guide (10), which is located on the needle clamp.
The needle is now threaded from left to right
through the eye of the needle (11). After the needle
is threaded as shown in figure 9-19, pass the
thread down through the hole in the lifting presser
foot (12). Draw about 4 inches of thread through
the hole in the lifting presser foot with which to
begin sewing.
Notice that the lubricating cup has been
bypassed. No lubricant is used on the threads and
cords used in the manufacture or repair of
parachutes.
Removing the Bobbin
Turn the balance wheel forward to bring the
needle bar and thread take-up lever to its lowest
position. With the aid of the shuttle opening tool
or a small screwdriver, insert the blade end in the
slot in the spring latch beneath the shuttle cylinder
(fig. 9-20). Press the latch away from the cylinder
and it will swing out. The bobbin will then slide
out of the shuttle cylinder.
Winding the Bobbin
Place the bobbin on the bobbin winder spindle
and push it up closely against the shoulder. The
small pin in the shoulder must enter the slot in
the bobbin.
Pass the thread from the thread stand through
the hole in the left side of the bobbin from the
inside. Push the bobbin winder pulley up against
the balance wheel, and place the bobbin winder
Figure 9-20.—Removing the bobbin
cylinder.
239.277
from the shuttle
239.278
Figure 9-21.—Replacing the bobbin.
latch in position. Raise the presser foot and start
the machine. The end of the thread should be held
until a few turns are wound on the bobbin to
prevent slipping. When sufficient thread has been
wound on the bobbin, the bobbin winder will stop
automatically.
Replacing the Bobbin and
Threading the Shuttle
Take the bobbin between the thumb and
forefinger of the left hand, as shown in figure
9-21. The free end of the thread should be drawn
off from the underside toward the right. Place the
bobbin in the shuttle cylinder as far as it will go.
Draw the thread into the slot in the cylinder and
under the tension spring into the delivery eye.
Push the shuttle cylinder in until it is locked by
the spring latch. There should be about 3 inches
of thread hanging free from the shuttle with which
to begin sewing.
Regulating the Tension
The tension on the needle thread is regulated
by the thumb nut at the front of the thread
retainer disks. The tension on the thread retainer
disks should be just enough to cause the tension
wheel to turn when the thread is taken from the
spool.
The tension on the bobbin thread is regulated
by the small screw that holds the tension spring
to the shuttle cylinder. To increase the tension,
9-16
