8.
Construction
and
operation
of
motor
lever switch
(Full
details are given in
the
Instruction
Book
of
Hitachi and National
Stop
Motor, so it is
lightly
treated
here)
1)
In
case
of
Hitachi
mighty
stop
motor
Thread
trimming
stroke
adjusting screw
Safety
lever
Safety solenoid
L.SW
Motor
lever
returning
spring
Thread
trimming
T.sw spring
- 5
Step-in force
adjusting screw
speed
spring
Main
lever
/^
Thread
trimming
Auxiliarv'lever
Auxiliary
lever
switch
Auxiliary
lever
force
adjusting
nut
adjusting
screw
stopper
screw
Basically,
this
lever
switch
needs
no
adjustment.
However,
as
there
are
2-3
places
which
can
be
adjusted
so
adjust
them
in
accordance
with
the
following
instructions.
Even if
the
pedal
is
stepped-in
to
the
thread
trimming
position,
the
needle
can
not
rise
completely
up
due
to
the
insufficient
torque
of
the
motor
(when
it
stops
during
thread
trimming
operation)
or
when
the
machine
does
not
stop
at the designated position,
tighten
the
step-in force
adjusting
screw. Please
note
that
when
this screw is
tightened,
the
pedal
pressure
gets
big
when
this
is
stepped-in
to
the
high speed, so
tighten
lightly as
long
as
there
is no
abnormalcy
in
thread
trimming
or
machine
stopping
operations.
When
the
step-in
returning
amount
at
thread
trimming
is to be
changed,
the
machine
is so
adjusted
for
easy
step-in
returning
amount
operation.
However,
when
the
machine
is
to
be
operated
for
the
first time, sometimes it is easier to operate if the step-in returning
amount
at thread trimming
time
is increased. In
such
a case,
return
the
thread
trimming
stroke
adjusting
screw
within
the
area
of
l~3mm(3/64~l/8"). At the sametime, return the thread
trimming
switchadjusting
screw
and adjust
so that
T.SW
will
activate at lmm(3/64") before the auxiliary lever hits the thread trimmingstroke
adjusting screw and stops.
After
the
adjustment,
tightly
tighten
the
locknut.
Do
not
adjust
the
low speed step-in force adjusting screw or auxiliary lever
stopper
spring.
This lever
switch
is so assembled
that
even if
the
clutch
lining
of
the
motor
is
worn
out,
it is
not
necessary
to
readjust
the
position
of
the
auxiliary lever
stopper.
When
the
low speed step-in force
adjusting
nut
is screwed in and
the
pressure
of
the
low speed sewing pedal is
strenthened,
the
safety
device activates and when the auxiliary lever hits the auxiliary lever
stopper
and stops, the main
lever also moves to a certain degree with the force of the low speed spring.
Due to this
action,
there
is a danger
of
the machine to
keep
on
running
at high
speed
and
the
possibility
of
the
safety
device
unable
to
perform
its role.
After
the machine is used for 1-2 days,
the
operator
will get used to the machine, so do
not
try
to readjust the step-in force at
the
time
of
low
speed
sewing.
If
the
machine can
not
run at high speed even if the
safety
device is
not
working, it is because
the
clutch
lining is worn
out.
Exchange the lining with a new lining. If the position of
the
auxiliary
lever
stopper
is
not
changed at
the
time
of
the
new lining, it means the
phenomenon
is
due
to the
abrasion
of
the
clutch
lining. It is
better
not to readjust the auxiliary lever
stopper
nut.
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