US2609006A - Letoff device for textile machines - Google Patents

Description

Sept. 2, 1952 w. LORD 2,609,006

LETOFF' DEVICE FOR TEXTILE MACHINES Filed April 2a, 1948 4 Sheets-Sheet 1 Os Q l\ q;

Inventor m MILAN-09.1.0110

8 Mi a y Attorm Sept. 2, 1952 w. LORD LETOFF pEvIcE FOR TEXTILE MACHINES 4 Sheets-Shet 2 Filed April 28. 1948 III! I IIIIL Inventor Wu. FRED Lam) M M B m w. I A

W. LORD LETOFF DEVICE FOR TEXTILE MACHINES Sept. 2, 1952 4 SheetsQ-Sheet :5

Filed April 28, 1948 DH MQLF m mm DMA ME Sept. 2, 1952 w. LORD 2,509,006

' LETOFF DEVICE FOR TEXTILE MACHINES v Filed April 28, 1948 4' Sheets-Sheet! 2 29a a J 30 7 X Inventor WILFRED LORD BYWZ- y A homey Patented Sept. 2, 1952 UNITED T S: P -Enr- OFFICE I 2,609,006 LETOFF DEVICE FOR TEXTILE MACHINES.

Wilfred-Lord, Kighley, England Application April 28, 1948,.Serial-No. :zasss In GreatBritain April 9', 1947 on to which'a threador the like is'being wound,

inorder to tension correctly the said thread or the'like.

In order that the invention may be the more 9 claims.- (01. 139-408) clearly understood, a let-off device in accordance in.sucha way'as to maintain the tension of the thread-constant. Inthe said drawings:

Figure l is a side elevation of the relevan portion of the loom with some of the parts omitted;

Figure 2 is a view-to'a larger scale of a-portion of Figure 1 shown partly" in section and-with the said parts in place;

Figure-3 is an end "elevation-viewed from the left of Figurez and shown partly in'section;

Figuret-is'a 'sectionon line lV-IV of Figure 1;

Figure sis a section on. line V-V of Figure 1;

Figure 6 is a view of a portion of Figure 1 shown at "a different operative position.

Referring to the drawingsthe reference numeral I .de'signates 'the-warp beam and therefor-- 'enc'e numeral 2 the thread. A'main lever 3 is provided which'rotates about the axis of a horizontal 'shaf't 4 which is parallel to the axis of the warp beam 1. This lever carries a weight 5, and, as will be hereinafter more particularly described, the lever and the warp beam arecoupled togetherbyatransmission' gear train so that the moment ofthe lever and weight about its axis 'applie's'tensi'on to the thread. Moreover this transmission gear train includes in it a differential-i'gear train 6 and means are provided for automatically adj-ustingsaid differential gear in 2 ,Thus the tension of'the unwinding thread will depend on the gravity bias of the lever 3, but the latter will remain approximately stationary. In like manner when it is desired to rewind some of'the thread {on to the warp'beam l, the thread .is paid back to the warp beam and the latter will'rotate, under the gravity bias of the lever, in the direction for rewinding, thethread. The lever will tend to rotate-downwardlyunder itsgravity bias, but again the differential gear will be operated to maintainsaid lever at its normal position. .Thus the tension of the windingthread will depend on the gravity bias ,of the lever, but-the latter willremain approximately stationary.

Finallythe position of the weight 5 along said main lever '3 is varied according to variations of the radius-at'which-the thread 2 is wound off or onto the warp beam I, in such a direction that it approaches the axis-of the lever-as the said radius diminishes, and it will therefore be seen that the moment hi the thread tension about the axis of the warp beam-will diminish as the radius diminishes. The design is .such that these two diminutions conform so that'the thread-tension remains constant.

Describing now the transmission gear train coupling the warp beam 1 and the lever 3, the differential gear train "-6 in said gear train 1 comprises two bevel-gears 1 and B rotatable about the axis of the shaft-4 and an intermediate bevel gear 9 inmesh'with bothgearsl and 8 and rotatable'about an=axisat-rightangles to said shaft 4, said intermediatebevel gear 9" being carried by a casing 10 which encloses the three bevel gears and is itself rotatableiabout theaxis of said shaft 4. The bevel gear 8 is fast with the lever 3, and the bevel gearl is'fast withagear II which is inmeshwith-a-geann which is in mesh with such a way-that the lever 3 is maintained-within limits always-at a normal positionfairly close to the horizontal. Thus, when the thread 2 is being drawn off the warp beam l the rotationof the warp beam will tend to rotate the lever 3 upwardly in opposition to its gravity bias, but the difierentialgear 6 will automatically be'oper ated'tomaintain'said lever at'its normal position.

a 'gear' l3 which is "fast'with the warp-beam i. This consti-tutes' the transmission train and it will be seen that, assuming that-the casing IU of the differential gear 6 is stationary, clockwise rotation of the-warpbeam (according to Figures 1 and 2) caused by drawing off thread will cause counterclockwise or upward rotation of the lever Sagainstthe bias of the weight 5, and clockwise or-downward rotation of 'the' lever under the bias of the weight, permitted'bythe payingback of'the'th-read to the warp beamwill cause" counterclockwise rotation ofthe warp beam for taking'up the thread.

For adjusting the differential gear,train-Bkfor maintaining the leverjat'the normal position, the casing ll] of said 'differential gear train has integral with it a worm wheel l4 which is in mesh with a worm l5 fast on a worm shaft l6. For returning the lever 3 when it tends to be moved upwardly by the drawing off of the thread from the warp, a sleeve I1 is mounted so as to rotate freely on said worm shaft, and said sleeve carries a pawl 8 which is biased by means of a spring 96 into engagement with a ratchet wheel l9 which" is fast on said w0rrn.-shaft.- So long as the loom is running said sleeve H and therefore the pawl I8 is oscillated, as will hereinafter of the lever 3, said lever 3 has an arm 21 rigid with it and projecting downwardly from it at right angles to it and radially with respect to the shaft 4. This arm 21 at its extremity is pivotally connected to one end of an approximately horizontal link 28. The other end of said link is pivotally connected to the upper end of a link appear, about the axis of the worm shaft, and 1 the direction in which the pawl engages the ratchet wheel I9 is such as to rotate said ratchet wheel and therefore the worm shaft l6, the worm I5, the worm wheel I4 and casing IU of the differential gearing in the direction for rotating the lever 3 in a, downward direction. A shield 20, however, is provided, carried by a second sleeve 2| which is also freely rotatable on the worm shaft, and means are provided, as will hereinafter appear, whereby, so long as the lever 3 is within the limits of its normal position, said sleeve 2| occupies a position such that the shield. 20 is interposed between the pawl ,|8 and the ratchet wheel |9. Under these circumstances therefore the pawl! 8 oscillates on the surfaceof the shield 20 without engaging the ratchet wheel I9. But when the lever 3' rises above the limits of its normal position the sleeve 2| is rotated so asto expose the ratchet wheel H! to the pawl I8, and

'said ratchet wheel is therefore rotated step by step so as to move the lever down and restore it to its normal position. According to whether the lever 3 is-raised a lessor a greater distance above the limits of its normal position, the exposure of the ratchet wheel l9 to thepawl l8 iseffected to the extent of a less or greater number of teeth, and therefore the steps of rotation of the pawl are smaller or'greaterand the rate of returning the lever to its normal position is smaller or greater.

For returning the lever '3' when it tends to move downwardly during re-winding of; the thread onto the warp, a sleeve 22 is mounted'so as to rotate freely on the worm shaft, andsaid sleeve carries a pawl 23 which is biased by'inea'ns of a spring 91 into engagement with a ratchet wheel 24 which is fast on said worm' shaft. 50 long as'the thread is being paid back to the warp, said sleeve 22-, and therefore the pawl 23 is oscillated, as will hereinafter appear, about the axis of the worm shaft and the direction in which said pawl engages said ratchet wheel is such as to rotate said ratchet wheel in the' direction for rotating the lever 3 in an upward direction. A shield 25, however, is provided, carried'by a sleeve 26-which is also freely rotatable on the'worm shaft, and means are provided, as willhereinafter appear, whereby, so long as the lever, 3 is within the limits of its normal position, said sleeve 26 occupies a position such that the shield 25 is interposed'between the pawl 23 and the ratchet'wheel 24, so that no movement is transmitted to the ratchet wheel. When, however, the lever falls below the limits of its normal position the sleeve 26 is rotated so as to expose the ratchet wheel 24 to the pawl 23, and said ratchet wheel is therefore rotated 50 as to move the lever .up and'restore it to its normal position; As in'the case when the lever is rotated downwardly, the rate of upward rotation varies according to the distance the lever hasmoved below the limits of its normal position.

For shifting the two sleeves 2| and 26 and their shields 20 and 25, according to. the movement 29a whose lower end is pivoted to a fixed point 30a and a second link 28a couples theupper end of said link 29a to the lower end of a link 29 whose upper end is pivoted to a fixed point 30.

-It will thus be seen that the link 28a can move left or right in a path determined by the links 29 and 29a.

Said link 28a at its right hand end is pivoted to the upper end of a link 3| whose lower end is pivoted at 32 to the left hand end of a link 33 whose right hand end is pivoted to a fixed point 34. Said link 23a, at its left hand end is pivoted to the lower end of a link 35 Whose upper end is pivoted at 36 to the right hand end of a link 37 whose left hand end is pivoted to a fixed point 36.

The sleeve 2| has a lug 39 projecting from it, and this lug is coupled, by means of a link 40, to the point of, connection 32 of the links 3| and 33. The sleeve 26 has a lug 4| projecting from it and this lug is coupled, by means of a link 42 to the point of connection 36 of the links 35 and 31.

It will readily be seen that the links are so arranged that, when the lever 3 is moved upwards the link28 will move to the right. This will cause the point 32; and therefore the'link 40 and the lug 39 to move upwards, causing the sleeve 2| and shield 20 to rotate counterclockwise (according to Figure 5) The teeth of the ratchet wheel 19 will therefore be exposed to the pawl I8, and the lever 3 will accordingly be adjusted down wardly and restorted to its normal position. During thismovement the point 36 and therefore the link 42 and the lug 4| will move only'very slightly.

When the lever 3 is moved downwards the link 28 is moved to the left. This causes the point 36 and-therefore the link 42 and the lug 41 to be moved downwards, thereby rotating the sleeve 26 and shield 25 clockwise and exposing the teeth of the ratchet wheel 24 to the pawl 23. The lever 3 will accordingly be'adjusted upwardly by oscillation of the pawl 23. During this movement the point 32 moves only very slightly.

For causing the sleeve I and therefore the pawl l8 to oscillate about the axis of the shaft l6, so long as the loom is in operation, a flange 43 is bolted to a wheel 44. This wheel should be visualized as one of the several wheels which rotate while the loom is in operation; This flange has an eccentric pin 45 mounted on it which is connected to the upper end of a link 46 whose lower end is pivotally connected to one end of a rocking lever 41 which rocks about a fixed shaft 48 between its ends. The other end of said rocking lever is pivotally connected to the lower end of a link 49 whose upper end is pivotally connected to a lug 50 which is integral with said sleeve Therefore as the wheel 44 rotates and the pin '45 moves in the path of a circle, the link 46 moves up and down, and therefore the link 49 moves up and down and the lug 50 together with the sleeve l1 and the pawl I8 oscillate about the axis of the shaft I6. I f Before describing the mechanism for causing the sleeve 22 and the pawl 23 to oscillate about the axis of the shaft |6, so long as the thread is being payed back to the warp beam it is neces-,

mechanism don-making up: :(the; wotenzclothiim.

Thus-:the clothrafteriweavingttis wonnd-iontato-zaz" pea-rain such a" way ;t-h'at,ior each-complete; recip rocation-iof thellaygswordathe pawlmalteseacom-e pletearzreciprocation and the, ratchet; wheel-; 53'

is-rotated through one: tooth spacer. Elie-ratchet; wheel soperates:rgearing, notshown, whichAir-lime a friction roller 55 in engagement withetharoller; Iain such-away that *saidclothr is pulledethrough and ion to-- said 1 roller- :151 ran-equal length. beingpulledthroughrat-each:picksa ,7 .To prevent retrograde-movement oiithe-ratchet wheel-:53,- a.paw1,56=..-is, provided mounted m1 one end I of- -a rocking arm 51 -.whichpis pivoted{at 58, to .a :fixed' pcintrzbetween its.:ends.-- This rocking, arm 1-51; is normallypositioned so that the "pawl- 56-engages.the-..teethaof said ,ratchetewheel, rand said p awl e iseresilientlyriyieldablezrelative -toi said rocking arm so .rthat' .the-. ratchet-iteeth can ride. past-it-butcannot return." 1

saidsrooking arm -51,--at; its .-endt.-remote from-M the-pawl- 56 .-is ;formed.. so :as ftocpr ovida a, second. pawl. 59-, the: arrangementubeing such ;that. said. rockingrarm Bleandits two .pawls =56 andi59 form an-rescapement device so-nthat assuming thepawl,

52 to be voutvofr engagement -..with..,. the ratchet.

wheel, oscillation of .saidrocking armtabout-r its pivot lpoint -58:- :wi l1 ,permit. .the lratchetgwheel to rotateinaretrograde manner1i..e counterclocke wise according to Figure- 1)wtorthe.extentptone;

toothforeaoh to-and-fro-oscillation of ."said rockingrarmh-x V I When therefore .it-is wishedto pay .b'ack some; of the thread Z-to the warp abeam I, .theeloomiisi stopped and the. pawl,: 52.. disengagedlfromw the ratchet wheel, and the rocking, arm is =oscil-L lated tmand-fro ab-Y means of ta'thandylever 6 IL'to which-Hit is connected as will hereinafter appear-,1 andflthe warp; beamawilllbeifree to .wind back/thee thread t-stepl-byestep.

To cause thesleeve. 22 landhpaw l lzl il te lo soillatet.

so long; as-"the'thr eadlis .being payed back in this, way' the hand. lever fiflfis, connected to-said sleeve 2-2.- by means -of a Bowden cahleifi l} ,Askwillfbe clear fromfithevdrawing. said sleeve 1 22' is .formed. with as lug 62f. whichaactually .carries the ."pawlr 23-:a'nd said-cablefi his connected to apcint. 6310f said lug. sorthat, when said. cable is t tensione d,; that is; onwmovementlofjthe leiieriillto the right.

for initiating ;a to-andefro movement, -.the sleeve.

22mandepawl1 23 .are moved 1, counterclockwise,

(according to Figure A)". When the cablefil' is relaxed by return movement "of"theelevertfifljto the. left .for completing a-to-and-fro, .movement,

the-sleeve 22'and9awl23lare permitted .tOreturn clockwise under .the influence, of ,ajt'ension' spring 64 .connected "between said, iugisrano a fixec; point. t. Thusthepawlfzt is oscillated so'lon'g as the threads are being payed? back tothetwarpj beam this connection reference is ",made'j tof the previous description explaining howfshieldi 25"i's' mo'vedfaccoi'ding to the position of lever'13' to permit pawl .123, to operate or not;

For; lifting ,the z pawl 52, clear of, the ratchet:

wheel\"53,.j asimple .overrcentregrelease, device is provided comprising a release lever. pivotally mounted between -its ends at point a: and carry ing atrone end' a-pinefifia located underneath butnot normally'in2contact withosaid-lpawle 52a The other rend v:ofi said lever 1-65 is reduced at 1 6} and passes through;ani-aperture imthe free-rendhoftan:1earm';:.68=:;which:rotates: about: a fixed :point :69? andris; rigid iwithizana; operating. handle 1.11 Y

which'xit israddDtEd-,to-"gbe rotated-s A spring I; coilelclion' .thereducedendfil or the lever 65 is n;

compression between the end offthearm-BBnand:

a :sshbuldenofltfiaid; link, 61;, and "it =will-be clear; from 'Ythe-I- drawing that an ever-centre necha nismvisisconstituted whereby; when the han e 3 is pulled down to the:pcsiticnshowm'the; lever-.55;

1' willisnap'iorthe ptositiqniiat which t l i 5611115 downt'as shown and:;pe1-mits vthe pawl 52' riZQr engageithe ratchetwheel 53. Whensaid handle- 1Q; isiliit'edto; the-upzposition, the lever SSH-will snap toaawposlti'on at-which; the pin- 6 to ;is raised and ratchet: wheel. Thequpwardz: and, 1 downward movementsnfrsaidlever 65 are limited bya'fixed,

blagketftfiszi Describing, lnow. the jconnectionbetween -a lay f swordfifl and-the pawl :52;- said pawlilispivotal ly mounted at :1 Z to an intermediate point of. a lever 1:13 whichis piyotally mounted, at itsupper end, at a; fix,ed point Said lever 3 .'istorte d with: arlongitudinaltslot" 15;;and in-thisslot ta-pin-l rockingtjar-m ztil has -rigi,d;;;with it, and-radia with respectgto the :pivot ppint158- of {said rocking-Vanni; awshort arm.;-Hl- :Aglillkfifl connects ;the ;--extr en1i;, tiesxaof the ltwo arms 8 and '|9-.-- It; will be-clear fromzthedrawing?thatthe'erm 1B: and: the; 8i) formwa'rtogglewvhich', whenthe leper fi s; moved.;t lilihflfil'ight o ,;the;po sition show i o'i uretris bent and::thegarm;1 9;;is lowered and the rocking arm: 51wis-:rotated:toithe positionat chq tion showmintFigura-l; the toggle l8 8 Q straight ens tand' lifts the arms-1B; and thereby rotates, he. rocking; armzr5l 1to the position; at -;which; the pa 1;; 5Ggsengages' zthe r-ratchetqwheel; 53 which jis athe position: usedv when; the. :loormis zweaving It willibe seen that the Bowdellccable-fil gon nected :to "the point 1 of connection =.0f-. thetoggle;- links-SENSE? t if Describinganow the-meanShkWhE h weleht 511s; adjusted alongtheimainleyer .3 as the radius 1 the axial :Qfisaid lever;,:; saidxweis tfi I is main-:- tained, qagainstthus-running towards the axisoil saictuleyer by; meanSf-Of a;rfl exible1lead,82 whicii passes irom said weiehtt and: roundiajpullew at: the free extremity-pf- SaidElGYBl; then parallel ztot said lever to and;.under:,a:pulley 84mounted onttha shaft 4 about which" said levenapivotszthemto:and, round a pulley 85, then back andlground said mi r: 84 and nall -.-i e' mi t wot an ora e .8

lfhe pulley, 8 5 t: and :the; anchorage; point; 385;;a1te; moun n n m: 811 wh h is li s ton a r tatable: aft: 8 wh h :h p i h rarm 9; havin at its r ndea=ro1l Which-bears onzethe surfiace-z ofethe vreel of: thread "being" unwound or: wound LOlIr the warp beam I,- the arrangementbeing such that, as the radius of 'thethread diminishes or increases the pulley 85 and anchorage point 86 move so as to permit the weight to run further down the main lever 3, orto draw said weight further up said main lever. The roller 90 which bears on the surface of the reel only exerts a very light pressure which isquite insuflici'ent to cause any entanglement of the thread. 7

It willhave been understood thatwhen the main l'ever3 is at a position within its normal limits both the pawls I8 and 2-3 will be fully maintained but of engagement with their ratchet wheels l9 and 24 by means of the shields 20 and 25 and that in no circumstances can both pawls be permitted to engage their ratchet wheels at the same time. The worm shaft l6 has a handle 9| rigidly mounted on it for enabling it to be rotated at will. This enables the warp beam to be turned by hand when the loom is stopped and is useful when fitting new warps.

Describing now certain constructional details of the apparatus as best shown in Figure 3: for securing the main lever 3 to the bevel gear 8, said lever is bolted to a bracket 92 and said bracket has an integral lug which is formed witha boss 93 which surrounds and is keyed to an elongated sleeve 94 integral with said bevel gear 8. The arm 21 is mounted on this bracket 92 as will be clear from the drawing. V

The bevel gear 1 is also formed with an elongated sleeve 95 on which is keyed the gear I I.

The casing in is rotatably mounted on the two sleeves 94 and 95' as will be clears "The weight 5 is variable 'andis made up'of pieces which fit into a frame. The degree of weight will'vary with diiferent materials "and length'of the warp, but when the weight is establi'shed with a new warp' beam it does not require altering until after the warpa-beam is empty- "The nature of the fixed basic structure on which'the parts heretofore described are mounted.

forms'no part of theinvention and is deemed to be 'sufliciently clear' from' the drawing,

' Itwill have been understood that in ordinary usefthe' thread 2 is'continuouslydrawn ofi the warp'beam'.' The needfor'paying the thread backt'o-the'warp beam 'is usually only necessary when faults develop in the woven'fabric and this op eration usually proceeds for a'short space only:

Dining this operation it is desirable that the length of cloth unwound shall be under'close control and this is achieved very satisfactorily by theescapement mechanism heretofore described, since tliis escapem'ent mechanism'enables the number of ratchet teeth by which'the material is paid back to be counted, if necessary by means of a counting mechanism. 'Thus the number of picks of weft threads corresponding to the length of fabric unwound, is accurately established and after an equivalent number -'of :weft threads are unpicked, the last remaining weft thread will :be'- correctly disposed-to the be'ating' up motion', and thick or thin places in the fabric will be obviated;

It has been found beneficiatto provide anti friction bearings for the bevelgears I, 8 and 9, the'ca'sing l0, the'gear I Z' andthe warp bear n in order to overcome static friction. What is'claimedis:

. In a warp'let-Ofi mechanism, a device for re -win'ding a limited l'engthfof'warp on'a'warp beam at predetermined tension, thesaid-device comprising a given element, biasing means biasin'g'said given'element in a given direction, trans-- mission means between said given element and" 2, In a warp let-off mechanisma device for rewinding a limited length of warp on a warp beam at predetermined tension, the said device comprising a given direction, transmission means between said given element and said beam, whereby said biasing'means bias said beam to rotate in the direction for winding said thread thereon, said transmission means comprising-a rotatable element adapted, upon rotation, to give said given elementa component of movement in the direction opposite to said given direction, a ratchet wheel whose rotation effects rotation of said rotatable element, a pawl for said ratchet wheel adapted to be reciprocated with a constant stroke, and means whereby the distance over which said pawl engages said ratchet wheel at each stroke increases or diminishes as said given element moves in said given direction or returns in the opposite direction, whereby said given element remains substantially stationary despite the continuing rotation of'said beam under the influence of said biasing means.

3. In a warp let-off mechanism, a device for re-winding a limited length of warp on a warp beam at predetermined tension, the said device comprising a given direction, transmission means between said given element and said beam, whereby said biasing means bias said beam to rotate in the direction for winding said thread thereon, said transmission means comprising a rotatable element adapted, upon rotation, to give said given element a component of movement in the direction opposite to said given direction, a ratchet Wheel whose rotation effects rotation of said rotatable element, a pawl for said ratchet wheel, hand-operated means for reciprocating said pawl continuously with a constant stroke, and means whereby the distance over which said pawl engages said ratchet wheel at each stroke increases or diminishes as said given element moves in said given direction or returnsin the opposite direction,.whereby said given element remains substantially stationary despite the continuing rotation of said beam under the influence of said biasing means. I

4. In a textile machine, a device for alternatively exercising a drag on the rotation of a beam whichis rotatedby the drawing of a thread therefrom, andjthereby maintaining said thread at agiven tension, or rotating said beam for windingsaid thread thereon at a given tension, comprisinga given element, biasing means bias-. ing said given element in a given direction, transmission means ,between said given element and said beam,vwhe'reby said biasing means bias said beam to rotate in opposition to the tension of said thread, regulating'means, whereby, in response to said given element moving in opposijusted so as togive said given element'a combiasing means.

H In txtilemachinei vice for'falternat'ively' exercising-adragonth rotation'ofabeam *which' is rotated by the-drawing of a thread therefrom, and; thereby maintaining said thread at a .given tension, or rotating said beam for windingsaid thread thereon at a given tension, comprising a "givenelement'fbia'sing means biasingtsaid given element in a givendirecti'on,transmission meansbetween said"given elementand said bea'mywh'ereby said biasing" means bias said beam to rotate in opposition to the tension of said thread, said transmission means comprising a rotatable element adapted, upon rotation in one direction, to give said given element a component of movement in saidgiven direction, and, upon rotation in the other direction, to give said given element a component of movement in the direction opposite to said given direction, a first ratchet wheel whose rotation effects rotation of said rotatable element in said one direction, a first pawl for said first ratchet wheel adapted to be reciprocated with a constant stroke, means whereby the distance over which said first pawl engages said first ratchet wheel increases or decreases according as said given element moves in the direction opposite to said given direction or returns in said given direction, whereby said given element remains substantially stationary despite continuing rotation of said beam under the influence of said tension, a second ratchet wheel whose rotation effects rotation of said rotatable element in said other direction, a second pawl for said second ratchet wheel adapted to be reciprocated with a constant stroke, means whereby the distance over which said second pawl engages said second ratchet wheel increases or decreases according as said given element moves in said given direction or returns in the opposite direction, whereby said given element remains substantially stationary despite continuing rotation of said beam, under the influence of said biasing means, in opposition to said tension.

6. In a textile machine, a device for alternatively exercising a drag on the rotation of a beam by the drawing of a thread therefrom, and thereby maintaining said thread at a given tension, or rotating said beam for re-winding said thread thereon at a given tension, comprising a given element, biasing means biasing said given element in a given direction, transmission means between said given element and said beam, whereby said biasing means biases said warp beam to rotate in opposition to the tension of said thread, said transmission means comprising a rotatable element adapted, upon rotation in one direction, to give said given element a component of movement in said given direction, and, upon rotation in the other direction, to give said given element a component of movement in the 10 direction opposite to said givendirection, a first ra chet wheel whose rotation effects rotation of said rot'atable element in said one direction, a "first pawl for -said first ratchetwheel; means driven from the; machine mechanism adapted-to reciprocatesaidfirst pawl with 'a constant stroke, rneans whereby' the distance over which'sai'd first paw-l engages said first ratchet wheel increases or decreases aecording -towhether-said given elem 'nt moves I in *the direction oppositeto 'said 'gi eri direction or returns in said'g-ivendirection,

wh'ereby' said' given eiement remains substantiallystationary F despite-continuing rotation of said-beam under -the infiuence of the 'tension of the thread, -a second ratchet wheel whose-rotaticn jeffects'rotation ofsaid rotatable elementin said other dire'etion =a second paw-l forsaid second atchet wheel, 'hand opera'ted means: where'- by sa second-pawl is' adapted to be reciprocated wit -a-coiistant stroke, means whereby thedis- 'tahc'e ever wmen said second-pawlfengages said second ratchet wheel increases or decreases according to whether "said given element moves in said given"di-rection or returns in the-opposite direction} whereby-said given elementremains substantially stationary despite continuing rotation of said beam, under the influence of said biasing means, in opposition to the tension of the thread.

7. In a textile machine, a device for exercising a drag on the rotation of a beam by the drawing of a thread therefrom, and thereby maintaining said thread at a given tension, comprising a first gear wheel, biasing means biasing said first gear wheel to rotate in a given direction, a second gear wheel, coaxial with said first gear wheel and adapted to be rotated by rotation of said beam, an intermediate gear wheel in mesh with both said first and second gear wheels, whereby, when the axis of said intermediate gear wheel is stationary, rotation of said beam by the unwinding of said thread therefrom effects rotation of said first gear wheel in the direction opposite to said given direction, and means whereby, in response to such rotation of said first gear wheel, the axis of said intermediate gear wheel is moved around the axis of said first and second gear wheels so as to give said first gear wheel a component of rotation in said given direction, whereby said first gear wheel remains substantially stationary despite the continued rotation of said beam.

8. In a textile machine, a device for exercising a drag on the rotation of a beam by the drawing of a thread therefrom, and thereby maintaining said thread at a given tension, comprising a lever, a weight mounted on said lever and biasing it to rotate about its axis in a given direction, transmission means between said lever and said beam, whereby the tension of said thread is opposed to the bias of said lever and rotation of said beam by the unwinding of said thread gives said lever a component of rotation in the direction opposite to said given direction, regulating means whereby, in response to rotation of said lever in the direction opposite to said given direction, said transmission means are adjusted so as to give said lever a component of rotation in said given direction, whereby said lever remains substantially stationary despite the continued rotation of said beam, and means whereby said weight is adapted to be moved along said lever so as to increase or diminish the leverage according as the diameter of the thread wound on the beam is greater or less, whereby the tension of the thread is maintained constant.

9. In a textile machine, a device for exercising a drag on the rotation of a beam by the drawing of a thread therefrom, and thereby maintaining said thread at a given tension, comprising a lever, a weight mounted on said lever and biasing it to rotate about its axis in a given direction, transmission means between said lever and said beam, whereby the tension of said thread is opposed to the bias of said lever and rotation of said beam by the unwinding of said thread gives said lever a component of rotation in the direction opposite to said given direction, regulatingmeans whereby, in response to rotation of saidlever in the direction Opposite to said given direction, said transmission means are adjusted so as to give said lever a component of rotation in said given direction, whereby said lever remains substantially stationary despite the continued rotation of said beam, the position at which said lever remains substantially stationary being a position inclined to the horizontal whereby said weight tends to move by gravity along said lever in one direction, and means whereby said weight is retained against such movement at a limiting position which depends on the di- 12 ameter of the thread wound on the beam, so that the leverage exercisedby said weight varies according to said diameter, whereby the tension of the threadis maintainedconstant.

WILFRED LORD,

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

UNITED STATES PATENTS Number Name I Date 1,053,333 Weissenborn Feb. 18, 1913 1,463,966 Northrop Aug. 7, 1923 1,722,856 Payne July 30, 1929 1,729,130 Seymour et al Sept. 24, 1929 1,754,196 Draper Apr. 8, 1930 2,350,954 Brown June 6, 1944 I FOREIGN PATENTS 1 Number Country Date 7,707 Switzerland Dec. 11, 1893 335,140 Great Britain Sept. 18, 1930 398,629 Germany July 12, 1924 Germany June 8, 1925

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