How many stern tube bearing are there and how are they connected with stern tube?Material of bearing and why white metal does not rotate with shaft?
- Stern tube bearings generally consists of two ( fwd and aft ) bearings which are pressed in and secured to the stern tube the bearing sleeves are made of high strength ductile iron and centrifugally lined with high tin base babbitt.
- The bearing bore is normally finish machined to fit the propeller shaft and outside diameter is semi finished for final machining in shipyard.
Two procedures are commonly used for fitting stern tubes
- The stern frame is finish machined.The stern tube is pressed in and secured by bolting or welding .The stern tube is bored and bearings are then pressed into stern tube
- In the second procedure, the stern tube is bored in the shop and fitted with its bearings then the entire assembly is pressed into the stern frame at shipyard. Boring of stern tube to provide an interference fit