The total base number is especially needed for cylinder liner lubrication of engines that run on poor quality fuel with high sulphur content. The base additive is used to reduce corrosive effects of sulphuric acid fumes on cylinder.

With large diesel engine installations, lubricating oils are continuously filtered and purified to reduce insoluble particles in oil. Special strainers containing magnets are used to trap particles of carbon or iron particles. In large diesel engines, carbon particles are byproducts of combustion while iron particles comes from rubbing of gears, cams or other parts where wear down still occur.

The presence of these particles interferes with lubrication of bearings, most of which contain soft white-metal coating. The particles can become embedded into soft metal and cause abrasion of metal parts.

The contents of this page are part of a page from my e-book "General Engineering Knowledge Notes" that will help candidates prepare for Marine Certificate of Competency Examinations. This e-book is available for FREE downloading at Engineering Ebooks

Until next time...

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Once piston moves away from combustion space, pressure drops. The next stage of operation depends on design of engine. These can be either 2-stroke or 4-stroke designs.

Regardless of type of design, spent exhaust gas is first driven out, and then new fresh air is drawn back into combustion chamber.

After this, rotating crankshaft drives piston to compress fresh air inside combustion chamber. The piston acts as a reciprocating compressor at this stage.

The compression of air causes latter to become hot - hot enough to ignite finely distributed fuel particles.

At this moment, fuel is sprayed in at high pressure. The tiny sprayed fuel particles form a mist inside combustion chamber.

What do think will happen when you have heat, fuel and oxygen? A fire! Each tiny particle of fuel burns rapidly, and an explosion occurs.

The cycle starts again, and crankshaft turns continuously, pistons move continuously, and engine runs.

How does engine know when to spray fuel, let in air, compress air, and exhaust spent combustion product?

Well folks, start your engines.

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