Lathe Plug saves time and cost

Pilgrim Admin


ALSTOM GENERATORS produced 30 to 35 Turbines per year between 45 to 175MW sizes. The design of the rotor shafts does not provide sufficient excess metal to allow for the ‘centre’ to be machined in to the end of the rotor shaft. Traditionally a plug was made for each rotor with a tight ‘dry fit’ in the blind hole, where the copper windings terminate. This was a painstaking task and was also problematic when removing the solid plug due to ‘pick up’ adding unplanned time to each job.

Having used extensively PILGRIM’S radial fitted bolt on turbine couplings they invited PILGRIM to design a hydraulically actuated tool that could replace the conventional solid plugs


Based upon PILGRIM’S Radially Fitted bolt technology the centre plug is hydraulically drawn into the matching sleeve. The resulting force in the sleeve causing its expansion creates a powerful and controlled radial force achieving a true interference fit within the rotor shaft and therefore accurately centring of the generator rotor in the lathe. Removal is also simple by using oil injection at the mating interface between the sleeve and the centre plug. Once separated the sleeve reduces in diameter to a clearance fit.


  • Trouble free removal
  • Accurate and predictable centring of the component.
  • Time saving 6hrs per Turbine x 35 Turbines per annum (210 hrs per year)
  • Removal of costly shop tooling