DURKOPP ADLER 669 ECO Operating Instructions Manual page 41

Operation
Operating Instructions 669 - 00.0 - 08/2019
To set the sewing foot stroke:
1. Turn adjusting wheel (1) and (2) (from 1 to 9).
• 1: minimal sewing foot stroke
• 9: maximum sewing foot stroke
Automatic stitch rate limit
Machines without a thread trimmer
The speed is not verified on these machines.
Machines with a thread trimmer
The sewing-foot stroke and stitch count are interdependent. A
potentiometer is connected mechanically with the adjusting wheel.
The control unit detects what foot-stroke has been set by means
of this potentiometer and restricts the speed of rotation accor-
dingly.
Machines with electro-pneumatic rapid stroke adjustment
When processing thick sections of material or when sewing over
transversal seams, the higher sewing-foot stroke (adjusting
wheel (1)) can be activated while sewing by means of the knee
switch (3) (under the table plate).
A potentiometer is used here just as in the machines with thread
trimmers.
Operating mode for the rapid stroke adjustment
The activation time for the maximum sewing-foot stroke depends
on which operating mode is set. You can select between three
different operating modes.
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