Main Bearings - Main Engine and Propulsion

Main bearings are hydrodynamic plain bearings supporting the crankshaft of marine diesel engines and propulsion machinery. Typically split-shell or segmented designs, they operate on a pressurized lubricating-oil film and are selected specifically for the engine type and crankshaft dimensions.

ProShipWorks provides end-to-end support to source and supply Main Bearings for marine vessels, ship operators, industrial facilities, maintenance teams and procurement departments.

Last updated: October 11, 2026

Product Information

Product Name	Main Bearings
Product Category	Main Engine and Propulsion
Product Reference	9
Brands / Manufacturers	MAN Energy Solutions, WinGD, Miba
Unit of Measure	Piece or Set

Key Features

Key Feature
1. High load-carrying capacity under continuous marine duty
2. Replaceable split-shell or segmented construction
3. White-metal or multilayer bearing surface
4. Pressurized lubricating-oil grooves and passages
5. Engine-specific dimensions, clearances and oil-film requirements

Applications of Main Bearings

Application
1. Main crankshaft support in two-stroke marine propulsion engines
2. Main crankshaft support in four-stroke marine diesel engines
3. Journal support in marine propulsion and reduction machinery

Models & Manufacturers

Model	Manufacturer
MAN B&W ME-C engine series main bearing	MAN Energy Solutions
MAN B&W MC-C engine series main bearing	MAN Energy Solutions
X engine series main bearing	WinGD

Technical Specifications

Model	Specification	Value	Unit
MAN B&W ME-C engine series main bearing	Bearing type	Split hydrodynamic plain bearing	—
MAN B&W MC-C engine series main bearing	Lubrication	Pressurized system lubricating oil	—
X engine series main bearing	Bearing surface	White-metal lined, engine-specific construction	—

Standards, Certifications & Class Approval

Review the available standards and approval information relevant to the product. Actual certification, material traceability, inspection and classification requirements depend on the product type, intended application and purchasing specification.

Applicable Standards & Certification	Applicable references may include ISO 4378 for plain-bearing terminology, ISO 3548 for thin-walled half-bearing dimensions and tolerances where applicable, and OEM material, clearance and inspection specifications. Main bearings are normally supplied and accepted as engine-specific components.
Class Approval	Acceptance is normally linked to the approved engine design and OEM documentation under rules of societies such as DNV, ABS, Lloyd's Register, Bureau Veritas and ClassNK. Individual replacement bearings may require material certificates, dimensional records and class surveyor acceptance.

Installation, Maintenance & Safety Information

Installation Notes	Confirm the exact engine type, bearing position and OEM part number. Clean the housing and journal, verify shell orientation and oil-hole alignment, measure journal condition and bearing clearance, and tighten bearing-cap fasteners using the OEM sequence and specified hydraulic pressure or torque.
Maintenance Tips	Monitor lubricating-oil pressure, temperature, contamination and bearing-temperature trends. Inspect removed shells for wiping, fatigue, cavitation, scoring or edge loading. Check crankshaft deflection, journal dimensions and clearances at OEM intervals; renew bearings only within approved limits.
Safety Notes	Isolate starting systems, engage the turning-gear interlock and secure the crankshaft before work. Support heavy caps and shells with approved lifting equipment. Never enter the crankcase until ventilation, cooling, lockout and hot-work or enclosed-space procedures are satisfied.