Link Rail Wear
Measurement Technique
Track links may be measured by the depth
gauge or by the ultrasonic wear indicator.
The depth gauge measures link height
from the rail surface to the track shoe. The
correct location for track link measure-
ment is outside of the links at the end of
the track pin. Position the depth gauge as
close to the end of the pin as possible,
making sure links and shoe surface are
clean. Ensure the gauge is flat against the
link rails and perpendicular to the shoe
surface. Measurement should be made to
the closest 0.01" or 0.25 mm.
The ultrasonic wear indicator measures the
distance from the rail surface to the bushing
bore. Place the probe on the link above the
centerline of the bushing and slide the
probe along the tread surface to get the
smallest reading.
Wear Limits
Link wear limits are determined by setting
the allowable wear equal to some fraction
of the clearance between the link and the
roller. On some machines this clearance is
between the link pin boss and the roller
flange. On other machines the clearance is
between the bushing and the inner flanges
of a double flange roller.
On a 100 percent worn link matched
together with a 100 percent worn roller,
the roller flanges are in contact with either
the link pin bosses or the bushing. As wear
proceeds past 100 percent, wear on the
link pin boss reduces pin retention, wear
on the bushings may cause cracking, and
wear on the roller flanges reduces track
guiding and roller rebuildability.
If the link is worn to approximately 120 per-
cent, structural damage may result in the
form of cracking, breaking and pin and
bushing loosening.
Wear Charts
Wear charts for links have a built in factor
allowing for faster wear rate as the hardness
of the steel decreases below the hardened
case depth. This is true for all components
where the allowable wear is greater than the
hardened case depth.
Different wear charts are provided for dif-
ferent links, and for the same link running
with different rollers, each of which is
determined by part number within a given
undercarriage or machine size.
Rebuildability
Track links can usually be successfully
rebuilt with submerged and/or automatic
welding to replace the worn away rail
(top) surface if the link meets the follow-
ing criteria:
1. Rail wear measured over the pin boss
is between 70 percent and 100 percent.
2. Unevenness of rail height is not excessive.
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LINKS
General Information