Which bearing is most commonly used to support the crankshaft?

Which bearing is most commonly used to support the crankshaft?

• A. Insert Bearing
• B. Ball Bearing
• C. Sleeve Bearing
• D. Journal Bearing

Answer: (A)

The crankshaft is mounted on main bearings that provide a smooth, replaceable wear surface for the journal. In most automotive engines, these are insert bearings—the bearing shells with a soft metal lining that fit into the engine block and surround the crankshaft journals. This design creates the precise clearance needed for the oil film to form, allowing efficient lubrication and load support while still being economical and serviceable. Ball bearings aren’t used for crankshaft supports in typical engines because rolling elements don’t handle the radial and thrust loads as well in this lubrication regime. Sleeve or plain bearings describe the general type, but the common, replaceable shell form—insert bearings—is what’s routinely specified for crankshaft support in most engines. The term also reflects the practical maintenance advantage: worn shells can be replaced during rebuilds to restore proper clearances.

The crankshaft is mounted on main bearings that provide a smooth, replaceable wear surface for the journal. In most automotive engines, these are insert bearings—the bearing shells with a soft metal lining that fit into the engine block and surround the crankshaft journals. This design creates the precise clearance needed for the oil film to form, allowing efficient lubrication and load support while still being economical and serviceable.

Ball bearings aren’t used for crankshaft supports in typical engines because rolling elements don’t handle the radial and thrust loads as well in this lubrication regime. Sleeve or plain bearings describe the general type, but the common, replaceable shell form—insert bearings—is what’s routinely specified for crankshaft support in most engines. The term also reflects the practical maintenance advantage: worn shells can be replaced during rebuilds to restore proper clearances.