Diesel Marine Engines

The marine diesel engine is an advanced apparatus, allowing for the combustion powered operation of vessels on water. Generally, a marine engine may either be inboard or outboard, meaning that the engine may be implemented within the hull of a boat or mounted upon the hull itself. Regardless of which type of diesel engine is present on a marine vessel, many share the same components and systems that allow them to operate efficiently.

Depending on the marine engine in question, operation may either follow a 2-stroke or 4-stroke pattern. With a 2-stroke engine, the piston rises through the power of air that is forced into the chamber, and it causes it to rise so that fuel is injected within the combustion chamber. As the piston slams back down, it ignites the fuel for a power output. As a system that functions well for low speed engines and larger vessels, the 2-stroke engine follows a simple compression and power output cycle during functionality. The 4-stroke engine, on the other hand, is much more similar to that of an automobile, turning a crankshaft while operating through an intake, compression, combustion, and exhaust cycle.

Serving as the foundation block of the marine engine, the bedplate provides a strong and flexible base for the engine to operate, and it is robust enough to withstand the forces exerted by the engine. To construct the bedplate, two girders are implemented across the engine’s length, and they are then connected together with transverse girders. To provide more support to loads, cast steel bearing supports are fastened to the transverse girders.

To transfer power from the diesel engine cylinder to the propeller shaft, a crankshaft is used. Composed of various metals and resistant materials, the crankshaft is designed to withstand high amounts of bending and shear stress to avoid damage from fatigue. Depending on the system, the crankshaft may be designed in four ways which are the fully build up, one piece, semi build up, and welded construction types. With a connecting rod, the crankshaft is attached to either a crosshead or a gudgeon pin based on whether the diesel engine is two- or four-stroke.

To ensure proper combustion of the fuel, a series of pistons, fuel injectors, cylinders, and liners are needed. Within the combustion chamber of the marine engine, pistons allow for the expansive gases produced by combustion to be harnessed for the creation of mechanical energy. With fuel injectors supported by a cylinder head, fuel can be sprayed into the combustion chamber for proper mixture and ignition. Due to the immense heat generated by the ignition of fuel mixtures, thin metal liners and a cooling system are implemented in order to provide heat resistance to the combustion chamber for the protection of parts.

In more modern marine vessels, a turbocharger or turbo compressor may be present within the power plant, that of which dramatically increases the efficiency of combustion. With the turbo compressor or turbocharger, turbine blades increase the pressure of gases passing through the turbine, creating an optimal amount of power for propulsion. To assist in increasing pressure and creating air suction, a blower may also be present within the system.

To ensure that your marine engine continues to operate efficiently, strict maintenance and inspection scheduling should be followed, and damaged parts should always be immediately repaired or replaced. When you are in need of reliable marine parts such as freeze plug components or fuel filter parts, let the experts at NSN Sourcing help you secure everything you need to carry out your operations with ease. NSN Sourcing is a leading distributor of aircraft parts, marine parts, and more, providing customers access to over 2 billion new, used, and obsolete items. Peruse our robust part catalogues at your leisure, and you may request a competitive quote at any time by filling out and submitting an Instant RFQ form through our website. Get started today and experience how we are revolutionizing the parts procurement process for our customers.


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