Diesel engine is generally classified as follows
according to operation speed :
Low Speed: Below 350RPM
/ Intermediate Speed: 350~1000RPM / High Speed:
1000RPM or more
The low speed engine is
used for the propulsion of container vessels
or tankers more than 10,000 tons.
Intermediate speed or high speed engine is used
for car ferries or fishing boats in general
or widely used as auxiliary power.
A recent trend shows use of intermediate engines
of larger cylinders for large vessels, while
smaller-dimension and lower speed engine offers
beneficial points in propelling transport ships.
All low-speed engines are designed to use residual
fuel, while intermediate-speed engine can use
residual fuel or distillate fuel or residual
oil depending on operation types and a high-speed
engine always uses distillate fuel.
All the engines today are the single acting
type, having only one combustor at the top of
the piston. The main driving stroke is as follows:
While the crank shaft rotates twice in a four
stroke engine, each cylinder will have one power
the suction stroke sucks the air into the cylinder.
the compression stroke increases temperature by
injected when the piston reaches the top dead
center of the
in the power stroke, fuel combusts when
it contacts with heated air and the
increased air pressure pushes the piston to the
in the exhaust stroke, the piston discharges combustibles
mechanic action of the exhaust valves.
Four-stroke engine is usually vertical or v-type.
Some four-stroke cross head-type engines were
made many years ago, but four strokes is now manufactured
as a trunk piston type without seal between cylinder
It refers to the internal friction that resists
to the flow of liquid. Theoretically, absolute
viscosity and dynamic viscosity demonstrate the
following correlation :
Dynamic viscosity (absolute viscosity / density)
In general, viscosity refers to Kinematic viscosity
in lubricant, and the unit cSt is used mostly.
Besides the unit of Kinematic viscosity are as
① cSt (Kinematic Viscosity)
The Kinematic viscosity
displayed in the C. G.S units is Stocks and uses
1/100 of it to show Centistoke(cSt).
is 40℃ and 100℃ in accordance with ISO (International
Standard Organization) viscosity classification
is used worldwide.
The outflow time of the
sample fuel of 200cc is divided into ration. The
temperatures measured were 20℃, 50℃, and 100℃,
used by European countries.
③ SUS or SSU(Saybolt Universal Viscosity)
Calculation of the ratio
of the outflow time of the target sample fuel
of 60cc, and the measured temperature are 100℉,
used mostly in the U.S.
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