To Set Check Spring Tension - Singer 491D Service Manual

SETTING:
Loosen screw E, Fig. 3. Turn stud F,
Fig. 3 (at the same time turning entire ten-
sion assembly) either over toward left to
lower check spring and decrease its movement,
or over toward right to raise check spring
and increase its movement. Securely tighten
set screw E.
NOTE: Under certain conditions of
tacking, it may be necessary to set the
check spring higher than it is otherwise
normally set.
CAUTION: Check spring height setting
must be checked each time a different foot
is applied to machine.
PREPARATION:
Thread the machine, securely tighten
set screw E, Fig. 4. Make certain thumb nut
is on stud F, fig. 4.
CHECK:
Tension on check spring D, Fig. 4,
should be sufficient to ensure action at top
speed; but still light enough to permit it-
self to be drawn all the way down (as take-
up lever approaches height of stroke) before
any thread is drawn through the tension
discs.
SETTING:
Using a large screwdriver in slot of
stud F, turn stud either over toward left to
decrease tension or over to right to in-
crease it, as shown.
NOTE: The tension on the check spring may require different settings
depending upon the size of thread used. Heavier thread requires more tension
to ensure correct thread control.

TO SET CHECK SPRING TENSION

- 3 -
D
LOWER
F
D
MORE
TENSION
LESS
TENSION
HIGHER
LOOSEN
E
Fig. 3
TIGHTEN
E
F
Fig. 4