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Automatic bobbin winding (trouble and corrective measure)
Bobbin thread winding from the exclusive bobbin thread
Trouble
1
Thread fails to be wound in
bobbin.
2
Thread is not caught by the
inner hook thread guide.
3
Bobbin thread fails to cut.
4
Thread is not retained to thread
retaining plate A after completing
thread winding.
(a)
The hook cocer is not attached.
(b)
Threading to the thread retaining plate is not correct.
(c)
Retaining force of the thread retaining spring is too low.
(d)
After starting thread winding, the thread which has come out of the bobbin slit
passes the upper side of "U" letter at the top of thread retaining plate A and
comes off the thread retaining spring.
(e)
Bobbin fails to rotate.
(a)
There is a scratch on the inner hook and thread is caught with it.
(b)
Thread is caught with the inner hook detent plate and runs around.
(c)
Threading has not completed and the bobbin thread is removed by the needle
thread.
(d)
Threading has completed, but the thread cannot be drawn out since thread
end is drawn in and comes out from the entrance side.
(a)
There is a scratch on the inner hook and thread is caught with it.
(b)
Thread is caught with the inner hook detent plate and runs around.
(c)
The outer hook fixed knife is dull.
(d)
The bobbin thread tension is too low.
(e)
Tension on the side of spool for exclusive thread is too low.
(a)
Thread slackens when pushing the thread with the hook of outer hook.
(b)
A scratch on the hook of outer hook
(c)
Tension of thread retaining plate A is too high.
Cause
Corrective measure
• Attach the hook cover.
• Check whether threading to the thread retaining plate is as
shown in the threading diagram.
• Check whether threading is made to the lower side of thread
retaining plate hook.
• Adjust the height of thread retaining plate A referring to (25) -1.
Check the deflecion of thread retaining spring.
• Check the retaining force of thread retaining plate A (asm.) only.
0.64 to 0.88N (65 to 90g) wax coated thread #80.
• Check the position of thread retaining plate A hook.
• Malfunction of the gear connecting link
• Deformation of the gear connecting link plate spring.
• Correct the inner hook.
• Correct or replace the inner hook detent plate.
• Adjust the inner hook detent plate (longitudinal direction)
referring to (6). If it is excessively moved to the forward direction,
thread is caught with it.
• Same as (a) and (b) above.
• The hook cover pile is excessively tilted.
• Same as (a), (b) and (c) above.
• The feed bar pile fails to retain thread.
• Correect the inner hook.
• Correct or replace the inner hook detent plate.
• Adjust the inner hook detent plate (longitudinal direction)
referring to (6). If it is excessively moved to the forward direction,
thread is caught with it.
• Replace the outer hook fixed knife.
• Adjust the bobbin thread tension referring to (17).
• Check the thread winding tension plate or bobbin thread guide.
• The position of gear connecting link stopper is improper and
the bobbin driving gear is disengaged.
• Bobbin rises and the gear is disengaged.
• Check the inclined plane of the hook of outer hook.
• Check the retaining force of thread retaining plate A (asm.) only.
0.64 to 0.88N (65 to 90g) wax coated thread #80.
14
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