Beisler 1225-5 - Manual (Page 14)

4.4 Setting the differential feed
By the differentials the behaviour of the feed-dogs can be altered.
Permanent differential
The left lever 2 (seen from behind) influences the permanent
differential, which is active during the whole sewing process.
The setting range is between -10 and + 6.
The higher the setting (positive numbers),the more the material is
gathered. The lower the setting (negative numbers), the more the
material is stretched.
Additional differential
The right lever 1 influences the additional differential, which is
programmable in the control and provides additional width in certain
seam sections only.
The setting range is between 0 and + 16.
The higher the positive number, the more additional lining is gathered
at the programmed positions.
10
2 1