US2610813A - Apparatus for regulating yarn tension - Google Patents

Description

Sept. 1952- P. J. CAMPBELL 2,610,813

APPARATUS FOR REGULATING YARN TENSION Filed March 12, 1946 4 Sheets-Sheet 1 [NVENTOIZ 1900/ J. Campbe ZMW Sept. 16', 1952 P. J. CAMPBELL" APPARATUS FOR REGULATING YARN TENSION 4 Sheets-Sheet 2 Filed March 12, 1946 INVENTOQ Sept. 16, 1952 P. J. CAMPBELL APPARATUS FOR REGULATING YARN TENSION 4 Sheets-Sheet 3 Filed March 12, 1946 I/NVENTOIZ C J. 5 m 6 V AC E Z r 1 a V x mm m 4 u M o m m R 3 Z 2 H I N n H1 iv 1 4. 4. .Wnm Fu Jr H v 0 7x 1 0% 7 m n 2 r 4 sq 5% 9 B.

a o bcl/ By Sept. 16, 1952 Filed March 12, 1946 P. J. CAMPBELL APPARATUS FOR REGULATING YARN TENSION 4 Sheets-Sheet 4 PRESSURE GAUGE n RELIEF //26 I VALVE I24 /22. 1/8 20 n/ FAowRassuRELJneuEFLl AIR UAIR l.

- REGULATOR m VALVE n com nzssognnuznr INVENTOR Pau/ J. Camp be Patented Sept. 16, 1952 APPARATU S FOR REGULATING YARN TENSION Paul J. Campbell, Berlin,v Conn assignor, by mesneassignments, to Raymond Engineering Laboratory, Inc.,- Middletown, Conn., a corporation of Connecticut Application March 12, 1946, Serial No. 653,850

The invention relates particularly to an appa-- ratus for regulating the tension in one'or more moving strands of material such as yarn, as for instance in one or more such strands being wound onto a rotating'beam or equivalent device and being-unwound from oneor more packages;-

The word yarn will herein be used in a generic sense to include not only material oi thetypes commonly designated as yarn, but also other. materials as to which there may be necessityfor.

winding under controlled tension. I

Oneof' the general objects of the invention is to provide a regulator unit for use with a single strand of yarn and'having improved means for maintaining the tension in the yarn strand substantially constant as it leaves the unit. Constant tension is maintained notwithstanding variations in the tension in the yarn as it moves to the unit and notwithstanding variations in the operating conditions, such as variations in the size and texture of the yarn and variations in humidity. Othervariations in the tension in the yarn passing to the regulator'unit may be due'to the unwinding operation, suchfor instance as the tendency of'the unwinding thread to stick between the adjacent wound coils of the package.

A more specific object of the invention is to provide a regulator unit wherein the required.

regulation of the tension-to maintain it constant is effected by fluid actuated means and more parcularly by pneumatic means.

A further more specific object of the invention is to provide a regulator unit having a means, such as a friction means, for resistingthe movement of the yarn so as to provide tension therein,

and having fluid actuated means, such as pneumatic means, for varying the resistance applied to the yarn by the resisting means, the action of the said fluid actuated means being controlled by the tension of the yarn after passing the said resisting means.

A still further more specific object of the invention is to provide a regulator unit having a means, such as a friction means, which resists the movement of the yarn so as to provide tension therein, and which is bodily movable as the result of variations in the said tension, and having fluid actuated means, such as pneumatic means, for

varying the resistance applied to the yarn by the resisting means, the said resistance being varied in accordance with the said bodily movement of the resisting means. v

A still further specific object of the invention is to provide a regulator unit wherein the tension in the moving yarn is maintained normally con 41 Claims. (01. 242-150) stant, but wherein the amount of the said nor.-' mally constant tension may be controlled and adjusted by fluid actuated means, such as pneumatic means.

I Another general object of the invention is to provide an apparatus comprising a plurality of similar regulator units each having means adapted to control the amount of tension in its own strand of yarn andto maintain-such tension constant, and also comprising a common fluid pressure actuated means for providing uniform and constant tension in the strands of yarn at all of the units and for uniformly varying the amount of the said uniform and constant tension.

Other objects of the invention will be apparent from the following specification and claims.

In the drawings I have shown in detail a preferred embodiment of the invention and such embodimentwill be full described, but it will be understood that various changes may be made from the construction shown and described and that the drawings and description are not to be construed as defining or limiting the scope of the invention, the claims forminga-part of this specification being relied upon for that purpose.

Of the drawings,

- Fig. 1 is a plan view of one of theunits' of the apparatus with a portion broken away. i

Fig. 2 is a front view of the unit shown in Fig. 1.

Fig. 3 is a side view of the unit shown in Fig. l with a portion broken away.

,Fig. 4 is a fragmentary side view similar to Fig. 3 but showing the friction members in engagement with a strand of yarn and also showing the primary tension means which is omitted in Figs. 1 and 3.

Fig. 5 is an enlarged front view of the unit with the front cover removed and with the upper portion shown in vertical section along the line 5-5 of Fig. 3.

Fig. 6 is a fragmentary view similar to Fig. 5 but showing the friction membersin engagement with a strand of yarn. v

Fig. .7 is an enlarged vertical sectional view taken along the line 1-1 of Fig. 5.

Fig. 8 is a diagrammatic view of an apparatus embodying the invention and including a plurality of the units shown in detail in Figs. 1 to 7.

The general objects of the invention and some of the more specific objects thereof have been particularly stated. The details of. construction will be -described in detail by reference to the drawings, particularly Figs. 1 to 7 thereof.

A main casing or housing I is provided which carries the various parts of the unit and encloses some of them. The casing has a front cover [2 and a top cover [4 which carries some of the parts of the unit. A means is provided for resisting the movement of the yarn, and this means preferably has direct frictional engagement with the yarn and includes two separate relativel movable friction members. As shown, the friction members are oppositely cupped washers l6 and I8 which are rotatable about a common verticalaxis, but which may tilt to slightly shift the positions of their axes as will be more fully explained. A supporting element 20 is provided for the friction washers l6 and I8, this element beingsupported within the housing Ill. The element 20 extends through an opening 2| in the top cover l4, and the washers are located above the said cover. Carried by the supporting element 20 is a means for moving the lower friction washer I8 upward toward the upper friction washer IS. The said means for moving the friction washer I8 is preferably fluid actuated, and as shown, it comprises a piston 22 rigidly secured to the supporting element 20, the upper portion of which is cylindrical. The said means also comprises a cylinder 24 which surrounds the piston 22, being movable vertically with respect thereto. As shown, the cylinder is within the opening 2|.

The cylinder 24 has an upward extending sleeve 26 which surrounds the cylindrical portion of the supporting element, a bearing bushing 28 being interposed between the said sleeve and the cylindrical portion of the supporting element. The lower friction washer l8 rests directly on the top surface of the cylinder 24 and is rotatable thereon, the central aperture in the Washer being substantially larger than the sleeve 26 so as to permit the friction washer to tilt slightly. The upper friction washer I6 has an upward projecting portion which loosely fits and is guided by the upper portion 30 of the supporting element 20, which portion is of reduced diameter. Clearance is provided between the washer l6 and the sleeve 26 so as to permit the washer to tilt slightly. The said portion 30 of the member 20 carries a collar 32, and a friction disc 34 is preferably interposed between the collar 32 and the upward projecting portion of the friction washer [6.

As shown in Fig. 4 and also in Fig. 6, the moving strand of yarn 36 in which the tension is to be regulated passes between the friction washers I6 and I8 causing the said washers to rotate. The said strand of yarn also engages the sleeve 26 formed as a part of the cylinder 24 and such engagement causes the sleeve 26 to rotate, the cylinder 24 being necessarily also rotated. In order that the cylinder 24 may rotate freely clearance is provided between the inner surface of the said cylinder and the outer surface of the piston 22. This clearance is very small and is exaggerated in Figs. and 7 of the drawings.

As shown more clearly in Fig. 7, a tube 31 extends through an aperture in the piston 22 and this tube is connected with a flexible tube 38 by means of which fluid under pressure can be supplied to the space within the cylinder 24 above the piston 22. It will be seen that fluid pressure in the said space will cause the cylinder 24 to move upward and move the friction washer l8 toward the friction washer [6, thus applying friction to the strand of yarn 36 moving between the washers as shown in Fig. 6. When the fluid pressure is changed as hereinafter explained, the amount of friction or resistance is correspondingly changed and the said cylinder and piston therefore constitute means associated with the friction or resistance means for varying the friction or resistance thereof.

.There are certain important advantages in using air asthe fluid for operating the cylinder 24 but the invention is not necessarily so limited. However, in view of the advantages of air, and in order to simplify the description, air will be hereinafter referred to as the fluid being used. It will be apparent that there will be some escape of fluid from the interior of the cylinder 24 through the clearance provided between the interior surface of the cylinder and the exterior surface of the piston. When air is used, the escape of fluid is immaterial, provided that suitable provision therefor is made as will presently be described.

The resistance or friction applied to the strand of yarn depends upon the air pressure in the cylinder and means is provided for varying the said air pressure in accordance with the tension in the strand of yarn after it has passed the said means for applying resistance such as friction. Various means may be provided for enabling variations in yarn tension to cause variations in air pressure, but preferably, the varying of the air pressure in accordance with Y variations in tension is effected by permitting the resisting means, that is, the friction washers l6 and I 8, to move bodily in accordance with the amount of tension. To this end the supporting element 20 is preferably pivotally supported within the casing l0, and as shown, the casing carries a horizontal pin 40 which extends through a bearing sleeve 42 to which the supporting element 20 is rigidly connected. The sleeve 42 is engaged by a washer 46 held in place by a cotter pin 48. The opening 2| in the top plate is of such size as to permit limited pivotal movement of the element 20 and of the parts carried thereby. The air tube 38, being freely flexible, does not interfere with such pivotal movement. Pivotal movement of the supporting element 20 in one direction is limited by means of an adjustable stop 50 extending through an aperture in a boss 52 on the casing ID. The stop is held in adjusted position by means of a set screw 54.

The unit includes a suitable device or means for providing a constant force for resisting the pivotal movement of the supporting element 20 in the direction of yarn tension, that is, in the counterclockwise direction. As concerns certain broader aspects of the invention, this device or means may be widely varied, but preferably and in accordance with other phases of the invention, the said means is fluid actuated and may advantageously be pneumatic. While the invention is not necessarily limited to a pneumatic means, such a means is shown and will be described. There is provided an air chamber 56 formed within a depending boss 58 on the top cover H of the casing. This chamber is closed at its inner side by means of a flexible dia phragm 60 having a contact plate 62 thereon. The diaphragm is held in place by a frame 64. An air passage 66 is provided in the boss 58, this communicating with a rigid tube 68 which in turn is connected with a flexible tube or conduit 10. Air under pressure is supplied through the tubes 10 and 68 to the chamber 56, this pressure tending to move the diaphragm 60 in the inward direction, that is, toward the right, and resisting movement of the said diaphragm in :the opposite or outward direction. Carried bythe supporting element 20 aboveitspivotal axis is a contact member 12 which engages the contact plate 62. 'Ihemember .12 is shown as being a screw extending through a threaded aperture in the supporting element. '1

Fig. 6 is similar to a'portion of Fig. 5, but it shows th parts in operative positions, with the lower friction Washer l8 moved upward by air pressure and engaging thestrandof yarn 36. It will be seen by reference to Fig. 1. that tension in the strand of yarn tends to move the friction means I8, l8 and the associated partsincluding the supporting element 20 in the counterclockwise direction, but that such movement is resisted by the air. pressure in the chamber 56 acting on the diaphragm 60. The air pressure in the-chamber 58 is normally constant and therefore the extent of movement of the frictionmeans'and of the supportin element is a direct function of the tension in the strand of yarn. Normally, equilibrium is established between th yarn tension tending to move the parts in one direction and the air pressure tending to move the parts in the opposite direction. Any change in yarn tension re-f sulting from any cause, such as variations in primary tension ahead of the friction means, or variationsin the size of the yarn or variations in humidity, has a tendency to upset the equilibrium. At the initiation of any such tendency, the action of the friction means is immediately adjusted to change the tension and restore the equilibrium. Any minor increase in yarn tension causes the parts to move in the counterclockwise direction, and any minor decrease in yarn tension allows the parts to be moved in th clockwise direction by the air pressure acting on the diaphragm 60. The said movements resulting from increased or decreased yarn tension are utilized to vary the friction applied to the yarn by the friction means so as to restore the yarn tension to normal, this being done by varying the air pressure within the cylinder 24.

shaped conduit member 14 which is connected with another flexible tube 16 leading from a source of air under pressure. The T-shaped member is positioned in an aperture in a boss 18 on the casing I8, being held in place by a set screw 80. The T-shaped member 14 has a bleed orifice 82, and a portion of the air flowing through moves in the counterclockwise direction under the influence of increased yarn tension air flows more freely through the bleed orifice thus reducing the air pressure transmitted throughthe tube 38 to the cylinder 24. This reduces the pressure applied to the friction washer l8 and correspondingly reduces the tension in the strand of yarn 36, restoring such tension to normal. When the supporting element moves in th clockwise direction as the result of decreased yarn tension, air flows less freely through the bleed orifice, thus increasing the air pressure transmitted through the tube 38 to the cylinder 24. This increases the pressure applied to the friction Washer l8 and correspondingly increases the tension in the strand of yarn 36, restoring such tension to normal. The

The flexible tube 38 is connected with aT-' net result is that the tension in the strand of yarn. 36 is maintained substantially constant, notwithstanding all factors tending to chang it.. .c r

The amount 'of the, constant tension in the strand of yarn may be varied by varying the'force acting in opposition to the tension in th'eyarn, that is, by varying the air pressure in the chamber156. An increase in air pressure tends to move the supporting element 28 in the clockwise. direction, thus increasing the air pressure in the cylinder 24 and increasing the tension in the strandof yarn. Similarly, a decrease in air pressure tends to permit the supporting element 20 to move in the counterclockwise direction, thus decreasing the air pressure in the cylinder-'24 anddecreasing the tension in the strand of yarn. Thus theten sion in the strand of yarn is a direct function of the air pressure in the chamber 56.- The supporting element 20 remains substantially vertical at all times, its position being changed only minutely to provide variations in the amount of restriction of the air flowing from the bleed orifice 82. 'It is additionally subject to minor movements resulting from minor variations in yarn tension, which minor variations are immediately corrected in the manneralready described;

As already stated, the strand of yarn in passing between the Washers I6 and 18 causes them'to rotate, but such rotation is retarded by th friction applied to the washer l6 by the friction disc 38. Both of the Washers l6 and 18 are loosely mounted, and they can readily tilt when necessary to permit a knot in the yarn to pass between them without materially affecting the amount of tension applied to the yarn. The lower washer I8 has a depending skirt which'te'nds to prevent dust and lint from entering the casing through theopening 2L, The entry of dust and lint is further prevented by reason of the fact thatair is escaping past the piston 22 and fromthe bleed. orifice 82 into the interior of the casing 18. This causes a flow of air outward through the opening 2| and this outward fiow prevents the inward movement of dust and lint.

The strand of yarn 36 may have some primary tension therein before reaching the friction washers l6 and I8 and the means for guidin the strand of yarn to the friction means is so located as toavoid any tendency for the said primary tension in the yarn to cause bodily movement of the friction means, that is, pivotal movement about the axis of the pivot pin 40. Preferably,

and as shown, the strandof yarn is guided to the friction washers in a direction approximately perpendicular to the direction of bodily or' pivotal movement. Some primary tension is usually desirably so long as it is less than the minimum tension required in the strand after it passes the friction washers- One reason for providing primary tension is that it overcomes the tendency, which otherwisefrequently exists, for the strand of yarn to be guided outward by the washers l6 and I8 so that it is near the peripherie of the washers and out of engagement with the sleeve 26. I'preferably provide a primary tension means of suitable construction, such a means being shown in Fig. 4 and also in Fig. 8.. The housing [0 carries a bracket 84 provided with a vertical. pivot pin 86 on which are mounted two rotatable washers 88 and 98 between which the strand of yarn passes. The weight of the upper Washer 88 serves to tension the yarn. The strand of yarn,

is guided to the washers 88 and 98 by means of an eye 92 on thebracket 84. The eye 92prevents the transmission to the primary tension members.

of any whipping or whirling action resulting from unwinding,

There is a tendency for the mechanism as thus far described to a somewhat unstable. In other words, there is a tendency toward self excited oscillation or vibration of the pivoted element 20 with the parts carried thereby, such a tendency being inherent in any freely movable member subject to normally equal opposed forces, one of which may be subject to minor variations which are automatically corrected. In order to prevent such oscillation or vibration means is provided for insuring a lag in the change ofair pressure in the cylinder 24 as the result of a change in yarn tension. A relatively large air reservoir 94 is provided, preferably in the bottom of the casing I0, this reservoir being closed at the rear by a plate 95, and the flexible tube 16 is connected with a rigid tube 96 extending into the reservoir. Air is supplied to the reservoir 94 through a control member 98 with which is connected an air supply conduit I00. The control member 98 has a diaphragm I02 therein having an orifice I04 of small diameter. Filters I01 are preferably also provided. The orifice I 04 is just large enough to pass enough air to make up for leakage past the piston 22 and for air flow through the bleed orifice 82 when the unit is operating at maximum yarn tension. The pressure in the air supply conduit I is maintained at such an amount, above a critical amount, that the rate of air flow into the reservoir is constant.

With this arrangement, and on account of the flow of air into the relatively large reservoir 94 at a constant rate, the pressure within the cylinder 24 is increased or decreased relatively slowly as the flow of air at the bleed orifice is decreased or increased as the result of changes in yarn tension. Thus, when the equilibrium is destroyed through changes in yarn tension, the said equilibrium is restored relatively slowly without exciting oscillation or vibration of the supporting element 20 and the parts carried thereby. With this arrangement pressure within the cylinder 24 is increased relatively slowly as the rate of flow through the bleed orifice is decreased. Thus, when the equilibrium is destroyed through an increase in yarn tension, the said equilibrium is restored relatively slowly without exciting an oscillation or vibration of the supporting element 20 and the parts carried thereby. While there is a lag in the response of air pressure changes in the cylinder 24 to changes in yarn tension, such lag is very small and may be only a fraction of a second, but it is suflicient to prevent undesirable oscillation or vibration.

The supporting element 20 carries near its lower end a relatively large weight I08 which is adjustable in position and is held in place by means of a set screw I I 0. The weight I08 serves to counterbalance the friction washers and other parts carried by the element 20, so that the center of gravity of all of the pivotally movable parts is at or near the pivotal axis. With the center of gravity at the said axis, there is no tendency for the parts to oscillate as the result of vibration in the supporting framework on which the unit may be mounted. Under some conditions it may be desirable to so adjust the weight that the center of gravity is somewhat below the pivotal axis, the weight thus tending to hold the parts in their central upright positions. Under other conditions, the weight may be adjusted to bring the center of gravity slightly above the pivotal axis, thus providing extreme sensitivity of control when a very small yarn tension is required.

- Ordinarily, yarn tensloning units such as described are used for controlling the tension of a large number of strands of yarn which are being wound onto a rotatable beam or other equivalent device. As many as 1,000 such units may be included in a single installation. Fig. 8 is a diagrammatic view showing three units suitably mounted, these being supported on a suitable creel which is not shown. It will be understood that this view is merely illustrative and that a much larger number of units is ordinarily provided. The strands of yarn 36, 36 are unwound from suitably supported supply packages, such as cones I I2, I I2, and each strand is guided through the corresponding eye 92, between the primary friction washers 88 and 90, thence between the friction washers I6 and I8, and finally to the beam on which they are to be wound.

A main operating air conduit H4 is provided with which the several branch operating conduits I00, I00 are connected. A second main controlling air conduit I I6 is provided with which the several branch controlling conduits I0, I0 are connected. An air compressor I I8 is provided, air flowing to the compressor through a filter I20 and flowing from the compressor through a relief valve I22. The main air conduits H4 and H6 are connected beyond the relief valve I22.

A manually adjustable pressure regulator I24 is connected in the main controlling air conduit I I6, this serving to maintain the pressure constant notwithstanding any variations in the pressure of the air delivered thereto. The pressure regulator can be adjusted to provide different constant pressures. The said main controlling air conduit II6 preferably has a relief valve I28 connected therein. Also connected with the main air conduit H6 is a pressure gage I 28.

It has already been stated that an equilibrium is maintained in each unit between the tension in the corresponding strand of yarn and the pressure in the air chamber 56. The yarn tension can be increased or decreased at all of the units by varying the air pressure in the several chambers 56, this being done by adjusting the pressure regulator I 24. Inasmuch as the said chambers 56 of all of the units are connected with the same main controlling air conduit IIG, it will be seen that the pressure in all of the chambers 56 can be changed simultaneously and uniformly, thus changing the tension in all of the strands of yarn simultaneously and uniformly. The pressure gage I28 can be calibrated to read directly in units of yarn tension such as grams. Thus, by observing the gage I28 and by adjusting the regulator I24 the operator can provide, within the limits of the apparatus, any desired yarn tension in all of the strands. This ready adjustment of the yarn tension at all of the units simultaneously and uniformly is in contrast with the existing conventional practice of individually adjusting or changing all of the very large number of tension regulator units that must be included in one installation.

An apparatus embodying the invention is adapted for use with a wide variety of yarns,

and with suitable adaptations as to details of construction it may be used for materials not ordinarily designated as yarn, such as wires. narrow fabrics and the like. Irrespective of the kind of yarn or other material, the tension is very accurately controlled, this being effected even though there are wide variations in operating conditions. Notwithstanding changes in the manner of unwinding from the package, or changes in the primary tension, or variations in the size of the yarn" or variations in the condition of the yarn due to humidity changes or otherwise, the tension remains substantially'eonstant. The apparatusis p l jfi l a y's for use with elastic yarn wherein the "tension must be keptat practically zero, value to'avoid undue stretching and elongation; f

A very important advantage of the" apparatus is the provision for maintaining the same tension in a large number of strands of yarnand the provision for changing the tension in all of the strands of yarn simultaneously and uniformly. Inasmuchas the various'units ofthe apparatus are exact duplicates of eachjother, the tension applied by'them totheir respective strands oi yarn is adirectiunction oj'rthe pressure of the controlling fluid; this pressure being exactly the same in all of the'unitsfand being subject to changes uniformly affecting all of the units.

What I claim is: a

1. The combination in a tension regulatorflf'or a moving strand of yarn, of means for resisting the movement of the'yarn tojcauseitension thereto the fluid actuated means, means dependent on the tension in the yarn after passing the said friction members for varying the pressure of the fluidsuppliedlto the fluid actuated means to so actuated means carried by the supporting ele in, fluid actuated means acting 0 1' the resisting means to cause the latter to apply resistance to the yarn, means for supplyingffluid under pressureto'thesaid fluid actuated means, and means dependent on the tension'in the yarnjafter' passing the said resisting means for varying the pressure Of the'fluid supplied by the fluidsupplying means to the fluid actuated means'to maintain the said yarn tension substantially constant.

2. The combinationin a tension regulator for a moving strand of"y'arn of relatively-movable friction washers between which "the yam passes, the said Washers being rotatable about substantially common axes underthe influence ofthe moving yarn, fluid actuated nie'ansiactingon one of the washers to press it toward the otherwasher and thereby frictionally resist-- the movement of the yarn and cause'tensiontherein, and means dependent on the tension in the yarn after passing the said frictionw'ashers for varying the pressure exerted by the fluid actuated means inversely in accordance vvith-=var-iations inthe said tension. I a

3. In a tension regulator fora moving strand of yarn, the combination of :a first friction member, a second friction member'movable toward and from the first frictionmember, fluid actuated means, comprising a-pistonsand a cylinder one of which is .movablerelativelyto the other with the movable one of the :last said elements.

acting on the second friction member to press it toward the first friction member. to engagethe yarn between the said membersa d t er b cause tension in the va nimeans for supplyi fluid to t e id actuate m ansiand m ans,

dependent on the tension in the yarn after passing the said friction members for varying the pressure of the fluid suppliedto the fluid actuQ ated means to so vary theipressure on the second friction member as to maintain the yarntension' substantially constant. I I l. 4. In a tension-regulator for a moving-strand of yarn, the combination of a first friction mem ber, a second frictionimember movable toward and from the first friction mehlberQfluid actuated means comprising .a piston and. ja cylinderone of which is movable rela'tivelyfto the. other with" the movable one of the'la'stfsaid elements acting on the second friction member "to press it toward the first ,fric'tionmemberto"engagethe yarn between the said members and thereby causetension inthe'yarn, means'for supplying fluid vary the pressure on the second friction member asjto maintain the yarn tensionsubstantially constant, and means for varying the action of the tension dependent means to vary the amount of the said substantially constant tension. a 5. In a tension regulator for a moving strand of yarn, the combination of'a supporting element,

a first friction washer carried by the supporting 7 element and rotatable about a vertical axis, fluid ated means and being movable thereby toward the first friction iwasher'jto engage the yarn between the saidfwashers and thereby cause tension in the yarn, means for supplying fluidlunder pressure to the interior of the cylinder, and

means dependenton thetension in the yarn after passing the said trictioln washers forvarying the pressure of, the fluid supplied'to the cylinderto so vary the pressure on, the second friction washer as to maintain the yarntension V substantially constant.

6. In'a tension regulatorfor a moving strand of yarn, the combination of ajsupporting ele' ment, a first friction washer carried by the supporting element, the said Washer being rotatable elet v lv oth sugp r i em nt a t a v rtical axis but being'adjustable relatively to, the

sa d el e toroiate. a uts t l d axis, u actuated means carried by the supporting element and :GQH Pl S I a e t al Pi n, n a ver cal i. er with one of th mm le t c lly relatively toathe. w n. a s c nd f t o wesh rhelow th first irict iw h h i second washer being'rotatable relatively to the supporting element'about the same vertical axis as thefirst washer but being adjustable relatively to the said element to rotate about a tilted axis: and the said second Washer being carried by the vertically movable element of the fluid actuated means and being movable thereby'toward the first friction washerto engage the yarn between the said washers and thereby cause tension in-theyarn, means for supplying fluid under pressure to the interior .of the cylinder, and means dependent on thetension in the yarn after. passing :the'said friction washers for varying the-pressure of the fluid supplied to the cylinder to sovaryithe pressure on the second friction washer as to maintain the yarn tension substantially constant.

- -7. Ina-tension regulator-fora moving strand of yarn, the combination of aasupporting element, two companion friction; washers on, the supporting element rotatable about ;a vertical axis underthe influencevof a, strand of yarn pass.-

ing between them, a vertical piston on the supporting element held against. vertical movement, r

a vertical cylinder closedat the top and enclosing the piston and vertically movable relatively thereto, the said cylinder'gupon upward -move.-'

ment engaging the lower friction washer to move it toward the upper friction washer .so. asv to en-' gage the yarn' between the said: washers and thereby cause tension' in the -yarn' and the said cylinder having an upward extending concentric sleeve on which the lower washer is rotatable and which is engaged by the yarn so that the said sleeve and cylinder are rotated with respect to the piston, means for supplying air under pressure to the interior of the cylinder, and means dependent on the tension in the yarn after passing the said friction washers for varying the pressure of the air supplied to the cylinder to so vary the pressure on the second friction washer as to maintain the yarn tension substantially constant.

8. In a tension regulator for a moving strand of yarn, the combination of means for resisting the movement of the yarn to cause tension therein, fluid pressure actuated means acting on the resisting means to vary the resistance applied thereby to the yarn, a conduit serving to supply fluid under pressure to the fluid pressure actuated means and having a bleed orifice therein, and means dependent on the tension in the yarn after passing the said resisting means for varying the flow of fluid through the bleed orifice to thereby vary the pressure of the fluid supplied to the fluid pressure actuated means so as to maintain the yarn tension substantially constant.

9. In a tension regulator for a moving strand of yarn, the combination of a first friction member, a second friction member movable toward and from the first friction member, fluid pressure actuated means comprising a piston and a cylinder one of which is movable relatively to the other with the movable element acting on the second friction member to press it toward the first friction member to engage the yarn between the said members and thereby cause tension in the yarn, a conduit serving to supply fluid under pressure to the fluid pressure actuated means and having a bleed orifice therein, and means dependent on the tension in the yarn after passing the said friction members for varying the flow of fluid through the bleed orifice to thereby vary the pressure on the second friction member so as to maintain the yarn tension substantially constant.

10. In a. tension regulator for a moving strand of yarn, the combination of means for frictionally engaging the yarn to resist the movement thereof, pneumatically actuated means acting on the friction means to vary the friction applied thereby to the yarn, a conduit serving to supply air under pressure to the pneumatically actuated means and having a bleed orifice therein, means dependent on the tension in the yarn after passing the said friction means for varying the flow of air through the bleed orifice to thereby vary the action of the pneumatically actuated means on the friction means so as to maintain the yarn tension substantially constant, and means for varying the action of the tension dependent means to decrease or increase the amount of bleeding and thereby increase or decrease the tension in the yarn.

11. In a tension regulator unit for a moving strand of yarn, the combination of means for frictionally engaging the yarn to resist the movement thereof and to thereby cause tension therein, pneumatically actuated means acting on the friction means to vary the friction applied thereby to the yarn, an air reservoir within the unit, a conduit serving to supply air under pressure from the reservoir to the pneumatically actuated means and having a bleed orifice therein, and means dependent on the tension-in the yarn after passing the said friction means for varying 12 the flow of air through the bleed orifice to there= by vary the action of the pneumatically actuated means on the friction means so as to maintain the yarn tension substantially constant.

12. In a tension regulator unit for a moving strand of yarn, the combination of means for frictionally engaging the yarn to resist the movement thereof and thereby cause tension therein, pneumatically actuated means acting on the friction means to vary the friction applied thereby to the yarn, an air reservoir within the unit, means for supplying air at a constant rate to the reservoir, a conduit serving to supply air under pressure from the reservoir to the pneumatically actuated means and having a bleed orifice therein, and means dependent on the tension in the yarn after passing the said friction means for varying the flow of air through the bleed orifice to thereby vary the action of the pneumatically actuated means on the friction means so as to maintain the yarn tension substantially constant.

13. A tension regulator for a moving strand of yarn comprising in combination, a resisting means bodily movable in its entirety and engaging the yarn forresisting the movement thereof so as to cause tension therein, the tension in the yarn moving from the resisting means tending to bodily move it in one direction, a constant pressure means. tending to bodily move the resisting means in the opposite direction, the said constant pressure means tending in conjunction with the yarn tension to maintain the resisting means in a position of equilibrium wherein the yarn tension is constant, means associated with the said resisting means for varying the resistance thereof, and means separate from the constant pressure means and dependent on bodily movements of the resisting means out of its said position of equilibrium for causing the said resistance varying means to decrease the resistance of the resistance means when it moves as aforesaid in the direction of yarn movement and to increase the resistance of the said resistance means when it moves as aforesaid in the opposite direction so as to thereby maintain the said yarn tension substantially constant.

14. A tension regulator for a moving strand of yarn comprising in combination, a means bodily movable in its entirety and engaging the yarn for resisting the movement thereof so as to cause tension therein, the tension in the yarn moving from the resisting means tending to bodily move it in one direction, a, constant pressure means tending to bodily move the resisting means in the opposite direction, the said constant pressure means tending in conjunction with the yarn tension to maintain the resisting means in a position of equilibrium wherein the yarn tension is constant, means associated with the said resisting means for varying the resistance thereof, means separate from the constant pressure means and dependent on bodily movements of the resisting means out of its said position of equilibrium for causing the said resistance varying means to decrease the resistance of the resistance means when it moves as aforesaid in the direction of yarn movement and to increase the resistance of the said resistance means when it moves as aforesaid in the opposite direction so as to thereby maintain the said yarn tension substantially constant, and means for changing the force exerted by the constant pressure means to thereby establish a new position of equilibrium ang l tion means in the opposite direction,.means-for guiding the yarn to the friction means in a direction substantially perpendicular to the direc-' tion of bodily movement ofthefriction means so as to avoidany tendency for primary tension in the said yarn to bodily move the friction means, andmeans separatefrom the constant pressure means anddependent on thebodily movements of the friction means under the influence of yarn tension and under the influence of the said con- A stant pressure means for varying the action of the said friction meansso as to maintain the said yarn tension substantially constant.

. 1,6. A, tension regulator for amoving strand of yarn comprising inicombination, a bodily movable friction means engagingv the yarn and resisting the movement thereof so as to cause ten-' sion therein, the saidfriction means being bodily movable in one direction underthe influence of the tension in the yarn-moving therefrom, a con- U stant pressure meansfor bodily moving the friction means in the opposite direction, fluid pressure means separate from the constant. pressure means acting on the friction means to vary the, resistance applied therebyv to the yarn, andv means dependent on bodily movementsof the friction means under the influence of yarn tension and under the influence of the said constant pressure means for causing the said fluid DIES-f sureqmeans to vary the action of the said friction means so as to maintain the said yarn tension substantially constant.

17.. A yarn tension regulator for a moving strand: of yarn comprising, in combination, a bodily movable friction means comprising a first frictionmember and a second friction member movable, toward and from the first friction member, means supporting the said friction means for bodily movement in one direction under the influence of the tension in the yarn moving.

therefrom, a constant pressure means for bodily moving the friction meansin the opposite direction, fluid pressure'meansseparate from the constant pressure means and comprising a piston and a. cylinder oneof which is movable relatively totheother withthe movable element connected with the second friction member to press it toward the first friction member to engage the yarn and cause tension therein, means for supplying'fluid underpressure to the interior of the cylinder, and means dependent onbodily movements of the friction mean under the influence of 1 yarn tension and under the influence of the said-i constant pressure means for causing the said fluid pressure means to vary the actionof the said frictionmeans so as to maintain the said yarn tension substantially constant. 7

18. A tension regulator for a-moving strand of yarn comprising in combination, a friction means engaging the yarn and resisting the movement thereof so as to cause tension therein, means supporting the said friction means for bodily movement in one direction under the influence of the tension in the yarnmoving therefrom, a constant pressure means for bodily moving the friction means in the'opposite direction, a fluid pressure means separate from the constant'pressure means acting on the friction means to vary the resistance applied thereby to the yarn, aconduit serving to supply fluid to thefluid pressure means and having a bleed orifice therein, and means dependent on bodily movements of the friction means under theinfluence of yarn tension and under the influence of the said constant pressure means for varying the flow of fluid through the blee'dorifice to thereby cause the said fluid pressure mean to vary the action of the saidfriction means" so as to maintain the said yarn tension substantially constant. i

19.: A tension: regulator unit for a moving strand of yarn comprising in combination, a fric tion means engaging theyarnand resisting the movement thereof goes to cause tension therein, means supporting the said friction means for bodily movement in one direction under the influence of the tensionin the yarn moving there-z from, aconstant pressure means for bodily moving the friction means in the :opposite direction, a pneum'aticmeans separate from the constant.

pressure means acting on the friction'mean to vary the resistance applied thereby to the yarn, I

an air reservoir Within the unit,means forsup plying air to the reservoir atia constantirate, a conduit serving to supply air from the reservoir to the pneumatic means and having a bleed orilice therein, and means dependent on bodily movements of the friction means under. the me fluence of yarn tension and under the influence of the said constant pressure means for varying the flow of air through the bleed orifice to thereby cause the said pneumatic means to vary the action of the said friction means :so as to'main-i tain the said yarn tension substantially constant.

ing the friction means in the opposite direction,

a pneumatic means separate from the" constant pressure means acting: on the friction means to vary the resistanceapplied thereby to the yarn, a conduit serving to supply air to the pneumatic means and having a bleed orifice therein, an element adjacent the bleed orifice for restricting the flow of air therethrough, and means de-.

pendent on bodily movements of the friction means under the influenceof yarn tension and under the influence of the said constant. pres-: sure means for varying'the distance between the bleed orifice and the fiow restricting elementto vary the flow of air through the. bleedxiorifice to thereby cause the said pneumatic means to vary the action of the said friction means so as to maintain the said yarn tension substantially constant. a r

21. A tensionregulator for a moving strand of yarn'comprising in combination, a friction means for resisting the movement of the yarn to cause:-

tension thereimmeans forsupporting the fric-- tion means forpivotal movement about an axisv spaced from the line of movement of the yarn. from the friction means and perpendicular to a vertical plane'through the said line, the said sup-- porting means permitting the friction means to pivotally move in one direction under the .influ-' ence of the tension in theyarn movingthere-- from, a constant pressure means for pivotally moving the friction means in the opposite direction, and means separate from the constant pressure means and dependent on the pivotal movements of the friction means under the influence of yarn tension and under the influence of the said constant pressure means for varying the action of the said friction means so as to maintain the said yarn tension substantially constant.

22. A tension regulator for a moving strand of yarn comprising in combination, a friction means for resisting the movement of the yarn to cause tension therein, means for supporting the friction means for pivotal movement about an axis spaced from the line of movement of the yarn from the friction means and perpendicular to a vertical planethrough the said line, the said supporting means permitting the friction means to pivotally move in one direction under the influence of the tension in the yarn moving therefrom, a constant pressure means for pivotally moving the friction means in the opposite direction, means associated with the said friction means for varying the friction thereof, means for guiding the yarn to the friction means in a direction substantially parallel to the axis of pivotal movement of the said friction means so as to avoid any tendency for the primary tension in the said yarn to pivotally move the friction means, and means separate from the constant pressure means and dependent on the pivotal movements of the friction means under the influence of yarn tension and under the influence of the said constant pressure means for causing the said friction varying means to decrease the friction of the friction means when it moves as aforesaid in the direction of yarn movement and to increase the friction of the said friction means when it moves as aforesaid in the opposite direction so as to maintain the said yarn tension substantially constant.

23. A tension regulator for a moving strand of yarn comprising in combination, a friction means for resisting the movement of the yarn to cause tension therein, means for supporting the friction means for pivotal movement about an axis spaced from the line of movement of the yarn from the friction means and perpendicular to a vertical plane through the said line, the said supporting means permitting the friction means to pivotally move in one direction under the influence of the tension in the yarn moving therefrom. a constant pressure means for pivotally moving the friction means in the opposite direction, fluid pressure means separate from the constant pressure means and carried by the supporting means and movable with the friction means, the said fluid pressure means acting on the friction means to vary the resistance applied thereby to the yarn, and means dependent on the pivotal movements of the friction means under the influence of yarn tension and under the influence of the said constant pressure means for causing the said fluid pressure means to vary the action of the said friction means so as to maintain the said yarn tension substantially constant.

24. In a tension regulator for a moving strand of yarn, the combination of a friction means bodily movable in its entirety and engaging the yarn for resisting the movement thereof so as to cause tension therein, the said friction means being bodily movable in one direction under the influence of the tension in the yarn moving therefrom, means for applying constant fluid pressure tending to bodily move the friction means in the opposite direction, means associated with the said friction means for varying the friction thereof, and means separate from the constant fluid pressure means and dependent on the bodily movements of the friction means for causing the said friction varying means to decrease the friction of the friction means when it moves as aforesaid in the direction of yarn movement and to increase the friction of the said friction mean when it moves as aforesaid in the opposite direction so as to maintain the said yarn tension substantially constant.

25. In a tension regulator for a moving strand of yarn, the combination of a friction means bodily movable in its entirety and engaging the yarn for resisting the movement thereof so as to cause tension therein, the said friction means being bodily movable in one direction under the influence of the tension in the yarn moving therefrom, a chamber closed by a flexible diaphragm, means for maintaining a constant fluid pressure within the chamber, means connected with the bodily movable friction means and engaging the diaphragm whereby the fluid pressure within the chamber tends to bodily move the friction means in the opposite direction, means associated with the said friction means for varying the friction thereof, and means separate from the constant fluid pressure means and dependent on the bodily movements of the friction means for causing the said friction varying means to decrease the friction of the friction means when it moves as aforesaid in the direction of yarn movement and to increase the friction of the said friction means when it moves as aforesaid in the opposite direction so as to maintain the said yarn tensionsubstantially constant.

26. In a tension regulator for a moving strand of yarn, the combination of a friction means bodily movable in its entirety and engaging the yarn for resisting the movement thereof so as to cause tension therein, the tension in the yarn moving from the friction means tending to move it in one direction, a means for applying normally constant fluid pressure tending to bodily move the friction means in the opposite direction, the said constant fluid pressure means tending in conjunction with the yarn tension to maintain the friction means in a position of equilibrium wherein the yarn tension is constant, means associated with the said friction means for varying the friction thereof, means separate from the constant fluid pressure means and dependent on bodily movements of the friction means out of its said position of equilibrium for causing the said friction varying means to decrease the friction of the friction means when it moves as aforesaid in the direction of yarn movement and to increase the friction of the said friction means when it moves as aforesaid in the opposite direction so as to maintain the said yarn tension substantially constant, and means for changing the pressure exerted by the constant fluid pressure means to thereby establish a new position of equilibrium and thus change the said substantially constant yarn tension.

27. In a tension regulator for a moving strand of yarn, the combination of a bodily movable friction means engaging the yarn and resisting the movement thereof so as to cause tension therein, the said friction means being bodily movable in one direction under the influence of the tension in the yarn moving therefrom, a means a vertical plane therethrough, the said washers and the supporting element being pivotally movable in one direction under the influence of yarn tension, a pneumatic pressure means on the supporting element below the washers and comprising a piston and a cylinder one of which is movable relatively to the other to press the lower washer toward the upper washer and thereby apply frictional resistance to the yarn, a chamber within the housing closed by a flexible diaphragm, means for supplying fluid under pressure to the chamber, means on the supporting element engaging the diaphragm to enable the diaphragm to cause pivotal movement of the supporting element and of the parts carried thereby in the direction opposite to the direction in which they move under the influence of yarn tension, a conduit for supplying air to the pneumatic pressure means, the said conduit having a flexible portion permitting the said pneumatic pressure means to move with the supporting element and the said conduit having a stationary bleed orifice, and means on the supporting element immediately adjacent the bleed orifice for restricting the flow of air therefrom, the said last means being mov- I able away from the orifice to permit increased flow therefrom when the supporting member is moved in one direction by increased yarn tension and the last said means being movable toward the orifice to cause decreased flow therefrom when the supporting member is moved in the opposite direction as the result of decreased yarn tension.

33. The combination in a tension regulator for a moving strand of yarn, of a casing, a supporting element pivoted within the casing for movement about a horizontal axis and projecting therefrom at the top, two friction washers carried by the supporting element at the top thereof above the casing and freely rotatable about a normally vertical axis, the said washers being adapted to receive between them a strand of yarn moving therefrom in a line spaced from the pivotal axis of the supporting element and perpendicular to a vertical plane therethrough, the said washers and the supporting element being pivotally movable in one direction under the influence of yarn tension, a primary tension means carried by the casing and positioned so that the strand of yarn moves therefrom to the friction washers in a direction parallel to the pivotal axis of the supporting element, a pneumatic pressure means on the supporting element below the washers and comprising a piston and a cylinder one of which is movable relatively to the other to press the lower washer toward the upper washer and thereby apply frictional resistance to the yarn, a constant pressure means tending to cause pivotal movement of the supporting element and of the parts carried thereby in the direction opposite to the direction in which they move under the influence of yarn tension, a conduit for supplying air to the pneumatic pressure means, the said conduit having a flexible portion permitting the said pneumatic pressure means to move with the supporting element and the said conduit having a stationary bleed orifice, and means on the supporting element immediately adjacent the bleed orifice for restricting the flow of air therefrom, the said last means being movable away from the orifice to permit increased flow therefrom when the supporting member is moved in one direction by increased yarn tension and the last said means being movable toward the orifice to cause decreased fiow therefrom when the sup- 20 porting member is moved in the opposite direction as the result of decreased yarn tension.

34. The combination in a tension regulator for a moving strand of yarn, of a casing, a supporting element pivoted within the casing for movement about a horizontal axis and projecting therefrom at the top, two friction washers carried by the supporting element at the top thereof above the casing and freely rotatable about a normally vertical axis, the said washers being adapted to receive between them a strand of yarn moving therefrom in a line spaced from the pivotal axis of the supporting element and perpendicular to a vertical plane therethrough, the said washers and the supporting element being pivotally movable in one direction under the influence of yarn tension, a fluid pressure means on the supporting element below the washers and comprising a piston and a cylinder one of which is movable relatively to the other to press the lower washer toward the upper washer and thereby apply frictional resistance to the yarn, a flexible conduit for supplying fluid to the fluid pressure means, a constant pressure means tending to cause pivotal movement of the supporting element and of the parts carried thereby in the direction opposite to that in which they move under the influence of yarn tension, means dependent on the pivotal movements of the friction means under the influence of yarn tension and under the influence of the pneumatic pressure means for causing the fluid pressure means to vary the action of the said friction means so as to maintain the said yam tension substantially constant, and a weight carried by the supporting element at a position near the bottom thereof within the casing and spaced downward from the pivotal axis, the said weight serving to counterbalance the friction washers and other parts carried by the supporting element.

35. The combination in a tension regulator for a moving strand of yarn, of a casing, a. supporting element pivoted within the casing for movement about a horizontal axis and projecting therefrom at the top, two friction washers carried by the supporting element at the top thereof above the casing and freely rotatable about a normally vertical axis, the said washers being adapted to receive between them a strand of yarn moving therefrom in a line spaced from the pivotal axis of the supporting element and perpendicular to a vertical plane therethrough, the said washers and the supporting element being pivotally movable in one direction under the influence of yarn tension, a pneumatic pressure means on the supporting element below the washers and comprising a piston and a cylinder one of which is movable relatively to the other to press the lower washer toward the upper washer and thereby apply frictional resistance to the yarn, a flexible conduit for supplying air to the pneumatic pressure means, a constant pressure means tending to cause pivotal movement of the supporting element and of the parts carried thereby in the direction opposite to that in which they move under the influence of yarn tension, means dependent on the pivotal movements of the friction means under the influence of yarn tension and under the influence of the constant pressure means for causing the pneumatic pressure means to vary the action of the said friction means so as to maintain the said yarn tension substantially constant, and a weight carried by the supporting element at a position near the bottom thereof within the casing and spaced down- 21 ward from thezpivotaleaxis; thesaid weight being adapted to counterbalance. the friction washers and otherparts carried bythe supportingelement and the saidweight beingadjustable outiof its counterbalaricing position.

36. In an apparatus for regulating the tension in a: plurality of moving.- strands of yarn, the combination of a plurality of similar'units for resisting the movements of the respective strands to cause tension therein, each unit including means for maintaining the tension in the correspondin strand of yarn substantially constant and also including fluid pressure operable means for increasing or decreasing the said tension, and

a common means connected with all of the units for simultaneously and uniformly changing the fluid pressure in the fluid pressure operable means of all of the said units to increase or decrease the tension in all of the said strands of yarn simultaneously and uniformly.

37. In an apparatus for regulating the tension in a plurality of moving strands of yarn, the combination of a plurality of similar units for resisting the movement of the respective strands to cause tension therein, each unit including means for maintaining the tension in the corresponding strand of yarn substantially constant and also including fluid pressure operable means additional to the first said means for increasing or decreasing the said tension, a source of fluid under pres sure, a main fluid conduit leading from the said source, branch fluid conduits leading from the main conduit to the several units, means connected in the main fluid conduit for maintaining constant pressure therein and in the branch conduits and in the fluid pressure operable means of the several units, and means for changing the said constant fluid pressure to thereby change the pressure in the fluid pressure operable means of all of the several units simultaneously and uniformly so as to increase or decrease the tension in all of the said strands of yarn simultaneously and uniformly.

38. In an apparatus for regulatin the tension in a plurality of moving strands of yarn, the combination of a plurality of units for regulating the tension in the respective strands of yarn, each unit including means for frictionally engaging the yarn to resist the movement thereof and thereby cause tension therein, including an operating fluid pressure means acting on the friction means to vary the friction applied thereby to the yarn, including means dependent on the tension in the yarn after passing the friction means for causing the operating fluid pressure means to so vary the action of the friction means as to maintain the said yarn tension substantially constant and including a controlling means dependent on fluid pressure for adjusting the action of the said operating fluid pressure means to provide increased or decreased tension, and a common means connected with all of the units for simultaneously and uniformly changing the fluid pressure in the said controlling means of all of the units to increase or decrease the tension in all of the said strands of yarn simultaneously and uniformly.

39. In an apparatus for regulating the tension in a plurality of moving strands of yarn, the combination of a plurality of units for regulating the tension in the respective strands of yarn, each unit including means for frictionally engaging the yarn to resist the movement thereof and thereby cause tension therein, including an operating fluid pressure means acting on the friction means to vary the friction applied thereby to 1the yarn inc1uding means dependent on :the-,-ten- .sion; in the Jam: after Passingthe :friction means foncau sing theioperating fluidpressure means to so vary:-the .action;,ofthe friction means as to maintaimthasaid yarntension substantially constant andincluding :a controlling-means dependent on;fluid;pres sure foradjustin the ,action of the saidloperatingi-fluid pressure means to provide the said operating fluidmressure means of the several .,units,, a ,main controlling conduit leading'from' the said source, branch conduits leading from the said main controlling cond'uit'to" the said fluid pressure controlling means of the several units, means connected in the main controlling conduit for maintaining constant pressure therein and in the corresponding branch conduits and in the said controlling fluid pressure means of the several units, and means for changing the last said constant pressure to thereby change the pressure in the said controlling fluid pressure means of the several units so as to vary the tension in all of the strands of yarn simultaneously and uniformly.

' 40. In an apparatus for regulating the tension in a plurality of moving strands of yarn, the combination of a plurality of units for regulating the tension in the respective strands of yarn, each unit including means for frictionally engaging the yarn to resist movement thereof so as to cause tension therein which friction means is bodily movable in its entirely in one direction under the influence of the tension in the yarn moving therefrom, including a constant fluid pressure means for bodily moving the friction means in the opposite direction, including means associated with the friction means for varying the friction thereof and also including means separate from the constant fluid pressure means and dependent on bodily movements of the friction-means for causing the said friction varying means to decrease the friction of the friction means when it moves as aforesaid in the direction of yarn movement and to increase the friction of the said friction means when it moves as aforesaid in the opposite direction so as to maintain the said yarn tension substantially constant, and a common connected with all of the units for simultaneously and uniformly changing the pressure in the said constant fluid pressure means of all of the units to increase or decrease the tension in all of the said strands of yarn simultaneously and uniformly.

41. In an apparatus for regulating the tension in a plurality of moving strands of yarn, the combination of a plurality of units for regulating the tension in the respective strands of yarn, each unit including means for frictionally engaging the yarn to resist the movement thereof and thereby cause tension therein which friction means is bodily movable in one direction, under the influence of the tension in the yarn moving therefrom, including controlling means dependent on constant fluid pressure for bodily moving the friction means in the opposite direction, including an operating fluid pressure means separate from the constant fluid pressure controlling means and acting on the friction means to vary the friction applied thereby to the yarn and including means dependent on bodily movements of the friction means under the influence of yarn tension and under the influence of the said con- 23 stant fluid pressure controlling means for causing the operating fluid pressure means to vary the action of the said friction means so as to maintain the said tension substantially constant, and

Number a common means connected with all of the units 5 for simultaneously and uniformly changing the pressure in the said constant pressure controlling means of all of the said units to increase or decrease the tension in all of the said strands of yarn simultaneously and uniformly,

PAUL J. CAMPBELL.

REFERENCES CITED The following references are of record in the file of this patent:

Number 24 UNITED STATES PATENTS Name 7 Date Murdock Nov. 27, 1923 Carpenter May 26, 1925 FOREIGN PATENTS Country Date Great Britain Apr. 9, 1931 Great Britain June 18, 1931

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