Abstract: A cassette includes a slack limiter which engages tape extending from reels within the cassette and prevents the tape from unwinding from the reels and developing slack or looseness. In one embodiment, the slack limiter is formed from a thin, flexible, resilient strip of material which includes a mounting portion formed by folding the strip to produce a compression member extending at an acute angle to the slack limiter. In a second embodiment, the slack limiter includes two oppositely extending strips and a mounting portion formed by two folds and an interconnecting compression member. In either embodiment, the mounting portion of the slack limiter is retained in the housing by a receptacle which compressively engages and bows the compression member.

Abstract: A web folding device is disclosed for use in combination with a web processing machine which draws the web from the web folding device in a downstream path of travel, the device comprising:a frame;an upper roller mounted to the frame and extending horizontally across the path of travel of the unfolded web;a motor driven roller mounted to the frame below the upper roller and extending horizontally across the path of travel of the folded web;a pair of fold plates mounted to the frame and disposed between the upper roller and motor driven roller, the fold plates defining a channel through which the web passes and is folded by the fold plates contacting the surface of the web on opposite sides of the fold line;a driven exit roller mounted to the frame and positioned downstream from the motor driven roller;at least one drive belt connecting the motor driven roller to the driven exit roller, such that both rollers rotate in the same downstream direction;whereby when the web processing machine is not drawing the web

Abstract: A tape loop sensing arm comprises an arm member (6) which carries a rotary guide (5), comprising a cylindrical guide member (74) mounted on a spindle (65) which pivots on an axle (64) aligned radially with respect to the axis of rotation of the arm member.

Abstract: An automatically controlled twine-wrapping mechanism for a large round baler includes a hydraulically driven twine arm for feeding twine across the width of a bale during the last part of its formation in a bale chamber. The twine passes between a planar surface of the arm and a generally rectangular tensioner plate which is slidably received on a pin carried by the surface and is spring biased towards the surface. The tensioner plate includes contiguous beveled edges which respectively aid in the threading of and in the passage of twine through the tensioner. The tensioner plate also includes a straight edge on the side thereof from which the twine exits. This edge serves to impede reverse movement of twine through the tensioner.

Abstract: The invention includes apparatus for and process of forming a plurality of plastic mounting envelopes from continuous plastic sheet material through cutting the plastic and bead sealing the margins by providing a high energy source to sever the plastic and bond the marginal edge of said plastic without physical contact.The invention also includes said plastic envelopes to serve as mounts and protectors for receiving flat paper objects such as stamps, letters, etc.

Abstract: A tractor feed assembly for an automatic printer. A manually operated tension bar is provided between the tractor feeder and the printer platen. The bar is locked in place by a spring that biases a knob attached to the bar into locking contact with a member formed on or attached to the tractor feed frame.

Abstract: The present invention is directed to a magnetic recording tape cartridge capable of preventing the loosening of a magnetic recording tape comprising a tape adjusting member made of a resilient plate for stretching an intermediate portion of the magnetic recording tape; a pair of wall members formed in the cartridge with a gap defined therebetween to removing or detachably receive the tape adjusting member; and a raised member projected from a main plate portion of the tape adjusting member which is adapted to be engaged with a part of one of the wall members, thereby preventing undesired displacement of the tape adjusting member.

Abstract: A guide device for tape-like recording media, especially a reversing guide device for magnetic tapes, that are transported at high speed, which comprises at least one guide roll, around whose periphery the recording medium is guided, and which is rotatably mounted in bearings, a deliberate specific braking torque being produced between the guide roll and its bearings. Further embodiments concern the roughness of the roll's peripheral surface, the design of flanges for the lateral guidance of the recording medium and the use of two guide rolls. The braking torque is produced by braking means acting on the guide roll. The novel guide device can be used advantageously in any high-speed magnetic tape transport apparatus for the recording/reproduction of any type of audio, video or data signal.

Abstract: A tape cassette is so arranged that an endless tape, stored in a tape accumulating portion in a cassette body, to which a front lid is pivotally movably secured, to thereby assume an open position and a closed position with respect to a front opening in the cassette, and pulled out of the cassette body, is again drawn into the cassette body, by means of a tape drawing reel mounted in a position displaced to one side from the center of the cassette body. A pair of elastic members are disposed in an elastically contracting relation to each other, with the free ends thereof facing a tape discharge gate within the cassette body, so that the endless tape can pass through the pair of elastic members. The tape cassette further includes a rotatably mounted, reverse rotation check member; and a flexible member attached at one end or in the intermediate portion thereof to the cassette body, with the other end maintained in pressure-contact with an elastic member surrounding the flank portion of the tape drawing reel.

Abstract: In a magnetic tape transport, a pivoting tape tension arm has a shaft mounted in bearings in a housing that is pre-formed to be mountable on the transport in only one indexed relationship of transport and housing, and the orientation of the arm with respect to the housing is secured by means within the housing that is fully indexed during the manufacture and assemby of the arm and housing.

Abstract: To permit compensation and guidance for different paths (A, B) of a paper web through a printing machine, for example, selectively, for offset lithographic printing, di-lithographic printing, or flexo printing, a paper deflection roller is positionable between two base or fixed positions (A, B) in dependence on the selected printing mode and hence paper path, and, additionally, in a superimposed movement, deflectable to control the paper tension between adjacent printing stations (1, 2, 3, 4) so that tension between printing stations of the web can be individually controlled and maintained at a suitable level, applicable also to low-strength paper, such as recycled paper.

Abstract: Bidirectional tape drive systems have first and second tape drive capstans and first and second tape drives for rotating, respectively, the first and second tape drive capstans. The first capstan is angularly movable relative to the first capstan drive and a first elastic coupling restrains relative angular movement between the first capstan and the first capstan drive. Similarly, the second capstan is angularly movable relative to the second capstan drive and a second elastic coupling restrains relative angular movement between the second capstan and the second capstan drive. In this manner, tape tension is maintained above zero when the bidirectional tape drive changes directions, and excessive tension upon application of the tape assembly to the tape drive is avoided, while tape slack upon removal of the tape assembly from the tape drive is automatically taken up.

Abstract: An improved cassette having a flexible resilient slack limiter tab installed in a housing of the cassette without the use of adhesive. The slack limiter tab includes a tape contact end portion and a tapered projection. The housing of the cassette comprises rigid walls defining a receptacle which frictionally receives and compressively holds the tapered projection with the contact end portion biased into engagement with tape of the cassette to press the tape against a support surface of the housing to limit slack in the tape.

Abstract: A reel to reel magnetic tape cassette having a tape guide adjacent the supply reel comprising a rotatable element and a guide adjacent the take up reel which is a non-rotatable element whereby frictional resistance of the tape is reduced at the unreeling side and loosening or slack of the tape during transport is minimized.

Abstract: A tape of a tape-recording device passes between a braking roller, a first sound shaft, a second sound shaft, and a pulling roller located one after the other. The pulling forces of the rollers and the slips of the tape of the sound shafts are adjusted so that the pulling force of the tape between the braking roller and the first sound shaft and the pulling force of the tape between the first and second sound shafts are directed toward the braking roller whereas the pulling force of the tape between the second sound shaft and the pulling roller changes the direction to the opposite and is smaller than the pulling force of the tape between the first and second sound shafts.

Abstract: The present invention relates to a material dispensing apparatus having a unique closed loop servo system for advancing material to a receiving machine in accordance with the use demands thereof.

Abstract: A tension regulator for magnetic recording tape, which comprises a plurality of side members forming an encased columnar space having an open top for receiving a flexible tape loop. One of the side members is adjustably positionable relative to the other side member for changing the cross-sectional area of the columnar space in order to vary the tension applied to the flexible tape being received by the tension regulator.

Abstract: A label printer for printing both human readable and machine readable indicia on the end label in a strip of perforated label stock includes a drum printer providing printing at a print station and label advancing rollers for advancing the label stock from a supply through the print station. Human readable indicia are printed on the end label during this advancement. Label tensioning rollers are provided on the opposite side of the print station from the label advancing rollers and engage the end label after a portion of the label has been transported past the print station. When the label tensioning rollers have engaged the end label, the machine readable indicia are printed on the label, as well as any additional human readable indica. The label tensioning rollers provide for tensioning of the label during printing of the machine readable indicia so as to enhance the resolution of the printed indicia.

Abstract: Ribbon feed from a ribbon supply spool is controlled in an incrementing ribbon feed system by a pawl and ratchet brake device actuated by ribbon tension. The mechanism utilizes a single-band spring member to control ribbon tension and ribbon metering.

Abstract: This invention relates to a tape transport for use with a transducer to transport tape along a predetermined path extending past the transducer, comprising two capstans, each disposed at a respective end of the predetermined path; two rollers, each disposed adjacent a respective one of the capstans and arranged to guide tape beyond the respective end of the path in partial wrapping engagement about its respective capstan; two motors each coupled to a respective one of the capstans; and a control circuit coupled to the motors and arranged to control operation thereof to drive the capstans at differing torques whereby to induce a controlled tension in tape extending along the path. One of the motors is driven by an independent source of signals, and the other is driven so as to be dependent, in part, of the operation of the first motor.

Abstract: Apparatus for removing curl from a continuous moving web. The apparatus includes cylindrical members for supporting and directing the continuous web during its travel and a pair of engagement members between which the web travels. The engagement members are pivotally movable so that either surface of the web can be engaged by one of the engagement members with any desired degree of pressure for removing the curl in the continuous web during travel thereof. If the curl is upwardly, the engagement members are pivoted to engage one surface of the continuous web. If the curl is downwardly, the engagement members are pivoted to engage the opposite surface of the web. The degree of pressure applied for decurl action can be adjusted by adjusting the angle of the engagement members with respect to the line of travel of the continuous web. The apparatus also includes brush members engageable with the web to control the tensional forces upon the web as the web engages one or both of the engagement members.

Abstract: A flexible sheet transport system comprising a primary mechanism for feeding the flexible sheet at a predetermined velocity in either a forward or a reverse direction, a tension roller assembly disposed in the path of the flexible sheet so as to be frictionally engaged thereby, an auxiliary drive mechanism for applying tension to the flexible sheet, a coupling assembly connected between the tension roller assembly and the auxiliary drive mechanism and driven thereby in a given sense tending to rotate the tension roller in a direction to move the flexible sheet in the reverse direction. Included in the coupling assembly is a slip coupling that slips in response to application of a given torque and a unidirectional coupling that prevents movement of the coupling assembly in a sense opposite to the given sense.

Abstract: A vacuum actuated guide and tension control system for use in a corrugated paperboard manufacturing plant or the like. The vacuum actuated guide includes a smooth paper contacting surface having a plurality of spaced openings through which a vacuum is imposed upon a sheet passing thereby. The guide, acting upon paper which is being unwound from a roll, or otherwise being operated upon during movement, urges the paper into frictional pressure contact with the perforated smooth surface. The tension placed upon the paper is controlled automatically by varying the amount of negative pressure to which the paper is subjected. In the event of a paper break or other unexpected happening, the operator can actuate a switch and instantaneously terminate the vacuum enabling an instant shutdown of the machine and correction of the problem.

Abstract: Web unwound from a supply roll is slit into a plurality of bands by a slitting unit comprising circular disc blades. The individual bands are subjected to tension by a brake roll assembly positioned before the take up roll to hold the individual bands taut with a predetermined braking force in such manner that different degrees of slippage relative to the brake roll and the individual bands are effected.

Abstract: A web splicing device for a cigarette making machine, includes a reservoir in which web is accumulated prior to splicing, and a suction brake acting on the web after it leaves the reservoir so as to tension the web, characterized in that there is an auxiliary suction brake, upstream of the first-mentioned suction brake, having a guide which during normal operation holds the web away from the auxiliary suction brake in view of the tension in the web, but allows the web to engage the auxiliary suction brake when the tension falls as a result of web being accumulated in the reservoir in preparation for splicing or for any other reason.

Abstract: Method and apparatus for controlling tension in a longitudinally moving web between fixed material feeding points while maintaining the length of the path of web movement between said fixed points substantially constant. Two axially fixed, web-feeding rollers are positively driven from a common drive motor. One roller is driven at a variable speed through a shaft-mounted transmission unit having a variable pitch pulley spaced from the axis of rotation of the roller shaft and connected to the motor by a flexible belt. Fluid piston means provides a constant force on the transmission unit in a direction about the roller shaft axis to impose a constant torque on the variable speed roller and to move the variable pitch pulley to increase or decrease the speed of the roller, thereby maintaining a constant imposed tension on the material in its path of movement between the two rollers.

Abstract: This invention provides an improved method and apparatus for controlling the tension in a tensionally fragile web of material being pulled by a constant speed processing machine from either one of a pair of supply rolls. A first festooning roller effects the control of the web tension during the normal operation of the machine. During the splicing of the web from one supply roll to another, the tension in the web would tend to dramatically increase. This tendency is offset by a second festooning roller engageable with the web and shiftable in a web tension decreasing direction only upon the occurrence of web tensions substantially in excess of the normal tension range. Means are provided to restrict the rate of return movement of the second festooning roller to that which falls within the control limits of the first festooning roller, thus eliminating any tendency to accelerate the new supply roll to a speed above the desired machine operating speed.

Abstract: An apparatus for controlling the tension on yarn withdrawn from a mass of compacted yarn within a confined space has a yarn guide element with a tubular wall portion defining a confined space for guiding and for accumulating a compacted mass of yarn, an inlet opening for entry of the compacted yarn mass into one end of the confined space and an outlet opening for allowing withdrawal of the yarn as a yarn bundle from the confined space. The outlet opening is an elongated slot that is provided in the wall portion of the yarn guide element and that applies tension to the yarn bundle withdrawn from the confined space. The slot has a preselected configuration so that the slot will vary the tension applied to the yarn bundle as the yarn mass moves from one end of the confined space to the other end.

Abstract: An apparatus for transporting webs of photographic material or the like has a web supply roll from which the web is pulled by a pull-off device. According to the invention a tilt arm is mounted intermediate the supply roll and the pull-off device and carries a roller at one end about which the web is drawn off, causing the arm to tilt. Tilting is resisted by a spring acting upon the other end of the arm. An arrangement is provided for varying the resisting force of the spring as a function of the tilted position of the arm.

Abstract: Printing platen for positioning a recording medium such as paper which includes an evacuated chamber having a slotted face plate for attracting, holding and guiding the paper. Slots are arranged parallel to each other and the direction of paper travel, and the vacuum attraction causes temporary deformation of the paper so that the slots can effect guiding and tension on the paper during advancement. Effective platen length can be varied to accommodate different paper widths.

Abstract: An apparatus for ganging and cutting a plurality of layers of strip material in predetermined lengths includes a frame supporting a drive and driven roller acting together to draw the layers of material to a cutter where the layers of material are severed. The drive roller, acting with the driven roller, draws a plurality of layers of material from a rack structure where each layer is individually wound on a rotatable roll. Each layer of strip material is drawn from a roll and a plurality of layers are ganged over a cylindrical roller. The ganged layers of material are directed over a convex-concave roller combination to maintain alignment. The layers of material are then drawn over an upper support roller and are guided to the drive roller through a guide plate structure. The guide plate structure includes a back plate having a slot therein and a top plate having a longitudinal shoulder corresponding to the slot.

Abstract: A tape tension arm arrangement for selectively disposing a pair of tension rollers supported by respective tension arms in positions appropriate for tape loading or tape drive. Each tension arm is mounted on a pivoted rocker member which is coupled to a driving crank member by a connecting rod. The connecting rod engages the rocker member in such a manner that in the tape drive position the tension arm may move against a resilient bias towards the tape threading position, in response to an increase in the tension of the tape. A tape transport system is also described which includes a tape tension arm arrangement of the type described above and a reel mounting device for supporting a reel having an internal support surface. The reel mounting device includes three resiliently coupled reel mounting members each supported between symmetrically disposed pivot points.

Abstract: A cable is supported and advanced by two moving assemblies disposed in the form of a V and each preferably comprising a notched belt of rectangular cross-section. Rollers supporting the notched belts are in turn supported by shafts and are placed overhangingly on these shafts, the lower ends of which are connected to a frame. Neither the frame nor the drive means exceed the driving belts in width. A holding assembly, supported by a framework which has four uprights and also does not exceed the driving belts in width, is removable, and the uprights are hinged to the upper ends of fixed shafts of the intermediate rollers.

Abstract: A stuffed ribbon cartridge for a serial impact printer includes flexible leaders for guiding the ribbon from a stationary storage position to a movable print point. In order to place tension on the ribbon which is stored in the cartridge in a stuffed condition, a clip which pinches the ribbon so as to produce a drag force on the ribbon is located adjacent the print point and spaced from the cartridge by a substantial length of the flexible leader.

Abstract: This invention relates to devices for maintaining uniform the slack of a continuum of material while it is in process. One embodiment, particularly useful with machinery for wrapping tire-bead chafing strips, comprises an axle-mounted idler roll wherein the axle is supported by a pair of ball bushings mounted one each on support rods. The axes of the rods are parallel and variably inclineable so as to increase selectively the slope of the axes along which the ball bushings are impelled gravitationally, in opposition to the continuum of material as it is looped about and moves past or over the surface of the roll.

Abstract: A tensioning device for materials of tape form particularly adapted for metic printers and comprises a floating element situated between free sections of a paper tape installed in return fashion in a driving mechanism. The floating element is provided with displacement transmission elements formed by spiked belts of which the spikes are engaged in perforations in the tape. The tensioning of the tape is provided by a weight hooked to the floating element such that the tape section emerging from the driving mechanism is driven, via the floating element, by the tape section which enters the driving mechanism.

Abstract: A device that permits the rapid removal of fiber glass roving from a coil thereof, for movement of the roving to a chopping and spraying gun, wherein the device provides considerable drag to the roving when it is no longer pulled firmly. The device includes a tube that is pivotally mounted on a support, so that the tube can pivot to best align itself with roving moving, therethrough, and then can pivot away from that orientation to cause the roving to undergo sharper bends in passing into and out of the tube, so as to apply braking forces to the roving. The support for the tube can include a pair of rods that fit closely within the corners of a standard roving box, and can also include clamps on the rods that clamp to the box, for facilitating mounting of the tube.

Abstract: A low cost pneumatic stock feeder for punch presses and the like wherein a one-piece U-shaped main frame is provided for supporting and guiding a reciprocating feed slide. One end of a stock gripper bar is pivotally secured to the feed slide while the other end thereof is adapted to be actuated by a fluid motor carried by said feed slide whereby an efficient mechanical advantage is afforded for the stock gripping action. A continuously acting friction braking means is provided for engaging just the longitudinal side corners of the stock material so that the latter may be yieldably held during the time when the gripper bar is released and so that there is a minimum of marring or scratching of that portion of the stock material from which parts are to be stamped.

Abstract: A tape guide has a tape supporting surface extending across a major surface of an advancing tape at a supporting region extending from a tape touchdown region to a tape liftoff region. The tape guide stresses the advancing tape with the tape supporting surface uniformly across the tape and at both tape edges. A reference surface extends at an acute angle to the supporting surface between and exclusive of the tape touchdown and liftoff regions in order to position the advancing tape at one of its tape edges.

Abstract: A sewing machine thread snubber having a fixed part and having a movable part pivoted thereon is provided with mechanism operable by needle bar reciprocating mechanism for moving the pivoted part of the snubber between a needle thread releasing position and a position wherein a drag is imposed on the thread.

Abstract: A web supply and take-up system in which the web is transported from a supply reel to a take-up reel by means of a capstan and pressure roller. The take-up reel is driven to wind up the transported web. The improvement comprises a roller mounted for restricted rotation and placed between the supply and take-up reels in frictional engagement with the web. The roller supplies a counter force to the take-up reel drive force which assists the capstan and pressure roller in stopping undesired web movement.

Abstract: Apparatus for automatically dampening a strip moving longitudinally in its own plane as a result of a variable pulling force applied to the strip comprising: a strip deflector for engaging a surface of the moving strip and deflecting the strip; a guide for guiding the deflector in a path extending at an angle to the plane of the moving strip; a dampening device for biasing the deflector in a first direction to engage and push against the moving strip and form permitting movement of the deflector in an opposite direction when the strip pushes against the deflector as a result of rapid and violent increase in the pulling force on the strip, the dampening device including a pneumatic cylinder having a piston forming first and second chambers within the cylinder, a piston rod connected to the piston and extending through one end of the cylinder, the piston rod being connected to the deflector so as to bias the latter in said first direction and so that movement of the deflector in said opposite direction by the m

Abstract: The device for feeding yarn in a textile machine comprises a set of feed driving rollers rotating at a speed exceeding the maximum yarn processing speed in the machine, a first yarn brake downstream of the driving rollers, a first swing support upstream of the rollers, a second yarn brake and a second swing support. Each swing support includes a movable member exerting by its weight a tension against the yarn which causes the latter to engage frictionally the driving rollers. The frictional force exceeds the force of the first yarn brake and advances the yarn about a length which is sufficient to cause the moving member of the first swing support to abut against a fixed stop member so that the tension is released from the yarn and the holding friction changes to a sliding friction which is lower than the braking force of the first brake and thus stops the decoiling of the yarn.

Abstract: The disclosure relates to a multi-roll tension bridle for hot and cold rolled steel strip, in which at least the first roll of the bridle is provided with an internally mounted normally non-rotating electromagnet for causing the strip to be attracted against the entry portion of the roll in order to create a pretensioning in the portion of the strip immediately adjacent the entry side of the bridle, thereby causing the bridle drive motor to load up preventing slippage of strip on the roll.

Abstract: Lead-in apparatus for positioning sheet stock for feed along a generally straight path to an intermittent operation press or the like, including a lead-in roll assembly and a stock brake assembly to respectively maintain the stock relatively steady and provide it with a frictional drag as it advances towards the press. The lead-in roll assembly includes a first roll over which the stock is adapted to pass and a second roller under which the stock passes. The second roller is journaled between the spaced arms of a bracket pivotally mounted on the axis of the first roller whereby the height of the second roller may be readily adjusted relative to the first roller and the strip stock passing therebetween. The brake assembly includes upper and lower friction brakes which impart the desired frictional drag to the sheet stock when positioned in their closed attitude.

Abstract: Winding device for metal strips, in which the metal strip is braked between two rollers which are pressed against one another. One of the rollers has a larger angle of wrap for the metal strip of at least 75.degree. and the other roller has a smaller angle of wrap for the metal strip of 45.degree. at maximum. The one roller with the larger wrap includes material on its periphery having a coefficient of friction for the material which is at least 20% lower relative to the braked metal strip than the coefficient of friction of the peripheral material of the other roller with the smaller amount of wrap.

Abstract: A material guiding device for feeding material to a stitch-forming area of a sewing machine which has a rail guide over which the material is placed for guiding movement from a charging point to the stitch-forming area, comprises a braking weight which has a bottom recess of a size to receive the rail guide with the material thereon so as to permit engagement of the weight over the material so as to move with the material during the feeding operation and to provide a braking action thereon. The construction includes a deflector adjacent the stitch-forming area which deflects the weight into a braking weight return track in the form of a slide or chute which has an opening adjacent the stitch-forming area and is inclined downwardly to a delivery end which is remote from the stitch area at the charging point for the material so that a weight may be returned automatically to a place at which it may be applied to a material at the charging point.

Abstract: A high speed color reproduction machine comprised of four separate xerographic type processing units, one for each of the primary colors plus black. The multiple processing units are arranged in close nested relationship to one another with the image transfer stations thereof in close succession along the path of movement of the copy substrate material. A combination air flotation type and vacuum based belt transport system is employed to bring copy substrate material from a supply source into transfer relation with the successive processing units. Exposure of the processing unit's photoreceptors is simultaneous. A precise dimensional relationship between photoreceptor length and spacing for each processing unit assures registration of the color images produced with one another. Following transfer of the last color image, the image bearing copy material is brought to a fuser where the image is fixed. The finished copy is thereafter discharged, or returned for a second duplex pass.

Abstract: Disclosure is made of an apparatus for winding strips, preferably in longitudinal cutting of a tape of separating material for storage battery electrodes, wherein at least two drawing rollers are connected to a drive for their rotation so as to provide for the tape movement through a cutting mechanism; at least two receiving shafts are coupled to said drive by means of a friction clutch, the shaft axes running in parallel with the axes of said drawing rollers; said receiving shafts are provided with a set of spools for winding adjacent strips on said spools of different receiving shafts; said receiving shafts are also provided with longitudinal slots extending along the entire length thereof, and spool is provided with a stop received in the longitudinal slots of the receiving shafts to provide for tensioning of the tape upon slacking.

Abstract: A device is disclosed for tensioning a running length of textile yarn. The device contains a yarn passageway made up of three sections, each section having a progressively larger diameter from the inlet end of the device. A small diameter section at the entrance end of the device has a seat adjacent the inner end thereof which receives a spherical element. The medium diameter section surrounds the seat and retains the spherical element therein. The larger diameter section of the passageway is sufficiently large to enable pressurized air to pass around the spherical element without forcing the element out the end of the passageway. The wall adjacent the junction of the large and medium diameter sections is tapered so as to permit ready return of the spherical element to the medium diameter section to reside on the seat. Mounting means are also provided for securing the device to a yarn handling machine.