Brother b831 Service Manual Download Page 1

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Summary of Contents for b831

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Page 2: ...rocking mechanism 16 T Lower shaft thread trimmer and rotary hook mechanism 16 HPresser mechanism 21 T Thread wiper 21 d Reverse switch mechanism 23 d Reverse mechanism 23 d Cover 24 STANDARD ADJUSTMENTS A 25 VB831 8832 8835 8836 B882y d Needle and feed timing B831 25 d Adjustment of needle barto presser bar gap Models 8831 8832 8835 8836 8882 28 d Needle and rotary hook timing adjustment 29 d Rot...

Page 3: ...ns 60 Ul Needle and rotary hook timing adjustment 61 0 Clearance between rotary hook and needle plate 62 0 Clearance between rotary hook and bobbin case opener 62 0 Presser foot height adjustment 63 0 Feed dog height adjustment 64 0 Vibrating presser foot and lifting presser foot and needle timing adjustment 65 0 Upper feed adjustment 65 0 Vibrating presser foot and lifting presser foot vertical s...

Page 4: ...terials For medium thick materials For thick materials Sewing speed 1 4000 spm 3000 spm Stitch length 0 4 mm 0 5 mm Presser foot height Presser foot lifter 7 mm Knee lifter 7 mm Feed dog height 1 mm Needles DP x 5 DPxS l 1 DPx5 l4 DPx5 22 LT2 B882 Sewing speed Stitch length foot height Knee lifter Feed dog height Needles DP x 5 For medium thick materials For thick materials 3000 spm 0 7 mm Special...

Page 5: ... mm DP X 5 For medium thick materials 5 For thick materials 3000 spm 10 5 mm 1 0 mm DPx 5 LS2 B837 Use For thick materials Sewing speed 3000 spm Max stitch length 8 mm Presser foot Presser foot lifter 1 0 5 mm height Knee lifter 1 6 mm Feed dog height 1 0 mm Needle DPx 17 LT2 B838 Use For thick materials Sewing speed 3000 spm Max stitch length 8 mm Presser foot Presser foot lifter 10 5 mm height K...

Page 6: ...Treadle unit ...

Page 7: ...No Part No 12 1 226393 001 12 1 226393 001 Treadle Unit No Part No 5 30 224396 030 5 30 224396 030 Control Box Assembly V Part No 110 220V 100 200 V 226531 002 226426 002 110 220 V 100 200 V 226531 002 226426 002 When ordering a motor be sure to specify the sewing machine model number intended materials to be used and either single or three phase Parts in the above table are for both single and th...

Page 8: ... up lever via thread take up lever slide block which is connected to needle bar crank rod 0 U NEEDLE FEED MECHANISM W o When pulleyO turns in the arrowdirection its rotating motion is conveyed to upper shaft O to turn timing beltwheel upper 0 The motion is conveyed to timing belt wheel lower 0 via timing belt Eccentric wheel O which is connected to lower shaft 0 rotates via timing belt wheel lower...

Page 9: ... B837 sewing machine does not contain a left side rotary hook etc because of the one needle E FEED MECHANISM m When pulley O turns in the arrow direction its rotating motion is conveyed to upper shaft O to turn timing belt wheel upper O The motion is conveyed to timing belt wheel lower O via timing belt O Eccentric wheel O which Is connected to lower shaft O rotates via timing belt wheel lower O a...

Page 10: ...trolled by theshapeofknife driving cam 8 After returning movable knife solenoid O isOFF andknife main lever roller O isreleased from knife driving camrecess ID TENSION RELEASER MECHANISM 2 3 5 6 7 Tension release cam Roller When thread trimming signal comes from synchronizer solenoid O is ON and plunger O is pulled in the arrow direction The motion is conveyed to knife driving pin lever O via knif...

Page 11: ...ssembly changes from forward stitch to backward stitch by the inclination of feed regulator fvlovement is conveyed to switch assembly via switch arm by switch connecting arm a THREAD WIPER Thread wiper L Thread wiper solenoid I o Stopper Thread wiper R After thread trimming with the interval of 10 100 ms thread wiper solenoid O is ON The thread wiper solenoid O drives thread wipers L and R via sol...

Page 12: ...block operation shaft 6 When the convex part of sliding block assembly contacts the clutch lever of needle bar connecting stud attached to needle bars the clutch in needle bar connecting stud breaksawayfrom needle bar and needle bar stops When the left side needle is caused to stop the reverse sequence is performed Cancellation of Needle Bar Termination When push lever is pressed it becomes loosen...

Page 13: ...d to top feed eccentric wheel crank O Bell crank link O causes the up down motion of top feed presser link O via bell crank O The lop feed presser link O S guided by the groove oval of middle presser guide plate E and conveys motion to top feed presser bar O Middle presser affixed to top feed presser bar is caused to move up and down By loosening wing nut and adjusting the position of hinge screw ...

Page 14: ... detector 0 PRESSER MECHANISM Procedures 1 Loosen two screws 0 and remove two needles 0 2 Loosen two screws 0 and remove thread wiper R 0 and thread wiper L 0 3 Remove screw 0 and after raising presser lift lever O remove presser foot 0 4 Remove stud screw 0 and remove knee lifter lever spring 0 and knee lifter lever 0 5 Remove two screws 0 and connecting rod knee liftingjoint ball bearing 0 Remov...

Page 15: ...SHAFT AND THREAD TRIMMER MECHANISM 1 Rotary Hook Procedures 1 Loosen screw O and remove screw 0 then remove throat plate 0 2 Remove flat screw 0 and remove bobbin case opener 0 and washer 0 right and left 3 Turn over the machine 4 Loosen three screws O right and left screws 5 Remove two thread cutter return springs 0 6 Turn the machine upright 7 Remove screws 0 0 and remove movable knife 0 8 Turn ...

Page 16: ...mbly main lever return spring and rubber Remove two flat screws and remove thread trimmer solenoid Remove the pin terminal from the 12 pin plug Lower Shaft Procedures 1 2 3 4 5 6 7 8 9 10 11 Remove timing belt O Remove switch mechanism spring O Remove screw 0 and remove spring peg O Remove flat screw 0 and remove feed bar fork 0 and washer O Loosen screw 0 and remove set screw 0 Loosen two screws ...

Page 17: ...achine upright 7 Remove two flat screws 0 and remove slider assembly 0 right and left 8 Turn the machine over 9 Loosen two screws 0 and screws and and raise feed bar forward 10 Remove rotary hook base L and then rotary hook base R 0 REVERSE MECHANISM 12 pin plug Procedures 1 Turn the machine upright 2 Remove screw O and remove reverse solenoid cover 0 3 Remove stud screw 0 4 Remove three flat scre...

Page 18: ... The thread take up lever slide block disconnects Insert a wedge to needle bar rocking connecting bar 0 and remove needle bar rocking shaft assembly 0 0 REVERSE SWITCH MECHANISM S 12 pin plug o o o o o o o o Terminal pin black Terminal pin white Procedures 1 Loosen flat screw 0 and remove actuator bar 0 2 Remove two flat screws 0 and remove micro switch case 0 and washer 0 3 Remove two screws 0 an...

Page 19: ...0 to thread take up lever sliding block O 4 Install stud O with screw Q Insert stud O by lifting tip of oil reservoir U LOWER SHAFT THREAD TRIMMER AND ROTARY HOOK MECHANISM 1 Lower Shaft Part One m Procedures 1 Turn the machine over 2 Install rotary hook base R O and then rotary hook base L O Install rotating hook bases O and O without the felt protruding 3 Insert feed bar O between rotary hook ba...

Page 20: ...th screw Tighten screw to screw seat 2 Thread Trimmer and Rotary Hook spacer Spacer Spacer Procedures 11 Turn the machine upright Install slider assembly O to rotary hook bases and O with two flat screws O right and left Verify that slider assembly O operates smoothly right and left Turn the machine over Insert lever LO and rocking arm shaft O to rotary hook base and install rocking arm with set s...

Page 21: ...p of needle 0 enters thecenter offeed dog0 needle hole Afterwards fasten screws 0 and 0 in that order Fasten screw 0 when the needle bar rocking crank 0 is at the center of its swing Adjust to 14 2 mm in step 0 above with models B835 and B836 8 Si Rotary Hook Base Position Adjustment ai 0 2 mm 2 mm Procedures Rotary hook point Rotary hook point 2 4 mm 0 05 mm Center of needle 0j np About 0 2 mm Re...

Page 22: ...ssed adjustwith screw 0 so that the roller of knife main lever 0 can easilyenter the recess of knife driving cam 0 Red dot 0 5 mm T mark Thread presser spring Slider n 5 mm Terminal pin black 12 pin plug Terminal pm white Procedures 9 Fit fork lever and screw 0 to the forked part of the plunger Place pin lever and screw 0 and shaft 0 to fork lever 0 Fasten with screw 0 so thatthere is a space of0 ...

Page 23: ...ase opener 0 is 0 2 mm with screw when bobbin case opener 0 is fully pulled back in the arrow direction right and left Procedures 7 Loosen screw 0 remove screw O and remove throat plate 0 8 Turn the machine over 9 Remove knife return spring 0 right and left 10 Turn the machine upright 11 Temporarily fasten movable knife with screw o and screw 12 When bobbin case opener 0 is fullypulled back adjust...

Page 24: ...t O 7 Fasten screw 0 so that there is a space of 1 mm between presser bar bracket O and the metal bushing 8 Install tension release plate 0 and tension release connecting rod 0 with two screws 0 and screw 0 9 Install knee lift lever 0 and knee lift lever spring 0 with stud screw 0 Attach knee lift lever spring 0 to knee lift lever 0 Presser Pressure Adjust by turning presser adjustment screw 0 HI ...

Page 25: ... 2 Install micro switch O with screws O 3 Install actuator bar O with screw 0 4 Install micro switch coyer O with screws O and washers O 5 Install the thread wiper cord and reverse switch cord with two cord braces O and two screws O 6 Install the terminal pin to the 12 pin plug 7 Adjust actuator bar play with stop screw O and then tighten nut 0 22 ...

Page 26: ...everse link O and reverse crank O with screw O 6 Secure the cords with the cord clamp and screws 7 Install reverse solenoid cover with screw 8 Install terminal pin to the 12 pin plug Terminal pm black 12 pin plug o o o o o o o o o o Terminal pin white 8B REVERSE ASSEMBLY ADJUSTMENT 1 Set the feed regulator dial to the maximum setting 2 Loosen screw and raise the reverse solenoid plunger O until it...

Page 27: ...U COVER Procedures 1 Install 2 Install 3 Install 4 Install 5 Install 6 Install 7 Install washer ...

Page 28: ...t the timing belt O on the pulley Right the machine head and install the needles SI Needle and Feed Timing Standard model B832 BB35 B882 Red dot Reference line Remove the needles Tilt the machine head back and remove the timing belt O Turn the machine pulley until the A mark is aligned with the red dot While holding the upper shaft so that itwon t move alignthe arrowon the lowerbeltpulley with the...

Page 29: ...ion of the upper and lower shaft timing T mark from the center of the red dot is 2 mm Upper and Lower Shaft Timing 1 Remove riming belt O 2 Turn the machine pulley until upper and lower shaft timing T mark is in line with the red dot 3 With main lever shaft O depressed turn lower belt wheel O in the arrow direction until it gets hard to turn 4 Keep the machine pulley and lower belt wheel O still a...

Page 30: ...d the pulley and timing belt wheel lower0 in place and mount the timing belt 0 Put the belt around the upper wheel first 5 Push main lever shaft 0 and turn the pulley to a point where it is hard to turn Check that at this point the red dot is in line with the T mark Allowable deviation 2 0 mm Ifdeviation is greater than 2 0 mm remove the timing belt Additional positions are provided at 6 3 and 6 S...

Page 31: ...center of the needle hole 0 in the feed dog 0 Adjust the feed dog 0 if necessary Turnthe feed driving shaft 0 to adjust the feeddog 0 position so the needle enters the center of the needle hole Dimension A Model A B831 B832 B882 1 3 5 mm B835 8836 1 4 2 mm S When dimension A is too large feed dog The feed dog will strike the needle plate when the feed control dial is set to maximum Skipped stitche...

Page 32: ...k is to prevent needle to rotary hook point contact Be sure to readjust the needle guard position when the rotary hook is replaced 2 Needle bar rise and height Needle bar rise specifications vary withdifferent models Use the following table to adjust the rise The gap between reference marks is 2 4 mm Models B831 6832 B835 6836 B882 Model Rise Feed dial Application Standard Thread cutter Standard T...

Page 33: ...nd align the rotary hook point with the needle center When the rotaryhookpointisalignedwith the needle center confirmthat the spacer between the top ofthe needle eye and rotary hook point is 1 1 5 mm 8835 8836 1 When the needle bar o IS in its lowest position theneedle position reference line a of theneedle barisalignedwith the bottom edge of the needle bar bushing O 2 When the needle bar O is2 4 ...

Page 34: ... 2 mm when the bobbin case opener is pulled all the way in the direction ofthe arrow Loosen screwO and move the bobbin case opener O right or left to adjust Needle to rotary hook point gap Improper adjustment may result in improper right and left needle stitching skipped stitches thread breakage broken needles Needle bar rise height Improper adjustment mayresult in improper right and left needle s...

Page 35: ...ight Firmly retighten screw Q after adjustment is completed Be careful not to turn presser bar O Use a presser foot with no front gap to prevent stitch skipping or thread cast off at the start of sewing when working with thin and standard materials Refer to page 67 for presser foot types Subclassification 1 Standard Thread Cutter Mndel Presser foot height B831 B832 B835 B836 B882 B832 400A B835 40...

Page 36: ...eed bar O to adjust the height The back of the feed dog needle hole should be smooth to enable free thread passage Firmly tighen screw O after adjusting the height ffl If the feed dog is too high The feed dog will strike the needle plate Stitches will be longer than indicated bythe feed regulator dial ffl If the feed dog is too low Stitches will be shorter than indicated by the feed regulator dial...

Page 37: ...bar lifter lever O 3 Turn the tension release lever O to adjust the tension disc gap O 2 During thread cutting 1 The tension release crank O to presser bar lifter0 gap should be 1 5 mmwhen the tension release is not operating 2 Loosen nut O remove screw O and adjust with the link 1 5 mm S Insufficient tenison disc gap The thread will be held too tightly and will not pass smoothly through the disc ...

Page 38: ...tor dial O clockwise 3 Tighten screw O 2 Reverse feed sewing Reverse feed stitch length is determined by the fonward feed stitch length 3 Aligning forward reverse feed stitch lengths 1 Adjust the forward feed stitch length 2 Sew Stop the machine with the needle below the top of the needle plate 3 Drop the reverse lever O reverse feed switch all the way down to sew in reverse 4 Adjust the reverse f...

Page 39: ... the reverse lever O Tighten screw O An excessive gap between the solenoid base and reverse feed solenoid plunger will decrease the strength of the magnet and may prevent reverse sewing Reverse switch adjustment 1 Loosen screw O and position the pushbutton O where it is easy to reach 2 Firmly tighten the screw O 3 Loosen nut o and turn screw O to adjust the pushbutton so that the switch is activat...

Page 40: ...s 0 and move the thread wiper Oto the rightor left sothat the thread wiper Owill positivelyhook the threads with its hooked end About 1 mm Solenoid plunger More 0 Less Loosen the screws O and raise or lower the stopper O until the clearance between the tip of thread wiper O and the presser set screw is about 1 mm when the thread wiper returns to its original position If the clearance is too little...

Page 41: ...eat the thread wiper O will strike the presser foot If the gap is too small thread wiping will not be properly performed Bi Step 6 If the 1 mm gap is too great the thread wiper O will strike the presser foot ffl Step 7 above If the 0 5 to 1 mm gap is too great thread wiping will not be properly performed If the gap is too small the thread wiper O will strike the needle tip 38 Needle 0 5 1 mm ...

Page 42: ... If the thread end is not clamped lightly on horizontal rotary hook machines stitch formation at the beginning of sewing is not possible The bobbin thread clamp spring O is provided on this machine to holdthe thread end The bobbin thread clamp spring O should be installed directly below and slightly to the side of the movable knife Note Be careful th clamping area of the bobbin thread clamp spring...

Page 43: ...e cover O Loosen the screw O remove screw O and remove the needle plate Tilt the head back Remove the knife return spring O and return the head to its original position Operate the oscillating arm O until the screws O am visible with movable knife on right Remove the screws O and remove the movable knife O Remove the screws O and remove the fixed knife U ...

Page 44: ...e screws Note the fixed knife has right and wrong sides Fastenthe needle platewith the screws and Fasten the cover with the screws Tilt the head back and install the knife return spring Return the head to its original position Install the needles m the needle clamp and lower the presser foot Oil whetstone gg g jj g jj g gjjge is clean and sharp Cutting part A ragged edge may result m thread breaka...

Page 45: ...main lever roller easily entersthe knife driving arm recess Tighten the nut on the stopper screw O so that the screw will not loosen after the adjustment is completed M KNIFE DRIVING LEVER ADJUSTMENT Knife driving lever 0 5 mm When the mam lever shaft O isat rest the knifedriving lever O to movable knife base bracket O gap should be 0 5 mm Loosen screw O to adjust the knife driving lever O Be sure...

Page 46: ...igned when the treadle is pressed to reverse The needle up stop element should be at approximately 8 on the position detector scale Adjustment Loosen screw O and move the thread cutter element O needle down stop element O and needle up stop element O respectively QZI CORNER SEWING POSITION ADJUSTMENT B835 B836 1 Needle feed rocker crank adjustment Turn the center screw O in the fork of the slide a...

Page 47: ... either independently Itwill be hard to drive both or either needlefs ifthe drive torque is too great 3 Slide shaft adjustment Slide shaft support bracket Set stop lever O to Ron position guide O Loosen screw 0 and move lever shaft arm 0 right or leftso that the end of slide shaft O is even with the end of slide shaft support 0 Lever shaft arm 0 will not function properly and levershaft arm spring...

Page 48: ...needle bar assembly 5 Stop lever aim spring pressure adjustment Spring pressure control collar position at stop lever position R Spring pressure control collar position at stop lever position L Spring pressure is properly adjusted if the stop leverO stops at thecenter dotwhen the push lever O isreleased from the L and R positions ScrewthecollarO tightat the pointwherethestop lever armspring0 light...

Page 49: ...O bottom should beapprox 0 5 mm Turn theneedle barstop O to adjust Presser foot height B835 900 1 The presser foot O should be raised 7 mm above the needle plate by the presser bar lifter cylinder O 2 Loosen screw O and vertically adjustthe cylinder bracket O to adjust Firmly retighten the scew O after the adjustment is completed 46 ...

Page 50: ...g belt on 1 Install timing belt O m the arm opening and place belt O around the timing belt wheel upper 2 Fit the machine pulley onto the upper shaft and fasten it with screws O Align the front screw as viewed in the operating direction of the machine with the arms screw seat 3 Refer to page 50 O needle and feed timing adjustment Mount the sewing machine pulley so there is no horizontal play in th...

Page 51: ...ket O Remove with the thread take up cover in place on the top cover O Remove bed slides L O and R O On B838 remove the set screw and remove bed slide F Loosen set screw and the needle Remove screw and needle plate Remove set screw and the vibrating presser foot Removal will be easier if the vibrating presser foot is first raised with the presser foot lifter lever Loosen set screw and remove the l...

Page 52: ...SSER FOOT AND WALKING BAR 1 PRESSER FOOTO 1 Loosen screw O and remove the knee lifter roller bracket O 2 Remove cotter pin 0 and remove knee lifter complying bar 0 3 Remove stud screw 0 and remove the knee lifter connecting rod 0 4 Remove stud screw 0 and remove knee lifter lever spring 0 and knee lifter lever 0 5 Loosen the pressure regulating thumb screw 0 remove screw 0 and remove the presser b...

Page 53: ...e lifting presser foot adjustment screw walking presser bar presser walking presser spring 0 and walking presser bar 8 Loosen screw 0 9 Remove wing nut 0 lock washer 0 springwasher 0 and hingescrew 0 10 Loosen screw 0 and walking bar eccentric crank 0 1 PRESSER FOOT 0 0 1 Remove the cap O 2 Loosen thescrew 0 ofthepresser barguide bracket 0 thescrew 0 ofthepresser barlifter 0 andthescrewO ofthe pre...

Page 54: ...wo screws O and remove the feed dog O Remove stop screw O and the washer and remove the bobbin case opener O Tilt the machine Loosen the three screws O in the pinion gear O and remove the rotary hook O The pinion gear O and opener link O will also come out Loosen screw and remove the feed bar lifting fork Loosen thefeed driving arm screw needle barvibrating crank screw andsetcollar screw Remove th...

Page 55: ... the machine 2 Assemble the needle bar crank rod O thread take up slide O and thread take up lever 0 3 Pass the thread take up pin O and wick 0 through the thread take up lever 0 and insertthisassembly in the arm Tighten screw 0 so there is no play in the thread take up lever 0 Hold the screw stop of the thread take up pin 0 up while passing the wick through the take up lever 4 Insert the needle b...

Page 56: ...barguide O presser barlifter O spring plate D and presser bar guide bracket O 2 Secure the vibrating presser foot O to the presser bar lifter O with screw O 3 Tighten screw O so thedistance from the bottom ofthepresser guide bushing O tothebottom ofthepresser bar guide O is 1 mm 4 Adjust the vibrating presser foot 0 so the distancefrom the top of the presser barbushing O to the bottom ofthe presse...

Page 57: ...g bar eccentric crank 0 washer 0 lock washer 0 and wing nut 0 Screw the wing nut tight at the center of the walking bar eccentric crank 0 groove Secure the lifting presser foot 0 with screw 0 6B Lifting and Vibrating Presser Foot Vertical Timing Adjustment 1 2 3 4 1 2 Loosen wing nut 0 and retighten at the center of the walking bar eccentriccrank0 Loosen bolt 0 Set the outer presser foot 0 and inn...

Page 58: ...crew O Adjust the needle bar vibration crank O sothe gap between the presser bar O and walking presser bar O S 8 2 mm Adjust the feed driving arm so the needle O enters the middle of the feed dog Firmlytighten screws O and when the adjustment is completed Adjust the feed bar so the feed dog extends 1 mm beyond the needle plate top and then tighten screw 55 ...

Page 59: ...ents alignment using the pinion gear Tighten the set screw0 of the lower shaft gear 0 without changing the screwstop used Needle Bar Height The needle hole edge to rotary hook point gap should be 1 5 mm when the rotary hook point is aligned with the needle center Loosen screw 0 and adjust the vertical needle bar position to adjust Firmly retighten screw 0 after the adjustment is completed The rota...

Page 60: ...g bar 0 onto the knee lifter connecting rod O and secure it with the cotter pin 6 Secure the knee lifter roller bracket to the knee lifter complying bar with set screw Presser Foot Pressure Adjustment Adjust the presser foot pressure with presser foot adjustment screw D 0 TENSION RELEASE LEVER 0 o 1 Tighten set screw O so both ends of the thread take up spring stopper O are level 2 Fit the tension...

Page 61: ... 0 o 1 Secure the top cover gasket O and top cover O with set screw O 2 Secure the face plate O with step screw 0 washer O and thumb screw O 3 Install bed slides L O and R O Install bed slide F 0 on model B838 58 ...

Page 62: ...chine 2 Press the knife mam lever shaft O and turn the pulley in the normal direction until it is hard to turn 3 The timing mark T on the pulley should be aligned with the red dot on the machine head Allowable deviation is 2 mm from the center of the dot Upper and lower shaft timing adjustment 1 Remove the timing belt 0 2 Turn the pulley and align the timing mark T with the red dot 3 Press the kni...

Page 63: ...e in feed dog O The presser bar to walking bar presser bar gap is 8 2 mm If the needle does not fall exactly in the center of the needle hole in feed dog O adjust it in the following manner Remove the rear cover and loosen screw O ylove needle bar support 0 little bylittle untilthe tipofthe needle is in linewiththe center ofthe needle hole infeed dog O After the adjustment tighten screw O securely...

Page 64: ...7 2 8 mm 8838 Needle bar rise 1 Turn the feed adjusting knob to position 0 2 Loosen screws O lorlower shaft spiral gearO andmove lower shaftspiral gearO totheright orleft sothatthe rotary hook pointwill be at the center lineofthe needlewhen the needle rises 2 4 mmwith8837 2 8 mmwithBBSS from its lowest position The rotary hook shaft has a screw seat so the above adjustment cannot be made with the ...

Page 65: ...ase opener O has retracted fully in the arrow direction by loosening screw O and moving bobbin case opener O to the right or left Afterthe adjustment tighten screw O securely 0 2 mm 1 Needle to rotary hook point gap Rough seams skipped stitches thread breakage needle breakage 2 Needle bar rise height Rough seams skipped stitches thread breakage 3 Rotary hook to needle plate gap Too small improper ...

Page 66: ...om is 10 5 mm 2 Insert a 10 5 mm block underneath the vibrating presser foot O 3 Loosen screw O and raise or lower either the vibrating presser foot O or presser bar 0 to adjust Firmlytighten screw O after adjustment is completed The presser bar flat spring will cause the vibrating presser foot to drop when the screw O is loosened Be careful not to turn the presser bar 0 63 ...

Page 67: ...r O so hat feed dog O will rise about 1 0 mm above the needle plate Firmly tighten screw O a ter the adjustment is completed ffi When the feed dog is too high Thefeed dog will strike the needle plate Stitches will be larger than specified by the feed regulator dial ffl When the feed dog is too low Stitches will besmaller than specified by thefeed regulator dial ...

Page 68: ...ser foot O and needle timing byturning byturning upperfeed eccentric wheel O After the adjustment tighten screws O securely 0 UPPER FEED ADJUSTMENT This machine is assembled so that upper feed needle feed matches lower feed The reference line on the needle feed rock crank matches the reference line on the collar Ifthe upper and lower feeds do not match increase or decrease upper feed as follows to...

Page 69: ...ing and lifting presser feet will normally rise the same distance Loosen wing nut O and tighten thewalking bar eccentric crank O at the center ofthe long axis Loosen bolt O Lower both the vibrating O and lifting O presser feet to the needle plate O Turn the main pulley Stop when the thread take up crank O is level as shown in the figure Make sure there is no play in the walking bar shaft O ...

Page 70: ...utter 3 Needle eye 01 5 E Type 8 LT2 8832 Thread cutter 5 8835 Thread cutter 51 Needle eye 02 tr Presser Foot Type A LT2 883I 1 3 5 8832 1 3 5 8835 3 5 Type 8 LT2 B832 Thread cutter 3 8835 Thread cutter 3 Slotless Type 8 LT2 8832 Thread cutter 5 8835 Thread cutter 5 t Slot Type A LT2 8836 B882 p4q Needle Clamp Type A LT2 883 8832 8882 n Type 8 LT2 8835 B836 TypeC LT2 8838 Model Subclass Needle pla...

Page 71: ...01 5 1 17369 001 3 158796 001 116503 001 1 16509 001 116502 001 5 150850 001 1 1 17158 001 1 17134 001 3 158791 001 112603 001 1 12659 001 1 12638 001 5 117133 001 1 117368 001 1 17365 001 3 158792 001 1 12604 001 1 12660 001 1 12642 001 5 1 1 7367 001 3 1 58793 001 1 12605 001 1 12661 001 1 1 2645 001 5 144882 001 3 158798 001 1 16506 101 1 16510 101 1 1 6498 001 5 144881 101 3 1 58809 001 151596...

Page 72: ...01 5 1 17367 001 5 1 6 7 9 mm 3 1 58793 001 1 12605 001 112661 001 1 12645 001 5 144882 001 3 8 9 5 mm 3 158798 001 116506 101 1 16510 101 1 16498 001 5 144881 101 7 16 11 1 mm 3 158809 001 151596 001 151 598 001 151597 001 1 2 12 7 mm 3 158797 001 1 16505 001 1 1651 1 001 1 16499 001 5 8 1 5 9 mm 5 158795 001 116507 001 116512 001 116500 001 1 1 4 31 8 mm 3 1 58799 001 1 16504 001 1 16508 001 116...

Page 73: ... 001 149949 001 149952 001 149954 001 149948 001 149950 001 150526 001 150523 001 150524 001 150534 001 150531 001 150532 001 149966 001 14996 001 149962 001 Bed slide L 3 32 2 4 mm 1 8 3 2 mm 158794 001 5 32 4 0 mm 158796 001 3 16 4 8 mm 1 4 6 4 mm 158791 001 158792 001 148585 001 148528 001 5 1 6 7 9 mm 3 8 9 5 mm 158793 001 158798 001 149697 001 1 2 12 7 mm 158797 001 149685 001 5 8 1 5 9 mm 15...

Page 74: ...55724 001 148700 001 148689 001 5 148701 001 148683 001 3 1 6 4 8 mm 3 150844 001 155851 001 148702 001 148687 001 148585 001 5 148703 001 148691 001 7 32 5 6 mm 3 183180 001 156816 001 156818 001 156819 001 1 4 6 4 mm 3 150830 001 155853 001 148704 001 148693 001 5 148705 001 148695 001 5 1 6 7 9 mm 3 150845 001 155855 001 149692 001 149689 001 149697 001 5 149691 001 149687 001 3 8 9 5 mm 3 1508...

Page 75: ... 4 Welting feet with teeth on presser foot I 3 1 6 4 8 mm 1 4 6 4 mm 5 16 7 9 mm Part No Walking Fool 150962 001 Part No Walking Foot 151520 001 151522 001 151524 001 151526 001 151528 001 151530 001 151532 001 151534 001 Part No Walking Foot 151536 001 151538 001 151540 001 Presser Foot Assembly 183007 001 183181 001 Presser Foot Assembly 183008 001 183014 001 183015 001 V Presser Foot Assembly 1...

Page 76: ...23 001 5 16 7 9 mm 151552 001 183024 001 3 8 9 5 mm 151554 001 183025 001 1 2 12 7 mm 151556 001 183026 001 Size Part No Walking Foot Presser Foot Assembly 3 16 4 8 mm 151558 001 183027 001 1 4 6 4 mm 151560 001 183028 001 5 16 7 9 mm 151562 001 183029 001 Part No Walking Foot Presser Foot Assembly 151564 001 183030 001 Part No Walking Foot Presser Foot Assembly 151566 001 183031 001 Part No Walki...

Page 77: ...05 0 01 153910 0 01 Lifting Presser Foot Assembly 009680 6 12 183096 0 01 183098 0 01 183100 0 01 183102 0 01 183104 0 01 183106 0 01 Needle Clamp Assembly Needle Plate Feed Dog 1 16323 0 01 183095 0 01 153881 0 01 153882 0 01 183097 0 01 153886 0 01 153887 0 01 183099 0 01 153891 0 01 153892 0 01 183101 0 01 153896 0 01 153897 0 01 183103 0 01 153901 0 01 153902 0 01 183105 0 01 153906 0 01 15390...

Page 78: ...plete Recommended standard length is 32 to 35 mm Note When using a thick thread excessive tension may retard the backward motion of the movable knife If the bobbin spins during thread trimming the thread may get tangled inside the bobbin or may slip out between the rotary hook and bobbin possibly causing trouble when restarting the machine A conical spring is placed under the bobbin to prevent bob...

Page 79: ... a bobbin O made of lighi alloyto prevent spinning during thread trimming 2 Insert the bobbin into the bobbin case in the direction opposite to the rotating direction 3 Insert the anti spmning springs under the bobbin ...

Page 80: ...ok lubrication Adjust the lubricating oil supply to the rotary hook Refer to p 7 of the supple mentary instruction manual the rotary hook assembly Improper thread take up Thread take up spring Refer to Thread Tension m the supplementary in struction manual spring tension and stroke stroke and tension Rotary hook point Polish the rotary hook damaged point Damaged needle hole in the feed dog Polish ...

Page 81: ...e Movable knife tip and rotary hook stop gap is too large Set the movable knife tip and rotary hook stop gap to 0 05 0 2 mm Improper tension release adjustment Improper needle and rotary hook timing Movable knife stroke is small insufficient movable knife extension Lower thread loop spread ing does not match the rotary hook With the tension release disengaged adjust the tension release lever and p...

Page 82: ...ead take up spring ten sion IShigh or the stroke is too large Thread take up spring Decrease thread take up spring tension or stroke length Upper thread from the needle hold is short Decrease pre tension strength Needle is too thick Replace with finer needle Presser foot for thick mate rials slotted is being used Replace with slotless presser foot Thread does not come easily off the spool stand Ad...

Page 83: ...r screw Presser foot pressure Feed dog height Needle direction and height Threading Presser fool pressure Remedy Replace faulty needle Install needles in correct direction See the section for upper threading See the section for thread tension See the section for needle and rotary hook timing ad ustment See the section for needle and rotary hook timing adiustment See the section for lower threading...

Page 84: ... up spring ten sion and movement Upper thread tension Lower thread tension Needle direction and height See the section for thread tension See the section for thread tension See the section for thread tension See the section for needle and rotary hook timing adjustment See the section for install ing the needle Replace faulty needle See the section for needle and feed timing adjust ment See the sec...

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Brother b831, Service Manual

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