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Close co-ordination ensures swift and simultaneous crankshaft and rotor exchange in Singapore



Key Benefits:

Multiple removal and installation techniques

Coordination with several project teams

Short notice mobilisation

Reduced schedule

Bespoke solution


ALE has used multiple techniques to swiftly perform two operations simultaneously within a highly challenging environment. The exchange of a crankshaft, weighing 9.2t, and the removal and re-installation of a rotor, weighing 24.2t, were both completed onboard a cruise ship in under two weeks.

ALE had to coordinate the project’s manoeuvres, along with over a thousand other subcontractors, some of whom were working in the engine room at the same time. Prior to the start of the project, ALE came aboard the vessel to ensure essential preparations were in place and enabled the mobilisation to be as quick as possible.

The company’s diverse experience of working in complex project environments ensured that the great deal of coordination needed within ALE’s own team was maintained while both the operations were carried out at the same time, and this thorough planning enabled time savings.

Koen Harthoorn, Project Engineer, said, “This project involved a lot of logistical challenges as ALE had to mobilise at short notice and then complete both jobs within 12 days. It was essential that we maintained communication with the other subcontractors, before and during the operations, as there were around 1,500 other employees onboard carrying out their own works.”

First, for the crankshaft exchange, ALE installed specially-designed jacking brackets to the side of the engine block and 5t capacity chains were attached to the top of the engine. Single acting jacks carried out the first jacking stage to create sufficient height for 60t capacity climbing jacks to be installed. The engine block, weighing 52.5t, was then jacked-up 1.3m in 13 stages of 100mm.

ALE set the engine block down on temporary supports and used chain blocks to lower the crankshaft into saddles, which were placed on skid beams. The crankshaft was then skidded from underneath the engine block. The overhead crane, turntable and skidding system were used to rotate the crankshaft and transport it from the engine room through a hole in the ship’s side. Two cranes lifted the crankshaft out of the vessel and manoeuvred the new crankshaft inside.

ALE then carried out the procedure in reverse to transport and position the new crankshaft under the engine block. The crankshaft was lifted back into its bearings using the chain hoists. To complete the crankshaft exchange, the engine block was jacked-down and adjusted into its final position.

For the removal of the rotor, ALE first used single acting jacks with specially-designed jacking brackets to jack-up the alternator housing by 30cm. This enabled ALE to move the rotor just above the foundation and assist the client with the removal of the bearings and end shields. Extension pieces were attached to the shaft of the rotor, which ALE lifted using 20t capacity chain hoists, enabling the rotor to be removed from its housing.

Once outside the alternator, the rotor was set down on roller skate brackets, so it could be rotated for the client. After the client had completed their work, ALE reinstalled the rotor in its housing and it was jacked-down.

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