Bushing Loose in Links
See “Sealed and Lubricated Track Bush-
ing Structural Problems.”
Sealed Track Pitch
Internal Wear
Measurement Technique
Sealed Track internal wear is measured by
determining the pitch extended length over
four adjacent sections with a tape measure
calibrated in 0.02" (0.5 mm) increments.
Except on 5230, measure only 3 adjacent sections.
The track and tape must be stretched tight
and straight to obtain an accurate measure-
ment. The calibrated side of the tape should
be located along an imaginary line which
connects the pin centers. The reading
should be made from one side of a pin to
the same side of the fifth pin away (which
includes 4 track sections).
The hook on the 0" (0 mm) end of the tape
should not be used and the mark at an
even increment of inches or centimeter
should be placed at the 5th pin leaving the
end of the tape free to measure the frac-
tional part of the total length (see diagram
above.) This measurement should be taken
at least 3 sections away from one-piece
type master link joints and should be
repeated at least twice over different
sections of the track on both sides of the
machine. This measurement can be used
directly to find percent worn in the charts.
Wear Limit and Percent Worn Chart
The wear limits and wear charts for internal
wear include only the 0.12" (3.1 mm) lesser
allowable wear.
Since “destruction point,” as related to
internal wear, actually results in external
bushing break-through (which is also a
result of external wear) both internal and
external worn percent must be known to
make an accurate projection of the destruc-
tion point.
Dealers and users who, because of very
low impact conditions, can successfully
extend the allowable internal wear past
100 percent may establish their own
criteria for allowable internal wear. It
should be remembered that the internal
wear limits and percent worn charts are
based on the following criteria:
1. Total pin life before plus after-turn pin
and bushing internal wear life.
2. Total wear life potential and rebuild-
ability of all components with wear
lives which are effected directly or
indirectly by internal wear and result-
ing snakiness.
3. The direct contributing effect of internal
wear to external bushing wear-rate and
loss of bushing wall strength as to
prevent bushing cracking.
Life of pins and bushings after turn should
be about 80 percent of life before turn.
Life after replacement about 100 percent.
48
SEALED TRACK PINS & BUSHINGS
General Information