Timing Of Feed Motion - Pfaff expression 2014 Service Manual

3. Timing of feed motion

Operating sequence:
When the rising needle has left 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 0.7 mm more to the rear (after-feed move-
ment).
After completing the feeding movement, the feed dog moves down under the needle plate surface
and the needle enters the fabric.
Underneath the needle plate the feed dog moves back to its basic position.
Whenever the stepping motor changes the sewing direction from forward to reverse sewing, the feed dog
must be positioned 0.3 - 0.35 mm below the needle plate surface on its way downward.
Requirement:
When the needle bar has moved 2 mm up from its lowest position (b.d.c), it must be possible to insert the
two pins of pin gauge 63-114 690-09 simultaneously in the holes of the feeding eccentric and the stud
(fig. 9).
Check:
Remove the needle.
Turn the handwheel to set the needle bar at its lowest position.
Set the spacer (63-102 600-18) onto the needle bar and push it up against the needle bar frame.
Push the needle-rise clamp (00-870 137-01) on the needle bar and tighten it lightly.
Push the 2 mm feeler gauge (00-870 136-01) with its cutout on the needle bar above the needle-rise
clamp.
Loosen the needle-rise clamp and push the 2 mm feeler gauge up against the spacer.
Tighten the milled screw of the needle-rise clamp (fig. 7).
Turn the handwheel to and fro a little.
If there is play at the feeler gauge, repeat this procedure.
Remove the 2 mm feeler gauge.
Turn the handwheel in sewing direction until the needle-rise clamp is up against the spacer (fig. 8).
Tilt the machine over backwards.
Hold the handwheel in this position while at the same time inserting the pin gauge in the holes of
feeding eccentric 5 and stud 27 (fig. 9).
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