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Integrally geared transmission for an ORC turbine

Pre-sizing a megawatt-class bull-gear transmission with three high-speed pinions at fixed centre distances.

a₁a₂a₃Bull gear
Industry
Energy
Year
2025
Sheet
2 / 7
Client
Manufacturer of ORC turbines
Duration
2 weeks for pre-sizing
Tools
KISSsys, KISSsoft
Standards
ISO 6336:2019

Bull gear with three pinions; centre distances a₁, a₂, a₃ fixed by the turbine layoutSchematic, not to scale

The question

The turbine layout fixed the bull-gear speed (below 1,000 rpm), the centre distances of three pinions and a pinion speed above 17,000 rpm. The question was which gear geometry fits these constraints with adequate safety, fast enough to inform the machine layout.

What the customer received

  • KISSsys system model of the transmission
  • Rating report for all meshes
  • Preliminary DXF and STEP data, two weeks after the order

Services: Gear and transmission calculation, Gearbox design

What we did

  1. Determined the optimal macrogeometry for each mesh within the given centre distances and ratios.
  2. Updated the KISSsys system model with the new geometry.
  3. Rated pitting and tooth root safety to ISO 6336:2019.
  4. Exported preliminary gear drawings (DXF) and 3D models (STEP) for the layout, to be finalised with microgeometry in the next phase.
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