Timing Of Feed Motion - Pfaff Select 1520 Service Manual

12. Timing of feed motion

Operating sequence:
When the rising needle has cleared the fabric, the feed dog moves up above the needle plate.
The risen feed dog pushes the fabric to the rear. Shortly before the end of the feeding motion, the take-up
lever is in its highest position (t.d.c).
At a stitch length setting of 6 mm the feed dog now pushes another 0.6 mm more to the rear (feeding
stroke).
After completing the feeding movement, the feed dog moves down below the needle plate surface and the
needle enters the fabric.
Underneath the needle plate the feed dog moves back to its basic position.
Requirement:
When the needle bar has moved 2 mm up from its lowest position (b.d.c), the line marks on the edge 34
of feeding eccentric 33 and connection rod 10 must be opposite each other (fig. 19).
Check:
Remove needle.
Turn handwheel to set needle bar at its lowest position.
Apply spacer (63-102600-18) over the needle bar and push it up against the needle bar frame (fig. 20).
Place the needle-rise clamp (00-870 137-01) onto the needle bar 30 and secure it lightly.
Place the 2 mm feeler gauge (00-870 136-01) onto the needle bar with its cutout above the needle-rise
clamp.
Loosen the needle-rise clamp and push the 2 mm feeler gauge up against the spacer.
Tighten the knurled screw of the needle-rise clamp.
Turn the handwheel back and forth slightly.
If there is play on the feeler gauge, repeat the above procedure.
Remove the 2 mm feeler gauge.
Turn the handwheel in sewing direction until the needle-rise clamp rests on the spacer (fig. 21).
Tilt the machine over backwards.
The line marks on edge 34 of the feeding eccentric 33 and connection rod 10 must now be opposite
each other.
Adjustment:
If the adjustment is not correct, remove the needle-rise clamp.
Loosen the three screws 44 in the lower belt gear.
Re-fit the needle-rise clamp and repeat the procedure as described in "Check" until the needle bar has
moved upwards by 2 mm and the needle-rise clamp rests on the spacer (fig. 21).
30