JUKI LH-4128-7 Engineer's Manual page 69

(1) Removal of the needle bar rocking base
1. Remove top cover
(2 screws), presser stroke adjusting screw
2. Loosen the connecting screws
3. Remove the right and left unilateral needle changeover solenoids
on the right and left of the needle drive crank. Then, remove the left thrust collar of the needle driving shaft
(2 screws).
4. Draw out the left needle driving shaft
5. Remove presser bar connector
presser , presser bar
base fulcrum shaft
6. Remove needle bar rocking base
fulcrum shaft , and rocking arm
(2) Installation of the needle bar rocking base
1. Insert needle bar rocking base
driving arm , needle bar rocking base fulcrum shaft
touches the frame.
2. Insert left needle driving shaft
3. Taking a thrust for needle bar rocking base
setscrews of rocking fulcrum shaft
rocking base , make fine vertical adjustments of the fixing position for rocking fulcrum shaft base
4. Checking the thrust for needle bar rocking base
completion of fixing, confirm without fail that needle bar rocking base
and left. Also confirm that there is no torque in rocking Direction B.
5. Moving the needle bar up and down, tighten needle driving arm connecting screw
positioning of needle driving arm
the screw tightening torque is insufficient, this can be a cause of destruction in needle driving arm
Confirm that the needle bar torque is kept light after screw tightening.
[2.9N•m (300g or below)]
If the torque seems to be too much, such a problem may have resulted from the shifting of needle driving arm
to the right or left at the time of screw tightening.
6. Secure the needle bar height [Refer to 5.- (1) -3] Needle bar height.] and tighten the right and left connecting
screws of needle driving crank
[Screw tightening torque: 5.9N•m (60kgf•cm)] If the screw tightening torque is too much, this can be a cause of
destruction in needle driving arm
7. Install right and left unilateral needle changeover solenoids
[Refer to Items 5 and 6 of 5.- (11) Needle bar stroke adjustment.]
8. Insert presser bar
bar in the position where the distance between needle bar and presser bar
dimension specified in [5.-(1)-1] Initial position of the needle bar].
9. Install presser bar connector
screws), and presser
can slide smoothly without any torque.
In addition, in regard to the fixing position for presser bar connector
presser rise with presser lifting lever
10. Install thread take-up lever guard
holder (2 screws), face plate
(3 screws), stop plug
oon the right and left of the needle driving arm
in the direction of the face section.
, presser adjusting spring
, and rocking fulcrum shaft base
and rocking arm .
. At that time, remove right needle driving arm
. In this case, a uniform force should be exerted on these three parts.
in position. At that time, exert a uniform force on the three parts of right needle
, secure a proper thrust, and fix thrust collar
. If a torque is generated in the rocking direction
settles in natural position. [Screw tightening torque: 5.9N•m (60kgf•cm)] If
.
.
. In the state of needle bar lower dead point and pitch 0, tighten the setscrew of the rocking
, presser bar
. When fixing the presser bar connecting guide
stays around 5.2 to 5.5mm.
(2 screws), presser stroke adjusting screw
(3 screws), and top cover
(2 screws), face plate
, cap , and rocking base thrust holder
(8 screws) and loosen connecting screws
, presser bar connecting guide
(2 screws). Then, loosen setscrews of rocking
, and rocking arm
, loosen two screws
, fix rocking base thrust holder
.
, presser adjusting spring
(3 screws).
– 65 –
(3 screws), thread take-up lever guard
(2 screws).
.
, needle bar rocking base
until thrust plate
(2 screws).
of rocking fulcrum shaft base
B
(2 screws). After the
is free from rattling in Direction A, right
where the right and left
becomes identical with the
, presser bar connecting guide
, make sure that presser bar connector
, make adjustments so that the amount of
, cap , rocking base thrust
(2 screws),
enters and
and two
of the needle bar
.
.
(2