Technical parameters of rudder support on plane friction:

Definition and Basic Principles

The planar friction upper rudder support is an important supporting component in the ship rudder system, mainly used to support the upper part of the rudder stock and withstand the axial and radial forces generated by the rotation of the rudder stock. It works based on the principle of plane friction, where the bottom plane of the rudder stock contacts the friction surface of the upper rudder support. When the rudder stock rotates, the stable rotation of the rudder stock is achieved through the frictional force between the planes. This friction force needs to be within a reasonable range, ensuring that the rudder can rotate smoothly while preventing excessive shaking or displacement of the rudder.

Structural composition

Friction pair:

The friction pair is the core part of the planar friction upper rudder support, including the plane at the bottom of the rudder stock and the friction plane of the upper rudder support. The bottom plane of the rudder stock usually needs to be finely processed to ensure its flatness and smoothness, reducing friction losses. The friction surface of the upper rudder bearing is generally made of wear-resistant materials, such as Babbitt alloy or special wear-resistant plastics. These materials have good wear resistance and self-lubricating properties, which can provide stable friction characteristics during the rotation of the rudder stock.

Bearing seat:

The bearing seat is used for installing and fixing friction pairs. It is a metal structure with sufficient strength and stiffness to withstand various forces transmitted from the rudder stock. The internal shape of the bearing seat is compatible with the friction pair, and the external part is firmly connected to the structure of the ship through bolts and other means. The design of the bearing seat should consider ease of installation, disassembly, and maintenance, while ensuring that the internal friction pairs can work stably during ship navigation.

Lubrication system:

In order to reduce the friction between the friction pairs, the rudder bearings on flat friction surfaces are usually equipped with lubrication systems. The lubrication system can be a simple oil cup or oil groove, which maintains lubrication of the friction surface by regularly adding lubricating oil. In some advanced designs, a centralized lubrication system may also be used, which can more accurately control the supply amount and supply time of lubricating oil. The function of lubricating oil is to form a layer of oil film between the friction pairs, reduce the friction coefficient, and also serve to cool and prevent wear.

Sealing device:

The sealing device is used to prevent lubricating oil leakage and external impurities (such as seawater, dust, etc.) from entering the interior of the bearing. It usually uses rubber seals or labyrinth seal structures. Rubber seals fill the sealing gap through their elastic deformation, providing a direct sealing effect. The labyrinth seal structure uses a series of complex channels to prevent the entry of liquids and impurities, which has a good sealing effect and can effectively protect the lubrication system and friction pair, extending the service life of the upper rudder bearing.

working principle

When the rudder stock rotates in the friction plane of the upper rudder support, the bottom plane of the rudder stock comes into contact with the friction plane of the upper rudder support. Under good lubrication, lubricating oil forms a layer of oil film between two planes. The rotational power of the rudder overcomes the frictional force between the friction planes, allowing the rudder to rotate stably. The magnitude of the frictional force between the friction planes depends on factors such as the friction coefficient of the friction pair material, the axial and radial forces of the rudder stock, and lubrication conditions. The bearing seat provides stable support for the friction pair, ensuring that the rudder does not experience excessive displacement or shaking during rotation. The sealing device ensures the normal working environment of the lubrication system and prevents external factors from interfering with the friction pair and lubrication system.

advantage

Simple structure: The structure of the rudder bearing on the plane friction is relatively simple, mainly composed of friction pairs, bearing seats, lubrication systems, and sealing devices. Compared with some other types of rudder bearings (such as roller bearings), it does not have complex rolling components, so the manufacturing process is relatively simple and the cost is lower.

High reliability: Due to its working principle based on plane friction, as long as the lubrication system works normally and the quality of the friction pair material is ensured, the rudder bearing on the plane friction can work stably. It has good adaptability to some small amplitude vibrations and impacts during ship navigation, and is not prone to failures caused by loose or damaged components.

Good bearing capacity: By designing the area and material of the friction pair reasonably, the rudder bearing on the plane friction can withstand larger axial and radial forces. This makes it suitable for various types and sizes of ships, meeting the support requirements of the rudder during normal navigation and turning processes.

Disadvantages and countermeasures

High friction loss: Compared with the rolling friction of the rudder bearing on the roller, the plane friction coefficient of the rudder bearing on the plane friction is higher, which will result in significant friction loss during the rotation of the rudder stock. In order to reduce friction losses, special attention needs to be paid to the maintenance of the lubrication system to ensure the quality and supply of lubricating oil. Friction pair materials with better self-lubricating properties can be used, and the wear of the friction pair should be checked regularly to replace severely worn components in a timely manner.

High lubrication requirements: The normal operation of rudder bearings on flat friction relies heavily on lubrication. If lubrication is poor, it may lead to a sharp increase in friction between the friction pairs, resulting in increased wear, difficulty in rotating the rudder, and even jamming. The response measures include installing reliable lubrication systems, such as automatic lubrication devices or oil cups with oil level monitoring functions, and regularly inspecting and maintaining the lubrication system to ensure that the lubricating oil can be supplied to the friction surface in a timely and effective manner.

Application scenarios

Small and medium-sized ships: In the rudder system of small and medium-sized ships, flat friction upper rudder bearings are a common choice due to their simple structure, low cost, and high reliability. The force borne by the rudder stock of these ships is relatively small, and the rudder support on the plane friction can well meet their support and rotation needs.

For cost sensitive ship applications: For some ships that are more sensitive to equipment costs, such as inland ships, small fishing boats, etc., the economic advantage of surface friction rudder bearings makes them a preferred type of rudder bearing. It can effectively control the cost of the rudder system while ensuring the normal navigation and steering of the ship.