JUKI LH-4128-7, Руководство инженера

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When the clearance is large:
o The amount of disc floating in the
disc floating mechanism be-
comes insufficient and a thread
trimming error is caused.
When the clearance is small:
o The roller section comes in
contact with the thread trimming
cam and the thread trimmer
cannot function.
4) Position of the thread trimming cam and the thread trimming timing
1. Let the arm's engraved marker dot coincide with the engraved marker
dot (red) of the hand wheel .
2. In the state that the knife driving arm is keeping contact with the
stopper of the thread trimmer driving arm, push in the cam roller
and set it in the groove of the thread trimming cam .
3. In this state, turn the thread trimming cam as far as the illustrated
position. In this position (midpoint where the groove shape of the thread
trimming cam changes from straight to diagonal), tighten the tight-
ening screws (2 pcs.) of the thread trimming cam .
o Checking the thread trimming timing
1. Push in the cam roller until it assumes the posture being settled in
the cam groove.
2. Turn the hand wheel in the direction opposite to the sewing ma-
chine revolving direction and stop it where it is hooked. Confirm in this
case that the engraved marker dot (red) of the hand wheel exactly
coincides with the arm’s engraved marker dot .
o Thread trimmer cam position check
1. In the state that the thread trimmer drive arm stopper keeps contact
with the knife drive stopper , turn the hand wheel so that the
groove-state straight section of the thread trimmer cam comes to
the position of the cam roller .
2. Confirm that the cam roller does not involve any mechanical mis-
match in that position and it can be pushed in the groove of the thread
trimmer cam .
5) Clearance between the thread trimming cam and the thread loos-
ening arm
1. Push in the thread relieving arm .
2. At that time, adjust the position of the stopper so that Clearance A
of 0.5mm is secured between Face B on the right end face of the
thread trimming cam and the roller section of the thread reliev-
ing arm .
Adjustment Procedure Results of Improper Adjustment
If the thread trimming timing is
excessively advanced:
o Needle thread will come of the
needle eyelet.
o Thread trimmer will fail to
operate normally, which will
result in thread trimming failure.
o Needle thread clamp failure will
occur at the time of thread
trimming.
If the thread trimming timing is
excessively retarded:
o The needle will interfere with the
wiper.
o Thread trimming failure will
occur.
Thread trimming
timing is exces-
sively retarded.
Thread trimming
timing is exces-
sively advanced.