4. ADJUSTMENT
RH-981A
76
4-25. Adjusting the rotating centers of the needle bar and the looper base
The rotating centers of the needle bar and the looper base are adjusted before shipment from the factory.
When disassembling the machine or exchanging parts such as the needle bar gear assembly, the needle bar, and
looper base, adjust the clearance between the needle and the point of the looper so that it does not change through
360
o
.
Before adjusting the position of needle bar bush U, be sure to check there is no gap between the needle bar gear (1)
and needle bar gear support A (2).
1. Raise the needle bar gear (1) using your fingers to
check the loseness.
Note:
If the looseness is great, the center of
rotation can not be adjusted.
2. Loosen the two bolts (3), and adjust needle bar gear
support A (2) so that the needle bar gear assembly
can rotate smoothly without gap.
3. Loosen the two bolts (4), and adjust needle bar gear
support B (5) in the same manner as above.
Note:
When needle bar gear support A (2) or
needle bar gear support B (5) is raised
excessively, the looper base may be in an
inappropriate position.
When the looper base is at 360
o
where the needle bar can move lightly up and down, adjust the position of needle
bar bush U (7).
Loosen the three bolts (6) a little, and tap on the needle
bar to adjust the position of needle bar bush U (7).
* Adjust the back and forth movement of needle bar
bush U (7) so that the clearance between the needle
and the point of the looper is not changed when the
looper base is at 0
o
and 180
o
.
Adjust the sideways movement of needle bar bush U
(7) so that the clearance between the needle and the
point of the looper is not changed when the looper
base is at 90
o
and 270
o
.
Note:
If the needle penetration movement is
adjusted to one point, the clearance between
the needle and the point of the looper will not
be fixed.
No looseness
Press manually.
3830Q
3831Q
