Thread Trimmer Mechanism; Tension Releaser Mechanism - Brother b831 Service Manual

d] THREAD TRIMMER MECHANISM
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When thread trimming signal comes from synchronizer, solenoid O is ON and plunger O is pulled in the arrow
direction.
The motion is conveyed to knife driving pin lever O via knife driving lever O-
As knife main lever shaft O is pushed inthe arrow direction, knife main lever roller O entersknife driving cam recessO
which is connected to lower shaft O-
According to the recess shape of knife driving cam O. the motion is conveyed to knife lockarm 0 via knifemain lever
O, knife sub leverO. knife length adjusting Iink0. knife lockleverright® and knife lockarmshaft©(rightsliderside).
The motion is conveyed to knife lock arm 0 via knife link 0 which is connected to knife locklever right®, knife lock
lever left 0 and knife lock arm shaft 0 (left slider side).
Movable knife 0 which is connected to slider 0 is moved in the arrow direction.
Themovable knife 0 returns while the roller of knife main lever O isbeing controlled by theshape ofknife driving cam
8. After returning movable knife solenoid O isOFF, and knife main lever roller O isreleased from knife driving cam recess
ID TENSION RELEASER MECHANISM
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Tension
release
cam
Roller
When thread trimming signal comes from synchronizer, solenoid O is ON and plunger O is pulled in the arrow
direction.
The motion is conveyed to knife driving pin lever O via knife driving lever O.
As knife main lever shaft 0 is pushed in the arrow direction, tension release lock lever O is connected with tension
release cam portion of knife driving cam O.
Roller of tension release lock lever O is pushed in the arrow direction by tension release cam portion of knifedriving
cam O.
The motion is conveyed to tension release crank 0 via tension release connecting rod lower O, tension release crank
lower O, tension release crank upper 0 tension release connecting rod upper 0 and tension release plate 0.
As tension release crank 0 pushes presser bar lifter ®. tension disc 0 is moved via tension release bar 0. tension
release plate 0 and pin.
When solenoid O is OFF, tension disc is returned to its original position.
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