Setting The Timing Of The Two Thread Chainstitch Looper - Pfaff Coverlock 4872 Service Manual

20. Setting the timing of the two thread chainstitch looper

Requirement:
When the two thread chainstitch looper 13 moves from its left point of reversal to the right and the looper
eye has reached the needle center line "L0", the needle and looper eye should be flush (fig. 37).
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 13 is at
the exact middle of the needle "L0".
G Push the needle bar clamp up against the machine's housing and slightly turn the knurled screw (fig.
38).
G Turn the handwheel in the opposite direction until the needle bar clamp rests up against the machine's
housing once again.
G The point of the two thread chainstitch looper 13 must be positioned at the middle of needle "L0".
G Carry out a visual check of the forward and backward movement.
Note:
Since the movement of the lower overedge looper 2 and two thread chainstitch looper 13 is con-
trolled by the same drive eccentric, the timing of the two thread chainstitch looper 13 can not be
set at the drive eccentric.
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 11 of the adjustment and repair instructions!
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