US1872377A - Electric clock - Google Patents

Description

ELECTRIC CLOCK Filed May 10, 1930 3 Sheets-Sheet 1 "m i ffjfjfjjjj fmfenm Aug. 16, 1932. R. H. WILMETH ELECTRIC CLOCK Filed May 10. 1930 3 Sheets-Sheet 2 Patented Aug. 16, 1932 i UNITED STATES PATENT OFFICE noscon n. WILMETH, or srnmermtn, ILLINOIS, Assicmon TO SANGAMO ELECTRIC COMPANY, or SPRINGFIELD, rumors, A CORPORATION or rumors spring of the clock to act on ELECTRIC cLocx Application filed May 10, 1930. serial No. 451,216.

The present invention relates to electric clocks, and particularly tov striking, clocks adapted to strike at certain time periods, such as on the hour, half hour, etc. i

Electric-clocks are now generally provid ed with an electrically operated means for operating the] striking mechanism. This provision usually consists of the employment of an electric motorin addition to the conventional winding motor, which is cont-inuously connected across the current supply line. While this arrangement has an advantage in that the operation of the striking mechanism in no way affects the timing characteristics of the clock, there are nevertheless severalmajor objections thereto. It will be apparent that in such-a construction, it the current supply fails prior to a striking period, the strikingmechanism mustnecessarily remain silent. must necessarily be employed in such an arrangement, thus materially increasing the manufacturing costs of this type of striking clock. 1 t t i The present invention contemplates the em ployment of the winding motor to operate the striking mechanism during a striking pe- 'riod, at the same time permitting the main the striking mechanism toa slight degree. Thus,'should the current supply fail during a striking period, provision is made for. carrying over of the operation of thestriking mechanism by the main spring. These functionsare accomplished by the interposition of a difler ential gear in the series of reduction gears between the main spring and the winding motor. This differential gear is adapted to transmit power from the winding motor to g the striking mechanism during a striking ffperiod without producing any winding e ect on the main spring,which during a striking period is adapted to unwind. somewhat in spite of the operation of the winding motor. Thus, during a striking period, all the energy transmitted to the clock mechanism by the winding motor is absorbed by the striking mechanism. This is accomplished byjso a'rranging the reduction gears that the maxirate at whichthe motor can windthe mum Furthermore, two motors main spring is always somewhat lessthan the rate of-unwinding of the main spring during the striking operation, with the result that with the power either on or oil', the main spring is unwinding slightly during a striking period.

With the. above in view, the main object of this invention is to provide a striking clock wherein the operating energy for the time keeping mechanism and for the striking mechanism is derived electrically, as from the ordinary house lighting circuit.

Another object is .to provide a striking mechanism operable by a winding motor for the main spring or" by the main spring. A further object is the provision of a novel gear'connection between the winding motor and the main spring so that the main spring at all times acts to limit the amount of energy delivered by the motor to the strikin mechanism.

Anotlier object is, the provision of a novel gear connection between the winding'motor and the main springso that all the energy delivered by the winding motor is taken up by the striking mechanism during a striking period." k p A further object is to provide such a gear arrangement that. the striking mechanism the winding motoris operating. 1

A further object is the provision of a novel gear arrangement whereby'the maximumspeed at which the motor canwind the main spring is always somewhat less'than the rate or unwinding of the main spring during a striking operation.

Another object is to providea novel striking means whereby clearly distinguishable audible signals are emitted at predetermined time periods such, for example, as hourly ,3

and half-hourly periods by the operationof a single operating mechanism. This is accomplished. by the provision of two coacting striking hammer arms having a lost motion provision therebetween whereby both arms may be actuated in unison or one of them without the other. Thus at the hour interval, two gongs are struck while on the halfhour only one is strucl In conjunction with this port-ion of the mechanism, a control means has been provided for rendering one of the arms ineffective at the half-hour pcriod.

Other and further objects will appear from the following detailed description of an embodiment of my invention illustrated the accompanying drawings in which;

Figure l is a fragmentary elevational view of a clock, portions thereof being broken away to illustrate the striking mechanism control elements Figure 2 is elevationa-l section of the clock frame behind the front frame plate, and showing the r duction gears from the winding motor to the main spring;

Figure 3' is a section similar to i M, taken along a plane closer to the rear frame plate and. illustrating the striking mechanism;

Figure is a transverse section of the clock mechanism taken along the line 4-4 of Figure 2;

Figure 5 is transverse section of the striking mechanism taken along the line 55 Figure 3 and showing the differential gear section;

Figure 6 is a detailed view of the differential gear; and

liigure is an enlarged perspective detail of the hammer arm mounts illustrating the lost motion provision therebetween.

The operating parts of the clock may be enclosed in a. housing of any preferred design, with striker gongs 11 and 12 disposed either to one side of or below the clock mech anism proper; The clock movement is assembled between the front and rea frame plates13 and 14, which are held in spaced relation by intermediate spacing posts 15. An electric motor mechanism 16 for winding the clock movement and for operating the striker mechanism is preferably mounted on the rear side of the rear frame plate 14. This motor maybe of any type or construction capable of remaining in a stalled position over indefinite time periods, and is directly connected across the line. Preferably, this motor is an alternating current induction motor of the general construction disclosed. in the copending application of Frederick C. Holtz, Serial No. 750,201, filed November 15, 1924.

I shall first describe the driving train of the clock to illustrate its correlation with the striking mechanism and the winding operation. In the exemplary construct-ion shown, the armature shaft 21 of the clock motor 16 extends through the rear plate 14 of the frame and carries a pinion 22 which meshes with a spur gear 23 on an arbor 24.

It will be understood that the gear train which I am about to describe is disposed between the spaced frame plates 13 and 14 and that the several arbors to which reference shall be made are journalled at their front and rear ends. in. these plates, respectively. Mounted on the arbor :24 isa pinion 25 which meshes with a large gear 26 on a second arbor 27. This latter arbor carries a pinion 28 which. meshes with a large gear 29 on a third arbor 31 towhich a pinion; 32. is secured. The latter pinion 32 meshes with a bull gear of aspur-gear differential, enerally indicated at 34.

Referring particularly to Figure 5, the differential 34 comprises the bull gear- 33 which carries thereon two diametrically disposed differential pinions 36 rotatably mounted on shafts 37 which have their end portions cut away to form flat, diametric surfaces 38. The shafts 37 are seated in recesses 39 with the fiat end surfaces in align ment with the rear surface of the bull gear 33, and are retained in fixed position thereon by bolts 41, theundersides of the heads of which engage the fiat end surfaces of the shaft 37- Each of the differential pinions 36 has bearing portions 42 which extend beyond either of their faces and occupy the entire space between the gear periphery and the web portions 33 thereof, with the toothed peripheries closer to the periphery of the bull gear 33 than to the hub thereof. A shaft 43 carries the bull gear 33, which is rotatably mounted thereon.

Between. the front frame plate 13 and the front end of the hub of the bull gear, a spur gear 44 having a forwardly extending hub portion 45, is rotatably mounted on the shaft 43, the forward end of the hub 45 bearing on the rear of the front frame plate 13, and the rear face of the gear 44 at the hub hearing on the forward end of the hub of the bull gear. The teeth of the spur gear 44 are meshed with both differential pinions 36. Secured fixedly to the hub portion 45 of the gear 44 and forwardly of this gear, is a smaller spur gear 46. Rotatably mounted on the shaft 43 between the rear plate 14 and hub 34 of the bull gear, is a spur gear 47. having a rearwardly extending hub portion 48. the rear end of which bears on the front face of the rear frame plate 14 while the front face of the gear 47, at the hub bears on the rear end of the hub of the bull gear 33. The difierential pinions 36 mesh with the gear 47. The rearwardly extending hub portion 48 of the gear 47 carries thereon. and fixedly secured thereto, a larger spur gear 49, having a series of rearwa-rdly extending circumferentially spaced pins 51. The purpose of these pins will be hereinafter described.

Referring now to Figures 2 and 4, the gear 46 meshes with a gear 52 on an arbor 53,'

the gear 52 in turn meshing with a gear 54 on an arbor 55 which carries themainsprmg end of the main. spring at 58. of the main spring is suitably connected with the main spring barrel 57, the cover 59 of which extends radially beyond the edge thereof and is formed with circumferential gear teeth 61. p

A collar 62 suitably splined or otherwise connected to, the arbor 55 in any suitable.

manner for rotary movement therewith and sliding movement therealong, has a threaded rear portion 63 which en ages internalthreads in a boss 64 extending forwardlyv from the cover 59. The collar 62 has at its forward end a radially extending flange 65, the rear face of which bears against a fork 66 of a brake supporting lever 67 pivoted to a supporting post 68 secured to the forward frame plate 13, at 69. The brake supporting lever 67 is normally spring projected forwardly by a flat spring 71 suitably secured thereto at 72 with its free end abutting the rear end of the post 68. A brak'e 73 is adjustably secured to the lever 67 at- 7 4 and carries thereon a brake shoe 75 which is adapted to engage the forward face of the gear 23 as the main spring approaches its.

fully wound condition to brake the operation of the winding motor 16 and to stop the latterwhen the main spring is in fully wound condition. i j c A pinion7 6 on a cannon pinion arbor 77 meshes with the gear on the main" spring cover plate 59 and transmits motion to-the arbor 77 to which, near the forward end thereof and behind the front frame plate 13, a gear 78 is secured. The latter gear meshes with a pinion 79 onan arbor 81 to. which a gear 82 is also secured and which transmits rotary movement to a pinion (not shown) on an arbor 83. The latter arbor hassecured thereon a gear 84 which meshes with apinion 85 of an escapement mechanism 86; The mechanism thus far described completes the train of gearingleading from the winding motor to the main spring and to the escapement mechanism.

Referring now particularly to Figures 3 and 5, the gearing arrangement for the strik-v ing mechanism comprises a pinion 91 on an arbor 92 which meshes with the gear 49'of the differential 34. A large gear 93 fixed to the arbor 92 meshes with a'pinion 94 on an arbor 95 which carries a gear 96 meshing with a pinion 97 on an arbor 98. The latter arbor carries thereon a vane type, air beat-er governor 99. The arbor 95 carries thereon and secured thereto, a stop arm 101 adjacent the gear 96'and which is adapted to rotate 7 in a, plane between the gear 93 and the forward edge of the governor 99, so that it is positioned proximately to the forward frame plate 13. The gear 93 is provided with a forwardly projecting pin 102 near its periphery and which projects into a circular groove103 provided on the rear side of the ront frame plate 13. The free end of pin 102 is spaced from the side and bottom walls of the groove 103 and its path is circular about the arbor 92. Thelatter arbor has secured thereto on its forward end, which projectsthrough the front frame plate 13, a cylindrical head member 104 which carries a forwardlyprojecting pin 105 thereon, eccentrically mounted with respect to the arbor 92. The purposes of the pins 102 and 105 will be hereinafter explained.

An arbor 106 mounted adjacent. the periphery of the frame plates 13 and 14, and bull gear33, carries thereon a dog 107 having a shoulder 108, against which one end of the flat spring109 bears with the other end seated in arecess (not shown) in the rear frame plate 14.

The projected end of the dog 107 engages the teeth of the bull gear 33 preventing its rota t" on in unwinding direction while permitting rotationthereof in winding direc- 'tion.

The rear frame plate 14 has a radial outwardly extending integral projection 111 thereon, in proximity to the differential 34;

A stop or dog member 112 is pivoted to the front face of the rear frame plate 14at a point 113 spaced radially and inwardly of the projection 111. This stop member coniprises a bell crank having an arm 114 which has a perpendicular forwardly extending projection 115, and a laterally extending arm 116 having a T-shaped head portion 117 whichhas rearwardly bent arms 118 and laterally extending projections 119. The forrear frame plate 14, are adapted to abut the radial edge'sof the projection 111 to stop the stop member 112 in its operative and inoperative positions; The projections 119 extend beyond the outer edge of the projection 111 and can be easily gripped by the fingers of an operator to move the stop member 112 about its pivot 113 to operative or inoperative position. hen swung to operative position,

upon engagement of the stop portion 115 with any of the pins 51, the striking mechanism is made inoperative when so desired.

Referringnow more particularly to Figures 2, 3 and 7, the audible signal producing means comprises a pair of bell striking ham- 3 mer arms 121 and 122, the actuation of the two in unison constituting the hour strike and arm 122 being actuated alone to constitutethe ter ing lug at its free end.

arcuateportions 129 and 111 are ecce half-hour strike At their outer ends, arms adapted to be ra'sed and dropped upon gongs 12 and 11 re pectively. The intermediate portion of arm 122 is reversely bent to form a U-sha led portion 123 which is suitably seated wi an arm 12 1- suitably secured to an arbor journaled in the front and rear frame plates adjacentthe differential 33 in proximityto the peripheries of the frame plates, arm 121 being disposed adjacent rear frame plate 11 and having a portion 126 adapted to be disposed normally in the path of movement of pii 1 or gear 49. The inner end of arm is rormed into an arcnatc portion 129. the purpose of which wi 1- hereinafter described. Arm 121 is like provided with reversei x bent U-shapetl po tion 131 Figure 2) the legs of which are embraced by two rolled care 132 formed from laterally projecting lugs extending from one leg. 133 ofa U-shapel supportin member 131. This member mounted for pix al movemen about arbor 127 with leg 3; abutment with the front face of arm 12" other leg 135 being disposed in pro. 1 the rear face of the fro. frame plate 1 Leg 133 also provided with a later-ah; l ng lug 136 having a rearwardlv bent end portion 137, one edge of which is adapted to normally abut the adjacent edge of arm 12 1-. Leg 135'is provided with right -zmgularly extending arm 138 having a forwardly extenrh This lug 139 er tends forwardly through an arcuate slot 186 in the front frame plate 13 and for a short distance beyond the front face of said frame plate (see Figure 1). The purpos of arm 13S and lug 139 will be hereinafter described. The inner end of arm 121 is also pro ded with an arcuate portion 141. Rolled s 112 extendinglaterally from leg 135 are provided for alternate positioning of arm 121. The trica ly disposed with respect to arbor 127 and in the inoperative positions of arms 121 and 122 are dis ,osed in the same Jlane. It will be now apparent that-s nce member is freely rotatable on arbor 127 while arm 121 secured to the arbor. and further since lug 13.7 1 merely abutting engagement with arm when arm 121 is cammed downwardly by pins 51. both arms 121 and 122 are e ev ted in uni- As each pin releases arm 1' in pa ssing, both arms 121. and 122 are grai it actuated downwardly by the weight bf hammers and 126, strikingbells 11 and 12 at the bot tom of each stroke. The operation of gen" 19 carrying pins 51 is so controlled to stop the gear with one pin 51 in engagement with the upper edge of arm 121- a. el 11 i inafter -described in conjunction with the detailed description of the operation of the clock and control mechanism. To prevent arms 121 and 122 from descending farther than isrequired to give an audiblesignal by strikingthe gongs 11 and '12, and to further limit the downward movement thereof in arcuate'portions 129 and 141 of arms 12-1 and" I shall now describe the control mechanism for the striking mechanism, reference being had particularly to Figures 1 ands.

It will be understood that the control mechanism is positioned on the front face of the frame plate 13 between this plate and the dial, with only those parts projecting through the front frame plate as will be so indicated. Pivotally supported on the outer face of the front frame plate 13 are three levers 151, 161 and 171 pivoted at 152,

162 and 172 respectively.

Lever 151 ha." a downwardly extending arm portion having an extension 153 which carries a pivoted spring projected arm 154. The extreme end of the lever 151 has a stop projection 159 against which a lug 155 of the arm is adapted to abut in projected position. Intermediatethe ends of lever 151, a perpendicular rearwardly extending stop lug 156 is provided. This lug extends through a slot- 157 in the front frame plate 13 and is adapted to be moved into the path of a.

stop arm 101 against the pressure of a spring 181. The lug 156 is spaced from the arm 151 to form a recess seat 158 for a purpose to be hereinafter described.

Lever 161, pivoted at 162, extends downwardly and at its free end is provided with an arcuate toothed sector or rack 163, so that the lever is generally L-shaped. Intermediate the ends of lever 161, a finger 164 is pivoted at 165 and is normally spring projected through the action of a spring 167 against a stop lug 166 projecting forwardly from the lever 161, so that it can be temporarily moved downwardly out of the path of the high point of a cam 182 in each rotation of the latter. Adjacent the pivot 162, the lever 161 is provi *d with a rearwardly projecting lug 168; Spring 167 is coiled about the pivot 162 with one end thereof abutting the lower edge of the lug 168 and the other extending through a recess in a rearwardly projecting lug 169 on the finger 164. The teeth of the rack 163 projeoct into the path of movement of the pin 1 5.

Spring 181is coiled about the oivot 151 with one end abutting the upper edge of the lug 168 and the other passing through a recess in the lug 155, with the intermediate. portion thereof passing under the lug 156 through the recess seat 157 and-is offset shipping of movements independently of 'the Lil-J side of the pivot and at its other end, with three lugs 174, 175 and 176, the first and third of which project forwardly whilethe second projects rearwardly througha recess 177 in frame plate 13 and is adapted to be moved into and out of the path of movement of pin 102., Lug 176 has a beveled edge 178 and is adaptedto be moved into and out.

of engagement with the teeth and the end of rack163 of lever 161. Lug 174 projects into the path of movement of lever 151 and is adapted to be engaged by the lower' edge thereof. Due to its weighted end, the lever 171 is normally gravity actuated so that there is always a tendency on the part of this lever to project its other end upwardly for engagement with the teeth of the rack 163 or the lever 151, when not positively actuated in the opposite direction. 1

A fourth lever 183 pivoted at 184 on the frame plate 13 and s aced therefrom is of bell crank formation aving its longer arm 185 extending downwardlv and its shorter arm 186 extending laterally adjacent and above the cannon pinion assembly, the latter arm being in constant engagement with an eccentric cam 187 on the cannon pinion assembly. (See Figure 4). Due .tothe positioning oft-his arm, it is constantly gravity actuated downwardly, so that the longerarm 185 may be moved into and out of a position overlying the slot 188 in the frame plate 13.

The cannon pinion assembly comprises a minute hand shaft 191 projecting forwardly through the frame plate 13 and supporting a minute hand 192 at its outerend, any conventional hour hand gearing operatively connecting this minute hand shaft with the hour band 193 (see Figure 4). As illustrative of this gearing, a pinion 194 on the minute hand shaft drives a gear 195 which, through pinion 196, drives a large gear 197 mounted on a sleeve 198. The stepped cam 182 is provided on the cannon pinion assembly and rotates in the plane of the finger 164, thus being positioned forwardly of and rotating with the gear 197. A drop-off cam 199 is positioned adjacent and behind the cam 187. The cam 199 is provided with two cam shoulders and is of the type which operates its follower, in the instant case the finger 154, throughtwo cycles of operation each revolution. Thus,

the lever 151 may operate through two cycles of operation for every revolution of the cam 199. i

The operation of the winding and striking mechanism is as follows: I

Assuming that the striking mechanism is stationary after astriking period, the cam follower or finger 154 having passed overone of the high points and dropped to a low point of the earn 199, and the brake 73 is slightly vreleased, the motor 16 will wind the main spring through thetrain of gears 23, 26,29

and 32, the last of these being in engagement.

with the bull gear 33 of the differential 34.

At this time, the striking mechanism is held in inoperative'condition by the engagement of lug 175 of the lever 171'with the pin 102, thus retaining the gear 49 in stationary condition. I

' As the bull gear 33 is rotated, the pinions 36 carried thereby, impart rotary movement to the gear 44, employing the teeth of gear 47 as a track therefor. The gear 46 moving with gear 44, rotates the gear '52, which in turn rotates the mainspring arbor 55 by coaction with the gear .54 fixed thereon. As the main spring is wound, the collar 62 threads into the boss 64 carrying the fork 66 of the brake arm 67 rearwardly thus applying the brake 73 to the gear 23 and slowly retarding the winding. The deceleration of the motor 7 trains 61, 76, 78, 82, 84 and pinion 85, all driven from the teeth 61 of the main spring cover plate 59.

Assumingnow that the minute hand 192 hasjust passed the three-quarter hour mark and is in the position shown in Figure 1, the cam follower or finger 154 is at this time resting on one of the high points of the cam 199, and

in reaching this position has released lever,

161 by the engagement of the lower edge of lever 151 with the lug 174, thereby moving the upper end of lever 171 downwardly against the action of the weight 173, moving the lug 176 out of the path of movement.v

of the rack 163.

The lever 161 is thus spring projected to the left by the action of the upper free end of the spring 181 in abutment with the upper edge of the lug 168 so that the end of the.

finger or lever 164 abuts one of the steps of the cam 182, in the illustrated position, the eleven oclock step. The rack is at this time advanced inwardly so that the proper number of teeth thereon are presented to the pin.

105, the coaction of which will be presently described. At this time the arm or lug 156 of lever 151 is in a position in the path of movementof the stop arm 101 (see Figure 3) thereby preventing the striking mechanism from operating.

As the minute hand 192 reaches the hour mark, the cam follower 154 drops off the high point on the cam 199 and is projected upwardly by the spring 181, thus moving thelug 156 out of the path of movement of the ferential is free to operate so that the gear j5unde the expansion influence of the main spring is rotated in a d rection reversed from that in winding and transmits rotative energy to the gear 52 which in turn rotates gear 4,6 (see'Figure 2).

The hull gear 33, which is prevented from reverse rotation by the dog 107, now rema ns stationary so that the differential pinion pivots remain stationary. With the. pinions 36 thus permitted to rotate about stationary pivots, the gear 44 moves in-a clockwise direction asseen. in Figure 2 with its companion gear 16 and through the differential pinions, rotates the companion gears 47 and 419 in a counter-clockwise direction as viewed in Figure 3. The pins. 51 each in turn engage the upper edge of the arm causing both hammers of the striking means to be raised as each pin reaches its lOWS11F 30S1131011,.tl16 hammers and 126 being permitted to fall suddenly bythe disengagement or release of thearm 124 from the pin.

During the strlkingoperation, the gear 19 through pinion 91 rotates arbor 92 in a clockwise :directiomthus rotating the pin 105 on the head portion 104 'which atthe top of its path of movementi engages the teeth of the rack 163. As the rack 163 is .movodto the right, the beveled edge 178 of .thc-lug 1' 6 is engaged by eaclrsuccessive tooth of the rack, and end of lever 17]: being cammed downwardly in passing, and dogg ng the rackagainst return movement after 4 1 Mr. 1 i. 1'-r J1 each tron Rik- 3b by the rug in). he reslationship between each striking impulse transmitted tothe hammers by each pin 51 1S suclras to account for one complete revolution of thearbor 92, and consequently pin 105,

which in turn upon each revolution moves the rack 163 one tooth to the right, each tooth -.acconnting for one strike andthus controlling the number of, strikesto'be -ma'de by both hammers in unison.

hen the lug 17 6 has passed the end tooth 179-of the rack, theweight 173- acts to raise heater governor '99 by its engagement with pinion 97 on its arbor'98, so that the governor controlsthe speed and smoothness of operation of the striking mechanism.

1 are struck on the hour, while only one gong The control part-s are now in a posit-ion preventing the operation of the striking mechanism until the next striking interval is reached.

As the minute hand approaches the quartor-hour point, cam follower or finger 154 is again depressed against the pressure of spring 181, but the high point or cam199 effective at this time is not quite as high as the one efi'ective prior to the hour interval, so that lever 151 is not moved outwardly as 'far as prior to the hour interval. Hence lever 171 is not cammed downwardly by the engagement of the lower edge of lever 151 with lug 17 1, whereby lever 161 is not released for J swinging movement to the left (see Figure 1). Lever 151 is, howev r, moved sufficiently to the right to cause the lug to move out of the path of movement of pin 102 and. to place the lug 156 in the path of movement 7' of arm 101, (see Figure Thus gear 93 will rotate slightly until arm 101 engages lug 156. At this time, cam 187 on the cannon pinionasscmbly will have permittedarm the striking mechanism. This operation is,

however, limited to one revolution of gear 93 due to the prompt raising of lug 178 by the action of weight 17 3 of lever 171 into the path of the end 179 of the rack 103 of lever 161, thereby permitting lug 175 to promptly assume its position in the path of movement of pin 102. This rotational movement of gear 93 is only sullicient to permit one pin 51 to ride over the edge of arm 124. Since arm 121 is at this time in elevated-position, and arm 185 will permit but-a slight movement of lug 139 in the arcuate slot 188, only arm 122 and its hammer 126 will drop, resulting in a sounding of only gong 11. The succeeding pin 51 of gear 49 will only engage arm 124 su'lficiently as the striking mechanism is brought to rest to slightly raise both arms 1'21 and 122.

It will thus be apparent that two gongs giving a distinct harmonizing audible signal is struck on the half-hour.

As the minute hand proceeds in its movement around to the threequarter hour point, the control parts remain in the same position as they assume following an hour striking period hereinbefore described.

\Vhen the minute hand again reaches'the three-quarter hour point, the cam fol-lower or finger 154 is again depressed against the pressure of spring 181 moving the lug 175 out of the path of stop pin 102, lug 156 intothe' path of stop arm 101, and the lug 176 out of the path of the rack 163, whereby rotation of the hour hand.

Hence in the next operation of the'strikin 'mechanism at the end of the hour period, the crack member 163 will have to be moved outwardly through the space of one more tooth before the lug 176 can swing upwardly in advance ofthe tooth 179, resulting in one more striking impulse being given the'hammer 126, at the next strikingoperation. This extra impulse will be added to each successive hour striking operation from one oclock to twelve oclock, owing to the finger 164 moving inwardly to a greater degree in contacting with the successively lower step of the cam 182 at successive striking intervals.

It will be evident from the foregoing that theclock mechanism and striking mechanism both derive their operating energies from a single constantly energized electric motor so that the operation of the clock continues indefinitely without manual winding of any spring. The continuously acting torque of the motor effective on the main spring of the clock movement at all times excepting during a striking period, results in the tension of this clock spring being maintained between very close limits, approximating a uniform tension on the spring at all times. It will be apparent that this augments the time keeping accuracy of the clock. 'When the main spring tension is such that the s ring is in fully wound condition, the forke end 66 of the brake lever 67 will have been moved rearwardly by the rearward movement of the collar 62 and its flange 65 impinging upon the fork 66 as the collar threads into its threaded. boss, thus applying the brake 73 by the transmission of rearward pressure to the brake shoe 75 which will inturn frictionally imping upon the gear 23, thereby stalling the motor.

The motor will remain in stalled condition until the brake 73 will have been moved forwardly slightly by the unwinding of the main spring, thus relieving the pressure on the gear 23, when the constantly energized motor will again energize the gear train to the differential.

Since the tension of the main spring is maintained between very close limits, it will be evident that the motor will energize the gear train to the differential at very short intervals. In view of this condition, it will be further apparent that the motor will be active during practically every striking period. While I have hereinbefore described the operation of each gear train, namely (1) from the motor to the main spring through the differential and (2) from the main spring to the striking mechanism, it will be understood, that while a condition may arise when each train may operate independently of the other, due for example to a failure of the current in the line, an instant or so prior to the striking period and a resumption of the line current shortly after the expiration of a striking period, that generally in the normal operation of the device, owing to the frequency of the intermittent brake release, and

the consequent energization of the gear train from the motor to the differential as hereinbefore explained, the striking operation will occur concurrently with the energization of the gear train from the motor to the differential.

During this concurrent operation, all the energy transmitted from the motor to the differential is taken up by the striking mech-' anisms due to the fact that the relative arrangement of the gear trains from the main spring to the differential and from the motor to the differential is such that even though the motor is operating, the main spring will still unwind slightly during a striking period. As viewed in Figures 2 and 3, during this operation, the bull gear 33 is rotated in a counter-clockwise direction. The relative movements of the various parts of the differential are such that with the bull gear turning in a counter-clockwise direction, the slight, movement of the gear 44 in aclockwise direction due to the slight unwinding of the main spring permits the teeth of the gear 44 to act as a track for the pinions 36 so that the gear 49 rotates in a counter-clockwise direction. Upon such rotation of the gear 49, the pins carried thereby will operate the hour striking hammer through the coaction therewith of the arm 127.

It is to be noted, that since the energy transmitted bythe motor during a striking period is entirely exhausted by the striking mechanism and that since the main spring is unwinding during the striking period, as soon as the striking mechanism ceases to operate by virtue of the stopping thereof by the auto- 'matic operation of the control means, the energy transmitted subsequently to the difthe motor'will be installed by the applica-'.

ti on of the brake 73 upon the gear 23. v

If it is desired to render the striking mechanism inoperative, the stop arm 114 may be rotated to the position indicated in dotted lines in Figure 3, when the lug 115 will lie 'strikingmechanism and clockworks' in the path of movement oi-tlie pins iii :2 upon engagement thereof, the 'prevented ifrom:rotation.

Itwill he evident from the foregoin 'that shou'hl the line current failduring a st ming period thereby dcenergI 'n unotor,'the -mziin spring will nevertneless carryover the operation of" -king mechanism, thus inthe suring a completion of the striking periodregardless ofthezfailuroof the line current.

It is tohennderstood that the term strile ing mechanism is :not limited to devices striking agong, or toithat part Oi the meclnn nism which operates upon an instrumcnt-ality acting as the scurcoofan an'dihle signal, for

example such as athe hanim er, but i is intended toembrace all forms of a))aratus-desi netl -to audibly or otherwise indicate predetermined time "periods in the operation of "clock.

Sofar as I'am eware,hltam.the first-in -the art to provide a striking clock Where-indie are both actuated'bvthe main springtand wherein a single constantly energized riiiotoi operates the striking 'mechamsm during a striking period and is adapted to wind the main spring betweenstriking periods.

The novelarrangementrof gears and the =interposition of the difi'eient-ialxand the coaction'the-rewith of the main spring ofthe clockby the slight unwinding of the latter during a striking'period, renders'the single motor sufficient for purposesof operating both the clock'mechanlsm and the striking mechanism.

lVhile I have shown what I regard as a preterred embodiment of my invention, it 'will he understood that modifications and rearrangements may he made therein by those skilled inlthe art without departing from the spirit and scopoof the appended "claims or the essence of the invention.

lVhatI claim: as my'invention and desire to secure by Letters Patent is:

1. In combination, a clock movement, a main spring, connectionsbetween the two for operating the 'formerby the latter, a

striking mechanism, means for controlling the striking mechanism, a. constantlyenergized electric motor, agear train connecting the motor Withthe main spring'for effecting Winding of'the springby the motor,a dif- 'iferential in said train, and means'on 'sa-id differential for operating said striking 'mechanism, the diiierential transmitting all of the energy ot' the motor andaportion of the energy of the main spring to the striking mechanism during a striking period for operating said mechanism, "should the motor fail, the differential transmitting energy from the main springto'the striking mech anism for operation thereof during a striking period, and should the main spring be unwound the differential transmitting en- 'ergy zfrom the motor to the striking mechanism for operating sameduring a striking period.

2. In combination, 'a clock movement, a main spring,connections between said movement and main spring for actuating the foriner by the latter, a striking mechanism, a governor, s constantly energized electric HtOl,-9. gear train between the motor and C said main spring for eiiectmg wmdmg ot" the springbythe motor, a diiferentia'l in said train, and a second gear train connecting said differential with said governor means :on the differential for reflecting operation of said striking mechanism during a striking period by the motor and the main spring underthe control of said-governor, the main :epring being wound by the motor through the differential between striking :perio( s,

said gear trains and differential permitting the main spring to operate the strikin 'mechanism during a striking period SllOlllt the motor tail, and control means for the unotor controlled byzt-he main'spring to stop said motor when the main spring is fully Wound.

3. In combination, a clock mechanism :havinga mam spring; a striking mechanism,

means :for controlling :the .=str1king meoha-fl.

nism, a'eonstantlyenergized electric motor.

a ditferential'having albu'llsgear, 'anda spur gear oneach-side of the bull gear, .a gear it-rain connecting saidmotor with saidbull gear, a gear train connecting said -main spring w'ithone of the spur gears, and .e gear train eonnecting said striking mechanism 1 control means :with the other of said spur-gears, to ennble theimotor and the main spring conjointly -to o crate the strikingii In witness whereof, Ihereunto subscribe myname this 10th day of.April,-.1930.

ROSCOE H. VILMETH.

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