Self-Locking Fasteners - Arctic Cat Cougar Service Manual

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bolts are described by the diameter and pitch (the
distance between each thread).
Nuts
Nuts are manufactured in a variety of types
and sizes. Most are hexagonal (six-sided) and fit
on bolts, screws and studs with the same diame-
ter and pitch.
Figure 20 shows several types of nuts. The
common nut is generally used with a lockwasher.
A self-locking nut usually has a nylon insert that
prevents the nut from loosening and no lock-
washer is required. Wing nuts are designed for
fast removal by hand and are used for conven-
ience in noncritical locations.
To indicate the size of a metric nut, manufac-
turers specify the diameter of the opening and
the thread pitch. This is similar to bolt specifica-
tions, but without the length dimension. The
CHAPTER ONE
measurement across two flats on the nut indi-
cates the proper wrench size to be used.
Self-Locking Fasteners
Several types of bolts, screws and nuts incor-
porate a system that develops an interference
between the bolt, screw, nut or tapped hole
threads. Interference is achieved in one of the
following ways: by distorting threads, coating
threads with dry adhesive or nylon, distorting the
top of an all-metal nut or using a nylon insert in
the center or at the top of a nut.
Self-locking fasteners offer greater holding
strength and better vibration resistance. Some
self-locking fasteners can be reused if they are in
good condition. Others, like the nylon insert nut,
form an initial locking condition when the nut is
first installed. The nylon forms closely to the bolt
thread pattern, thus reducing any tendency for
the nut to loosen. When the nut is removed, the
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MACHINE SCREWS
Hex Flat Oval Fillister Round
Common nut
Self-locking nut
Folding
Plain
Wing nut
Internal tooth
External tooth