EP0210183B1 - Open-end spinning machine with a plurality of spinning points, whose spinning elements are driven jointly by a combined drive - Google Patents

Abstract

An open-end spinning machine in which a combined drive (56) is provided for the point driving of spinning elements (1) of a plurality of spinning points (S) arranged next to one another. At the spinning point (S) a switching device (2) is provided, by means of which this spinning point (S) can be switched over to a stationary ancillary drive (57). The combined drive (56) has a main drive belt (5) for the joint driving of this plurality of spinning elements (1), as well as an ancillary drive belt (53) driven at a second speed for the individual driving of a spinning assembly (1). By means of the switching device (2) the main drive belt (5) or the ancillary drive belt (53) can be used as a drive for the spinning assembly (1). The thread joining is effected at a rotor speed in the vicinity of the production rotor speed.

Description

The present invention relates to an open-end spinning machine with a plurality of spinning stations arranged side by side, the spinning elements of which are driven together by a collective drive.

It is known to carry out the piecing process at a reduced rotor speed, the speeds of fiber feed and thread take-off being adapted to this reduced rotor speed in such a way that the rotor speed ratio between the individual spinning elements, which is predetermined for spinning production, is always maintained (DE-OS 2 058 604). In order to achieve this reduced rotor speed for the spinning of a single spinning position in a large number of jointly driven spinning positions in a simple manner, the speed of the spinning rotor is scanned for production speed during the run-up and the piecing process is initiated when the reduced speed is reached (DE-AS 2 341 528 and DE-OS 2 610 575). However, the time available here and the rotor speed are not constant and vary in particular depending on the running state of the machine and the individual rotor bearings. This affects not only the piecing success but also the speed and quality of the piecing.

It is also known to provide a transmission gear with two predetermined transmission ratios for each spinning position between a drive belt and the rotor shaft, which alternately take over the drive of the spinning rotor for piecing or for production (DE-OS 2 754 785, JP-PS- AS 21 966/84). As a result, there is a percentage reduction in the piecing rotor speed, but this is always in a fixed ratio to the production rotor speed. The piecing speed is therefore different depending on the production rotor speed.

The invention is based on the surprising finding that the rotor speed for the attachment process should not always be the same low and should not always be reduced in a fixed ratio to the production rotor speed. The correct rotor spinning speed depends on the fiber material to be spun.

The purpose of the present invention is therefore to avoid the disadvantages indicated above. In particular, it is an object of the invention to provide a simple device with which a second rotor speed can be reached individually at a spinning position, which can be selected in a simple manner regardless of the production speed according to the spinning conditions.

Another object of the invention is to provide a piecing process that improves the success and quality of the piecing.

This object is achieved according to the invention in that, in addition to the collective drive, a stationary auxiliary drive is provided which can be individually assigned to the spinning element of each spinning station instead of the collective drive. This second stationary auxiliary drive, which can be individually adjusted to the spinning elements, can be adapted centrally to the piecing speed required for the respective fiber material, the rotor diameter, etc. Since this setting is carried out once per machine or section, such an adaptation to another fiber section etc. takes place economically in terms of material and time. The auxiliary drive is advantageously located in the end frame of the machine.

For the purposes of the invention, the term “spinning element” is intended to encompass all elements that are required for the spinning process. This is preferably a spinning rotor, but in addition to a spinning rotor, this term is also intended to refer to a pair of friction rollers and other elements of a spinning station, e.g. the delivery roller, etc. include.

According to a preferred embodiment of the subject matter of the invention, the auxiliary drive is assigned a drive motor which is separate from the collective drive. As a result, the speed ratio between the two drives can be controlled in a particularly simple manner.

In an alternative embodiment of the subject matter of the invention, however, a single drive motor can also be provided, which is assigned directly to the collective drive and to the auxiliary drive via a transmission gear.

For the purposes of the invention, the term “transmission gearbox” is understood to mean both a gearbox for translating and a gearbox for reducing the speed.

Depending on the production speed and material to be spun, the transmission ratio of the transmission gear can advantageously be set between 95: 100 to 75: 100, so that the spinning speed of the spinning element is only 5% to 25% lower than the production speed.

For many applications, it is not necessary that the spinning unit is gently accelerated from the piecing speed to the production speed. According to the invention, a step plate is provided for the transmission gear in this case.

The transmission gear is preferably infinitely adjustable, it being advantageous if the speed of the auxiliary drive can be increased up to the speed of the collective drive.

It has been shown that even if the fiber beard is suddenly released by the fiber delivery device, the fibers do not suddenly enter the spinning element, but that the amount of fiber entering the spinning element increases along a run-up curve, until finally the amount of fiber in the spinning element per unit of time arrives, which is predetermined by the delivery speed of the fiber delivery device. The auxiliary drive is expediently not accelerable in any way, but rather along this run-up curve of the quantity of fibers reaching the spinning element after the fiber delivery device has been released.

For many purposes it is also advantageous if the auxiliary drive is reversible in its direction of rotation. This is especially true for the friction rollers and the delivery roller.

The auxiliary drive can advantageously be controlled by a control device which is arranged on a maintenance device which can be moved along a plurality of spinning positions and by means of which the entire piecing process is also controlled. According to a preferred embodiment of the subject matter of the invention, the control device controlling the auxiliary drive on the maintenance device is also connected in terms of control to an auxiliary drive device for the device pulling the thread during the piecing process. In this way, a thread take-off speed matched to the speed of the spinning element and the piecing process is achieved. The thread take-off speed can also be controlled asynchronously to the speed of the spinning element, for example to temporarily give the thread an increased rotation for the piecing process.

According to a preferred embodiment of the subject matter of the invention, the collective drive has a main drive belt for simultaneously driving a plurality of spinning elements and the auxiliary drive has an auxiliary drive belt for individually driving a spinning element. The main drive belt drives all normal spinning elements at the same speed during production. In contrast, spinning elements in which a thread is to be re-spun are separated from this main drive belt during the spinning phase and are instead individually driven by the auxiliary drive belt, which in turn is driven at a speed which differs from the speed of the main drive belt. Thus, the spinning element to be spun in each case has a different speed in comparison to the spinning elements of the undisturbed spinning stations driven at production speed.

For reasons of saving material and space, the auxiliary drive belt can be made narrower than the main drive belt. Since the auxiliary drive belt drives only a single spinning element, functional safety is always guaranteed.

The selection of the desired drive for a particular spinning element is advantageously carried out with the aid of an individual switching device, which alternately assigns one of the two drives to the spinning element, the switching device being acted upon by an elastic element such that the main drive belt when the switching device is released to the system Drive element connected to the spinning element in a rotationally fixed manner can be brought or is durable.

Appropriately, a two-armed changeover lever is provided for each spinning station, which carries a main pressure roller on one arm and an auxiliary pressure roller on its other arm for alternating contact of the main drive belt or the auxiliary drive belt on the spinning element. This results in a simple design of the subject matter of the invention.

In order to avoid additional operating elements per spinning station, the changeover lever is preferably connected in terms of control to a brake for the spinning element. This tax-related connection can be implemented in various ways. According to a preferred embodiment of the device according to the invention, the brake is arranged on a brake lever carried by the changeover lever.

According to the invention, the brake for the spinning element and the switching device can be controlled in a simple manner in that the brake lever has at least one driver and, by moving from a neutral spinning position into its end position forming the braking position, lifts the main pressure roller from the main drive belt and through its movement into the other , the end position forming the piecing position causes the auxiliary pressure roller to bear against the auxiliary drive belt.

According to an advantageous embodiment of the subject of the invention, the brake lever is pivotally mounted at one end on the axis of the two-armed lever carrying the main drive roller, is connected at its free end to an actuating device, carries a braking surface between its two ends and is thus in its braking position movable, that the brake lever after reaching its braking position continues its movement by contacting its braking surface on the spinning element causes the switching lever to pivot.

It is advantageous if the spinning element is in the immediate vicinity of the main pressure roller and the distance between the free, actuating end of the brake lever and the brake which can be brought into effect on the spinning element is greater than the distance between the brake and the bearing axis.

According to an advantageous constructive embodiment of the device according to the invention, an intermediate lever is assigned to the brake lever, which is pivotably mounted together with the switch lever on a common axis and one end of which engages with the actuating device and overlaps the two-armed lever of the switch device on its side facing away from the spinning element and the other end of which is connected in an articulated manner to the brake lever, which engages under the two-armed switch lever on its side facing the spinning element. In this way, only small switching forces are required despite the short switching travel.

In order to be able to reduce the driving forces for the actuation of the brake and the changeover device by a more favorable choice of lever arms and drive torques and to increase operational safety, the brake lever is preferably mounted independently of the two-arm lever of the changeover device, the brake lever on both sides of the pivot axis of the two-arm changeover lever each has a driver for optional pivoting of the two-armed lever in one or the other pivoting direction. Due to the fact that the brake lever is mounted independently of the shaft, its pivot point can be selected so that the brake is essentially Chen performs linear movement when it is moved into or out of the braking position. This increases the operational reliability of the device.

In an expedient development of such an embodiment of the subject matter of the invention, the shaft of a spinning element designed as a spinning rotor is mounted in a wedge gap formed by support disks, while the brake lever is movable in the direction of the support disks during its braking movement. This results in particularly advantageous space conditions if the shaft of the spinning rotor is supported with respect to the drive belt and the auxiliary drive belt on the side facing the spinning rotor by a single pair of support disks and on the side facing away from the spinning rotor by a combined axial / radial bearing.

In the case of fully automatic open-end spinning machines, a maintenance device which can be moved along a large number of spinning stations and which can optionally be delivered to each spinning station is usually provided. Here, the maintenance device advantageously has a drive device that can be controlled by a control program for actuating the changeover device.

The switchover device for selectively assigning the collective drive or the central auxiliary drive to a spinning element per spinning station is preferably assigned a control lever which can be pivoted relative to a hinged cover which covers the spinning station. This control lever permits simple control of the device according to the invention, in particular if, in a further expedient embodiment of the subject of the invention, the control lever can assume three relative positions with respect to the cover, with its basic position being flush with the cover, pivoted out of the cover in its braking position and in its braking position The piecing position is pressed into the cover.

In order to also enable the control of the device according to the invention in a simple manner manually, a locking device is expediently assigned to the control lever. During the piecing process, the operator needs both hands for lifting the bobbin, searching for and returning the thread, lowering the bobbin and switching on the fiber feed. The locking device is the prerequisite for the operator not also having to hold the control lever in its piecing position during the piecing process.

If, in a further embodiment of the subject matter of the invention, the locking device is acted upon elastically in such a way that it allows the control lever to move into the piecing position, but prevents return to the production position, and a controllable electromagnet is also assigned to the locking device, then the control lever can be released control so that it returns to the production position in a simple manner by means of an electrical switch. Advantageously, this switch is the switching device that controls the fiber feed, for which purpose the electromagnet is then connected in terms of control to this switching device that controls the fiber feed.

In order to prevent the main pressure roller and its mounting from being subject to premature wear due to an imbalance in the spinning element, a damping device is advantageously assigned to the changeover lever. This is expediently designed as friction damping, which is preferably arranged in the bearing of the switch lever.

The device described above in the construction enables the piecing to be carried out in an optimal manner in a simple manner. For a constant yarn character, it is essential that the rotor speed is kept essentially constant during the spinning process. The yarn production already begins during the piecing process, which is why the piecing according to the invention advantageously takes place at a rotor speed close to the production rotor speed, the piecing rotor speed being chosen as high as possible depending on the fiber material to be spun, rotor diameter etc.

It has been shown that, as a rule, optimal results are achieved with a piecing rotor speed during piecing which is 5% to 25% below the production rotor speed.

The device according to the invention enables, without requiring an individual drive for the spinning element for each spinning station, in a simple and safe manner that each spinning element has a defined piecing speed at the desired time for a desired duration. As a result, a predetermined piecing program can be used, the piecing security is significantly increased compared to the known prior art, and the piecers become cleaner and firmer.

• Fig. 1 in schematischer Daufsicht eine Ausführung des Erfindungsgegenstandes mit zwei Antriebsriemen sowie einem Umschalthebel zum wechselweisen In- und Ausser-Wirkung-Bringen der Antriebsriemen;
• Fig. 2 eine Abwandlung des Erfindungsgegenstandes in der Draufsicht;
• Fig. 3 im Schema eine weitere Abwandlung mit einem stufenlos steuerbaren Übersetzungsgetriebe gemäss der Erfindung;
• Fig. 4 in schematischer Vorderansicht eine mit einer Bremse gekoppelte Vorrichtung gemäss der Erfindung zum wahlweisen Antrieb eines Spinnrotors mit der Betriebsdrehzahl oder einer niedrigeren Anspinndrehzahl;
• Fig. 5 eine Abwandlung der in Fig. 4 gezeigten Vorrichtung in der Vorderansicht;
• Fig. 6 eine erfindungsgemäss ausgebildete Spinnstelle sowie eine mit dieser zusammenarbeitende Wartungsvorrichtung im schematischen Querschnitt;
• Fig. 7 eine Dämpfungsvorrichtung für die erfindungsgemässe Vorrichtung im Schnitt;
• Fig. 8 bis 10 in schematischer Vorderansicht die bevorzugte Ausbildung des Erfindungsgegenstandes mit einem Umschalthebel und einem von diesem unabhängig gelagerten Bremshebel in der Anspinn-, Spinn- bzw. Bremsstellung;
• Fig. 11 in schematischer Seitenansicht eine Spinnstelle mit einem Paar Friktionswalzen sowie einer Lieferwalze mit jeweils einem ersten und einem zweiten Antrieb; und
• Fig. 12 in schematischer Seitenansicht eine Spinnstellenabdeckung sowie einen Steuerhebel, die insbesondere für eine manuelle Steuerung der erfindungsgemässen Vorrichtung geeignet sind.

Several exemplary embodiments of the invention are explained below with reference to drawings. Show it:

• Figure 1 is a schematic plan view of an embodiment of the subject matter of the invention with two drive belts and a switch lever for alternately bringing the drive belts into and out of action.
• 2 shows a modification of the subject of the invention in plan view;
• 3 shows a further modification in the diagram with a continuously variable transmission according to the invention;
• 4 shows a schematic front view of a device coupled to a brake according to the invention for optionally driving a spinning rotor with the operating speed or a lower tightening speed;
• Fig. 5 shows a modification of the device shown in Fig. 4 in front view;
• 6 shows a spinning station designed according to the invention and a maintenance device which cooperates with it in a schematic cross section;
• 7 shows a damping device for the device according to the invention in section;
• 8 to 10 in a schematic front view preferred embodiment of the subject of the invention with a switching lever and a brake lever mounted independently of this in the piecing, spinning or braking position;
• 11 shows a schematic side view of a spinning station with a pair of friction rollers and a delivery roller, each with a first and a second drive; and
• 12 shows a schematic side view of a spinning position cover and a control lever, which are particularly suitable for manual control of the device according to the invention.

The invention is first explained using the example of the embodiment shown in FIG. 1. At each spinning station S, a spinning element designed as a spinning rotor 1 is provided. The spinning rotor 1 is supported by means of a shaft 10 and is driven by means of a main drive belt 5. This main drive belt 5 is part of a collective drive 56, by means of which the spinning rotors 1 of a plurality of spinning stations S arranged next to one another are driven simultaneously with the spinning rotor 1 of the spinning station S shown via this main drive belt 5. The main drive belt 5 in turn receives its drive from a main motor 54 in the machine drive frame 500, which is controlled by a control device 6 in the desired manner.

In addition to the aforementioned collective drive 56, a stationary auxiliary drive 57 is also provided which has an auxiliary drive belt 53 which extends alongside the main drive belt 5 for driving the spinning rotors 1 at normal spinning speed along the machine. While the main drive belt 5 is intended to drive a plurality of spinning rotors 1 together, the auxiliary drive belt 53 has the task of driving only a single spinning rotor 1 in the piecing phase. For this reason, the auxiliary drive belt 53 does not need to be designed as strong, so that a smaller width compared to the width of the skin drive belt 5 is sufficient for it. This has a favorable effect on the space required.

Fig. 1 shows as a central drive for the auxiliary drive belt 53, a transmission 3 with a step pulley 34. This has a first, larger diameter section 340 for driving the main drive belt 5 and a second, smaller diameter section 341 for driving the auxiliary drive belt 53. Das The diameter ratio between the length sections 340 and 341 determines the gradation between the production speed and the starting speed of the spinning rotor 1.

The shaft 10 is mounted with its end facing the spinning rotor 1 in the gusset of a pair of support rollers 11. Its end 100 facing away from the spinning rotor 1 is reduced in diameter and is supported by a combined axial / radial bearing 13 (FIG. 6).

At each spinning station S there is a changeover device 2 with a two-armed changeover lever 20 which is pivotably mounted on an axis 201. On an arm 230, this switch lever 20 carries a main pressure roller 211, which can be brought into contact with the main drive belt 5, while the switch lever 20 carries on its other arm 231 an auxiliary pressure roller 212, which can be brought into contact with the auxiliary drive belt 53.

Between the individual spinning positions S there are support disks 50 and 51 (FIG. 8), which lift the main drive belt 5 or the auxiliary drive belt 53 from the shaft 10 of the spinning rotor 1 when released by the main pressure roller 211 or the auxiliary pressure roller 212. In this way, only the belt 5 or 53 abuts the shaft 10 of the spinning rotor 1, which is forced to this system by the corresponding pressure roller 211 or 212.

If a thread is to be individually spun at a spinning station S after a thread break or for any other reason, then the changeover lever 20 is pivoted at the relevant spinning station S in a manner which will be explained in more detail below in such a way that the main pressure roller 211 den Main drive belt 5 releases, so that the support pulleys 50 and 51 lift this main drive belt 5 from the shaft 10 and the auxiliary pressure roller 212 presses the auxiliary drive belt 53 against the shaft 10 of the spinning rotor 1. The spinning rotor 1 of this spinning station S is thus separated from the collective drive formed by the main drive belt 5 and is now driven at the lower piecing speed.

After piecing, the normal spinning speed is selected again by changing over the changeover lever 20, in that the auxiliary pressure roller 212 releases the auxiliary drive belt 53 - which now stands out from the shaft 10 - and the main pressure roller 211 presses the main drive belt 5 against the shaft 10 of the spinning rotor 1.

The changeover lever 20 thus optionally brings the main drive belt 5 or the auxiliary drive belt 53 to act on the spinning rotor 1.

The switching lever 20 can be controlled in various ways, as will be explained later with reference to various exemplary embodiments. In the simplest case, the switching lever 20 is pivoted by hand.

The setting of the piecing speed by changing the transmission ratio takes place by appropriate selection of the stepped disk 34 in the drive frame 500 of the machine. The speed ratio is thus set for all spinning positions S of the machine, so that the desired adjustment can be achieved quickly when changing lots, yarn numbers or rotors etc.

FIG. 2 shows a modification of the central drive for the auxiliary drive belt 53 shown in FIG. 1. This central drive allows the speed of the auxiliary drive belt 53 to be ramped up in a controlled manner. In this exemplary embodiment, both the main drive belt 5 and the auxiliary drive belt 53 are moved from a central location, namely the drive frame 500, which for this purpose has an auxiliary drive motor 530 in addition to the already mentioned main motor 54. The main drive belt 5 is thereby the main motor 54 is driven by a pulley 540. The speed for the motor 54 and thus for the main drive belt 5 is determined by the control device 6 already mentioned in connection with FIG. 1. The auxiliary drive belt 53 is driven by the auxiliary drive motor 530 via a pulley 531. A control device 63 is assigned to the auxiliary drive motor 530, by means of which the speed for the auxiliary drive motor 530 and thus for the auxiliary drive belt 53 is determined.

The auxiliary drive motor 530 drives the auxiliary drive belt 53 at a speed lower than the speed of the main drive belt 5. It has been shown that, depending on the intended rotational speed of the spinning rotor 1 and its diameter, a spinning speed of the spinning rotor 1 of 75% to 95% of the normal production speed of the spinning rotor 1 ensures a particularly safe spinning. For this reason, the speed difference is chosen so that the speed ratio between piecing speed and spinning speed is in the range between 95: 100 and 75: 100.

The speed gradation is preselected by appropriate setting of the control devices 6 and 63. It can be provided that, with the help of the control device 63, the speed of the auxiliary drive motor 530 is increased to such an extent that the main drive belt 5 and the auxiliary drive belt 53 finally have the same speed. For this purpose, a coupling (not shown) can be provided between the control devices 6 and 63, which also takes into account possible dimensional differences of the pulley 540 and 531.

The piecing cannot always be carried out optimally at the same piecing speed. Depending on the fiber material to be spun, the yarn number, the rotor diameter, etc., a different piecing speed must be selected for piecing in order to achieve perfect piecing in terms of strength and appearance. For this reason, the speed of the auxiliary drive motor 530 compared to the main motor 54, depending on the circumstances - which are essentially influenced by the factors mentioned above - is chosen so that the speed of the spinning rotor 1 is 25% to 5% below the normal production speed lies, which is given to the spinning rotors 1 by means of the main drive belt 5.

The higher the piecing rotor speed, i.e. the less it deviates from the production rotor speed, the less the character of the piecing and the subsequent yarn section deviates from the rest of the yarn. For this reason, the aim is to carry out the piecing at the highest possible rotor speed. Depending on the elasticity of the fiber material, however, the same speed cannot be selected for the spinning rotor 1. If the rotor speed is too high, the yarn being formed is turned over and therefore twisted off so that the thread breaks. If the rotor speed is too low, the piecing deviates too much from the rest of the yarn. In particular in the case of living fiber materials such as cotton or wool, the application is therefore carried out at a rotor speed which is only 5% to 25% below the production rotor speed.

By ramping up the rotor speed from the tightening speed to the normal spinning speed for the subsequent transition of the rotor drive from the auxiliary drive belt 53 to the main drive belt 5, the transfer to the main drive can be carried out without jumps and is therefore gentle on the yarn. The result is fewer yarn breaks.

It has been shown that the fibers do not suddenly enter the spinning rotor 1 after being spun on. The fibers retained in the form of a beard in the not shown delivery device have different lengths and are therefore not simultaneously released after the delivery device is switched on again. First of all, there are only a few fibers that are conveyed to the spinning rotor 1 by the opening device, which is also not shown. Over time, it becomes more until finally the normal delivery quantity reaches the spinning rotor 1. The amount of fibers that get into the spinning rotor 1 increases along a run-up curve, the course of which depends on various factors such as fiber length, delivery speed, etc.

The run-up curve of the auxiliary drive motor 530, which is controlled by the control device 63, can be adapted to the run-up curve of the amount of fiber which enters the spinning rotor 1 after piecing, so that the ratio between the two run-up curves is as constant as possible.

In the exemplary embodiment shown in FIG. 3, the belt pulley 531 of the auxiliary drive belt 53 is likewise - as shown in FIG. 1 - driven by the main drive motor 54 with the interposition of a transmission gear 3. For this purpose, a cone wheel 55 of a cone gear transmission is located on the shaft 541 on which the belt pulley 540 for the drive belt 5 is mounted in a non-positive manner. The second cone wheel 550 of this transmission is located on a shaft 532, which also carries the pulley 531 for the auxiliary drive belt 53. The two cone wheels 55 and 550 are wrapped together by a belt 551, which can be shifted parallel to the shafts 541 and 532 by an adjusting device 630.

In a manner similar to that described for the two motors 54 and 530 (FIG. 2), the speed of the auxiliary drive belt 53 can also be accelerated here after the spinning to the speed of the drive belt 5.

The adjusting device 630, possibly also the control device 6, is connected in a suitable manner for control purposes to a maintenance device 64 which can be moved along the spinning machine. This can be done, for example, by trailing cables, which also ensure the power supply of the maintenance device 64. The previously described speed increase of the auxiliary drive belt 53 can thus be controlled from the movable maintenance device 64.

By means of the adjusting device 630, a be correct basic position of the belt 551 can be determined, by which - taking into account a possible diameter difference between the pulleys 540 and 531 - the transmission ratio between the drives for the main drive belt 5 and the auxiliary drive belt 53 is determined.

3 and 11, the maintenance device 64 carries an auxiliary drive roller 640, which is driven from the maintenance device 64 in a known manner, not shown. This auxiliary drive roller 640 can be brought to bear against a spool 70 at the spinning position S to be spun, in order to return the thread for spinning to the spinning rotor 1 and to pull the thread out of the spinning rotor 1 again after it has been attached. So that a constant relationship between rotor speed and thread take-off speed can be maintained here, the drive of the auxiliary drive roller 640 and the actuating device 630 are coupled to one another in terms of control by means of the maintenance device 64.

The piecing speed is also selected in the device according to FIG. 3 by means of a switch lever 20 provided individually at each spinning station S (see FIGS. 1 and 2).

Fig. 4 shows the switching device 2 shown in FIGS. 1 and 3 with the switching lever 20 in the front view. Such a switch lever 20 is provided individually for each spinning station S. The arm 230 with the main pressure roller 211 is assigned a compression spring 22 which, when the switch lever 20 is released by means of the main pressure roller 211, normally holds the main drive belt 5 in contact with the shaft 10 of the spinning rotor 1.

According to the embodiment shown in FIG. 4, a brake 4 for the spinning element is connected to the switch lever 20 in terms of control. For this purpose, a brake lever 44 is pivotally mounted on the axis 213 of the main pressure roller 211, at the free end of which a pull rod 8 engages. The brake lever 44 is arranged at an angle to the arm 230 of the switch lever 20. Here, its free end is in closer proximity to the plane defined by the main drive belt 5 than the arm 230 of the lever 20. This arm 230 has a stop 232 on its side facing the brake lever 44, at which a stop near the free end of the brake lever 44 provided driver 440 can be brought to the plant.

The brake lever 44 has in the vicinity of the axis 213 a brake pad 441, which can be brought to bear against the shaft 10 of the spinning rotor 1, which is likewise arranged in the immediate vicinity of the main pressure roller 211. The location of the brake lever 44 with the brake pad 441 divides the brake lever 44 into a shorter lever arm 442, which faces the main pressure roller 211, and a longer lever arm 443, which faces the free end on which the pull rod 8 engages.

FIG. 4 shows the device in the spinning position, in which the main drive belt 5 rests on the shaft 10 of the spinning rotor 1. If the spinning rotor 1 is to be stopped, the brake lever 44 is brought to bear against the shaft 10 by means of the pull rod 8 with its brake lining 441 in the direction of the support rollers 11. With further movement of the pull rod 8, the brake lever 44 acts as a two-armed lever, which is supported on the shaft 10 of the spinning rotor 1 and with its lever arm 442 lifts the main pressure roller 211 to such an extent that the main drive belt 5 passes through the support disks 50 and 51 (see FIG. 8 ) is removed from the shaft 10. However, the changeover lever 20 is only pivoted so far that the auxiliary pressure roller 212 does not yet bring the auxiliary drive belt 53 into contact with the shaft 10 of the spinning rotor 1.

If the lower rotor speed is now to be selected for the piecing, the pull rod 8 is moved against the changeover lever 20. The driver 440 of the brake lever 44 comes to rest against the stop 232 of the changeover lever 20. This is pivoted so that the main pressure roller 211 releases the main drive belt 5 and presses the auxiliary pressure roller 212 against the auxiliary drive belt 53. The main drive belt 5 is lifted off the shaft 10 by the support disks 50 and 51, while the auxiliary drive belt 53, which is supported by the stepped roller 34 (FIG. 3), the auxiliary drive motor 530 (FIG. 1) or the conical gear transmission 55, 550 (FIG. 2) is driven at a reduced speed compared to the main drive belt 5, comes to rest on the shaft 10.

Moving the pull rod 8 and thus also the brake lever 44 in one direction thus brakes the spinning rotor 1, with both the main drive belt 5 and the auxiliary drive belt 53 being lifted off the shaft 10, while by moving the pull rod 8 and the brake lever 44 in in the opposite direction, the main drive belt 5 lifts off the shaft 10, while the auxiliary drive belt 53 comes to rest against the shaft 10.

As shown in FIG. 4, the arm 230 of the two-armed switching lever 20 is acted upon by the main pressure roller 211 by a compression spring 22 in such a way that the switching lever 20 returns to its spinning position when it is neither subjected to a pull nor a push by the pull rod 8. In this spinning position, the main pressure roller 211 presses the main drive belt 5 against the shaft 10 of the spinning rotor 1, while the auxiliary pressure roller 212 releases the auxiliary drive belt 53, which is lifted off the shaft 10 by the action of the support disks 50 and 51 (see FIG. 8). By means of this compression spring 22 - or possibly another elastic element - the main drive belt 5 is thus brought into contact with the shaft 10 of the spinning rotor 1 when the switching device 2 is released (or possibly another drive element, for example a drive whorl connected to the spinning rotor 1).

In the embodiment shown in FIG. 5, the brake 4 consists of a driven intermediate lever 45 and the actual brake lever 44. The intermediate lever 45 is arranged on the axis 201 of the changeover lever 20 and, with its end facing the auxiliary drive roller 212, stands by the train rod 8 engaged. In addition, this end of the intermediate lever 45 has a driver 450 which engages over the arm 231 of the switch lever 2 on its side facing away from the shaft 10. The end of the intermediate lever 45 facing the main pressure roller 211 is designed as a fork 451 and engages around a pin 444 at the free end of the brake lever 44 mounted on the axis 213 of the main pressure roller 211. The intermediate lever 45 is thus articulated with the end of the axis 213 of the main pressure roller 211 pivotally mounted brake lever 44 in connection. This carries - as shown in Fig. 4 - a driver 440, with which it can be brought to rest on the side of the arm 230 of the switch lever 20, which faces the shaft 10 of the spinning rotor 1, so that the brake lever 44 with its driver 440 engages under the arm 230 of the switch lever 20.

The arm 231 of the switch lever 20 is acted upon by a tension spring 220 such that when the switch lever 20 is released, the main pressure roller 211 moves the main drive belt 5 against the shaft 10 of the spinning rotor 1.

In this embodiment of the device, the movement devices of the pull rod 8 are reversed in relation to those of the device shown in FIG. 4 in order to achieve certain functions. When the pull rod 8 is lifted, the driver 450 of the intermediate lever 45 is lifted off the arm 231 of the changeover lever 2 and the brake lever 44 is pivoted against the shaft 10 of the spinning rotor 1 by the intermediate lever 45. The spinning rotor 1 is thus stopped. When the movement of the pull rod 8 continues, the brake lever 44 is supported on the shaft 10, which now forms a pivot axis for the brake lever 44, and lifts the main pressure roller 211 off the main drive belt 5 without the auxiliary pressure roller 212 coming into contact with the auxiliary drive belt 53 .

When the pull rod 8 is pulled down, the stop 450 of the intermediate lever 45 causes the changeover lever 2 to be entrained and presses the auxiliary drive belt 53 against the shaft 10 via its auxiliary pressure roller 212 Fig. 8) lifted from the shaft 10 of the spinning rotor 1.

In the basic position of the pull rod 8, the two-armed switch lever 20 assumes the spinning position due to the action of the tension spring 220, in which the spinning rotor 1 receives its drive from the main drive belt 5.

The control of the pull rod 8 can take place with the aid of the device shown in FIG. 6. Here, a spring 80 directly or indirectly continuously exerts a pulling force on the pull rod 8, wherein it is held in the position in which the brake pad 440 of the brake lever 44 is lifted off the shaft 10. The pull rod 8 is connected to a two-armed lever 81 which can be pivoted about an axis 810. The two-armed lever 81 is locked by a control lever 82 pivotable about an axis 820. For this purpose, the control lever 82 has a drive fork 821, which engages around a roller 811 of the lever 81. The control lever 82 is arranged in a slot 700 (FIG. 12) of a cover 7 of the spinning station S and can be moved relative thereto. 6, the control lever 82 is in alignment with the cover 7. In this position I, the changeover lever 20 assumes its spinning position, in which the main pressure roller 211 holds the main drive belt 5 in contact with the shaft 10 of the spinning rotor 1.

If the spinning rotor 1 is to be made accessible for maintenance, the rotor housing (not shown) is opened by folding down the cover 7 (FIG. 6). With this cover 7, the control lever 82 is simultaneously actuated, which is pivoted in the direction of the arrow 83 into the position 11 and thereby releases the lever 81. The spring 80 thus moves the pull rod 8 in such a way that the brake lever 44 is brought into its braking position and the switching lever 20 into its neutral intermediate position, in which neither the main drive belt 5 nor the auxiliary drive belt 53 is in contact with the shaft 10.

After maintenance, the cover 7 (FIG. 6) of the rotor housing (not shown) is closed again. The control lever 82 is left in the folded position for piecing or is brought into this folded position. The brake lever 44 thus continues to assume a braking position.

Matched to the return of the thread end into the spinning element, the control lever 82 is then pressed in the direction of arrow 84 against the action of a return spring 822 into position 111 in the cover 7. Here, the main pressure roller 211 is lifted from the main drive belt 5 and the auxiliary pressure roller 212 is pressed against the auxiliary drive belt 53 via the pull rod 81, so that the spinning rotor 1 is now driven by the auxiliary drive belt 53.

The movement of the control lever 82 independently of or together with the cover 7 can be controlled manually or from the maintenance device 64. In the usual way, this maintenance device 64 has a control device 641 (FIG. 6) which controls the entire piecing process. This control device 641 is connected to a drive device 642 for an unlocking device 643 for the control lever 82 or the cover 7. The drive device 642 is designed, for example, as a camshaft with a plurality of cams, of which one cam also causes the cover 7 and / or the control lever 82 to be returned from the position 11 to the position I, in which it closes flush with the cover 7 . This drive device 642 also has a pin 644 which is pressed against the control lever 82 to switch on the reduced piecing speed and which pivots it out of position I against the action of the return spring 822 into position 111. Thus, the drive device 642 provided in the maintenance device 64 serves to control the changeover lever 20 in such a way that the spinning rotor 1 is stopped via the unlocking device 643, the spinning rotor 1 is driven via the pin 644 for spinning at a reduced rotor speed and in a manner not shown with nor painter production speed is driven.

The above-described design of the device for controlling the drive of a spinning element is particularly suitable for control by a maintenance device 64 which can be moved along the spinning machine.

In manual piecing, the operator needs both hands to return the thread into the spinning rotor 1 and to release the supply of fibers into the spinning rotor 1 in a manner that is precisely timed to this. The operator cannot therefore, as is the case with an embodiment according to FIG. 6 by the maintenance device 64, hold the control lever 82 pressed in the direction of the arrow 84 during the duration of the piecing process.

In order nevertheless to be able to control the rotor speed for the piecing process in a simple manner in the case of manually controlled machines, the device shown in FIG. 6 is modified according to FIG. 12. In this case, the control lever 82 is assigned a locking device 85 which retains the control lever 82 in the piecing position 111. So that the locking device 85 does not have to be actuated both during the movement of the control lever 82 from the production position 1 (see FIG. 6) into the piecing position 111 and for the return movement into the production position, the locking device 85 has an elastically actuated catch 850 which, when opening of the control lever 82 dodges and engages behind the control lever 82 when the piecing position 111 is reached.

To release the control lever 82, the catch 850 is assigned a controllable electromagnet 851.

In the embodiment shown, a switching device 852 for the fiber delivery device 72 (see also FIG. 11) is attached to the cover and is actuated by means of a switching button 853. The switching device 852 is connected via a control device 854 to the aforementioned fiber delivery device 72 and the electromagnet 851 in terms of tax.

For the piecing process, the control lever 82 is brought into the piecing position 111, in which it is secured by the latching catch. The spinning rotor 1 is thus driven in the manner described at a low speed. The thread (not shown) is returned to the collecting surface of the spinning rotor 1 in a known manner. Likewise, the fiber feed to the spinning rotor 1 is switched on in a known manner by actuating the switch button 853 at the desired time. When the piecing process is complete and the usual thread monitor (and therefore not shown) detects the presence of the usual spinning tension, the switch button 853 is released.

At the moment the switch button 853 is released, the control device 854 causes the electromagnet 851 to be briefly excited. This releases the control lever 82 so that it returns to its production position I by the action of the return spring 822, in which it is held by another stop, not shown. The spinning rotor 1 is thus driven again at full production speed.

If the piecing process has failed, the control lever 82 is brought into its piecing position 111 again and the piecing process is repeated.

In practice, an imbalance of the spinning rotor 1 cannot be completely avoided, possibly due to deposits of dirt components in the collecting groove of the spinning rotor 1. In order to prevent this imbalance from leading to increased wear of the main pressure roller 211 of the switch lever 20 and its mounting, a damping device 9 is assigned to the switch lever 20 in the embodiments shown. 1, the damping device 9 is designed as friction damping, which in the exemplary embodiment shown has the shape of a rubber bushing 90.

The damping device 9 can be designed differently. Fig. 7 shows a modification in which an elastic bushing 91 is provided between a disc 26 which rests on the part 27 of the machine frame which supports the axis 201 of the switch lever 20 and the switch lever 20. The axis 201 has at its end facing away from the part 27 a thread 200 onto which a nut 92 and a lock nut 920 are screwed. A compression spring 93 is clamped between the switch lever 20 and a washer 930 on the one hand and the two nuts 92 and 920 and a washer 931 on the other hand. Depending on the preload of the compression spring 93 set by the nut 92 and the lock nut 920, the changeover lever 20 is pressed more or less strongly against the elastic bushing 91, so that the damping effect of the damping device 9 can be set by the preload.

FIG. 5 shows a further modification of a damping device 9 for the switch lever 20. In this embodiment, a piston 94 is connected to the switch lever 20 via a piston rod 940, which piston 95 separates two chambers 950 and 951 from one another. The two chambers 950 and 951 are connected to one another by a throttle line 96, in which, according to the embodiment shown, a throttle valve 960 is installed. The cylinder 95 and the throttle line 96 are filled with a medium which is brought by the piston 94 from one chamber 950 into the other chamber 951 (or vice versa). Due to the small cross-section of the throttle line 96 and the presetting of the throttle valve 960, however, the medium cannot pass unhindered from one chamber to the other, whereby the desired damping is achieved.

As the above description shows, the device for driving at different defined speeds can be designed in different ways. The invention is not only limited to the exemplary embodiments shown. Rather, the various features can be interchanged or exchanged for equivalents or used in other combinations. So it is of course possible, instead of the support rollers 11 shown and combined axial / radial bearings 13, two To provide pairs of discs and a conventional thrust bearing or a conventional direct bearing for the spinning rotor 1.

It is also not necessary to provide two tangential belts (main drive belt 5 and auxiliary drive belt 53) as the drive for the spinning rotors 1. Rather, another suitable collective drive and / or auxiliary drive can also be provided here, for example by driving one or more spinning rotors 1 from a main role via a belt assigned to one or more spinning rotors 1, which more or less wraps around the shaft 10 of the spinning rotor 1 . It is also not necessary for the auxiliary drive 57 to be accommodated in the drive frame 500 of the machine. Alternatively, it can be provided in the middle between several sections of the machine or stationary per section.

The switching device 2 does not necessarily have to be designed as a two-armed switching lever 20. Instead of this two-armed switching lever 20, a separate switching lever can also be provided for both the main pressure roller 211 and the auxiliary pressure roller 212, it only being necessary in a suitable manner to ensure that their movements are coordinated with one another in order to achieve the effects described. This can be done electro-pneumatically or electrically or in some other way. The same also applies to the brake lever, which can be moved by a drive device which is independent of the changeover device 2 but is adapted to its actuation.

Such a device, in which the brake lever 40 is mounted independently of the changeover lever 20, but is nevertheless moved in a coordinated manner, will now be explained with reference to FIGS. 8 to 10.

The brake lever 40 is pivotably mounted on one side of the shaft 10 on a bearing pin 41 and extends over the two support disks 11 and the shaft 10 of the spinning rotor 1 to the other side of the shaft 10. Here is the pull rod by means of a bolt 42 8 connected to the free end of the brake lever 40. The bolt 42 projects beyond the arm 231 of the two-armed switch lever 20 on its side facing away from the shaft 10 of the spinning rotor 1, which is designed as a stop surface 233. The bolt 42 of the brake lever 40 in turn is designed as a stop which can be brought to bear against this stop surface 233 of the switch lever 20.

As indicated schematically, in this exemplary embodiment the control lever 82 is designed as a two-armed lever which carries at its end facing the lever 81 a roller 823 which is encompassed by a fork 812 of the lever 81. The position of the pull rod 8 is thus inevitably controlled depending on the position of the control lever 82.

In the spinning position, in which the control lever 82 assumes its position I (see FIG. 6), the brake lever 40 and the changeover lever 20 assume the position shown in FIG. 9. The switch lever 20 is held in contact with the bolt 42 of the brake lever 40 due to the action of the tension spring 220 with a stop surface 233. In this position of the changeover lever 20, the main pressure roller 211 presses the main drive belt 5 against the shaft 10 of the spinning rotor 1, while the auxiliary pressure roller 212 releases the auxiliary drive belt 53, which is lifted off the shaft 10 by the action of the support rollers 50 and 51.

To stop the spinning rotor 1, the control lever 82 is moved independently of a movement of the cover 7 (see FIG. 6) or together with it in the direction of the arrow 83 (FIG. 10). The pull rod 8 is pulled downward and brings the brake lever 40 with its brake lining 441 to bear against the shaft 10 of the spinning rotor 1. The spinning rotor 1 is stopped. In addition, during this movement, the pull rod 8 brings the driver of the brake lever 40, which is designed as a bolt 42, into contact with the stop surface 233 of the switch lever 20 and finally takes the switch lever 20 with it. The main pressure roller 211 thus releases the main pressure belt 5, so that it is lifted from the shaft 10 by the two support disks 50 and 51 and is therefore no longer driven.

From FIGS. 8 to 10 it can be seen that the distance of the brake lining 441 from the bearing pin 41 can be selected to be relatively large by the mounting of the brake lever 40, independently of the changeover lever 20. The brake pad 441 therefore executes an approximately linear braking movement in the region of the shaft 10 of the spinning rotor 1 during the braking process. This ensures that even when the brake pad 441 is worn to a greater extent, its direction of movement to the shaft 10 does not change significantly, so that regardless of the degree of wear of the brake pad 441, there is no danger that the brake lever 40 can get caught on the shaft 10.

If the maintenance work for which the spinning rotor 1 had been stopped has ended, the piecing is carried out. In coordination with the other operations of the piecing process, the control lever 82 is brought into position 111 in the direction of arrow 84 after the cover 7 has been closed (FIG. 8). The pull rod 8 is thus raised, the bolt 42 releasing the arm 341 of the switch lever 20. During this stroke movement of the pull rod 8, the brake lever 40 is also pivoted about its axis 41. The driver 440 bears against the stop 232 of the switch lever 20. This is pivoted in such a way that the main pressure roller 211 is lifted off the main drive belt 5 and the auxiliary pressure roller 212 is pressed against the auxiliary drive belt 53. As a result, the auxiliary drive belt 53 is brought to rest on the shaft 10 of the spinning rotor 1, which is thus driven by this auxiliary drive belt 53; the main drive belt 5 released by the main pressure roller 211 has been lifted off the shaft 10 by the support rollers 50 and 51.

The brake lever thus serves in the embodiment described with reference to FIGS. 8 to 10 for optionally pivoting the changeover lever 20 in one or the other pivoting direction, in order to be able to do so Way to brake the spinning rotor 1 or to drive it differently from the production speed at a specified piecing speed. After spinning, the spinning rotor 1 can also be brought to the production speed more or less quickly in a controlled manner with the aid of the auxiliary drive belt 53 before the drive of the spinning rotor 1 is transferred back to the main drive belt 5.

11 shows a further modification of an open-end spinning station. In this embodiment, a pair of friction rollers 12 is provided as a spinning element instead of a spinning rotor. The friction rollers 12, of which only one roller can be seen in FIG. 11, each carry a whorl 120, against which either the main drive belt 5 or the auxiliary drive belt 53 bears. For this purpose, each of the two belts 5 and 53 is assigned a fork (not shown). Each of these forks is equipped with a separate lifting drive, e.g. an electromagnet 52 or 520, in terms of control, the two electromagnets 52 and 520 being controlled in a coordinated manner by the control device 641 on the maintenance device 64. For example, by dropping the electromagnet 52 over the fork moved by it, which is equipped with rollers to reduce the friction between the fork and the belt, the main drive belt 5 is brought into contact with the vortex 120, while it releases the vortex 120 when excited. Conversely, the electromagnet 520 can bring the auxiliary drive belt 53 into contact with the whorl 120 when excited and lift the auxiliary drive belt 53 again from the whorl if it falls off. If the electromagnet 52 is excited and the electromagnet 520 has dropped off, the whorl 120 is not driven at all.

The main drive belt 53 can in turn, as described in connection with FIGS. 2 and 3, be driven at a speed which is reduced compared to the speed of the main drive belt 5 and then accelerated up to the speed of the main drive belt 5 so that the transfer of the drive to the main drive belt 5 can be done bumpless. The auxiliary drive belt 53 can, however, also be reversed by the maintenance device 64 in its transport direction depending on a piecing program if this is desired, for example, for cleaning the friction rollers 12. The drive of the friction rollers 12 of other spinning positions remains unaffected, so that these rollers are still driven there by the main drive belt 5 at production speed.

FIG. 11 shows that the fiber material 71 is fed to the friction rollers 12 through a fiber delivery device 72 and a dissolving roller 73. The fiber delivery device 72 has a delivery roller 720 which sits at one end of a delivery shaft 721. The delivery shaft 721 is connected via a coupling 75 to a delivery shaft 722 which carries a worm wheel 723. This is in engagement with a worm 740, which in turn is arranged in a rotationally fixed manner on a main drive shaft 74 forming the collective drive 56.

Between the delivery roller 720 and the clutch 75, the delivery shaft 721 carries a gear 724, which is connected via a chain 725 to a gear 760 in driving connection. Gear 760 is located at the end of an intermediate shaft 76, which is connected to another intermediate shaft 76 via a coupling 750. This carries a worm wheel 762 at its free end and is driven by an auxiliary drive shaft 77 (auxiliary drive 57) via a worm 770.

By appropriately controlling the clutches 75 and 750, the delivery roller 720 can be driven either by the main drive shaft 74 or by the auxiliary drive shaft 77 or by neither of these two shafts 74 and 77. If desired, the delivery roller 720 can also be rotated counter to the feed direction by the auxiliary drive shaft 77 in order to bring the fiber beard out of the region of the opening roller 73. This reversal of the direction of rotation can be initiated from the usual thread monitor (not shown) or from the maintenance device 64.

After piecing, the auxiliary drive shaft 77 can be accelerated synchronously with the spool 70 and / or with the friction rollers 12 to the production speed specified by the main drive shaft 74, whereupon the drive will pass from the auxiliary drive shaft 77 to the main drive shaft 74 by simultaneous actuation of the clutches 75 and 750 . It goes without saying that such a control of the delivery roller can also be used in connection with a spinning element designed as a spinning motor 1 (see FIGS. 1 to 10).

Claims (37)

1. An open end spinning machine having a plurality of adjacent spinning stations whose spinning elements are driven by a common overall drive, characterised by a stationary auxiliary drive (57) adapted to be individually associated instead of the overall drive (56) with the spinning element (1, 12, 72) of any spinning station (S).

2. A spinning machine according to claim 1, characterised in that the auxiliary drive (57) is disposed in the power frame or rack (500).

3. A spinning machine according to claim 1 or 2, characterised in that a driving motor (530) separate from the overall drive (56) is associated with the auxiliary drive (57).

4. A spinning machine according to claim 1 or 2, characterised by a driving motor (54) associated directly with the overall drive (56) and by way of a transmission (3) with the auxiliary drive (57).

5. A spinning machine according to claim 4, characterised in that the ratio of the transmission (3) is adjustable preferably between 95 : 100 and 75 : 100.

6. A spinning machine according to claim 5, characterised in that the transmission (3) has a stepped pulley (34).

7. A spinning machine according to claim 4 or 5, characterised in that the transmission (3) is infinitely adjustable.

8. A spinning machine according to claim 3 or 7, characterised in that the speed of the auxiliary drive (57) can be increased to the speed of the overall drive (56).

9. A spinning machine according to claim 8, characterised in that the auxiliary drive (57) is ac- celeratable along the acceleration curve of the quantity of fibres reaching the spinning element (1, 12) after release of the fibre delivery device (72).

10. A spinning machine according to any of claims 3, 7 and 8, characterised in that the direction of rotation of the auxiliary drive (57) is reversible.

11. A spinning machine according to any of claims 8 to 10, characterised in that the auxiliary drive (57) is controllable by a control device (641) disposed on a servicing device (64) movable along a number of spinning stations (S).

12. A spinning machine according to claim 11, characterised in that the control device (641) on the servicing device (64) which device (641) is controlling the auxiliary drive (57) is in a control relationship with an auxiliary drive device (640) for the device (70) which draws off the yarn during the piecing operation.

13. A spinning machine according to any of claims 1 to 12, characterised in that the overall drive (56) has a main driving belt (5) for driving a number of spinning elements (1, 12, 72) simultaneously and the auxiliary drive (57) has an auxiliary driving belt (53) for driving any spinning element (1, 12, 72) individually.

14. A spinning machine according to claim 13, characterised in that the auxiliary driving belt (53) is narrower than the main driving belt (5).

15. A spinning machine according to claim 13 or 14, characterised in that an individual change over device (2) is provided at each spinning station (S) for the selective association of one of the two drives (56, 57) with the spinning unit (1, 12, 72) and is so acted on by a resilient element (22, 220) that upon release of the change over device (2) the main driving belt (5) can be engaged with or retained on a driving element (10, 120) co-rotating with the spinning element (1, 12, 72).

16. A spinning machine according to any of claims 13 to 15, characterised in that each spinning station (S) has a two-armed change-over lever (20) having, for selectively engaging the main driving belt (5) or the auxiliary driving belt (53) with a spinning element (1, 12, 72), a main pressing roller (211) on its one arm (230) and an auxiliary pressing roller (212) on its other arm (231).

17. A spinning machine according to claim 16, characterised in that the change-over lever (20) is in a control association with a brake (4) for the spinning element (1, 12, 72).

18. A spinning machine according to claim 17, characterised in that the brake (4) is disposed on a brake lever (44) carried by the change-over lever (20).

19. A spinning machine according to claim 17 or 18, wherein the brake lever (44) has at least one entraining member (440) and by its movement from a neutral spinning position into one end position operative at the braking position, disengages the main pressing roller (211) from the main driving belt (5) and, by its movement into the other end position operative at the piecing position, engages the auxiliary pressing roller (212) with the auxiliary driving belt (53).

20. A spinning machine according to claim 19, characterised in that the brake lever (44) is pivotally mounted at one end on the pivot (213) of the two-armed change-over lever (20), such pivot carrying the main pressing roller (211), and is connected at its free end to an actuator (8), and carries a braking surface (441) between its two ends and can be so moved into its braking position as, after reaching its braking position and upon continuing its movement, to pivot the change-over lever (20) by its braking surface (441) abutting the spinning element (1,12,72).

21. A spinning machine according to claim 20, characterised in that the spinning element (1, 12, 72) is disposed very close to the main pressing roller (211) and the distance between the free actuating end of the brake lever (44) and the brake (441) adapted to act on the spinning element (1, 12, 72) is greather than the distance between the brake (441) and the pivot (213).

22. A spinning machine according to any of claims 18 to 21, characterised in that an intermediate lever (45) is associated with a brake lever (44) and pivotally mounted together with the change-over lever (20) on a common pivot (201), one end of the intermediate lever (45) engaging with the actuator (8) and engaging over the two-armed change-over lever (20) on that side thereof remote from the spinning unit (1,12,72) while the other end of the intermediate lever (45) is articulated to the brake lever (44) which engages, with the interposition of an entraining member (440), below the two-armed change-over lever (20) on that side thereof near the spinning element (1, 12, 72).

23. A spinning machine according to claim 17, characterised by a brake lever (40) mounted independently of the two-armed change-over lever (20) and having on either side of the pivot (201) thereof an entraining member (42, 440) forthe selectively pivoting the two-armed change-over lever (20) in one or the other direction.

24. A spinning machine according to any of claims 18 to 23, with a spinning element in the form of a spinning rotor, characterised in that the shaft (10) of the spinning rotor (1) is mounted in a wedge- shaped gap bounded by support discs (11) towards which the brake lever (40, 44) is movable in its braking movement.

25. A spinning machine according to claim 24, characterised in that, as referred to the main driving belt (5) and to the auxiliary driving belt (53), the shaft (10) of the spinning rotor (1) is supported at the end near the spinning rotor (1) by a single pair of support discs (11) and at the end remote from the spinning rotor (1) by a combined axial and radial bearing (13).

26. A spinning machine according to any of claims 1 to 25 with a servicing device movable along a plurality of spinning stations, characterised in that the servicing device (64) has a drive device (642) controllable by a control program and operative to actuate the change-over device (2).

27. A spinning machine according to any of claims 1 to 26, characterised in that for selectively associating the overall drive (56) or the central auxiliary drive (57) with any spinning element (1, 12, 72) each spinning station (S) has a control lever (82) pivotable relatively to a pivotable cover (7) covering the spinning station (S).

28. A spinning machine according to claim 27, characterised in that the control lever (82) can take up three positions (I, II, III) relatively to the cover (7), the control lever (82) being flush with the cover (7) when in the production position (I), being pivoted away from the spinning station (S) in its braking position (II) and being pressed into the cover (7) in its piecing position (III).

29. A spinning machine according to claim 28, characterised in that a locking device (85) is associated with a control lever (82).

30. A spinning machine according to claim 29, characterised in that the locking device (85) is so resiliently biased as to permit the movement of the control lever (82) into its piecing position (III) but to prevent its return to the production position (I) and is associated with a controllable electromagnet (851).

31. A spinning machine according to claim 30, characterised in that the electromagnet (851) is in a control association with a switching device (852) controlling fibre feeding.

32. A spinning machine according to any of claims 28 to 31, characterised by means (853) which permit fibre feed when the control lever (82) is in its piecing position (III), and by means (85) which, after the newly spun yarn has again reached the usual spinning tension, effects return of the control lever (82) into its production position (1) and thus raising of the rotor speed to the production speed.

33. A spinning machine according to any of claims 28 to 32, characterised in that the control lever (82) may be moved from its braking position (II) into its piecing position (III) via its production position (I).

34. A spinning machine according to any of claims 1 to 33, characterised in that a damping device (9) is associated with a change-over device (2).

35. A spinning machine according to claim 34, characterised in that the damping device (9) is a friction damper.

36. A spinning machine according to claim 35, characterised in that the friction damper (9) is disposed in the bearing (20) of the change-over device (2).

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