Speedy repair to gearbox
January 1st 2005

Meeting a tight deadline, the Transline division of Wyko Industrial Services has repaired a speed increaser gearbox at a sewerage treatment plant in North London.

Condition monitoring reports showed that white metal lined bearings in the unit were failing and needed to be replaced against the clock to avoid unplanned downtime. With an output of up to 6000rpm, the bearings had to be fitted to the input and output shafts of the 3.486:1 unit, a process that involved altering the bores to within very tight tolerances.

On a routine condition monitoring survey by Engenica at the Thames Water plant, the speed increaser gearbox showed unusually high thermographic readings.

Engenica contacted Wyko who removed the 1.25t unit and took it to its Transline division for further examination.

The company was commissioned to carry out repairs on the basis of a three to four week turnaround. To replace the full set of bearings was no easy task, as the white metal lined designs needed to be machined and seats hand scraped to produce the special bores. Wyko achieved the correct running clearances of between 0.004 and 0.006in.

Once the bearings were fitted, all rotating parts of the gearbox were dynamically balanced and Wyko reduced the residual imbalance to lower even than the original design calculations.

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