Crank mechanism for KAMAZ engines 740.11-240, 740.13-260, 740.14-300, 740.11-3902007 RE
The crankshaft is made of high-quality steel and has five main and four connecting rod journals, hardened by HDTV, which are interconnected by cheeks and are mated with transitional fillets
For uniform alternation of working strokes, the location of the connecting rod journals of the crankshaft is made at an angle of 90°.
Two connecting rods are attached to each crankpin: one for the right and one for the left bank of cylinders.
The oil supply to the connecting rod journals is made from the holes in the main journals with straight holes.
To balance the forces of inertia and reduce vibrations, the crankshaft has six counterweights stamped integrally with the cheeks of the crankshaft.
In addition to the main counterweights, there are two additional removable counterweights and pressed onto the shaft, while their angular location relative to the crankshaft is determined by keys.
A ball bearing is pressed into the bore of the crankshaft shank.
A jet 8 is screwed into the cavity of the front toe of the crankshaft. Through the calibrated hole of which the splined power take-off shaft for the fluid coupling drive is lubricated.
The crankshaft is fixed against axial movements by two upper half rings and two lower half rings installed in the grooves of the rear main bearing of the cylinder block, so that the grooved side is adjacent to the thrust ends of the shaft.
An oil pump drive gear and a camshaft drive gear are mounted on the front and rear toes of the crankshaft.
The rear end of the crankshaft has eight threaded holes for the flywheel mounting bolts, the front end of the crankshaft has eight holes for mounting the vibration damper.
The crankshaft is sealed with a rubber cuff 8 (Fig. 3), with an additional sealing element - boot 9.
The seal is located in the flywheel housing 4.
The collar is made of fluoroelastomer using the technology of molding the working sealing lip directly in the mold.
Crankshaft journal diameters:
- - indigenous 95±0.011 mm;
- - connecting rod 80±0.0095 mm.
Eight repair sizes of liners are provided for engine restoration.
Inserts 7405.1005170 Р0. 7405.1005171 Р0. 7405.1005058 P0 are used when restoring the engine without grinding the crankshaft.
If necessary, the crankshaft journals are polished.
Tolerances for the diameters of the crankshaft journals, holes in the cylinder block and holes in the lower head of the connecting rod during engine repairs must be the same as the nominal dimensions of new engines.
The main and connecting rod bearings are made of steel tape coated with a 0.3 mm thick lead bronze layer with a 0.022 mm thick lead-tin alloy layer and a 0.003 mm thick tin layer.
Upper and lower main bearing shells are not interchangeable.
The top liner has a hole for oil supply and a groove for its distribution.
Both bearings of the 4th connecting rod are interchangeable.
From rotation and lateral displacement, the liners are fixed with protrusions (whiskers) included in the grooves provided in the beds of the block, bearing caps and in the beds of the connecting rod.
The bearings have design differences aimed at improving their performance when forcing the engine with a turbocharger, while the marking of the bearings has been changed to 7405.1004058 (connecting rod), 7405.1005170 and 7405.1005171 (main).
Therefore, when carrying out repair maintenance, it is not recommended to replace the liners with serial bearings marked 740.100.., since this will significantly reduce the engine life.
The main bearing caps (Fig. 4) are made of high-strength cast iron grade VCh50.
The covers are fastened with the help of vertical and horizontal coupling bolts 3, 4, 5, which are tightened according to a certain scheme with a regulated moment.
The connecting rod (fig. 5) is steel, forged, the rod I has an I-section.
The upper head of the connecting rod is one-piece, the lower one is made with a straight and flat connector.
The connecting rod is finished assembled with cap 2. therefore, the caps of the connecting rods are not interchangeable.
A steel-bronze bushing 3 is pressed into the upper head of the connecting rod, and replaceable liners 4 are installed into the lower head.
The cover of the lower head of the connecting rod is fastened with nuts 6, screwed onto bolts 5. pre-pressed into the connecting rod.
The connecting rod bolts are tightened according to the scheme.
The cap and connecting rod are marked with mating marks - three-digit serial numbers.
In addition, the cylinder number is stamped on the connecting rod cap.
The flywheel 1 (Fig. 6) is fixed with eight bolts 7 (Fig. 3), made of alloy steel with a dodecahedral head, on the rear end of the crankshaft and is precisely fixed with two pins 10 and an adjusting sleeve 3 (Fig. 6).
In order to prevent damage to the surface of the flywheel, a washer 6 is installed under the bolt heads (Fig. 3).
A ring gear 2 is pressed onto the machined cylindrical surface of the flywheel, with which the starter gear engages when the engine is started (Fig. 6).
When performing adjustment work to set the fuel injection advance angle and the thermal clearances in the valves, the flywheel is fixed with a lock (Fig.7).
At the same time, the design has the following main differences from the serial one:
- - the angle of the slot for the latch on the outer surface of the flywheel has been changed;
- - the diameter of the bore has been increased to accommodate the washer for the flywheel mounting bolts.
The engines under consideration can be equipped with various types of clutches.
In fig. 6 flywheel shows flywheel for diaphragm clutch.
The vibration damper is fixed with eight bolts 2 (Fig. 8) on the front toe of the crankshaft.
In order to prevent damage to the surface of the absorber housing, a washer 5 is installed under the bolts. The absorber consists of a housing (see Figure 7) in which a flywheel is installed with a clearance.
Outside, the damper body is closed with a cover. Tightness is ensured by seaming (welding) at the junction of the damper body and cover.
There is a high-viscosity silicone fluid between the damper body and the flywheel, dosed before the cover is sealed
The absorber is centered with a washer welded to the body (Fig. 8).
The damping of torsional vibrations of the crankshaft occurs by braking the damper housing, mounted 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.
When carrying out repair work, it is strictly forbidden to deform the body and cover of the absorber.
An absorber with a deformed body or cover is not suitable for further use.
Piston 1 (Fig. 9) is cast from an aluminum alloy with an insert made of wear-resistant cast iron under the upper compression ring.
The piston head has a toroidal combustion chamber with a displacer in the central part, it is offset relative to the piston axis by 5 mm away from the grooves for the valves.
The side surface is a complex oval-barrel-shaped shape with an underestimation in the area of the holes for the piston pin.
The skirt is coated with graphite.
A groove is made in its lower part, which, if properly assembled, prevents the piston from contacting the cooling nozzle when it is in the BDC.
The piston is equipped with three rings, two compression and one oil scraper.
Its distinctive feature is the reduced distance from the bottom to the lower end of the upper groove, which is 17 mm.
On engines, in order to ensure fuel efficiency and environmental protection indicators, a selective selection of pistons for each cylinder is applied according to the distance from the axis of the piston pin 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.
Pistons of the greatest height are supplied as spare parts, therefore, in order to avoid possible contact between them and the cylinder heads, in case of replacement, it is necessary to control the over-piston clearance.
If the gap between the piston and the cylinder head after tightening the bolts of its fastening is less than 0.87 mm, it is necessary to cut the piston bottom by the amount missing from this value.
The pistons of engines 740.11, 740.13 and 740.14 differ from each other in the shape of the grooves for the upper compression and oil scraper rings.
Installation of pistons from KAMAZ 740.10 and 7403.10 engines is unacceptable. It is allowed to install pistons with piston rings of engines 740.13 and 740.14 on engine 740.11.
Compression rings (fig. Piston with rings assembled with connecting rod) are made of high-strength, and oil scraper of gray cast iron.
On the 740.11 engine, the cross-sectional shape of the compression rings is a one-sided trapezoid; during installation, the inclined end with the “top” mark must be located on the side of the piston head.
On engines 740.13 and 740.14, the upper compression ring has the shape of a section of a double-sided trapezoid with a recess on the upper end, which should be located on the side of the piston crown.
The working surface of the upper compression ring 4 is covered with molybdenum and has a barrel shape.
Chromium is applied to the working surface of the second compression 5 and oil scraper rings 2. Its shape on the second ring is a cone with a slope towards the lower end, according to this characteristic feature, the ring was called "minute".
Minute rings are used to reduce oil consumption for waste, their installation in the upper groove is not allowed.
Box-type oil scraper ring 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 lock of the ring. On engine model 740.11, the height of the ring is 5 mm, and on engines 740.13 and 740.14, the height of the ring is 4 mm.
Installing piston rings from other models of KAMAZ engines can lead to an increase in oil consumption for waste.
To exclude the possibility of using non-interchangeable parts of the cylinder-piston group during repair work, it is recommended to use repair kits:
- - 7405.1000128-42 - for engine 740.11-240;
- - 740.13.1000128 and 740.30-1000128 - for engines 740.13-260 and 740.14-300.
The repair kit includes:
- - piston;
- - piston rings;
- - piston pin;
- - piston pin circlips
- - cylinder sleeve;
- - O-rings of the cylinder liner.
Cooling nozzles (fig. Installing the sleeve and the piston cooling nozzle) are installed in the crankcase part of the cylinder block and provide oil supply from the main oil line when it reaches a pressure of 0.8 - 1.2 kg/cm2) into the internal cavity of the pistons.
When assembling the engine, it is necessary to control the correct position of the nozzle tube relative to the cylinder liner and piston. Contact with the piston is not allowed.
The piston with the connecting rod (Fig. 9) is connected by a pin 3 of a floating type, its axial movement is limited by retaining rings 6.
The pin is made of chromium-nickel steel, the hole diameter is 22 mm.
The use of pins with a hole of 25 mm is unacceptable, as this disturbs the balance of the engine.
