A client required Alatas for these Kalmar STS Repairs to replace the right-hand hoist drum coupling on a Kalmar S2S crane as the existing Malmedie TTX 15 drum coupling had failed in service after nine months in operation. We have worked for this UK port client on numerous occasions, and the client opted for our professional service to carry out this work scope.
Several vital departments came together to deliver this project on time and to the client’s satisfaction.
Work Scope for Kalmar STS repairs
- Preparatory works
- Removal of right-hand side drum and pedestal including all accessories such as encoders, grease lines etc.
- Trial removal of the right-hand side coupling
- Once the coupling seized and damaged the driveshaft, the left-hand drum, coupling and pedestal was removed from the gearbox
- Removal of the gearbox c/w the seized right-hand drum coupling
- Overhaul of the gearbox at Bradford Workshop facility
- Re-installation of the overhauled gearbox c/w drum couplings to the drums and pedestal
- Alignment of the drum couplings
- Re-installation of all the ropes, encoders, emergency brakes etc.
Inspection at Port
Alatas mobilised to the site and was given no longer than three weeks by the client to carry out the coupling replacement. During disassembly of the coupling, the coupling was found seized to the shaft. Upon closer investigation, it was evident that localised heating (flame heating) had been used and this had caused damage to the shaft and coupling; therefore, the friction had badly scored the shaft.
The team of Alatas field service engineers soon realised it could not remove the right-hand drum coupling from the gearbox drive shaft. They had found the drum had seized on the shaft and tore out a portion of the drive shaft during removal.
Adaptive Work Scope
This damage changed the work scope from removing the coupling to overhauling the gearbox and repairing the drive shaft. To remove the gearbox, first, the Alatas team removed the left-hand drum and coupling. Then, after drawing up a lift plan on-site, the team lifted the gearbox using the crane down to the quayside.
The gearbox was sent to the Alatas Bradford Workshop for overhaul with only a one week lead time to return the gearbox to the site. With the seized/damaged coupling removed, the gearbox was completely disassembled and cleaned so that the Bradford Workshop could produce a full condition analysis.
Collaborating with Alatas Workshop
The Bradford Workshop then replaced all bearings and seals with new preordered parts at the client’s request after the damage to the drive shaft was identified. All other components were thoroughly cleaned, inspected, measured, and prepared for rebuild, whilst a new output drive shaft was manufactured using OCM technical information.
After our Workshop’s successful overhaul, we sent the gearbox to the site in time for installation with drum couplings installed to both output drive shafts using induction heating. This additional weight meant the gearbox now weighed approximately 5.5t which was above the SWL limit of the service crane.
Solutions from our in-house Engineering Team
The solution from our Engineering Team was to use a portable winch and a snatch block and swivel hook to lift the winch from the ground up to the crane machinery house (some 55m). Then, the drums and pedestal were installed, followed by the drum alignment and the left-hand side drum was aligned to OEM recommended angular misalignment.
However, the right-hand drum coupling could not be aligned with the pedestal’s existing mounting holes, which prevented the holes from lining up. This meant the pedestal holes had to be redrilled and local engineered modifications were carried out to suit. The pedestal was then re-installed, and the drum now aligned to the manufacturer’s recommended allowable angular misalignment. Next, the team aligned the electric motor and gearbox input drive shaft to the permitted misalignment before installing the main brake. Finally, the crane rope, brakes and encoder were re-installed followed by function testing and load testing of the crane.
The Alatas team completed the entirety of the work scope within the tight timescale. So the crane was returned to service for the client before the vessel arrived, meaning no downtime to their operations.
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