explain:

For ships sailing in the Yangtze River and inland rivers, and when the working medium of the stern tube is oil and the stern shaft is not large, it is recommended to use this type of bearing.

Definition and Function

The stern shaft bearing is a key component in the ship's power system, installed on the stern shaft of the ship. Its main function is to support the weight of the stern shaft while reducing the frictional resistance during rotation, ensuring smooth and efficient operation of the stern shaft. During the navigation of a ship, the stern shaft is subjected to various forces such as the thrust of the propeller, its own gravity, and the force of seawater. The stern shaft bearings can effectively disperse these forces and prevent excessive deformation or damage to the stern shaft.

For example, when a ship is sailing, the high-speed rotation of the propeller transmits a large amount of torque through the stern shaft. The stern shaft bearing acts as a "buffer", evenly distributing these forces on the bearing seat and hull structure, enabling the stern shaft to work stably.

Main types

Oil lubricated stern shaft bearings:

This type of bearing uses lubricating oil to reduce friction. Its structure is relatively complex, generally including bearing seat, bearing shell, and lubricating oil supply system. Bearing shells are usually made of materials such as Babbitt alloy, which has good wear resistance and anti friction properties. The lubricating oil supply system will continuously deliver lubricating oil to the gap between the bearing and the stern shaft, forming an oil film. The oil film can completely separate the stern shaft and the bearing shell, turning the friction between them into liquid friction and greatly reducing the frictional force.

For example, in large ocean going vessels, oil lubricated stern shaft bearings are widely used. The main engine power of a ship is relatively high, and the load borne by the stern shaft is also high. Oil lubrication can well meet its operational requirements.

Water lubricated stern shaft bearing:

Using water as a lubricant, its bearing structure is relatively simple. Generally, the bearing liner made of rubber or other polymer materials is in direct contact with the stern shaft. Water forms a lubricating film between the stern shaft and the liner, which reduces friction. The advantages of this type of bearing are environmental friendliness, low cost, and the ability to avoid safety hazards caused by lubricant leakage.

For example, in some small ships or ships with high environmental requirements, such as water yachts, inland ships, etc., water lubricated stern shaft bearings are a more suitable choice.

Material requirements

Good wear resistance: Both oil lubricated and water lubricated stern shaft bearings need to have good wear resistance. Because during the rotation of the stern shaft, friction is constantly generated between the bearings and the stern shaft. If the wear resistance is poor, the bearings are easily worn, resulting in a decrease in the accuracy of the stern shaft and affecting the normal navigation of the ship. For example, the bearing material of oil lubricated bearings is Babbitt alloy, which has moderate hardness and can maintain good wear resistance during friction with the stern shaft.

Corrosion resistance: Due to the navigation of ships in water, stern shaft bearings inevitably come into contact with seawater. Seawater has strong corrosiveness, so bearing materials should be able to resist the corrosion of seawater. For water lubricated bearings, the lining material such as rubber needs to have good resistance to seawater corrosion; For oil lubricated bearings, anti-corrosion treatment is also required for components such as bearing seats and bushings, such as using anti-corrosion coatings.

Sufficient strength and toughness: The stern shaft bearing needs to withstand various forces such as the weight of the stern shaft and the thrust of the propeller, so it needs to have sufficient strength to prevent deformation and damage. At the same time, in order to avoid brittle fracture under impact and other conditions, bearing materials also need to have a certain degree of toughness. For example, some metal bearing seats are made of high-strength alloy steel to meet the requirements of strength and toughness.

Key points for installation and maintenance

Installation process:

When installing the stern shaft bearing, it is necessary to ensure the installation accuracy of the bearing seat first. The bearing seat needs to be firmly installed on the ship structure, and the levelness and verticality of its installation plane must meet the requirements. For oil lubricated bearings, when installing the bearing shell, attention should be paid to the fit between the bearing shell and the bearing seat, and there should be no gap, otherwise it will affect the formation of the oil film. For water lubricated bearings, the installation of the liner should ensure that there is a suitable gap between its inner diameter and the outer diameter of the stern shaft to ensure good water lubrication effect.

Maintenance points:

Regularly check the wear of bearings. For oil lubricated bearings, it is necessary to check the wear of the bearing shell, the quality of the lubricating oil, and the oil level. If the bearing is severely worn, it needs to be replaced in a timely manner; If the lubricating oil deteriorates or the oil level is too low, it should be replenished or replaced in a timely manner. For water lubricated bearings, it is necessary to check the wear and aging of the bushings, as well as whether the water lubrication system is unobstructed. Meanwhile, it is important to prevent seawater impurities from entering the bearings and regularly clean them.