FR2697853A1 - Method and device for decoupling the gripper drive on gripper looms. - Google Patents

Abstract

Device for decoupling the gripper drive on gripper looms and its implementation method, characterized in that each gripper element (6) corresponds to a coupling device (3, 3' , 3") by shape, which can be switched in a manner known per se, in the sector between the output shaft (23) of the gear (2) and the gripper element (6) considered, to correct the position of the gear (2), in the area of the form coupling device (3, 3', 3"), a controllable corrector member (41, 44) is provided on each clamp rod (6) corresponds, for the purpose of its fixation in the decoupled position, to an immovable blocking device (5, 5'), which can be controlled.

Description

The invention relates to a method for decoupling the gripper drive.

  on looms with pliers, made up of elements forming pliers movable in the crowd, comprising a gear, for the elements forming pliers, driven in an oscillating manner by a

  changing drive, including a coupling device

  which can be engaged in the gear sector

  swimming, comprising an output wheel per gripper element and comprising devices for feeding the weft threads from one side of the loom, in which, in each weaving cycle, the weft thread is placed in front the gripper elements to be driven, and the gripper elements are freely released from their coupling by shape with their drive, and are locked in a position outside the pitch of

chain, in coupling position.

  The invention also relates to a device for implementing the method, in particular on

  double sided carpet looms.

  DE-PS 21 62 786 discloses a process in which, for the purpose of manufacturing double-sided velvet fabrics, on double-sided carpet looms, with two shuttles, it is inserted in alternation which can be ordered, in two levels of overlapping crowds, either simultaneously each time a frame, or successively, in irregular alternation, each

  times a single frame from one of the crowds.

  The insertion at will of a weft is controlled by the fact that according to a program, a weft thread is engaged or not engaged on the insertion element

  wefts, for example on the rod forming pliers.

  In each cycle, the insertion organs of the

  weft threads are moved in the independent warp

part of the program.

  A form of drive of this type, which has also been described in a comparable manner in DE-OS 21 64 948, has drawbacks, since the drive energy for acceleration or deceleration of the organs of insertion of frames must be developed,

whether the frame is inserted or not.

  Another disadvantage lies in the fact that, in the case of the elimination of a broken weft, the pliers rod must be blocked in the crowd, during its engagement movement, by additional means of decoupling, although the elements forming the crowd and

  the leaf must carry out their lifting movements.

  This requires a complex technique.

  To simplify this situation, DE-PS 37 31 990 and DE-PS 38 26 156 each propose a design of

particular coupling.

  The coupling devices shown are arranged in the gear sector, between a rack segment driven in an oscillating movement and the output wheel in question, to form a rod forming a clamp. The examples show the coupling device on the axis of the gear wheel, which meshes with the

segment.

  This coupling device constitutes the assembly

  shape blocking between a driven shaft and one of the

cogwheels of the gear.

  This switching-capable coupling device can, in principle, also be used on the output shaft of the gear, where it would constitute the coupling

  by shape between output wheel and output shaft.

  On weaving looms with two steps

  superimposed chain and two rods forming superpo- clips

  gears of this type have two output wheels. According to the example of DE-PS 37 31 900, each of these output wheels can have a coupling device, which should of course be placed on

their axes.

  A design of this type of the gear with the aforementioned coupling devices, is capable of operating in a safe manner, when all the gear wheels and the sets of bearings of the gear, are

  formed almost without play, from the drive curve

  up to the rack of the pliers rod.

  As a general rule, this can only be achieved when a new machine is assembled, and even then,

  only in exceptional cases.

  Due to the large number of gear elements and the extremely high transmission of the lifting of the cam disc, up to the displacement of the rod forming

  pliers, extremely high tolerances may occur

  grate in the lifting of the pliers rod.

  As a result, a device designed in this way is hardly usable in industry. The device

  of coupling which can be switched, by shape, cannot

  cannot be reliably paired.

  Another major drawback is the

design of the coupling itself.

  The two last mentioned patents possess-

  tooth as movable coupling elements, each an axially movable bushing, with coupling elements, and each a gear, which is constantly

  in engagement with the segment or with another toothed wheel.

  For switching purposes of the delivery device

  this socket is offset axially by

electro-mechanical means.

  This movable switching member requires considerable forces to be offset, within the time available, which must be developed either by oversized magnets or by a motor provided with a gear motor. Coupling devices with masses at this high point cannot be used for decoupling and coupling the drive from the

  pliers rod during the normal weaving process.

  On the other hand, said coupling devices lead, due to their high masses, participating in the drive movement of the rods forming grippers, to a considerable increase in the inertial forces as a whole, and thus to a reduction in the speed of rotation of the machine. Due to these drawbacks, controlled insertion has hitherto been used in practice

  of the frame to control the insertion of frame at will.

  A weft thread was presented or not at the head of the clamp moving in the weft pitch, at each cycle

weaving.

  The disadvantages of this method of procedure have already

  were explained during the assessment of DE-PS 21 62 786.

  The object of the invention is to make the process given in DE-PS 21 62 786 usable on looms of double-sided carpets, with elements forming pliers, arranged in pairs, which can be decoupled.

during the weaving process.

  The coupling device must be placed in the gear in front of the gripper element considered

  and configured to allow an operating mode

  reliability of the device in the time available up to the stop of the weft thread and in the formation of a new shed, while maintaining the machine rotation speeds

usual.

  According to the invention, a method is first proposed, with the aid of which it is possible to position, each time, in the normal weaving cycle, both the rods forming decoupled pliers and the gear in the

  area of the controlled coupling, so that the elements

  Coupling elements by shape can be decoupled and coupled, according to the shortest trajectory and in the shortest time, according to high reliability and precision. The device which makes it possible to implement the method comprises: a) in correspondence with each gripper element, a coupling device by shape, which can be switched in a manner known per se, in the sector comprised between the shaft of output of the gear and of the gripper element considered, b) to correct the position of the gear, in the sector of the coupling device by shape, a correcting member which can be controlled and, c) in correspondence with each rod forming a clamp, for the purpose of fixing it in the decoupled position, a

  stationary locking device, controllable.

  This device makes it possible to arrange the coupling in the sectors of the greatest trajectories and thus it works in a reliable way in the sector of the forces

the weakest.

  The embodiment of the coupling device comprises: a) coupling devices by shape which can be switched, disposed each time between the shaft

  gear output wheel and the corresponding output wheel

  dante, b) a coupling device consisting of a switching member per output wheel which can be offset in the axial direction relative to the output shaft, coupled by shape in the direction of rotation by means of a torsion safety device with the output shaft, and having axial coupling projections, which can be inserted into axial recesses of

the output wheel considered.

  This embodiment can be completed on a double-sided carpet loom, with relatively limited technical means, since it is not necessary to modify the rod guide elements.

forming clamps.

  The advantage in particular compared to DE-PS 38 26 156 and 37 31 990 lies in the fact that the mass of the parts, which must be movable in the direction

  of the coupling device, is kept very small.

  On the other hand, the parts which must be movable in the direction of the drive of the gripper rods are also limited to a size as small as possible. The inertia forces during acceleration and deceleration of the gripper rods are thus kept within acceptable limits, so that it is practically possible, for these reasons, to exclude

  rotational speed reductions.

  The configuration of the coupling device is such that a) the switching member of the two coupling devices, which can be offset in the axial direction and is integral in driving the output shaft, is disposed between the two output wheels , b) then the switching members of the two coupling devices, which can be offset in the axial direction and integral in driving the output shaft, are fixedly coupled with each other and the member switching alone can be coupled by a single switching means alternating with one of the

output wheels.

  This configuration is particularly suitable when, on double-sided carpet looms, one has to work with a single shuttle on two superimposed chain pitches In this case, a weft is inserted each time in the upper crowd, then a weft in

  the lower crowd, alternating regularly.

  The invention is not limited to the application to a

precise gripper element.

  However, it can be applied, with a particular advantage, to carpet looms

  double-sided, comprising rods forming rigid pliers.

  In a first embodiment, a) the switchable coupling device is arranged between the toothed profiles of the clamp element and the toothed profile of the output wheels and b) the toothed profiles of the two elements can be coupled by a movement of these one relative

to the other.

  In this embodiment, the relative lifting of the coupling device between the driving and driven elements is carried out, between the teeth of the output wheel and the teeth of the clamp rod, no additional active mass must be actuated in meaning

  for driving the rods forming pliers.

  The number of elements to be moved in the direction of the coupling device is limited at this location to a minimum, and can be further reduced significantly by the configuration of the device in which: a) the member, carrying the toothed profile of the element

  forming a clamp, is movable according to switching, perpendicular to

  in relation to the axis of the output wheel, b) the clamp element is coupled with a rack and the output wheels can be offset along the toothed profiles parallel to the direction of the axis of the wheel output according to switching

one in relation to the other.

  c) the usual lateral limitation, known per se of the rack, is hollowed out at least on one side in

  the area of action of the coupling device.

  d) the rack is made up of two parts, and the section coming into engagement in the coupling sector of the rack is movable near the head of

  clamp, relative to the output wheel.

  The device may have: a) near the crowd entry opening, switching position stable control elements corresponding to the toothed part of the clamp element, b) a cam disc device , acting by shape, as a drive means for the gear, the lift curve of which has low values

  acceleration in the coupling sector (E).

  The above refers to the art and the manner

  to control the coupling elements and to configure

  tion of the drive curve in the coupling sector, and contributes considerably to

  ensure a significant succession of frame insertions.

  The arrangement of a so-called correction element for the synchronization of the gear changing in the final position or of coupling, is transposed in a judicious manner where it is possible to obtain with a reduced drive lift, a positioning sufficiently precise, relative to each other, of the rod forming

  clamp and the output member of the gear.

  Experience has shown that this corrective element must be positioned, judiciously, in the sector of the first or second gear level,

after the toothed segment.

  Typically, the game in the gear section

  next stroke is only of such importance that the position differences in the coupling sector by

  shape can be compensated for by

beach rounded against each other.

  This coupling embodiment according to the invention, in association with the aforementioned method, allows, at high speeds of rotation of the loom, optimal weft insertion methods, for a large succession of weft insertion, for reliability.

  high working life

  lants. Various other features of the invention

  appear moreover from the detailed description which

follows.

  Embodiments of the object of the invention

  tion are shown, by way of nonlimiting examples,

to the accompanying drawings.

  Fig 1 shows a schematic overview of the pliers rod drive of a loom, with two superimposed chain pitches and rods

forming corresponding pliers.

  Fig 2 shows a schematic sectional view with coupling devices that can

  be switched, corresponding to the two drive wheels.

  Fig 3 shows a representation similar to the

  fig 2, with a coupling device for the

  alternating output wheels in the drive.

  Fig 4 shows a schematic representation of the correcting element, for the position of the gear

in the switching phase.

  Fig 5 shows a second embodiment

relative to fig 4.

  Fig. 6 shows a schematic representation of the rod-forming pliers drive, with a device

  lifting for the pliers rod.

  Fig 7 shows a representation similar to that of Fig 6, with a lifting device for a

intermediate wheel.

  FIG. 8 shows a representation of the rod forming a clamp offset by 90 relative to FIG. 6,

  with a shift device for the output wheel.

  Fig 9 shows a representation similar to that of Fig 6, with a divided rack and a switching device for the rack section

can be lifted.

  Fig 10 shows a representation similar to that of Fig 8, with a divided rack and an offset device for the rack section

can be offset.

  Fig 11 shows a detail of a trajectory / time diagram of the terminal level of the gear in

  the coupling sector, outside the chain pitch.

  The weaving loom is designed in a manner known per se, to drive pliers rods 6 with a changing drive 1, which transmits by shape from cam discs 11 a changing movement to the blade 12 and from there to toothed segment 13, via

a connecting rod.

  A gear 2 multiplies the changing movement of the segment 13 and transmits it, with the output wheels 231, 232, respectively to the racks 61 or 61 'of the pliers rods 6, 6' The gear 2 has a drive wheel 21, which meshes with the segment 13. The output shaft 23, on which the output wheels 231 and 232 are first of all supported in free rotation is driven by a first and a second

transmission levels 22.

  Between the output shaft 23 and the output wheels are arranged each time coupling devices 3, 3 ', which can be coupled as desired with the output shaft, using a switching member 31 , 31 ', one

  switching lever 33, 33 ', under the action of a drive

switching operation 34, 34 '.

  By means of a torsion safety device 32 ′, the switching member 31, 31 ′ is connected, by shape, in the direction of rotation to the output shaft 23 and is movable in the axial direction, on the tree of

exit 23.

  FIG. 3 shows a second variant of these coupling devices. In this variant, it is a question of distributing the warp threads in a manner known per se, in two small masses 9, 9 ′, vertical, superimposed, on the craft that makes armor of

frame.

  It is then inserted alternately each time a frame in the upper crowd 9 and then a frame

in the lower crowd 9 '.

  The pliers rod 6.6 ', the use of which is not necessary each time, is decoupled from its drive, outside of the chain pitch 9, 9', is blocked at this location and is again coupled, during from the next weaving cycle, to the drive and the blockage released. To achieve this weft weave, it is not necessary to control the coupling device 3.3 ′ of each output wheel 231, 232, by pulses

of program.

  Regular switching every two successive weaving cycles is sufficient This switching operation can be carried out by cam discs and elements

  correspondingly installed.

  In this particular case, the coupling consists for the two output wheels 231, 232, of a single switching member 31 ", of a single switching lever

  33 "and a single 34" switching drive.

  The switching member 31 "has corresponding claws at both ends which can be engaged

  according to a precise position, with corresponding claws

  Dantes of the output wheels 231, 232 In the high position, the switching member performs the drive assembly with respect to the output wheel 231 and in the low position, with respect to the output wheel 232.

  In order to ensure, during each switching cycle,

  tion, that the position of the gear with the considered position of the pliers rod, are placed

  precisely one with respect to the other, in particular

  link during coupling, a gear known as corrector 4 is

assigned to gear 2.

  The corrective gear serves to bring the gear into a precisely defined position with respect to the

  rod forming clamp, before decoupling.

  In the next step, the clamp rod 6, 6 'is locked each time by a blocking device 5 in the position reached, and then the coupling between the gear and the clamp rod, is opened or

  closed when scheduled.

  Decoupled, the rack 61, 61 ', of the clamp-forming rod 6, 6', remains thus during the next cycle of insertion of the weft, in this locked position The coupled rack is released by the

blocking 5.

  Once the weft insertion operation is complete, the gripper rod 6 again reaches its

  initial position outside the chain pitch.

  The gear 2 and the changing gear 1 have a large number of elements which, when they cooperate, produce a play or are elastic in themselves This play, like the overall lifting, is transmitted to a large extent

with differences.

  It follows from this, in particular in the outlet sector, where the coupling device, by shape, which can be switched, is arranged, that it is practically impossible to reach an exact position, at the end points of the lifted There is a high probability

  to see the coupling by shape not mesh.

  This condition could be compensated for by designing the claws of the coupling device 3, 3 'with large insertion chamfers.

  of this type, however, require considerable lifting-

  larger for the switching members, which cannot be traversed, in the case of the gear masses and the masses of the switching members,

  in the necessarily short period of time.

  The use of coupling devices of this type ultimately leads to insertion performance of

  reduced weft and does not exclude the probability of failure

  spears, caused by the coupling operation.

  To this end, a corrective gear 4 is provided in the end sector of the gear, judiciously on the wheel ensuring the drive of the second level of transmission. Two correcting gears 4 of this type are

  shown schematically in Figs 4 and 5.

  In FIG. 4, the toothed wheel 221 comprises a pivot 42 near its outer periphery. A corrector member 41, fixed on a slider 45, which can be offset in the radial direction, has a head comprising chamfers of introduction in the form of funnel, which end in a blocking zone During the last rotation of the toothed wheel 221, this member

  corrector 41 is approached the displacement trajectory

  ment of the pivot 42, and by another radial displacement of the corrector member 41, the pivot 42 is held in a

precise position.

  By a particular configuration of the funnel-shaped introduction curves, the toothed wheel 221 does not need to undergo an additional displacement,

  when stopped, when one of the chamfers

  tion stops the toothed wheel 221 and the other prevents the

  going back, during its radial displacement.

  The corrector device shown in FIG. 5, with its corrector member 43 acts in a similar manner on the toothed wheel, and with the pivot 44 on the slider 45. A cam disc, which is engaged, can be used as corrector drive. to be driven with the main shaft (not shown), or a servomotor

  separate, with rack, as shown in fig 1.

  The principle of the blocking device described here can be applied to all coupling operations,

  regardless of the design of the coupling devices

  is lying. In fig 6 to 10 different modes are represented

  decoupling rods forming clamps 6, 6 '.

  FIG. 6 shows how the assembly of the device for guiding the rod forming a gripper is offset in such a way, perpendicular to the direction of driving the rod forming a gripper 6, that the teeth of the rack 61 are lifted out of the output wheel 231 This variant has some drawbacks, since the gripper guide device must meet high requirements from the point of view of its precision. The lifting elements 356 necessarily bring additional tolerances and threaten

  thus the precise insertion of the frame.

  The embodiment according to FIG. 7 keeps the rigid guide of the clamp-forming rod 6 and rotates an intermediate wheel 24, which meshes with the output wheel 231 guided on a lever 25, outside or in the

  rod sector forming a clamp 61.

  Given the presence of the intermediate wheel,

  here we must take into account additional inertial forces

  in the direction of drive of the cremail-

1st 61.

  The embodiment according to FIG. 8 avoids the intermediate wheel, between the rod forming a clamp 6 rigidly guided and the output wheel 231 Here, the output wheel 231 is raised laterally out of the profile of the

  rack 61, for removable coupling Natural-

  Lement, it is necessary for this purpose that, in this coupling sector, one of the walls of the guide profile of the

rack 62 is hollowed out.

  Figs 9 and 10 show examples of arrangements

  coupling devices, in which the rack 61 of the pliers rod 6 is designed divided The small section 612 of the racks 61, which meshes with the output wheel 231, in the coupling position, is lifted from the teeth of the output wheel 231, in fig 9 and laterally offset outside the profile of the teeth of the

output wheel, in fig 10.

  In particular, in the last two variants, it is wise not to expose the meshing teeth, during the following operation of acceleration of the rod

  forming a clamp at an extremely high load.

  For this purpose, the curve 11 of the changing gear 1 is provided before entering the maximum acceleration phase with a section of curve E (fig 11), which in the case of low acceleration values, leaves the teeth acting during the coupling phase, outside the coupling sector. In principle, the high reliability of the device shown here can be obtained by the following process steps, depending on an operating capacity.

and high reliability.

  We can follow the different process steps on the path-time diagram, of the rod forming

pliers, described in fig 11.

  Once weft insertion is complete, the upper

  forming clamp 6 returns by following the path 81.

  Gear 2 can take positions 81 'and 81 ", at

  its last level due to the existing game.

  In the final phase of the displacement, the corrective gear 4 performs the first phase of process A, that is to say the adjustment of the gear elements in

  the sector of the last level, on a position of consi-

gne.

  During the second step B, the one or two rods forming clamps 6, 6 'are fixed by the locking device 5, 5' and held in the set position. Next, the coupling step C takes place, which is controlled by a programmed command or a cam disc device. The rack 61 is either disconnected from the output wheel 231, 232, or from the output shaft.

23, or coupled with it.

  In the opposite direction to this coupling operation C, the blocking of the clamp-forming rods 6, 6 ′ is lifted or maintained, during a last step D. During a next step E, the meshing teeth are distant from each other between the rack 61 and the output wheel 231, 232, at

reduced rotation speeds.

  When this is done, the clamp-forming rod 6, 6 ′ is driven with maximum acceleration, to

weft insertion.

  In the next cycle, this process is repeated.

  A pliers rod 6, 6 ', which has not worked so far, remains locked in the position in which the gear 2 is fixed in the corrected position, during

  the next working lift of the pliers rod 6.

Claims (14)

  1 Method for decoupling the gripper drive on gripper looms, comprising gripper elements movable in the crowd, comprising a gear driven in an oscillating manner by a changing drive, for the gripper elements, with a coupling capable of be switched in the sector of the gear wheel of the gear, comprising one output wheel per gripper element and comprising devices for feeding the weft threads from one side of the loom, in which, in each cycle of weaving, the weft yarn is placed in front of the clamping elements, for training purposes and   the gripper elements are released as desired   tee of their coupling by shape with their drive, and are locked in a position, outside the chain pitch, in coupling position, characterized in that, during a first step (A), the gear (2 ) is brought into a stable coupling position (83) in the final position of the gripper elements (6) outside the chain pitch (9) inside the gear set in that the element forming clamp (6) is blocked (B) the coupling by shape (3.3 ') is switched (C) and before the new lifting for weft insertion the blocking of the elements forming clamps (6) is released in the opposite direction of switching the   coupling device (3, 3 ') (D).   2 Method according to claim 1, characterized in that, when applied to weaving looms   with two elements forming clamps (6) corresponding   adjacent to chain steps (9, 9 '), superimposed, each clamp member (6) is coupled and   blocked independently of the other clamp element.   3 Device for implementing the method according to   one of claims 1 and 2 on weaving looms   with grippers, with two gripper elements, adjacent to each other, driven, with toothed profile, with a gear for the two gripper elements and each with an output wheel on the output shaft of the gear for each gripper element, characterized in that, to each gripper element (6) corresponds a coupling device (3, 3 ', 3 ") by shape, which can be switched in a manner known per se, in the sector between the output shaft (23) of the gear (2) and of the gripper element (6) considered,   in that to correct the position of the gear   swimming (2), in the sector of the coupling device by form (3, 3 ', 3 "), a correcting member (41, 44) which can be controlled is provided and in that at each rod forming a clamp (6 ) corresponds, for the purpose of fixing it in the decoupled position, to a stationary locking device (5, 5 ′), can be ordered.   4 Device according to claims 3, character-   rised in that, the formable coupling devices (3, 3 ', 3 ") which can be switched, are arranged each time between the output shaft (23) of the gear (2) and the output wheel (231, 232) corresponding, in that the coupling device (3, 3 ', 3 ") consists of a switching member (31, 31', 31") by output wheel (231, 232) which can be offset in the axial direction with respect to the output shaft (23) and is formally coupled in the direction of rotation via a torsion safety device (32) with the output shaft ( 23), and has axial coupling projections, which can be inserted into axial recesses of the   output wheel (231, 232) considered.   Device according to one of claims 3 and   4, characterized in that the switching member (31, 31 ', 31 ") of the two coupling devices (3, 3') can be offset in the axial direction and secured in driving the output shaft ( 23), is arranged between   the two output wheels (231, 232).   6 Device according to one of claims 3 to   , characterized in that the switching members (31, 31 ') of the two coupling devices which can be offset in the axial direction, and which are integral with the output shaft (23), are fixedly coupled to the one with the other and in that the switching member (31 ") alone can be coupled by a single switching means (34) alternating with one of the output wheels (231, 232).   7 Device according to claim 3, character-   laughed at in that there is provided, as a gripper element, each time a gripper rod (6), known in   itself, with profile forming a rack (61).   8 Device according to claim 3, character-   risé in that the coupling device (3, 3 ') which can be switched is disposed between the toothed profiles (61) of the clamp element (6) and the toothed profile of the output wheels (231, 232) and the toothed profiles of the two elements (61, 231, 232) can be coupled by a movement of these relative to each other.   9 Device according to claim 8, character-   that the output wheel (231, 232) is configured   designed as an intermediate wheel (24), the axis of which is   movable according to switching, in a bearing, perpendicular to   relatively to the toothed profile of the forming element clamp (6).   Device according to claim 8, character-   risé in that the member carrying the toothed profile (61) of the clamp member (6) is movable according to switching, perpendicularly to the axis of the wheel exit (231, 232).   11 Device according to claims 8, charac-   terized in that the clamp element (6) is coupled with a rack (61) and the output wheels (231, 232) can be offset along the toothed profiles parallel to the direction of the axis of the wheel output (231, 232) according to switching relative to each other.   12 Device according to claim 11, charac-   terized in that the usual lateral limitation, known per se of the rack (61), is hollowed out at least   on the one hand in the sector of action of the delivery system plement.   13 Device according to one of claims 7 to   12, characterized in that the rack (61) is constituted   killed in two parts, in that the section (611, 612)   engaging in the racking coupling sector-   lère (61) is movable near the gripper head, by   relative to the output wheel (231, 232).   14 Device according to one of claims 7 to   13, characterized in that near the crowd entrance opening, control elements (356, 357,   358, 359, 350) stable position, switching, corres-   lay on the toothed part (61, 611, 612) of the element forming a clamp (6).   Device according to one of claims 3 to   14, characterized in that a cam disc device (11), acting by shape, is provided as a means of driving the gear, the lift curve of which has low acceleration values in the sector coupling (E).   16 Device according to one of claims 3 to   , characterized in that a pair of abutment surfaces (42, 43) is provided on the front side on a toothed wheel (221) of the gear (2) at a distance from the axis of rotation of the latter, to which correspond the elements   correctors (41, 44) which can be ordered.   17 Device according to one of claims 3 to   16, characterized in that the correcting elements (41, 44) which can be controlled have a cursor (45) capable of translation, substantially in the radial direction, relative to the toothed wheel towards the abutment surfaces, and in that the abutment surfaces and the slider (45) cooperate by means of curves arranged in the form of a wedge, the toothed wheel (221) being almost fixed by shape in the center of the set of elastic gears,   when the cursor (45) is in the internal position.