There are two types of slide fasteners
separating and nonseparating. A nonseparating,
type A, slide fastener is used where only a small
area needs to be opened; for example, the opening
in a parachute bag. A separating slide fastener,
type B, is used in areas where it is necessary to
spread the opening for easy access, such as on a
jacket or the legs and waist of an anti-g coverall.
To determine the size or service weight of a
slide fastener to be installed on a fabric assembly,
consider the weight of the material and the stress
that will be applied. The size range and services
of slide fasteners are as follows:
1. Size 0 - light service
2. Size 1 - light to medium service
3. Size 2- medium service
4. Size 3- medium to heavy service
5. Size 4- heavy service
Materials used inslide fastener construction
vary from plastic and nylon to cotton, rubber, and
metal. There are two common grades of slide
fastener chains. Grade I is of brass construction
and Grade II is made of other metal alloys or
In most instances, however, you will be
concerned with fasteners that have been
constructed from cotton fabric and metal parts.
A closely woven cotton fabric is commonly
used for the tape of a slide fastener; match the
color of this tape to the main fabric color when
installing a slide fastener.
On certain items of survival equipment using
slide fasteners, it is mandatory that the slider
remain stationary where it is positioned on the
chain. An accidental opening in flight of an
equipment container or item of flight clothing
could cause a lot of trouble for the aircrewman.
Unintentional opening of a slide fastener that
requires positive security is prevented by using a
locking style L slider.
Illustrated in figure 10-20 are two common
types of locking style L sliders: the pin type and
the cam type. The pin type is designed to lock
when the pull tab is pressed flat onto the chain,
thereby inserting its pin between two teeth on one
side of the chain.
The cam type is also designed to lock when
the pull tab is pressed flat onto the chain, thereby
causing friction between the chain and the cam.
This action prevents any movement of the slider.
Slide fasteners installed where the movement
of the slider is not critical may be equipped with
a style S, standard nonlocking slider. The style
S slider is normally used on slide fasteners where
accidental openings do not create a problem.
The length of a slide fastener is determined
by the amount of closure required. When ordering
slide fasteners from class 5325 of the Federal
Stock Catalog, you need to refer to the dimension
column, which lists both the length of the chain
and the width of the tape. The size of a slide
fastener is referred to as its service weight.
Activities should specify the brand of chain
for which stops and sliders are required (Talon,
Crown, or any other make).
Slide fasteners in stock are supplied in the
nearest length ordered. When received, you can
cut the chain to the desired length; stops can be
salvaged and reused on the cut chain.
SEAMS AND KNOTS
A variety of seams and knots are presented
in the following text.
This is the age of great technological
advancements and man has come to rely heavily
on the conveniences that technology provides. As
you know, almost everything you do involves the
use of a machine. From the housewife with her
automatic dishwasher and the computer that pays
you regularly twice each month to the sewing
machine you use to repair articles made from
fabric, technology is involved. Very few people
in our society have the opportunity to use hand
skills; therefore, they search for hobbies, such as
model aircraft building, carpentry, and leather
crafts to satisfy this desire.
You are fortunate because your job involves
using both hand and machine skills. Very few
people get the opportunity to work with raw and
finished materials and have creating, fabricating,
and repairing as part of their job. In your
particular situation, not only do you use your
hands for tying knots and packing life rafts, but
you also use your hands to take the place of a
sewing machine. By now you have seen that
sewing is perhaps the most useful skill the
fabrication and parachute specialist should
develop. Few fabric maintenance jobs are
performed without some kind of sewing.
Although, from your experience, you know that
most sewing is done with a machine; you also
know there are occasions when machine sewing