The ship's marine engines are considered to be the biggest engines on earth with
massive power to propel a heavy loaded ship. There are different parts of the
marine engine which helps the engine to rotate the crankshaft and propel the
ship from one port to another. Each component plays an important role in
powering and running a marine diesel engine but the engine cannot run unless
all components are in place and are in working condition. The main engine of a
seagoing cargo ships are usually two-stroke internal combustion engines .
The working of the two-stroke engine can be understood from this video for a
marine engineer or a professional working on ships it is vital to know
different engine parts and their function to operate and troubleshoot
when needed. You must have seen the engine inside the machinery room of the
ship covered and assembled with different other auxiliaries. Let's take
it out from its installation and only concentrate on the main engine to
understand its different parts, but before proceeding further please do
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video. Looking at the exterior of the engine it comprises of the following Bed
plate- bed plate is the foundation block for two-stroke engine. It is built to
withstand the constant force from the engine but is also flexible enough to
handle constant fluctuations. A frame it is a fabricated steel structural element
of a slow-speed two-stroke diesel engine it stands on
the bedplate above the main bearings the a-frame carries the crosshead guides
and support the engine entablature also known as the cylinder block and
Entablature an entablature is a part of ships main
engine which houses the cylinder liner along with this scavenger space and
cooling water spaces. Turbocharger - Turbochargers are heat recovery
equipment helping to enhance the efficiency of the engine by supplying
fresh air they are located near the cylinder block check this video to
understand the turbocharger operation. Charge air cooler - charge air cooler is a
cooling arrangement for air supplied from the turbocharger before sending it
to the combustion chamber. It is usually located below the turbocharger and
adjacent to the scavenge space. Scavenge trunk - scavenge trunk is a space where
the cooled air from the charge air cooler is supplied for efficient
combustion. Cylinder head - It acts as a lid of the combustion chamber and
supports the exhaust wall and fuel injectors necessary for operation
Exhaust Vall - The exhaust wall helps to draw out the exhaust gases post the
combustion process. Know more about the functioning of marine engine exhaust
valve in this video. Exhaust trunk the exhaust drawn out of the exhaust wall is
then transferred to the exhaust trunk from where it strikes the turbine blades
of the turbocharger for heat recovery. It is located in between the cylinder head
and turbocharger unit. So these are the basic components which can be seen from
outside of the engine. Now let's dive inside the engine to understand
different rotating and moving parts that are involved in the propulsion process
that is the movement of the propeller. Liner it provides a durable and heat-resistant
combustion chamber preventing combustion products from escaping into the engine
itself. It is located at the top side of the entablature. Piston -- piston is used to
convert the force of expanding gasses into mechanical energy during the
process of combustion. It moves inside the liner and is connected to the cross
head by piston rod. Piston rings - it seal the piston therefore sealing the
combustion chamber preventing gases from leaking into the piston and surrounding
areas. Piston Rod -- it carries the piston and connects it to the crosshead
where the motion transfer takes place
Stuffing box - the crankcase is separated from the cylinder and scavenge space by a
diaphragm plate on a two stroke crosshead engine. The piston rod passes through a
stuffing box which is bolted into this diaphragm plate. The stuffing box
contains a series of scraper rings and sealing rings to seal and separate these
two spaces. Crosshead --A reciprocating block which usually slides in guides and
is the connecting point for piston rod and the connecting rod in a low-speed
two-stroke diesel engine. Connecting rod - The connecting rod is fitted between the
crosshead and the crankshaft. It transmits the firing force and together
with the crankshaft convert the reciprocating motion to a rotary
motion. Crankshaft -- It is the main component behind
transmitting power to the propeller shaft. The crankshaft on the large
modern two-stroke marine diesel engine can weigh over 300 tonnes they are too
big to make as a single unit and so are constructed by joining together
individual forging. Camshaft - The camshaft carries the cams which operates the fuel
pumps and exhaust valves. Because this operate once every cycle of the engine,
the camshaft on a two-stroke engine rotates at the same speed as the
crankshaft. Gear drive - Camshafts are driven either by gears or chains. In the
case of gear drive a train of gear wheel is fitted which transmits the drive from
the crankshaft to the camshaft.
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