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REPLACING SAFETY DISCS AND WASHERS ON INFLATION VALVES | Up
Aircrew Survival Equipmentman 1 & C - Aviation theories and other practices | Next
PREVENTIVE MAINTENANCE |
S E W I NG
CHAPTER 4
MACHINE REPAIR
The Aircrew Survival Equipmentman (PR) is
called upon to perform an enormous amount of
repair work on parachutes and survival equipment
in all types of maintenance activities. Although
lower rated personnel perform much of this work,
the task of maintaining the sewing machines in
top running condition falls to the senior PRs.
Qualified sewing machine operators may assist in
this work under supervision; however, determin-
ing the causes of malfunctions, making major
adjustments, and replacing parts are the respon-
sibilities of the first class and chief petty officer.
This chapter explains the rotory-hook (111 W
155) sewing machine and the oscillating-shuttle
(31-15) sewing machine. We gave you an overview
of these two types of sewing machines in chapter
3 of the Aircrew Survival Equipmentman 3 & 2,
volume 1; however, as a senior PR, you need more
specific information on the basic structure of these
two sewing machines. With the information
available, you can repair any of these types of
machines the Navy uses. We know it is very
difficult to find information on sewing machine
repair; therefore, you should use this chapter as
a reference when working on the alternating-
presser-foot sewing machine and the simple
oscillating-shuttle sewing machine.
Your shop may have the Consew Model 225,
the Juki LU-562, or the Singer Model 111 W 155
sewing machine. These three sewing machines are
essentially identical, and all specifications and
instructions are the same for all three sewing
machines. For simplicity we will use the Singer
111 W 155 as a model for all three sewing
machines.
The oscillating-shuttle, Singer 31-15, sewing
machine is representative of the second type of
sewing machine used by the Navy. The descriptive
term oscillating shuttle refers to the action
of the sewing hook (the way it makes a stitch
in unison with the needle). The 31-15 is used
for sewing lightweight fabrics and is ideally
suited for use in the maintenance of aviation
survival equipment. Although the physical size
of other oscillating-shuttle sewing machines may
be quite different from the 31-15, such as the large
C l a s s 7 m a c h i n e s,
t h e i r o p e r a t i o n a n d
maintenance are very similar.
111 W 155 SEWING MACHINE
The 111 W 155 sewing machine is a single-
needle, compound-feed sewing machine with
alternating presser feet. This sewing machine
makes the standard US 301 lockstitch and sews
medium-heavy fabrics. It is equipped with a
vertical-axis rotating hook. This sewing machine
is classified as a rotory-type sewing machine and
is also equipped with two presser feet; one is a
vibrating presser foot, and the other one is a
lifting presser foot. The front (vibrating) presser
foot, the needle, and the feed dogs move in
unison. Together they move the cloth away from
the operator with each completed stitch. The rear
(lifting) presser foot holds the fabric in place while
the vibrating presser foot rises and moves forward
to start the feeding action for another stitch. This
sewing machine is capable of operating at a speed
of 3500 stitches per minute (SPM). The stitch
regulator provides a range of 3 1/2 to 32 stitches
per inch (SPI).
The 111 W 155 is the same sewing machine
in most ways as the 111 W 151, except for its
alternating presser feet, which give the 111
W 155 a more positive feeding action. The
111 W 155 also has a longer stitch length
(3 1/2 SPI instead of 5 SPI) and a higher
maximum presser-foot lift (one-half inch instead
of three-eighths inch). The 111 W 155 is an ideal
sewing machine to use on medium-heavy fabrics
such as vinyl and canvas.
This RTM will also include disassembly and
assembly of the 111 W 155 sewing machine. To
simplify minor repairs to this sewing machine and
the 31-15 sewing machine, we have placed our
discussion of disassembly and assembly to the rear
of the chapter.
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