Brother DT4-B281 User manual

SERVICE MANUAL
FOR
DT4-B281
FOUR NEEDLE DOUBLE CHAIN
STITCHER WITH PULLER
•
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Table ofContents
[A] Model Plate Display ....................................................................................................................... 1
[B] Specifications .................................................................................................................................2
[C] Description of Mechanism .............................................................................................................3
[) Needle bar mechanism ...........................................................................................................3
~ Looper mechanism .................................................................................................................4
II] Retainer mechanism ...............................................................................................................5
[!] Feed mechanism ....................................................................................................................6
~ Presser foot lift mechanism ...................................................................................................7
@] Thread release mechanism ...................................................................................... ~- .............7
[1] Looper thread take-up mechanism .........................................................................................8
ffi] Puller mechanism ...................................................................................................................8
[2] Lubrication.............................................................................................................................9
[D] Disassembly Procedures................................................................................................................. 10
[!] Cover...................................................................................................................................... 10
--~- \
11] Presser.................................................................................................................................... 11
[1] Feeding .................................................................................................................................. 11
(!] Retainer.................................................................................................................................. 12
~ I...ooper and needle guard ....................................................................................................... 12
[§] Needle bar .............................................................................................................................. 13
[1] Upper and lower shafts .......................................................................................................... 13
[E] Assembly and Adjustment Procedures........................................................................................... 14
ITJ Upper and lower shafts .......................................................................................................... 14
III Needle bar .............................................................................................................................. 15
mLooper and needle guard ....................................................................................................... 17
@] Retainer .................................................................................................................................. 19
[I] Feeding .................................................................................................................................. 20
lEJ Presser.................................................................................................................................... 21
[1] Cover...................................................................................................................................... 23
/- .·\
---,
[F] How to Change the Roller.............................................................................................................. 24
[G] Disassembly and Assembly of the Bottom Metering Device ........................................................ 27
[li] Standard Adjustnlent ...................................................................................................................... 30
[] Needle bar height...................................................................................................................30
II] Installation position oflooper................................................................................................ 30
~ Needle and looper timing ....................................................................................................... 31
I!] Clearance between needle and needle guard .........................................................................32
!
,.---
III Installation position ofretainer ..............................................................................................32
[§] Installation position of feed dog ............................................................................................ 33
[1] Presser foot lift stroke............................................................................................................ 33
[[] Roller feed amount ................................................................................................................ 34
[2] Thread tension........................................................................................................................ 35
[ I ] Troubleshooting ............................................................................................................................. 36
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)
~- jj
From the library of: Superior Sewing Machine & Supply LLC

[A] Model Plate Display
Device Sp.ecs. Needle gauge
[!) Specifications
A Specifications
00 Plain stitching (without puller)
02 For elastic gathered waistbands
(with bottom metering device)
(with puller)
04
Forshirtfronts (with puller)
05
For waistbands (with puller)
li] - [Q Needle gauge
B:c
Needle gauge (inches)
0 I 1 Full width
3/4
0
12
Full width 1
0 I 3 Full width 1-1/8
0
14
Full width 1-1/4
0 I 5 Full width
1-1/2
0'6
1/4
- 1 -
1/4
0 : 7 3/16 - 7/8 - 3/16
o:8
1/4 - 3/4- 1/4
0 I 9
1/4 - 1/2- 1/4
1 : 0
3/16- 1 -3/16
1
~ 1
3/16 - 3/4 -3/16
[lli Device
Air Type TapeCutter
Solenoid Type Tape Cutter
- 1 -
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/
-2-
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[C] Description ofMechanism
@ The power is transmitted in the order of the following numbers.
[!] Needle bar mechanism
0 Coupler L
0 Upper shaft L
f) Thread take-up crank
Slide block
Up and down motion
t
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[1] Looper mechanism
8 Looper rod
0 Pin
tD Looper holder
Holder frame lever
Taper shaft
Pull
• Pull the plate so that the taper shaft end comes off the holder frame lever.
The spring works to
Jet the looper down this side.
-4-
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[I] Retainer mechanism
8 Retainer shaft arm
0 Retainer shaft
«;)Pin
0 Feed link
8 Retainer arm
CD Retainer ----...c!~~~~
Q) Retainer holder Right and left motion
Cl Holder shaft
-5-
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~ Feed mechanism
1. Up and down motion/Forward and backward motion
(j) Feed bracket
® Feed arm shaft
@Rod pin
@Feed shaft
@Eccentric wheel assembly
Swing
(j)
•Up and down motion
•Forward and backward motion
2. Stitch length changing mechanism
C) Feed eccentric
lUp and down motion
Turning
direction
8 Lower shaft
8 Feed rod
Press the push button 0 and tum the pulley so that the tip engages with the eccentric adjusting cam fj. Then tum the pulley
C) forward and backward to change the eccentricity of the eccentric wheel assembly Q. As a result, the feed volume will be
changed.
Press 0 Push button
C) Pulley
Alignment mark
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II] Presser foot lift mechanism
8 Presser lift M lever 0 Presser lift lever R
G Presser lift lever L
Step on the pedal
Presser lift plate
Presser bar clamp
[!] Thread release mechanism
Tension disc
Step on the pedal
G Thread release arm
8 Thread release shaft
8 Thread release plate
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[1] Looper thread take-up mechanism
8 Take-up rod
8 Pin
0 Looper thread take-up
[£] Puller mechanism
CD Puller driving lever
8 Clutch lever
Plastic gear D
Looper shaft
Take-up guide
V-belt pulley
Timing pulley D
«!) Puller eccentric wheel assembly
The feed volume ofthe puller (plastic gear) can be adjusted by changing the eccentricity of the puller eccentric wheel assembly
@). The fine adjustment can be made by changing the arm length of the puller driving lever t1 with the knob.
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[2] Lubrication
Trochoid pump
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[D] Disassembly Procedures
@ Disassemble the machine by removing the parts in the order of the following numbers.
[}] Cover
0 Turn the pulley and drain the oil in the pump.
(8 X 16)
-~
(4.37 X~) ~ m~
''~ fj) Needle
8 Presser foot
f) Loosen the screw of
presser lift stopper.
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8 Belt cover
(V-belt)
(4.37 X 23)
0 Oil pan
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l1J Presser
8 Loosen
the set screw.
(5.95)
(t Stud screw\ ~
/.
(4.37)
[I] Feeding
0 Adjusting screw ___ _..,.,.,..
thumb nut
8 Washer---
0 Presser bar clamp-____,-:---T~rfl'"''
G Presser bar ___ _,!_:---r-r-:-:;::?1C
0 Loosen the screw.
(4.37 X 9)
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Cii) Packing
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[1] Retainer
[]] Looper and needle guard
Holder nut
Looper holder
frame
f) Looper
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[§] Needle bar
C) Needle bar
~~r===~-- 8 Loosen the screw.
(6.35)
G) Washer~
Cii) Ne~dle bearing~ .-// 14\
0 Connectmg rod ~
~
0 connecting rod shaft ~
Screw (4.37~~·
• Screw (4.37)
.,
0 Needle clamp
CB Upperandlowershafts
8 Pulley
0 Timing belt
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Screw
(6.35)
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[E] Assembly and Adjustment Procedures
[!] Upper and lower shafts
Alignment mark
I
Apply grease. CD
[Selecting a proper timing belt]
Use a timing belt ofthe same code as the index on the arm
bed top. In cold areas where asingle phase, 400-W motor is
used, use the belt indicated in parentheses, e.g., (B) or (C).
(1) Slide the timing belt 0 into the arm.
(2) Attach the V-belt pulley f) onto the lower shaft 8
and lightly tighten the set screws e. Tighten the set
screw ® on the side of the rotation direction against
the screw recess on the lower shaft 8.
(3) Lightly tighten the bolt 0 (washer) until there is no
play in the axial direction ofthe V-belt puiiey 8.
* Check if the lower shaft rotates easily.
(4) Securely tighten the set screws e.
(5) Attach the plate spring 0 pressing the outer ring of
the bearing.
(6) Tighten the bolt 0.
(7) Turn the V-belt puiiey 8 so that the looper holder
frame 8 comes to the extreme rear position.
(8) Turn the upper shaftL C) so that the alignment mark
ofthe upper shaft coupling L 0 faces up.
(9) Apply grease around the bearing.
(10) When the looper holder frame is at the extreme rear
position
and the alignment mark of the upper shaft
coupling L faces up as described at steps (7) and (8),
face up the screw recess ofthe upper shaft R (!) and
pass the upper shaft R 0 into the arm through the
timing belt 0. Then pu~h the upper shaft R G until
it lightly touches the upper shaft L C), and tighten the
setscrews 4D.
(Push the upper shaft R «!) while putting the timing
belt 0 lightly onto the timing gear 8 and turning
the pulley CD • Check the screw recess of the upper
shaftR (!) by removing the set screws 4D .)
Arm bed
Timing belt
A A • (B)
B B •
(C)
c c
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(]] Needle bar
•
•
•
Set screw
Recess
Chamfer side
(1) Attach the needle bearing 8, connecting rod C) and
washer 8 to the connecting rod shaft 0. Insert them
as a setinto the thread take-up crank •· Make an
adjustment so that 0.05 to 0.07 mm clearance is
provided between the connecting rod shaft 0 and the
connecting rod C). Securely tighten the set screws.
{Tighten the set screw on the recess side frrst.)
(2) Put the cap 8 on the arm.
(3) Attach the slide block 8 to the needle bar guide $
with the slide block chamfer side positioned inside.
(4) Attach the needle bar clamp 0 to the connecting rod
C) and the slide block 8.
(5)
(6)
Pass the needle bar CD) from the upper side ofthe arm
through the needle bar clamp 0 and tighten it
temporarily.
Attach the needle clamp
CD to the needle bar G) .
(7) Attach the needle plate 8 onto the needle plate
support f1.
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I I I I
(8) Set the needle bar 0 at the highest position by
turning the pulley and attach the needles.
(9) Loosen the set screw in the needle bar clamp 0.
(10) Adjust the needle bar by turning it so that the needles
can enter the center of the needle holes of the needle
plate •.
Adjust the distance between the needle tips and the top
of needle plate to 13.9 mm when the needles are at the
extrem~_ upper position.
(11) Securely tighten the set screw ofthe needle bar clamp
0.
(12) Face the needle bar take-up e toward this side.
(13) Turn the pulley and make sure if the slide block 8 for
the needle bar guide touches the slide block felt 8
when the needle bar is 1 mm before its lowest position.
Also check if the connecting rod 8 slightly touches
the felt 0 ;or too heavy touch may cause oil leak and
too light touch may cause seizure.
(14) Remove the needles and needle plate.
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Q) Looper and needle guard
Looper gauge
~~·
::::=-------
0-0.1 mm
(1) Temporarily tighten the looper holder 0 to the looper
holder
frame f).
(2) Insert the looper 0 into the looper holder 0 until it
comes to the stop. Locate the looper so that the side
® is at the right angle (90°) to the retainer shaft 8.
Temporarily tighten the screw.
(3) Install the needles.
(4) Make an adjustment by moving the looper holder 0
right and left so that 0 to 0.1 mm clearance is provided
between the looper and the needle when the tip of the
looper 0 advances and aligns with center of the
needle. After adjustment, secure the looper holder
with the screw.
(5) Turn the pulley to move the looper 0 and make sure
that the 2 mm clearance is provided between the
looper tip and the center of the needle when the looper
0 comes to the extreme rear position.
If necessary, loosen the bolt 0 and move the looper ~
0 back and forth for adjustment.
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