HIGHLEAD GC20688-DC User manual

Parts Catalog
SHANGHAI HUIGONG NO.3 SEWING MACHINE FACTORY
GC20688-DC/GC20688-BDC
Compound-Feed, Heavy Material Lockstitch Sewing
Machine With Edge Cutter
Instruction Manual

----- CONTENTS -----
1. PRECAUTIONS BEFORE STARTING OPERATION···············································································1
1) Safety precautions····································································································································1
2) Precaution before Starting Operation····································································································1
3) Precaution for Operating Conditions·····································································································1
2. SPECIFICATIONS ·········································································································································1
3. PREPARATION BEFORE STARTING TO OPERATE ·············································································2
1) Connection of control box ·······················································································································2
2) Oil pan·······················································································································································3
3) Operation panel········································································································································3
4) Adjusting the needle stop position··········································································································3
5) Lubrication···············································································································································4
4. HOW TO USE THE MACHINE ···················································································································4
1) Threading··················································································································································4
2) Adjusting of the thread regulator···········································································································5
3) Adjusting of upper thread tension········································································································ 5
4) Winding the lower thread························································································································5
5) Threading the lower thread·····················································································································5
6) Adjusting the lower-thread tension········································································································6
7) Installing the needle·································································································································6
8) Alternating presser foot movement amount··························································································6
9) Adjusting the presser foot pressure······································································································ 6
10) Adjusting the stitch length ······················································································································6
11) Using the manual switches ······················································································································7
12) Cleaning····················································································································································7
13) Lubrication···············································································································································7
14) Adjusting the trailing length after thread trimming·············································································8
15) Back tacking·············································································································································8
16) Adjusting the feed dog·····························································································································9
17) Adjusting the needle bar height··············································································································9
18) Adjusting the gap between the needle and the rotary hook tip··························································10
19) Adjusting of the needle and the hook timing·······················································································10
20) Hook protection······································································································································10
21) Adjusting the needle and feed mechanism timing···············································································11
22) Adjusting the opener position···············································································································12
23) Adjusting the presser foot height··········································································································12
24) Adjusting the alternating presser foot movement amount·································································13

25) Adjusting the presser foot timing ·········································································································14
26) Adjusting the fixed knife position·········································································································15
27) Adjusting the thread holding spring position······················································································15
28) Adjusting the knife timing position······································································································15
29) Adjusting the driving knife height········································································································15
30) Adjusting the driving knife stop position·····························································································16
31) Adjusting the driving knife operating position ···················································································16
32) Adjusting the thread trimming timing·································································································17
33) Safety clutch ···········································································································································17
34) Regulate the atmospheric pressure······························································································18
5. HOW TO USE THE VERTICAL CUTTER·······························································································18
1) Idle of the knife when the vertical cutter is turned off···························································19
2) Timing of the deactivation of the knife ·····················································································19
3) Position of the release block········································································································· 19
4) Lubrication of the eccentric ·········································································································19
5) Stroke of the knife ···························································································································19
6) Timing of knife movement ············································································································20
7) Knife overlap ····································································································································20
8) Setting and pressure of the knife blades ···················································································20
----- PARTS LIST -----
A. ARM BED AND ITS ACCESSORIES···········································································································21
B. THREAD TENSION REGULATOR MECHANISM ··················································································25
C. SEWING MECHANISM································································································································28
D. PRESSER FOOT MECHANISM··················································································································31
E. UPPER FEED LIFTING ROCK SHAFT MECHANISM···········································································34
F. STITCH REGULATOR MECHANISM········································································································37
G. FEEDINGAND FEED LIFTING & ROTATING HOOK SHAFT MECHANISM··································40
H. HOOK SADDLE MECHANISM (RIGHT)··································································································43
I. OIL LUBRICATION MECHANISM ···········································································································47
J. ACCESSORIES················································································································································50
K. PNEUMATIC CONTROL MECHANISM···································································································52
L. KNIFFE MECHANISM ·································································································································54

—1 —
1. PRECAUTIONS BEFORE STARTING OPERATION
1) Safety precautions
(1) When turning the power on, keep your hands and fingers away from the area around/under the
needle and the area around the pulley.
(2) Power must be turned off when the machine is not used, or when the operator leaves his/her seat.
(3) The power must be turned off before tilting the machine head, installing or adjusting the machine, or
when replacing.
(4) Avoid placing fingers, hairs, bars etc. nears the pulley, bobbin winder pulley, when the machine is
operation. Injury could result.
(5) Do not insert fingers into the thread take-up cover, under/round the needle, or pulley when the
machine is in operation.
(6) If a mini motor cover, finger guard, and/or eye guard are installed, do not operate the machine
without these safety devices.
2) Precaution before starting operation
(1) If the machine's oil pan has an oil sump, never operate the machine before filling it.
(2) If the machine is lubricated by a drop oiler, never operate the machine before lubricating.
(3) When a new sewing machine is first turned on, verify the rotational direction of the pulley with the
power on. (The pulley should rotate counterclockwise when viewed from the pulley.)
(4) Verify the voltage and (single or three) phase with those given on the machine nameplate.
3) Precaution for Operating Conditions
(1) Avoid using the machine at abnormally high temperature (35℃or higher) or low temperatures (5℃
or lower). Otherwise, machine failure may result.
(2) Avoid using the machine in dusty conditions. Avoid using the machine in areas where too much
electrical noise, resulted from the high-frequency welder and others, is generated
2. SPECIFICATIONS
Item GC20688-DC GC20688-BDC
Max. Speed 3000rpm 2800rpm
Stitch length 0 to 6mm 0 to 6mm
Needle bar stroke 34mm 34mm
By hand 9 mm 9 mmPresser foot
clearance By knee 16 mm 16 mm
Rotating hook 1.6 times 2.5 times
Needle DP×17 #18-#25 DP×17 #18-#25
Presser foot alternation 1-7mm 1-7mm
Auto presser foot lifter Pneumatic Pneumatic
Oil lubrication method Automatic lubrication Automatic lubrication
Bed dimensions 300×120 mm 300×120 mm
Needle gauge（mm）3 8
If sewing with stitch length of 6 mm or more, set the sewing speed to 2000 rpm or less.

3. PREPARATION BEFORE STARTING TO OPERATE
1) Connection of control box
It shows the connection of the
electrical wires of the whole machine
on the right picture.
When the machine needs to be
assembled, each line should be linked
to the right joint according to the
instruction of the picture.
All the pins on the control box
have signals of function showing, and
usually, different wires have different
kinds of joint.
Caution: the pin of synchronizer wire is
the same with another two external pins
and if there is a misconnection, the
synchronizer might be burn.
When connecting the pipes, please check the
joint at the picture of the whole machine above
as reference.
And also there have an instruction mark of
each joint of the solenoid at the setting board.
—2 —

2) Oil pan
(1) Install the oil pan 3 to the underside of the worktable 1 in the place shown in the illustration using the
nails 2.
(2) From front view, the oil pan 3 to the side is 60mm; from right view, the oil pan 3 to the side is 80mm.
3) Operation panel
—3 —
(1) Install the operation panel 1 to the set
plate 2 with the three screws 3.
(2) Install the set plate 2 to the back of the
machine arm with the two screws 4.
4) Adjusting the needle stop position
(1) Adjusting the needle up stop position
When the sewing machine stops in the
needle up stop position (the stop position of trimming) and the treadle is pressed back, the red mark on the
pulley should be consistent with the mark on the belt cover A. Adjust as follows:

a. Turn off the power switch.
b. Loosen the screw 4, and then remove the cover 3.
c. When the red mark stops in a position over the mark on the belt cover, the needle up stop position disc 1
should be turned in the opposite direction as the direction of machine pulley rotation. When the red mark stops
in a position under the mark on the belt cover, Turn the disc 1 in the same direction as the pulley rotation
direction.
(2) Adjusting the needle down stop position
When the sewing machine stops in the needle down stop position, the black mark on the pulley should be
consistent with the mark on the belt cover A. Adjust as follows:
a. Turn off the power switch.
n a position over the mark on the belt cover, the needle down stop position
disc 2 s ion of machine pulley rotation. When the black
mark stops
is no need to loosen the screw 5, when turning the discs.
5) Lubrication
d
“FULL”. The .
USE THE MACHINE
1) Threading p
b. When the black mark stops i
hould be turned in the opposite direction as the direct
in a position under the mark on the belt cover, Turn the disc 2 in the same direction as the pulley
rotation direction.
c. After adjusting, install the cover 3, with screw 4.
Note: There
Before the new machine is used, please loosen the screw 2 and
full the oil into the oil case. Set the oil level between “EMPTY” an
n replace oil-filling screw 2
4. HOW TO
Raise the thread take-up lever to its highest position and thread the u per thread in the following order.
—4 —

—5 —
2) Adjusti g of the thread regulator
The th d regulator 9 (see the right picture) regulates the amount of needle thread necessary for stitch
formation. The setting depends on the following factors: material thickness, yarn characteristics and stitch
length.
The thread regulator is fitted with slots for this purpose. Moving in the “+”direction increases the quantity
of needle th ad; Moving in the “-”direction reduces the quantity of needle thread.
3) Adjusting of upper thread tension
Tensio ould be as low as possible. The crossover point should be in the center of the material. Upper
thread tension can be adjusted by thread tension nut 4 and 5 (see the picture of above). Turn the thread tension
nut clockwi to increase the needle thread tension. Turn the thread tension nut counter-clockwise to decrease
the needle th ead tension.
re, and wind the end of the thread clockwise
arou
n
wind
ound on, remove
the b nife 3.
5)
read is unwound from it moves in the opposite direction
to th
6, pass the thread through slit 4 and pull about 3 cm
pass the thread through the flap’s guide 5.
n
rea
re
n sh
se
r
4) Winding the lower thread
(1) Place the bobbin onto the bobbin winder shaft.
(2) Pass the thread for winding thread as shown in
the figu
nd the bobbin several times.
(3) Push the bobbin presser 1 toward the bobbin.
(4) The operation will automatically stop whe
ing is completed. The amount of thread wound
onto the bobbin should be a maximum of 80% if the
bobbin capacity. The amount of thread would be
regulated by screw 2.
(5) After the thread has been w
obbin and cut the thread with the thread-trimming k
Threading the lower thread
(1) Raise flap 1 and remove the empty bobbin.
(2) Insert bobbin 2 in such a way that when the th
e gripper.
(3) Pass the thread through slit 3 and below spring
through.
(4) Close flap 1 and

6)
he lower-thread tension should be set in accordance with the type of seam required. Adjust the tension
with screw 7. (See the picture of above)
Adjusting the lower-thread tension
T
—6 —
7)
e sure to turn off the power.
alance wheel by hand to raise the needle bar to its
high
3) Hold the needles so that the two needles side with the long
grooved (faces each other), and insert it as deeply as it will go into
the needle clamping holes( model GC20688-2-D);Hold the needle
to its side with the long groove side(left),then insert the needle as
deeply as it will go into the needle clamping hole(model
GC20688-1-D).
screw.
8)
presser foot can be adjusted within the range
movement dial 1.
foot pressure should be set as
o that the
dial
eed adjustment dials 2 and 3 can be used to set two diff
Installing the needle
Note: Before attach needle, b
1) Turn the b
est position;
2) Loosen the needle clamping screw；
4) Tighten the needle clamping
Alternating presser foot movement amount
The alternating movement amount for the inner presser
foot and the outer
of 1-7 mm using the alternating presser foot
Turn the alternating presser foot movement dial 1 clockwise or
counterclockwise to align the mark. (MIN. A, B, C, D, E, F
MAX. )
9) Adjusting the presser foot pressure
The presser
weak as possible, but strong enough s
material does not slip. If the presser-adjusting
1 is turned clockwise, the presser foot
pressure will become stronger, and if it is turned
counterclockwise, the pressure will become
weaker.
10) Adjusting the stitch length
The f erent types of stitch length. (See the picture of

above) Use feed adjustment dial 2 to set the big s
—7 —
titch length. Use feed adjustment dial 3 to set the little stitch
lengt he two stitch lengths each time the stitch length change
only while the switch 1 is being pressed.
the switch 3 is pressed when either start back tacking or
ON at the operation panel,
, The needle will move up to the needle up stop position from down stop
(1)
(2)
(3)
13) L
(1)
ove oil-filling screw 2 and pour in oil. Check oil l
must be between “EMPTY” and “F
years.
ould be checked and corrected after running-in.
k
itive lubrication
h. The sewing machine will switch between t
switch is pressed.
11) Using the manual switches
(1) Quick reverse switch
Back tacking is carried out during sewing
(2) Auto back tacking select switch
If
end back tacking has been set to
back tacking is canceled for the first time only. Furthermore,
if the switch 3 is pressed when neither starting nor end back
tacking has been set, back tacking is carried out for the first
time only.
(3) Needle up or down switch
If the switch 4 is pressed
position or move down to the needle down stop position from up stop position.
12) Cleaning
The area around the feed dog and the hook should be cleaned ev
Remove any thread scraps from inside the rotary hook.
Keep the control box clean.
ubrication
Check the oil level at the sight glass 1 every week. If the oil
enough, rem
ery day.
is not
evel at
ULL”.
sight glass 2. The oil level
Replace oil-filling screw 2. After running for 500 hours since buying
the new sewing machine, the oil must be changed. Then change the oil
every two
(2) The oil quantity is pre-set at a relatively high level in order to ensure
adequate lubrication during running–in. This setting sh
(approx. 50 hours). The hoo
is to have pos
with the least possible
amount of oil. Let the sewing
machine run approx.2
minutes. And run in intervals.

Hold a piece of paper next to the hook and check if sufficient oil is spun oil onto the paper. Remove
The hook lubrication is preset. Attach cover plate 2 again. Setting the hook lub
(3) Lubricating wicks and felt (see the picture of above)
n
7
(4)
14)Adjusting the trailing length after thread trimming
e te of the
ced; creased.
15)
rse sw n will
on wi
cover plate 2. Loosen screw 3 until the tube 1 no longer moves. This is the case when the tube is in the
center of the drilled hole. Turn screw 3 in until the tube movement just starts and then a 1/8 turn farther.
rication with screw 3.
Checking the lubrication oil.
Turn on the power switch. Depress the treadle gently and check that the oil level rises in the oil sight
glass.
a. The wick 1 leading from the oil sump to the oscillating crank 4 must be fixed between the groove 2 i
the arm and the spring 3 of the recirculation wick.
b. When the oil satchel is changed, the flock side should be faced to connecting plate 10. The oil wick
and 8 should be set between the oil satchel 9 and plate 8.
Adjust by turning the pre-tensioner 1. If th
threads trailing from the needle tips will be redu
Back tacking
When the reverse lever 1 or the quick reve
be reversed. When it is released, the feed directi
nsion of the pre-tension is increased, the lengths
if the tension is reduced, the lengths will be in
itch is pressed during sewing, the feed directio
ll return to normal.
—8 —

16)Adjusting the feed dog
settings. Then adjust as follows so that the feed dog 1 is
he needle plate 2) when the needle bar is at its lowest
is at its highest position.
gs. Then
e setting surface of the needle
plate 2 to
need
m the setting surface of the needle
1 is 18.5mm when the
need sition.
Set the feed adjustment dials to the minimum
at its highest position (0.5mm above the top of t
position.
(1) Turn the machine pulley to set the feed dog 1
(2) Loosen the screw 3.
(3) Adjust the feed dog’s height.
(4) Tighten the screw 3.
17)Adjusting the needle bar height
Set the feed adjustment dials to the minimum settin
adjust so that the distance from th
the end of the needle bar 1 is 18.5mm when the
le bar 1 is at its lowest position.
Set the feed adjustment dials to the minimum settings. Then
adjust so that the distance fro
plate 2 to the end of the needle bar
le bar 1 is at its lowest po
(1) Remove the face plate.
(2) Set the feed adjustment dials to “0”.
(3) Turn the pulley to set the needle bar 1 to its lowest
position.
—9 —

(4) Loosen the screw 3 and then move the needle bar 1 up or down to adjust so that the distance from the
tting surface of the needle plate 2 to the end of the needle bar 1 is 18.5 mm.
p between the needle and the rotary hook tip 1 is 0.1 mm.
t the level of the middle of the needle. Then
19)Adjusting of the needle and the hook timing
(1) Set the stitch length to “0”.
(2) Remove the needle plate.
(3) Overturn the arm.
(4) Loosen the screw 1
(5) Turn the machine pulley to raise the needle bar from its low
position to the point that the needle rises 2mm.
(6) Turn the rotary hook to align the rotary hook tip with the
center of the needle.
(7) Tighten the screw 1.
20) Hook protection
In looping stroke position the needle must abut on the hook
se
(5) Tighten the screw 3, install the face plate.
18)Adjusting the gap between the needle and the rotary hook tip
The ga
Set the rotary hook tip a
adjusting the gap as follow:
(1) Loosen the screws 2 and 5 (see the picture of below).
(2) Set the hook base 6 to the fit position.
(3) Rotate the adjusting plate 3, let the hook base 6 depend on the bed
plate 4.
(4) Tighten the screws 2 and 5.
—10 —

p
11 ——
rotection 1 without being displaced.
looping stroke position the hook tip is at the level of
th eedle against hook protection 1 manually. The needle should not touch the
dle and feed mechanism timing
tion
west position. Then adjust so that the needle and the feed dog do not move even when the reverse lever
r cover 1.
ent dial to the maximum
settin
rn the lower feed cam 3 gradually until it is at the position where the needle and the feed dog do not
mov oved up and down.
n
the feed adjustment dials to the minimum settings. Then adjust as follows so that the feed dog 1 is at
its highest position (0.5mm above the top of the needle plate 2) when the needle bar is at its lowest position.
a. Loosen the two screws 3
b. Turn the machine pulley to set the needle bar to its lowest position.
c. Turn feed cam 4 to align the point 5 of feed cam 4 with the centerline of feed rod 6
Move needle in looping stroke position by pulley. In
e middle of the needle. Press n
hook tip.
21)Adjusting the nee
(1) Horizontal feed direc
Set the feed adjustment dials to the maximum settings. Then turn the machine pulley until the needle bar is
at its lo
is moved up and down at this time.
a. Remove the bed uppe
b. Set the feed adjustm
gs.
c. Loosen the two screws 2.
d. Turn the machine pulley until the needle bar
is at its lowest position.
e. Tu
e even when the reverse lever is m
f. Tighten the two screws 2.
(2) Vertical feed directio
Set

e stopper 4 of the inner rotary hook 2 is 0.5-0.7
mm closest position to the
(2) Turn the machine pulley to move the opener 1 in
direc the
1 as
close
ner
rotary he
clea o
the
(5) Tighten the screw 6.
(6) Turn the machine pulley to move the opener 1 in
screw 5.
23) Adjusting the presser foot height
The standard height of the outer presser foot 7 is 9 mm bar 1.
(1) Remove the belt cover.
(2) Loosen the presser adjusting screw, to release the presser foot
d. Tighten the screws 3
22）Adjusting the opener position
Adjust so that the clearance between the needle plate
3 and th
when the opener 1 is at its
inner rotary hook 2.
(1) Turn the machine pulley to move the opener 1 in
direction “a” (opening direction), and then loosen the
screw 5
f
tion “b” (closing direction), and then loosen
screw 6.
(3) Turn the machine pulley to move the opener
to the inner rotary hook 2 as possible.
(4) While pressing the opener 1 against the in
hook 2 with your finger, adjust so that t
rance between the needle plate 3 and the stopper 4
inner rotary hook 2 is 0.5-0.7 mm.
direction “a” (opening direction), and then tighten the
when it is raised by the presser lifter
pressure.
—12 —

(3) Raise the presser lifters bar 1 and then loosen the screw 2.
(4) Move the outer presser bar up or down to adjust so that the height of the outer presser foot 7 is 9 mm.
he presser lifter shaft so that there is no play in the thrust direction, tighten the screw 2.
st the presser foot pressure.
ting presser foot movement amount
lowing adjustment to set the
maximum alternating movement amounts for the inner
presser foot 1 and outer presser foot 2 to the maximum of 7
mm.
a. Remove the upper plate.
b. Remove the adjusting bracket 3.
c. Loosen screw 5 of adjusting bracket collar 4.
d. Adjust the adjusting bracket collar 4. If the
adjusting bracket collar 4 is be installed at the highest
position, the alternating presser foot movement amount is
1-6mm. If it is at the lowest position, the alternating presser
ghten the screw 5.
ver 7 to
outer presser foot 2 moveme
(5) While the stopper pin 6 is touching against the notch B in the presser foot lifter connection 5 and while
pushing t
(6) Turn the presser adjusting screw to adju
(7) Install the belt guards.
24)Adjusting the alterna
(1) Maximum alternating presser foot movement amount. Carry out the fol
foot movement amount is 1.6-7mm.
e. Ti
f. Install the adjusting bracket 3.
d. Loosen the bolt 6 and turn connecting le
adjust so that the distance from the outer edge of the arm to
the outer edge of the pin 7 is 78 mm at this time. Then tight
the alternating presser foot movements dial to the “min.” posi
(2) Inner presser foot 1 and
en the bolt 6. (When installing the upper plate, set
tion.)
nt amounts. Carry out the following adjustment to
d outer presser foot 2 equal when the presser feetmake the movement amounts for the inner presser foot 1 an
—13 —

are lo ned.
um
ey toward you to align the
tip o dog with the top
of th
e tip of the needle should move away from the
feed
(1) Remove the upper cover 4.
(2) Loosen the two screws 1.
(3) Turn the machine pulley until the needle tip and the feed
dog’s up face is the same plane.
e point of
ternating
wered and the machine pulley is tur
a. Set the feed adjustment dials to the maxim
settings.
b. Open the cover 4
c. Turn the alternating presser foot movement dial to
the “B” position.
d. Loosen the screw 3
e. Turn the machine pull
f the needle and the top of the feed
e needle plate.
f. Move the connecting lever to adjust so that both the inner presser foot 2 and outer presser foot 1 are in
contact with the top of the needle plate at this time. Then tighten the screw 3.
25)Adjusting the presser foot timing
When the presser feet are lowered and the machine pulley is
turned toward you. The inner presser foot should touch the feed
dog before the needle arrives at the feed dog. Then when the
needle lifts up, th
dog before the inner presser foot moves away.
(4) Turn inner presser cam to adjust so that th
inner presser cam is facing straight up.
(5) Tighten the screws 2.
(6) When installing the upper plate, set the al
presser foot movement dial to the “MIN.” position.
—14 —

26)Adjusting the fixed knife position
The distance from the groove of slide plate to the fixed knife 1 should be 26 mm. Furthermore, the
le plate to the left edge of the tip of the fixed knife 1 should be 4 mm.
Loosen the two bolts 2.
) Adjust the position of the fixed knife 1, and then tighten the bolts 2.
7)Adjusting the thread holding spring position (see the picture of above)
The thread holding spring 1 holds the lower thread after thread trimming to prepare it for the next sewing
peration. The clearance between the thread holding spring 1 and the side of the fixed knife 2 should be 1.4-1.6
m.
(1) Loosen the two screws 3.
(2) Move the thread holding spring 1 to adjust its
position, and then tighten the screws 3.
28)Adjusting the knife timing position
After adjusting the position of the fixed knife 1, adjust
the knife timing position.
Adjust so that the driving knife 1 starts touching the fix
knife at a position 5.5 mm along the front edge of the
knife 1.
(1) Loosen the two bolts 3 and 4.
(2) Move the driving knife 1 to the left or righ
(3) Then tighten the bolts 3 and 4.
29)Adjusting the driving knife height
The clearance between the lower blade edge of
lower surface of the inner rotary hook should be 0.3-0.
(1) Loosen the two screws 2 and 5.
distance from the edge of the need
(1)
(2
2
o
m
ed
driving
t to adjust its position.
the driving knife 1 and the
4mm.
15 ——

(2) Move the driving knife shaft 6 up or down to adjust the position of the driving knife 1.
16 ——
(3) Tighten the screws 2 and 5 on the setting collars again.
30)Adjusting the driving knife stop position
The distance from the blade of the fixed knife 2 to the end of the driving knife 1 should be 0.5mm when
the driving knife 1 has moved as far as possible toward the fixed knife 2.
(1) Tilt back the machine head.
(2) Turn the machine pulley to move the roller 6 of the driving knife arm 5 to the outermost side (right side)
of the thread trimmer cam 7.
(3) Loosen the bolt 4.
(4) Move the driving knife 1 so that the distance between the blade of the fixed knife 2 to the end of the
driving knife 1 is 0.5 mm, and then tighten the bolt 4.
31)Adjusting the driving knife operating position
The standard distance from the left side of driving knife arm 1 to the screw tip on the plunger 2 of the
thread trimming solenoid is 1 mm. The clearance between the outermost side (right side) of the thread trimmer
cam 5 and the roller 6 of the driving knife arm should be 0.1 mm.
(1) Overturn the arm.
(2) Loosen the bolt 3
(3) Turn the plunger 2 of the thread trimming solen ving knife
arm 1 to the screw tip on the plunger 2 of the thread tri bolt 3.
oid so that the distance from the left side of dri
mming solenoid is 1 mm, and then tighten the

(4) Loosen the bolt 4.
(5) Set the plunger 2 to the position where it projects as
far as possible to the left.
(6) Turn the machine pulley to move the roller 6 of the
driving knife arm to the outermost side (right side) of the
thread trimmer cam 5.
(7) Move the roller 6 so that the clearance between the
outermost side (right side) of the thread trimmer cam 5 and
the roller 6 is 0.1mm, and then tighten the bolt 4.
32)Adjusting the thread trimming timing
The center of the pin 1, the center of the reference hole
3 an
point on the pulley and
ey until the white point on the
e belt cover are in a straight line.
(4) Turn the thread trimmer cam 2 to adjust the position of
e thread trimmer cam 2 so that the center of the pin 1, the
enter of the reference hole 3 and the center of the roller 4 of
e driving knife arm are in a straight line.
(5)Tightenthebolts5.
33)Safety clutch
The standard safety clutch 2 in the lower toothed belt wh
amaged in case of thread jamming in the hook path. When the
out.
d the center of the roller 4 of the driving knife arm
should be in a straight line when the thread take-up lever is at
the highest position. (The white the
point on the belt cover are in a straight line.)
(1) Turn the machine pull
pulley and the point on th
(2) Overturn the arm.
(3) Loosen the three bolts 5
th
c
th
eel protects the hook from being displaced or
hook is blocked, the safety clutch 2 must comed
— 17 —