MAN B&W L32/40 Model

MAN B&W 32/40, L32/40, V32/40, 6L32/40, 7L32/40, 8L32/40, 9L32/40, 12V32/40, 14V32/40, 16V32/40, 18V32/40

General

The engine is a turbocharged, four-stroke diesel engine of the trunk piston type with a cylinder bore of 320 mm and a stroke of 400 mm. The crankshaft
speed is 720/750 rpm. The cylinder output is 500 kW/cyl. and the mean effective pressure is 25.9/24.9 bar.
The engine is delivered as an in-line engine with 6 to 9 cylinders.

Crankcase/Crankshaft bearing/Tie rod

The crankcase of the engine is made of cast iron. It is one-piece and very rigid. Tie rods extend from the lower edge of the suspended main bearing up to the top edge of the crankcase and from the top edge of the cylinder head to the intermediate floor. The bearing caps of the main bearings are also laterally braced with the casing. The control drive and vibration damper housing are integrated in the crankcase.

Coolant/Lubricating oil

The crankcase has no water jackets. The lube oil is delivered to the engine via a distribution pipe which is cast into the housing. The tie rod holes and tie rods have a dual function. They keep components under pre-tension and are also utilised for oil distribution. The sealing of the tie rods takes place at the level of the crankcase intermediate floor.

Accessibility

Engine components are easily accessible through large covers on the long sides. The crankcase covers on the exhaust side are provided with safety valves (generally in the case of marine engines, partly in the case of stationary engines).

Base Frame

The engine and alternator are mounted on a common base frame of a welded steel plate construction. The rigid base frame construction is embedded to the engine seating by means of resilient supports. The inside of the base frame forms a reservoir for the engine lubricating oil.


Bearing cap/Tie rod

The main bearing caps are arranged in a suspended location. They are held in place with tie rods in the base which pass all the way through. Cross-bracing using additional cross tie rods provides structural stability for the bearing body. It prevents lateral displacement of the crankcase under the influence of the ignition pressures.

Locating bearing

The locating bearing, which determines the axial position of the crankshaft, is mounted on the on the first inner bearing seat. It consists of a flange forged onto the crankshaft, the axially arranged thrust collars with AlSn running surface and the accommodating bearing body. The locating bearing flange is supported only in the upper half.

External bearing

The external bearing absorbs radial forces which are transmitted to the crankshaft via the coupling flange. It is formed from the wall of the crankcase, the split bolted-on flange bearing and the labyrinth and spray ring with covering shell.

Bearing shells

The bearing shells of all the main bearings consist of a steel protection shell, a binding layer and an aluminium alloy running layer.

Crankshaft
Crankshaft/Balance weights/Drive gear

The crankshaft is forged from special steel. It is arranged in a suspended manner and has 2 balance weights per cylinder held by extension bolts for further balancing of the oscillating masses. The drive gear for the gear drive consists of 2 segments. They are held together by 4 tangentially arranged bolts. The connection to the locating bearing flange is by head bolts.

Flywheel

The flywheel, made of spheroidal grey cast iron, is arranged on the coupling-side flange on the crankshaft. The engine can be turned over by a turning gear via the flywheel or its toothed ring for maintenance work.


Connecting rod with two section joints

The structure of the connecting rod is made up of the so-called marine head arrangement. The joint gap is above the connecting rod bearing. When retracting the piston the connecting rod bearing need not be split. This has advantages for operational safety (no change in location / no new matching), and this type of structure reduces the piston removal headroom.

Piston
Design characteristics

Basically, the piston consists of two parts. The skirt is made from spheroidal grey cast iron. The piston crown is forged from high-quality materials. Material selection and design effect high resistance levels to the ignition pressures that arise and permit tight piston clearances. Tight piston tolerances and the structure of the piston as a stepped piston reduce the mechanical loading on the piston rings, restrict the access of small particles and protect the oil film from combustion gases.

Cooling

The special shape of the piston rings makes effective cooling more easy. The cooling is supported by the Shaker Effect internally and externally, and by an additional row of cooling holes in the external area. This means that the temperatures are controlled so that wet corrosion in the ring grooves can be prevented. The ring grooves are induction hardened. Subsequent machining is possible.The piston is cooled with oil which is fed through the connecting rod. The oil transfer from the oscillating connecting rod to the piston crown takes place via a spring-loaded funnel which slides on the outer contour of the connecting rod eye.

"Stepped piston"

The piston crown has a slightly smaller diameter than the rest of the running surface. Pistons with this design are referred to as stepped pistons. Explan=ation of the purpose of the stage follow under the point "Cylinder Liner".

Piston rings

The top and bottom sections are connected together with extending bolts. 3 sealing rings and an oil scraping ring are used for sealing the piston to the cylinder liner. The 1st compression ring has a chromium ceramic coating. 2. and 3rd ring are chromium coated. All rings are arranged in the wear-resistant well-cooled steel crown.

Piston pin

The piston pin is supported in a floating manner and axially fixed in position with circlips. Holes, which may influence the formation of oil films and the strength, are not present. 

Cylinder liner/Support ring/Top land ring

The cylinder liners, made of special cast iron, are encased by a spheroidal grey cast iron support ring in the upper section. This is centralised in the crankcase. The lower section of the cylinder liner is guided by the intermediate floor in the crankcase. The so-called top land ring fits on the joint of the cylinder liner. The subdivision into 3 components i.e. the cylinder liner, support ring and top land ring provides the best possible structure with reference to resistance to deformation, with regard to cooling and with regard to ensuring the minimum temperatures on certain component assemblies.

Interaction stepped piston/Top land ring

The top land ring which projects above the cylinder
liner bore works together with the recessed piston
crown of the stepped piston to ensure that burnt
carbon deposits on the piston crown do not come
into contact with the running surface of the cylinder
liner. This prevents bore polishing where lube oil
would not adhere properly.
Cooling

The coolant reaches the cylinder liner via a line that
is connected to the support ring. The coolant flows
through the holes in the top land ring (jet cooling)
and flows through the holes in the support ring to
the cooling chambers in the cylinder heads. The
cylinder head, support ring and top land ring can
be drained together.
The top land ring and cylinder head can be checked
by using check holes in the support ring for gas and
coolant leaks.

Cylinder Head/Rocker Arm Bearing Bracket

The cylinder heads are made from spheroidal grey
cast iron. They are pressed against the top land ring
by 4 studs. The sturdy channel-cooled floor of the
cylinder head and the rib-reinforced inner section
ensure high levels of structural solidity.

The cylinder head has 2 inlet and 2 exhaust valves, 1
starting valve and one each indexing and (on ship's
engines) 1 safety valve. The fuel injection valve is arranged
centrally between the valves. It is surrounded
by sleeves which, in the lower area, are sealed both
against the surrounding coolant chamber and against
the combustion chamber.

Connections

The connections between the cylinder head and the
exhaust pipe, the connections within the charge air
line and with respect to the coolant supply and starting
air line is effected by using quick-fit couplings or
clamping and plug connections.

Rocker arm bearing block/Valve actuation

The cylinder head is closed off from above by a cap,
through which the valves and the injection valve are
easily accessible.

Camshaft and Camshaft Drive

The engine is equipped with two camshafts, which
are driven by a gear wheel of the crankshaft through
intermediate wheels, and rotates with a speed which
is half the speed of the crankshaft.
One camshaft, positioned in control side, only serves
to drive the fuel injection pumps and to operate the
starting air pilot valves, whereas the other arranged
at the exhaust side, operates the inlet and exhaust
valves.

Turbocharger System

The turbocharger system of the engine, which is a
constant pressure system, consists of an exhaust
gas receiver, a turbocharger, a charge air cooler and
a charge air receiver.
The turbine wheel of the turbocharger, which is
of the radial type, is driven by the engine exhaust
gas, and the turbine wheel drives the turbocharger
compressor, which is mounted on one shaft. The
compressor sucks air from the engine room through
the dry air filters.
The turbocharger presses the air through the charge
air cooler to the charge air receiver. From the charge
air receiver, the air flows to each cylinder through
the inlet valves.
The charge air cooler is a compact tube-type cooler
with a large cooling surface.
From the exhaust valves, the exhaust gas is led to
the exhaust gas receiver where the pulsatory pressure
from the individual cylinders is equalized and
passed to the turbocharger as a constant pressure,
and further through the exhaust system and silencer
arrangement.
The exhaust gas receiver is made of pipe sections,
one for each cylinder, connected to each other,
by means of compensators, to prevent excessive
stress in the pipes due to heat expansion. Between
the cylinder head and the exhaust gas line quick
release couplings is mounted, which permits rapid
disconnection.
To avoid excessive thermal loss and to ensure a
reasonably low surface temperature, the exhaust
gas receiver is insulated.

Compressed Air System

The engine is started by means of compressed air
of 30 bar.

Fuel Oil System

The built-on fuel oil system consists of the fuel oil
filter and the fuel injection system.
The fuel oil filter is a duplex filter. The filter is equipped
with a three-way cock for single or double operation
of the filters.
Waste oil and fuel oil leakage is led to a leakage
alarm which is heated by means of fuel returning oil.

Lubricating Oil System

All moving parts of the engine are lubricated with oil
circulating under pressure in a closed built-on system.
The built-on lubricating oil pump is of the gear wheel
type with pressure control valve. The pump takes
the oil from the sump in the base frame, and on the
pressure side the oil passes through the lubricating
oil cooler (plate type) and the filter which both are
mounted on the engine.
Cooling is carried out by the low temperature cooling
water system. The temperature is controlled by
a termostatic 3-way valve on the oil side. The engine
is a standard equipped engine with an electrically
driven prelubricating pump.

Cooling Water System

The cooling water system consists of a low temperature
system and a high temperature system.
The water in the low temperature system is passed
through the charge air cooler (2. stage), the lubricating
oil cooler and the alternator, if the latter is watercooled.
The low temperature media is freshwater.
The high temperature cooling water is passed through
the charge air cooler (1. stage), the engine cylinders
and the cylinder head. The high temperature media
is freshwater.


RI - Retarded Injection

Retarded injection timing delays combustion heat
release and thus lowers combustion chamber temperature
peaks.

Device for variable injection timing (V.I.T.)

The V.I.T. is designed to influence injection timing and
thus ignition pressure and combustion temperature.
That enables engine operation in different load ranges
well balanced between low NOx emissions and low
fuel consumption.

New piston for increased compression ratio

The use of a new piston provides a higher compression
ratio and gives a faster reduction in temperature
after the ignition of the fuel, thus reducing NOx
formation. The increase in compression ratio also
compensates the reduction in firing temperature
due to retarded injection and hence the associated
increase in SFOC.

Miller valve timing

To reduce the temperature peaks which promote
the formation of NOx, early closure of the inlet valve
causes the charge air to expand and cool before start
of compression. The resulting reduction in combustion
temperature reduces NOx emissions.