Brother B831 User manual

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CONTENTS

[Model

B831

6832 8835 6836 8882]

(

NAMES

MAIN

PARTS

) i

(specifications) 3

(

MECHANISM

) 6

Upper shaft and needle bar mechanism 5

(UNeedle feed mechanism 5

Lower

shaft and rotary hook mechanism 6

[UFeed mechanism 6

d] Thread trimmer mechanism 7

d] Tension releaser mechanism 7

Reverse mechanism 8

d] Thread wiper 8

[9]

Needle

bar

(left

and

right)

mechanism

types

B835

and

B836

(13

Top feed mechanism types 8837 and B838 10

rDISASSEMBLY

PROCEDURES

\B831.

B832, B835, B836. B882y

d] Cover 11

(UPresser mechanism 11

|T|Thread wiper 12

Rotary hook, lower shaft and

thread

trimmer

mechanism

d] Reverse mechanism 14

d] Needlebar

rocking

shaft mechanism 15

d] Reverseswitch mechanism 15

(assembly procedures)

[T|Needle bar rocking mechanism 16

[T]

Lower shaft, thread trimmer

and

rotary

hook

mechanism

(HPresser mechanism 21

(T|Thread wiper 21

d] Reverse switch mechanism 23

Reverse mechanism 23

Cover 24

/STANDARD

ADJUSTMENTS

A 25

VB831,

8832,

8835,

8836,

B882y

d] Needle and feed

timing

(B831) 25

Adjustment

needle

barto presser bargap

(Models

8831,

8832,

8835,

8836.

8882)

d] Needleand rotary hook

timing

adjustment 29

Rotary

hookto needle plate gap 31

Rotary

hookto

bobbin

case opener gap 31

d] Presser foot height adjustment 32

d] Feed dog height adjustment 33

d] Tension release adjustment 34

d] Stitch length adjustment 35

(13

Reverse

feed solenoid adjustment 36

[n]Thread wiper adjustment 37

iniSlider adjustment 39

[13

Movable and

fixed

knife

adjustment 40

03 Knife mam lever roller 42

Knife

driving

lever

adjustment 42

(13

Positiondetector adjustment 43

03Corner sewing position adjustment

(8835,

8836)

03Timing belt replacement 47

CONTENTS

[Model

B837

B838]

CDISASSEMBLY

PROCEDURES\

VB837,

B838

(T)

Cover

(H Tension

release

lever

Uj Presser foot and walking bar 49

G] Needle bar and needle thread take-up 51

UlFeed

assembly 51

(

ASSEMBLY

PROCEDURES

)

Feed assembly 52

[O Needle bar 52

(HWalking bar and presser foot 53

[T)

Tension release lever 57

[O Cover 58

/STANDARD

ADJUSTMENT^

\^B837,

B838

Q]Needle

and

feed timing adjustment (standard)

UlFeed dog adjustment in back and forth

directions

UlNeedle and rotary hook timing adjustment 61

0Clearance between rotary hook

and

needle

plate

0Clearance between rotary hook and

bobbin

case

opener

0 Presser foot height adjustment 63

0 Feed dog height adjustment 64

0Vibrating presser foot and

lifting

presser foot

and

needle

timing

adjustment

0 Upper feed adjustment 65

Vibrating

presser foot and

lifting

presser foot

vertical

stroke

adjustment

"GAUGE

PARTS

LIST

FOR

DOUBLE

NEEDLE

LOCK

STITCH

sSEWING

MACHINES

(

others)

(XlTop

cover thread guide 75

UlAdjusting upper thread length 75

UlAnti-spinning spring 76

[H Bobbin 76

G]To thread bobbin

cases

(8835.

8836)

(troubleshooting guide)

NAMES

MAIN

PARTS

Model

LT2-B831

<Model

LT2-B832>

<Model

LT2.B882>

LT2-B831

Sewing

speed

Stitch

length

Pfesser

foot

height

Feed

dog

height

Needles

LT2-B832

Forlhm

Forlhick

malenals

materials

4000

spm

3000

spm

0~4

0~5

Use

For

thin

materials

For

medium-

thick

materials

For

thick

materials

Sewing

speed

4000

spm

3000

spm

Stitch

length

0~5

Presser

foot

height

Presser

foot

lifter

Knee

lifter

Feed

dog

height

Needles

x 5

DPxS^'l

1DPx5''l4 DPx5^22

LT2-B882

Sewing

speed

Stitch

length

foot

height Knee lifter

Feed

dog

height

Needles

x 5

For

medium-thick

materials

For

thick

materials

3000

spm

0~7

(Special

order

8mm)

2.7

1.0

DPx5" 14 DPx5"22

4^:!:

LT2-B835

Sewing

speed

Sliich

length

Presser

fool

height

Feed

dog

height

Needles

LT2-B836

Sewing

speed

Stitch

length

Presser

foot

Presser

||„er

fool

height Knee lifter

Feed

dog

height

Needles

For

medium-lhick

materials

For

thick

materials

3000

spm

1.0

X 5

For

medium-thick

materials

For

thick

materials

3000

spm

10.5

1.0

DPx

LS2-B837

Use

For

thick

materials

Sewing

speed

3000

spm

Max.

stitch

length

Presser

foot

Presser

foot

lifter 1

0.5

height

Knee

lifter 1 6

Feed

dog

height

1.0

Needle

DPx

LT2-B838

Use

For

thick

materials

Sewing

speed

3000

spm

Max.

stitch

length

Presser

foot

Presser

foot

lifter

10.5

height

Knee

lifter

1 6

Feed

dog

height

1.0

Needle

Treadle

unit

Motor

pulley

Medium

LT2-B832-403A

703A

LT2-B835-403A

703A

Machine

speed

4000

spm

3000

spm

Motor

Pulley

Size

Part

No.

Pulley

224545-000

105

Pulley

226389-000

105

Pulley

226389-000

Pulley

224506-001

Belt

Cover

No.

Part

No.

#12-2

224547-001

#12-1

226393-001

#12-1

226393-001

Treadle

Unit

No.

Part

No.

#5-38

224396-038

#5-30

224396-030

Control

Box

Assembly

Part

No.

110/220

100/200

226531-001

226426-001

110/220V

100/200V

226531-002 226426-002

Thick

LT2-B832-405A

705A

LT2-B835-405A

705A

LS2-B837-300A

Machine

speed

3000

spm

3000

spm

Motor

Pulley

Size

Part

No.

105

Pulley

226389-000

Pulley

224506-001

105

Pulley

226389-000

Pulley

224506-001

Belt

Cover

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

Part

No.

110/220V

100/200

226531-002

226426-002

110/220

V .

100/200

226531-002

226426-002

When

ordering amotor be

sure

to specify the

sewing

machine

model

number,

intended

materials to be used, and either

single

three

phase.

*Parts in

the

above

table

are

for

both

single

and

three

phase

machines.

*Machines and motors for voltages

other

than

those

specified above

can

be manufactured to order. Consult your local

dealer.

* Be

sure

refer

the

parts

book

when

ordering

any

parts.

(2)

Motor

pulley

change

(fr.

-4-

Use

the

V-belt

included

together

with

the

machine

head.

After

installing

the

belt,

loosen

both

hexagon

nuts

and adjust the tension of the belt. Make

sure

that

the

correct

belt

tension

maintained.

Then

tighten

the

hexagon

nuts.

The

belt

can

depressed

about

mm with afinger.

When

pulley

O turns inthearrowdirection, itsrotating

motion

conveyed

touppershaftO toturncounterweightO-

The

motion

conveyed

to needlebarcrankrod

0via

needlebarcrankO

which

isconnectedtocounterweight©.The

shape of arc motion is conveyed to the thread hole in thread take-up lever

©via

thread take-up lever slide block O

which

connected

to needle bar crank rod

Needle bar O moves up and down via needle bar clamp 0 which is connected to needle bar crank rod

Needle bar O is guided by needle bar

support

(The arc motion is conveyed to the thread hole in thread take-up lever © via thread take-up leverslide block

©which

connected

needle

bar

crank

rod

0).

U] NEEDLE FEED

MECHANISM

When pulleyO turns inthe arrowdirection, its rotating motionis conveyedto upper shaft O to turn timing beltwheel

upper

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 0 and lower shaft

©.

Level

via

eccentric wheel

level

feed connecting rod O and

level

feed

connecting link 0

The motion is conveyed to needle bar rock

crank

® via feed rock shaft o

©.

Needle

bar ©

which

connected

needle

bar

support

moves

back

and

forth.

[U LOWER

SHAFT

AND

ROTARY HOOK

MECHANISM

1. When

puiley

O turns inthe arrowdirection, its

rotating

motion

conveyed

to uppershaft O to turn

timing

beltwheel

upper

2. The motion is conveyed to timing belt wheel lower 0 via timing belt

lowershaft O which is connected to timing belt wheel lower O rotates, spiral gear O is turned.

4. Rotary hook rotates via pinion gear O which is connected to rotary hook base

O-

(Opener)

1. Opener crank 0 moves in the

shape

of an arc via rotary hook 0 and

opener

link

©.

2. Opener 0 which is connected to opener crank 0 moves in the shape of an arc.

• The

LS2-B837

sewing

machine

does

not

contain

a left

side

rotary

hook. etc.

because

the

one

needle.

E FEED

MECHANISM

When

pulley O turns in the arrow direction, its rotating motion is conveyed to upper shaft O to turn timing belt wheel

upper

The motion is conveyed to timing belt wheel lower O via timing belt

Eccentric wheel O which Is

connected

to lower shaft Orotates via timing belt wheel lower O

and

lower shaft

Level feed arm 0 moves in the

shape

of an arc via eccentric wheel

level feed connecting rod 0

and

levelfeed

connecting

link

Feed bar 0 moves

back

and

forth via feed rock

shaft

Feed bar fork 0 moves up and down by vertical feed eccentric wheel 0 which is

connected

to lower shaft

©.

The

movement

of feed

dog

is fixed by

the

combination

movements

in item 5

and

item

THREAD TRIMMER MECHANISM

When thread trimming signal comes from synchronizer, solenoid O is

and plunger O is pulled in the arrow

direction.

The motion is conveyed to knife driving pin lever O via knifedriving lever O-

knife

main

lever

shaftO ispushedinthe

arrow

direction,

knife

main

lever

roller

O enters

knife

driving

camrecessO

which is

connected

to lower shaft

O-

According to the recess

shape

of knifedriving cam

the motion is conveyed to knifelockarm 0 via knifemain lever

knife

sub lever

knife

lengthadjustingIink0.

knife

lockleverright®and

knife

The

motion

isconveyed to

knife

lock

arm 0 via

knife

link

0 which isconnected to

knife

lock

lever

right®,

knife

lock

lever left 0 and knife lock arm shaft 0 (left slider side).

Movable knife 0 which is

connected

to slider 0 is moved in

the

arrow

direction.

The

movable

knife

0returns

while

the

roller

knife

main

lever

O is

being

controlled

theshapeof

knife

driving

cam

After

returning

movable

knife

solenoid O is

OFF,

and

knife

main

lever

roller

O isreleased

from

knife

driving

camrecess

ID TENSION RELEASER MECHANISM

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 knife driving lever

As knife main lever

shaft

0 is

pushed

the

arrow

direction,

tension

release

lock lever O is

connected

with

tension

release cam portion of knife driving cam

Rollerof tension release lock lever O is pushed in the arrow direction bytension release cam portion of knifedriving

cam

The motion is conveyed to tension release crank 0 via tension release connecting rod lower

tension release crank

lower

tension release crank upper 0 tension release connecting rod upper 0 and tension release plate

As tension release crank 0

pushes

presser bar lifter

®.

tension disc 0 is moved via tension release bar

tension

release plate 0 and pin.

When

solenoid O is OFF, tension disc is returned to its original position.

-7-

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