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Pic. 5: 1. Pulley nut. 2. Generator drive pulley and coolant pump. 3. The axis of the tension roller. 4. Tension roller. 5. Camshaft pulley. 6. Camshaft seal. 7. Gland holder. 8. Thrust flange of the camshaft. 9. Camshaft bearing housing. 10. Camshaft. 11. Thermoregulating piston plate. 12. Piston. 13. Top compression ring. 14. Lower compression ring. 15. Oil scraper ring. 16. Piston pin. 17. A bolt of fastening of a cover of a rod. 18. Flywheel. 19. Thrust semi-ring of the crankshaft. 20. Front bearing of the input shaft of the gearbox. 21. Flywheel toothed rim. 22. Inserts 3rd (central) crankshaft main bearing. 23. Inserts 1, 2, 4 and 5 of the main bearings of the crankshaft. 24. Crankshaft. 25. Inlet valve. 26. Valve guide. 27. Retaining ring. 28. Exhaust valve. 29. Toothed pulley of the crankshaft. 30. Toothed belt. 31. Oil cap. 32. Oil pump drive pulley, ignition distributor and fuel pump. 33. Tension roller bracket. 34. Tension roller spring. 35. External valve spring. 36. Spring plate. 37. Valve crackers. 38. Valve drive lever. 39. Lever spring. 40. Lever spring retainer plate 41. Insert and connecting rod. 42. Connecting rod cover. 43. Connecting rod. 44. Valve adjusting bolt. 45. Internal valve spring. 46. Support washer of the inner spring 47. Support washer of the outer spring. 48. Tags w.m.t. pistons of the 1st and 4th cylinders.
The energy of the expansion of the products of combustion of fuel through the crank mechanism of the engine is transmitted to the crankshaft of the engine. The details of the crank mechanism are exposed to significant mechanical and thermal loads. The selection of materials for the piston, pin, piston rings and their design provide reliable cylinder sealing, efficient heat dissipation, low weight of parts, minimum friction coefficient, high strength and reliability.
pistons 12 are made of aluminum alloy and coated with a layer of tin to improve run-in. The piston skirt is oval in cross section, and the major axis of the oval is perpendicular to the axis of the piston pin. The piston has a conical shape in height: the diameter is smaller at the top than at the bottom. In addition, steel thermostatic plates 11 are poured into the piston bosses. All this is done to compensate for the uneven thermal deformation of the piston during operation in the engine cylinders, which occurs due to the uneven distribution of the metal mass inside the piston skirt.
The piston bosses have holes for the passage of oil to the piston pin. The hole for the piston pin is offset from the axis of symmetry by 2 mm to the right side of the engine. This reduces the possibility of piston knocking when going through the c. m. t. For the correct installation of the piston in the cylinder, there is a mark near the hole for the piston pin "P". The piston must be installed in the cylinder with the mark facing the front of the engine.
Pistons, like cylinders, are subdivided into five classes according to the outer diameter through 0.01 mm, denoted by the letters A, B, C, D, E. The following cylinder diameters correspond to them, in mm:
- A - 78.94-78.95
- B - 78.95-78.96
- C - 78.96-78.97
- D — 78,97-78,98
- E - 78.98-78.99
Due to the complex shape of the outer surface of the piston, it is necessary to measure its diameter in a plane perpendicular to the axis of the piston pin and at a distance of 52.4 mm from the piston crown.
Pistons of classes A, C, E are supplied as spare parts. These classes are sufficient for selecting a piston for any cylinder, since pistons and cylinders are divided into classes with some overlap in size. For example, to cylinders of classes View) a class C piston may fit. In addition, when repairing engines, pistons are usually replaced for worn cylinders, therefore, a class C piston may fit a slightly worn cylinder that had a class B. The main thing when choosing a piston is to ensure the necessary mounting clearance between the piston and the cylinder (0.05-0.07mm).
According to the diameter of the hole for the piston pin, the pistons are subdivided through 0.0 () 4 mm into three categories, indicated by the numbers 1, 2, 3. Piston class (letter) and piston pin bore category (number) stamped on the bottom of the piston.
Pistons by weight in the same engine are selected with a maximum allowable deviation of±2.5 g.
Piston pin 16 steel, cemented, tubular section, pressed into the upper head of the connecting rod with an interference fit and rotates freely in the piston bosses.
Piston pins, like the holes in the piston bosses, are divided into three categories according to the outer diameter through 0.004 mm. The category of the finger is marked on its end with the corresponding color: the first category is blue, the second is green, and the third is red. The pin and piston to be assembled must belong to the same category.
Piston rings 13, 14, 15, which provide the necessary sealing of the cylinder, are made of cast iron. The piston has two compression (sealing) rings that seal the gap between the piston and cylinder and remove heat from the piston, and one oil scraper, which prevents oil from entering the combustion chamber. The rings are pressed against the cylinder wall by their own elasticity and gas pressure.
The upper compression ring 13 operates under conditions of high temperature, aggressive effects of combustion products and insufficient lubrication, therefore, to increase wear resistance, its outer surface is chrome-plated and has a barrel-shaped generatrix to improve running-in.
Bottom compression ring 14 scraper type (has a groove on the outer surface), phosphated, also performs the additional function of an oil-drop ring. The ring must be installed with the groove down, otherwise oil consumption and carbon formation in the combustion chamber increase. The oil scraper ring 15 has slots for the oil removed from the cylinder and an internal twisted spring - an expander that provides additional pressing of the ring against the cylinder wall.
Connecting rods 43 - steel, forged with an I-section rod. The lower head of the connecting rod is detachable; inserts 41 of the connecting rod bearing are installed in it. The cover 42 of the lower head is fastened with two bolts 17 and self-locking nuts. The connecting rod is processed together with the cover, and therefore, during assembly, the existing numbers on the connecting rod and the cover must be the same and be on the same side. Oil passes through the hole located at the transition point of the lower head of the connecting rod to the rod, lubricating the cylinder walls.
The assembly of the connecting rod with the piston is carried out so that the mark "P" on the piston was on the output side of the oil hole on the lower head of the connecting rod, if it has one.
The crankshaft 24 is cast iron and is the main power part of the engine, which perceives the action of gas pressure and inertial forces. The shaft material works for fatigue. An increase in fatigue strength is achieved by a large overlap of the main and connecting rod journals, the presence of five bearings (full support), surface hardening of the necks with high-frequency currents to a depth of 2-3 mm, specially made smooth transitions between the necks and cheeks, careful processing of stressed areas.
Lubrication from the main bearings to the connecting rods is supplied through drilled channels, which are closed with cap plugs. At the rear end of the crankshaft there is a socket for the front bearing 20 of the primary shaft of the gearbox. The flywheel 18 is cast iron and has a pressed steel gear rim 21 for starting the engine with a starter. The flywheel is attached to the rear end of the crankshaft with six bolts, under which a common steel washer is installed. The flywheel is centered on the outer diameter of the bearing 20 of the gearbox input shaft.
The flywheel is mounted on the crankshaft so that mark A (cone-shaped hole near the gear rim of the flywheel) and the axis of the connecting rod journal of the first cylinder were in the same plane and on one side of the axis of the crankshaft.
The liners of the main 22, 23 and connecting rod 41 bearings are thin-walled, bimetallic steel-aluminum. The shells of each main or connecting rod bearing consist of two halves. The bearings are kept from turning by a protrusion that enters the groove of the connecting rod or main bearing, all connecting rod bearings are the same and interchangeable. The shells 23 of the first, second, fourth and fifth main bearings are the same and interchangeable, have a groove on the inner surface (since 1987 the lower shells of these bearings have been installed without a groove). Insert 22 third (central) the main bearing differs from the rest in width and the absence of a groove on the inner surface. The gas distribution mechanism ensures that the engine cylinders are filled with a fresh charge of the combustible mixture and the exhaust gases are released.
The details of the gas distribution mechanism include: a camshaft, valves and guide bushings, springs with fasteners, valve drive levers, the gas distribution mechanism is driven from the drive pulley 29 of the crankshaft by a toothed belt 30. The same belt drives the drive shaft through another pulley 32 oil pump, ignition distributor and fuel pump.
The camshaft 10, which controls the opening and closing of the valves, is cast iron, cast, with high-frequency hardened rubbing surfaces of the cams. From 1982 to 1984, along with the production of levers 38 from 40X steel, the camshafts were nitrided for increased wear resistance instead of hardening with high frequency currents. As a result of saturation of the metal surface with nitrogen and partially with carbon, a hardened layer is obtained, which provides increased corrosion resistance, wear resistance, and high resistance to alternating loads. The hardened layer consists of a zone of chemical compounds of the Fe2N type with a thickness of up to 20 μm and a diffusion zone of a solid solution of nitrogen and carbon α-Fe with a depth of up to 0.5 mm.
Since 1985, camshafts with camshafts have been installed. These shafts have a distinctive hex collar between the 3rd and 4th jaws. The bleaching process consists in electric arc melting of surfaces, as a result of which a layer of the so-called "white" cast iron with high hardness.
A driven pulley 5 is attached to the front end of the camshaft with a central bolt. The camshaft rotates on five bearings in a special housing 9, mounted on the cylinder head at nine points.
The camshaft is held from axial movements by a thrust flange 8, placed in the groove of the front support neck of the shaft, the thrust flange is attached to the camshaft bearing housing with two studs and nuts. Lubrication to the rubbing surfaces of the camshaft under; It is led from the oil line through a groove on the central bearing journal, through drilling along the shaft axis and holes on the cams and bearing journals.
valves (intake 25 and exhaust 28), which serve to periodically open and close the openings of the intake and exhaust channels, are located in the cylinder head obliquely in one row. The intake valve head has a larger diameter for better cylinder filling, and the exhaust valve face, which operates at high temperatures in an aggressive exhaust gas environment, has a heat-resistant alloy overlay.
In addition, the exhaust valve is made of composite: the stem is made of chromium-nickel-molybdenum steel with better wear resistance to friction and thermal conductivity to remove heat from the valve head to its guide sleeve, and the head is made of heat-resistant chromium-nickel-manganese steel. The inlet valve is made of chromium-nickel-molybdenum steel.
Springs (outer 35 and inner 45) press the valve to the seat and do not allow it to come off the actuator lever. The lower ends of the springs rest on two support washers 46 and 47. The upper support plate 36 of the springs is held on the valve stem by two crackers 37, which, when folded, have the shape of a truncated cone.
Valve guide bushings 26 are made of cast iron, pressed into the cylinder head and are held from possible loss by retaining rings 27. The hole in the bushing is finished assembled with the cylinder head, which ensures a narrow tolerance on the diameter of the hole and the accuracy of its location in relation to the working chamfers of the seat and valve. To reduce the penetration of oil into the combustion chamber through the gaps between the sleeve and the valve stem, oil deflector caps 31 made of oil-resistant rubber were used.
The valve seats are made of special cast iron and are cold pressed into the heated cylinder head. Plug-in valve seats provide the necessary strength when subjected to shock loads.
38 steel levers transmit force from the camshaft cam to the valve. The lever at one end rests on the spherical head of the adjusting bolt 44 and is held by the spring 39, and the other end, which has a special groove to hold the lever on the valve, rests on its end. The adjusting bolt 44 is screwed into the sleeve, which, in turn, is screwed into the cylinder head. The adjusting bolt is locked with a locknut.