Duerkopp Adler 550-867 Service Instructions Manual page 92

"Thread tension"
This function is for the setting of the thread tension in consideration of
the preset tolerance limits, the sewing speed, the lift stroke as well as
the stitch length and for the checking of the thread tension after a
Teach-in process in connection with a ETT.
See chapter 6.6 Tolerance range of the thread tension.
"Thread tens.file"
After pressing this button a thread tension file can be loaded.
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