Brother b831 User manual

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CONTENTS [Model B831 6832 8835 6836 8882]
( NAMES OF MAIN PARTS ) i
(specifications) 3
( MECHANISM ) 6
CD Upper shaft and needle bar mechanism 5
(UNeedle feed mechanism 5
d]
Lower shaft and rotary hook mechanism 6
[UFeed mechanism 6
d] Thread trimmer mechanism 7
d] Tension releaser mechanism 7
dl Reverse mechanism 8
d] Thread wiper 8
[9] Needle bar (left and right) mechanism types
B835 and B836 9
(13 Top feed mechanism types 8837 and B838 10
rDISASSEMBLY PROCEDURES ^ 11
\B831. B832, B835, B836. B882y
d] Cover 11
(UPresser mechanism 11
|T|Thread wiper 12
d] Rotary hook, lower shaft and
thread trimmer mechanism 12
d] Reverse mechanism 14
d] Needlebar rocking shaft mechanism 15
d] Reverseswitch mechanism 15
(assembly procedures) 16
[T|Needle bar 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 bargap
(Models 8831, 8832, 8835, 8836. 8882) 28
d] Needleand rotary hook timing adjustment 29
d] Rotary hookto needle plate gap 31
d] 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
HE Knife driving lever adjustment 42
(13 Positiondetector adjustment 43
03Corner sewing position adjustment
(8835, 8836) 43
03Timing belt replacement 47

CONTENTS [Model B837 B838]
CDISASSEMBLY PROCEDURES\ 48
VB837, B838 J
(T) Cover 48
(H Tension release lever 49
Uj Presser foot and walking bar 49
G] Needle bar and needle thread take-up 51
UlFeed assembly 51
( ASSEMBLY PROCEDURES ) 52
[0 Feed assembly 52
[O Needle bar 52
(HWalking bar and presser foot 53
[T) Tension release lever 57
[O Cover 58
/STANDARD ADJUSTMENT^ 59
\^B837, B838 J
Q]Needle and feed timing adjustment (standard) .. 59
UlFeed dog adjustment in back and forth
directions 60
UlNeedle and rotary hook timing adjustment 61
0Clearance between rotary hook and
needle plate 62
0Clearance between rotary hook and
bobbin case opener 62
0 Presser foot height adjustment 63
0 Feed dog height adjustment 64
0Vibrating 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 stroke adjustment 66
"GAUGE PARTS LIST FOR
DOUBLE NEEDLE LOCK STITCH
sSEWING MACHINES 67
( others) 75
(XlTop cover thread guide 75
UlAdjusting upper thread length 75
UlAnti-spinning spring 76
[H Bobbin 76
G]To thread bobbin
cases (8835. 8836) 76
(troubleshooting guide) 77

NAMES OF MAIN PARTS
< Model LT2-B831 >
I
<Model LT2-B832>
<Model LT2.B882>
Xv
LT2-B831
Sewing speed
Stitch length
Pfesser foot
height
Feed dog height
Needles
LT2-B832
Forlhm Forlhick
malenals I
materials
4000 spm
3000 spm
0~4 mm
0~5 mm
7 mm
Use
For thin
materials
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 1DPx5''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 order 8mm)
7 mm
1 2.7 mm
1.0 mm
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
5 mm
1.0 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
Knee lifter
1 6 mm
Feed dog height
1.0 mm
Needle
DP X 17

Treadle unit

Bi Motor pulley
Medium
LT2-B832-403A
703A
LT2-B835-403A
703A
50 Hz
60 Hz
50 Hz
60 Hz
Machine speed
4000 spm
3000 spm
Motor Pulley
Size
Part No.
1 20 Pulley
224545-000
105 Pulley
226389-000
105 Pulley
226389-000
90 Pulley
224506-001
Belt Cover
# No.
Part No.
#12-2
224547-001
#12-1
226393-001
#12-1
226393-001
Treadle Unit
H No.
Part No.
#5-38
224396-038
#5-30
224396-030
Control Box
Assembly
V
Part No.
110/220 V 100/200 V
226531-001 226426-001
110/220V 100/200V
226531-002 226426-002
Thick
LT2-B832-405A
705A
LT2-B835-405A
705A
LS2-B837-300A
50 Hz
60 Hz
50 Hz
60 Hz
Machine speed
3000 spm
3000 spm
Motor Pulley
Size
Part No.
105 Pulley
226389-000
90 Pulley
224506-001
105 Pulley
226389-000
90 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
V
Part No.
110/220V . 100/200 V
226531-002 226426-002
110/220 V . 100/200 V
226531-002 226426-002
* When ordering amotor 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 three phase machines.
*Machines and motors for voltages other than those specified above can be manufactured to order. Consult your local
dealer.
* Be sure to refer to the parts book when ordering any parts.
(2) Motor pulley change
(fr.
10 mm
-4-
Use the V-belt included together with the machine
head. After installing the belt, loosen both hexagon
nuts O. and adjust the tension of the belt. Make sure
that the correct belt tension is maintained. Then
tighten the hexagon nuts.
The belt can be depressed about 10 mm with afinger.

mm
When pulley O turns inthearrowdirection, itsrotating motion is conveyed touppershaftO toturncounterweightO-
The motion is 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 IS connected to needle bar crank rod 0.
Needle bar O moves up and down via needle bar clamp 0 which is connected to needle bar crank rod 0.
Needle bar O is guided by needle bar support O
(The arc motion is conveyed to the thread hole in thread take-up lever © via thread take-up leverslide block ©which is
connected to needle bar crank rod 0).
U] NEEDLE FEED MECHANISM
\W o
When pulleyO turns inthe arrowdirection, its rotating motionis conveyedto 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 0 and lower shaft ©.
Level feed arm © moves in the shape of arc via eccentric wheel O. 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 support © moves back and forth via needle bar rock link © and needle bar connecting rod ©.
Needle bar © which is connected to needle bar support © moves back and forth.

[U LOWER SHAFT AND ROTARY HOOK MECHANISM
1. When puiley O turns inthe arrowdirection, its rotating motion is conveyed to uppershaft O to turn timing beltwheel
upper O'
2. The motion is conveyed to timing belt wheel lower 0 via timing belt O.
3. As 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 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 Orotates via timing belt wheel lower O and lower shaft O.
Level feed arm 0 moves in the shape of an arc via eccentric wheel O. level feed connecting rod 0 and levelfeed
connecting link 0.
Feed bar 0 moves back and forth via feed rock shaft 0
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 of movements in item 5 and item 6.

d] THREAD TRIMMER MECHANISM
1.
2.
3.
5.
6.
7.
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 knifedriving lever O-
As 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 O. the motion is conveyed to knifelockarm 0 via knifemain lever
O, knife sub lever O. knife lengthadjustingIink0. knife lockleverright®and knife lockarmshaft©(rightsliderside).
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 of knife main lever O is being controlled by theshapeof knife driving cam
8. After returning movable knife solenoid O is OFF, and knife 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 knife driving lever O.
As knife main lever shaft 0 is pushed in the arrow direction, tension release lock lever O is connected with tension
release cam portion of knife driving cam O.
Rollerof tension release lock lever O is pushed in the arrow direction bytension release cam portion of knifedriving
cam O.
The motion is conveyed to tension release crank 0 via tension release connecting rod lower O, tension release crank
lower O, tension release crank upper 0 tension release connecting rod upper 0 and tension release plate 0.
As tension release crank 0 pushes presser bar lifter ®. tension disc 0 is moved via tension release bar 0. tension
release plate 0 and pin.
When solenoid O is OFF, tension disc is returned to its original position.
-7-