The crankshaft (Figure 1) is made of high-quality steel and has five main and four connecting rod journals, connected by cheeks and mated with transition fillets
For uniform alternation of working strokes, the connecting rod journals of the crankshaft are located at an angle of 90°.
Fig. 1. Crankshaft: 1 - counterweight; 2, 3 - oil pump drive gear; 4 - plug; 5 - key; 6 - relief holes; 7 - oil supply holes to the connecting rod journals; 8 - oil supply holes in the main journals
Two connecting rods are attached to each connecting rod journal (Figure 2) - one for the right and one for the left rows of cylinders.
Fig. 2. Connecting rod: 1 - connecting rod rod; 2 - connecting rod cap; 3 - connecting rod upper head bushing; 4 - connecting rod lower head liner; 5 - connecting rod cap fastening bolt; 6 - connecting rod cap fastening nut
The crankshaft is hardened by nitriding to a depth of 0.5-0.7 mm, the hardness of the hardened layer is not less than 600 HV.
Oil is supplied to the connecting rod journals through holes in the main journals 6 and holes 5 (Figure 1).
To balance the inertial forces and reduce vibrations, the crankshaft has six counterweights stamped together with the crankshaft cheeks.
In addition to the main counterweights, there is an additional removable counterweight 1, pressed onto the shaft, its angular position relative to the crankshaft is determined by key 4.
To ensure the required imbalance, a recess 6 is made on the flywheel (Figure 5).
A neck 9 is made on the crankshaft tailstock (Figure 3), along which the crankshaft gear 8 and flywheel 1 (Figure 6) are centered.
Ten threaded holes M16x1.5-6H are made on the rear end of the crankshaft for fastening the crankshaft gear and flywheel, eight threaded holes M 12x1.25-6H are made on the front end for fastening the torsional vibration damper.
A plug 3 (Figure 1) is installed in the cavity of the crankshaft nose, through the calibrated hole of which the splined shaft of the front power take-off drive is lubricated.
The crankshaft is fixed from axial movements by two upper half rings 1 and two lower half rings 2 (Figure 3), installed in the grooves of the rear main bearing of the cylinder block, so that the side with the grooves adjoins the thrust ends shaft.
The gears of the oil pump drive 2 and the timing gear drive 8 (Figure 3) are mounted on the nose of the crankshaft (Figure 1).
The crankshaft is sealed by a rubber cuff 8 (Figure 6), with an additional sealing element - a boot 9. The cuff is located in the flywheel housing 4.
The cuff is made of fluororubber using the technology of forming the working sealing edge directly in the mold.
Nominal diameters of the crankshaft journals:
- - main 95-0.015 mm;
- - connecting rod 80-0.013 mm.
Eight repair sizes of liners.
The designation of the crankshaft bearing liners, the diameter of the crankshaft main journals, the diameter of the hole in the cylinder block for these liners are listed in Table 1
The designation of the lower connecting rod head liners, the diameter of the crankshaft connecting rod journals, the diameter of the hole in the crank head of the connecting rod for these liners are listed in Table 2.
Bearings 7405.1005170 P0, 7405.1005171 P0, 7405.1005058 P0 are used when rebuilding an engine without grinding the crankshaft. If necessary, polish the crankshaft journals.
When grinding the crankshaft on the main journals up to 94 mm or less or on the connecting rod journals up to 79 mm or less, it is necessary to subject the crankshaft to repeated nitriding.
The tolerance limits for the crankshaft journal diameters, the bore diameter in the cylinder block and the bore diameter in the connecting rod crank head when rebuilding the engine must be the same as for the nominal dimensions.
The crankshaft for engines 740.50-360 and 740.51-320 has significant differences from the crankshafts of other engine models, these differences make it impossible to use crankshafts of KAMAZ engines of other models.
The crankshaft marking made in the forging on the third counterweight must be 740.50-1005020.
Fig. 3. Installing the thrust half rings and liners of the crankshaft: 1 - upper thrust bearing half ring; 2 - lower thrust bearing half ring; 3 - upper crankshaft bearing shell; 4 - lower crankshaft bearing shell; 5 - cylinder block; 6 - rear crankshaft bearing cap; 7 - crankshaft; 8 - timing gear; 9 - crankshaft centering journal
The main and connecting rod bearings (Figures 2 and 3) are made of steel tape coated with a 0.3 mm thick layer of lead bronze, a 0.022 mm thick layer of lead-tin alloy and a 0.003 mm thick layer of tin.
The upper 3 and lower 4 main bearing shells are not interchangeable. The upper bearing has a hole for supplying oil and a groove for distributing it.
Both bearings 4 of the lower connecting rod head are interchangeable.
The bearings are secured from turning and lateral displacement by projections (whiskers) that enter the grooves provided in the block and connecting rod beds, as well as the bearing caps.
The bearings have design differences aimed at increasing their performance when forcing the engine with turbocharging, while the marking of the bearings has been changed to 7405.1004058 (connecting rod), 7405.1005170 and 7405.1005171 (main).
It is not recommended to replace the bearings during repairs with serial ones marked 740, since this will significantly reduce the engine life.
Fig. 4. Installing the crankshaft bearing caps: 1 - bearing cap; 2 - crankshaft; 3 - cover fastening bolt; 4 - left bearing cap tightening bolt; 5 - right bearing cap tightening bolt; 6 - washer; 7 - block; 8 - pin
The main bearing caps (Figure 4) are made of high-strength cast iron.
The caps are fastened with vertical and horizontal tie bolts 3,4,5, which are tightened according to a specific pattern with a specified torque. Tightening torques for fasteners of the KAMAZ diesel engine 740.11-240, 740.13-260, 740.14-300, 740.30-260, 740.50-360, 740.51-320
The connecting rod (Figure 2) is steel, forged, rod I has an I-section. The upper connecting rod head is non-separable, the lower one is made with a straight and flat connector.
The connecting rod is finally machined together with the cover 2, therefore the connecting rod covers are not interchangeable.
A steel-bronze bushing 3 is pressed into the upper connecting rod head, and replaceable liners 4 are installed in the lower one.
The cover of the lower connecting rod head is fastened with nuts 6 screwed onto bolts 5, pre-pressed into the connecting rod rod.
The connecting rod bolts are tightened according to the scheme defined in Tightening torques for fasteners of the KAMAZ diesel engine 740.11-240, 740.13-260, 740.14-300, 740.30-260, 740.50-360, 740.51-320
The connecting rod cap and rod are marked with pairing marks - three-digit serial numbers. In addition,
the cylinder serial number is stamped on the connecting rod cap.
Fig. 5. Flywheel: 1 - ring; 2 - spacer sleeve; 3 - flywheel toothed rim; 4 - mounting pin; 5 - bearing; 6 - sample for imbalance
Flywheel (Figure 5) is secured with ten bolts 7 (Figure 6), made of alloy steel, on the rear end of the crankshaft and fixed with pin 10 (Figure 6) on the centering journal of the crankshaft 9 (Figure 3).
In order to prevent damage to the flywheel surface, a washer 6 (Figure 6) is installed under the bolt heads.
The value of the tightening torque of the flywheel mounting bolts is specified in the article Tightening torques for KAMAZ diesel engine fasteners
A toothed rim 3 (Figure 5) is pressed onto the machined cylindrical surface of the flywheel, with which the starter gear engages when starting the engine.
Under the seal cuff crankshaft, ring 1 with an outer chromed surface is installed.
Fig. 6. Installing the flywheel: 1 - ma Hovik; 2 - cylinder block; 3 - crankshaft; 4 - flywheel housing; 5 - gearbox input shaft bearing; 6 - washer; 7 - bolt; 8 - crankshaft seal cuff; 9 - seal boot; 10 - flywheel mounting pin
The flywheel is made for one or two-disc diaphragm clutches.
Bearing 5 of the primary shaft of the gearbox is installed in the inner bore of the flywheel.
Fig. 7. Positions of the flywheel lock handle: a) - during operation; b) - when adjusting in engagement with the flywheel
When adjusting the fuel injection advance angle and thermal clearances in the valves, the flywheel is fixed with a lock (Figure 7).
The flywheel design has the following main differences from the flywheels of the 740.10 and 7403.10 engines:
- - the angle of the groove for the lock on the outer surface of the flywheel has been changed;
- - the diameter of the bore to accommodate the washer for the flywheel mounting bolts has been increased;
- - a sickle-shaped sample has been introduced to ensure the required imbalance;
- - the flywheel is fastened to the end of the crankshaft with ten M16x1.5 bolts;
The listed changes make it impossible to install flywheels of engines of other models during repair work.
Fig. 8. Crankshaft vibration damper: 1 - damper housing; 2 - damper cover; 3 - centering washer; 4 - filler plug; 5 - damper flywheel; 6 - silicone fluid
The torsional vibration damper (Figure 8) is secured with eight bolts 2 (Figure 9) on the front nose of the crankshaft.
Fig. 9. Installing the crankshaft torsional vibration damper: 1 - damper; 2 - damper mounting bolt; 3 - fluid take-off half coupling; 4 - half coupling mounting bolt; 5 - washer; 6 - crankshaft; 7 - cylinder block
The damper consists of a housing 1 (Figure 8) in which the damper flywheel 2 is installed with a gap. The damper housing is closed from the outside by a cover 3. Tightness is ensured by welding along the joint of the damper housing and the cover.
Between the damper housing and the damper flywheel there is a high-viscosity silicone fluid, dosed before welding the cover. The damper is centered by a washer 6 welded to the housing.
Damping of torsional vibrations of the crankshaft occurs by braking the damper housing, fixed on the toe of the crankshaft, relative to the flywheel in a silicone fluid environment. In this case, the braking energy is released in the form of heat.
During repair work, it is prohibited to deform the damper housing and cover. A damper with a deformed body or cover is not suitable for further operation.
After installing the damper, check for a gap between the damper and the counterweight.
Fig. 10. Piston with connecting rod and rings assembled: 1 - piston; 2 - oil scraper ring; 3 - piston pin; 4, 5 - compression rings; 6 - retaining ring
Piston 1 (Figure 10) is cast from an aluminum alloy with a wear-resistant cast iron insert under the upper compression ring.
The piston head has a toroidal combustion chamber with a displacer in the central part, which is offset relative to the piston axis away from the recesses for the valves by 5 mm.
The side surface is a complex oval-barrel shape with a lowering in the area of the holes for the piston pin. The skirt is coated with graphite.
A groove is made in the lower part of the piston skirt, which eliminates, if assembled correctly, contact of the piston with the cooling nozzle when it is at the bottom dead center.
The piston is equipped with two compression rings and one oil scraper ring.
Its distinctive feature is the reduced distance from the bottom to the lower end of the upper groove, which is 17 mm.
Similarly to other KAMAZ engine models, the engine uses selective selection of pistons for each cylinder by the distance from the piston pin axis to the bottom.
According to the specified parameter, the pistons are divided into four groups: 10, 20, 30 and 40. Each subsequent group differs from the previous one by 0.11 mm.
The pistons of the greatest height are supplied as spare parts - for engines 740.50-360 and 740.51-320, the size from the piston pin axis to the bottom of the piston of group 40 (the greatest) is 71.04-0.04 mm.
To avoid possible contact between them and the cylinder heads, in case of replacement, it is necessary to control the above-piston clearance.
If the clearance between the piston and the cylinder head after tightening the bolts of its fastening is less than 0.87 mm, it is necessary to trim the piston bottom by the missing this value.
Installation of pistons from KAMAZ engines of other models is not allowed. Piston marking 740.51-1004015 is made in casting on the inner cavity of the piston.
Compression rings (Figure 10) are made of high-strength cast iron, and the oil scraper ring is made of gray cast iron.
The upper compression ring has the shape of a double-sided trapezoid, with an internal groove on the upper end, and the second has the shape of a single-sided trapezoid.
During installation, the end with the "top" mark should be located on the piston bottom side.
The working surface of the upper compression ring 4 is coated with molybdenum and has a barrel shape.
Chrome is applied to the working surface of the second compression ring 5 and oil scraper ring 2.
Its shape on the second ring is a cone with a slope towards the lower end, according to this characteristic The ring is called "minute" for this reason.
Minute rings are used to reduce oil consumption due to waste; their installation in the upper groove is unacceptable.
Box-type oil scraper ring, 4 mm high, with a spring expander having a variable pitch of turns and a ground outer surface.
The middle part of the expander with a smaller pitch of turns when installed on the piston should be located in the ring lock.
Installation of piston rings from other KAMAZ engine models can lead to an increase in oil consumption due to waste and, as a consequence, to a deterioration in environmental performance.
Cylinder liner with piston cooling nozzle: 1 - nozzle tube; 2 - piston cooling nozzle valve assembly; 3 - sealing gasket; 4 - lower liner sealing ring; 5 - upper sealing ring; 6 - cylinder liner; 7 - crankcase
The cooling nozzles (Figure 6) are installed in the crankcase part of the cylinder block and supply oil from the main oil line, when the pressure in it reaches 80-120 kPa (0.8-1.2 kg/cm²), to the inner cavity of the pistons.
The valve located in each of the nozzles is adjusted to this pressure.
When assembling the engine, it is necessary to check the correct position of the nozzle tube relative to the cylinder liner and piston. Contact with the piston is unacceptable.
The piston with the connecting rod (Figure 10) is connected by a floating pin 3, its axial movement is limited by retaining rings 6.
The pin is made of chromium-nickel steel, the hole diameter is 16 mm. The use of pins with a hole diameter of 22 and 25 mm is unacceptable, since this disrupts the engine balance.
Fig. 11. Installing the front power take-off drive and pulley: 1 - accessory drive shaft; 2 - power take-off half coupling; 3 - power take-off shaft; 4 - pulley; 5 - bolt; 6 - upper block cover; 7 - bearing housing; 8 - cuff; 9 - spring; 10 - plug; 11, 12 - bearings; 13 - crankshaft
The front power take-off drive (Figure 11) is carried out from the nose of the crankshaft through the power take-off half-coupling 2, attached to the nose of the crankshaft 13 with eight special bolts Ml2x1.25.
The centering of the half-coupling relative to the crankshaft is carried out by the internal bore of the external counterweight.
The torque from the half-coupling is transmitted by means of the drive shaft of the units 1 and the power take-off shaft 3 to the pulley 4.
The power take-off shaft 3 is mounted on two ball bearings 11 and 12.
The cavity is sealed with a cuff 8 and a plug 10 with a rubber ring 14. To reduce wear of the splined joints, the drive shaft of the units is held from axial movements spring 9.
