MARINE DIESEL ENGINES

Diesel engines are produced by many manufacturers  in a range of power outputs, 
for very many applications.The largest diesel engines are to be found in ships
and these operate on the 2-stroke cycle, which makes them quite unusual.
The piston is bolted to a piston rod which at its lower end attaches
to a cross head running in vertical guides, i.e. a cross head bearing. A connecting 
rod then transmits the thrust to the crank to turn the crankshaft. The arrangement 
is the same as on old triple expansion steam engine, from which they were earn. 
They have the further peculiarity of being able to run in both directions
by movement of the camshaft. This provides astern movement without the expense of what 
would be a very large gearbox.These very large engines are the first choice for most 
merchant ships because of their economy and ability to operate on low quality fuel.
A typical installation on a container ship, for a instance,would be a six cylinder 
turbocharged engine producing 20 000k Wat a speed of about 100 rpm. The engine is connected directly to a fixed-pitch propeller.