Tension Release Mechanism - Brother CB3-B917 Service Manual

1.MECHANICAL DESCRIPTIONS
1-8-3. Button clamp opener [B917A]
Size adjustment
plate
Button clamp opener
lever
Button clamp opener
claw

1-9. Tension release mechanism

Thread tension (Tightens
on final stitch only)
Slider
Slider
During machine
operation
Machine stopped
Sewing
Final stitch B917A
9
Button clamp
Button clamp plate cam
opener lever
129s
Auxiliary tension (Opens
at each stitch)
Rocking
132s
Final stitch
(B916A : non)
Machine stop
Thread
tension
O
O
O -> X -> O
B916A
O -> X -> X
CB3-B916A/B917A
Claw adjustment
plate
Button clamp
Main tension
tension is always kept.)
Needle bar
drive lever
133s
Auxiliary tension Main
tension
O X
Opens at each X
stitch
Differs according
to needle bar X
position
130s
Returns to
original
position
Disconnects
131s
(Thread
O-Tension discs open
X-Tension discs close