Pin Breakage
CAUSES: High static or impact loads
which cause crack to start at outer surface
(usually at pin wear step) and moves
through entire pin at a fast rate.
Pin cracking and breaking is less severe
with Sealed and Lubricated Track during
absence of internal wear. However, it may
be more serious once lubricant is lost and
internal wear is present due to faster rate
of internal wear and loss of pin strength
due to reservoir hole.
ACCELERATORS: Horsepower, weight
and speed of machine. Impact and terrain
conditions. Amount of internal wear that
reduces pin diameter. Tight track, too-
wide shoe, worn rear rollers and severe
packing loads caused by rocks between
bushing and sprocket are main control-
lable variables.
EFFECT: Immediate track separation.
Severe damage to other components.
REMEDIES: Eliminate or reduce control-
lable accelerator variables, particularly rocks
which are getting into spaces between
sprocket and bushings.
Sealed Track Pins
& Bushing Turn and
Replacement Guidelines
The following guidelines should be used
in determining if and when Sealed Track
pins and bushings should be turned and/or
replaced. The general guidelines discussed
in the section entitled “Track Manage-
ment” should be understood and practiced
before applying these specifics.
1. If a Sealed Track pin and bushing turn
and/or replacement is required to help
utilize total track link life it should be
done on or before either the internal
wear or external bushing service points
(100 percent worn) are reached, which-
ever comes first.
2. If a pin and bushing replacement is
required to help utilize the projected
total potential link life following the
turn of a previous set of pins and bush-
ings, it should also be done on or before
either the internal wear exceeds the ser-
vice point (100 percent worn) or the
external bushing surface is run to destruc-
tion (120 percent worn), regardless of
which occurs first.
3. When in doubt, turn early for best after
turn and after replacement wear and
structural life performance contributing
to overall best total track life and parts
reusability.
Do not use these criteria to determine if
and when to turn as they involve unreli-
able measurement techniques:
1. Sprocket wear lines or general sprocket
tooth wear condition.
2. Extent of idler adjustment used to remove
slack is determined by pitch extension
from internal wear.
3. Waiting until other components (such
as shoes) are ready for maintenance or
service based on previous experience of
phasing work at the same time.
Remember, if pins and bushings are
run to destruction internally prior to
replacement, then the replacement set
may give as little as 80 percent life of
the original set.
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SEALED TRACK PINS & BUSHINGS
General Information