Definition: The rudder stock is the axis of rotation of the rudder blade and is a key component of the ship's rudder device.
Function: It is mainly used to bear and transmit the force acting on the rudder blade and the force applied by the rudder blade to the steering device, so that the steering gear rotates the rudder blade through the rudder stock, and the rudder blade bears the reaction force of the water on it, thereby realizing the turning of the ship.
Structural Features
Overall structure: It is usually a slender rod-shaped structure, one end of which is connected to the rudder blade and the other end is connected to the steering device or steering gear.
Connection structure: The fit between the rudder stock and the tiller can be achieved through a conical tight fit or a cylindrical transition fit, and the connection usually uses an ordinary flat key. The fit between the rudder stock and the upper rudder bearing and the lower rudder bearing is usually a dynamic fit, and the fit with the rudder pintle is selected in different ways according to the shape of the end of the rudder stock.
Material selection
Common materials: Generally, good forged steel materials such as 20Mn are selected to ensure sufficient strength and toughness to withstand the various forces on the rudder blade during the navigation of the ship.
Special materials: For some high-end ships or ships with extremely high corrosion resistance requirements, stainless steel and other materials may be used to manufacture the rudder stock to improve its corrosion resistance in the seawater environment.
Design requirements
Strength requirements: The strength of the rudder stock is very important. When designing, it is necessary to ensure that it can withstand the pressure, torque and bending moment of the rudder blade.
Diameter requirements: For double-pivot rudders, the diameter of the rudder stock can be gradually reduced from the top of the rudder blade to the bottom, but the minimum diameter should not be less than 0.75 times the diameter of the lower rudder bearing. For single-pivot suspension rudders, the diameter of the rudder stock can be reduced from the top of the rudder blade to 0.4 times the diameter of the lower rudder bearing.
Manufacturing process
Forging process: Generally, the forging process is used for manufacturing. By heating and forging the blank, it is formed into the required shape and size to improve the density and mechanical properties of the material.
Machining: The forged rudder stock needs to undergo a series of machining, such as turning, grinding, drilling, etc., to ensure its dimensional accuracy and surface quality and meet the requirements of matching with other components.
Maintenance and repair
Inspection items: including inspection of the rudder shaft diameter, surface condition, matching with the tiller, flange working surface and cracks.
Repair method: Slight rust spots are allowed on the working journal surface of the rudder shaft, but the depth is limited. The reduction of the non-working journal and the diameter reduction of the working journal after polishing are also specified. For the rust and strain of the matching journals of the rudder shaft and the tiller shaft, as well as the corrosion of the flange working surface, repairs need to be carried out according to the specific situation.
Dongtai Haipeng Marine Accessories Co., Ltd. is a professional manufacturer that designs, manufactures and processes all kinds of ship stern shafts, rudder shafts and their supporting products, stern shaft seals, stern tube bearings, upper and lower rudder bearings, intermediate bearings, bulkhead transmission devices and other ship supporting products.
