2)
How
to
adjust
the
maximum
sewing
speed
(for
the
4,000
s.p.m.
type
PSC
box)
The
maximum
sewing
speedisadjusted in the twodifferent
ways,i.e. by using400 s.p.m.-stepspeed control knob
( @ in
Fig.
3-12)
which
is
designed
to
change
onlythe
maximum
sewing
speedwithout
changing
the relationship
between the rotational
speed
of the
sewing
machine
andthe
pedal
stroke(hereinafter
called
"start-up")or by
using
the
max.sewingspeed control knob ( O in Fig.3-12) whichis
designed
to
change
the max.
sewing
speed
by
retarding
the
start-up.
The former method is equivalentto the conventionalmethod
to adjustthe
max.
sewing
speed
by
replacing
pulleys,
andthe
latter
method
is
equivalent
to the
adjustment
using
the
max.
sewing speed control knob.
The
actual
max.
sewing
speed
will
bethe
lower
one
specified
usingeither O or © .
i ^
.2
ai
s I
IT S
Fig.
3-12
Direction
toward
smaller
scale
value
Direction
toward
larger scale values
Fig.
3-13
w
Pedal
stroke
Table
3-2
(1) 400 s.p.m.-stepspeed control knob
400 s.p.m.-stepspeed control knob can be set to 16
different steps from 1 to 16 in 400
s.pm.
steps.
The sewingspeed, therefore, can be adjusted to
400
through 4,000 s.p.m. with ease.
This method of limitting the maximum sewing speed
increases/decreasesonly the maximum sewingspeed
without changingthe start-up as shown by the
arrows in Fig. 3-13. The desired sewing speed can
be easily reached even when the max. sewing speed
is
set
to
low.
The relationshipbetween the scaleof the switch and
the sewingspeed is asshownin Table 3-2. The max.
sewingspeed changes after thread trimming or
re-tuming ON the power to the machine. Conse
quently, the changingof the switch duringsewing
will
not
be effective until the machine performs
a thread trimming.
Scale
value
1 2 3
4
5
6 7
8
9
10~16
Max.
sewing
speed(s.p.m.)
400
800
1200
1600
2000
2400
2800
3200
3600
4000
S a>
Clockwise
Ol u>
Pedal
stroke
Fig.
3-14
7
^
^Counterclockwise
O ^ \ /
(2) Max. sewingspeed control knob
The
function
of
this
dial
knob
is as
same
as
that
of
the conventional max. speed control knob. Turn
the
dial
knob
clockwise
to
increase
the
rotational
speed of the sewing machine, or counterclockwise
to decrease it. The range
of
adjustable speed is
from 200 to 4,000 s.p.m. In this method, the
max. sewing speed is changed with the start-up
retarded,
which
makes this
method
different
from
the one described in (1).
The max.
sewing
isdecreased in the orderas O to
0 to © by turning the dial knob counterclock
wise.
This dial knob is designed
to
use the pedal stroke
to the full until the specified max. sewing speed is
reached. On the contrary, speed acceleration on
the way is sluggish.
It is
advisable
to adjustthe start-upby appropriatelycombining methods(1) and (2) by meansof knobs O and ©
accordingto the sewingprocessor to the operator's convenience.
-
26
-