Abstract: A horological movement includes an escapement with a magnetic system to generate magnetic force impulses, so as to sustain the oscillation of the mechanical resonator associated with the escapement. In order to make possible an effective self-starting of the assembly formed of the mechanical resonator and of the escapement during a winding of the barrel, after a stop of the horological movement due to the unwound barrel spring, the escape wheel includes teeth and the pallet assembly includes two mechanical pallet-stones arranged to receive, upon starting, at least one mechanical force impulse of the escape wheel via one of the teeth thereof, the mechanical force impulse generating a starting force torque on the pallet assembly that is transmitted to the balance of the mechanical resonator to begin an oscillation of the latter so that the assembly can operate normally after a starting phase.

Abstract: A braking device (100), separate and remote from its guide members, having resilient strips (3; 31; 32) borne by a braking mobile component (10) trapped between a structure (1) and a bolt (6) and movable perpendicularly to the axis of a horological mobile component arbor (30), on which the strips bear, and either all of the bearing forces on the arbor (30) of the strips (3) are exerted within a single angular sector having a centre angle (a) of less than 180°, or, opposite a first straight or convex strip (31) tangentially braking this arbor (30), a second strip (32) allows for relative mobility between the braking mobile component (10) and this arbor (30) in a direction of mobility (DM), the latter being: either parallel to the first resilient strip (31), or wavy and deformable perpendicularly to the direction of mobility (DM).

Abstract: A shock absorbing device including a spring ring able to adopt a mounting position and an attachment position respectively with respect to the support of the shock absorbing device. This spring ring includes, on the external periphery thereof, tabs which engage with a peripheral shoulder of the support of the shock absorbing device provided with recesses which outnumber the tabs. In the attachment position, only some of the tabs are disposed under the peripheral shoulder of the support, the remaining tabs, including locking tabs, respectively housed in locking recesses, of the support. In the attachment position, at least one locking tab housed in a locking recess is surrounded by tabs positioned under the peripheral shoulder.

Abstract: A method of manufacturing a clock or watch component (19; 29) includes (i) providing (E11; E21) a wafer (11; 21) having a single slice (12; 22) including a material of the component, notably silicon, diamond, quartz, sapphire or ceramic, optionally first coating the lower surface of the slice (22) with a lower layer (24), (iii) etching (E12 to E14; E22 to E24) the slice (12; 22) starting from its upper surface to form at least one clock or watch component, (iv) revealing (E15; E25) at least one clock or watch component (19; 29), by removing a layer that served as a mask for etching (E15; E25) and (y) optionally releasing (E26) the slice and the at least one etched clock or watch component by removing the lower layer (24).

Abstract: A shock-absorber device for a wheel arbor of a micromechanical device includes a support which includes a turning-arbor delimited by a rim defining a housing into which a pivot module is inserted. The pivot module includes a setting having a central orifice into which is inserted a bored stone. An endstone is placed on top of the bored stone. The shock-absorber device also includes a spring ring arranged between the support and the pivot module. The shock-absorber device is equipped with a bayonet system for mounting the spring ring. The bayonet system includes a peripheral shoulder under which is formed a circular groove which defines a holding area. The spring ring is equipped on an outer periphery with at least one catch. At least one first notch which leads to the circular groove is provided in the peripheral shoulder.

Abstract: A bearing includes a shaft which pivots in the bearing. The shaft includes, at at least one end thereof, a shoulder via which the shaft is in contact with an opposite surface of the bearing. The shoulder is extended by a pivot engaged in a hole provided in the bearing. The opposite surface of contact of the bearing includes at least one hollow in order to reduce the surface of contact between the shoulder of the shaft and the bearing. Application is made to the production of a bearing for a shaft of a horology movement.

Abstract: Provided are a mechanical part, a timepiece having the mechanical part, and a method of manufacturing a mechanical part that suppresses separation and rotation of a rotating member to a staff member, and can be manufactured at a competitive cost. A escape wheel and pinion 35 as an example of a mechanical part has a staff member 102; an escape wheel 101 with a hole 115 to which the staff member 102 is inserted, and ribs 112 that extend toward the staff member 102; and an annular fastening member 130 that affixes the escape wheel 101 to the staff member 102. The fastening member 130 is disposed touching the ribs 112 and deforming to protrude into the hole 115.

Abstract: An escape wheel & pinion serving as a mechanical component includes an axle and an escape wheel serving as a rotary member having a holder for holding the axle. The axle has a recessed portion into which the holder is fitted. A tapered portion inclined in an axial direction of the axle is disposed in a portion where the recessed portion is in contact with the holder.

Abstract: An escape wheel and pinion includes an escape wheel that has an axle, a web arm which holds the axle, and a rim which has a plurality of teeth. The web arm has a spoke which radially extends from the rim, and a comb including a radial spine and cross beams branching from the spoke.

Abstract: The invention relates to a timepiece component with a part comprising elastic attachment means and securing means arranged to be welded enabling the attachment of the elastic means to be decoupled from the securing means to ensure the welding of the timepiece component.

Abstract: A shock absorber device for an arbor of a timepiece element includes a support including a base cup surmounted by a peripheral rim delimited, opposite the cup, by an upper surface and including an outer wall, the cup and the rim defining together a housing. The shock absorber device further includes a pivot module extending along an axis, the pivot module being arranged inside the housing and being able to cooperate with the arbor. The shock absorber device further includes fastening device including a peripheral shoulder extending from the rim towards the axial center of the cup, and elastic device being arranged between the pivot module and the shoulder to exert a stress on the pivot module.

Abstract: A shock-absorber bearing for a staff of a moving part of a timepiece, the bearing including a support including a housing configured to receive a pivot module configured to cooperate with the staff, and an elastic mechanism configured to exert at least one axial force on the pivot module to retain the module in its housing.

Abstract: This timepiece includes a movement with a diameter of less than 40 mm which comprises a barrel (1) for the housing of a mainspring and of which the diameter is less than the radius of said movement. The barrel (1) comprises a cylindrical lateral wall (2), surrounded by a tooth gear (3), of which each edge (21, 21?) is closed by a disk (4, 4?) traversed axially by an opening (5, 5?) for pivoting of a barrel arbor (7). The height of the housing is between 85% and 97% of the total height of the periphery of the barrel (1).

Abstract: An assembly including a member made of a first material, which is axially driven into a circular aperture of a part made of a second material that is brittle, using an intermediate part made of a third material and mounted between the member and the part is disclosed. The intermediate part is a continuous cylinder including a hole for receiving the member so that the intermediate part absorbs radially and in a uniform manner, at least part of the axial driving force of the member. The part includes pierced holes forming elastic deformation units distributed around the circular aperture thereof for absorbing any of the radial force not absorbed by the intermediate part, so as to secure the assembly in a non-destructive manner for the part.

Abstract: A method for manufacturing a component in a substrate including: a) modifying a structure of at least one region of the substrate to make the at least one region more selective; and b) chemically etching the at least one region to selectively manufacture the component.

Abstract: The invention relates to a system of assembling a member, made of a first material, in the aperture of a part made of a second material having no usable plastic domain, using an intermediate portion (7, 27, 47, 67, 87) made of a third material, mounted between said member and said part. According to the invention, the part is accommodated against a first level (6) of the intermediate portion and is resiliently locked on a second level of the intermediate portion by the member in order to secure together the unit comprising the member—intermediate portion—part. The invention concerns the field of timepieces.

Abstract: The invention relates to a bearing comprising a sintered ceramic body traversed by a hole. According to the invention, the body includes a top surface and a bottom surface each of which includes a functional element communicating with said hole.

Abstract: A timepiece includes: —a barrel bridge (33), and—a barrel mounted on the barrel bridge, the barrel having: —a drum (20) which includes an end wall and side walls, —an arbor (14) which passes through the center of the drum, —a leaf spring housed in the drum and engaging at a first end with the arbor and at a second end with the drum, and—a cover (28) through which the arbor passes freely and which closes the drum, —a ratchet wheel (30) secured to the arbor to tension the leaf spring. The drum is pivoted by a first ball bearing including an intermediate ring (36), an inner ring (42) secured to the arbor and an outer ring (38), one of the intermediate ring and the outer ring being fixed to the barrel bridge and the other being secured to the end wall.

Abstract: The timepiece movement includes a shock absorber bearing for a rotating wheel set, formed of an elastic device having a rigid central part and an elastic structure connected to said central part and extending at the periphery thereof, the central part having an aperture in which a pierced jewel is arranged and being materially connected to the timepiece movement via the elastic structure. This bearing further includes an endstone, which forms a top stop member for the pivot of the rotating wheel set and is assembled to said central part so as to move integrally therewith. This endstone extends at least partially above the elastic structure and is secured to the central part by a material connection between said central part and the bottom surface of the endstone.

Abstract: Timepiece sub-assembly including a spacer for guiding a pivoting wheel set on a bottom plate and including a shoulder for cooperating with a housing in the bottom plate and a stop surface for abutting against the bottom plate. It includes a drive means fixed to the wheel set, arranged to slide relative to the spacer with an axial shake, determined between a first stop position between a collar of the wheel set and a front face of the spacer, and a second stop position between a stop surface of the drive means and a rear face of the spacer. The wheel set includes, opposite the collar, a machined portion arranged to cooperate with a complementary machined portion of a display element to fixedly secure the display element to the wheel set.

Abstract: A timepiece bearing has a bearing member of unitary construction that is provided at least at one end portion of a shaft member for undergoing rotation around an axis and that regulates movement of the shaft member in axial and radial directions of the shaft member. An elastic member applies an urging force in an axial direction of the bearing member to hold the bearing member in contact with the shaft member. A frame member supported by and fixed to a support member contains the bearing member. The elastic member is provided so as to establish connection between the bearing member and the frame member. The shaft member is configured to undergo rotation around the rotational axis while the shaft member and the bearing member are held in contact with each other by the elastic member.

Abstract: Anti-shock device for the protection of a timepiece component pivotally mounted between a first and a second end in a chamber. The component is freely mounted in the chamber between pole pieces, which are distinct from the component and located in proximity to the chamber and the device includes a device for attracting the first end held in abutment on only the first pole piece, and a device for attracting the second end towards a second pole piece, the devices for attracting the first end and the second end, which are of magnetic and/or electrostatic nature, can move along an axial direction between stop members.

Abstract: A timepiece includes a frame (1a, 1b) and a gear pivotably mounted on the frame (1a, 1b) via at least one pivoting member (5a, 5b) which includes a bearing and a pivot inserted in the bearing, at least the contact surfaces of the bearing and the pivot being made from at least one material with an intrinsically low friction coefficient and a low wear rate, the gear including at least one plate (2a, 2b) provided with a first hole (3a, 3b). The pivoting member includes a first plate (6a, 6b) provided with a second hole (8a, 8b) and forming the bearing, and a second plate (7a, 7b) provided with a small rod (9a, 9b) inserted in the first and second holes and forming the pivot, one of the first (6a, 6b) and second (7a, 7b) plates being rigidly connected to the gear and the other to the frame (1a, 1b).

Abstract: A pivot organ (5a, 5b) designed to allow the rotation of a piece (3) of a clockwork movement around an axis of rotation, includes two elements: a pivot (7a, 7b) and a bearing (6a, 6b) receiving the pivot (7a, 7b), one being integral with the piece (3) and the other being integral with the frame (1) of the movement. The elements (6a, 6b, 7a, 7b) have shapes at their opposite surfaces such that the section of one of the elements along a plane perpendicular to the axis of rotation is circular, the section of the other element along the plane being non-circular, so as to reduce the contact surface between the pivot (7a, 7b) and the bearing (6a, 6b). At least the contact surfaces of the two elements against each other are made from at least one material intrinsically having a low coefficient of friction and a low wear coefficient.

Abstract: The invention concerns a method of making a controlled or reduced contact or contactless transmission in a timepiece movement. At least one pair of opposing cooperating surfaces of said timepiece movement, one of which drives the other or is supported thereby, is made or transformed by applying a surface or through treatment conferring an electrostatic and/or magnetic charge of the same polarisation and/or magnetisation on said opposing cooperating surfaces, such that said opposing components tend to repel each other when they are moved closer to each other. Said treatment consists in creating or depositing at least one thin layer on said cooperating surface and/or on said opposing cooperating surface. The invention also concerns a timepiece mechanism incorporating at least one pair of opposing components, one of which drives the other or is supported thereby, said pair being made or transformed by implementing this method.

Abstract: Smooth timepiece bearing (1). It includes a core (5) of plastic material injected into a cavity of revolution (4) of an outer cage (3). It also includes an inner cage (2) contained within said cavity (4) and said core (5) is injected between said inner cage (2) and said outer cage (3). Said core (5) can move with an operating clearance relative to said outer cage (3) and cannot be removed from said outer cage (3) and can move with an operating clearance relative to said inner cage (2), and cannot be removed from said inner cage (2).

Abstract: Repairs of clocks with worn wheel pivots may be made with a ball bearing pivot wheel support system. The system may utilize a standard sized ball bearing and a bushing in frictional engagement with an inner race of the ball bearing. The bushing may be bored to provide frictional engagement with the pivot wheel so that the pivot wheel may rotate without relative motion between the wheel pivot and the bushing.

Abstract: A timepiece includes a striking member and a struck member that is driven when struck by the striking member, at least one of the striking member and the struck member being made from a metallic glass alloy.

Abstract: The present invention aims to provide a bearing structure allowing direct adjustment between itself and an opposing bearing even after assembly and a watch equipped with the same. A bearing structure of a watch rotatably supports a forward end portion of a shaft of a wheel with respect to a base body, and includes: a bearing, a bearing support body supporting the bearing and having a male screw portion on an outer peripheral surface concentric with the shaft of the wheel, and an adjustment nut equipped with a female screw portion threadedly engaged with the male screw portion of the bearing support body, regulated in its displacement in the extending directions of the shaft of the wheel by the base body, and adapted to adjust the position of the bearing with respect to the extending direction of the shaft via the bearing support body.

Abstract: A differential gear for watch movement may include a central shaft whereon first and second wheels are rotatably mounted, each of which is provided with a toothing arranged to mesh with a toothing of at least one satellite borne by a satellite carrier also mounted on the central shaft. The first and second wheels may be configured to engage first and second mobiles of the watch movement, the central shaft including a toothing configured to engage a third mobile of the watch movement. Further, the satellite carrier may be secured in rotation with the central shaft by a friction device comprising a tube having a first portion arranged bearing against the central shaft and at least one second portion arranged bearing against the satellite carrier. The tube may include a substantially cylindrical skirt, wherein at least one first tab is formed in such a way that it exerts a force having a radial component on the satellite carrier.

Abstract: The part is made from a plate (1) made of a brittle material, such as glass, quartz or silicon and includes at least one aperture (2, 4, 6) for driving in a shaft (5). This aperture is characterized in that it includes alternately rigidifying and positioning zones (8) and resilient deformation zones (10). Application to securing a shaft onto the moving parts of a timepiece movement.

Abstract: The timepiece movement includes a shock absorber bearing (70) for a rotating wheel set, formed of an elastic device (72) having a rigid central part (74) and an elastic structure (26) connected to said central part and extending at the periphery thereof, the central part having an aperture in which a pierced jewel (10) is arranged and being materially connected to the timepiece movement via the elastic structure. This bearing further includes an endstone (82), which forms a top stop member for the pivot of the rotating wheel set and is assembled to said central part so as to move integrally therewith. The bearing is characterized in that the endstone extends at least partially above the elastic structure and in that it is secured to said central part by a material connection between said central part and the bottom surface (83) of the endstone.

Abstract: A timepiece wheel train includes a rotating body with a shaft unit, a bearing unit that rotatably supports the shaft unit of the rotating body, and a lubricating oil in which powder from a diamond-like carbon film is dispersed disposed between the shaft unit and the bearing unit.

Abstract: A timepiece includes a frame (1a, 1b) and a gear pivotably mounted on the frame (1a, 1b) via at least one pivoting member (5a, 5b) which includes a bearing and a pivot inserted in the bearing, at least the contact surfaces of the bearing and the pivot being made from at least one material with an intrinsically low friction coefficient and a low wear rate, the gear including at least one plate (2a, 2b) provided with a first hole (3a, 3b). The pivoting member includes a first plate (6a, 6b) provided with a second hole (8a, 8b) and forming the bearing, and a second plate (7a, 7b) provided with a small rod (9a, 9b) inserted in the first and second holes and forming the pivot, one of the first (6a, 6b) and second (7a, 7b) plates being rigidly connected to the gear and the other to the frame (1a, 1b).

Abstract: The device for pivoting an arbour (11) in a timepiece, includes two pivots (12, 12?; 32) each forming one end of the arbour and two bearings for receiving the two pivots. Each of the pivots includes an approximately cylindrical portion (19, 19?; 39) and a convex rounded portion (13. 13?; 33) that extends the approximately cylindrical portion and gradually decreases in the direction of the end. Each of the bearings includes a pivoting structure (25; 35) held in place elastically, which includes an approximately cylindrical passage traversed by said approximately cylindrical portion (19, 19?; 39) of one of the pivots. The pivoting structure also includes a bearing surface against which the end of said pivot will abut.

Abstract: A timepiece includes a platen (10) and a barrel mounted on the platen, the barrel including: a drum (20) with a bottom and side walls; a shaft (14) extending through the drum at the center thereof and provided with pivoting elements (40, 54) on the platen; a leaf spring provided in the drum and co-operating with the shaft at one end and with the drum at the other end; and a lid (28) through which the shaft extends and closing the drum, a ratchet wheel (30) being kinematically connected to the shaft for winding the spring. According to the invention, the drum is pivoted via a first ball bearing (34) having a bushing (36) connected to the platen and another bushing (38) connected to the bottom of the drum.

Abstract: A pivot organ (5a, 5b) designed to allow the rotation of a piece (3) of a clockwork movement around an axis of rotation, includes two elements: a pivot (7a, 7b) and a bearing (6a, 6b) receiving the pivot (7a, 7b), one being integral with the piece (3) and the other being integral with the frame (1) of the movement. The elements (6a, 6b, 7a, 7b) have shapes at their opposite surfaces such that the section of one of the elements along a plane perpendicular to the axis of rotation is circular, the section of the other element along the plane being non-circular, so as to reduce the contact surface between the pivot (7a, 7b) and the bearing (6a, 6b). At least the contact surfaces of the two elements against each other are made from at least one material intrinsically having a low coefficient of friction and a low wear coefficient.

Abstract: A differential gear for watch movement may include a central shaft whereon first and second wheels are rotatably mounted, each of which is provided with a toothing arranged to mesh with a toothing of at least one satellite borne by a satellite carrier also mounted on the central shaft. The first and second wheels may be configured to engage first and second mobiles of the watch movement, the central shaft including a toothing configured to engage a third mobile of the watch movement. Further, the satellite carrier may be secured in rotation with the central shaft by a friction device comprising a tube having a first portion arranged bearing against the central shaft and at least one second portion arranged bearing against the satellite carrier. The tube may include a substantially cylindrical skirt, wherein at least one first tab is formed in such a way that it exerts a force having a radial component on the satellite carrier.

Abstract: The invention relates to a timepiece component (1) that has an aperture (7) for receiving a support element (3) and includes a clamping system (13) for exerting radial force, allowing said timepiece component to be secured to said support element. According to the invention, the clamping system (13) includes a radial clamping device (15) that has a crown (6) for exerting said radial force and a concentric, blind recess (8) spaced apart from said aperture, for allowing said crown to travel. The invention concerns the field of timepieces.

Abstract: The invention concerns a vertical type uncoupling device, in particular in an automatic watch winding mechanism that includes an oscillating mass and a gear train connecting the oscillating mass to a barrel (9), wherein said gear train includes a direction reverser device (11, 12), a reduction gear (13, 14, 15, 16) and the uncoupling device (20). The uncoupling device includes two coaxial wheels (17, 7) that can be coupled in rotation in one direction owing to respective Breguet toothings (21, 22) arranged on the opposite flanks of said wheels. The coaxial wheel (17), which is mobile in the axial direction, is secured to a sliding arbour (18), which is mounted so as to rotate and slide in fixed bearings (24, 25). A return spring (26) includes an elastic strip that abuts against one end of the sliding arbour (18) to tend to engage and keep meshed the Breguet toothings. This design reduces friction and saves space. Other applications of this type of uncoupling device in a watch movement are described.

Abstract: The present invention aims to provide a bearing structure allowing direct adjustment between itself and an opposing bearing even after assembly and a watch equipped with the same. A bearing structure of a watch rotatably supports a forward end portion of a shaft of a wheel with respect to a base body, and includes: a bearing, a bearing support body supporting the bearing and having a male screw portion on an outer peripheral surface concentric with the shaft of the wheel, and an adjustment nut equipped with a female screw portion threadedly engaged with the male screw portion of the bearing support body, regulated in its displacement in the extending directions of the shaft of the wheel by the base body, and adapted to adjust the position of the bearing with respect to the extending direction of the shaft via the bearing support body.

Abstract: The process comprises the following steps: a) a first element (3) or a plurality of said first elements (3) is/are machined in a first silicon wafer (1) keeping said elements (3) joined together via material bridges (5); b) step a) is repeated with a second silicon wafer (2) in order to machine a second element (4), differing in shape from that of the first element (3), or a plurality of said second elements (4); c) the first and second elements (3, 4) or the first and second wafers (1, 2) are applied, face to face, with the aid of positioning means (6, 7); d) the assembly formed in step c) undergoes oxidation; and e) the parts (10) are separated form the wafers (1, 2). Micromechanical timepiece parts obtained according to the process.

Abstract: The invention proposes an analogue display member (10) fitted to a timepiece, of the type including a main body in which an arbor hole is arranged, characterized in that the main body is made of silicon based crystalline material. The invention also proposes a timepiece provided with such a display member (10). The invention also proposes a method of fabricating analogue display members (10) to be fitted to timepieces, each analogue display member (10) including a main body, characterized in that it includes at least one step of micro-machining a wafer of silicon based crystalline material to form at least one main body in said material.

Abstract: Assembly element (18) made in a plate of brittle material, including an aperture (32) provided for the axial insertion of an arbour (26). The inner wall (33) of the aperture (32) includes elastic structures (34), which are etched into the plate and which each include at least one support surface (36) for gripping the arbour (26) radially in order to secure the assembly element (18) relative to the arbour (26). The assembly element (18) includes a first series (S1) of elastic structures (34) etched in a top layer (39) of the plate and a second series (S2) of elastic structures (34) etched in a bottom layer (41) of the plate. A timepiece may be fitted with this assembly element.

Abstract: Assembly element made in a plate of brittle material, such as silicon, in particular for a timepiece, including an aperture provided for the axial insertion of an arbour, the inner wall of the aperture including elastic structures which are etched into the plate and which each include at least one support surface for gripping the arbour radially in order to secure the assembly element relative to the arbour. Each elastic structure is formed by a fork which is connected to the inner wall of the aperture by a bridge of material and which includes two branches extending, on either side of the bridge of material, generally towards the arbour. Each branch includes a support surface in proximity to the free end thereof. The invention also proposes a timepiece fitted with an assembly element of this type.

Abstract: Assembly element (18) made in a plate of brittle material, including an aperture (32) provided for the axial insertion of an arbour (26), the inner wall (33) of the aperture (32) including elastic structures (34), which are etched into the plate to grip the arbour (26) radially. Each elastic structure (34) includes a first rectilinear elastic strip (L1) which extends along a tangential direction relative to the arbour (26). According to the invention, each elastic structure (34) is formed by a radial stack of several parallel elastic strips.

Abstract: The housing (6) of the bearing block (1), locks the peripheral ring (11) of a spring (10) with axial and radial deformation further comprising a substantially annular rigid central support (13) which cooperates with a cap (23), fitted by means of lugs (25) to the outside of the central support (13), to hold the pierced stone (4) and the endstone (5). The resilient part (12) of the spring (10) is for example formed of bent arms.

Abstract: The invention relates to a timepiece which has a resin bearing section. Moreover, the invention relates to a wheel train apparatus which has a resin bearing section. The invention is constituted by the timepiece provided with a gear wheel and supporting members which support the gear wheel, the supporting members being formed from a filler containing resin. Alternatively the invention is constituted by the wheel train apparatus provided with a gear wheel and supporting members which support the gear wheel, the supporting members being formed from a filler containing resin.

Abstract: The invention relates to a timepiece which has a resin substrate, rotors, and wheel trains, and relates to a wheel train apparatus which has a resin substrate, bearing members, gear wheel, and the like. The invention is constituted by a timepiece comprising; a gear wheel, and a substrate which supports a shaft of a rotor and/or a shaft of the gear wheel, the substrate being formed from a filled resin. Alternatively the invention is constituted by a wheel train apparatus comprising: a gear wheel; a substrate which supports one shaft section of the gear wheel, and a bridge which rotatably supports an other shaft section of the gear wheel, the substrate and the bridge being formed from a filled resin.

Abstract: Watch movement comprising a housing (26, 28, 30, 32, 34) and a gear train, formed from a series of spindles (36, 38, 40, 42), pivotably mounted on the housing, of which a first of said spindles (42) is provided with a shank (42a), for fixing a first hand (16) and a second of said spindles (50) is provided with a cylinder (50b), arranged co-axially to said shank, for fixing a second hand (20). According to the invention, the second spindle (50) is rotationally mounted on said housing (34) by means of a ball bearing (54).