the component parts. The primary feature of each
component is explained in the following text:
Lifting Presser Bar Tension Regulating
Screw. Regulates the pressure on the alternating
Feed Indicating Disc. Indicates the number
of stitches per inch which are being made by the
Balance Wheel. Provides a connection
between the driving unit and the sewing machine
Arm-and-Hook Driving Shaft Connection
Belt. Connects the upper arm shaft with the hook
Feed Dog. Feeds the material from the
Rotary Hook Assembly. Contains the
mechanism that forms the lockstitch by using the
needle and bobbin threads.
Bobbin. Contains the lower thread used in
forming the lockstitch.
Bobbin Case Retainer Hook Gib. Holds
the bobbin case in the bobbin race.
Needle-deflecting Hook Washer. Deflects
the needle so the rotary hook will not strike the
Throat Plate. Surrounds the feed dog and
keeps the material from slipping after the feed dog
has been adjusted to the proper height.
Bed Slides. Covers the feed eccentric and
hook assembly on each side of the throat
Feed Indicator Plunger. Used in
connection with the feed indicator to regulate the
number of stitches per inch desired.
Safety-clutch Lock Stud. Re-engages the
needle with the hook driving assembly after
clearing a thread jam.
Bobbin Case Opener. Prevents thread
from jamming underneath the throat plate on the
bobbin case base.
Figure 9-25A.Class 111 sewing machine, side view.
Rotary Hook Saddle Complete. The rotary
hook is operated by the spiral driving pinion gear,
which, in turn, is operated by the hook driving
gear located on the hook driving shaft.
Rotary Hook and Connection Belt Timing
Plate and Arrows. Used to time the arm shaft with
the hook driving shaft.
The following parts are shown in the side view
of the Class 111 sewing machine (figures 9-25A
and 9-25 B).
Thread Take-up Lever. Pulls the needle
thread against the tension disc after the lockstitch
is formed at the rotary hook and pulls suffi-
cient thread from the spool to make the next
Vibrating Presser Bar Tension Regulating
Screw. Regulates the pressure on the presser foot.
Only sufficient pressure to
securely is needed.
hold the material
Face Plate. Covers
mechanism of the two pressel
and protects the
feet and needle bar.