Dürkopp Adler 271 Instruction Manual page 44

Cl. 274-140342 Like the basic type, but with needle transport,
intermittent
roller upper feed, with electro-magnetic automatic
locking and electro-magnetic sewing foot lift.
Standard equipment with keys for locking within
the seam progression, for needle high-low and/or
single stitch, tack call up or
suppression and lifting or lowering of the upper
feed roller.
This sub-class requires a pneumatic connection.
With sewing machine drive Efka DC1500.
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