Manual Trimming Test - Pfaff 900/56 Service Manual

Adjustment
19

Manual trimming test

26
To ensure that the thread will be properly caught on two needle machines and on
machines with the hook to the left of the needle the feed and lifting motion of
the feed mechanism should be set at 0.6 mm before needle bar b.d.c.
-900/61
2
2 mm
-900/56
2
Thread machine, place fabric under presser foot and turn balance wheel to sew a few
stitches.
Turn balance wheel in feeding direction until needle bar is 10 mm before b.d.c.
Operate engaging lever 1.
Continue turning balance wheel slowly and watch catcher 2.
During its forward movement catcher 2 must touch bobbin thread lightly, however,
without pushing it. If necessary, re-adjust catcher height (chap. 12).
When catcher 2 is at front point of reversal bobbin thread must be a positioned behind
end of catcher by at least 2 mm (see Figs. at upper or lower left). If necessary, change
setting of catcher stroke (chap. 10) (clearance between connecting link and centre of
catcher driving shaft). Displacing connecting link in direction of catcher driving shaft
increases catcher stroke, displacing it in opposite direction, decreases stroke. Afterwards
check adjustment (chap. 13) (thread catcher rest position).
After trimming action both needle and bobbin thread must be a properly trimmed and
bobbin thread trapped. Re-adjust height of bobbin in thread clamp spring, if necessary
(chap. 16).
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