Consisting of a set of mechanical components that transmit the power of the engine to the propeller, a shaft line is of primary importance in the design and project stage, because it allows to transmit the mechanical energy produced by the propeller engine.
As a mechanical engineering firm, we process complete shaft lines or individual components, in particular propeller shafts, sterntubes and intermediate shafts.
A propeller shaft has the task of supporting the propeller, and is partially in contact with water; through a stop nut mounted in the threaded aft end, it is ensured that water does not enter the hull. The forward end of this axis is blunt-conical, so that the coupling with the propeller is forced and with interference.
A sterntube shaft, located between the forward and aft bearings, supports the propeller shaft, and prevents water from entering the hull; as for the propeller shaft, it has two visibly distinct extremities, the aft and the forward one, of different longitudinal dimensions (the former bigger than the latter).
Proceeding towards the bow from the propeller shaft, we find the intermediate shafts, the number of which depends on the overall length of the complete shaft line, which serve as connection between the different components.
The thrust bearings allow the transmission of the thrust created by the propeller to the entire structure of the hull, while the journal bearings, usually structured in two halves, function as support to the entire shaft line and maintain the correct support and alignment.
The elements that allow to connect the different shafts to each other are the so-called flanges, that is, rings positioned at their ends and held together by pins that allow the coupling (they are for this reason also called couplings).
In addition to processing complete shaft lines or individual components of them, as a mechanical workshop we process and supply a different motion system for vessels, which is a waterjet propulsion system. A water jet propulsion system is a system set in fast ships, hydrofoils, and motorboats, in the civil or military field, or large yachts, and is substantially composed of the following components: adduction duct, pump (axial or centrifugal), integrated or intubated impeller, supply duct and nozzle.
WATER JET STRUCTURE
As you can see from the figure above, the streamline enters from the opening situated under the hull, moves up to the adduction duct, up until the impeller, which is a metallic helicoidal that channels the water towards the pump and supplies the necessary power for the spurt. From here, the exit nozzle allows a higher turn maneuverability and navigability in shallow waters.
As a mechanical workshop, we process stator bowls, jetavators and reversing plates.
The Jetavator is a steering device, secured behind the stator bowl, and it allows to laterally deviate the water flow, thus creating the steering force. The jetavator can direct until 30° port and 30° starboard. This device includes the reversing plate, which allows to create the thrust towards the stern, on reverse.
The Reversing plate can be moved gradually, making it possible to transition from full speed onwards, from a position of stillness, to a reverse gear towards the stern and vice versa.
The Stator bowl is located behind the seat ring, and it allows to eliminate the rotational component of the water flow coming off the impeller. It is furthermore equipped with an integrated nozzle that allows to increase the flow’s speed, thus making the waterjet much more efficient and best-performing.
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