Modern hydro turbines present extraordinary engineering challenges. In large vertical units, thrust bearings must support axial loads exceeding 6,000 tons—the combined weight of the rotor, turbine runner, and hydraulic thrust. Today’s single-unit capacities have reached 889 MVA with turbines of 800 MW in facilities such as China’s Xiangjiaba Hydropower Plant. This article provides a comprehensive overview of hydro turbine bearings, examining their types, materials, design considerations, operational challenges, and emerging innovations.
Hydro turbine bearing systems generally comprise two fundamental categories, each serving distinct functions.
Thrust Bearings
Thrust bearings bear axial forces—the vertical load transmitted along the shaft from the weight of rotating components and the axial hydraulic thrust on the turbine runner. In most hydro turbine thrust bearings, a tilting pad design is adopted to increase load capacity and improve unit stability. These bearings transfer substantial axial load from rotating to stationary components via a thin lubricating film with extremely low friction and practically no wear.
The history of modern thrust bearings traces back to 1912, when the Kingsbury thrust bearing—with a thrust load of 184 tons—was first applied at the Holtwood Hydropower Plant in Pennsylvania, USA. This innovation made it possible to design much larger hydroelectric units with substantial axial loads.
Guide Bearings
Guide bearings absorb radial loads and keep shafts aligned. Positioned along the vertical shaft, they keep the rotor centered in the stator. Guide bearings may feature fixed geometry or tilting pads and can be either oil-lubricated or water-lubricated.
Combined Bearing Systems
In many hydro turbine configurations, both thrust bearings and guide bearings are housed in a shared oil tank, where oil circulation interacts, resulting in complex lubrication behavior. Although the two bearings share an oil tank, their lubricating oil films operate independently, while temperature and pressure distribution within the tank is jointly determined by both bearings.
Post time: Jun-22-2026
