Before presenting the crosshead for survey after an unscheduled repair due to bearing failure, the following information should be provided to the Classification Society:
- Details of the bearing failure, including when and how it occurred, operating conditions, and the suspected cause of failure.
- Engine operating history, including running hours since the last overhaul or survey.
- Previous maintenance records, bearing clearances, and any earlier inspection reports.
- Details of the repairs carried out, including replacement of bearing shells or other damaged components.
- All measurements taken during dismantling, such as:
- Crosshead bearing clearance.
- Crosshead pin ovality.
- Guide shoe wear and clearances.
- Records of inspections of the lubrication system, oil holes, oil grooves, and lubrication performance.
- Any observations recorded in the engine logbook regarding overheating, abnormal oil flow, unusual noises, or vibration before failure.
The surveyor is likely to adopt the following inspection procedure:
- Obtain immobilization permission, isolate the engine, engage the turning gear, stop the lubricating oil pump, and open the crankcase doors.
- Position the crankshaft correctly and measure:
- Guide shoe clearance.
- Side clearance.
- Crosshead bearing clearance using a feeler gauge.
- Remove the bearing cap and dismantle both the upper and lower bearing halves.
- Measure the crosshead pin diameter at the top, bottom, port, and starboard positions to determine ovality.
- Present all measurements and components to the surveyor for examination before reassembly.
Areas requiring close attention (with reasons)
Crosshead bearing white metal
- Check for wear, wiping, cracks, discoloration, poor bonding, loose overlay, and squeezed white metal, as these indicate overheating, overload, or lubrication failure.
Bearing shell backside
- Inspect for proper seating, fretting, and cavitation damage, which may indicate movement of the bearing or poor contact with the housing.
Crosshead pin (journal)
- Examine for surface roughness, scratches, scoring, and ovality.
- Heavy wear, excessive scratching (more than one-third of the contact area), or excessive roughness may require renewal of the journal.
Lubrication system
- Inspect oil holes and oil grooves to ensure they are clean and undamaged, confirming proper oil supply to the bearing.
Guide shoes
- Check guide shoe wear and clearances to ensure correct alignment and proper distribution of bearing loads.
After reassembly, the surveyor will normally request the following information and observe the following operations:
Information requested
- Final measurements of:
- Crosshead bearing clearance.
- Crosshead pin ovality.
- Guide shoe wear and clearances.
- Confirmation that all damaged components have been repaired or renewed according to the manufacturer's specifications.
- Details of the lubrication system inspection and confirmation that oil passages are clean and unobstructed.
- Engine logbook entries and repair records documenting the failure and corrective actions taken.
Operations observed after reassembly
The surveyor will observe the engine during turning and initial running to ensure:
- Proper lubrication with uniform oil flow from the bearing oil grooves.
- No abnormal heating of the bearing.
- No unusual noise, vibration, or knocking.
- Smooth movement of the crosshead assembly.
- Bearing clearances remain within permissible limits.
Survey acceptance checks
The surveyor will also verify that:
- Crosshead bearing clearance is within the maker's recommended limits (typically 0.2–0.5 mm).
- Guide shoe surface clearance is within the maker's recommended limits (typically 0.25–0.55 mm).
- Guide shoe side clearance is within the maker's recommended limits (typically 0.1–0.2 mm on each side).
- Bearing surfaces are free from cracks, wiping, or other damage.
- Oil holes and oil grooves are clean and undamaged.
- The crosshead pin surface is smooth and within allowable ovality limits.
- The lubrication system functions correctly throughout the test run.