Setting The Timing Of The Two Thread Chainstitch Looper - Pfaff Coverlock 4772 Service Manual

22. Setting the timing of the two thread chainstitch looper

Requirement:
When the needle bar has moved 3.5 mm upwards from its lowest position, the point of the two thread
chainstitch looper 16 must be at the middle of the needle (D) (figure 39).
Check:
G Turn the handwheel in the normal direction until the needle bar is in its lowest position.
G Push the needle bar clamp (00-870 137-01) over the needle bar.
G Turn the handwheel in the normal direction until the point of the two thread chainstitch looper
is at the exact middle of the needle (D).
G Push the needle bar clamp up against the machine's housing and slightly turn the knurled
screw (figure 40).
G Turn the handwheel in the opposite direction until the needle bar clamp rests up against
the machine's housing.
G The point of the two thread chainstitch looper 16 must rest at the middle of needle (D).
G Carry out a visual check of the forward and backward movement.
Note:
Since the movement of the lower overedge looper 4 and two thread chainstitch looper 16 is
controlled by the same drive eccentric 6, the timing of the two thread chainstitch looper can not
be set at the drive eccentric 6 (figure 41).
If the movement has not been set correctly, the timing of the lower overedge looper must be
checked and/or reset as described under section 12 of the adjustment and repair instructions.
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