Timing Of Feed Motion - Pfaff creative 7550 Service Manual

3. Timing of feed motion

Operating sequence:
When lihe rising needle has left the fabric, the feed dog moves up above the needle
The risen feed dog pushes the fabric to the
take-up lever is in its highest positi o n (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
movement).
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
Whenever the stepping motor changes the sewing direction from forward to reverse sewing, the feed
dog must be positioned 0.3 mm below the needle plate surface on its way downwards.
Requirement:
When the needle bar has moved
two
the pins of pin gauge 63-114 690-09 simultaneously in the holes of the feeding eccentric and the
stud (fig. 3).
Check:
e Remove the needle.
Turn the handwheel to set the needle bar at
•
• Set the spacer (63-1 02 600-18) onto the needle bar and push
e Push the needle-rise clamp (00-870 137-01) on the needle bar and tighten it lightly.
e Push the 2 mm feeler gauge {00-870 136-01) with its cutout on the needle bar above
the neeclle-rise clamp.
e Loosen the needle-rise clamp and push the 2 mm feeler gauge up against the spacer.
• Tighten the milled screw of the needle-r i s e clamp
• Turn the handwheel to and fro a little.
If
there is play at the feeler gauge, repeat this procedure.
•
e Remove the 2 mm feeler gauge.
e Turn the handwheel in sewing direction until the needle-rise clamp Is up against the spacer
(fig. 3b).
e Tilt the machine over backwards.
e Hold the handwheel in this position while at the same time inserting the pin gauge in the holes
of feeding eccentric 20 and stud
Timing:
• If
the adjustment is not correct. remove
e Loosen the three screws 23 in the lower toothed-belt sprocket
Re-fit the needle-rise clamp and repeat
•
moved
has
upwards by 2 mm and the clamp is in contact with the spacer (flg. 3b).
m
u the long drive shaft 2 1 in sewing direction until
• T
both
holes (fig. 3).
e Insert the pin gauge and tighten screw 23.
Cross -c heck:
• Remove the pin gauge.
e Tighten all three screws 23 very firmly.
e Check again wi t h the needle-rise gauge and the pin gauge as described under .Check".
10
Shortly before the end of the feeding
rear.
to
mm up from its lowest position (b.d.c.),
2
its lowest position.
(fig.
22
(fig. 3).
the needle-rise clamp.
the procedure as described in .Check" until the needle bar
it
its ba.sic posi t i on.
it
must be possible to insert
it
up against the needle bar frame.
3a).
is possible to Insert the pin gauge in
plate.
the
motion,