A severe mechanical failure in a journal bearing system. It occurs when friction overcomes the locking mechanism holding the bearing shell in its housing, causing the shell to rotate alongside the shaft. This instantly cuts off the oil supply, leading to rapid overheating, galling, and total destruction of both the shaft journal and the housing.
We lost oil pressure on cylinder three and managed to spin a bearing before the shutdown tripped.
Spinning a bearing usually means an engine rebuild is required, as the housing is often bored out of tolerance by the spinning shell.
Also heard as
- spin a bearing
Related terms
Bearing
A machine element that constrains relative motion to a desired direction and reduces friction between moving parts.
Journal
The specific cylindrical portion of a shaft rests and rotates within a bearing.
Journal box
A protective housing that encloses a rotating shaft end and its bearing to retain lubricant and block debris.