28.
Regulating
the
Pressure
on
the
Material
The
amount
of
pressure
to
be
exerted
by
the
work
clomp
should
be
set
in
occordcnce
with
the
material
to
be
sewn.
By
tightening
the
presser
bar
thumb
sorew
on
top
of
the machine
arm,
the
pressure
can
be
regulated
in
such a
manner
as
to
ensure
perfect
feeding
of the
material
and
to
prevent
fabric
pucker
as
well
as
poor
buttonhole
seams.
29.
Changing
the
Butter
Spring
To
absorb
the
momentum
of
the
machine
ond
reduce
the
impact
on
the
stop
motion, a
powerful
buffer
spring is
provided
in the
rear
driving pulley
of
the
machine.
The
machine
is
blocked
when
the
take-up
has
almost
reached
its
highest
position and the needle
bar
has
descended
about
.118" (3.0 mm) from the
highest
point
of
its
stroke.
The buffer spring is
exposed
to excessive stress
and
may
slacken or
break
after
some
time
as
a
result
of
fair
wear
and
tear.
A
broken
or
worn
spring
causes
irregular stopping of the machine, leaving the needle
bar
and
Ihc
take-up
in
varying
positions. Thus it
may
occur
that
the
needle
bar
is so
low
when
the machine
stops
that
the
needle
is
damaged
or
broken
by the
needle
thread
trimmer.
In
order
to
replace
the
broken
buffer
spring, loosen
both
tension springs
Dj
and
Ei (Photo 32),
remove
screws
Ji
and
e,,
pull
out
hinge
pin F,,
end
take
off
the hinged
stop
motion
and
brake
lever
assembly.
After
removing the four
set
screws
f,,
f2,,
fj and (Photo 32),
take
off
cap
ring G,
and
stop
cam H,
and
remove
the
broken
buffer
spring.
The new spring is inserted
between
the
two
spring
rests
Kt (Photo 33)
and
compressed
sufficiently to permit inserting the
Novotex
segment Jj.
To
facilitate
exchanging the
buffer
spring, it is
recommended
to use a
special wrench which we will furnish on
order,
together with the new
buffer
spring. As shown in
photo
33,
insert
a punch info hole L,
located
on
the rim of the
rear
driving pulley
and
turn Ihe pulley until punch M,
resl^
against
the bearing
bracket
0|.
Then slide the loose spring
rest
on
ihe
stud of the wrench
and
push the wrench on the
top
shaft
hub. Take the
wrench
in
your
left
hand
and
press
it
straight
down,
thus compressir^g
the buffer spring, until the Novotex
segment
can be inserted.
Make
sure
that
the straight side of the spring
rest
faces
the
Novotex
segment. Replace
land
screw
on
stop
cam
and
cap
ring
and
mount the hinged
stop
motion
and
brake
lever
assembly.
37
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