Self-Locking Fasteners; Washers; Cotter Pins; Circlips - Polaris 1999 Sportsman 400 Service Manual

8
MACHINE SCREWS
CHAPTER ON E
Hex
Flat
Oval
Fillister
Round
Se lf-Locking Fasteners
Severa l types of bolts, sc rews an d nuts incorpo-
rate a system that develops interference between the
bo lt, screw, and nut or lapped hole threads. Interfer-
ence is achieved in various ways: by distort ing
threads, coating threads with dry adhesive or nylon,
distorting the top of an all-metal nut, using a nylon
insert in the center or at the top of
a
nut.
Self-locking fa sten ers off er grea ter ho ldin g
strength and
better
vibrati on resistance. Th e
se lf-locking
fasteners
used on the Po laris ATV
can-
not be reused.
Others, like the nylon insert
nut ,
form
an
initial lock ing
condition
when
L ite nut is first in-
sta lled; the nylon forms c lose ly
10
the bolt thread
pattern, thus reducing any tendency for the nut to
loosen . A lways disca rd and replace selfClock ing
fasteners after removal.
Was hers
Th ere arc two basic type s of wa shers: Ilat was h-
ers and lockwas hers. Flat washers are simple discs
with a hole
to fit a screw or
bolt.
Lockwashers
are
designed to prevent a fastener fro m working loose
due to vibration. expansion and contraction.
\Vashers can be used in the fo llow ing functions:
I.
As spacers.
2. To prevent galling or damage of the equipment
by the fastener.
3. To help distribute fastener load during tightening.
4 . As seals.
Note that flat washers arc often used between a
lockwasher and a fastener to provide a smooth bear-
ing surface. This a llows the fastener
to
be turned
eas ily with a tool.
NOTE
As much care should be g iven to the
se lection and purchas e of washers as
that gi ven to bolts, nuts and other/as-
teners. Beware
of
washe rs that are
made
0/
thin
and
weak
materials.
These will deform and crush tile firs t
lime they are used in a high-to rque
application.
Cotte r Pins
In
certain
applications. a fastener must be
secured
so it cannot possibly loosen. The rear hub on an
ATV
is one of'
these
applications. Forthis purpose, a
cotterpin and
slo
tted orcastellated
nul
is often used.
To use a cotter pin. first make sure the pin fits
snugly,
but
not too light. Th en align the slot in the
fastener wi th thc hole in the bah or axlc.
Insert
the
cotter
pin thro ugh the nul and bolt or
axle and bend the ends over to secure the cotter pin
tightly. If the holes do not align. tighten the nut j ust
enough to obtain the proper alignment. Unless spe-
cifically instructed to do so. never loosen the fas-
tcner
10
a lign thc slo t
and
the hole. Because the
cotter pin is weakened after installation and
re-
moval, never reuse a cott
er
pin. Cotter pins are
available in several styles. lengths
and
diameters .
Measur e the cott er pin length fro m the bottom of its
head to the lip of thc sho rtes t pron g.
C irclips
Cir clips can be internal or external in design.
They are used
to
retain items on shafts (external
type ) o r wit hin lub es (interna l type). In so me app li-
cations. circlips o f varying thicknesses are used to
control the end play of assemblies. These are often