JET 0035214 - Caterpillar

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Early wear on the inboard link side surfaceIn the first stage, sprockets and idlers begin wearing the link side surface. Refer to Illustration 22.
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Beginning of inboard seal exposureIn the second stage, link side surface wear has caused the beginning of seal exposure. Refer to Illustration 23.
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Advanced seal exposure allowing debris entryIn the third stage, advanced seal exposure allows debris to enter the seal cavity. Refer to Illustration 24.
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Debris entry damages the seal, causing oil leakageIn the final stage, the inner seal is damaged and begins to leak oil. This damage eventually causes the joint to go dry. Refer to Illustration 25.Inner Link Box Seal Exposure from Undercarriage Random Wear (RW)
Certain operational factors may cause the track to run in a more random nature against one or both side surfaces of the sprockets and idlers. This scenario causes a form of inner link side wear called Random Wear (RW). With random wear, the location and degree of inner seal exposure is inconsistent. Unlike thrust bias wear, random wear can cause several different seal exposure wear patterns. Some examples are:
Inner seal exposure on both inboard and outboard sides of the same track. Refer to Illustration 26
Inner seal exposure on one track only.
Inner seal exposure on the inboard side of one track and outboard side of the other track.In summary, any seal exposure wear pattern that is not specifically thrust bias wear is considered random wear.
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Random wear causing inner seal exposure on both sidesQuantifying the Severity of Inner Link Box Seal Exposure
Quantifying the degree of seal exposure is important in proper track management and track repair decisions. The first step is to clean the inside link boxes thoroughly that are to be checked for inner seal exposure.
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Seal exposure dimensionSeal exposure is determined by the distance from the inner link side face to the bushing end face of a wet joint. This exposure is shown in Illustration 27. Seal exposure is not relevant for a dry, pitch extended joint.Seal exposure is measured by one of two methods.
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1U-7234 Feeler Gauge to measure seal exposureOne method for measuring seal exposure is with a 1U-7234 Feeler Gauge . The gauge should lay flat on the link face and the measurement taken at the place of maximum gap, as shown in Illustration 28. This measurement should be done for three adjacent joints that are not extended or dry. Average the three joint measurements to determine the seal exposure dimension.
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4C-8733 Tapered Gauge to measure seal exposureAnother method for measuring seal exposure is with a 4C-8733 Tapered Gauge . The gauge should lay flat on the link face and the measurement taken at the maximum gap, as shown in Illustration 29. This measurement should be done for three adjacent joints that are not extended or dry. Average the three joint measurements to determine the seal exposure dimension.
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Incorrect seal exposure measurementAn incorrect measurement of seal exposure can lead to an improper maintenance decision for the track. Seal exposure