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What's Been Updated?
Section 8: Bearings
This section adds guidance and tools for identifying counterfeit and gray market bearings, emphasizes accurate measurement of bearing dimensions before mounting, clarifies installation methods for larger bearings using controlled-temperature ovens or induction heaters, and updates maximum heating-temperature cautions to protect bearing metallurgy and lubricant integrity. For consistency, all instances of terms “ring” and “race” in the text and graphics were replaced with “ring (race).”
Revisions in this section also clarify the limits of vibration spectral detection and urge service centers to make vibration reports more useful to customers by including operating conditions (voltage, current, speed and load).
Bearing reliability explanations and calculations were updated as needed to ensure correct, consistent use of the L10 and L10h symbols, and greater emphasis was given to the risks of grease incompatibility and clogged/caked grease cavities or exit piping.
To improve bearing failure diagnosis, the bearing fatigue stages and some inspection questions were revised, and some outdated information was replaced with Tom Bishop’s paper “Dealing with Bearing Currents.” Importantly, too, the bearing failures photo reference library was replaced with images and information provided by Timken Bearing Corp.
Section 9: Lubrication
Revisions in this section clarify guidance on bearing lubrication and its direct effect on motor repair quality and reliability. For example, updated wording now more clearly warns that prolonged operation of an over-greased motor can impair cooling and contribute to premature bearing failure. The addition of an oil mist lubrication illustration and a detailed explanation of forced (circulating) oil systems improve understanding of lubrication methods critical to reliable motor performance. Renaming Table 9-4 the “Grease Incompatibility Chart” is another key improvement, highlighting the risks of mixing incompatible greases. Together, these changes give service centers clearer, more practical guidance for avoiding repeat failures and improving customer outcomes.
Section 10: Mechanical
The most significant changes in this section include enhanced guidance on vibration baselines, filtered measurements, units, sensor placement, frequency terminology and limits, and their relevance for VFD-driven applications. Outdated alignment procedures were also removed, and bearing-life terms L10 and L10h were corrected as needed. Keyseat data was updated to current international standards, and 200M frame data was added to IEC shaft extension and keyseat dimensions.
Other revisions included correcting errors in Recommended Copper Welding Cable Sizes, improving weld joint illustrations, adding metric V-belt sizes and profiles, revising the lifting capacity explanation and illustration, and replacing the Permissible Shaft Runout table with ANSI/EASA AR100– 2025 Table 2-3. References to international standards (e.g., ANSI/EASA AR100-2025, ANSI/NEMA MG 00001-2024, and ISO 21940-11:2016) were also updated. Collectively, these changes enhance the section as a standards-aligned reference for better diagnostic accuracy and service quality.
Section 11: Formulas & Conversion Factors
Although the Technical Services Committee’s review of this section resulted in no substantive changes, it did identify and correct two typographical errors. References to international standards were also updated to the current versions.
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