Definition
A soft, silvery bearing alloy made primarily of tin or lead with smaller amounts of antimony and copper, used as a lining material on the inner surface of plain bearings to provide a low-friction, conformable surface that supports a rotating shaft.
Plain English
A soft metal mixture coated onto the inside of bearings. It lets a spinning shaft turn smoothly against it, and because it is soft, it wears down before the more expensive shaft does.
Context Anchor
Seen in powerplant maintenance when inspecting or repairing engine bearing surfaces.
Derivation
Named after Isaac Babbitt, an American inventor who patented the alloy in 1839. Knowing it is a person's name explains why it is sometimes capitalized and why the word does not describe the metal itself.
Why Pilots Care
Babbitt bearings are sacrificial — they are designed to fail before the crankshaft or camshaft does. Recognizing the name helps a technician understand bearing wear reports and oil-filter findings during inspections.
Intuition Check
Do not think of Babbitt as the whole bearing or the shaft. It is the soft metal bearing surface that the shaft turns against.
Example Sentence 1
During the engine teardown, the technician noted that the babbitt on the main bearings showed normal wear and no signs of scoring.
Example Sentence 2
Excessive heat can melt the Babbitt material and cause the bearing to fail.