Man D2862 LE221, Руководство по ремонту

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INTRODUCTION
The engine control units process the information received from the sensors and control the output signals
which are sent to the actuators. The actuators convert the signals into mechanical variables. An actuator is,
for example, the metering unit on the high-pressure pump.
Crankcase
The crankcase consists of the crankcase upper section and the crankcase lower section. Both sections cast
from different special cast irons. The wet cylinder liners made from special, highly wear-resistant centrifugal
casting are exchangeable. The cylinder liners are sealed at the bottom using elastomer sealing rings. At the
rear of the crankcase, there is a ywheel housing. At the front of the crankcase, there is a housing cover.
The ywheel housing and housing cover are made of aluminium. The radial shaft seals are installed in the
housing cover and the ywheel housing.
Positive crankcase ventilation
The crankcase blow-by gases are returned to the combustion air via two oil separators with pressure control
valve on the suction side of the turbochargers.
Crankshaft
The crankshaft is forged in a die using high-quality, micro-alloyed steel. It has 8 mounted counterweights
to balance the masses. The crankshaft is mounted in seven bearings in the crankcase. The crankshaft
journals and connecting rod bearing journals are mounted in ready-to-install three-component bearings. The
axial bearing is provided by thrust bearings in the last bearing seat at the ywheel end. The connecting rod
bearings are supplied with oil via a bore in the crankshaft bearing.
Connecting rods ("cracked" connecting rods)
The "cracked" connecting rods are precision forged in a die using quenched and tempered steel. The large
connecting rod eye is split diagonally by "cracking" the connecting rod bearing cap. The surface structure
resulting from cracking results in a tooth engagement effect between the connecting rod bearing cap and the
connecting rod with a precise, non-interchangeable t and high lateral stability.
Pistons
3-ring steel pistons are used. The pistons have a cooling duct for relieving the thermal load. This area is
covered by exible metal containing a bore into which the oil jet from the oil injection nozzles is injected for
cooling. The ring set comprises one half keystone ring and taper-face ring each as compression rings as
well as a double-bevelled ring as oil scraper ring. The pistons can be removed from above together with the
connecting rods.
Camshaft
The camshaft is forged from steel and is induction hardened. It is mounted in seven bearings in the crankcase.
The camshaft is driven by timing gears that are installed in the ywheel housing.
Cylinder head
The D28 engine is equipped with a camshaft with overhead valves (OHV). Engines in series D28 are equipped
with individual cylinder heads made from special cast iron as well as shrink-tted valve seat rings and
pressed-in exchangeable valve guides. The valve guides have valve stem seals at all four valves. The
cylinder heads are secured with six high-strength external hexagon round bolts (cylinder head bolts). The
single-layer steel cylinder head gasket with elastomer elements has a specially designed combustion chamber
seal.
Engine lubrication
The engine is lubricated by forced-feed lubrication for all bearing points. The engine oil lter and the oil cooler
are grouped together as an oil module. The oil level in the oil sump is measured using a dipstick.
Cooling system
The cooling circuit is a thermostat-controlled forced-circulation cooling system. The maintenance-free coolant
pump is installed on the end face in the housing cover and is driven by a separate gear set. The thermostats
are housed above in the two-section thermostat housing. The thermostats consist of an exchangeable insert
with expansion element.
Intake and exhaust system
The two-piece exhaust manifolds are cast from high temperature-resistant spheroidal graphite cast iron and
are secured on the cylinder heads with heat resistant bolts. Two maintenance-free turbochargers are mounted
on the exhaust manifolds. The turbochargers are lubricated by the engine oil circuit.
20 AE6 3st edition