Which of the following is true regarding bearing maintenance?

• A. Over-lubrication of bearings can damage seal
• B. Lubrication never affects seals
• C. Under-lubrication is harmless
• D. Grease does not influence bearing life

Answer: (A)

Lubrication strategy must balance preventing metal wear with protecting seals. Seals are designed to retain lubricant and block contaminants, but they rely on proper lubrication levels and the right viscosity. Over-lubrication increases pressure inside the bearing housing and can cause the seal lip to deform or extrude, creating leaks and accelerated seal wear. Excess grease can also trap heat and degrade the seal material or force grease past the seal, contaminating the bearing. Because of these effects, over-lubrication can indeed damage seals, making this statement true. In contrast, lubrication does affect seals, under-lubrication is not harmless, and grease does influence bearing life; those other choices are not accurate.