🔍 Key Concepts

• Fatigue failure in rolling element bearings usually starts below the surface and works its way out • Think about the earliest detectable symptom before anything becomes visually obvious on the main working surfaces • Consider how wear debris shows up in the lubricant compared to physical damage on races or rollers

💭 Think About

• Which sign would most likely appear first at a microscopic level, before a mechanic could easily see visible changes? • Do bearing races or rolling elements usually show visible cracking on the contact surfaces before or after subsurface fatigue has progressed? • How would early spalling or pitting begin to manifest—on the races, on the rolling elements, or primarily as contamination somewhere else?

✅ Before You Answer

• Focus on the word first in the question—this is about the very beginning of fatigue failure, not later damage • Compare the options that involve visible cracking versus those that involve contamination or subtle surface change • Ask yourself which component (races, rolling elements, or lubricant) would give the earliest reliable indication of subsurface fatigue starting to break through the surface