US3702529A

US3702529A - Striking mechanisms for clocks

Info

Publication number: US3702529A
Application number: US139034A
Authority: US
Inventors: Francois Zeter; Roger Bellardy; Claude Pouligny; Marc Walter
Original assignee: Jaz SA
Current assignee: Jaz SA; SOC JAZ
Priority date: 1970-05-11
Filing date: 1971-04-30
Publication date: 1972-11-14
Anticipated expiration: 1989-11-14
Also published as: FR2091928B1; CH544334A; FR2091928A1; ES391053A1; CH639671A4; DE2122451A1; GB1343959A

Abstract

A clock striking mechanism includes a counting wheel having peripheral notches spaced by amounts which differ and related to the number of strikes at each striking action, a gear wheel fast with the counting wheel and meshing with a worm. A cam driven by the minute spindle of the clock movement raises a lever when the hour or half-hour is to be struck and a projection on the lever is raised thus leaving the counting wheel free to rotate. The worm is mounted on a spindle which is arranged to open and close a pair of contacts in a supply circuit of a motor and release of the counting wheel frees the worm and its spindle to close the contacts under the bias of a spring. The motor is energized and rotates the spindle to actuate striking mechanism by means of a cam or cams mounted on the spindle. The worm simultaneously drives the gear wheel and hence the counting wheel and striking ceases when the next notch is reached and the lever projection engages therein.

Description

United States Patent Zeter et al.

[541 STRIKING MECHANISMS FOR CLOCKS [72] Inventors: Francois Zeter; Roger Bellardy, bOth'Of Saveme; .Claude Pouligny,

Colmar; Marc Walter, Y Bry-sur- Marne, all of France H w [731 Assignees: Societe Fabrique de l-loriogerie la Vedette, Saverne; Societe Jaz S.A., Paris, France [22] Filed: April 30, 1971 21 Appl. No.: 139,034

30 Foreign Application Priority Data May ll, 1970 France ..70l7055 [52] US. Cl.... ..58/9 [51] 1m. (:1. ..G04b 25/00 [58] Field of Search ..58/8, 9, 10, 12,13, 38

[56] 9 References Cited UNITED STATES PATENTS 2,851,850 9/1958 FOWler...., ..58/8 3,520,126 7/1970 Kolodziej ..58/8

FOREIGN PATENTS OR APPLICATIONS 9/1966 Germany 58/8 NOV. 14, 1972 Primary Examiher-Richardli. Wilkinson I Assistant Examiner-Lawrence R, Franklin Attorney-Stevens, Davis, Miller &'Mosher ABSTRACT A clock striking mechanism includes a counting wheel having peripheral notches spaced by amounts which 'differ and related to the number of strikes at each striking action, a gear wheel fast with the counting wheel and meshing with a worm. A cam driven by the minutespindle of the clock movement raises a lever when the hour or half-hour is to be struck and a projection on the lever is raisedthus leaving thecounting.

wheel and hence the counting wheel and striking ceases when the next notch is reached and the lever projection engages therein.

14 Claims, 8 Drawing Figures I STRIKING MECHANISMS FOR CLOCKS BACKGROUND OF THE INVENTION 1. Field of the Invention The present inventionrelates tostriking mechanisms for clocks. j I g 2. Description of the Prior, Art

Striking mechanisms have been proposed which comprise release means constituted by an assembly of levers actuated from a cam driven by the horological movement at a speed of one revolution per hour, one of the levers co-operating with a counting wheel deter mining the number of strikes. j

} Furthermore, striking devices have been proposed in which the striking is effected by an electric motor. Now these proposed striking mechanisms are intended'more particularly for conventional mechanically. actuated horological movements. .On the other hand it is appreciated that it-is-not desirable to require horological movements, particularly those with a balance wheel drive to effect substantial work which engenders the risk of disturbing the operation of the movement itself.

7 Accordingly, it is an object of the invention to provide a striking mechanism which can be used with an electrical movement'and which can be stopped and restarted without disturbing the movement.

SUMMARY OF THE INVENTION According to .the present invention there is provided in a striking mechanismfor a clock, a counting wheel for determining the number of strikes at each striking action, a gearwheel fast with the, counting wheel, a worm meshing with the gear wheel, aspindle carrying the worm, said spindle being rotatable and axially displaceable in a direction perpendicular to the axis of rotation of the counting wheel and thegear wheel,'an electric motor for rotating said spindle, sound-generating striking means, a supply circuit of the electric motor, contact means in the supply circuit operable to close oropen the circuit bysaid axial displacement of the spindle,and means for releasing the counting wheel and gear wheel whereby to initiate the axiaLdisplacemerit of the spindle of close the contactmeans, energization of the electric motor and actuation to the sound-generating striking means by rotational movement of the spindle for a period of time determined by rotation of the counting wheel.

In a preferred embodiment, the striking mechanism constitutes a unit'assembly with completely independent operation on which a location is reserved for the addition of a strictly conventional horological movement, with a balance wheel drive and .capable of being assembled on an automatic assembly-line in order to provide the best possible conditions for cost price with a novel type of electrical horological movement with a striking mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS Certain embodiments of clock striking mechanisms in accordance with the invention will now be described, by way of example with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is an elevation of one embodiment of a clock striking mechanism in accordance with the invention;

FIG. 2 is a plan view of the striking mechanism shown in FIG. 1;

FIG. 3 is an elevation of one embodiment of control means for the striking members of the mechanism;

FIG. 4 is a plan view of the control means for the striking members shown in FIG. 3; v

FIG. 5 is a'rear view in elevation of the mounting plate of the striking mechanism and showing its incorporation with respect to the horological movement;

FIG. 6 is a plan view of the assembly of the strikin mechanism shown in FIG. 5;

FIG. 7 is a plan view of means enabling automatic stopping of the action of the striking mechanism during a twelve hour period; and

FIG. 8 is a view in section of one embodiment of a counting wheel and of a toothed wheel formed by moulding integrally.

In FIGS. 1 and 2, there are shown a main plate 1 and rear plates 2, 3 and 4, interconnected by posts or other cross-pieces and on which there is mounted a striking mechanism which includes release or starting means constituted by a cam 5 fast with -a spindle 6 of the horological movement making one revolution per hour. The earn 5 is rotated in the sense A and has two noses 5a, 5b, each having an inclined ramp followed by a substantially radial face.

A control leverv 7. is pivotally mounted on a support 9 and presses under. the action of a spring 8 operative at an elbow part of one of itsarms 7a on the cam 5, the support 9 being mounted eccentrically on a spindle 10 carrying a pinion 11 meshing through the intermediary of a toothed wheel 12 with apinion 13 fast with the spindle 6 of the movement.

The arm 7b is also adapted to abut against a sto which co-operates at its end with one, of the limbs 14a of a stop lever 14 pivotally mounted on a, spindle 15 secured on the plate 1; the lever 14 which is subject to the action of a spring 16at another limb 14b of which for each striking action, is fast on a spindle 21 rotatably mounted between the plates 1 and 3 and carrying a gear wheel 22.

The gear wheel 22 meshes with a worm 23secured on a spindle 24 disposed perpendicularly to the axis 21 and capable of sliding axially asindicated by the double arrow B, B the support members 25, 26 being constituted by arms or tabs rigid with the plates. A gear wheel 27 is mounted on the spindle 24 which is driven through the intermediary of a speed-reducing gear 28 by means of an electric motor 29.

The spindle 24 also carries two

rotary cams

30, 31, which are respectively in contact with

rods

32, 33, fixed "on the

spindles

34, 35, pivotally mounted between the plates 1 and 4, the said

rods

32, 33, carrying at their

ends hammers

36, 37 arranged to contact

bells

38, 39 secured respectively on the plates 3 and 4. It shouldbe understood that the bells can be replaced by gongs. or any other sound-producing means.

During their rotation, the earns 30, 31 raise the

hammers

36, 37 which fall again coming into contact with the

bells

38, 39.

and connected at 42 to one of the terminals of an electric current source, the said strip 41 carrying at its free end a contact 44 arranged to contact a contact 45 fixed on an insulating support 46 and electrically connected to the other of the terminals of the electric current source for supplying the motor 29. The spindle 24 which can be displaced axially, is normally biased in the direction of. the arrow B, by a spring 47 supported by the support member 25.

A disc 48 carrying graduations 48' corresponding to the notches 19 of the counting wheel is fast with the spindle 21 and can be seen through a slit 49 provided in the plate 1. This arrangement enables the positionof the counting wheel 20 to be adjusted in order to control the number of strikes.

The striking mechanism operates as follows:

As indicated'in FIGS. 1 and 2, the counting wheel 20 is normally locked by the stop lever 14 of which the end 18 is engaged in one of the notches 19 and the spindle 24 is in the position in which it is in the sense of the arrow B, compressing the spring 47 so that the contacts 40, 45 are spaced apart from one another, and thus interrupting the supply circuit of the motor 29 which is therefore at rest.

The cam 5 is rotated in the sense of the arrow A, at the speed of one rotation per hour, the arm 7a of the control lever 7 follows along the inclined ramp of the nose 5b, so as to raise the lever 7 which rests on. the abutment 50 and to bring it into the position shown in chain line in FIG. '1.

To avoid contact between the arm 7b and the toe 51 of the arm 14a of the stop lever 14, use is made of the eccentric mounting of the pivot of the lever 7. In effect, by the rotation of the pinion ll driven by the gear wheel 12 and the pinion 13, because of a complete rotation in thirty minutes, there is imposed by the action of the eccentric 9 on the lever 7 an elliptical trajectory to the end of the arm 7b and, as a consequence, there is no engagement between the latter and the toe 51, during the upwards path of the lever 7. A surface of said toe 51 defines an inclined plane 51a. It is also possible to conceive asimplified device in which the lever 7 pivots about a fixed pin, the traverse of the toe 51 being effected by making use of the resilient deformation of the end of the arm 7b in the direction perpendicular to the displacement of the lever 7. In order to allow sliding, the rear edge of the arm 7b must be inclined.

This latter proposal, which is simpler than that of an eccentric, requires nevertheless, a larger energy output from the horological movement.

When the arm is at the peak of the nose 5b, that is to say at an hour position or at a half-hour position, the lever 7 moves rapidly into a trough of the cam 5, whilst passing from the position shown in chain lines to the position shown in full lines. During downwards passage the end of the arm 7b encounters the toe 51 of the stop lever 14, which latter pivots about the spindle 15 and momentarily disengages from one notch 19 of the counting wheel 20.

Under the action of the thrust of the spring 47, the worm 23 operates as a toothed rack causing the wheel to turn through several degrees in the sense of the arrow F, so that the end 18 of the lever 14 then rests on the periphery of the wheel 20.

After'displacement of the spindle 24 in the direction of the arrow B the resilient strip 41 being no longer biased by the end 40 of the spindle 24, allows the contacts 44 and 45 to make contact, thus completing the supply circuit of the motor 29 which can then drive the spindle 24 and the worm 23 through the speed-reducing gear 28. The worm 23 drives rotationally the gear wheel 22 and as a result the counting wheel 20 with which it is rigid.

At each rotation of the spindle 24, the

cams

30 and 31 move angularly raising successively the

hammers

36, 37 which in their fall strike the

bells

38 and 39.

As soon as a notch 19 of the counting wheel 20 presents itself below the end 18 of the lever '14, the latter, forced by thespring l6, pivots into the notch and stops the rotation of the counting wheel and of the spindle24carrying the

cams

30,31.

The counting wheel 20 being locked by the lever 14 and the motor 29 being energized since the contacts '44 and 45 are in contact, it follows that the gear wheel 22 rigid with the counting wheel cannot turn and that by reaction the worm 23 thus engages the spindle 24 in the direction of the arrow B by the action of screwing on the teeth of the wheel 22.

The spring 47 being compressed and the end 40 of the spindle 24 returning the resilient strip 41, the electrical contact is interrupted between the contacts 44 and 45, so that the motor 29 is no longer energized and thus stops.

The striking mechanism is thus again in the initial condition as shown in FIGS. 1 and 2 and it is thus ready for afresh striking action at the following full hour or half-hour.

According to one embodiment of the mechanism, a complete rotation of the counting wheel 20 corresponds to a program of striking extending over a period of twelve hours. This period of time corresponds to a total of strikes of each of the two bells (l 2 3 12), that is 78 times for the hoursand 12 for each of the half hours. The ratio of de-multiplication between the worm 23 and the wheel 22 isthus exactly 90, because one turn of the spindle 24 corresponds to one striking action. t

Normally the striking mechanism hereinbefore described and shown in FIGS. 1 and 2 enables the production of identical strikes bim-bam or dingdong both for the hours and for the half-hours. It is however possible to differentiate these latter by striking only one of the bells, by means of the mechanism illustrated in FIGS. 3 and 4. On the spindle 6 carrying the cam 5, there is mounted a second cam 52 which cooperates with one of the ends of an intermediate lever 53 pivotally mounted on a spindle 54 secured on the plate 1 and of which the other end is in contact with an extension 33a of the rod 33 of oneof the hammers 37.

By the rotation of the cam 52 and through the intermediary of the lever 53 after its passage over the nose 52a of the cam, it is possible to hold raised once an hour and at the instant of the striking,'the hammer 37. Only the hammer 36 can strike the bell 38 at this moment. At the following initiating or triggering action, that is to say, after half a rotation of the spindle 6, the hammer 37 is freed; when the lever 53 is on the lower portion 52b of the cam which is closest to the spindle 6. It is clear that according to the relative disposition of the cams 5 and 52, the striking on a single bell or on both bells willbe produced either at the hours orat the half-hours. I

In order to match the striking mechanism with the horological movement, provision is made for acting on the lever 14, by means of a push-button not shown, acting in the direction of the arrow X, in order to free, at will, the counting wheel 20.

This operation must be effected prior to starting the clock or after a voluntary, prolonged, stoppage of the striking mechanism. Stoppage of the striking mechanism is effected by displacing a finger 55 pivotally mounted abouta spindle 56, in such a manner as to act on the end of the strip 41 and to hold apart the contacts 44, 45 in order to interrupt the supply to the motor 29.

Finally, the temporary stoppage of the striking mechanism, particularly during the night, maybe provided by means of another lever not shown, which holds the

hammers

36, 37 away from the bells. In this case, the mechanism continues to operate but without striking, and it is not necessary to re-match the striking mechanism when it is brought into operation again.

In FIGS. 5 and 6, there is illustrated another embodiment of the striking mechanism in accordance with the invention in which the striking mechanism constitutes a unit assembly with completely automaticoperation, in whicha space is reserved for the addition of a strictly conventional horological movement, and particularly a balance wheel movement. This arrangement enables assembly on a single automatic assembly belt in order to bring about the best conditions for the cost of manufacture of a novel kind of electrical horological movement with a striking mechanism.

lnFlG. 5, a rear view is illustrated of the mounting comprises notches in which the nose 83 of the stop lever 78 is capable of being engaged thus locking the counting wheel.

A micro-electric motor 86 is mounted on the plate 63 and provides control of the striking mechanism and of which the rotor is prolonged by a worm not shown in the drawing and driving an intermediate transmission 87 comprising a second worm 87a meshing with a wheel 88 secured on a rotary shaft 89 slidably axially mounted in arms 90 and 91, the said shaft 89 carrying a worm 92 meshing with a control wheel 111 rigid with the counting wheel 84. v I The intermediate transmission 87 is secured on a spindle 93 rotatably mounted in flexible arms 90 and 94 of the plate 63. The end 95 of the spindle 89 is arranged to contact with the plate contra-pivot 96 of the resilient strip 97 secured at 98 on a bent arm of the main plate 63. The strip 97 is connected to the supply circuit of the electric motor, carrying at its free end a contact 99, movable contact, which is arranged to contact a contact 100, fixed contact, connected to the other end of the electrical circuit. A cylindrical member 101 comprising two cams-101, 102 is secured on the spindle 89, on which cams the ends of

rods

104, 105 of the

hammers

106, 107, abut, whichstrike the bells or gongs as are hereinbeforedescribed.

One of the rods 104 of the hammer 107 is connected to a lever 108 which is held by a spring 109 against the cam 110 which raises one of the hammers of one of the striking mechanisms, so as to differentiate sounding of the hours and half-hours.

plate 57 which comprises on one side a space for a battery 58 and in its central part for the horological movement outlined by the shape of its front main plate 59,-

the battery, on the plate 57, between the latter and the rear plate 63, the

pillars

64, 65, 66 providing the connection between the plate 63 and the front plate 57. An intermediate plate 67 is secured by the

pillars

64 and 68.

As in the embodiment hereinbefore described, a starting or initiating cam 69 and a earn 110 for raising the hammers are mounted on a spindle 70 which carries a pinion 71 driven by a gear 72 of the horological movement, which rotates in the sense of the arrow C, at the same speed as the minute spindle .73, viz. one turn per hour.

On the mounting plate 57 there is secured a pivot 74 on which is pivoted a control or detent lever 75 carrying at one of its ends a resilient strip 76 having an opening in which is engaged'a nose 77 of a stop lever 78 pivotal about a pin 79.

The control lever 75 likewise carries a pin 80 which abuts the cam 69 under the action of a spring 81 secured to the plate 59.

Furthermore, the lever 78 subject to the action of a I Furthermore, two additionalopenings 112 and 113 are providedin the plate 63, which accommodate two auxiliary hammer shafts for striking a horizontalgong, these hammers being controlled by a conventional system of rods from the shafts of the rods of the

hammers

104, 105.

, As in the hereinbefore described embodiment, the cam 69 making one revolution per hour, acts on one of its noses on the pin which falls into one of the troughs of the cam and the lever 75 biased by the spring 81 drives through the resilient strip 76, the toe 77 of the stop lever 78.

When the end 83 of the lever.78 is disengaged from one notch of the countingwheel 84, the latter isfreed and can freely turn through the axial force of the worm 92 which forces on it the resilient strip 97, in such a manner that in falling the stop lever 78 rests on a tooth of which the size determines the duration of the striking action.

The disengagement of the strip 97 leads the movable contact 99 into abutment against the fixed contact 100, thus closing the electrical circuit and energizing the motor 86 which drives through the spindle 89 the

cams

102, 103, acting on the rods of the

hammers

106, 107

and the counting wheel 84, through the worm 92 and the gear wheel 1 1 1.

As soon as the counting wheel 84 is again locked by the toe 83 of the lever 78, the reaction of the axial thrust on the worm 92 increases, loading as hereinbefore described the strip 97 and causing the separation of the

contacts

99 and 100 and cutting off of the current.

Because of the inertia of the motor 86, the latter continues to turn after cutting off the current so that the distance between the

contacts

99 and 100 is sufficient.

In FIG. 7 there is shown an embodiment of the striking device with an automatic stop of the striking action during twelve of the 24 hours.

On the control shaft 70 there is freely mounted for rotation between the cam 69 and the toothed wheel 71, a wheel 114 driven by a pinion 115 on the countershaft 60 of the horological movement which rotates at a speed of one revolution for each period of 24 hours.

The cam 116 automatically actuates during twelve hours of the 24 hours a lever for raising the hammers, not shown, which prevents the latter from striking, particularly during the 12 hours of the night.

In FIG. 8, there is shown an embodiment of the counting wheel 84 moulded integrally with the control wheel 11] and its spindle 85. What is claimed is: l In a striking mechanism for a clock,

a counting wheel for determining the number of or open the circuit by said axial displacement of the spindle,

resilient means biasing the spindlein the axial direction to close the contact means,

means for releasing the counting wheel and gear wheel whereby to initiate the axial displacement of the spindle to close the contact means, energization of the electric motor and actuation of the sound-generation striking means by rotational movement of the spindle for a period of time determined by rotation of the counting wheel, and a clock movement controlling said releasing means. 2. A striking mechanism according to claim 1 wherein the contact means comprises a flexible conductive strip electrically connected to the said supply circuit, a movable contact member on said strip, and a fixed contact connected to the supply circuit, said contact, when in abutting relationship, serving to complete said supply circuit. 3. A striking mechanism according to claim 1 comprising a spindle supporting the counting and gear wheels, the counting wheel being a moulding integral with the gear wheel and the spindle. 4. A striking mechanism according to claim 1, comprising a second worm mounted fast for rotation with the motor, a gear wheel meshing with the second worm and serving to drive the spindle of the first worm, two main support plates, two arms bent through 90 carried by said support plates and themselves supporting the spindle of the first-mentioned worm, said sound-producing striking means including a first bell,

a second bell, I

respective first and second striking hammers, and

earns cooperating with the striking hammers and mounted on the spindle,

the axes of the motor, of the counting wheel and the shafts of the striking hammers being orientated parallel to .the two said main plates. 7

5. A striking mechanism according to claim 1, wherein said release means comprises a two-armed pivotal control lever,

a cam making one revolution per hour and having two noses, 1

means biasing one arm of the two-armed lever into contact with the cam, and

a stop lever of generally bell crank form one branch of which is engageable-by the other arm of the control lever and the other branch of which cooperates with the periphery of the counting wheel, said other branch being movable away from the counting wheel by the action of the said other arm of the control lever as the said one arm of the control lever disengages from one or other of the noses of the said cam.

6. A striking mechanism according to claim 5, comprising a shaft eccentric with respect to the axis of a spindle of a horological movement arranged to drive the shaft,

said shaft carrying the control lever and being rotatable at such a speed that the stop lever is disengaged from the counting wheel at the same time as the control lever is driven by the cam.

7. A striking mechanism according to claim 5 comprising a resilient strip having an opening therein mounted on the end of that arm of the control lever which co-operates with one of the branches of the stop lever, the said arm of the control lever being engaged on the said branch of the stop lever by said opening. 1

8. A striking mechanism according to claim 5 wherein the .tip of the arm of the control lever which co-operates with one of the branches of the stop lever is resiliently deformable and .has on one of its faces an inclined plane.

9. A striking mechanism according to claim 5 wherein said sound-generating striking means comprises two sound generators and two respective strikers and the release means comprises a second cam rotating once per hour mounted co-axially with the first-mentioned cam and operative selectively to de-activate one of said strikers.

10. A striking mechanism according to claim 1 wherein said sound-generating striking means includes at least one sound generator and a striker, and

said spindle carries a cam for actuating the striker.

11. A striking mechanism according to claim 10 comprising a gear wheel mounted on the cam-carrying spindle, said gear wheel being driven by the pinion of the counter shaft of the horological movement at a speed of one revolution for every 24 hours, and

a cam fast for rotation with said gear wheel,

' an independently operable tion with the counting wheel and having graduations corresponding to the notches of the counting wheel.

13. A clock including a striking mechanism according to claim 1, wherein the striking mechanism forms 1o unit assembly comprising an assembly plate forming a false casing; a conventional horological movement, and an electric supply source mounted on the assembly plate. I

14. A striking mechanism according to claim 1 comprising means for selectively maintaining the contact means in an open condition in which the supply circuit is interrupted. 1

Claims

1. In a striking mechanism for a clock, a counting wheel for determining the number of strikes at each striking action, a gear wheel fast with the counting wheel, a worm meshing with the gear wheel, a spindle carrying the worm, said spindle being rotatable and axially displaceable in a direction perpendicular to the axis of rotation of the counting wheel and the gear wheel, an electric motor for rotating said spindle, sound-generating striking means, means driven by the motor to actuate said striking means, a supply circuit of the electric motor, contact means in the supply circuit operable to close or open the circuit by said axial displacement of the spindle, resilient means biasing the spindle in the axial direction to close the contact means, means for releasing the counting wheel and gear wheel whereby to initiate the axial displacement of the spindle to close the contact means, energization of the electric motor and actuation of the sound-generation striking means by rotational movement of the spindle for a period of time determined by rotation of the counting wheel, and a clock movement controlling said releasing means.

2. A striking mechanism according to claim 1 wherein the contact means comprises a flexible conductive strip electrically connected to the said supply circuit, a movable contact member on said strip, and a fixed contact connected to the supply circuit, said contact, when in abutting relationship, serving to complete said supply circuit.

3. A striking mechanism according to claim 1 comprising a spindle supporting the counting and gear wheels, the counting wheel being a moulding integral with the gear wheel and the spindle.

4. A striking mechanism according to claim 1, comprising a second worm mounted fast for rotation with the motor, a gear wheel meshing with the second worm and serving to drive the spindle of the first worm, two main support plates, two arms bent through 90* carried by said support plates and themselves supporting the spindle of the first-mentioned worm, said sound-producing striking means including a first bell, a second bell, respective first and second striking hammers, and cams co-operating with the striking hammers and mounted on the spindle, the axes of the motor, of the counting wheel and the shafts of the striking hammers being orientated parallel to the two said main plates.

5. A striking mechanism according to claim 1, wherein said release means comprises a two-armed pivotal control lever, a cam making one revolution per hour and having two noses, means biasing one arm of the two-armed lever into contact with the cam, and a stop lever of generally bell-crank form one branch of which is engageable by the other arm of the control lever and the other branch of which co-operates with the periphery of the counting wheel, said other branch being movable away from the counting wheel by the action of the said other arm of the control lever as the said one arm of the control lever disengages from one or other of the noses of the said cam.

6. A striking mechanism according to claim 5, comprising a shaft eccentric with respect to the axis of a spindle of a horological movement arranged to drive the shaft, said shaft carrying the control lever and being rotatable at such a speed that the stop lever is disengaged from the counting wheel at the same time as the control lever is driven by the cam.

7. A striking mechanism according to claim 5 comprising a resilient strip having an opening therein mounted on the end of that arm of the control lever which co-operates with one of the branches of the stop lever, the said arm of the control lever being engaged on the said branch of the stop lever by said opening.

8. A striking mechanism according to claim 5 wherein the tip of the arm of the control lever which co-operates with one of the branches of the stop lever is resiliently deformable and has on one of its faces an inclined plane.

10. A striking mechanism according to claim 1 wherein said sound-generating striking means includes at least one sound generator and a striker, and said spindle carries a cam for actuating the striker.

11. A striking mechanism according to claim 10 comprising a gear wheel mounted on the cam-carrying spindle, said gear wheel being driven by the pinion of the counter shaft of the horological movement at a speed of one revolution for every 24 hours, and a cam fast for rotation with said gear wheel, said cam being effective during 12 hours out of every 24 hour period to render the striker of one sound generator inoperative.

12. A striking mechanism according to claim 1 wherein the counting wheel has peripheral notches and the mechanism further comprises a disc fast for rotation with the counting wheel and having graduations corresponding to the notches of the counting wheel.

13. A clock including a striking mechanism according to claim 1, wherein the striking mechanism forms an independently operable unit assembly comprising an assembly plate forming a false casing, a conventional horological movement, and an electric supply source mounted on the assembly plate.

14. A striking mechanism according to claim 1 comprisiNg means for selectively maintaining the contact means in an open condition in which the supply circuit is interrupted.