- Design based on proven technology
- Delivered pre-machined for flexibility on site
- Suitable for either new-build or retrofit applications
How a stern tube bearing works
The function of the stern tube bearings is to carry the radial loads of the propeller shaft and to protect the shaft against wear. In the case of an oil-lubricated bearing, this is achieved by creating an oil film between the bearing and the propeller shaft. When the propeller shaft is rotating, nearby oil will follow the circumferential movement of the propeller shaft.
At sufficient shaft speed, the oil will flow from the supply holes in the bearing along with the shaft towards the bottom of the bearing. Here it is forced between the narrowing space between bearing and shaft, which creates lift. When the shaft speed is high enough, there will be no metallic contact between the shaft and bearing. This principle is called hydrodynamic lubrication.
Materials & options
Our stern tube bearings are suitable for oil- and grease-lubricated systems with shaft diameters that can vary from 70mm till approximately 900mm. Lagersmit bearings can be delivered with a class approval/certificate upon request and have several options;
- Aft, intermediate or forward stern tube bearings
- Temperature sensor for measuring bearing metal temperature
- Different grades of cast iron
- Different types of white metal, including lead- and tin-based white metal
- Delivery in pre-machined condition, with or without oil supply holes and longitudinal grooves
The bearings are made out of a cast iron bush with a white metal lining on the inside. There are two types of white metal;
- lead based
- tin based
In most cases lead based white metal will be sufficient for stern tube bearing applications and will also be the most economic option. For ice-class, navy vessels or environmental regulations we recommend tin-based white metal lining. Tin based white metal is more suitable when dynamic loads can occur.
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Jan Willem Bongers