A180E301P02

INSTRUCTION MANUAL

SINGLE-NEEDLE LOCKSTITCH UPPER AND LOWER FEEDAUTOMATIC UNDERTRIMMERINDUSTRIAL SEWING MACHINE

LY2-3750-B1TMODEL

PRECAUTION BEFORE STARTING OPERATION1 Safety Precautions

1 . Whenturningthepoweron,keepyourhandsandfingersawayfromtheareaaround/undertheneedleandtheareaaroundthepulley.

2 . Thepowermustbeturnedoffwhenthemachineisnotused,orwhentheoperatorleaveshis/herseat.

3 . Thepowermustbeturnedoffbeforetiltingthemachinehead,installingorremovingthe“V”belt,adjustingthemachine,orreplacingparts.

4 . Avoidplacingfingers,hairs,obstacles,etc.nearthepulley,“V”belt,bobbinwinderwheel,ormotorwhenthemachineisinoperation.Injurycouldresult.

5 . Don’tputfingersintothethreadtake-uplevercover,around/undertheneedle,orpulleywhenthemachineisinoperation.

6 . Ifthebeltcover,thefingerguard,and/ortheeyeguardareinstalled,don’toperatethemachinewithoutthesesafetydevices.

2 Precaution before Starting Operation

1 . Ifthemachine’soilpanhasanoilsump,neveroperatethemachinewithoutfillingoilinit.

2 . Ifthemachineislubricatedbyadropoiler,neveroperatethemachinewithoutlubricating.

3 . Whenanewsewingmachineisoperated,verifytherotationaldirectionofthepulleywiththepoweron.

(Thepulleyshouldrotatecounterclockwisewhenviewedfromthepulley.)4 . Verifyvoltageand(singleorthree)phaseindicatedonthenameplateofthemotor.

3 Precaution for Operating Conditions

1 . Avoidusingthemachineatabnormallyhightemperature(35℃orhigher)orlowtemperature(5℃orlower).Otherwise,machinefailuremayresult.

2 . Avoidusingthemachineindustyconditions.3 . Avoidusingthemachineinconditionsfilledwithalotofelectricnoisessuchashigh-frequencywelders.

INTRODUCTION　ThankyouverymuchforpurchasingMitsubishiindustrialsewingmachine.　Pleasereadthisinstructionmanualbeforeoperatingthesewingmachine.Pleasereadalso“SafetyManual”,“InstructionmanualforMitsubishiLimiservoX”andoperatethesewingmachinecorrectlyandsafely.

CONTENTSPREPARATION FOR OPERATION ……………………………………………… 11Adjustmentoftheneedlestoppingposition……………………………………… 1

USAGE PRECAUTION ……………………………………………… 11Installationofthekneelifter ……………………………………………………… 12Lubrication…………………………………………………………………………… 23Lubricationcondition………………………………………………………………… 24Adjustmentoflubricationtotherotatinghook ………………………………… 25Adjustmentoflubricationtotheuppershaft…………………………………… 26Adjustmentoftheoilpump………………………………………………………… 27Periodicalcleaning…………………………………………………………………… 38Precautionforthebuilt-intypedetector ………………………………………… 39Installationofthebeltcover ……………………………………………………… 3:Precautiononoperation …………………………………………………………… 3

HOW TO USE ……………………………………………… 41Installationoftheneedle…………………………………………………………… 42Windingofthebobbinthread……………………………………………………… 43Threadingoftheneedlethread…………………………………………………… 54Adjustmentoffeed(stitch)lengthandbackstitch……………………………… 55Balanceofthreadstension ………………………………………………………… 56Adjustmentoftheneedlethreadtension………………………………………… 67Adjustmentofthebobbinthreadtension………………………………………… 68Adjustmentofthepresserfootpressure………………………………………… 69Adjustmentofthefeeddogheight ……………………………………………… 7:Adjustmentofthefeeddoginclination…………………………………………… 7AAdjustmentofforward/backwardstitchlength………………………………… 7BManualPresserbarlifter…………………………………………………………… 8CAdjustmentofthefeedfootandthepresserfoot ……………………………… 8DAdjustmentofthefeedtiming ……………………………………………………10EAdjustmentofthethreadtrimmerdevice ………………………………………10FTherotatinghook,bobbincase,andbobbin………………………………………13GAdjustmentofthegapbetweenthepulleyandthemachinehead……………13

SPECIFICATIONS ………………………………………………14

1 Installation of the knee lifter1 . Pulloutkneeliftershafts(ontherightandleft)asfaraspossible,andsetthem.

2 . Installthedrivingcrankoneachshaft.3 . Setalinkbetweentherightandleftdrivingcrankstoconnectthem.

4 . Installthekneelifterleverontheleftdrivingcrank.

5 . Theoperatingforcecanbelightenedbyconnectingalinkwiththeinsidescrew Ⓐintheleftdrivingcrankasshowninthedottedlineofthefigure.However,inthiscasetheoperationamountofthekneelifterleverisincreased.

PREPARATION FOR OPERATION

1 Adjustment of the needle stopping position

1 . Adjustment of “UP” positionWhenthepedaliskickeddownbyheel,themachinestopsat“UP”position.Ifmarksdeviatelargerthan3mm,adjustasfollows.( 1 )Disconnecttheplug(12pins)ofcablefromthemachinehead.( 2 )Runthemachineandstopat“UP”position.( 3 )Whileholdingthepulley,insertthe“Adjustingtool”inthehole Ⓐ,thenturnthetool.

2 . Adjustment of “Down” positionWhenthepedalis“Neutral”themachinestopsat“Down”position.Ifmarksdeviatelargethan3mm,adjustasfollows.( 1 )Disconnecttheplug(12pins)ofcablefromthemachinehead.( 2 )Runthemachineandstopat“Down”position.( 3 )Whileholdingthepulley,insertthe“Adjustingtool”inthehole Ⓑ,thenturnthetool.

3 . Confirmthestopoperation,thensettheplug(12pins)comingfromthemachineheadintothereceptacle.

USAGE PRECAUTION

Timing mark

Rotating direction

1st mark “Up” position

“Down” position

White

Black3rd mark

3rd mark

1st mark

Adjusting tool

laterearlierBlack mark

White mark

Timing of the needle

Ⓐ

Ⓑ

Knee lifter shaft

Driving crank

Knee lifter lever

Collar

Hinged screw

Link

screw Ⓐ

— 1 —

2 LubricationFilltheoilreservoirwithoilupto“H”line.Oillevelshouldbeperiodicallychecked.Ifoillevelisfoundbelow“L”linereplenishoilto“H”line.Foroil,use“MC70M”specifiedbyMitsubishi.※Refer MC70M：Specificgravity(15℃ )=0.86(g/cm3) ：Viscosity(40℃ )=10.9(mm2/s)

Knee lifter pin

Drain oil screwⒽ Ⓛ

3 Lubrication conditionCheckthattheoilsplashedtheoilsightwindow.

Oil sight window

4 Adjustment of lubrication to the rotating hook

Adjustthelubricationamountoftherotatinghookbyturningthescrew Ⓐ.

IncreaseDecrease

Screw Ⓐ

5 Adjustment of lubrication to the upper shaft

Removethefaceplate,andadjustthelubricationamountbyturningtheuppershaftlubricationadjustingscrew.

Increase Decrease

Crank

Upper shaft

Maximum Standard Minimum

Adjusting screw Ⓐ

6 Adjustment of the oil pumpThestandardadjustmentisasfollows:Theadjustingplatekeepsthebypassholefullyclosed.Todecreasesplashing,openthebypassholeappropriately.

Adjusting plate

Bypass hole

USAGE PRECAUTION

— 2 —

7 Periodical cleaning1 . Machine

2 . MotorRemovedustfromthemotorfiltereveryoneortwomonths.(Continuedoperationwiththefiltercloggedwithlintordustmayoverheatthemotor.)

3 . Control BoxRemovedustfromtheconnector.(Iftheconnectoriscoveredwithdust,themachinemightmalfunction.)

8 Precaution for the built-in type detector

1 . Sincetheopticaltypedetectingelementisusedinthedetector,preventdustoroilfromstickingtothedetectingplatewhenthesewingmachinepulleyisremovedforadjustment.

Iftheyhavestuck,wipethemoffwithsoftclothcarefullysothatthesurfaceisnotscratched,donotletoilpermeatetheclearanceonthedetectingplate.

2 . Incaseofdisconnectionofthepositiondetectorconnector,runningoffthebeltorcompleteconstraintandoverload,themotorisautomaticallyturnedoffafterpredeterminedtimetopreventburningofthemotor.(However,incaseofhalf-constraintandoverload,thepowermaynotbeturnedoff.)Afterthefailureiseliminated,thenormaloperationisresumedbyturningoffthepoweroncethenturningonagain.

Thesameoperationoccursforthedetectormalfunctionorthelinebreakage.

9 Installation of the belt cover1 . Installthebeltcoveronthemachinesideforsafety.Refertotheprovidedinstructiondocumentcontainedinthesamepackage.

2 . Installthebeltcoveronthemotorsideforsafety.

: Precaution on operation( 1 ) Whenthepoweristurnedonoroff,keepfootawayfromthepedal.

( 2 ) Itshouldbenotedthatthebrakemaynotworkwhenthepowerisinterruptedorpowerfailureoccursduringsewingmachineoperation.

( 3 ) Sincedustinthecontrolboxmightcausemalfunctionorcontroltroubles,besuretokeepthecontrolboxcovercloseduringoperation.

( 4 ) Donotapplyamultimetertothecontrolcircuitforchecking,otherwisevoltageofmultimetermightdamagesemiconductorcomponentsinthecircuit.

USAGE PRECAUTION

HookFeed dog

Hook

Feed bar

Oil pump screen

●Removethethroatplateandcleanthefeeddog.Reassemblyshouldbedonebyscrewinginthescrew2-3rotationsbyhandatfirst,thentighteningthemevenlyusingalong-shaftedscrewdriver.

●Leanthemachineheadandcleanthehookandremoveanydustand/orlintinsidethebobbincase.

●Leanthemachineheadandremoveanydustand/orlintontheoilpumpscreen.

— 3 —

1 Installation of the needleNote: Before installing the needles, be sure to turn off the power.

HOW TO USE

Insert the needle upto the bottom of needle clamp and tighten the screw keeping the long groove side facing to the left.

Insufficient insertion Needle distorted

Gap

Long groove left side Timing mark

for DB×1

Timing mark for DP×17

Needle bar

Note：Ifthreadsnappingoccursduringreversesewingwithpolyesterthreads,itmaybeavoidedbyfittingtheneedlewiththelonggrooveshiftedtothefrontside.Normally,avoidfittingtheneedlewiththegroovefacingbackward.

BothneedlesDP× 17andDB× 1canbeused.Usethetimingmarksasshowninthefigure.

2 Winding of the bobbin threadNote: When bobbin thread is wound, keep the presser foot lifted.

　Adjustment ●Tension of wound thread Slackwindingisrecommendedforpolyesterthreadandnylonthread.

●Conically wound thread Movethethreadguidetowardsmallerdiameterofwoundthreadlayer.

●Amount of wound thread Loosenthewindingamountadjustmentscrewtodecreasethreadwindingamountandtightenthescrewtoincreasethreadwindingamount.

Winding tension adjustment nut

Even winding amount of 80% of full capacity

Winding amount adjustment screw

Thread guide

— 4 —

3 Threading of the needle threadWiththethreadtake-upleverlocatedattheuppermostposition,passtheneedlethreadintheordershowninthefollowingfigure.

4 Adjustment of feed (stitch) length and backstitch

●Adjustmentoffeed(stitch)length…AdjustfeedlengthbyturningthefeedlengthsettingdialwhilepushingPUSHlever.

●Backstitch…Directionofstitchingcanbereversedbydepressingthereversesewingleverorpushingthetouchbackswitch.

●Touchbackswitch…Inthecasethattheswitchisturnedtothearrowdirectionby180°,nobackwardstitchingoccursevenwhentheswitchispushed.

Usethisfunctiontoavoidthemalfunctionsuchasunnecessaryreversestitchinginthecasethatthefabriccomesincontactwiththeswitchduringsewing.

5 Balance of threads tension

HOW TO USE

①

②

③④

⑤

⑥⑦

⑧

⑨⑩⑪

Lead the thread rightward

PUSH lever

Feed length setting dial

Reverse sewing lever

Thread

③

④

⑤

⑥

⑧

Touch back switch

A ○

B ×

C ×

Balanced tension

Tight the needle thread tension or loose the bobbin thread tension

Loose the needle thread tension or tight the bobbin thread tension

— 5 —

6 Adjustment of the needle thread tension

●Theneedlethreadtensionshouldbeadjustedonthebasisofthebobbinthreadtension.

●Adjusttheneedlethreadtensionbyturningthethreadtensionnut.

Theneedlethreadtensioncanbealsoadjustedbychangingintensityandmovablerangeofthethreadtake-upspringincaseofsewingthespecialfabricandthread.

7 Adjustment of the bobbin thread tension

1 . ThebobbinthreadtensioncanbeadjustedbyturningthescrewⒶ.

8 Adjustment of the presser foot pressure

1 . Adjustthepresserfootpressureaccordingtothefabricbyturningthepressureadjustingscrew.

2 . Pressureontheboththepresserfootandthefeedfootcanbeadjusted.(Theadjustingscrewpositionisfactory-adjustedasshowninthefigure.)

3 . Sewingpressureshouldbeadjustedtotheminimumrequiredstrength.

HOW TO USE

Tighten

Loosen

Thread tension nut

Screw Ⓐ

Thread tension spring

LoosenTighten

StrengthenWeaken

Standard 30 mm

〈Presser foot pressure〉

Standard 20 mm

Weaken Strengthen

〈Feed foot pressure〉

— 6 —

9 Adjustment of the feed dog height

1 . Turnthepulleyandstopitatthepositionwherethefeedliftingrockshaftcrankswingstotheinnermostposition.

2 . LoosenthescrewⒶ. Note:Becarefulnottomovethefeedliftingrockshaftcrankinthelateraldirection.

3 . Adjustthefeeddogheightbyswingingthefeedliftingrockshaftforkandmovingthefeedbar.

4 . Afteradjusting,fullytightenthescrewⒶ.

The feed dog height is factory-adjusted to 1.0 mm.

Throat plateFeed lifting rock shaft fork

1.0 mm

Feed bar

Feed dog

Feed lifting rock shaft crank Screw Ⓐ

: Adjustment of the feed dog inclination

Thefeeddoghasbeensettostandard(horizontally).Ifnecessary,adjusttheinclinationaccordingtothematerialtobesewnasfollows.1 . SlightlyloosenscrewⒶ.2 . Whilepressingthegroovelocatedintheeccentricpinbyusingascrewdriver,turntheeccentricpinclockwise(tolowerthefrontend)orcounterclockwise(toliftthefrontend).

3 . Afteradjusting,tightenthescrewⒶ.

MarkEccentric pin

Screwdriver

Screw Ⓐ

A Adjustment of forward/backward stitch length

1 . LoosenfoursetscrewsⒶ.2 . Turnthestitchlengthadjustingpinuntilthedesiredlengthisreachedasfollows:( 1 ) Clockwise:Increasesthestitchlengthin

forwardsewing,anddecreasesthestitchlengthinbacksewing.

( 2 ) Counterclockwise:Decreasesthestitchlengthinforwardsewing,andincreasesthestitchlengthinbacksewing.

HOW TO USE

Set screw Ⓐ Bracket Stitch length adjusting pin

Positionofmarkontheeccentricpin Feeddog

Horizontal Standard

Rightabove Frontup(MAX.)

Rightbelow Frontdown(MAX.)

— 7 —

B Manual Presser bar lifter1 . Turnthepresserbarlifterinthedirectionofthearrow.Thisraisesthepresserfoot.

C Adjustment of the feed foot and the presser foot

1 . Adjustment of alternating movement( 1 ) Thealternatingmovementonthefeedfoot

andthepresserfootcanbeadjustedbyusingtheadjustingdiallocatedonthetopcover.

( 2 ) Facethedesirednumberprintedonthedialtothematchingmarklocatedonthetopcover.

( 3 ) Thenumberprintedonthedialrepresentsthepossibleprotrusionofthefeedfootandpresserfootfromthethroatplatewhenthealternatingmovementsontheseareevenlyset.

( 4 ) Ifthealternatingmovementsareevenlyset,theycanbereadjustedupto2.0to5.0mm.

2 . To change the balance of the alternating movements between the feed foot and presser foot( 1 ) Forexample,toincreasetheriseofthefeed

foot,anddecreasetheriseofthepresserfoot.①Removetherubberpluglocatedonthetopcover.②Turnthepulleyuntilthepresserfootisslightlyraisedfromthethroatplate.③LoosenthesetscrewⒶ(ontherightside)locatedonthefeedliftingrockshaftcrank(right).④Thebuilt-inspringpullsdownthepresserfootuntilitmakescontactwiththethroatplate.Then,tightenthesetscrewⒶ.⑤Thiscompletestheadjustment,i.e.,theprotrusionofthepresserfoothasbeendecreasedbyasetdistance.And,theverticalmotionofthefeedfoothasbeenincreasedbythatsamedistance.

( 2 ) Asacontrarycase(1),todecreasetheriseofthefeedfoot,andincreasetheriseofthepresserfoot.

First,turnthepulleyuntilthefeedfootisslightlyraisedfromthethroatplate.Next,loosenthescrewⒶ.Finally,tightenthescrewⒶagain.

Thisdecreasestheriseofthefeedfoot.

HOW TO USE

Presser bar lifter

Alternating movement adjusting dialMatching mark

Presser foot

Feed foot

2.0 to 5.0 mm

Rubber plug

Set Screw Ⓐ

Feed lifting rock shaft crank (right)

— 8 —

3 . Installing the feed regulator bracketShoulditbenecessarytodismountandthefeedregulatorbracketanditsrelatedparts,usetheprocedureexplainedbelow.Note:Ifthefeedregulatorbracketispoorlypositioned,theresultantalternatingmovementsmaybetooshortorlong,causingdefectivemachineoperation.( 1 ) SettheclearancebetweenspecialscrewⒶlocatedontheregulatorstudandthesidewallofthemachinearmto26.5mmasillustratedtotheleft.(Usea26.5mmspacerbetweentheseparts.Thisfacilitatestheoperation.)

( 2 ) Withthefeedregulatorstudheldasexplainedinstep( 1 )above,adjustthefeedregulatorbracket.Thisadjustmentshouldinsureaclearanceof12mmbetweentheperipheryofpinⒷlocatedonthefeedregulatorbracketandthetopcovermountingfacelocatedonthearm.TightenscrewsⒸ.

4 . Feed pitch adjustment of feed footTheratiooftheupperfeedamount(ofthefeedfoot)tothelowerfeedamount(ofthefeeddog)hasbeenadjustedto1:1.However,thefeedfootfeedingamountcanbeincreasedordecreaseddependingontheoperatingconditions.( 1 ) Loosenthenutlocatedontheupperfeed

rockshaftcrank(left),andshifttoadjustthepositionofthesquareblockupwardordownward.

Upperposition:Feedpitch→Small Lowerposition:Feedpitch→Large

HOW TO USE

Ⓑ

Ⓒ ⒶFeed regulator bracket

Feed regulator stud

26.5 mm

12 mm

Nut

Upper feed rock shaft crank (left)

— 9 —

D Adjustment of the feed timing1 . Thestandardpositionoftheeccentricfeedcamandeccentricfeedliftingcamareillustratedtotheright.

2 . Toadjusttheposition,firstopenthetopcover.Properlyslidetheeccentriccam.

3 . Theeccentricfeedcamcanalsobeadjustedbyremovingtherubberpluglocatedonthetopcover,andtheuppereccentricfeedliftingcamcanalsobeadjustedbyremovingtherubberpluglocatedonthearm.

Inthelattercase,however,thebuilt-inbevelgearisconcealed;careshouldbetakenwhenadjusting.

E Adjustment of the thread trimmer device

1 . Configuration of the thread trimmer devise

2 . Precautions for adjustmentTheLY2-3750usesathreadtrimmerdrivesystemwithalowershaftcam.Soifyouturnthemachinebyonerevolutionwiththethreadtrimmersolenoidactivated(i.e.,withtherollerlocatedonthecamfollowercrank( 2 )keptengagedwiththethreadtrimmercam),themovableknife(left)willmakecontactwiththeneedle,breakingthecontactingparts.Activatethebuilt-insolenoidonlywhenthenormalthreadtrimmingcycleisactive(lowerposition→upperposition).

HOW TO USE

Bevel gear for upper shaft

1st screw 1st screw

Rubber plug

Rubber plug

Top cover

Upper shaft 2nd screw

Upper eccentric feed lifting cam

Eccentric feed cam

Fixed knife bracket unit

Thread guideFixed knife

Movable knife (left)

Knife driving crank

Knife driving shaft

Cam follower crank (1)

Cam follower crank (2)

Drive lever Stopper plateStopper

Spring

Spring

Coil spring

Collar

Thread trimmer cam

Flexible wire

Knife base unit

Thread trimmer solenoid unitThread trimmer solenoid

— 10 —

3 . Relationship between the fixed knife and the movable knife (left) edge

( 1 ) Thestandardpositionisillustratedtotheright.

( 2 ) Ifthedistance(0.3mm)istoowide,suchasituationmayallowfor“triple”threadbreakagetooccur,resultingindetachedneedlethreadafterthreadsarecut.Also,ifitistoonarrow,suchasituationmayleadtounexpectedlyuncutthreads.Pleasekeepthisinmind.

( 3 ) Theadjustmentnecessaryinstep( 2 )canbedonebycorrectlyinstallingthefixedknifebracketunitorcorrectlymountingthefixedknife.

( 4 ) ThefixedknifebracketunithasbeeninstalledusingscrewⒶwiththebobbincaseholderpositionbracketremoved(SeeFig.totheright).

4 . Knife driving shaft( 1 ) Thestandardpositionisillustratedtotheright.( 2 ) Whenassembling,theknifedrivingshaftmust

firstbeputthroughtheknifedrivingcrank.( 3 ) Thecamfollowercrank( 1 )mustbepositionedasillustratedtotheright,andsettotheflatontheknifedrivingshaft.

( 4 ) Thestoppermustbesettotheflatontheknifedrivingshaftinsuchawaythattheknifedrivingshaftissnugandsmoothlyturnsintheshaftdirection.

5 . Installing the thread trimmer solenoid unit( 1 ) Operationstrokeofthethreadtrimmersolenoid

①Standardoperationstrokeis6mm.②ThisstrokecanbeadjustedbyusingnutⒶ.( 2 ) Installingtheunit①TheunitcanbemountedbyusingscrewsⒷ and Ⓒ.②Clearanceof1mmmustbeinsuredbetweenthedrivingleverandcamfollowercrank( 2 )withstoppernutⒶmadecontactwiththesolenoid.③Insuchasituation,activatingthesolenoidshouldcreateaclearanceof0.5mmbetweencamfollowercrank( 1 )and ( 2 ).Thissituationisstandard.Tomeetthisstandard,slidethesolenoidmountingbracketinthedirectionofthearrowasillustrated,ifadjustmentisneeded.

HOW TO USE

Screw Ⓐ

Fixed knife bracket unit

Driving lever

Cam follower crank (2)

Cam follower crank (2)

Cam follower crank (1)

Solenoid mounting bracket

6 mm

1 mm

Ⓒ

Ⓐ Ⓑ

0.5 mm

Coil springCam follower crank (1)

Cam follower crank (2)

StopperBushing87.5 mm

Knife driving shaft

Movable knife (left)0.3 mm

Fixed knife

(Knife edge)

— 11 —

6 . Installing the thread trimmer cam( 1 ) Facethe2ndtimingmarkⒶ(Green)locatedonthepulleytothematchingmarkonthearm.

( 2 ) Withthethreadtrimmersolenoidactivated,turnthethreadtrimmercamforwarduntilthecammakescontactwiththeroller.Then,setthecam.

( 3 ) Withthethreadtrimmersolenoiddeactivated,allowthecamfollowercrank( 2 )toreturntoitsoriginalposition.Thisshouldcreateaclearanceof0.5to1.0mmbetweenthecamandrollerend.Thisdistanceisstandard.

7 . Adjustment of knives engagement( 1 ) Positionofmovableknife(left)andfixedknife①Seetheillustration.Thestandarddistancesfromtheneedlecenterare7.5mmand5mmfromthemovableknife(left)andfixedkniferespectively.

( 2 ) Adjustmentofknivesengagingamount①Withthesolenoidactivated,turnonthemachine.Thisturnsthethreadtrimmercamwhichturnsthemovableknife(left).Whenthemovableknife(left)hasmovedtoitsfarthestdistance,thestandardengagingamountofknivesis1.5to2.0mm.

②Theengagingamountcanbeadjustedbyproperlymountingthedrivingcrank.

( 3 ) Adjustmentofknivesengagingpressure①Seetheillustration.Insuchasituation,themovableknife(left)andthefixedknifeshouldfirstmakecontactwitheachother.Thissituationisstandard.

②Ifathreadispoorlycut,particularlywhenitisthick,slightlyincreasetheengagingpressure.Thisshouldsolvetheproblem.

③Theengagingpressurecanbeadjustedinthisway:LoosenlocknutⒷ(SeeFig.),andadjustitbyusingadjustingscrewⒶ.

HOW TO USE

Cam follower crank (2)Knife driving shaft

Matching mark

0.5 to 1.0 mm

0.6 mm

1mm

Ⓐ

Thread trimmer camThread trimmer cam

Roller

Roller

Lower shaft

Knife driving crank

1.5 to 2.0 mm

3 mm

7.5 mm 5 mm

Fixed knife

Movable knife (left)

Movable knife (left)

Ⓑ ⒶFixed knife

Movable knife (left)

Fixed knife

Note: Thestandardpositionofcamfollowercrank(2)beforeactivationisillustratedtotheright.Ifthispositionhasbeenchangedduetoremovalofstopperplate,etc.,firstperformthespecifiedadjustmentbyusingtheadjustingboltlocatedonthestopperplatebeforeadjustingasabovesteps(1)to(3).

— 12 —

8 . Adjustment of the needle thread tension release( 1 ) Withthethreadtrimmersolenoidactivated,adjustmentshouldbesuchthatthethreadtensiondiscslocatedontheneedlethreadtensionregulatorareseparatedfromeachotherbyabout1mm.

( 2 ) Adjustmentcanbedoneinthisway:LoosennutⒶandproperlymovetheflexiblewire.

( 3 ) Movetheflexiblewiretotherighttoincreasetheopeningamount.

9 . Adjustment of the needle thread remaining length

( 1 ) ThelengthofremainingthreadcanbeadjustedbyturningtensionregulatingnutⒶasfollows:　　　Clockwise → Shortinlength　　　Counterclockwise → Longinlength

F The rotating hook, bobbin case, and bobbin

1 . UseaspecialbobbinformachineswiththreadtrimmerswhoserotatinghookhasbobbinthreadguideslitⒶ.

2 . Also,useabobbincasewhosebottomhasspringⒷacapableofpreventingracing.

3 . Thebobbinprovidedinthepackagecanbeused.

G Adjustment of the gap between the pulley and the machine head

Thedetector’sreflectionplateisinstalledontheinnersideofthepulley.Soacorrectdistancemustbekeptwiththedetectorbody.Thegapbetweenthepulleyandthemachineheadmustbe6.5mm.

HOW TO USE

1 mm

Ⓐ

Thread trimmer solenoid

Increase the opening amount

Flexible wire

Ⓐ

Ⓐ

Ⓑ

Rotating hook

Bobbin case

Detector body

6.5 mmAdjusting tool (Enclosed in the accessary box)

Pulley

Note:Ifthethreadtensiondiscsaretoonarrowly,theneedlethreadmaybeliabletobebroken,resultingindetachedneedlethread.Also,ifthespacebetweenthediscsistoowide,theexcessiveblankspacebetweenthediscsmayresultinloosestitches.

— 13 —

LY2-3750-B1T Specifications

ModelSpecifications

LY2-3750-B1T

Application Heavymaterial

Max.sewingspeed(rpm) 2,000

Stitchlength(mm) 0to8

Needlebarstroke(mm) 38.0

Threadtake-upleverstroke(mm) 73.0

Alternatingmovement(mm) 2.0to5.0(feedfoot)

Alternatingmovementchangingsystem Dial(One-touch)

Feeddogheight(mm) 1.0

Presserfootstroke(mm)Hand 6.0

Knee 16.0

Needle DP × 17#22(DB× 1#22)

Hook(verticalrotatinghook) Large

Bobbincase Withracingpreventionspring

Bobbin Madeofsteelforthreadtrimmer

Lubricationsystem Automaticlubrication

ThreadtrimmerRotarytrimmingbyleftmovableknife

andrightfixedknife

Touchback ○

Beddimensions(mm) 517 × 178

Note:●Thebobbinshouldbeofhighqualityfreefromdeformation. ●Somematerialsand/orsewingconditionsmayrequirespecificationsotherthanthoselisted

above. ●Thesespecificationsaresubjecttochangeformachineimprovement.

SPECIFICATIONS

— 14 —

Printed in Japan