Figure 24 Hub casting (shown assembled with pitch system and blade bearings), © Vestas.
Function
The hub connects the blades to the main shaft.
What it costs*
The hub casting cost varies significantly with rotor designs.
Who supplies them
Fonderia Vigevanese, MeuselWitz Guss, Sakana, Siempelkamp and Silbitz. Only some can manufacture the largest hubs for offshore turbines today.
Key facts
The hub is made of SG iron and weighs over 75 t. It houses the Pitch system [T2.6] and provides stiffened support for the Blade bearings [T2.5].
Generally, hubs are approximately spherical, with offset inner and outer surfaces to provide additional strength at the rear of the hub around the connection to the Main shaft [T1.3].
Openings are provided for personnel access. Lifting points for use during installation, support locations for pitch system components and other auxiliary systems and blind tapped holes are generally required.
SG iron is typically of grade EN-GJS-400-18U-LT, cast without the need to heat-treat. SG iron is chosen above cast steel due to superior pouring and shrinkage properties.
What’s in it
- Casting
- Non-destructive testing
- Machining
- Painting