Adjustment Of Thread Check Spring Stroke - Pfaff expression 2014 Service Manual

19. Adjustment of thread check spring stroke

The tread check spring prevents the descending needle from piercing the slack needle thread. The needle
thread is slackened by the descending take-up lever.
Requirement:
Thread check spring 144 must keep the needle thread taut at least until the needle point enters the fabric
(Fig. 51a).The thread check spring must release the needle thread as soon as the lower edge of the
needle eye enters the fabric.
Check:
Select stitch pattern "for" straight stitch.
Set the stitch length at "6.0".
Place two pieces of fabric under the sewing foot.
Sew a few of stitches.
Turn the handwheel and determine the end of the tread check spring stoke. Correct
slackening of the needle thread takes place when it enters the needle eye not tautly but in a
loose curve.
Adjustment:
Loosen screw 142.
Turn thread check spring stop sleeve 143 until thread check
spring 144 is in the correct position.
Tighten screw 142.
Cross-check:
Sew a few stitches and check as described under "Check".
48