The cylinder block is the main body part of the engine and is a casting of vermicular graphite iron
The casting is subjected to artificial aging to relieve thermal stresses, which allows the block to maintain the correct geometric shapes and dimensions during operation.
Two rows of semi-blocks for cylinder liners, cast as one piece with the upper part of the crankcase, are located at an angle of 90° to each other.
The left row of bores for the sleeves is shifted relative to the right one forward (toward the fan) by 29.5 mm, due to the installation of two connecting rods on each crankpin of the crankshaft.
Each bore has two coaxial cylindrical holes made in the upper and lower zones of the block, along which the cylinder liners are centered, and undercuts in the upper zone, forming annular platforms for the shoulders of the liners.
In order to ensure the correct fit of the sleeve in the block, the parameters of flatness and perpendicularity of the thrust pad under the shoulder of the sleeve relative to the axis of the centering bores are performed with high accuracy.
There are two grooves for O-rings on the lower belt, which prevent the coolant from getting from the cooling cavity of the block into the cavity of the engine oil crankcase.
The bosses of the holes for the cylinder head bolts are made in the form of lugs to the transverse walls forming the cooling jacket, evenly distributed around each cylinder.
The crankcase part of the block is connected to the main bearing caps with main and tie bolts.
The main bearing caps are centered with horizontal pins 8 (Figure 1), which are pressed at the junction between the block and the caps, but mostly included in the block to prevent them from falling out when the caps are removed.
In addition, the cover of the fifth main bearing is centered in the longitudinal direction by two vertical pins, which ensure the accuracy of matching the bores for the crankshaft thrust half rings on the block and on the covers.
The order of tightening the bolts for fixing the covers of the main bearings in accordance with the article Tightening torques for KAMAZ diesel connections.
The bore of the cylinder block for the main bearing shells is assembled with covers, so the main bearing caps are not interchangeable and are installed in a strictly defined position.
Each cover is marked with the serial number of the support, the numbering of which starts from the front end of the block.
In the crankcase part of the collapse of the cylinder block, guides of the valve lifters are made in the form of bosses.
Closer to the rear end between the fourth and eighth cylinders, to improve the circulation of the coolant, a bypass pipe of the cooling cavity is made.
At the same time, it also gives the block additional rigidity.
Parallel to the axis of the bores for the crankshaft bearings, bores are made for the camshaft bushings of increased dimension.
The diameters of the oil channels in the cylinder block are increased.
In the lower part of the cylinders, together with the block, bosses for piston cooling nozzles are cast.
In order to install on the filter unit with a heat exchanger on the right side, compared to the 740.10 engine, the platform for the filter has been increased, two additional mounting holes and a drain hole from the filter have been introduced.
During the transitional period of mastering production, as part of the 740.30-260 engine, a cylinder block with modified screw-on pusher guides, with oversized camshaft bushings, without enlarged oil channels, without fixing the main bearing caps on horizontal pins can be used.
The tightening torques of the mounting bolts are 73.5 ... 93 Nm (7.5 ... 9.5 kgf m).
Cylinder liners (picture 2) of a "wet" type, easily removable, are marked 7406 on the conical part at the bottom of the sleeve.
The cylinder liner is made of gray special cast iron hardened by volumetric hardening and differs in the size of the tempering zone from the heat treatment of liners that do not have this marking.
Installing liners without the indicated marking on the engine 740.30-260 leads to accelerated wear of liners and piston rings.
In the liner - cylinder block connection, the cooling cavity is sealed with rubber O-rings.
In the upper part there is a ring 5 in the groove of the sleeve, in the lower part there are two rings 4 in the bores of the cylinder block.
The microrelief on the mirror of the sleeve is a rare network of depressions and areas with small risks at an angle to the axis of the sleeve.
When working engine oil is retained in the depressions, which improves the running-in of parts of the cylinder-piston group.
When assembling the engine, the number of the cylinder and the index of the piston version are applied on the non-working protrusion of the end of the sleeve.
The drive of the units (Figure 3) is carried out by spur gears and serves to drive the gas distribution mechanism, the high-pressure fuel pump, the compressor and the power steering pump of the car.
The gas distribution mechanism is actuated from gear 10, mounted at the end of the crankshaft, through a block of intermediate gears that rotate on two rows of rollers 3, separated by an intermediate sleeve 4 and located on axis 1, fixed on the rear end of the cylinder block.
A gear wheel 15 is pressed onto the end of the camshaft, the angular location of which relative to the shaft cams is determined by a key.
The gear wheel 15 of the drive of the high pressure fuel pump (TNVD) is mounted on the shaft 13 of the injection pump drive and is fixed with the key 14.
The gears are mounted on the engine in a strictly defined position according to the “O” mark on the camshaft drive gear, the “E” mark on the injection pump drive gear and the risks knocked out on the gears, as shown in Figure 3.
The injection pump is driven by gear wheel 15, which is engaged with the gear wheel of the camshaft 15.
The rotation from the shaft to the injection pump is transmitted through the driving and driven coupling halves with elastic plates, which compensate for the misalignment of the installation of the injection pump shafts and the gear wheel.
The gears of the compressor and power steering pump are engaged with the gear wheel of the injection pump drive.
The crankcase is attached to the rear end of the cylinder block.
In the upper part of the crankcase of the units there are bores into which the compressor and power steering pump are installed.
On the sides of the crankcase of the units there are bosses with holes for draining oil from turbochargers and a hole for the oil level indicator.
The drive of the units is closed by the flywheel housing, fixed to the rear end of the cylinder block through the housing of the units.
On the flywheel housing on the right there is a place for installing a flywheel lock, used to set the fuel injection advance angle and regulate thermal gaps in the gas distribution mechanism.
The lock knob must be in the up position when the engine is running.
It is transferred to the lower position during adjustment work, in this case the latch is engaged with the flywheel.
A bore is made in the upper part of the flywheel housing, into which the rear bearing housing is installed.
There is a bore at the bottom left of the crankcase where the starter is installed.
In the middle of the crankcase, a bore was made for the crankshaft collar.
A tide is made in the upper part of the crankcase on the left, designed to install a power take-off (PTO). In the absence of a CTO, the inner surfaces of the tide are not processed.
The rear flange of the flywheel housing is made with connecting dimensions according to SAE1.