In-situ Crankpin Grinding
A damaged crankpin is ground to an undersize with a portable grinding machine and polished, without removing the crankshaft from the engine.
The work is done at the shipyard or port where the vessel is. Because the crankshaft stays in place, the engine does not have to be fully dismantled and the crankshaft does not have to be shipped to a workshop.
Photos from the Job
Process Steps
When It Is Needed
- After a bottom-end bearing failure leaves the pin scored, smeared with bearing metal or discoloured
- When ovality or taper exceeds the engine maker's limit
- When hard spots or cracks are suspected after a seizure
Scope and Limits
- We do not supply bearing shells; the undersize bearing is supplied by the owner or the agent.
- If the required undersize exceeds the engine maker's limit, grinding cannot save the pin; the decision then lies with the owner, the engine maker and class.
- Crankshaft straightening is not part of this service.
Frequently Asked Questions
How is a crankpin ground without removing the crankshaft?
The grinding machine is mounted on the pin. The pin stays still and the machine rotates around it; grinding is followed by polishing.
Which bearing is fitted after grinding?
The engine maker's undersize shell matching the finished diameter in the report. The owner or the agent supplies it.
How much can be taken off the pin?
The engine maker's undersize limit decides. After measuring, we report the undersize required and where it stands against that limit.
What pin diameters can you grind?
On board we grind crankpin diameters from 200 mm to 550 mm.
Is crankpin grinding the same as crankshaft grinding?
On site the job is often simply called crankshaft grinding. What is ground is the pin on the crankshaft that the connecting rod runs on: the crankpin.
Contact Us Now
Tell us the engine make and model, the damage and where the vessel is; we will review it and get back to you.
Request a QuoteOther Services
10 servicesOther reconditioning work we do on board and in the workshop.
- Stress relieving (heat treatment)
- Inspection and reporting
- Crankpin polishing
- Laser alignment check
- Cylinder liner honing
- Liner seating face grinding
- Crane seating face grinding
- Workshop machining
- Connecting rod crack testing
- Liner flange underside grinding