892-0000010B OM
75
Cylinder block 11 is the main body part of the engine and is a rigid pig iron casting.
Four removable liners 8 are installed in the vertical bores of the block. The liner is installed
in the cylinder block along two centering belts: upper and lower. In the upper belt, the liner
is fixed by a collar, in the lower belt it is sealed with two rubber rings placed in the grooves
of the cylinder block. Coolant circulates between the walls of the cylinder block and the
liners. The end walls and transverse partitions of the cylinder block have bosses designed
to form crankshaft supports. Covers are installed on these bosses. The bosses, together
with the covers, form seats for the main bearings. The seats for the inserts of the main
bearings are bored out within a single installation, complete with the main bearing caps.
Swapping the covers is not allowed.
The cylinder block has a longitudinal channel, from which oil flows through the trans-
verse channels to the crankshaft main bearings and camshaft bearings. The cylinder block
of the D-245.5 engine in the second and fourth upper supports of the crankshaft has nozzles
that serve to cool the pistons with an oil jet.
On the outer surfaces of the cylinder block, there are machined mating surfaces for
attaching a centrifugal oil filter, a water pump, coarse and fine fuel filters, and an oil filler
neck.
The main parts of the crank mechanism are: crankshaft 14, pistons 7 with piston rings
and pins 4, connecting rods 5, main and connecting rod bearings, flywheel 12.
Crankshaft 14 is made of steel, has five main and four connecting rod journals. There
are cavities in the connecting rod journals of the crankshaft for additional centrifugal oil
cleaning. The cavities of the journals are closed with threaded plugs. The axial strain of the
crankshaft is perceived by four half rings installed in the bores of the cylinder block and the
cover of the fifth main bearing. To reduce the loads on the bearings from inertial forces,
counterweights 13 are installed on the first, fourth, fifth and eighth webs of the crankshaft.
Front and rear, the crankshaft is sealed with seals. A timing gear (crankshaft gear), an oil
pump drive gear, a water pump and alternator drive pulley are installed on the front end of
the shaft. Flywheel 12 is attached to the rear flange of the shaft.
Piston 7 is made of aluminum alloy. A combustion chamber is made in the bottom of
the piston. In the upper part, the piston has three grooves - compression rings are installed
in the first two, and an oil scraper ring in the third. An insert made of special cast iron is
poured into the groove for the upper compression ring in the trapezoidal form. Holes for the
piston pin are bored in the piston bosses.
Piston pin 4 is hollow, made of chromium-nickel steel. The axial movement of the pin
in the piston bosses is limited by the circlips.
Connecting rod 5 is steel, I-section. A sleeve is press-fitted into its upper head. For
lubrication of the piston pin, there are holes in the upper head of the connecting rod and the
bushing. The boring of the seat in the lower head of the connecting rod for the inserts is is
carried out in assembly with the cover. Therefore, changing the connecting rod caps is not
allowed. The connecting rod and cap have the same numbers stamped on their surfaces.
Flywheel 12 is made of cast iron, bolted to the crankshaft flange. A steel ring gear is
pressed onto the flywheel.
The timing mechanism consists of a camshaft, intake and exhaust valves, as well as
parts for their installation and a drive: pushers, rods, rocker arms, adjusting screws with nuts,
discs with cotters, springs, rocker shanks and shafts.
The engine fuel supply system, in accordance with Figure 3.1.2, consists of fuel pump
4, injectors 14, low and high pressure pipelines, air cleaner 8, intake and exhaust manifolds,
coarse 2 and fine fuel filters 7, fuel tank 1 mounted on the tractor. The fuel supply system
includes turbocharger 17.
The turbocharger uses energy of exhaust gases to pressurize air into the engine cylin-
ders. The principle of operation of the turbocharger is that the exhaust gases from the engine
cylinders enter through the exhaust manifold into the scroll channels of the turbine under pres-
sure. Expanding, the gases rotate the rotor, the compressor wheel of which sucks in air
through the air cleaner and supplies it under pressure to the engine cylinders. The rotor speed,
delivery and pressure of the injected air depend on the operating mode of the engine. The
turbocharger bearings are lubricated and cooled by oil coming through the pipeline from the
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