claim,ed: l.. The method of detecting slubs in yarn which comprises passing@yarn over-an orifice, detecting changes in im-pedance to fluid flow.tlirough the orifice occasioned by,changes in the diameter@@of yarn, an arresting the travel of the @arn @a @su detent 7- the d

7 when the detected impedance exceeds .9, predetermined value. 2. The method of detecting slubs in yarn which comprises supplying air under pressure through a restricted passage to a chamber from which it may escape through an orifice to the atmosphere, passing yarn ov@er the orifice to vary the pressure in the chamber in accordance with variations in the diameter of the yarn, and arresting the travel of the yarn when the pressure in the chamber exceeds a predetermined value. 3. A device for detecting slubs in yarn comprising, in combination an element having a chamber therein and provided with restricted inlet and outlet passagos for compressible fluid communicating with said chamber, said outlet passage terminating on the external surface of said element for passage of yarn thereover, a pressure responsive member having a face exposed to the pressure in said chamber, a mechanism adapted when actuated to arrest the travel of yarn and means controlled by said pressure responsive member for actuating said niechanism when the pressure in said chamber exceeds a predetermined va,lue corresponding to a predetermined increase in the diameter of yarn passing over the surface of said element. 4. The device according to claim 3 wherein the outlet passage terminates in a gro6ve in the external surface of said element, the groove serving to guide the yarn in its passage over the surface of the element ' 5. The device according to claim 3 wherein said element includes at least one other outlet passage and means whereby the connection between said first mentioned outlet passage and said chamber may be broken and said other outlet passage connected to said chamber, said other outlet passage when connected with said chamber terminating on the external surface of the element for passage of yarn thereover. 6. The device according to claim 3 wherein said mechaiiism includes a- hammer biased into yarn holding position and latch means normally restraining movement of said hammer, said means controlled by said pressure responsive element (perating to actuate said mechanism by tripping said latch means. 7. A pneumatic slub catcher comprising in combination an element cut away at one end to form a reentrant chamber, a diaphragm secured to said element and forming a moveable wall of the chamber, said element being provided with 'a restricted inlet passage for air under pressure communicating with said chamber and with aii outlet passage terminating in an orifice on the surface of the element for travel of yarn thereover, a plunger biased into engagement with said diaphragm, a latch controlled by said plunger for release upon a predetermined movement of the plunger, and yarn holding mechanism actuated upon release of said latch. 8. The slub catcher according to claim 7 wherein said element is provided with a second outlet passage terminating in an orifice for travel Of yarn thereover, said passages being closely spaced and terminating in a smooth peripheral arcuate groove in the surface of the element serving gs a guide for yarn in transit through the device. 9. The slub catcher according to claim 7 wherein said element is provided with additional -outlet passages each adapted tb be btought into ,exclusive communication with said chamber, .each of s,,Lid outlet passages terininating in an -orifice on the surface of said elerhent, each of 2,605,635 8 said orifices, when the associated passage is brought into commiinication with said chamber, being in a position for passage of yo@rn thereover. 5 10. A pn.eumatic slub catcher comprising a base, a bracket secured thereto, a pair of annular members mounted on said bracket, a plate secured to said base and having a surface for passage of yarn thereoyer, a hammer slidably lo mounted on said base adjacent said surface, means biasing said hammer toward said surface, releasable means normally holding said hammer in retracted position, a diaphragm secured at its periphery between said annular members, an ele15 ment secured to one of said members and having a chamber formed therein communicating with one wall of said diaphragm, said element being provided with a restricted air inlet passage communicating with said chamber and with an air 20 Outlet passage leading from said chamber and terminating in an orifice on th6 surface of the element for passage of yarn thereover, a frame member secured to the other of said annular members, a plunger slidably mounted in said 26 frame member with one end engaging said diaphragm, a lever pivotally mounted at one end on said frame member and linked to said plunger and means cgrried by the free end, of said lever for releasing said restraining means upon pre3o determined angular movement of said lever. 11. The slub catcher according to claim 10 includin.- a yam tension device mounted on said base in the path of travel of yarn to the surface of said element and a fixed yarn guide mounted 35 on said base in the path of travel of yarn from the surface of said plate. 12. The slub catcher according to claim 10 wherein said element is removably secured to the annular member. 40 13. The slub catcher according to claim 10 wherein said element is provicted with a second outlet passage leading from said chamber and terminating in an orifice adjacent the first mentioned orifice and in the path of travel of yarn. 4- 14. A yarn monitor device comprising in com3 bination, an element having a smoothly rounded surface for passage of yarn thereover, a chamber within said element for fluid under pressure, said element being provided with a restricted inlet passage leading to said chamber and with an outlet passage leading from said chamber and terminating at said surface, mechanism adapted, when actuated, to signify the occurrence of a slub in yarn travelling over said surface and means sensitive to the pressure in said chamber for aetuating said mechanism when the pressure in said chamber exceeds a predetermined value, whereby, when air under pressure is delivered to said chamber and bleeds tQ the atmosphere around 6( yarn travelling at a constant rate over the end of the outlet passage on saidsurface, said mechanism is actuated when a slub of a length greater than a @predetermined length and of a diameter greater than 9, predetermined value travels over the end of the outlet passage. 65 WILMER C. ANDERSON. REFERENCES CITED. The following references are of record in the file of this patent: 70 UNITED STATES PATENTS Number Name Date 21026,155 Abbott ------------- Dec. 31, 1935 2,077,525 Mennesson --------- Apr. 20, 1937 75 2,2b5,399 I-Ianna ------------ Sept. @8 1942 7 1

Patented Aug. 5, 1952 21605 535 STATES PATEN'T OFFICE 1-40NITORING DEVICE Vvi-lmer C. Greenwi@h, Conn.@ as@ ign6r to Deerihg Milliken R6search Triist, Ndtv Ybtk, 16nl3rofit trust of New York Applical@ion January 31,1948, Serial No6 5,58'0 44 ClaIii--ns. (Cl. 28-64) 'Th,e r(@sefit invehtion r6late8 tb the M@,huf'a@c.p titre of yarn a:nd more pa@rticulorly to tl-ib itisteetion of Y-arn for detecti6n iind r6riioval bf oversized sectibbs theteiii, iiiid borApkise8 a nbvel pneifmatieo,lly operated yarn rh6ftitoting device r) which is 8imple and economidol of con@trticti-o'ii, positive in ac@tioii,@ ofid opettlt -es tb tomsb bi7oatoge Of @the e ,yarn when the diamlitot th6rO-of 4@@te @-d@ @t prodetermiiie d Vgluo OV4@it a pred6terhiiht@d length. The iiew device does fi6t dtiiitlgo t'ho Yarn, cbbii 10 be threaded in one siihple Ulie-tOtion bnd is tliiick aetitig, p6rniitting relatiVOI-y- tapid kbte oi yarn travel therethrbugh. The itivontiori includes OIso a novel method of detecting and 8ignalizing yarn dialneter variations 15 There ate various kiAoWn mechanical devices, called @sltib catchers, fiow iii iise in thi@ textile industry, each 6f Which operate8 to cut br break yarn whenever the diameter thereof e-.cceed8 a vglue for which the dovice is 8et. In general, 20 these deivices respond only to the diarhetor of the yarn 'Ond do not distiiigtiish between 8lubs of different lena.th. As very short slubs are ordi@ naril@r not objectionable, niost known devices cut or break the Yarn more often tha;n ig nee6ssarY. q5 This regults in an excess of knots in the Yarii and in u e I:Ibor on the part of the operator whc) niust -remove tho glub from one end of the 'Ydrn after severande by the device and tie th6 Cal slub oatchers now in use, the yarn in its travel i,@- constalitly enggged by tlle otttting or break@ if.ig niember8 of.the dlivice and henc6 its surface l@@to 1-mes abradeci or roughened dilring passage th@ough the device. 35 There ha8 thus been a decided ii(@ed in the industry for a slub catoher thqt ebuld distinguish bL@Ltweon loiig @Ltid short sitibs -and that w.ould not damage the surfaee of the yarn. As slub catchers are used at va-rious stag@s of y -arn 40 mo,nufacturo, a great nttmbet at6 required iii atiy one mill. Hence, it iq of iinportance that the device be of simple and ecbnomical - construction, that it operate witholit f6ilure atid th@Lt it can -be ea8ily. arid:tapidISr roset atid rethreeidi@d. 40@ The morlitor de'vice of the.prosont irivention meets these and other desidereita,. It - discrimiiiates bet@reen short and long slubs, allowing t]@e former to pass and causing bri@okage of the'yarn iipon occurrence of the latter. it is of simple atid .50 durable construction and Liconomical to operote. It has' no-sharp or roiigh Odg6g.fbr travel (if thereov,er and hence does@not damage the arn. y'@ Tn@the neW sliib catcher, ait, or other comptesfl ug@ o@ sible@ uid, is deliveted undot pre@sure't'hro h, 65 severed endstogether. Moreover in the m@chaiii@o f6J@ con@Tenielit mounting bii e@ny suitoble fixed 2 r- t"' t d es rice passage t o a charnber from which it bleed8 to the @Ltino@phere through an brifice oveftliieh tho yarn travels. When the Yarn diam@ eter ext I eed8 a; @predetermined value ovor a preermined length, the resulting increase in pr@s@ @ure in tlj:e chamber operates through a pressureraspoiisive raember to trigger a yarn holding elen I m6 t, the dioLlhLter of slub to be c@iught 'and ininimuin length thereof, depending upon the adjustmtiit .-of, the ttiggering element, upon the su DIS? ptessure, upon the size of 'orifice'and upon @p +.ht 'rate of yarii ttavel. Por g, b-ett6r understanditig of the invention, reference may be had to the accomijanying 'drawinks '01 which: @M9. I i@; a top plan view of a pneumatic y@arn mbiiitor OMbodYing:the iiivention, Pig. 2 is 'a front view of the dovice bf Mg. @l, Pigs. 3 Ond 4 are side view8 of the device Of lqg. i looking from the right and left res,oectiv6ly of Mg. 12, Fig. 5 is a sectional view on the line 5@5 oi Fig. 2, and Mg. 6 is a 'sootioiial@ view of 'an alternative type 6f @res@ure head. Iii thi@ i@ortieWE@k emb6dim, ont of the inven@ tidh@illustrqted iii Figs. 1 to 51 tho vatious parts of tho device are mounted on a b8;se late 2 which p is 8ttuti3d, g@ b)r sdrew bolt8 4 to a brackbt 6 p-att of @i; win ding m4chine br other niechaiiism With thich'thia device is to b6 @ised. Tw6 L8hb,,p6d @iii)pbrt rhoiribe@ts 8 and I 0 are p68itioiiod j:e8pootiv6ly above and below the base '2 with oiio leg of 6ach gecu@ed there@to by bolts 12. The othor leg 8"6f inember 8 supports the pres8ure rb@pbh8iVe @10nierit dnd as8obi8@ted potts of the d6vice toW t6 be describ6d and th6 other leg I O' ofnleinbet'll0support8geonventionaly nguido ar and'tensioiier 14. The DressUre regpotsive elemeilt c@omptises a eirculor diaphr@.igm 10 (see lqg. 5) which is Clahip6d, adjac@nt its periphery, between a disk 18 and ail anliular flange '20 of ii cylindridal M@rnb&t 2.2 as bv means of setews 24. Certairi of ilie-@erews@24 Pas' throu s gh tli6 leg 8' of s-dpport @ 8 @ and: -BOrv6 to4 secure the Osiliiider: 22 td the -SuP@cir.t; @ the ieg 8'. bei'ng cut, away, as shown, fdt receliti6n of the b6d cylinder. 'The Y of the disk@ 18 ha@ @a Peiitt@tl apertute thekdin Whi'c;h is sbrew thteaded 'fo@r @ r@6blitibh of a turned, doivn and e@te@ritliiy throaded pbrtion 26 of the y@ar'n 9,Ltrgtng, head t6 -Head 28-cbiiiprises a g @'t fit@l- @ efle -ali@7 tb.@-6onicAl rAeTAber' having, an exterh@:il a'nh-u-- i 2 s v groovi@ 8' fok iiiding arn in it it66 'bi

3 through the device. Portion 26 and the central part of head 28 are reamed out to provide a pressure chamber 30 communicating with one side of diaphragm 16. An air inlet tube 32 6xtends into a passage 32' in element'28 leading from the face of the element to chamber 30, the tube 32 being press fit and welded or soldered to the wall of the passage or otherwise tightly secured in place so as to prevent leakage of air. The passage 32' and tube 32 are of relatively small cross section so as to offer substantial impedance to the flow of air therethrough. The head 28 is provided with a pair of closely adjacent radial passages 34 of relatively small bore which connect chamber 30 with the annular groove 28' and terminate in orifices 34'. Only one passage 34 appedrs in the sectional view Mg. 5. Cylinder 22, is externally threaded for a portion of its length and i.s provided with a pair of diametrically disposed longitudinal slots 36. An adjusting collar 33 is screw threadedly mounted on the threaded portion of cylinder 22 and a centrally apertured cap 40 is threaded over the end of the cylinder remote from the pressure sensitive diaphragm 16. A rod 42 is axially disposed within the cylinder 22 with one end extending through,the aperture in cap 40 and its other end secured to a disk 44 which fits within the cylinder 22 and engages the diophragm 16. @rhe disk 44 is urged against the diaphragm 16 by a coiled spring 46, one end of which engages the disk 44 and the other 6nd of which engages an annular member 48 within the cylinder. Member 48 has two radial pins 50 secured thereto which extend through the longitudinal slots 36 and engage the collar 38. A lever 2 is pivotally mounted in a yoke 54 rigidly,secured to the cap 40. Lever 52 has an elongated slot 56 therein for reception of the end of rod 42. and has a smaller elongated slot 58 therein intersecting the slot 56 at right angles. A pivot pin 60, extending through the slot 58 and through the rod 42, couples the rod and lever together. The mechanism triggered in response-to a pre determined angular movement of lever.,52 About its pivot resulting from a predetermii-ied increase in pressure in chamber 30 will now be described. A post 62, mounted on the base 2, pivotally supports a bell crank lever 04 cbmprising a long arm 64a and a short bifurcated arm 64b. A rod 66, having a relatively heavy end or head 68, is slidably mounted in a pair of spaced supports 70 which extend up from the base 2 and are rigidly secured -thereto by screws 72. The rod 66 has a collar 74 adjustably secured thereto which is engaged on one side by tho . fureations of arm 64b and on the other side by onb end of a compression spring 761- the other end of the spring engaging the rear support 70. Spring 76 thus tends to move rod 66 forwardly into the position illustrated in dotted lines in Fli@. 1. Lever 52 is provided with a collar 78 which, in the normal position of lever 52, engages a finger 80 on the end of arm 64a and prevents clockwise movement (as viewed in Fig. 1) of th6 bellcrank lever 64 and hetee, through arm 64b, holds rod 66 in the retracted position indicate4d in solid lines in Fig, 1. A ple@te 82'gecured, as by sctews 83,,to-@the bbse 2 serves as a stop for limiting the fofw@:id rhovb,ment of the head 68 of rod.66, the upper paj:t (if the plate being turned outwardly, as indicbted in the drawing, for eiisy insertioii of 3@arn ]5etween the hammer 68 and the stop during the threading operation. -A plate or wall @ section 84 secu@red 2,605,535 4 an eloiigated, partly open sided, slot 84' cut ther6in which serves as a guide for yarn in its exit from the device. The tension device 14 comprises a pair of bell washers 86 which are rotatably mounted on a rod 88 extending through the leg iOl. Ldght pressure between the washers is provided by a compression spring 90 positioned. about the rod 8 8 between the rear surfaeb of the. leg I 0 1 and a 10 collar 92 fixed to the rod. A cap 94 on the forward end of rod 88 completes the assembly of the tension device. Yarn, indicated by the reference numeral 96, travels through the above described slub catcher 15 in the direction indicated by the arrows in Mg. 2. The yarn is supplied from any suitable source and drawn through the device by any suitable take up means; neither the supply nor take up mechanism, being shown in the drawings, as such 20 mechanisms are normal components of mill equipment. Yarn 96 travels between the bell washers 86, makes a quarter turn around the head 28, riding in the groove 28' over the oriflces 341, then passes between the hammer 68 andiplgte 25 82 and out through the slot,841 in guide 84. -As the path of the, yarn includes rio closed gtiide rings or enclosed passages, thre,ading 6f the -device is simple and.rapid, requiiing only a looping of a stretch of the yarn around.the tension de30 vice and head 2 8 and the insertion of the, stretd . h into the open sided slot 84'. During operation of the devieci, -air urider, pressure i8 delivered through the suppl:V'pilie 32 to the chamber 30-, from whenco it bleeds to the at35 mosphere through the passages - 34. The yarn, travelhng in the groove 28', passe@@,6ver the orifices 34' and offers an impedaneb to t.he airflbw which varies with the yarn diameter. , The parts are so adjusted relative. to, the rat;e of travel of 40 the yarn, that when the diametei@ of. the S7arn. 6ver. a predetermined leng,th p-xcee a p@r-edeterrh:ih'6d value, say 200 percent of aVOrage dianietbr the pressure in chamber 30 increase@ toa Valui3 sufficient to trip the hamnier 68 by,ielease of the hold-. 45 ing finger 80; the pressure,in,dhgraber 30 c@ctin through diaphragm I 6 aii@d, rod 42 to @iwing lever 52 outwardly and thereby move.@ collar 78 out of engagement with finger 80. Whon'.finger.80 -is released, spring 76 forces hariimer 68 intb.the 50 dotted line position of Fig. 1 in which position the yarn is firmly gripped b6tWeen the hammer- and plate 82. The continiiing tension of the take ui) mechanism causes the yarn to break whi@n so hi@ld by the device. Upon breakage of yarn the oi3er-. 55 ator removes th6 oversize section bf @a;rn, rbsets. the device by moving arm 64a intb i)6sition where' finger 80 is engag6d by the collar 78, ties the ends of the yarn together and rethreads the device. The above described pneumatid slub catchet ro, 0 may be readily adjusted for detection and el,imination of slubs of different minimum diam6ter and length by adjustment of collar 38 to vary the compression of spring 46. For a. @iveii rate of travel of the yarn, increase in compression bf the 6,5 spring increases the minimum diameter of a g@ven length of yarn or the miniiiium' lbngth.of a g@iveri diameter of yarn necessary f6@ triporg the device. Two closely spe@ced outlet.passage@, @ather th@;n 70 a single outlet @passage havef been shown in the, drawings, a@s I sucli coristruction @@6duces. the tbndency toward turbule nce..e4nd,.henc6 is @r6ferred, In designiilg I the head 28 th6, passage 32' and tubing 32 are made of such @ize that the inito the base 2 at right ahgloi@,tb'the PI @ate 82 lids 75 @6dand.6 @offeted, ther6by 'i@o- the @.iir flo be w

8i!bgi@;titially equal' to that offered by the yailn v@-hie -n -rdi @ avotage dieGmOter so that the ilormal ptcissiire ih'bhamb'cir 30 is substantially half that of the supply pressure. A device constructed in E@ecokd@nce with the above degeribed. embodiment of . th6 in@Tetition @'@Lfid having siibsta;iitially the I)r6p6rtion8 ihdicated t,,i the &e@viings has beei,,l tsed'- satigfactotily to catch slilbs in yarli:having ,q ccitt6n6ount '6f 12!s @and travelling ot @25:feet ]@6r@80dond-. Tli@:8ize of the oriFices 34' of sueh deiv@ic'eN,@a@-.0018quo,reip-th. Witha@supply@prosgiifb 'of% @'teii pound@ @per sqilare inth, -the 'device o!3et6ted 't-0 'catch slubs in -the @akn of over: oneh@tlf iri6h -in. l@@ngth gnd -cif a @diametet of at least twfce the avertlge diameter bf the yarn. @ The oi)tiinuin total cross .8ection of the :ciiitlet lias , sages -3-4' 'depencls upon the @avekoge digmeter of the yarn to be @handled. W-ith the consttucti@on @illugtrqted in Mgs. 1 to @5, the P!7essuke;hea@d 28 niiiy bO readily removed fcir :replb@cement bY a head hogving outlet pas@agi2s@6f differeftt cross ,96-ctioi,i whon yarn of different @-,tverage diaineter is to behandled@ A @cdnstruction of pressure hea@d ,,vhich can be adjusted for use Nvith yarns of dif f6tent aVOrgge diameter is shown iii I-lig. 6. : In Fig. 6 the pressure head 2@Oa is @ made up of three sections 98,'f 00 and!1'02, which are held together byla bolt 104 passin.- axia.Ily tiirough'portions :100 n-nd 102 and getow threaded i-jato the portion @98; a ;lead Nvasher l@06 beiii,- ;pro-vided bet , ween 'the head lt8 of @tho bolt and @'the 6uter Rurface of portion :1@02 to 'insure a' substantially airtight @ fit. An ani'lular flange I Oa of portion 98 is secured, like disk I 8 df @tli:e construction of Figs. 1 to 5, to the parts 2 @3 and .18' of the device by the screws 2 4; 'the.:diE@phtag -m 'I 6 beihggrippedbetween'theparts-18aand:20. Porti6n 98 has @the Dre@sur-e -ch@tmber @30a formed therein and is provided with a passage:l I g,thidh is offsot radially. from the ax-is of the head- and aliiied,with:a similarly radiallj@ offset inlet - ,oassage II 2 in portion 102 of the hoad 2 8a. @ Portion 1,00 @is Ptovided -vvith a @plurality of rodial @outlet passa@ges of differetit dross-se6tion of which' V@ol iiidicated at 114!and 11:6,@o@ppearin,:tho:@ross-seetional@ vi6w @Fig. 6. The pottion IGO @ is provided @vi.th @l numb6r of longitudinal @pas@ages I @i 8 @oqual to;the: iiiimber of oiitlet passages and adapted @to be indivi dually brought into aliiiemA-Tit witl-i the pasga;ges -1 f 0 @aiid I 1 2 @in -portibns '98 and 102 @@te-@ s@@ettiV61y-'-by - rot@tion of the 3)ottion @100 abdut the cominon axis of the'head '2 . Ba; ea;ch longitudinal pa@@sage II 8 'intereeliting one tadial '13a@ssa@ge. 'To @ perrait r6tation 6f the@ cenural portion 1-60 while p@-eventi . ng r6tati6n@ of i)ortion 10.2, a sheb,th l@20 is provided about the bolt 104 and this sh6:iil,i is of rectangillar -cross @ection at each ibnd,thile:6f circular dross gection for the stretch extendin'u@ through the @porti6n [tO; the shegth ng into 66rresponc . fitti iingly shap6d axial h6les in-the,three portions'of the'he@Ld. An@ @uitable means inby be provid6d, for rotat-@ irig,ihb pbrtion ICOto'bring a different @outlbt@ passage I I 8 into alineiyi@-i@i w,ith pa@sages I I 0'aiid I 1 2 when yarn of differerit-',e@verage- diameter- is- to be'ha,ridled.,@ -In the particular construction illustrated in Fio;. @ 6, the. portioii I 00 is provided,on its outer:su.-f ace with radial cavities 12 2 @ f or receptl&n 6f @ui aoie pins or ke@s b-y meaiis of which,. when bolt 1.94 is looseTii,,d, the loortion I 00 may be adj'usted to -a@ ny de@sired position. With this arrangement the smooth contour of the head,28a, niakiif,-@', for@. easy threading of @the device,:-,is not disturbecl. as.shown.-at.-124;@- itable:, is @ prov-ided for @insuring proper -alinement -of -the passages after angular movement of the portion i 00. Any'suitable means, tuch as -the ring seolls indicated d@iagrammatically at@-1,26 inay-be@@pro-@ vided ' for, pre@renting Undue leakage of: air fr-am@ the device. From the' above.,description it @will be apparent that when portion :1 0.0 is in the angular position shown in Mg., 6 and air under pressure is -deliv10 eed to the inlet passage II 2-, outlet passage :1 14 is connected to the inlet passage and to chamber 3 Da and hence the pressure acting on the diaphragm 16 will be responsive to the diar@eter of yarn, 9,6@ passing@over@the terminal orifice@.of passage l@1-4. 1,3 In this position of the p6rtion @100, the longitudival passage:'i 1-8 communicating -with outlet passage If 4 is in :alinement with @passa.-es I IO and If 2 but all of the other longitudinal passages 1 1.8 are blobked . at their ends.by the surfaces of por20 tions 99 and :Iff2. When a yarn of a different average diameter.is to be handled, for example, one.for which the outlet orifice 6f passage 1.1,6 is suitable, it is only necessary to unscrew :bolt 1,04 sufficieiatly to@permit relative.rotation of @por25 tion I 00, ii-isert a @pin or key in.a;cavity 122 and rotate portion @ 1,0 0 @through 180' until the detent 124 slips into the cooperating indentation 124' in the surface of portion IGO. :!In this position of the pqrts, a i)assage I IS Nvill be in communica-, tion with the air inlet passage and with the chamber @30a and the terminal 6rifice of passage I 1'6 will be in the path of travel of the yarn. The radial passa.-es of the portion 100 of @head 23a could be, and prefetably would be, in poirs, like the@passages 3A of Figs. 1 to 5 as such construction reduces any tendency@to turbulence of the emitted air. I The inve-ntion @has @now @been described with reference to one specil-ic embodirnent thereof and -to with reference to a rnodification @of one part. Obvously, various changes could be made in the illustrated coiistructions without depdrting frbm the 8pirit bf the@ iii77ention as d6f!ned in the,appeiided claims. It ivill be appar6nt that the plieu45 rqatic slub catche@ of the invention c6mprises -an efficient devic6 wherein increase in fluid pressure occasibned by: a slub in the yarn is utilized t6' trip a mechanism which catches or holdg the yarn so thilt- the slub may be removed,' the yarn itself 50 forming part of a variable orifice throu@-h which th,,'fliiid@.escapes u-@ider pressure to the atmosphere. As the yarn in its travel through the device engages bnly 'smooth rouiided surfaces,, it is 55 iiot subjected to wear or damage as in mechanical slub catchers heretofore in.use. Moreover, because tripping of the yarn holding nlech anism occurs.brily when the diameter of apr edetermined length of yarn exceeds that desired, @hort unobjectionabit- si@bs or lie s will travel through the 6o p devic6 witliout actuation of the hammer, with corresp6nding conservation of @time and labor @of the attendant. The term "yarn" in the foregoin.- descriptibn and in-the apperided claims is intended to include 65 any te ktile'filamentary Iiiiaterial, thether of one or oi a plur@ality of filaments, whether formed of ptaple @ fibers or of continuous f- !laments and ,vh6ther t,,visted or untwisted. 70 The following is