Being well known for our repair capabilities, we repair damaged two- and four-stroke engine flywheels frequently. In most cases, a few of the flywheel’s teeth are damaged and we quickly restore these by installing a tailor-made repair insert. We usually do this in-situ, either during a port stay or during a docking.
The situation found on an European-owned 2’300 TEU box ship in September 2022 was very different. When the customer contacted us about a damage to the flywheel, we sent our colleagues from QuantiServ Singapore on board for an inspection.
During the inspection it very quickly became clear that this was no ordinary case, as all ninety teeth were found severely damaged. An in-situ repair of 90 teeth would take too long and would not be cost-efficient either. As the ship was about to be docked very soon, we suggested to the customer to carry out the repair during the upcoming docking in southern China.
The colleagues from QuantiServ China took over the case. They worked out a very attractive proposal that was immediately accepted by the customer. Our engineers and technicians then started all preparation and planning.
Once the vessel was in the yard, the yard workers uncoupled the intermediate shaft, took the 3.5 ton flywheel off the engine and moved it out of the engine room through a narrow slot that they had cut into the vessel’s hull. The flywheel was then trucked to Shanghai, where the highly-skilled engineers and technicians from QuantiServ China immediately commenced to machine it.
They machined off its toothed rim and then shrunk on a tailor-made ring of forged steel onto the ø 3.2 meter flywheel. And to make sure that the ring stays put for the lifetime of the ship, they also installed a total of 135 large bolts. Once this was completed, new teeth were milled.
Milling new teeth obviously took time, owing to the large size of the flywheel. In fact it took five days and five nights of continuous milling!
After completing a few more processing steps, our Shanghai colleagues sent the flywheel back to the shipyard and to a very happy customer. The shipyard workers then completed this repair assignment, by reinstalling the flywheel to the 72-bore engine and by re-coupling it to the ship’s intermediate shaft.
The repair of every single tooth on a flywheel as presented above is not something that we do every day. Typically, just a handful of consecutive teeth are damaged. Follow one of the links below to see how we repair these cases in-situ.