EP1700939B1 - Shaft drive for loom shafts - Google Patents

Description

The invention relates to a shaft drive for at least one heald of a loom.

For shedding, a plurality of healds are generally provided on looms, each having a plurality of mutually parallel strands are passed through the thread eyes the warp threads. For shedding the healds are moved up and down very quickly. Serve this shaft drives, which are referred to as dobby or eccentric machines. Eccentric machines generate from the rotating movement of a drive shaft up and Movement of the heald frames, whereby high weaving speeds can be achieved. However, such eccentric machines are inflexible. The creation of patterns or different bindings is limited. Therefore, shaft drives are widely used, in which a pawl clutch is provided between a drive shaft and the eccentric for generating the shaft movement.

Such a dobby is for example from the DE 697 02 039 T2 known. The latching mechanism arranged between the eccentric and the driving shaft is here switched on for each shaft movement, ie for an upward movement of the shaft or for a downward movement of the shaft in each case for half a shaft rotation. Such dobby machines are very flexible. However, it is necessary for the function of the pawl mechanism of such a dobby, that the entire transmission, including all input and output elements and the shaft, during the switching phase stand still. Dobby according to DE 697 02 039 switch in the rest.

On this basis, it is an object of the invention to provide a shaft drive with a ratchet mechanism that allows a high operating speed by this switches in the movement.

This object is achieved with the shaft drive according to claim 1 and according to claim 2:

In the case of the shaft drive, at least one drive pulley that performs a predetermined, for example, uniform rotational movement, belongs to the clutch device. It may be provided a second drive pulley, which is a rotary oscillation movement performs, which is briefly or completely synchronous to the rotational movement of the first drive pulley in selected angular ranges. These short phases of synchronous movement between the two drive pulleys can be used to switch the drive connection to the driven pulley from the first pulley to the second or vice versa. Serve one or more pawls.

The pawl is engaged and disengaged by an actuator. This is e.g. a slider which is adjustable between two positions and past which the pawl, whereby it is actuated according to its position. The actuating device may also be formed by at least one, but preferably two, shifters, past which the pawl passes and thereby actuates, i. e.g. is engaged. For temporary connection of the actuator with the pawl is preferably a link guide. This allows the moving, e.g. with the driven pulley rotating pawl a free movement in the circumferential direction and transmits the directed in the radial direction switching movement to the pawl.

The slide can be actuated by a rotary driven cam, with which it is in contact with a cam follower. The shift levers can be operated directly electrically or pneumatically. However, it is preferred to drive them via a control clutch from a cam drive ago. The control clutch can then be operated with very low power, on the other hand, sufficiently large forces are generated to move the shifter. The clutch can eg via stationary or movable Control magnets are controlled and formed by a swing-driven selection finger. This results in a precisely responsive and with low energy controllable control arrangement for the clutch assembly.

The pawl can be biased by a biasing means to its on or Auskuppelposition out and, if desired, be moved by the actuating device in each case in the off or Einkuppelposition.

A particularly responsive and stable latching mechanism is obtained when the biasing means is a bi-stable device having two stable switching positions. Between these positions, a dead center can be formed. The actuator then has to move the pawl to toggle only over the dead center, after which the pawl switches. This can be ensured even at very high operating speeds, in spite of the impacts acting on the entire mechanism, the resulting vibrations and the centrifugal forces that occur.

It is also considered advantageous to switch the pawl via an actuating device having a slotted guide for the pawl. It suffices if the switching pawl or a cam follower element connected to the pawl engages only in the switching zones, ie those angular ranges of the pawls rotating with the driven pulley, with the link guide in which a switching operation is to be expected. These angular ranges correspond to the upper and the lower dead position of the heald.

The pawl may be constructed in the manner of a rocker and have two switching lugs, one of which is assigned to a first drive pulley and the second of a second drive pulley. Thus, the pawl can serve to selectively produce the drive connection between the first drive pulley and the driven pulley or the second drive pulley and the driven pulley. The pawl can be designed as a rigid rocker, the pivot axis is connected to the driven pulley. In a modification, the rocker may be formed in two parts with a spring-mounted arm.

Furthermore, an embodiment of the invention is considered to be particularly advantageous, in which two mutually separate pawls are provided. Thus, a pawl of the first drive pulley and the second pawl of the second drive pulley be assigned. The pawls are then preferably arranged on diametrically opposite sides of the driven pulley. They may be resiliently biased toward their engaged positions, or may also be connected to a bistable biasing means as described above and with the advantages described above. The embodiment with two pawls has the advantage that the switching movements of a respective pawl can each be determined independently of the switching movement of the other pawl. Again, this is advantageous in terms of reliably achieving high operating and switching speeds.

When the driven pulley is coupled to the first drive pulley, the shaft makes its reciprocating motion. On the other hand, the driven pulley is attached to the second, only by a limited angle back and forth Coupled drive pulley, the shaft is in its resting phase in which he performs only a slight oscillation movement about its upper and lower reversal point. However, out of this oscillation movement, it can be engaged during the short synchronizing phases, with the acceleration forces occurring on the shaft and the gear elements involved and the resulting loads hardly being greater than during uninterrupted operation of the shaft. At least no noticeable sudden changes in the acceleration forces occur.

The oscillating movement of the second drive pulley can be generated by a cam drive or by electrical, hydraulic or pneumatic drives.

Preferably, not only during the phases of movement, but also during the periods of rest of the shaft in which the shaft otherwise rests at the upper or lower point of reversal, does the drive impel continued movement thereof. This opens up the possibility of reducing the maximum acceleration of the shaft. The avoidance of acceleration jumps leads to a smooth running of the shafts, which does not lead to excessive vibrational excitations even at high operating speeds. The limit for the working speed at which shaft fractures and strand breaks occur can thus be shifted very far to higher operating speeds.

Further details of preferred embodiments of the invention will become apparent from the drawings or description and claims.

Figur 1 einen

Webschaft mit mechanischem Schaf- tantrieb in schematisierter Darstellung,

Figur 2 und 3

Zeitverläufe der Schaftbewegung bei unter- schiedlichen Schaftbewegungsverläufen in unterschiedlichen Bewegungsphasen jeweils als Diagramm,

Figur 4

den Schaftantrieb nach Figur 1 in schemati- sierter Darstellung und in Draufsicht,

Figur 5

den Schaftantrieb nach Figur 1 in aus- schnittsweiser, schematisierter Darstel- lung,

Figur 6

den Schaftantrieb nach Figur 1 in aus- schnittsweiser, perspektivischer Darstel- lung seiner Kulissenführung,

Figur 7

den Schaftantrieb nach Figur 5 in einer weiteren schematisierten, ausschnittsweisen Darstellung in einem anderen Maßstab,

Figur 8

den Schaftantrieb nach Figur 1 bis 4 mit Darstellung seiner Schaltklinke mit bista- biler Vorspanneinrichtung, in ausschnitts- weiser Darstellung,

Figur 9

einen Schaftantrieb mit schaltbaren Kurven- scheiben, bistabiler Schaltklinke und Ku- lissenführungen, in schematisierter Dar- stellung,

Figur 10

einen Schaftantrieb mit zwei einnasigen Schaltklinken, in schematisierter Darstel- lung,

Figur 11

den Schaftantrieb nach Figur 10 mit Dar- stellung einer seiner einnasigen Schalt- klinken, in ausschnittsweiser Darstellung,

Figur 12

einen Schaftantrieb mit zwei einnasigen Schaltklinken und Kulissenführungen, in schematisierter Darstellung,

Figur 13

den Schaftantrieb nach Figur 12 mit Dar- stellung seiner bistabilen, einnasigen Schaltklinke, in ausschnittsweiser Darstel- lung, und

Figur 14

einen Schaftantrieb mit zwei einnasigen, bistabilen Schaltklinken nach Figur 13 und Betätigungsschieber, in einer schematisier- ten Darstellung.

In the drawings, embodiments of the invention are illustrated. Show it:

Figure 1 a

Shaft with mechanical Shaft drive in a schematic representation,

FIGS. 2 and 3

Timing of the shaft movement with different shaft movement progressions in different movement phases, each as a diagram,

FIG. 4

the shaft drive after FIG. 1 in a schematic representation and in plan view,

FIG. 5

the shaft drive after FIG. 1 in a detailed, schematic representation,

FIG. 6

the shaft drive after FIG. 1 in a perspective, perspective view of its slotted guide,

FIG. 7

the shaft drive after FIG. 5 in a further schematized, fragmentary representation on a different scale,

FIG. 8

the shaft drive after Figure 1 to 4 with representation of its pawl with bistable pretensioning device, in cut-out view,

FIG. 9

a shaft drive with switchable cam discs, bistable pawl and lissenführungen, in a schematic representation,

FIG. 10

a shaft drive with two single-nose pawls, in a schematic representation,

FIG. 11

the shaft drive after FIG. 10 showing one of its single-nose pawls, in partial view,

FIG. 12

a shaft drive with two single-nose pawls and slide guides, in a schematic representation,

FIG. 13

the shaft drive after FIG. 12 showing its bistable, single-nose ratchet, in partial view, and

FIG. 14

a shaft drive with two single-nose, bistable pawls after FIG. 13 and actuating slide, in a schematic representation.

In FIG. 1 a heald 1 with associated shaft drive 2 is illustrated. The heald 1 is formed by a provided with strands 95 frame, which is in operation as indicated by an arrow 3 moves up and down. To drive a linkage 4, which attaches to the weaving shank 1 at two or more points 5, 6 and forms the output of the shaft drive 2. To the linkage 4 include angle lever 7, 8, which are connected on the one hand with the weaving shank 1 and on the other hand directly or indirectly with the pull and push rod 9. This is connected to the shaft drive 2, the output side of a rocker 11, which follows a pivoting movement has. The shaft drive 2 generates from the uniform rotational movement of an input shaft 12 in FIG. 1 by an arrow 13 illustrated reciprocating motion, wherein this movement on the heald 1 as a largely harmonic oscillatory motion in appearance.

The curve I describes in FIG. 2 the shaft movement of the heald shaft 1 with its X-coordinate (direction of the arrow 3 in FIG FIG. 1 ) over time t. For example, it follows a sine function. As soon as the heald 1 has reached its upper reversal position TO, in which it could, as seen by weaving technology, persist, the curve I changes into a vibration with reduced amplitude and acceleration (curve branch II). The heald 1 thus performs oscillation in a turning point area BTO instead of resting. Near the top of the vertex, the shaft movement changes from curve I to curve II ( FIG. 2 ).

Due to the pendulum movements, the loads on heddle 1 are reduced or largely restricted, because through them the accelerations can be minimized ..

FIG. 3 illustrates that the reverse point oscillation in the rest phase R can be maintained over several cycles.

As FIG. 4 illustrated, a plurality of heald frames 1, 1a, 1b can be arranged at a small distance one behind the other, which are driven by the common shaft drive 2 and thus by the common input shaft 12. This is connected to a rotary drive device 14, which is formed by a servo motor, another electric motor or an output shaft of a central drive device, which drives other organs of the loom.

The said movements of the heald shaft 1 in the movement phases B and the resting phases R are determined by the mechanical shaft drive 2 according to FIG Figure 5 to 7 generated. The shaft drive 2 comprises for each weaving shank 1, 1a, 1b respectively a gear arrangement 15 (15a, 15b) for converting the rotational movement of the input shaft 12 into the reciprocating movement of the respective output side lever 11 (11a, 11b) in the form of a rocker, and a clutch assembly 16 (16a, 16b) via which the transmission assembly 15 is to be selectively connected to or disconnected from the input shaft 12. The clutch assembly 16 and the gear assembly 15 are in the Figures 5 and 7 schematized illustrated. The coupling arrangement serves to control the movement of the heald and is in this respect the mechanically designed here control device C. The structure ( FIG. 7 ) is as follows:

The gear assembly 15 is formed by an eccentric 17 which drives the lever 11 via a connecting rod 18 swinging. The gear assembly 15 thus serves to convert the rotational movement of the eccentric 17 in a reciprocating motion. The clutch assembly 16 includes a first pulley 21 and a second pulley 22 (both referred to as "pulleys" because they form the inputs of the clutch assembly 16). Both discs 21, 22 preferably have the same diameter. However, they can also have different diameters and are designed to improve clarity FIG. 7 also illustrated with different diameters. The first disc 21 is connected to the input shaft 12 and via this to the rotary drive device 14. The disc 21 thus rotates uniformly at a substantially constant speed. This symbolizes in FIG. 7 an arrow 23. The second disc 22 is rotatably supported about the same axis of rotation 24 as the first disc 21. However, it is not constantly rotating but reciprocating, ie driven rotationally oscillating or drehpendelnd. This is illustrated by arrow 25.

To the clutch assembly 16 also includes a switching member 26 in the form of a pawl 27 which is pivotally mounted about a pin 28 on the eccentric 17 (which is also referred to as "driven pulley" because it forms the output of the clutch assembly). The pawl has a first switching lug 29 and a second switching lug 30, wherein the switching lugs 29, 30 are arranged on different sides of the pin 28. The switching lug 29 are assigned to each other by 180 ° opposite recesses 31, 32 in the disc 21. The switching lug 30 are assigned to each other by 180 ° opposite recesses 33, 34 in the disc 22. By a later described Biasing means 35a, the pawl 27 is biased with its switching nose 29 on the disc 21 or away from it.

At its switching nose 30 adjacent end of the pawl 27 is provided with a control roller 35 which is thus biased by the spring of the pawl 27 with respect to the axis of rotation 24 radially outward.

The pawl 27 is eg according to FIG. 6 or 8th designed as a rigid rocker. The movements of the switching lug 29, 30 are then rigidly coupled to each other.

In addition, it may be appropriate to perform the pawl 27 in two parts, as in FIG. 7 is shown. The switching nose 29 carrying arm 27 a and the switching nose 30 supporting arm 27 b can rotate independently of each other about the pin 28. The arm 27b may also be provided with an attachment for the arm 27a. A spring can bias the arm 27a against this projection. As a result, during the synchronous phase, in which the disks 21, 22 run synchronously for a short time, both latching lugs 29, 30 can be engaged. The period in which both detents 29, 30 are engaged can and may be greater due to the pitch of the pawl 27 compared to the one-piece design. By relieving each disengaged switching lug 29, 30, this can then find out at the appropriate moment from its recess 31, 32 or 33, 34.

The pawl 27 are two levers 36, 37 assigned ( FIG. 5 ), each having a for actuating the control roller 35 serving cylindrically curved shift gates 38, 39. The shift gates 38, 39 are approximately concentric to the rotation axis 24 and are each formed by approximately circular arc-shaped grooves (see FIG. 6 ). They have arcuate groove flanks, between which the control roller 35 runs. The shift levers 36, 37 can according to FIG. 5 be pivoted radially inwardly and outwardly about pivot axes 41, 42. The inner pivot position is chosen so that the switching lug 29 of the pawl 27 according to FIG. 8 is lifted out of its respective latching recess 31, 32 when the control roller 35 runs along the outer groove flank of the shift gate 38, 39. Accordingly, the switching nose 30 is engaged in the recess 33, 34. To move the pawl 27 in the opposite direction against the force of the bistable biasing means 35 a, the control roller runs on the inner groove flank of the control link 38, 39.

For actuating the shift levers 36, 37 is a cam drive 43 ( FIG. 5 ), which is connected to the input shaft 12 and, for example, has two cams. This is associated with a trained as an angle lever cam follower lever 44 which actuates the shift lever 36, 37 via a selection finger 45 which serves as a control clutch 46. The selection finger 45 is vertically oscillated by the cam follower lever 44 and thus actuates depending on the pivot position either the free end 47 of the shift lever 36 or the free end 48 of the shift lever 37 by the respective end 47, 48 for the time of the deflection of the cam follower lever 44 is pressed down. In order to adjust the pivoting position of the selection finger 45 as desired, stops 51, 52 are arranged on both sides thereof, which limit the selection finger 45 in its position. The selection finger 45 is attracted and held against the spring force of the compression spring 52B against the stopper 52 by a control magnet 52A, when released for control. Otherwise a compression spring 52 B presses the selection finger 45 against the stop 51 and holds it in position.

While the disc 21 is constantly driven to rotate, the disc 22, as mentioned, driven rotationally oscillating or drehpendelnd. The purpose of a connected to the disc 22 cam follower 53 ( FIG. 5 ), for example in the form of a roller, which is mounted at the end of a rigidly connected to the disc 22 lever. The cam follower 53 is actuated by a cam 54, for example, rotates at twice the speed of the input shaft 12 and has only a single survey. Thus, the disc 22 receives twice per revolution of the input shaft 12 a reciprocating motion.

The shaft drive 2 described so far operates as follows:

It is initially assumed that the eccentric 17 is to rotate constantly. For this purpose, the pawl 27 must constantly connect the disc 21 with the eccentric 17. To achieve this, each of the shift lever 36 and the shift lever 37 must always escape to the outside when the pawl 27 passes as a result of rotation of the disc 21 to the respective shift lever. To this end, the control solenoid 52A is energized so that the select finger 45 pushes the end 47 downward as the pawl 27 passes the shift lever 36 and the select finger 45 pushes the end 48 downward as the pawl 27 passes the shift lever 37.

The buttons 38, 39 of the shift levers 36, 37 extend over an angular range, which serves as a switching range can be viewed. The cam follower 53 forms, together with the cam 54, a pendulum drive 55. This imparts to the disc 22 to a rotary pendulum motion, which is always synchronous with the movement of the disc 21 when the pawl 27 passes through the switching areas. These movement phases are characterized in that the cams of the cam drive 43 urge the end of the cam follower lever 44 to the outside.

During the phase of the synchronous running of the discs 21, 22, the clutch assembly 16 can be switched by the respective shift lever 36 or 37 does not escape to the outside. As a result, for example, the switching lug 29 is pushed out of the latching recess 31 and the switching lug 30 is engaged in the latching recess 33. The relevant shift lever 36 or 37 then remains activated by the relevant shift lever 36, 37, for example by springs 56, 57 (FIG. FIG. 5 ) is held in its inner position and is not moved outwardly by the selection finger 45. The eccentric 17 performs only a reciprocating motion in this state, because he is bound to the disc 22. The movement oscillating back and forth by a few degrees, for example 10 °, causes only a slight upward and downward movement of the same in the upper or lower reversal point of the heald, at most only a few millimeters. This does not disturb the shedding and weaving process. However, it allows a synchronous reconnection, by only the relevant shift lever 36, 37, in which the pawl 27 is, is pivoted outwardly. The cam drive 43 causes this at the moment of synchronization of the two discs 21, 22, so that a soft shock-free restart of the eccentric 17 takes place.

The biasing means 35a biases the pawl 27 into two stable positions. FIG. 8 illustrates an exemplary embodiment. In this case, on one arm of the pawl 27, a push rod 60, which is supported on an abutment 61. This is rotatably and fixedly connected to the bearing of the pin 28 and thus for example attached to the eccentric 17. On the push rod 60 sits a spring 62, for example a compression spring which is supported at one end to the abutment 61 and at its other end to a provided on the push rod 60 disc 63. The push rod 60 is connected to the pawl 27 at a hinge 64. The abutment 61, the joint 64 and the pin 28 are arranged so that the switching rocker 27 and the push rod 60 when passing through a pivoting range of the rocker switch 27 through an extended position. This forms a dead center. On both sides of the pawl has stable Einkuppellagen on. In one, the switching nose 29 is engaged in the recess 31 while in the other stable position, the switching nose 30 is engaged in the recess 33. Thus, the pawl 27 securely retains the coupling position given to it by the control roller 35. The pawl 27 may, as in FIG. 8 and 9 illustrated, rigid or, according to FIG. 7 be formed in two parts. In both cases, it is switched by the switching levers 36, 37 in the respective stable switching positions, which dictates the bistable biasing means 35a.

FIG. 10 illustrates another modification. The illustrated there shaft drive uses pawls 27a, 27b, which, similar to the above-described pawl 27, each with a pin 28a, 28b are pivotally mounted on the eccentric 17. Both pawls 27a, 27b wear each only one switching lug 29, 30. Thus, the pawl 27a of the disc 21 and the pawl 27b of the disc 22 is assigned. The peel pawls 27a, 27b are by springs, such as the FIG. 11 apparent wrap spring 35b biased toward their latching position. The pawl 27a is engaged with the disk 21. The pawl 27b is disengaged from the disc 22. To disengage the pawls 27a, 27b serve the shift lever 36, 37 and their preferably cylindrically curved buttons 38a, 39a, the shift gates 38, 39 of the switching device according to FIG. 6 replace.

The embodiment with separate pawls 27a, 27b allows the engagement of the respective desired pawl 27a or 27b, regardless of how quickly the other pawl reaches the disengaging position.

As FIG. 12 illustrated, the pawls 27a, 27b can be actuated via shift gates 38, 39. For this purpose, the pawls 27a, 27b according to FIG. 11 as well as pawls according to FIG. 13 Find application. In addition, the pawls 27a, 27b, as shown in FIG FIG. 10 illustrated, in the same sense of direction. The pawls 27a, 27b according to FIG. 13 are each provided with a bistable biasing means 35a, as already associated with FIG. 8 has been described. The too FIG. 8 Applicable description applies accordingly.

The pawls 27a, 27b can be actuated both by the switching levers 36, 37 and by a slide 65 on which the two links 38, 39 are formed. The slider 65, for example, slidably mounted with respect to the axis of rotation 24 in a selected radial direction be and how FIG. 14 illustrated by a control cam 66 are actuated. The slider 65 guarantees a synchronous switching of the two pawls 27a, 27b, so that even at high switching speeds faulty circuits are avoided.

Furthermore, the slider 65 may be associated with a holding magnet 67 in order to hold the slider 65 in an end position.

A novel shaft gearbox allows the switching on and off of individual heald frames, even at high working speeds. For this purpose, pawls are provided which couple an eccentric with permanently rotating and / or reciprocating sheaves. Measures to improve the controllability of such a clutch assembly are each for themselves control of the pawls on shift gates, assignment of bistable biasing means to the pawls and / or distribution of the switching function on individual pawls 27a, 27b, each of which different discs 21, 22 are assigned individually. Preferably, one of the two discs performs a continuous rotational movement and the other disc only a pendulum movement, which dictates the shaft movement during the sheep rest phases.

LIST OF REFERENCE NUMBERS

1, 1a, 1b

heald

95

braid

2

shaft drive

3

arrow

4

Downforce (e.g., linkage)

5, 6

Put

7, 8

bell crank

9

Pull and push rod

11

wing

12

input shaft

13

arrow

14

Drehantreibseinrichtung

15

transmission assembly

16

clutch assembly

17

eccentric

18

pleuel

21, 22

Input element / disc

23

arrow

24

axis of rotation

25

arrow

26

switching element

27

ratchet

27a, 27b of the disc

21, 22 associated ratchet arm

28

spigot

29, 30

switching tabs

31, 32, 33, 34

recesses

35

control roller

35a

biasing means

35b

wrap

36, 37

gear lever

38, 39

shift gate

38a, 39a

button

41, 42

swivel axis

43

cam drive

44

Cam follower lever

45

selection finger

46

control clutch

47, 48

The End

51, 52

control magnets

52a

control solenoid

52b

compression spring

53

cam follower

54

cam

55

pendulum drive

56, 57

feathers

60

pushrod

61

abutment

62

feather

63

disc

64

joint

65

pusher

66

control cam

67

holding magnet

B.

movement phases

C

control device

T0, TU

Reverse position, reversal point

BTO

Reversal point range

t

Time

R

dormancy

S

synchronous phase

Claims (21)

1. Heald frame drive for at least one heald frame (1) of a weaving machine,
   with at least one output (4), which is associated with the heald frame (1) and connected thereto in order to hold this in resting phases (R) and to impart a movement in movement phases (B),
   with a control means (C) to control the current speed of the output (4) and thus that of the heald frame (1),
   with a coupling arrangement (16), which belongs to the drive (2) and is arranged between a drive means (14) and a gear arrangement (15) for transmitting the drive movement to the heald frame (1),
   wherein the coupling arrangement (16) has a first driving wheel (21) connected to the drive arrangement (14) and a second driving wheel (22) as well as a driven wheel (17), which is selectively connected to the first or the second driving wheel (21, 22) by means of at least one pawl (27),
   wherein the pawl (27) is held by a bistable prestressing means (35a) to be movable back and forth between two stable positions.
2. Heald frame drive for at least one heald frame (1) of a weaving machine,
   with at least one output (4), which is associated with the heald frame (1) and connected thereto in order to hold this in resting phases (R) and to impart a movement in movement phases (B),
   with a control means (C) to control the current speed of the output (4) and thus that of the heald frame (1),
   with a coupling arrangement (16), which belongs to the drive (2) and is arranged between a drive means (14) and a gear arrangement (15) for transmitting the drive movement to the heald frame (1),
   wherein the coupling arrangement (16) has a first driving wheel (21) connected to the drive arrangement (14) and a second driving wheel (22) as well as a driven wheel (17), which is to be selectively connected to the first or the second driving wheel (21, 22) by means of a first pawl (27) or a second pawl (27a) spaced therefrom.
3. Heald frame drive according to claim 2, characterised in that the pawl (27) is held under prestress towards a stable position by a prestressing means (35a).
4. Heald frame drive according to claim 2, characterised in that the pawl (27) is held by a bistable prestressing means (35a) to be movable back and forth between two stable positions.
5. Heald frame drive according to claim 1 or 2, characterised in that the pawl (27) is movable back and forth between an engaging position and a disengaging position by an actuating element (36, 65) with a connecting link guide (38).
6. Heald frame drive according to claim 5, characterised in that the connecting link guide (38) engages with the pawl (27) only in selected rotational positions of the drive means (14).
7. Heald frame drive according to claim 5, characterised in that the actuating element (65) is an actuating slide.
8. Heald frame drive according to claim 1 or 2, characterised in that the drive means (14) imparts a movement with a constant direction of movement to the first driving wheel (21) and wherein a movement with varying directions is impressed on the second driving wheel (22).
9. Heald frame drive according to claim 1 or 2, characterised in that the output (4) also performs a predetermined movement during the resting phases (R).
10. Heald frame drive according to claim 1 or 2, characterised in that the predetermined movement of the resting phases (R) is determined by the control means (C).
11. Heald frame drive according to claim 1 or 2, characterised in that the acceleration of the output (4) at the beginning of a resting phase (R) is the same as its acceleration at the end of the preceding movement phase (B).
12. Heald frame drive according to claim 1 or 2, characterised in that the acceleration of the output (4) at the beginning of a movement phase (B) is the same as its acceleration at the end of the preceding resting phase (R).
13. Heald frame drive according to claim 1 or 2, characterised in that the output (4) performs an oscillating movement during the resting phases (R).
14. Heald frame drive according to claim 1 or 2, characterised in that the first driving wheel (21) and the second driving wheel (22) are driven synchronously at least for a short period, and that the switchover of the coupling arrangement (16) is performed during the synchronous phase.
15. Heald frame drive according to claim 1 or 2, characterised in that the second driving wheel (22) is connected to a pendulum drive (55), which imparts an oscillating movement to the second driving wheel (22).
16. Heald frame drive according to claim 1 or 2, characterised in that the pawl (27) is to be permanently connected to the cam (17) and selectively connected to the first or the second driving wheel (21, 22).
17. Heald frame drive according to claim 15, characterised in that the rotational-oscillatory movement of the second driving wheel (22) is synchronous to the rotational movement of the first input element (21) at switching positions predetermined by the actuating element (36, 37).
18. Heald frame drive according to claim 5, characterised in that the actuating element (36, 37) is formed by at least one control lever (36, 37), which is associated with the pawl (27) in order to engage or disengage this in at least one predetermined switching position.
19. Heald frame drive according to claim 1 or 2, characterised in that the pawl (27) is connected to the driven wheel (17) and rotates with this.
20. Heald frame drive according to claim 19, characterised in that the actuating element (36, 37) is connected to a cam drive (43) by means of a control coupling (46).
21. Heald frame drive according to claim 20, characterised in that the control coupling (46) has a selection finger (45), which is disposed to be adjustable between at least two positions in order to activate and deactivate the actuation of the control lever (36, 37) through the cam drive (43), and that the selection finger (45) is movable by means of a combination of control magnet (52A) and pressure spring (52B).

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