JUKI LK-980 Series User Manual

V. DETAILS OF ADJUSTMENT
(1) Adjustmentfor starting&stopping (Clutch and Stop-motion mechanism)
(1) Method of adjustment
1) When the machine will not run at a highspeed ;
A. Mechanical friction is too great.
If excessive friction is produced by tight engagement of the worm gears or other parts, the important parts in
the machine including the cork linings will beheatedup and wornout. Guard against excessive friction.
B. The driving pulley pressing plate doesnot work properly.
In this case, the driving pulley will slip and will not drive the machine at a high speed. Adjust it according to
standard adjustment (6).
C. The stop-motion connecting pin is not properly adjusted.
The machine will not run at a low speed, if the idling period of the brake cork ring is longer than that of the
standard period stipulated in standard adjustment (7).
D. If stop-motion ball ® , shown in the Structural Drawing of the Clutch Component (p. 26), accidentally
comes away from the main shaft, the clutch surface can notbe aligned properly. Therefore, prevent the ball
from fallingby applying grease to the main shaft beforehand.
2) When the machine fails to start:
A. If the starting lever stopper isnot properlypositioned,
the machine may not start or may start to run at high
speed immediatelyafter the pedal is depressed. Adjust
the starting lever stopper so that it is actuated when
there is a 1 mm (3/16") clearance, between the stop-
motion regulating cam and the stop-motion regulating
cam roller(Fig. 40) whenoperatingat low speed.
B. If unusual load is produced in the machine, it may
suddenly stop when changing running speed from low
to high. Adjust the machine by removing the cause of
such a mechanical load.
3) When the machine will not run at lowspeed :
A. If it is due to
excessive friction produced by the
machine mechanism, remove the cause.
B. If oilor grease on the cork surface causes the cork rings
to slip, clean the cork surfacewith alcohol (do not use
thinneror trichlene, as thesemay damage the cork).
C.
Check to see if the driving pulley pressing plate is
correctly positioned accordingto standard adjustment
(6).
4) Whenunusual sound is produced;
A.If unusual sound is produced only at the time of low speed operation before or after starting or stopping, it
means that the stop-motion ball has been scratched dueto inadequate adjustment, as mentioned instandard
adjustment (7).
If critically damaged, the ballmust be replaced.
B. Concerning standard adjustment (3), if white line
No. 2 on the stop-motion hook enters too far into the
periphery of the brake ring, the hook will hit the
stop-motion regulating cam and make a click.
C. If edge ® of the driving plate isworn out, the thread
trimming cam will hit the cam roller intermittently
producing a click and shaking the thread trimmer
knife. Adjust as per standard adjustment (3). If edge
(3) of the driving plate has been critically deformed,
replace the driving plate(Part No.B2624-980-000).
- 23 -
Driving plate
o
Starting lever stopper
Fig. 40
Fig. 41
From the library of: Superior Sewing Machine & Supply LLC

JUKI LK-980 Series Specifications

General

Brand	JUKI
Model	LK-980 Series
Category	Sewing Machine
Language	English