All anti-friction bearings require some form of

• A. Cooling
• B. Lubrication
• C. Heating
• D. Ventilation

Answer: (B)

Lubrication is essential because rolling bearings still have contact between surfaces, and a lubricating film kept between those surfaces dramatically lowers friction and wear. The lubricant creates a protective layer that allows the rolling elements to move with less resistance, distributes the load more evenly on the raceways, and reduces surface fatigue. It also helps carry away the heat generated by motion and protects against corrosion and contamination. Different forms exist—oil or grease are common—and some bearings are sealed and pre-filled with lubricant for life, but they still rely on that lubricant to function properly. Without lubrication, metal-to-metal contact would cause rapid wear and overheating, shortening bearing life. Cooling can be a helpful effect of lubrication, but it isn’t the fundamental requirement; lubrication is what enables the bearing to operate smoothly and durably.