Abstract: Disclosed is a weaving machine, including: a yarn tensioning system for keeping a pile-warp yarn under tension, including a local control unit, a drive motor Wand a drive roller; and a detection device for detecting abnormal variations in the pile-forming, including: a measuring system, for measuring, with the aid of the drive motor and the drive roller, pile-warp yarn consumption xm of the pile-warp yarn per cycle unit of one or more weft insertion cycles; a reference system, for determining for each cycle unit whether the pile-warp yarn is interlaced in a figure-forming manner and for determining the expected pile-warp yarn consumption xt; and a computing system, for comparing the measured with the expected pile-warp yarn consumption when the pile-warp yarn is interlaced in a figure-forming manner, and for detecting, on the basis of this comparison, abnormal variations. In addition, disclosed is an associated method for detecting abnormal variations in pile-forming in a weaving machine.

Abstract: A circular knitting machine structure comprises knitting needles and sinkers. Each knitting needle is controlled to move on a first half knitting track or a second half knitting track. A retracting time point of the first half knitting track is later than that of the second half knitting track. One side of the sinker facing the knitting needle is formed with an inclined plane. When the knitting needle is used for knitting, a surface yarn and a bottom yarn are fed therein. When the knitting needle moves on the first half knitting track, a standard plating is knitted without changing the position of the surface yarn. When the knitting needle moves on the second half knitting track, the surface yarn leans against the inclined plane of the sinker transitorily, the position of the surface yarn is changed relatively to the bottom yarn, and an interchanged plating is knitted.

Abstract: A pickup device for picking up a knitted tubular manufacture from a circular knitting machine for hosiery or the like and for transferring it to a unit adapted to perform additional operations on the manufacture, comprising an annular pickup body that supports a plurality of pickup elements, which are arranged radially around the axis of the pickup body and can slide with respect to the pickup body along radial directions; the pickup body can be arranged coaxially around the needle cylinder of a circular knitting machine for hosiery or the like, with each one of the pickup elements laterally facing a needle of the machine; actuation means are provided which act on the pickup elements for their movement along the radial directions at least from a first position, in which the pickup elements are closer to the axis of the pickup body, to a second position.

Abstract: A system and method for managing the feed of a plurality of yarns at constant tension and/or velocity to a textile machine of circular, loom or yarn preparation type, the yarns being fed to the machine by a corresponding plurality of feed devices. Setting controller is provided, connected to the plurality of devices and arranged to set their operation, the setting controller receiving synchronization signals from the machine and measuring on the basis of these signals every portion of an article production cycle, the cycle being divided into different stages, the setting controller acting on each individual feed device on the basis of the stages such that each feed device feeds the respective yarn with predefined tension and/or velocity individual to each of the stages.

Abstract: A method and device for automatically measuring the yarn length absorbed by a rectilinear machine adapted to produce an article and comprising a carriage (3) movable to-and-fro over a needle bed (1) between two ends of a working path, needles (2) moving towards said carriage (3) to cooperate with the yarn (F) and form an article, said yarn unwinding from a feeder (5) comprising means for measuring the yarn quantity fed at constant tension towards said needle bed; the feeder (5) measures and constantly monitors the yarn feed velocity, this monitoring enabling the fed and knitted yarn quantity to be obtained in real time and each measurement to be associated with the respective carriage travel stroke, this information enabling precise regulation of the knitting cams.

Abstract: A yarn feeding device for a knitting machine comprises a motor for driving a roller from which a yarn is fed out, and a rotatable arm which intermediately stores the yarn fed out from the roller, and the yarn is fed from the arm to a knitting machine body. A torque generator is provided to apply a variable torque to the arm. A yarn speed is obtained from a loop length of a stitch for each knitting needle and a knitting speed calculated on the basis of knitting data used in the knitting machine body. The yarn speed is converted into a torque to be applied to a buffer using a conversion table at each knitting section in a knitting course so as to correct a yarn tension fluctuation caused by the yarn speed, and the torque generator is controlled in accordance with the torque thus obtained. The yarn tension fluctuation is reduced so that high-speed knitting and knitting using a weak yarn can be facilitated.

Abstract: A motorized yarn-winding drum holds a plurality of loops of yarn wound thereon and is driven to rotate for drawing said yarn from a reel and feeding it to a general downstream machine. A movable guiding member is biased to slideably engage the yarn unwinding from the drum and to deviate its path, by a spring acting in contrast to the tension of the yarn, thereby generating a reserve releasable in response to tension peaks on the yarn. The stroke of the guiding member is limited by a stop defining a position of maximum deviation of the yarn. The spring has one end operatively connected to the guiding member and one opposite end connected to driving elements operable for applying a load to the spring, with the guiding member abutting against said stop. The driving elements are controlled by a control unit which is programmed to adjust the load as a function of a desired feeding tension.

Abstract: A method for feeding a plurality of yarns with constant values of fed length to a textile machine (5), each yarn (2) unwinding from a spool (1) and cooperating with a usual feed device (4), arranged to maintain the tension of the yarn (2) at a predefined constant value before being directed to the textile machine (5), there being provided at least one control unit (6) for controlling the feed to said machine (5); an absorbed yarn length value to be maintained for each yarn (2) fed to the textile machine (5) is set or self-learnt, an actual value of the yarn length effectively absorbed by said machine (5) is measured, and this predefined value is compared with the actual value, to act upon one or more feed devices (4) and modify the tension value of the corresponding yarn (2) whenever this comparison indicates a deformity between said predefined values and the actual measured values, said tension modification making these absorbed yarn length values equal to the predefined value.

Abstract: When elastomeric yarns are unwound and fed to the needles of a circular knitting apparatus, a yarn package relaxation profile is set, or determined, with corresponding adjustments made to the unwinding speed based on such package relaxation profile. Variably compensating for a varying package relaxation while knitting results in more uniform properties in a circular knit fabric and improved elastomeric yarn yield.

Abstract: An object of the invention is to be provide a yarn feeding apparatus of a flat knitting machine capable of accurately predicting a required amount of a knitting yarn and knitting a fabric while supplying knitting yarn necessary for knitting. The knitting yarn is fed out based on an idea shown in a solid line in consideration of a yarn speed corresponding to the requirement for knitting yarn produced according to the movement of a yarn feeding member as shown by chain lines in FIG. 6(b). A knitting yarn is stored on a buffer rod at a start of knitting because the speed of a motor such as a servo motor for feeding a knitting yarn lags behind the yarn speed. A knitting yarn that runs short at the time of deceleration at an end of knitting is also fed out in advance.

Abstract: A method for circularly knitting an elastomeric yarn into a knitted fabric is provided. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.

Abstract: A method for circularly knitting an elastomeric yarn into a knitted fabric is provided. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.

Abstract: A method for circularly knitting an elastomeric yarn into a knitted fabric is provided. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.

Abstract: A precision yarn (14) delivery system for the delivery of yarn from a yarn supply to a yarn utilising point, comprising a temporary yarn store (22) intermediate the supply and the utilisation point in which the yarn (14) is held under low tension and is fed from the store as required by the utilisation point.

Abstract: A fluctuation in tension of a knitting yarn to be fed is reduced, and the knitting yarn having an accurate length is fed even if the amount of demand for the knitting yarn is suddenly changed. A knitting yarn is interposed between a main roller and a driven roller and is thus fed, and is supplied from a yarn feeding port to a fabric, with storage depending on an inclination of a buffer rod. A yarn feeding controller predicts the amount of demand for the knitting yarn based on a signal sent from a knitting controller and PID controls a servo motor such that a position of a tip portion of the buffer rod aims for a position of an origin according to the inclination angle of the buffer rod, which angle is detected by an inclination angle sensor.

Abstract: A mechanism to automatically control tension of supplemental yarns added to a weaving or knitting machine has a pivotal control arm, one end of which is influenced by the tension of the yarn being controlled, while a counteracting force is applied to another end of the arm. The movement of the arm is used to modulate and adjust a braking device acting against the yarn holding spool to keep the tension of the yarn substantially uniform over time as the diameter of the yarn wound on the storage spool changes.

Abstract: A device (1) for controlling the feed of yarn (11) fed to a textile machine (10) such as a knitting machine, hosiery machine or a bobbin winder, comprises means (18) for ascertaining the yarn tension and means (3, 12) for measuring its feed velocity to the textile machine (10), said ascertainment and measurement being effected by evaluation and control means (20) which enable said tension and velocity values to be established with precision. A method implemented using the aforesaid device enables the evaluation and control means to control and regulate the operation of the textile machine (10) and for example the stitch length in a knitting or hosiery machine.

Abstract: An improvement in a yarn-holding apparatus for a circular knitting machine which functions to hold a plurality of yarn ends in the ready position at the air shoe near the machine yarn feeds so that the held yarn ends can be selectively engaged by the yarn feeds and thereafter introduced to the needles of the machine for knitting. An air input station receives air from an airflow source and has a manifold into which the introduced air is directed. A number of air ports are connected with and extend from the manifold thus sending a number of airflow streams into the airflow passage where the yarns are introduced. The directed airflow streams converge to maintain the held yarns in a stationary and tangle-free condition and enable the positive engagement of the yarns by the yarn feeds.

Abstract: A uniform yarn delivery method and apparatus for a knitting machine is disclosed. The method comprises the steps of sending yarn derived from a supply cone to be guided on a yarn supply drum so as to tighten yarn thereon; and suitably uniformly slackening the taut yarn sent from yarn supply drum prior to sending to said knitting machine for knitting under the same vibration of a yarn tension detection arm. With this, all yarn sections are the same in length, loops are identical, and fabric has a uniform texture.

Abstract: For producing a knitted product on a flat knitting machine with simultaneous supply of two threads of different elasticities to needles of the machine, for each stitch to be formed the length of the thread of the higher elasticity to be supplied to a needle is calculated from the supplied length of a thread of the lower elasticity and the data about the material property of the thread of the higher elasticity, and a feeding device is controlled for the thread of the higher elasticity in correspondence with the calculated thread length to be supplied.

Abstract: A device for feeding an elastically extendable yarn to hosiery knitting machines, which includes a positive yarn feeder composed of two mutually opposite contrarotating rollers which have parallel axes and between which the yarn to be fed passes. Elements are provided for rotationally actuating at least one of the rollers about its own axis with a rotation rate which can vary on command. Downstream of the positive feeder along the yarn feed direction, there are arranged elements for detecting the tension of the yarn and a programmable control and monitoring unit which is operatively connected to the detector elements. The control and monitoring unit compares the yarn tension detected by the detector elements with a yarn tension which is preset in the control and monitoring unit.

Abstract: For supplying yarns, a yarn supply apparatus is contemplated that is designed particularly for knitting machines whose yarn demand fluctuates greatly over time. The yarn supply apparatus has a rotor-driven yarn wheel, which in the ideal case furnishes yarn directly to the knitting machine or its yarn guides without the interposition of yarn storage devices. The yarn tension is monitored by means of a yarn tension sensor, which provides measured value detection for a closed-loop controller that controls the supply by the yarn wheel. The controller is also embodied such that it can process signals that contain information about the future yarn demand. Thus in the event of imminent drastic changes in demand, of the kind that in flatbed knitting machines periodically occur at the edges of the knitted goods (turning points of the yarn guide), the controller can react by presupplying yarn or by ceasing to supply yarn. Yarn tension spikes and overly steep yarn tension drops can thus be compensated for.

Abstract: A sweater knit fabric containing hard yarn plaited together with bare elastomeric yarn is provided. The elastomeric yarn has substantially uniform draft along each course in the fabric. The fabric is made by a process in which the bare elastomeric yarn is fed under substantially uniform tension to a knitting machine in which yarn demand fluctuates as the fabric is knitted. Sweater knit fabrics are useful in making garments such as sweaters, vests, dresses, pants, skirts, shirts and caps.

Abstract: A rotation speed control apparatus for a yam winding storage drum has a unit for driving the drum, and a scanning device for scanning the quantity of storage windings on the drum which provides signals proportional with the number of the storage windings. The scanning device includes a light source for generating light beams along optical paths guided so as to impact the surface of the storage windings wound on the drum. A plurality of sensors are arranged so as to receive a related light beam along a respective light path with a light intensity varying in proportion with the number of storage windings. A plurality of light guiding blocks are each arranged on a respective one of the optical paths between the storage windings and the sensors.

Abstract: A plate-type thread brake includes two brake elements pressed resiliently against each other by a load device and receiving the thread passing through between them. These brake elements are eccentrically suspended on bearings on the inside wall of a central opening which only fill out a small part of the opening. Thread guides are also arranged in the region of this central opening.

Abstract: A thread control device for a flat knitting machine having a housing and at least one thread brake arranged on the housing, has a spring acting on the thread brake, a flat spring web supported at one side, and a slider movable in a recess of the housing and having a foot which slides on the spring web so that a free end of the flat spring changes a force of the spring which acts on the thread brake in correspondence with a position of the slider.

Abstract: The yarn feeding device for a yarn-consuming textile machine includes a mechanism for positively feeding yarn to a textile machine according to predetermined yarn consuming speed changes and timings of those changes, this mechanism having a rotary yarn feeding element (1,83) carrying a main yarn reserve (84), a motor (82) for rotating the yarn feeding element (1,83) at a motor rotation speed according to the variable yarn consuming speed and a motor controller (51, 57) for controlling the motor; a yarn reserve device (3,78; 20, 77) for building up or reducing an auxiliary yarn reserve consisting of a portion of yarn extending between the main yarn reserve and the textile machine, when changes in the yarn consuming speed occur that are so rapid that the motor (82) temporarily cannot change the motor rotation speed to deliver yarn from the rotary yarn feeding element at the yarn consuming speed because of motor inertia; a controller for the yarn reserve device (3,78; 20,77) which increases or decreases the auxi

Abstract: The thread feeding device has a supporting element for a spool of thread to be fed, and a variable-speed motor having a body connected to the supporting element and an output shaft connected to an arm that is rotatable about the axis of the spool with respect to the spool itself. The arm is provided, proximate to its end that is spaced from the spool axis, with a thread passage so as to perform, as a consequence of its own rotation, the gradual unwinding of the thread from the spool. The device also has an actuation and control element that drives the motor with a speed that can vary according to the tension required for the thread during feeding.

Abstract: A disk brake for placing tension on textile yarns is provided with an air-cleaning system for blowing lint and fiber dust particularly from the underside of the disks to prevent a buildup which may interfere with operation of the brake disks and prevent proper clamping action between the disks.

Abstract: A yarn brake has two brake disks, retained with axial play in a support or bearing device, which are retained against one another via resiliently yielding device, such as permanent magnets. The brake disks are rotatably supported in the support or bearing device. Via an oscillatory motion generator, such as an electromagnet, mechanical or other device, the support or bearing means is set into mechanical oscillation that is essentially axial to the brake disks or in other words parallel to the axis of rotation defined by the rotation of the brake disks. The brake disks are carried along only slightly or not at all by the support or bearing device and the oscillatory motion generator.

Abstract: A break in twice as many yarns is made detectable merely by slightly modifying the tension switch assembly of a knitting machine. A yarn conductor 20 is rotatably attached to the forward end of an arm 16 of the assembly and provided with a pair of yarn supports 26, 27 on opposite sides of a rotational pin 19. Upon a break occurring in the yarn 2 retained on one of the yarns supports 26, 27, torques exerted by the yarns 2, 2 on the respective supports 26, 27 are brought out of balance to rotate the yarn conductor 20 and release the remaining other yarn 2 from the support 27.

Abstract: A method and apparatus for maintaining a moving string of waxed thread at a tension. A tensioner mounting frame has a thread input opening for receiving waxed thread from a thread supply, and a thread output opening for outputting the string of waxed thread at a preset tension. A tensioner arm with a plurality of eyelets affixed thereto is provided for guiding the string of waxed thread. The tensioner arm is pivotally connected to the tensioner mounting frame. A plurality of tensioner rods are also provided for guiding the string of waxed thread, the plurality of tensioner rods are rigidly affixed to the tensioner mounting frame. A spring, having a first end coupled to the tensioner mounting frame and a second end coupled to the tensioner arm, creates a tension in the string of waxed thread. A heating device is affixed to the tensioner mounting frame and is provided for warming the apparatus during its operation.

Abstract: A weft yarn presentation apparatus has a weft sequence control having weft thread presenting devices (1), a controlled thread clamping device (2) with several clamps (3a-3f) and a guide member (4) with a slit (5). The association of the weft thread presenting devices (1) with the clamps (3a-3f) guarantees that there is no cross-over of the tracks of the weft threads, and the displacement of the clamps in the reference plane (6) does not influence these tracks. The weft thread is presented to the gripper in the reference plane (6), through matching of the movements of the clamp and of the associated weft thread presenting device (1) so that contact between the weft threads is prevented.

Abstract: A yarn tensioner or brake for textile knitting machines having several tensioners on a support rod, each tensioner having a pair of tension cups which are pressed against each other by compressed springs supported from a stationary support. In a first embodiment, a stationary tension cup forms the stationary support and a floating tension cup alternates with respect to a stationary tension cup of an adjacent tensioner. The stationary tension cups have cylindrical protruding guides which slip fit into and guide the floating tension cups. In another embodiment, a stationary support supports compressed springs on both sides. The stationary support is formed of a circular support wall which has cylindrical protrusions on opposing sides and sized to slip fit into respective floating tension cups. A pair of stationary supports positioned on the support rod to support and guide opposing floating tension cups against each other. Each respective floating tension cup is driven by a respective coil spring.

Abstract: A thread brake with two disc shaped or plate shaped brake elements resiliently pressed against each other operates with an associated oscillation generating device to set the brake elements in oscillatory motions which are preferably oriented transversely to the bearing axis of the brake elements.

Abstract: A feeder apparatus for automatically controlling in real time the tension of a textile yarn, includes a control device for continuously controlling the tension of the textile yarn, before supplying it to a textile machine, the control device controlling a swinging lever arranged downstream of a drum and driving an adjustable movable shield element adapted to intercept a light, thermal or electromagnetic radiation impinging on a sensor which transforms the received radiation into an electronic signal proportional to said radiation and driving a display of the yarn tension.

Abstract: A disk brake for textile yarns is mounted upon a horizontal brake support for a warp creel with the disk axis disposed perpendicularly to the brake support. The upper disk can be adjustably loaded for adjusting the braking force. The entire adjustable range of the brake can be controlled with a single spring, which is below the horizontal brake support. The brake spring is disposed parallel to the brake support and is attached at one end preferably to an adjuster that can be shifted relative to the brake support and at the other end to a pivoting lever arm which presses vertically downwardly on the upper disk under the influence of the brake spring.

Abstract: An apparatus which provides for servo regulation of a yarn furnisher for a circular knitting machine which permits the knitting machine to operate at a higher speed, controls and varies the tension of the yarn supplied to a knitting machine, and provides a two-bagging unit receptacle for the directing and receiving of the knitted products.

Abstract: The circular knitting machine, for manufacturing open fabric, has a thread clamping and cutting device arranged inside the needle cylinder and there is a thread engagement element which is controllably movable from the inside of the needle cylinder toward the outside, and vice versa, in the needle cylinder region which faces the dial, so as to engage the threads at the end of their knitting and so as to carry the threads to undergo the action of a presser element, and a cutting element.

Abstract: An automatic stitch cam adjustment mechanism for a circular knitting machine is disclosed. The knitting machine includes a plurality of knitting needles supported in a rotating needle cylinder for vertical movement parallel to the axis of rotation of the needle cylinder. A plurality of cam support brackets surround the needle cylinder, and a plurality of stitch cam support members are slidably mounted on the cam support brackets for vertical movement thereon. Stitch cams are mounted on the stitch cam support members for engaging the needles and lowering the needles to a loop formation point. A drive motor is connected to each of the stitch cam support members for moving the stitch cam support members up and down. Sensors are included for (1) measuring the position of the movable support members along the vertical path of movement, (2) detecting the rotational speed of the needle cylinder, and (3) measuring a feeding characteristic of the yarn such as yarn feed tension or quantity.

Abstract: The arrangement provides warp threads for an oscillating weft thread magazine for warp knitting machine. The machine uses a creel, a first delivery device with constant delivery speed, and a second delivery device with a variable thread drive speed. The latter speed corresponds to the instantaneous take-off speed of the weft thread by the carriage. A storage arrangement is located between the two delivery devices for smoothing out the differences between the constant delivery speed and the variable take-off speed. This arrangement enables use of elastic weft threads on the weft thread magazine, so that they are provided in a state of constant tension stage; in particular, tension-free or very slightly tensioned.

Abstract: A thread supply device for multi-system circular knitting machines has at least one warp beam accommodated rotatablhy in a receiving frame. On the warp beam are wound the threads associated with the individual knitting systems in the form of adjacent thread winding areas with equal axial lengths and equal diameters. The warp beam is connected with a drive and driven thereby in such a way that it always delivers to the knitting systems the average thread quantitites consumed thereby during operation of the circular knitting machine irrespective of the momentary diameters of the thread winding areas.

Abstract: Yarn 10 is fed from a package 11 to a point of knitting 12 on a knitting machine along a substantially closed path defined by tubing 13. Adjacent to a positive feeding device 14, the tubing 13 includes a section 15 which can be closed for initial blowing of the yarn through the tube, and opened to allow threading of the yarn 10 around the feeding device 14. This facilitates initial feeding of the yarn to the knitting machine, and also helps in the control of loose fly or lint generated from the yarn 10. The section 15 includes a tensioning device (30, not shown) for the yarn.

Abstract: Thread-tensioning and guide device provided for fastening to the needle-bed ends of a flat knitting machine has, on a stationary machine part (20), a pivotably mounted supporting arm (10) for each thread to be fed, the device parts influenced by the thread to be fed being distributed to the supporting arm (10) and to the stationary machine part (20), and, in the operating position of the supporting arm (10), parts of the stationary machine part (20) interacting with elements arranged on the supporting arm or being accessible through the supporting arm for setting purposes. This design of the device allows a favorable combination of a thread-tension brake influenced by a thread-tension regulator with a specially designed pick-up tensioner.

Abstract: A yarn supply apparatus for textile machines, particularly for knitting machines, has a rotatable yarn supply means supplying yarn under essentially slipless conditions to the textile machine; a speed controlled motor coupled to the yarn supply means controls the rotation of the yarn supply means. A movable yarn tension element is positioned in the path of yarn from the yarn supply means to the textile machine and is subjected to a bias force means that determines the yarn tension. A yarn reserve zone is formed in the path of the yarn from the yarn tension element to at least one of the yarn guide elements, the size of this zone depending on the position of the yarn tension element. Coupled with the yarn tension element is a transducer that provides a signal representative of the position or movement of the yarn tension element to an electrical circuit that includes the drive motor.

Abstract: In a method and apparatus for adjusting the length and the mesh structure of a knitted article produced on a flat knitting machine, a yarn tension sensor is provided in the path of the yarn to be knitted for controlling the yarn tension, which sensor controls a yarn brake and/or a yarn restoring spring in the path before the yarn tension sensor via a process controller.

Abstract: The yarn guide element for textile machines comprises a longitudinally extending guide member oriented along a yarn path and having a smooth upper surface free of edges, in particular a tensioned wire (15). In flat knitting machines, the guide members comprising a tensioned wire (15) can be arranged singly or as a plurality spaced from one another and parallel to and beneath the yarn feeder rails (20/1-20/3) and can extend over the whole active length of the needle beds. (FIG. 6).

Abstract: A yarn brake of a plurality pairs of discs spaced apart along a straight rod of uniform non-circular section mounted in path of yarn as it is fed to the knitting needles.

Abstract: The take up means (5) is inhibited in response to a predetermined operating conditions of the flat knitting machine.

Abstract: A yarn supply element (5, 150) that supplies the yarn substantially without slip and is rotatably supported has yarn guide elements (14, 15, 16; 158) and is coupled to an electric motor (3) of regulated frequency that drives it. In the yarn travel path following the yarn supply element, there are yarn tension sensing means (21) that monitor the yarn (17) unwinding from the yarn supply element and that emit and electrical signal that is supplied to a control circuit (52), which supplies the motor with a frequency signal. To assure satisfactory yarn supply even in the event of abrupt changes in yarn utilization, a device (21, 19) for forming a yarn reserve is provided along the yarn travel path following the yarn supply element. The size of the yarn reserve is dimensioned to be sufficient to cover the yarn requirement during start up of the motor. Associated with this device are means (28, 50-55) for automatically refilling the yarn reserve to an original size no later than after the startup of the motor.