The pinion 43 meshes withthe drive gear 25 fixed to the end of the second hand shaft 20.

In a typical, practical embodiment o-fthe invention, the motor 35 may be designed for synchronous operations at 250 revolutions per minute. In such case, the three speed reduction steps achieved through the gears 37 and 39, and 42, and 43 and 25 are calculated to provide the desired overall speed reduction of 250:1. Thus, in normal operation of the mechanism for ordinary timekeeping purposes, the input motor 35, properly energized from an alternating current source, operates at 250 r.p.rn. to drive the second hand shaft 20 at. one revolution per minute. The minute hand and hour hand shafts 21, 22 are correspondingly driven through their respective gear reduction trains at one revolution per hour and one revolution per twelve (or twenty-four) hours. a

In accordance with the invention, means are provided for controllably disengaging the output shafts 2022 from their respective driving mechanisms, to enable the respec tive shafts to be rotated individuallyto predetermined reset positions. To this end, the respective gear and pinion reduction combinations 32, 30, and 41, for driving the hour, minute, and second hand shafts respectively, are retractably mounted on a common reset shift con trol shaft 44, the various gear and pinion combinations being freely and independently rotatable on the shaft. The control shaft '44 is provided at each end witheccentrically positioned journal pins '45, which are received in bearings 46 in the front and rear frame plates 10, 1'2.-

. In a typical, practical embodiment of the invention, the

journal pins 45 may be offset approximately 0.010 inch from the centerline of the control shaft 44 such that, when the control shaft is rotated through its centerline, which forms the rotational axis for the respectivespeed reduction gear and pinion combinations 32, 30, 41, are shifted through a total displacement of about 0.020 inch. Thus, by appropriate design of at least certain of the gears of the mechanism, disengagement of the respective output shafts from the gear mechanism may be effected by rotating the control shaft 44 through approximately 180 to displace its axis away from the common axis of the output shafts. When this is done, the output shafts are freely and independently rotatable, and, by means subsequently to be described, the respective output shafts are then returned to predetermined rotary reset positions. I

In accordance with one of the significant aspectsof. the invention, the various gear mechanisms involved in the driving of the output shafts are so designed and re-v lated that, when the output shafts aredisengaged and. returned to their respective reset positions, the various. cooperating gear sets are properly oriented for remeshing. Thus, when the control shaft 44 subsequently is rotated.

back through 180 to displace the control shaft axis to-.

output shafts 20-22 have a predetermined mutual relationship, corresponding to a relationship which the shafts would have if interconnected by the gear reduction train;

Thus, for descriptive purposes, with respect to a clock mechanism as an illustrated form .of the mechanism th'e' respective reset positions of the. output shafts must be" valid timekeeping positions, as distinguished from posi-' tions which cannot be assumed by .the.hands of a nor-j mally functioning clock.' As an illustration, the reset, positions may be such that all of the hands 17.1 9 .point directly to twelve oclock, although, as a practical matter,

it usually is desirable to effect reset at some less prominenti time than exactly twelve oclock. Of course, it should be undestood .that'the necessary mutual relationship for proper reset 'is essentially between the output shafts themselves and not the time indicating hands 17-19, which may be adjustably related to the output shafts. However, assuming the indicator hands to be properly adjusted nets 50b, 51b conveniently may be mounted upon the intermediate frame plate 11, while the fixed magnet 52b is conveniently mountedon the front frame plate 10.

, Each of the magnet pairs 5011-5011, 51a-51b, etc., is sharply polarized, such that the movable magnet of each pair is urged into a predetermined rotary orientation relative to the fixed magnet. Thus,.when an output shaft is disconnected from the gear train, by manipulation of the control shaft 44, the shaft is rotated under the influence of the associated magnet pair, until the magnets are aligned in their most strongly attracting relationship, which will determine the predetermined rotationalorientation of the shaft in its reset position.

Initial alignment of the respective magnet pairs should be elfected while the various output shafts are engaged with the reduction train, so that all output shafts have an aligned or reset position which is consistent with proper meshing of all gears of the train. With the output shaft locked in such position, the indicating hands or pointers 17-19 may be adjusted to a desired orientation which, in the case of a clock, must be a valid timekeeping position. Thereafter, when the respective output shafts are released through manipulation of the control shaft 44, each of the shafts will be rotated independently by its polarized magnet pair into its reset position, in which the respective shafts are in condition to be reengaged with the gear train by operation of the control shaft 44. In the case of a clock, it is desirable that the reset position of the hands17-19 be at a selected, nonprominent time of day or night, so that the clock can be reset to a predetermined start position, in accordance with a master clock signal at some time when the clock is least apt to be under observation. Thus, the reset time preferably is not on or particularly close to an even hour, half hour, or quarter hour.

It is of significance that the respective polarized magnet pairs be quite sharply polarized, so that the respective output shafts are drawn with considerable accuracy into their predetermined reset'positions and, in addition, so that the range of rotational orientation in which the magnet pairs are on dead center positions (oriented approximately 180 out of reset position but without sufficient effective torque to initiate thereset movement) is minimizedr, To this end, and as a specific feature of the invention, it is. advantageous to employ magnets of generally rectangular effective configuration, having poles or flux concentrators disposed at right angles to a polar axis extending diametrically through the shaft. This configuration, illustrated particularly in FIG. 5,provides for especially sharp alignment of the flux concentrators of the, magnets of a cooperative pair, since a slight rotary displacement or misalignment of the flux concentrators will'cause the concentrator elements to be offset in a generally linear direction and 'also to be disposed at an angle, resulting in a highly effective restoring force being exerted uponthe shaft to return it to its reset position. Thus, by way of example only, in a practical embodiment of the invention utilizing generally linear fiux concentrators of about /2 inch in length, disposed at right angles to the polar axis, at a distance of about /2 inch from the center of the shaft,- the-resetting accuracy of the polarized magnets is reliably within a fraction of a degree, such that proper alignment of the various gears after reset is reliably assured. Moreover, the range of dead center positions is so minute as to preclude, at least in a clock mechanism, the possibility of the output shafts failing to be reset with complete reliability. In this respect, the inherent nature of aclock mechanism is such that there can be no position in which all three of the resetting magnetpairs are in dead'center positions. Thus, under all circumstances, at least one of the output shafts inherently will start toward its reset posiiton when the shafts are disengaged from the reduction gear train. And, even though one of the other shafts occasionally (statistically, rarely) may be in a dead center condition at the start of reset, the minute vibrational motions involved in the resetting of the other shafts have been shown to be sufficient to displace a shaft from its dead center condition and assure its reliable return to reset position.

Referring specifically to FIG. 5, the polarized magnet 51a is shown in detail, it being understood that the illustrated magnet is representative of the others. Advantageously, the magnet includes a pair of pole pieces or flux concentrators 54, 55 of generally L-shaped cross section, which are secured to one face of the drive gear 26, in such manner that outer legs of the L project axially outward from the fiat face of the gear. In accordance with the invention, the projecting legs of the pole pieces are disposed symmetrically and at right angles to a predetermined polar axis extending diametrically (vertically in FIG. 5) through the central axis of the output shafts. A flat section 56, advantageously of a ferritic magnetic material such as Plastiform (a powdered ferrite in plastic matrix) is received in the channel-like recess formed by the oppositely disposed pole pieces 54, 55, advantageously such that the pole pieces extend axially slightly beyond the magnetic element 56, as indicated in FIG. 1. The opposite ends of the magnetic element 56 are magnetized in a front-t-o-back direction and reversely at the opposite ends. Thus, for example, the pole piece 54, lying against a south side of the magnetic element, will be strongly polarized as a south pole, while the pole piece 55, lying against a nort side of the magnetic element, will be strongly polarized as a north pole. The cooperating magnet 51b (not shown in FIG. 5) will, of course, be reversely magnetized, so that its north pole piece cooperates with the south pole piece 54 of the magnet 51a, when the shafts are in reset positions.

While other specific forms of reset magnet configurations may be employed, the above-described arrangement has been found to be particularly advantageous for the purpose intended, in view of its economical construction, flat configuration, and sharply polarized attraction. Of course, it may not be necessary, insofar as broader aspects of the invention are concerned, to provide for reset by magnetic means; where appropriate, suitable spring, gravity, or other reset arrangements may be provided.

In accordance with another aspect of the invention, a novel and highly effective arrangement is provided for actuating the control shaft 44 between its retracted and operative positions. To this end, a gear segment 60 is secured to the control shaft 44 and is arranged for cooperation with the gear 39, which is driven directly from the motor pinion 37. The gear segment 60 is provided with gear teeth extending over somewhat less than 180 of its circumference and is arranged for rotation about an axis concentric with the journal pins 45 of the control shaft.

The rotational orientation of the gear segment 60 with respect to the control shaft 44 is such that, when the control shaft 44 is in its operative position, maintaining the reduction train and all gears in meshing engagement, the gear teeth of the segment are out of mesh with the teeth of the drive gear 39. T 0 this end, the gear segment 60 advantageously is acted upon by an overcentering magnetic detent such that, when the control shaft 44 is in its operative position, the teeth of the gear segment lie just out of mesh with the drive gear 39, with the segment being urged by the magnetic detent in a direction to rotate the segment even further out of mesh. The segment is held in the desired operating position, however, by means of a stop lug 61, which is engaged by a stop arm 62 attached to the clapper arm 63 of a control solenoid 64.

The, magnetic detent arrangement consists of a first polarized magnetic element 65 secured to the back face of the gear segment 60 and a second and cooperating polarized magnetic element 66 secured to the front face of the frame plate 12 in directly opposing relation to the magnetic element 65. The movable magnetic element 65 is polarized north and south along a diameter, as indiand fixed to the respective output shafts, the hands will be positioned in valid timekeeping positions, when the output shafts are rotated independently to their respective reset positions.

When the gear reduction train is re-engaged after reset, it is necessary to retain the necessary mutual relationship between the output shafts -22 while effecting remeshing of the previously disengaged gears. Accordingly, as one of the features of the invention, special provisions are made, particularly in conjunction with the gear reduction interconnection between the second hand shaft and the minute hand shaft, and between the minute hand shaft and the hour hand shaft, for effecting remesh of the gear reduction systems in the desired synchronization. To this end, the gear and pinion combinations 30, 32 are provided with gears a, 33 of large effective tooth depth and with pinions 31, 34 of smaller effective tooth depth. Likewise, the reduction pinions 28, 29, meshing with the gears 30a, 33 respectively, are of large effective tooth depth, while the drive gears 26, 27, meshing with the pinions 31, 34, are of smaller effective tooth depth. Thus, the gear sets of smaller effective tooth depth, which adv'antageou'sly are of fine pitch, stub-tooth form, are arranged to have a depth of mesh less than the displacement or throw of the reset control shaft 44, so as to be drawn completely out of mesh when the control shaft is displaced from its closest or operating position to its retracted or reset position, with respect to the common axis of the output shafts. On the other hand, the gear sets of larger effective depth are provided with teeth of coarse pitch, long-tooth form and are arranged to have an overlap or depth of mesh somewhat greater than the total displacement of the control shaft 44, so that the latter gear sets are maintained in meshing engagement in all rotational positions of the control shaft 44.

Thus, with the above-described relationship between the cooperating gears of the reduction train, each of the gear and pinion reduction combinations 30, 32 is maintained in proper meshing relationship with its input gear (i.e., the reduction pinions 28, 29 carried by the second hand and minute hand shafts 20, 21, respectively). This, alone, is not enough, however, to assure that proper meshing of the reduction train takes place when the gears subsequently are re-engaged by rotation of the eccentric control shaft 44. Thus, in the case of the reduction combination 30, the input pinion 28 therefor and the output gear 26 therefor will occupy definite, predetermined rotary positions following a resetting operation; however, assuming a typical 8:1 gear reduction ratio between the pinion 28 and the gear 30a, the gear 30a may occupy any one of eight different rotary positions when the pinion 28 is in its definite reset position. Accordingly, the pinion 31 of the reduction combination must be so designed that in any one of those eight positions the pinion 31 is in a definite rotary alignment, as regards the teeth of the gear 26. In the illustrated example of an 8:1 gear ratio between the pinion 28 and gear 30a, the desired rotary orientation of the pinion 31 can be achieved by forming the pinion 31 with eight teeth, or any other number of teeth divisible by the number 8. Stated more broadly, the number of teeth on the pinion of the reduction combination must be an even multiple of the previous gear reduction ratio, assuming that only one pinion and gear reduction combination is employed between the connected output shafts. In the principle as thus stated, the term even multiple is intended to include the number l as a possible multiplier, as will be understood.

In a typical, practical embodiment of the invention, an overall gear reduction between the second hand shaft 20 and the minute hand shaft 21 of 60:1 is achieved advanta'geously by providing an 8:1 reduction ratio between the pinion 28 and the gear 30a and a 7.5 :1 reduction ratio between the pinion 31 and the gear 26, the pinion 31 being provided with sixteen teeth or a multiple of 2 times the preceding gear reduction ratio.

Following the principles set forth above, an overall 6 gear reduction ratio between the minute hand shaft 21 and the hour hand shaft 22 of 1251 is achieved by providing a 3 :1 reduction ratio between the reduction pinion 29 and the gear 33, and a 4:1 reduction ratio between the pinion 34 and the drive gear 27. Since the first-mentioned reduction ratio is 3:1, providing the gear and pinion reduction combination 32 with three possible rotary orientations when the minute hand shaft 21 is in its definite reset position, the number of teeth provided on the pinion 34 is a multiple of 3, thirty teeth being provided in a typical embodiment.

In the illustrated form of the invention, the principles mentioned above, for providing positive and accurate meshing alignment between reduction stages are not necessarily followed with respect to the meshing of the pinion 43 with the drive gear 25, since it is unnecessary to main tain a definite, geared-together rotary orientation between the second hand shaft 20 and any of the drive elements of the input train therefor. However, it will be apparent that such definite meshing orientations could be provided by an extension of the before-mentioned principles, at least when utilizing as a drive motor a synchronous inductor motor of the type described in the before-mentioned Riggs Patent No. 3,014,141 which, through residual magnetic effects, has a plurality of definite stopping posi-' tions. Thus, a typical motor has twelve distinct stopping positions, enabling the teeth of the drive pinion 37 to be aligned in a known relationship, if the number of teeth in the pinion is an even multiple of 12. However, since it is unnecessary, in the illustrated mechanism at least, to provide for a definite meshing orientation between the pinion 43 and drive gear 25, the additional expense of making such provisionsmay be avoided. In this respect, the fact that the motor 12 stops in any one of twelve distinct positions, rather than a single, definite reset position, coupled with the fact that the overall gear reduction ratio between the motor shaft 36 and the second hand 20 is 250:1, introduces unusually high multiples into the before-mentioned formulas for determining the proper number of gear teeth in the reduction stages. Thus, it is expeditious and practical, at least in a clock mechanism, to omit providing for a definite meshing orientation between the pinion 43' and the drive gear 25 at the end of reset, particularly since no difficulty is experienced in bringing an already rotating pinion 43 into driving mesh with the gear 25 when the control shaft 44 is operated to engage the gear train.

Advantageously, the gear and pinion reduction combination 41, forming part of the reduction train driving the second hand drive gear 25, is so constructed that the gear 42 and its driving pinion 40 are provided with teeth of coarse pitch, long-tooth form and are arranged to have an overlap somewhat greater than the total displacement of the control shaft 44. At the same time, the pinion 43 and the drive gear 25 are provided with teeth of fine pitch, stub-tooth form, arranged to have a depth of mesh less than the displacement of the control shaft, so as to be drawn completely out of mesh when the control shaft isrotated to a retracted position, permitting free rotation of the second hand shaft 20 to its predetermined reset position.

In accordance with one of the specific features of the invention, novel and particularly advantageous arrangements are provided for independently returning each of the output shafts 20-22 to their respective reset positions, when the output shafts are released by disengagement of their respective drive gears 25-27. To this end, each of the output shafts carries a polarized magnet 50a52a. Advantageously, the magnets 51a, 52a are mounted on the respective drive gears 26, 27 for the minute hand and hour hand shafts 21, 22, while the magnet 50a is secured to a disk 53 fixed to the end of the second hand shaft 20. Each of the polarized, rotating magnetsSOa-SZa cooperates with a similarly polarized but fixed magnet 50b 52b, substantially as indicated in FIG. 1. The fixed magcated by the N and S designations shown in broken lines in FIG. 3. Likewise, the fixed magnetic element 66 is polarized north and south along a diameter, as indicated by the N and S designations shown in full lines in FIG. 3. The relative orientation of the axes of polarization of the magnetic elements 65, 66 are such that, as shown in FIG. 3, when the stop lug 61 is seated against the stop arm 62, the north pole of the movable magnet 65 is adjacent the north pole of the fixed magnet 66, but is slightly offset therefrom in a direction such that the repelling forces of the like magnetic poles tend to seat the stop lug 61 firmly against the stop arm 62. Similarly, the south poles of the magnetic elements exert repelling forces tending to seat the stop lug 61. Accordingly, when the mechanism is conditioned as shown in FIG. 3 the gear segment 60 is effectively held in a fixed position,with its gear teeth just out of mesh with the drive gear 39 in the direction in which the segment is urged by the repelling magnetic forces.

Advantageously, the energizing circuit forthe solenoid 64 is connected in parallel with the energizing circuit for the main drive motor 35, and both the solenoid and drive motor are connected to the power source through an appropriate switching arrangement, indicated schematically at 67, under the control of a master timer 68. Accordingly, when the switch 67 is opened by the master timer, the energizing circuits for the solenoid 64 and drive motor 35 simultaneously are interrupted.

When the power circuit is interrupted, the motor 35, and

therefore the drive gear 39, immediately stop. At the 7 same time, the solenoid 64 is de-energized, releasing its clapper arm 63 and permitting its stop arm 62 to be retracted by a spring 69 (FIG. 2). This releases the gear segment 60 for rotation due to the combined repelling and attracting forces of the magnetic elements 65, 66. As will be understood, the magnetic elements 65, 66 will exert a rotating torque upon the gear segment 60, tending to bring the north pole of the gear segment into polar alignment with the south pole of the fixed magnetic element 66, and vice versa. This causes the gear segment 60 and the attached eccentric control shaft 44-to be rotated substantially through 180, whereby the pinions 43, 31, and 34 are retracted out of mesh with the respective drive gears 2527, the gears 42, 30a, and 33 remaining in at least partial mesh, however, due to their longer tooth form, as previously explained, The described relationships are evident in FIGS. 3 and 4. i In accordance with the invention, the arc over which the teeth of the gear segment 60 extend is such, in relation to the tooth form, gear diameter, etc., that rotation of the gear segment 60 through somewhat less than 180 '(e.g., about 160l65) will bring the gear segment from a position in which the trailing teeth of the segment are just out of mesh with the drive gear 39 into a position in which the leading tooth of the segment is abutting a tooth of the drive gear 39, at least substantially in meshing relationship. The arrangement is such that the leading tooth of the gear segment engages a tooth of the drive gear 39 in a rotational orientation of the gear segment in which the magnetic poles thereof have not yet been brought into alignment with the opposite poles of the fixed magnetic element 66. Thus, as shown in FIG. 4, when the first tooth of the gear segment engages a tooth of the drive gear 39, the gear segment 60 issubject to strongly attractive magnetic forces of the misaligned, unlike poles of the respective magnetic elements 65, 66, tending to rotate the gear segment in a direction which will carry the segment into meshing relationship with the drive gear 39. However, since the drive gear 39 is at that time stopped, the gear segment 60 will be held motionless, retaining the control shaft 44 in its retracted or reset position, in which all of the output shafts 20-22 are disengaged and permitted to return to a predetermined reset condition.

Subsequently, when the power source is reconnected to the motor 35 and solenoid 64, by action of the master timer 68 closing the switch 67', the motor 35 is energized to drive the gear 39 in a counterclockwise direction, as viewed in FIG. 4. The magnetically applied torque acting on the gear segment is sufiicient to insure positive meshing engagement of the segment 60 and drive gear 39, as the gear 39 starts to rotate, and the segment thereafter is driven positively by the gear 39 through an angle somewhat in excess of 180, until the poles of the movable magnetic element are driven into and beyond aligned relation with like poles of the fixed magnetic element 66. With continued rotation of the drive gear'39, the last tooth of the gear segment 60 ultimately passes out of mesh with the drive gear, at which time the gear segment 60 is acted upon essentially by the repelling influence of like magnetic poles of the elements 65, 66, so that the gear teeth are completely cleared. At this point, the stop lug 61 moves into engagement with the stop arm 62, which had been returned to its active or blocking position by energization of the control solenoid 64 simultaneously with that of the motor 35.

Advantageously, to assure uniformly reliable operation of the magnetic detent acting upon the gear segment 60 and to assure proper meshing of the gear segment and its drive gear 39 upon resumption of energization, following reset, arrangements are provided for reliably assuring that the drive gear 39 will have a substantially definite or fixed relationship to the gear segment 60 during a reset interval. To this end, specifically advantageous use is made of an inductor type synchronous motor of the type described in the before-mentioned Riggs Patent No. 3,014,141, which has definite stopping positions. Thus, in a typical practical embodiment of the invention, the motor 35 has twelve definite stopping positions in which it may come to rest upon de-energization. Thus, by providing the motor pinion 37 with a predetermined number of teeth, constituting an even multiple of the number 12, the motor pinion 37 always will come to rest with its teeth in a specific, predetermined orientation. Typically, but not necessarily, twelve teeth are used on the motor pinion 37, since this is the lowest number capable of use with a motor having twelve stopping positions.

One of the significant advantages to the control arrangement described, for manipulating the eccentric control shaft 44 in accordance with the energized and de-energized conditions of the mechanism, resides in the fact that the control solenoid 64 does not have to perform work upon the control shaft. This is of particular significance in clock applications, for example, where the size and cost of the solenoid 64 must. be maintained at a practical minimum and where inrush currents should be kept as low as possible. Thus, if the solenoid 64 were required to do work in closing, as by utilizing the solenoid to effect movement of the eccentric control shaft 44, not only would the solenoid have to be substantially larger and more costly, but significant amounts of energizing current would be required during the closing interval. With the mechanism of the invention, on the other hand, the control solenoid 64 operates only against a very light spring 69 and performs no work whatever upon the control shaft 44. Rather, it simply positions the stop arm 62 to intercept the stop lug 61, after the lug has passed through its magnetic overcenter position established by the orientation of the polarized magnetic elements 65, 66. All of the work required to drive the gear segment 60 to its overcentered, operative position is derived from the motor 35, which does not require a large inrush current to perform the necessary work and, moreover, is at that time disconnected from the load of the reduction train and output shafts.

T e mechanism of the invention is uniquely adapted for use as a slave clock unit which, at a predetermined time of day, is reset precisely in accordance with the operation of a master clock. The necessary resetting is effected by interrupting the energy supply to the motor 35 iii and control solenoid 64 for a'few seconds, sufiicient to effect the substantially instantaneous disconnection of the reduction gear train and rotation of the output shafts to their respective reset positions. At a predetermined reset time, corresponding to the reset indication of the slave unit, energization is restored to the control solenoid and drive motor, so that the slave unit resumes operation in exact synchronism with the master timekeeping control.

It should be understood, however, that the form of the invention herein specifically illustrated and described is intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

What is claimed is:

1. A resettable gear mechanism comprising (a) a first output shaft,

(b) a second output shaft,

(c) reduction gearing interconnecting said output shafts for output rotation at different but related rotational speeds,

(d) said reduction gearing including a coaxially mounted gear and pinion combination and also including a related pinion connected to one of said output shafts and a related gear connected to the other of said output shafts, the gear element of said combination being arranged for meshing engagement with said related pinion and the pinion element of said combination being arranged for meshing engagement with said related gear,

(e) reset shift means operable to a reset'condition to shift at least one of the elements of the gear and pinion combination relative to its related gear or pinion to a position in which said one element is out of mesh with its related gear or pinion while the other element of said combination remains in mesh with its related gear or pinion, and

(f) means operative to rotate said output shafts independently of said reduction gearing to predetermined reset positions while said reset shift means is in its reset condition,

(g) said one element being restored to meshing engagement with its related gear or pinion upon return of said reset shift means to an operating condition.

2. The resettable gear mechanism of claim 1, in which (a) the number of teeth on said one element of the gear and pinion combination is an even multiple of the number of possible rotary positions which may be assumed by the said one element when the output shaft connected to the related gear or pinion for the other of said elements is rotated to its predetermined reset position.

3. The resettable gear mechanism of claim 1, in which (a) said one element of the gear and pinion combination is the pinion element, and

(b) the number of teeth on said pinion element is an even multiple of the gear ratio between the ,gear element of said combination and its related pinion.

4. The resettable gear mechanism of claim 1, in which (a) said gear and pinion combination is mounted on a common shaft, and

(b) said reset shift means comprises said common shaft and means for shifting said common shaft in a radial direction toward and away from the related gear or pinion cooperating with said one element of the gear and pinion combination.

5. The resettable gear mechanism of claim 4, in which (a) said related gear and pinion are mounted for rotation on a common axis,

(b) the teeth of said one element of the gear and pinion combination are of less effective depth than the teeth of the other element of the combination, and

(c) said reset shift means is operable through a predetermined limited distance so related to the effective depth of the teeth of said gear and pinion elements that the teeth of said one element are shifted out of mesh while the teeth of the other element remain in mesh.

6. The resettable gear mechanism of claim 4, in which (a) journal means are provided for mounting said common shaft for rotation independently of said gear and pinion combination and about an axis offset from the axis of rotation of said combination,

(b) said reset shift means includes means for rotating said common shaft through a substantial angle.

7. The resettable gear mechanism of claim 6, in which (a) an input drive motor is controllably associated with one of said output shafts, and

(b) said means for rotating said common shaft comprises means controllably associated with said drive motor.

8. The resettable gear mechanism of claim 7, in which (a) a gear segment is mounted on said common shaft,

(b) a drive gear is connected to said motor and is engageable with the teeth of said gear segment when said gear segment is in predetermined rotary orientation,

(c) yieldable detent means operative when said motor is deenergized to urge said gear segment in its driven direction into initial meshing engagement with said drive gear, whereby said gear segment is driven upon energization of said motor,

(d) said yieldable detent means being further operative when said gear segment is driven through its predetermined range of meshing engagement to urge the segment in its driven direction, toward meshing engagement with said drive gear,

(e) stop means are provided to engage said gear segment for limiting its rotation in the driven direction under the urging of said detent means, and

(f) solenoid control means are associated with the energizing circuit for said motor for shifting. said stop means to operative position, when said motor is energized, and to inoperative position when said motor is deenergized.

9. The resettable gear mechanism of claim 8, in which said yieldable detent means comprises (a) a first polarized magnet mounted in fixed relation adjacent said common shaft and having its polar axis intersecting the axis of rotation of said shaft, and

(b) a second polarized magnet carried by said common shaft and cooperatively aligned and related to said first magnet whereby, in any rotary position of said common shaft, said second magnet and said common shaft are urged toward a position of predetermined rotary alignment.

10. A resettable clock, comprising (a) a plurality of concentrically journalled time indicating output shafts, including a low speed shaft and one or more higher speed shafts,

(b) a drive gear fixed to each of saidoutput shafts,

(c) a reduction pinion fixed to the drive gear for each of the higher speed shafts,

(d) a transmission shaft mounted in parallel relation to the common axis of said output shafts,

(e) a gear and pinion reduction combination connecting the reduction pinion of each higher speed shaft to the drive gear for the shaft of the next lower speed,

(f) each of said gear and pinion combinations being mounted for rotation on said transmission shaft,

(g) the pinions of each reduction combination having teeth of less effective depth than the teeth of the gears of such combinations,

(h) reset shift means operable for controllably moving said transmission shaft away from said common axis a distance sufficient to disengage the pinions of said reduction'combinations from the drive gears for the respective lower speed shafts but insufficient to 13 disengage the gears of said reduction combinations from the pinions of the respective higher speed shafts, and

(i) rrieans aetin'g individually on said output shafts when said reset shift means is operated to urge the output shafts disenga ed thereby to predetermined rotary positions.

111' The resettable clock of claim 10, in which (a) the said predetermined positions to which the respective' disengaged shaftsare urged are mutually consisteiit with gear reduction relationships provided by said pinions and gears for timekeeping opera- I tion, and

(b) each pinion of each of said gearand pinion combinations has a predetermined number of gear teeth, which number is an event multiple of the reduction ratio between the gear of the same combination and the pinion of the next higher speed shaft.

12; In resettable apparatus; I

(a) an output shaft and a transmission shaft in spaced parallel relationship with each other,

(b) reduction gearing including first .gear means mounted on said output shaft and second gear means mounted on said transmission shaft for interconnecting the same,

(a) reset shift means for movingrsaid transmission shaft away from said .output shaft a distance sulficient to disengage at least portions of said reduction gearing,

(d) an electric drive motor for supplying driving power to said output shaft, and

(e) means for interconnecting said drive motor and the reset shift means for said transmission shaft whereby, upon energization of said motor, said transmission shaft is shiftedto a position in which said reduction gearing maintains said shafts in interconnected relation and, upon deenergization of said motor, said transmission shaft is shiftedto a position in which the said portions of said reduction gearing are disengaged, 4 I

(f) at least one of the shifting movements of said transmission shaft being effected by the power of said motor. r

13. The resettable apparatus of claim 12 which comprises I I (a) a movable polarized magnet carried by said output shaft, and I I I (b) a stationary polarized magnet mounted in close axial proximity to the movablemagnet, whereby con- I stantlyto urge the movable magnet and the output II shaft fixed thereto to a predetermined rotary position. II 14, The resettable apparatus of claim 13, in which each of saidpolarized magnets comprises I I I I (a) spaced opposed magnetic poles disposed in prede- I .termined radially spaced relation to the axis of rotation of said output shaft, I

(b) said poles being symmetrically arranged with respect to ,said axis of rotation and being of linear configuration and disposed along lines substantially at right angles to a polar axis extending through said I axis of rotation. I

15, A resettable clock comprisin I I (a) a plurality of time indicating output shafts, in-

eluding a low speed shaft and one or more shafts of successively higher speeds, I

(M a drive gear associatedwith each of said shafts for imparting rotary drivingmotion thereto,.

(c) a reduction, pinion associated with each of the higher speed shafts, I

(d) an input drive including an electric motor for .said clock, I I II I (e) connectinggear means for operatively connecting the drive gears of the lower speed shafts each to the reduction pinion of the shaft of the next higher speed and for operatively connecting the drive gear of the highest speed shaft to said input drive,

(f) reset shift means including a solenoid operative when deenergized to .controll-ab ly disengage said connecting gear means from said drive gears while maintaining engagement between said connecting gear means and said reduction pinions and said input drive, said solenoid being operative when energized to. cause engagement of said connecting gear means with said drive gears, I I I (g) reset means acting on the respective shafts when said connecting gear means are so disengaged to rotate said shafts separately to predetermined positions, and

(h) means for energizing said motor and said solenoid from a common source of energizing power, whereby said motor and said solenoid are energized and deenergized substantially simultaneously.

16. The resettable clock of claim 15, in which I (a) said reset shift means includes means driven by said motor, whereby the effective work input to said reset shift means is substantially isolated from said solenoid.

17. A resettable clock, comprising (a) a plurality of concentrically journalled time indicating output shafts, including a low speed shaft and one or more higher speed shafts,

(b) a drive gear fixed to each of said output shafts,

(c) a reduction pinion fixed to the drive gear for each of the higher speed shafts, I

(d) a transmission shaft mounted in parallel relation to the common axis of said output shafts;

(e) a gear and pinion reduction combination connecting the reduction pinion of each higher speed shaft to the drive gear for the shaft of the next lower speed, I

(f) each of said gear and pinion combinations being mounted for rotation on said transmissionshaft,

(g) the pinions of each reduction combination having teeth of less effective depth than the teeth of the gears of such combinations,

(h) reset shift means operable for controllably moving said transmission shaft away from said common axis a distance sufficient to disengage the pinions of said reduction combinations from the drive gears for the respective lower speed shafts but insufficient to disengage the gears of said reduction combinations fromthe pinions of the respective higher speed shafts,

(i) means acting individually onsaid output shafts when said reset shift means is operated to urge the output shaftsdisengaged thereby to predetermined rotary positions, I

(j) an electric drive motor for supplying driving power to the highest speed output shaft, and I (k) means for interconnecting said drive motor and the reset shift means for said transmission shaft whereby, upon energization of said motor, said transmission shaft is shifted to a position engaging the output shafts in interconnected relation and, upon deenergization of said motor, said transmission shaft is shifted to a position disengaging the outpu-tshafts, I I II I I (l) at least one of the shiftingmovements of said transmission shaft being effected by the power of .said motor. I I

18. A resettable clock, comprising I Y (a) a plurality of concentrically journalled time indicating output shafts, including a low speed shaft and one or more higher speed shafts,

(b) a drive gear fixed to each of said output shafts,

(c) a reduction pinion fixed to the drive gear for each of the higher speed shafts,

(d) a transmission shaft mounted in parallel relation to the common axis of said output shafts,

(e) a gear and pinion reduction combination connecting the reduction pinion of each higher speed shaft to the drive gear for the shaft of the next lower speed,

(f) each of said gear and pinion combinations being mounted for rotation on said transmission shaft,

(g) the pinions of each reduction combination having teeth of less effective depth than the teeth of the gears of such combinations,

(h) reset shift means operable for controllably moving said transmission shaft away from said common axis a distance sufficient to disengage the pinions of said reduction combinations from the drive gears for the respective lower speed shafts but insufficient to disengage the gears of said reduction combinations from the pinions of the respective higher speed shafts,

(i) means acting individually on said output shafts when said reset shift means is operated to urge the output shafts disengaged thereby to predetermined rotary positions,

(j) an electric drive motor for supplying driving power to the highest speed output shaft,

(k) means for interconnecting said shaft motor and the reset shift means for said transmission shaft whereby, upon energization of said motor, said transmission shaft is shifted to a position engaging the output shafts in interconnected relation and, upon deenergization of said motor, said transmission shaft is shifted to a position disengaging the output shafts,

(l) at least one of the shifting movements of said transmission shaft being effected by the power of said motor,

(In) said reset shift means including a shift element adapted to be driven in a cyclical manner by said drive motor,

(n) yieldable overcentering means acting on said shift element to urge said element from any position in its cyclical path to a predetermined position, and

(o) controllable solenoid actuated stop means operable to restrain said shift element in a fixed operative position displaced from said predetermined position,

(p) said stop means being retractable when said motor is deenergized to accommodate movement of said shift element by said overcentering means into driving relationship with said motor,

(q) said motor and said shift element being so related that, upon energization of said motor, said shift element is driven through more than one half of its cycle and through a'predetermined overcentering position, 7

(r) said shift element automatically being moved out of driving relationship with said motor upon said shift element being driven through said overcentering position,

19. A resettable' clock, comprising (a) a plurality of concentrically journalled time indicating output shafts, including a low speed shaft and one or more higher speed shafts,

.(b) first and second drive gears respectively 'afiixed to said output shafts,

(c) a reduction pinion fixed to the drive gear for each of the higher speed shafts, (d) a transmission shaft mounted in parallel relation to the common axis of said output shafts,

(e) a gear and pinion reduction combination connecting the reduction pinion of each higher speed shaft to the drive gear for the shaft of the next lower speed,

(f) each of said gear and pinion combinations being respective lower speed shafts but insufiicient to disengage the gears of said reduction combinations from the pinions of the respective higher speed shafts,

(i) means acting individually on said output shafts when said reset shift means is operated to urge the output shafts disengaged thereby to predetermined rotary positions,

(3') an electric drive motor for supplying driving power to the highest speed output shaft,

(k) means including a third drive gear for interconnecting said drive motor and the reset shift means for said transmission shaft whereby, upon energization of said motor, said transmission shaft is shifted to a position engaging the output shafts in interconnected relation and, upon deenergization of said motor, said transmission shaft is shifted to a position disengaging the output shafts.

(l) at least one 'of the shifting movements of said transmission shaft being effected by the power of said motor,

(rn) said reset shift means including a gear segment adapted to be driven in a cyclical manner by said third drive gear,

(n) yieldable overcentering means acting on said gear segment to urge :said segment from any position in its cyclical path to a predetermined position, and

(o) controllable solenoid actuated stop means operable to restrain said gear segment in a fixed operative position displaced from said predetermined position,

(|p) said stop means being retractable when said motor is deenergized to accommodate movement of said gear segment by said overcentering means into driving engagement with said third drive gear,

(q) said gear segment and said third drive gear being so related that, upon ener-gization of said motor, said gear segment is driven by said third drive gear through in excess of degrees of rotation of said gear seg- 1116121? and through a predetermined overcentering position, i

(r) said gear segment and said third drive gear automatically being disengaged upon said gear segment being driven through said overcentering position.

20. A resettable clock comprising i (a) a' plurality of time indicating output shafts, in-

cluding a low speed shaft and one or more shafts of successively higher speeds,

(b) a drive gear associated with each of said shafts for imparting rotary driving motion thereto,

(c) a reduction pinion associated with each of the higher speed shafts,

(d) an input drive for said clock, 7

(e) connecting gear means for operatively connecting the drive gears of the lower speed shafts each tothe reduction pinion of the shaft of the next higher speed and for operatively connecting the drive gear of the highest speed shaft to said input drive,

(f) reset shift means for controllably disengaging said connecting gear means from said drive gears while maintaining engagement between said connecting gear means and said reduction pinions and said input drive, and

(g) reset means acting on the respective shafts when said connecting gear means are so disengaged to rotate said shafts separately to predetermined positions,

(h) said reset means including, a movable polarized magnet carried by each of said output shafts and a stationary polarized magnet for each of said movable magnets mounted in close axial proximity thereto, whereby constantly to urge the movable magnet'and the output shaft fixed thereto to a predetermined rotary position, v (i) each of said movable and stationarypolarized magnets having an elongated pole piece of generally L- shaped cross-section disposed ,with one leg of the L in a plane normal to the corresponding output shaft (j) a cooperating pair of said movable and stationary 1 7 polarized magnets comprising a pair of axially spaced L-shaped pole pieces arranged with their respective other legs projecting toward each other and arranged to be brought into aligned, facing relationship.

21. In resettable apparatus,

(a) an output shaft and a transmission shaft in spaced parallel relationship With each other,

(b) reduction gearing including first gear means mounted on said output shaft and second gear means mounted on said transmission shaft for interconnecting the same,

(c) reset shaft means for moving said transmission shaft in a radial direction away from said output shaft a distance sufficient to disengage particular portions of said reduction gearing but insufiicient to disengage other portions of said reduction gearing,

(d) an electric drive motor for supplying driving power to said output shaft, and

(e) means for interconnecting said drive motor and the reset shift means for said transmission shaft whereby, upon energization of said motor, said transmission shaft is shifted to a position in which said 20 LEO SMILOW, Primary Examiner.

LEYLAND M. MARTIN, Examiner.

reduction gearing maintains said shafts in interconnect'ed relation and, upon deenergization of said motor, said transmission shaft is shifted to a position in which said particular portions of said reduction gearing are disengaged while said other portions remain in engagement,

(f) at least one of the shifting movements of said transmission shaft being effected by the power of said motor.

References Cited by the Examiner UNITED STATES PATENTS 1,957,543 5/1934 Kenerson 58-26 X 3,090,191 5/ 1963 Montgomery 58-34 3,112,069 11/ 1963 Truesdell et a1. 235-144 FOREIGN PATENTS 1,282,670 12/ 1961 France.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1957543 *Dec 12, 1931May 8, 1934Standard Electric Time CompanyElectric clock
US3090191 *Sep 29, 1960May 21, 1963Montgomery Mfg Company IncSecondary clock setting means
US3112069 *Feb 28, 1961Nov 26, 1963Gen ElectricResetting mechanism for rotatable shafts
FR1282670A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3693344 *Dec 22, 1970Sep 26, 1972Omega Brandt & Freres Sa LouisTimepiece movement
US3695035 *Sep 22, 1970Oct 3, 1972Omega Brandt & Freres Sa LouisTimepiece movement
US3731481 *Mar 24, 1972May 8, 1973Citizen Watch Co LtdTime-setting device for electric timepiece
US3732685 *Apr 3, 1972May 15, 1973Tri TechClock mechanism
US3897700 *Jun 18, 1974Aug 5, 1975Tri TechClock setting mechanism
US7348742Jul 21, 2005Mar 25, 2008Energy Focus, Inc.Lighting fixture with synchronizable optical filter wheel and related method
US20060109653 *Jul 21, 2005May 25, 2006Takacs Laszlo ALighting fixture with synchronizable optical filter wheel and related method
Classifications
U.S. Classification368/60, 968/506, 235/144.00R, 116/301, 368/185
International ClassificationG04C11/00
Cooperative ClassificationG04C11/00
European ClassificationG04C11/00