Diesel Engines

A slow speed or medium speed
Diesel engine is a
high pressure propulsion plant
with internal combustion.

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V-engine and in-line engine
In a V-engine the cylinders are placed in an oblique (or bevel) position, unlike the in-line engine, where the cylinders are placed “in line”.
V-engine
In-line
engine

Trunk engine
Crosshead engine
PISTON
CRANK
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PISTON
X
CRANKPIN

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2-stroke crosshead engine

The cylinder is filled with air.
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During the compression stroke the air in the cylinder is compressed.
cylinder

The atomizer (1)
sprays the fuel into the cylinder.
The nozzle
divides the fuel into
small particles.
1
atomizer
Tip of the atomizer
(nozzle).

During the power stroke the fuel is injected and burnt. This actuates the piston (1) and connecting rod (2).
1
2

The piston makes a
reciprocating motion.
Piston

1
2
3
The crosshead (1) serves as a hinging connection between piston rod (2) and connecting rod (3).
Crosshead guides and
crosshead guide shoes (4)
absorb the forces onto
the crosshead when the
piston goes down.
4

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The crank (1)
is connected to
the crankshaft (2).
1
2
Crankshaft

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The crank
changes the
reciprocating motion
of the piston into a
rotary motion
of the crank shaft .

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Gearwheels
to drive the camshaft
are driven by chains
(“chaindrive”).
camshaft

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The campeak is fixed to the camshaft.
campeak
campeak

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The push rod (1)
may be used as a
distance piece
between campeak (2)
and rocker arm (3).
1
3
2

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The exhaust valve (1)
is actuated (opened) by the
rocking lever (2)
(rocker arm).
2
1

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The exhaust valve
is actuated (closed)
by the
exhaust valve spring (1).
1

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The scavenging air manifold (1)
and
scavenging ports (2)
supply the
scavenging air
to remove the
exhaust gases.
1
2

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CROSS
SCAVENGING
LOOP
SCAVENGING
UNIFLOW
SCAVENGING

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The cylinder liner (1)
and cylinder jacket (2)
form the cylinder wall.
1
2
Cooling the cylinder:

A coolant (fresh water)
is injected between
liner and jacket
to cool the cylinder.
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Cooling the cylinder:

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Cooling the piston:
The advantages of oil as
a coolant are:
. it reduces noise;
. it purifies;
. it forms a seal;
. it lubricates;
. it is anti-corrosive;
. it has a higher resistance
to heat.
The piston is cooled by oil.

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The piston rings (1)
form a seal around the cylinder and
carry away the heat.
1
Piston rings

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4-stroke cycle

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During the
air induction stroke
(or inlet stroke,
or suction stroke)
air is drawn into
the cylinder.
Suction stroke

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During the
compression stroke
the air in the cylinder
is compressed.
Compression stroke

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During the power stroke
fuel is injected
and burnt.
Power stroke

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During the
exhaust stroke
the exhaust gases are
driven out of
the cylinder by
the piston.
Exhaust stroke