1. Purpose, device, principle of operation

Purpose

The crank mechanism is used to convert the translational movement of the piston under the action of the expansion energy of the combustion products of fuel into the rotational movement of the crankshaft. The crankshaft perceives the forces transmitted from the pistons by the connecting rods and converts them into torque, which is then transmitted through the flywheel to the transmission units.

Device

The mechanism consists of a piston with piston rings and a pin, a connecting rod, a crankshaft and a flywheel.

The cylinder head - common to all four cylinders - is made of aluminum alloy. It is centered on the block with two bushings and fastened with ten screws. Between the block and the head (their surfaces must be dry) a non-shrink metal-reinforced gasket is installed (its reuse is not allowed).

The cylinders are bored directly into the block. The nominal diameter of 82 mm can be increased by 0.4 or 0.8 mm during repairs. The cylinder class is marked on the lower plane of the block in Latin letters in accordance with the cylinder diameter in mm: A - 82.00-82.01, B - 82.01-82.02, C - 82.02-82.03, D - 82 .03-82.04, E - 82.04-82.05. The maximum allowable cylinder wear is 0.15 mm per diameter.

At the bottom of the cylinder block there are five main bearing supports with removable covers, which are attached to the block with special bolts. The caps are not interchangeable (the bores for the bearings are machined complete with the caps) and are marked to distinguish the risks on the outer surface. A steel-aluminum semi-ring is placed in front (from the side of the crankshaft pulley), and a metal-ceramic one in the back. Rings are manufactured with nominal and increased by 0.127 mm thickness. If the axial clearance of the crankshaft exceeds 0.35 mm, one or both half rings change (the nominal clearance is 0.06-0.26 mm).

The liners of the main 13 and connecting rod bearings 11 are thin-walled steel-aluminum. The upper main bearings of the first, second, fourth and fifth bearings installed in the cylinder block are provided with a groove on the inner surface. The lower main bearings, upper third bearing bearing and connecting rod bearings do not have grooves. Repair liners are available for crankshaft journals reduced by 0.25, 0.50, 0.75 and 1.00 mm.

The crankshaft 25 is made of ductile iron. It has five main and four connecting rod journals and is equipped with eight counterweights cast integrally with the shaft. The crankshaft of the 2112 engine differs from the crankshaft of the 2110 and 2111 engines in the form of counterweights and increased strength. Therefore, it is not allowed to install the crankshaft from engines 2110 and 2111 in the engine 2112. To supply oil from the main journals to the connecting rods in crankshaft channels 14 are drilled, the outlets of which are closed with pressed plugs 26.

At the front end of the crankshaft, a toothed camshaft pulley 28 is mounted on a segment key, a pulley for the generator drive 29 is attached to it, which is also a damper for torsional vibrations of the crankshaft. On the ring gear of the pulley, two teeth out of 60 are missing - the cavities serve to operate the crankshaft position sensor.

To the rear end of the crankshaft, with six self-locking bolts through a common washer 21, a flywheel 24 is attached, cast from cast iron, with a pressed steel ring gear 23, which serves to start the engine with a starter. The cone-shaped hole near the flywheel crown should be opposite the crankpin of the fourth cylinder (this is necessary to determine the TDC after assembling the engine).

The connecting rod 3 is made of steel, it is machined together with the cover 1, and therefore they are not interchangeable separately. In order not to confuse the covers and connecting rods during assembly, they are stamped with the number of the cylinder in which they are installed. When assembling, the numbers on the connecting rod and cap must be on the same side.

Piston 4 is cast from a high-strength aluminum alloy. Since aluminum has a high temperature coefficient of linear expansion, in order to eliminate the risk of piston jamming in the cylinder, a temperature-controlled steel plate 5 is filled in the piston head above the hole for the piston pin.

Three grooves for piston rings are machined in the upper part of the piston. The oil scraper ring groove has drillings leading into the bosses, through which the oil collected by the ring from the cylinder walls flows to the piston pin from. The axis of the hole for the piston pin is shifted by 1.2 mm from the diametral plane of the piston towards the location of the engine valves. Due to this, the piston is always pressed against one wall of the cylinder, and piston knocks on the cylinder walls are eliminated when it passes through TDC. However, this requires the piston to be installed in the cylinder in a strictly defined position. When installing the piston, it is necessary to follow the arrow stamped on the bottom (it must be directed towards the crankshaft pulley). The 2112 engine pistons have a flat bottom with four valve recesses (for the 2110 and 2111 engine pistons, the bottom has an oval recess).

It is possible to measure the piston diameter to determine its class in only one place: in a plane perpendicular to the piston pin at a distance of 51.5 mm from the piston crown. In other places, the piston diameter differs from the nominal one, because the outer surface of the piston has a complex shape. It is oval in cross section and conical in height. This shape makes it possible to compensate for the uneven expansion of the piston due to the uneven distribution of the metal mass inside the piston.

Pistons, like cylinders, are divided into five classes according to the outer diameter (marking - on the bottom). Piston diameter (for nominal size, mm): A - 81.965-81.975; B - 81.975-81.985; C - 81.985-81.995; D - 81.995-82.005; E - 82.005-82.015. Pistons of classes A, C and E (nominal and repair sizes) go on sale: the calculated gap between them is 0.025-0.045 mm, and the maximum allowable wear gap is 0.15 mm. It is not recommended to install a new piston in a worn cylinder without boring it: the groove for the upper piston ring in the new piston may be slightly higher than in the old one, and the ring may break on the “step” formed in the upper part of the cylinder when it is worn. For oversized pistons, a triangle (+ 0.4 mm) or a square (+ 0.8 mm) is knocked out on the bottom.

By weight, the pistons are sorted into three groups: normal, increased by 5 g and reduced by 5 g. These groups correspond to the markings on the piston crown: G, + and -.

The pistons of one engine are selected by weight (the spread should not exceed 5 g) - this is done to reduce the imbalance of the crank mechanism.

The piston pin 10 is steel, tubular section, pressed into the upper head of the connecting rod and rotates freely in the piston bosses. From falling out, it is fixed by two locking spring rings, which are located in the grooves of the piston bosses. According to the outer diameter, the fingers are sorted into three categories through 0.004 mm, respectively, to the categories of pistons. The ends of the fingers are painted in the appropriate color: blue - the first category, green - the second and red - the third. Piston rings provide the necessary sealing of the cylinder and remove heat from the piston to its walls. The rings are pressed against the walls of the cylinder under the action of their own elasticity and gas pressure. Three cast-iron rings are installed on the piston - two compression 7, 8 (sealing) and one (lower) oil scraper 6, which prevents oil from entering the combustion chamber.

The upper compression ring 8 operates under conditions of high temperature, aggressive effects of combustion products and insufficient lubrication, therefore, to increase wear resistance, the outer surface is chrome-plated and has a barrel-shaped generatrix to improve running-in.

The lower compression ring 7 has a groove at the bottom for collecting oil during the downward stroke of the piston, while performing the additional function of an oil drop ring. The surface of the ring is phosphated to increase wear resistance and reduce friction against the cylinder walls.

The oil scraper ring has chrome-plated working edges and a groove on the outer surface into which the oil removed from the cylinder walls is collected. A coiled steel spring is installed inside the ring, which unclenches the ring from the inside and presses it against the cylinder walls. Repair size rings are made (as well as pistons) with an outer diameter increased by 0.4 and 0.8 mm.

Engine lubrication - combined. Under pressure, the main and connecting rod bearings, pairs of "support - camshaft journal, hydraulic pushers are lubricated. Oil is sprayed onto the cylinder walls (further to the piston rings and fingers), on the bottom of the pistons, to the pair" camshaft cam pusher and valve stems. The remaining nodes are lubricated by gravity.

Principle of operation

If a charge of a combustible mixture is introduced into the cylinder, necessary to maintain combustion, and then ignited with an electric spark, a large amount of heat will be released and the pressure in the cylinder will increase. The pressure of the expanding gases will be transferred in all directions, including the piston, causing it to move. Since the piston is pivotally connected to the upper head of the connecting rod with a pin, and the lower head of the connecting rod is movably fixed to the crankshaft journal, when the piston moves, the crankshaft and the flywheel attached to its end rotate along with the connecting rod. In this case, the rectilinear movement of the piston with the help of a connecting rod and a crankshaft is converted into a rotational movement of the flywheel.

The first stroke is the inlet - the piston moves from top dead center (BDC) to bottom dead center (BDC), the inlet valve is open and the outlet valve is closed. A vacuum is created in the cylinder, and the combustible mixture fills it. Therefore, the intake stroke serves to fill the cylinder with a fresh charge of the combustible mixture.

The second cycle - compression - the piston moves from n.m.t. to v.m.t., both holes are closed with valves. The volume of the working mixture is reduced by 6.5-7.0 times, the temperature rises to 300-400°C, as a result of which the pressure in the cylinder rises to 10-12 kg/cm2. The compression stroke serves to better mix the working mixture and prepare it for ignition.

The third step is the combustion and expansion of gases. At the end of the compression stroke, an electric spark occurs between the electrodes of the spark plug, which ignites the working mixture. The heat released during the combustion of the working mixture heats the gases to a temperature of 2200-2500°C; while the gases expand and create a pressure of 35-40 kg / cm2, under the influence of which the piston moves down from the top dead center. to n.m.t. Both openings are closed with valves. The movement of the piston is also called the stroke. During the working stroke, the gas pressure acting on the piston through the piston pin and connecting rod is transmitted to the crank, creating a torque on the crankshaft. The working stroke of the piston is used to convert the thermal energy of fuel combustion into mechanical work.

The fourth stroke - release - the piston moves up from n.m.t. to w.m.t. The inlet is closed. The exhaust gases are released from the cylinder to the atmosphere. The purpose of the exhaust stroke is to clear the cylinder of exhaust gases.

When the engine is running, the processes occurring in the cylinder are continuously repeated in the specified order.

The working cycle of an engine is a set of processes occurring in a cylinder in a certain sequence - intake, compression, stroke and exhaust.

The piston, moving in the cylinder, reaches either the upper or lower extreme positions. The extreme positions at which the piston changes direction are called top and bottom dead centers, respectively.

The distance that the piston comes between dead points is called the piston stroke. For each stroke of the piston, the crankshaft will rotate ½ revolution, or 180°. The process that takes place inside the cylinder in one stroke of the piston is called a stroke.

When the piston moves from top dead center to bottom dead center, a space is released in the cylinder, which is called the working volume of the cylinder.

When the piston is at top dead center, there is the smallest space above it, called the volume of the combustion chamber.

The working volume of the cylinder and the volume of the combustion chamber, taken together, make up the total volume of the cylinder. In multi-cylinder engines, the sum of the working volumes of all cylinders is expressed in liters and is called the engine displacement.

One of the important indicators of an engine is its compression ratio, which is determined by the ratio of the total volume of the cylinder to the volume of the combustion chamber. With an increase in the compression ratio of the engine, its efficiency and power increase.

2. The main malfunctions of the crankshaft

A technically sound engine must develop full power, operate without interruption at full load and idling, not overheat, not smoke or let oil through the seals.

The main signs of a malfunction of the crank mechanism are:

1) a decrease in pressure at the end of the compression stroke (compression) in the cylinders;

2) the appearance of noise and knocks during engine operation;

3) gas breakthrough into the crankcase, increased oil consumption;

4) dilution of oil in the crankcase (due to the penetration of working mixture vapors there during compression strokes);

5) oil entering the combustion chamber and getting it on the spark plugs, which causes carbon deposits on the electrodes and sparking worsens. As a result, engine power is reduced, fuel consumption and CO content in exhaust gases increase.

Engine power reduction

- may be accompanied by a difficult start, unstable operation in various modes, an increase in fuel consumption, an increase in the percentage of CO and CH in the exhaust gases.

Causes:

Compression reduction in cylinders:

CPG wear- leads to an increase in the gap, which contributes to the breakthrough of gases from the combustion chamber, under the influence of various factors the geometric shape changes - ovality appears, wear of the cylinders on the cone, since in their upper part the most unfavorable working conditions.

Wear, breakage and loss of piston rings or occurrence in piston grooves

occurs when contaminated oil is not replaced in time or when oils with a high content of varnishes and resins are used, it leads to clogging of the grooves, followed by burning of the rings, which cease to spring and hold back the erupting gases, and their sharp edges begin to “scrape” the cylinder mirror.

Loosening the block head

leads to a breakthrough of both the compressed working mixture and the exhaust gases, which causes a quick burnout of the head gasket and can lead to warping of the head itself, especially when the engine overheats.

Increased noise during operation

Causes:

Increased wear of parts

Poor lubrication of parts

for example, with a low level of lubricant in the oil pan and excessive dilution of it, when using low-viscosity grades in hot climates.

Mechanical damage and emergency breakdowns

Causes:

Violation of assembly technology

Factory defect of parts or their excessive wear during operation

Violation of the normal operation of the engine - for example, strong detonation can lead to burnout of the pistons, breakage of the connecting rods, breakage of the crankshaft.

Turning the bearing shells- usually leads to engine jamming.

3. Diagnosis of KShM

Knocking and noise in the engine occur as a result of wear of its main parts and the appearance of increased gaps between mating parts. Knocks in the engine are heard with a stethoscope, which requires a certain skill.

Usually, with a large wear of the liners, its anti-friction layer melts, which is accompanied by a sharp drop in oil pressure. In this case, the engine must be stopped immediately, as its further operation may lead to breakage of parts.

Increased oil consumption, excessive fuel consumption, the appearance of smoke in the exhaust gases (with a normal oil level in the crankcase) usually appear when the piston rings are stuck or the cylinder rings are worn. The occurrence of the ring can be eliminated without disassembling the engine, for which purpose 20 g of a mixture of equal parts of denatured alcohol and kerosene should be poured into each cylinder of a hot engine overnight through the spark plug hole. Start the engine in the morning, let it run for 10-15 minutes, and then change the oil.

Listening with a stethoscope

Before diagnosing, the engine should be warmed up to the temperature of the coolant (90 + -5) C. Listening is carried out by touching the tip of the sound-sensitive rod in the interface zone of the tested mechanism with the tip of the tip of the sound-sensitive rod.

work piston-cylinder they listen over the entire height of the cylinder at a low crankshaft speed with a transition to a medium one - knocks of a strong dull tone, intensifying with increasing load, indicate a possible increase in the gap between the piston and cylinder, bending of the connecting rod, piston pin, etc.

Pairing piston ring groove check at the NDC level of the piston stroke at an average HF speed - a faint high-pitched knock indicates an increased gap between the rings and piston grooves, or excessive wear or breakage of the rings.

Pairing piston pin - connecting rod bushing check at the TDC level at a low HF speed with a sharp transition to the middle one. A strong high-pitched knock, similar to frequent hammer blows on the anvil, indicates increased wear of the mating parts.

Interfacing work crankshaft - connecting rod bearing listen at low and medium speeds of HF (below BDC). A dull sound of medium tone accompanies the wear of the connecting rod bearings. Knock main bearings HF is listened to in the same zones (slightly lower) with a sharp change in the frequency of rotation of the HF: a strong dull knock of a low tone indicates wear of the main bearings.

Compression test

The compression in the cylinders is determined by a compression gauge, which is a housing with a pressure gauge built into it. The pressure gauge is connected to one end of the tube, at the other end of which there is a spool with a rubber tip, tightly inserted into the hole for the spark plug. Turning the crankshaft of the engine with a starter or crank, measure the maximum pressure in the cylinder and compare it with the standard ones.

For gasoline engines, the nominal compression values ​​are 0.75 ... 1.5 (7 - 15 kgf / cm2). A drop in engine power occurs when piston rings are worn or stuck in the grooves, pistons and cylinders are worn, and the cylinder head is poorly tightened. These faults cause a drop in compression in the cylinder.

Consumption of compressed air supplied to the cylinders

To determine the leakage of compressed air from the over-piston space, a device is used K-69M. Air is supplied to the cylinders of a warm engine either through the reducer 1 of the device, or directly from the line through the hose 4 to the cylinder 7 through the fitting 6, screwed into the hole for the candle or nozzle, to which the hose 3 is connected using a quick coupling 5.

In the first case, they check for air leakage or pressure drop due to non-densities in each engine cylinder. To do this, with the gear knob 1, the device is adjusted so that when the clutch valve 5 is fully closed, the pressure gauge needle is against zero division, which corresponds to a pressure of 0.16 M Pa, and when the valve is fully open and air leaks into the atmosphere, it is against 100% division.

The relative leakage of the cylinder-piston group is checked when the piston of the cylinder under test is installed in two positions: at the beginning and end of the compression stroke. The piston from movement under compressed air pressure is fixed, including the gear in the car gearbox.

The compression stroke is determined by a signaling whistle inserted into the hole of the candle (injector).

The condition of the piston rings and valves is assessed according to the readings of the pressure gauge 2 at the piston position in the top dead center, and the condition of the cylinder (cylinder wear in height) - according to the pressure gauge readings at the piston position at the beginning and end of the compression stroke and by the difference of these readings.

The obtained data are compared with the values ​​at which further operation of the engine is unacceptable. The maximum allowable air leakage values ​​for engines with different cylinder diameters are indicated in the device instructions.

To determine the location of the leak (malfunction), air at a pressure of 0.45-06 MPa is supplied from the line through hose 4 to the engine cylinders.

The piston is installed at the end of the compression stroke at top dead center.

The place of air breakthrough through the leak is determined by listening with a phonendoscope.

Air leakage through the engine valves is detected visually by the fluctuation of the fluffs of the indicator inserted into the hole of the candle (injector) of one of the adjacent cylinders, where the valves are open in this position.

Air leakage through the piston rings is determined only by listening with the piston in the N.M.T. position. in the zone of minimum cylinder wear. Leakage through the cylinder head gasket is detected by bubbles in the radiator neck or in the plane of the connector.

Total clearance in the upper head of the connecting rod and connecting rod bearing

Measuring the total clearances in the upper head of the connecting rod and the connecting rod bearing is another effective method for checking the condition of the crank mechanism. The check is carried out with the engine off using the KI-11140 device.

Tip 3 with the tube of the device is installed in place of the removed spark plug or nozzle of the cylinder being checked. A compressor-vacuum unit is attached to base 2 through a fitting. The piston is installed 0.5 - 1.0 mm from the top dead center. on the compression stroke, they stop the crankshaft from turning and, using a compressor-vacuum unit, alternately create a pressure of 200 kPa and a vacuum of 60 kPa in the cylinder. In this case, the piston, rising and falling, selects the gaps, the sum of which is fixed by indicator 1.

The nominal design clearance is 0.02-0.07 mm for connecting rods.

The amount of gases breaking into the crankcase

Mating condition piston-piston rings-cylinder can be estimated by the amount of gases breaking through into the crankcase. This diagnostic parameter is measured by a flow meter KI-4887-1

1—3 - pressure gauges, 4 inlet pipe, 5, 6 - taps, 7 ejector

Preheat the engine to normal. The device has a pipe with inlet 5 and outlet 6 throttle valves. The inlet pipe 4 is connected to the engine oil filler neck, the ejector 7 for exhaust gases is installed inside the exhaust pipe or connected to a vacuum unit. As a result of rarefaction in the ejector, crankcase gases enter the flow meter. Installing with the help of valves 5 and b the liquid in the columns of pressure gauges 2 and 3 at the same level, they ensure that the pressure in the crankcase cavity is equal to atmospheric pressure. The pressure drop AA is set according to the pressure gauge / the same for all measurements using tap 5. The amount of gases breaking into the crankcase is determined on the scale of the device and compared with the nominal one.

4.Maintenance

At EO the engine is cleaned of dirt, its condition is checked visually and the operation is listened to in different modes.

At T0-1 Check engine mounts. Check the tightness of the connection of the cylinder head, oil pan, crankshaft oil seal. If the head is not tightly connected to the block, oil smudges will be visible on the walls of the cylinder block. With a loose connection between the oil pan and the KV oil seal, they are judged by oil smudges.

At TO-2 Tighten the cylinder head nuts. The aluminum alloy head is tightened on a cold engine with a torque wrench or a conventional one without the use of nozzles. The force should be in the range of 7.5 - 7.8 kgf * m. The lift should be made from the center, gradually moving to the edges and at the same time it should go cross to cross, without jerking (evenly). Tighten the oil pan mounting.

SO Check the condition of the CPG twice a year.

5.Disassembly, repair, assembly, diagnostics

Disassembly

To perform the work you will need: a set of keys, a torque wrench, an inspection hole or overpass, a height-adjustable stop (for example, a screw jack), lifting device(hoist, hoist or winch with a load capacity of at least 100 kg) or a second adjustable stop. The work is best done with an assistant.

1. After loosening the clamp, remove the crankcase ventilation hose from the cylinder block pipe.

2. Using a 10 mm wrench, unscrew the two bolts securing the supply pipe to the cylinder block and disconnect it from the block.

Comment.

The connection is sealed with a gasket

3. Remove the knock sensor

4. Remove the crankshaft position sensor

5. Remove the coolant pump

6. Remove the starter

7. Remove the generator

Remove the camshaft gear pulley

Comment

On 16-valve engines, disconnect the lower engine mounting bar from the front suspension cross member, unscrew the three bolts securing the lower generator bracket with a 17 mm socket wrench and remove the bracket assembly with the bar

8. We install an adjustable stop under the gearbox and hang the cylinder block from the lifting device or install an adjustable stop under the cylinder block. Slightly raise the cylinder block, unloading the supports of the power unit.

9. Remove the bottom cover of the clutch housing and unscrew the bolts securing the gearbox to the cylinder block.

10. Turn off the upper nut of the right support cushion bolt.

11. Using a 13 mm socket wrench, unscrew the three bolts securing the bracket of the right engine support to the cylinder block.

15. Remove the engine support bracket assembly with the upper generator mounting bracket.

16. Using a 15 mm socket wrench under the right front fender of the car, unscrew the three bolts securing the support bracket to the right side member.

17. Remove the bracket together with the right support of the power unit.

18. Slightly rocking the cylinder block, disconnect it from the gearbox and remove it from the engine compartment.

19. Remove the flywheel

20. Using a 10 mm socket wrench, unscrew the six bolts securing the crankshaft rear oil seal holder and remove it.

Comment

A gasket is installed under the holder, which must be replaced during assembly.

21. Remove the oil pump

22. Using a 17 mm socket wrench, unscrew the two bolts of the five main bearing caps.

23. Remove the main bearing caps.

24. We take out the lower shells of the main bearings from the covers.

25. Remove the crankshaft from the cylinder block.

26. We take out two persistent half rings from the grooves of the third support.

27. Remove the upper main bearing shells from the cylinder block supports.

28. We wash the cylinder block from dirt and deposits with a special detergent, diesel fuel or kerosene, and blow through the oil channels.

29. With a thin copper wire, we clean the outlets of the oil nozzles on the VAZ 2112, 21124 and 21114 engines.

30. We wipe the block dry and inspect it. Cracks and chipping of metal are unacceptable.

31. With a micrometer we measure the main journals of the crankshaft, as well as the connecting rod journals.

Repair

Cracks anywhere on the crankshaft are not allowed

The process of rebuilding the crankpins

Table of repair dimensions of inserts and necks of KV

	Indigenous necks	crankpins
Nominal size
1st repair (- 0.25)
2nd repair (- 0.50)
3rd repair (- 0.75)
4th repair (- 1.00)

Repairs are carried out by surfacing in a carbon environment.

Diagnostics

After repair, the shaft must pass through the following parameters

1) Permissible runout of the main surfaces of the crankshaft

Install the crankshaft with extreme main journals on two prisms and check the runout with an indicator:

Main journals and seating surface for the oil pump drive gear (not more than 0.03 mm);

Landing surface for the flywheel (no more than 0.04 mm);

Landing surface for pulleys and surfaces mating with oil seals (no more than 0.05 mm).

The displacement of the axes of the connecting rod journals from the plane passing through the axes of the connecting rod and main journals after grinding should be within ± 0.35 mm. To check, install the shaft with extreme main journals on the prisms and set the shaft so that the axis of the connecting rod journal of the first cylinder is in a horizontal plane passing through the axis of the main journals. Then use an indicator to check the vertical displacement of the crankpins of the 2nd, 3rd and 4th cylinders relative to the crankpin of the 1st cylinder.

Half rings are also replaced if the axial clearance of the crankshaft exceeds the maximum allowable - 0.35 mm. Select new half rings with a nominal thickness or increased by 0.127 mm to obtain an axial clearance in the range of 0.06-0.26 mm.

Measuring the clearance in the connecting rod bearing: 1 - flattened calibrated plastic wire; 2 - insert; 3 - connecting rod cover; 4 - scale for measuring the gap

Remove the cover and, using the scale printed on the package, determine the size of the gap by the flattening of the wire.

The nominal design clearance is 0.02-0.07 mm for connecting rod and 0.026-0.073 mm for main journals. If the gap is less than the limit (0.1 mm for connecting rod and 0.15 mm for main journals), then these liners can be used again.

Assembly

Process the nests with a cutter A.94016/10.

Rinse the CV from abrasive residues and blow it with compressed air.

Degrease the seats for the plugs (white spirit GOST 3134-78, rags TU 68-178-77-82).

Install new plugs of oil channels on the sealant and caulk at 3 points (mandrel A.86010, chisel GOST 7211-72, hammer GOST 2310-77, thread sealant TU 6-10-1048-78).

32. We select the appropriate rings, crankshaft bearing shells

33. Degrease the nests of the liners in the supports and main bearing caps.

34. We put the liners of the main journals with grooves into the sockets of the supports.

35. We put liners without grooves in the bearing caps.

36. We install thrust half rings in the grooves of the third main support. Steel-aluminum on the front side (white on the inside and yellow on the outside), metal-ceramic on the back (yellow on both sides).

Comment

Semi-rings are manufactured in nominal and increased by 0.127 mm thickness. The axial movement of the crankshaft should be within 0.06-0.26 mm

37. We install half rings with grooves outward (to the cheeks of the crankshaft)

38. Lubricate the crankshaft journals and liners with clean engine oil.

39. We put the shaft in the cylinder block supports and install the main bearing caps.

Bearing numbers are marked on the covers with risks (from 1st to 5th). The cover of the fifth main bearing is marked with two risks spaced to the edges of the cover.

When installed in the block, the covers must be marked with the marks facing the side of the block on which the oil level indicator guide is installed.

40. We tighten the bolts for fastening the covers with a torque wrench to a torque of 68.31-84.38 N m (6.97-8.61 kgf m). We tighten the nuts of the connecting rod bolts with a torque of 51 N m (5.2 kgf m)

41. Further assembly is carried out in the reverse order.

6. Ways to restore HF

The restoration of parts is of great economic importance. The cost of restoring parts is 2-3 times lower than the cost of their manufacture. This is due to the fact that when restoring parts, the costs of materials, electricity and labor resources are significantly reduced.

The efficiency and quality of restoration of parts depend on the method adopted.

The most widely used are the following restorations of parts: machining; welding and surfacing; spraying; electroplating and chemical treatment; pressure treatment; the use of synthetic materials.

Machining used as a preparatory or final operation when coating worn surfaces, as well as when restoring parts by processing to a repair size or setting additional repair parts. By processing the parts to the repair size, the geometric shape of their working surfaces is restored, and by installing an additional repair part, they ensure that the dimensions of the part correspond to the dimensions of the new part.

Welding and surfacing- the most common ways to restore parts. Welding is used to eliminate mechanical damage to parts (cracks, holes, etc.), and surfacing is used to apply coatings in order to compensate for the wear of working surfaces. At repair enterprises, both manual and mechanized methods of welding and surfacing are used. Among the mechanized surfacing methods, the most widely used are automatic submerged arc surfacing and shielding gas surfacing and vibro-arc surfacing. Currently, when restoring parts, such promising welding methods as laser and plasma are used.

Spraying as a way to restore parts is based on the application of sprayed metal on worn surfaces of parts. Depending on the method of melting the metal, the following types of spraying are distinguished: arc, flame, high-frequency, detonation and plasma.

Galvanic and chemical processing are based on the deposition of metal on the surface of parts from salt solutions by a galvanic or chemical method. To compensate for the wear of parts, chromium plating, iron plating and chemical nickel plating are most often used. Protective coatings are applied to the surfaces of parts using galvanic processes (chromium plating, nickel plating, zinc plating, copper plating), as well as chemical processes (oxidation and phosphating).

pressure treatment restore not only the dimensions of parts, but also their shape and physical and mechanical properties. Depending on the design of the part, such types of pressure treatment as upsetting, distribution, compression, drawing, knurling, straightening, etc. are used.

The listed methods of restoring parts provide the required level of quality and reliable operation of parts during the established overhaul runs of vehicles. The required level of quality of the restored parts is achieved with the right choice of the technological method, as well as the control of the processes of coating and subsequent processing of parts. The quality of remanufactured parts is affected by the properties of the raw materials used in coating and processing modes.

To restore the connecting rod journals KV to the nominal size:

1) I wash the KV. I measure the diameters of the connecting rod journals. Then I install the HF shaft on the lathe, for this the crankshaft is installed on the machine in such a way that its axis of rotation passes through one of the connecting rod journals, this requires center shifters that align the axis of rotation of the connecting rod journals with the axis of rotation of the machine spindle, and the amount of displacement must be equal to crank radius.(37.8mm)

The offset crankshaft, rotating around the axis of one of the connecting rod journals, is unbalanced. Such a large imbalance during rotation will necessarily lead to deformation of the crankshaft itself and the elements of the machine, as a result of which the quality of crankshaft grinding will drop sharply - the shape of the neck will be distorted (an ellipse will appear), its axis will be non-parallel to the axis of the main journals.

Eliminate or at least significantly reduce the imbalance of the crankshaft allow special weights fixed on the faceplates in front of the chucks of the machine. The mass and location of the balancing weights are selected depending on the mass of the crankshaft and the radius of the crank.

I process (remove the existing risks and scuffs) with a cutter made of VK61 steel and 4 connecting rod journals. After processing, we install the KV in such a way that now the 2nd and 3rd connecting rod journals coincide with the axis of rotation of the machine. I cut off 0.5 mm.

2) I measure the resulting dimensions of the necks. I make surfacing of necks using a VDU-506 welding rectifier in a carbon dioxide environment. I feed the electrode wire to the place of surfacing using the OKS-6569 surfacing head using 30KhGSA wire. (surfacing wire, alloyed structural steel, A-high quality; 0.3% - carbon, X - chromium 1%, G - manganese 1%, C - silicon 1%) with an allowance for turning, grinding and superfinishing.

Surfacing is carried out on constant electrode diameter of 1.2 mm from the cassette is continuously fed into the welding zone. Current 150..190 A and voltage 19…21 Vk is supplied to the electrode wire through the mouthpiece and tip located inside the gas-electric burner. This surfacing speed is 20…30 m/h, electrode wire displacement 18…20 mm, surfacing step 18…20 mm , electrode reach 10…13 mm, carbon dioxide consumption 8…9 l/min. During surfacing, the metal of the electrode and the part is mixed, the thickness of the deposited layer is 0.8…1.0 mm. At a pressure of 0.05 ... 0.2 MPa, carbon dioxide is supplied through the tube to the arc burning zone, which, displacing air, protects the molten metal from the harmful effects of oxygen and nitrogen in the air.

Carbon dioxide from cylinder 7 is supplied to the combustion zone. When leaving the cylinder 7, the gas expands sharply and supercools. To heat it, I pass it through an electric heater 6. The water contained in carbon dioxide is removed using a desiccant 5, which is a cartridge filled with dehydrated copper sulphate or silica gel. The gas pressure is reduced using an oxygen reducer 4, and its flow is controlled by a flow meter 3.

Installation for hardfacing in carbon dioxide

1 - cassette with wire; 2 - surfacing machine; 3 - flow meter; 4 - reducer; 5 - dryer; 6 - heater; 7 - cylinder with carbon dioxide; 8 - detail

3) I process the CV necks on a lathe, leaving a grinding allowance of 0.3-0.5 mm

4) I grind necks using a grinding wheel type 24A40NS 16 A5 (GOST 2424-75) on a ZU131 machine, up to a nominal size of 47.850 mm, leaving an allowance for superfinishing . When the grinding wheel comes into contact with the crankshaft journal, the coolant supply is switched on.

Grinding mode: crankshaft speed 1.03 s "1 (62 rpm), grinding wheel - 13-13.8 s" 1 (780-830 rpm); the grinding wheel is corrected with a diamond pencil grade CI-1 (GOST 607-SO E).

Ovality and taper should not exceed 0.005

5) To finish the necks, instead of polishing, I use superfinishing. I perform superfinishing with a head equipped with abrasive stones on a special semi-automatic machine 3875 K. The grit of the bars is 4-8. Superfinishing evens out the dimensional accuracy. When grinding shafts for superfinishing, an allowance of 0.005 mm is left.

6) I check the HF for runout, ovality and taper of the necks.

7. Chemical composition and mechanical properties of HF

Mechanical properties

Steel is an alloy of iron and carbon that contains up to 2.14% carbon

Steels are classified according to:

1) Chemical composition:

a) carbonaceous

b) doped

2) Purpose:

a) Structural

b) Instrumental

c) Special

3) Quality:

a) Ordinary

b) Quality

c) high quality

d) High quality

4) The degree of deoxidation:

a) Boiling (KP)

b) Calm (SP)

c) Semi-calm (PS)

5) Delivery method are divided into 3 groups:

group A - steel is supplied according to mechanical properties, the letter A is not indicated.

group B - steel is supplied according to the chemical composition

group C = A+B

Cast iron is an alloy of iron with carbon in which carbon contains from 2.14-6.67%.

Cast iron grades.

1. White cast iron. Carbon is in the form of cementite (Fe3C). Hard, brittle, poorly machined.

2. Gray cast iron. Carbon is in the free state in the form of graphite. These are cast irons, in which graphite has the form of plates. Less durable, has casting properties, resists wear well, the ability to dampen vibrations.

3. Alloy gray cast iron. It has a fine-grained structure and a better graphite structure due to additives in small amounts of nickel, chromium and molybdenum, sometimes titanium and copper.

4. Ductile iron. A type of gray cast iron modified with magnesium. At the same time, iron with silicon is introduced into liquid cast iron, as a result graphite is obtained in a spherical shape.

5. Ductile iron. High anti-corrosion properties, works well in humid air, water, flue gases. Parts are made from it that perceive shock loads.

The crankshaft VAZ-2112 is made of HF. The numbers behind the letters HF - ductile iron mean temporary resistance to tensile failure. For example, cast iron grade VCh 60 should have u = 60 kgf / mm 2 or u = 600 MPa. Ductile iron is characterized by the spherical shape of graphite; it is obtained by modifying low-grain gray cast iron with pure magnesium or magnesium-containing additives. Ductile iron has found wide application in the automotive industry (crankshafts and camshafts, gears of various mechanisms, cylinder blocks, etc.), heavy engineering (turbine parts, rolling rolls, hammers, etc.), transport, agricultural engineering (gears and sprockets, clutch discs, various kinds of levers, track rollers, etc.) and in many other industries.

Chemical composition.

It contains: carbon (C)=3.3-3.5%, silicon (Si)=1.4-2.2%, manganese (Mn)=0.7-1.0%, phosphorus (P) = not more than 0.2%, sulfur (S)= not more than 0.15%

Mechanical properties of ductile iron ultimate strength (tensile strength) y in VCh60 = 600 MPa; conditional yield strength y 0.2 = 310-320 MPa; relative elongation (plasticity) d = 10-22%; hardness VCh45 140-225, VCh50 HB 153-245 HB;

Brinell hardness HB= 170-241*10-1 MPa, ?v= 196 MPa

8. Devices used in the repair

Surfacing in carbon dioxide is that the electrode wire from the cassette is continuously fed into the welding zone as shown in the figure. Current is supplied to the electrode wire through a mouthpiece and a tip located inside the gas-electric burner. During surfacing, the metal of the electrode and the part is mixed. At a pressure of 0.05 ... 0.2 MPa, carbon dioxide is supplied to the arc burning zone through a tube, which, by displacing air, protects the molten metal from the harmful effects of oxygen and nitrogen in the air.

Scheme of surfacing in a carbon dioxide environment: 1 - mouthpiece; 2 - electrode wire; 3 - burner; 4 - tip; 5 - burner nozzle; 6 - electric arc; 7 - welding pool; 8 - deposited metal; 9 - welded detail.

Scheme of installation for arc surfacing in carbon dioxide: 1 - cassette with wire; 2 - surfacing machine; 3 - flow meter; 4 - reducer; 5 - dryer; 6 - heater; 7 - cylinder with carbon dioxide; 8 - detail.

Surfacing in a carbon dioxide environment is carried out on a direct current of reverse polarity. The type and brand of the electrode are selected depending on the material of the part to be restored and the required physical and mechanical properties of the deposited metal. The wire feed speed depends on the current strength, which is set in such a way that there are no short circuits and arc breaks during the surfacing process. The rate of surfacing depends on the thickness of the deposited metal and the quality of formation of the deposited layer. The surfacing of the beads is carried out with a step of 2.5 ... 3.5 mm. Each subsequent roller must overlap the previous one by at least 1/3 of its width.

The hardness of the deposited metal, depending on the brand and type of electrode wire, is 200...300 HB.

The consumption of carbon dioxide depends on the diameter of the electrode wire. Gas consumption is also affected by deposition rate, product configuration and presence of air movement.

After having applied, a certain layer of metal, we begin the external surface treatment by grinding.

After installing the workpiece, stops are placed to measure the direction of movement of the table. Longitudinal feed stops are positioned so that the wheel does not touch the collar during grinding and does not get out of contact with the workpiece. Installed stops must be firmly fixed. To establish the relative position of the circle and the workpiece, a reference part is installed in the centers. Its left end is used as a base for installing a grinding headstock. For any length of the workpiece to be ground, the position of this end face remains unchanged.

Before trial grinding, the electric motor of the grinding wheel is first turned on, then the electric motor for rotating the workpiece. Then they bring the circle to the workpiece until a spark appears and manually move the table. After completing two or three passes, the automatic feed is turned on and, after test grinding, the diameters of the workpiece are measured at both of its ends. If there is a taper, then the position of the table is adjusted, achieving the cylindricality of the treated surface.

The screw-cutting lathe is designed for external and internal processing, including threading, single and small groups of parts

General view and placement of the controls of the screw-cutting lathe model 16K20

1 - frame, control handles: 2 - interlocked control, 3,5,6 - setting the feed or pitch of the thread being cut, 7, 12 - controlling the spindle speed, 10 - setting the normal and increased thread pitch and for cutting multi-start threads, 11 - changing the direction of threading (left or right), 17 - moving the upper slide, 18 - fixing the quill, 20 - fixing the tailstock, 21 - the steering wheel for moving the quill, 23 - turning on the accelerated movements of the caliper, 24 - turning on and off the lead screw nut, 25 - control of changing the direction of rotation of the spindle and stopping it, 26 - turning the feed on and off, 28 - transverse movement of the sled, 29 - turning on the longitudinal automatic feed, 27 - button on and off the main motor, 31 - longitudinal movement of the sled; Machine components: 1 - bed, 4 - feed box, 8 - main drive belt drive housing, 9 - headstock with main drive, 13 - electrical cabinet, 14 - screen, 15 - protective shield, 16 - upper slide, 19 - tailstock , 22 - longitudinal movement support, 30 - apron, 32 - lead screw, 33 - bed guides.

Circular grinding machine - designed for processing parts by grinding.

General view of the universal cylindrical grinding machine mod. ZU131:

1 - bed, 2 - electrical equipment, 3 - headstock, 4 - device for internal grinding, 5 - grinding wheel casing, 6 - grinding headstock feed mechanism, 7 - grinding headstock, 8 - tailstock, 9 - hydraulic drive and lubrication system, 10 - hydraulic control system, 11 - grinding wheel, 12 - manual movement of the table

Welding universal rectifier VDU-506. It is an adjustable thyristor rectifier with a hard or falling external characteristic. The difference from the VDU-506S version is the classic construction and the absence of a combined current-voltage characteristic in the semi-automatic welding mode. Works in a set with a semiautomatic device PDGO-510-5, with stabilization of the welding wire feed speed and the possibility of removing the feeder from the rectifier at a distance of up to 30m, it is optimal for workshop conditions when welding at arc currents up to 450A (PV=100%).

The micrometer is smooth. A smooth micrometer is a means for measuring external linear dimensions. The division value of the micrometer is 0.01 mm.

1 - bracket; 2 - hard heel; 3 - gauge (end measure) for setting the micrometer to zero; 4 - movable heel (microscrew); 5 - stem; 6 - micrometer head; 7 - installation cap; 8 - ratchet device; 9 - brake device. price of division of the drum scale, mm ...... 0.01

Dial indicator called a measuring head, i.e. a measuring instrument with a mechanical transmission that converts small movements of the measuring tip into large movements of the arrow observed on the dial scale.

a - general view; b - gear diagram

In terms of external and internal structure, this indicator looks like a pocket watch, which is why such a name was assigned to it.

Structurally, the dial indicator is a measuring head with a longitudinal movement of the measuring tip. The basis of this indicator is housing 13, inside of which a converting mechanism is mounted - a rack and pinion gear. A meter passes through the body - a rod-rail with a measuring tip 4. On the rod 1, a rail of movement is cut which is transmitted by rack (5) and gear (7) gears, as well as a tube 9 to the main arrow 8. The amount of turn of the arrow 8 is read off on a circular scale - dial . To set the indicator against the “O” mark, the circular scale is rotated by the rim 2.

The circular scale of the dial indicator consists of 100 divisions, the value of each division is 0.01 mm. This means that when the measuring tip is moved 0.01 mm, the indicator needle will move one division of the dial.

10.Cutting tool

Turning tool. Serves to remove a layer of metal or shavings to give the product a given shape or size.

The cutters consist of a working part (head) and a rod (body).

On the working part, by sharpening, the following are formed:

the front surface along which the chips descend;

rear main surface facing the cutting surface;

rear auxiliary surface facing the machined surface.

The intersection of the front and rear main surfaces forms the main cutting blade, which performs the main work of cutting.

The intersection of the front and rear auxiliary surfaces forms an auxiliary cutting blade that cuts off a smaller part of the removed layer of material.

Depending on the purpose, the cutters have one or two auxiliary cutting blades and, accordingly, one or two rear auxiliary surfaces.

Р6М5 - high-speed steel, tool, alloyed; P6 - high-speed 6% tungsten, M5 - molybdenum 5%.

Cutters made of tool steel withstand heating up to 600˚С without losing their cutting properties. After heat treatment, high speed steel tools have a hardness of HRC 62-63.

Also, for the manufacture of cutters, tungsten-cobalt alloys (VC) are used for processing brittle materials: cast iron, bronze, porcelain. They consist of tungsten and cobalt carbides, the alloys contain up to 10% cobalt. Heat resistance VK 900˚С: VK6, VK8. VK8 - tungsten hard alloy, K8 - cobalt 8%, the rest is tungsten carbide. Titanium-cobalt alloys (TC) have a higher hardness than tungsten-cobalt alloys. The heat resistance of TK is also 1000˚С, however, their strength is lower (with the same cobalt content). Alloys T15K6, T5K10 are used for processing materials with drain chips - steels. T15K6 - titanium-cobalt alloy, T15 - titanium 15%, K6 - cobalt 6%, the rest is carbide-titanium.

Grinding wheel

An abrasive tool is made from artificial and natural abrasive materials by pressing a mass consisting of grinding grain (abrasive is small, hard, sharp particles) and a bundle, followed by thermal and mechanical processing. Abrasives are used for mechanical processing (including shaping, roughing, grinding, polishing) of various materials and products from them. The action of abrasives is to remove part of the material from the treated surface. Abrasives usually have a crystalline structure and wear out during operation in such a way that tiny particles break off from them, in place of which new sharp edges appear (due to brittleness). According to the grain size, abrasives are characterized by a scale from 4 (coarse) to 1200 (finest).

Surface treatment with grinding wheels provides a roughness of Ra 1.25-0.02 µm.

Schemes of circular external grinding:

a - grinding with longitudinal working strokes: 1 - grinding wheel; 2 - polished workpiece; b - deep grinding; c - plunge grinding; g - combined grinding; S np- longitudinal feed; S n- transverse feed; t - processing depth

Devices for mounting and fastening grinding wheels:

1 - spindle; 2 - flanges; 3 - grinding wheels; 4 - gaskets; 5 - nuts; 6, 7 - adapter flanges; 8 - annular groove; 9 - screws

11. Workplace of a car mechanic

The workplace is a section of the area, suitably equipped and equipped to perform work by one worker or a team of workers. It must be provided with everything necessary for the smooth execution of the production task, and the work must be carried out in strict accordance with the regulated technology.

A car repair mechanic of a motor transport enterprise performs work related to the maintenance and current repair of rolling stock at specialized posts in garage modules.

To perform maintenance and current repairs, the posts are equipped with inspection devices that provide access to the car from all sides.

Organization of the workplace of a car mechanic:

1 - lifting and swivel chair; 2 - two-pedestal workbench; 3 - table for washing and drying parts; 4 - rack-stand; 5 - beam crane, load capacity 1 t

Inspection ditches in width are divided into:

- narrow (inter-track) (Fig. 20 a);

- wide (Fig. 20 c).

They can be dead-end or straight-through. From dead-end ditches, cars move out in reverse, from straight-through ditches - in front.

The length of the ditch should exceed the length of the car by 1.0-1.2 m, and the depth is 1.4-1.5 m for cars and 1.2-1.3 m for trucks and buses. The width of a narrow ditch is 0.9–1.1 m, and a wide one is 1.4–3.0 m.

The ditches have stepped ladders, from the sides along the edge - guide flanges for the wheels of the car. Niches with lamps are equipped in the ditches, which can be used to store tools. The walls of the ditches are lined with ceramic or plastic tiles.

Lifts are designed to lift vehicles and facilitate access to them from below.

Lifts can be:

Stationary:

Hydraulic (single and double plunger)

Electromechanical (two-, three- and four-post)

Mobile:

hydraulic jacks

Lifts with hydraulic or mechanical drive, placed in the inspection ditch.

Tool and fixtures. Maintenance posts, depending on the purpose, are equipped with the necessary set of fixtures and tools.

To perform disassembly and assembly work, use sets of fitter's and assembly tools (Fig. 21), torque wrenches and pullers.

The set of metalwork and assembly tools includes:

- double ended wrenches;

- face interchangeable heads;

- adjustable wrench;

— spanner double-sided wrenches;

— metalwork hammer;

- beard;

— pliers;

— screwdrivers;

- rotator;

-special keys (for studs, spark plugs, etc.).

Tool kit for fitter

When assembling critical threaded connections (fastening the cylinder head, connecting rod caps, etc.), a torque wrench is used to tighten the nuts and bolts with a certain force. The tightening torque (in kilogram meters) is determined by a scale (indicator) specially installed on the key.

Torque wrench:

1 - head; 2 - arrow; 3 - scale; 4 - handle; 5 - elastic rod

To unscrew and wrap the studs, an eccentric wrench is used (Fig. 23), having a roller with a knurled surface and fixed eccentrically on the key axis. A hollow rack is put on a hairpin, retracting the roller. When the key is turned by the knob, the axis is wedged and rotates together with the key, ensuring the screw is screwed out or screwed in.

Eccentric wrench for studs:

1 - rack; 2 - collar; 3 - axis;

4 - roller

When servicing vehicles, various types of pullers are used, which can be both universal and designed to perform a specific operation.

Pullers:

a - valve; b - water pump impellers; in - gears; 1 - bracket; 2 - screw.

1. Before maintenance or repair of the machine on the lift (hydraulic, electromechanical) on the lift control panel, post a warning sign “Do not touch - people are working under the car!” Secure the lift plunger against spontaneous lowering with a stop (rod).

2. Drain gasoline, oil and water when repairing parts and assemblies associated with cooling and lubrication systems. Avoid splashing and spilling liquids.

Accidentally spilled liquids should be covered with sand or sawdust, which must then be removed with a shovel and brush.

3.Ensure the safety of working under the machine:

Slow down with a hand brake;

Engage low gear;

Switch off the ignition (fuel supply);

Put stops (shoes) under the wheels.

4. During work related to turning the crankshaft or cardan shaft, additionally check the ignition off, fuel supply (for diesel vehicles), put the gear lever in neutral position, release the hand brake lever.

After completing the necessary work, apply the handbrake and re-engage the lower gear

5. When repairing the machine outside the inspection ditch, overpass or lift, use sunbeds or bedding.

6. Climb under the car and get out from under it only from the side opposite to the passage. Placed under the machine between the wheels along the machine.

7. Before removing and installing units and assemblies (engines, springs, rear and front axles, etc.), unload them from the weight of the body by lifting the body with a lifting mechanism, followed by installation of the trestles.

8. Disassembly and assembly of springs should be carried out using special tools. Check the alignment of the hole of the spring ear and the earring only with the help of a beard or mandrel. It is forbidden to perform such a check with your fingers.

9. Removal of individual units and parts (brake and valve springs, drums, spring pins, etc.), associated with the application of significant physical exertion or inconvenience in work, should be carried out using devices (pullers) that ensure the safety of work.

10.Before removing the wheels, make sure that the machine is securely installed on the trestle and that there are stops under the wheels that have not been removed.

11. Before removing the tire, completely bleed the air from the wheel chamber.

12. Dismantling and mounting of tires should be carried out in the tire fitting department using special equipment and tools for these works with the use of safety fences.

13.Before assembling the wheel, check the condition of the removable rim flanges and the retaining ring. Rim flanges and retaining rings must be free from rust, dents, cracks, burrs. Wheel rims, circlips and removable flanges must match the tire size.

14.When mounting the tire, insert the retaining ring with its entire inner surface into the recess on the wheel disk.

15. It is necessary to inflate tires with air in special devices. Before inflation, make sure that the locking ring lies completely in the locking groove. It is allowed to correct the position of the tire on the disk by tapping only after the air supply has stopped.

16. Before servicing and repairing the bottom of a car body on a turntable, it is necessary to fix the car on it, drain the fuel from the fuel tanks and water from the cooling system, close the engine oil filler tightly and remove the battery.

17. It is necessary to wash the parts with kerosene in a specially designated place. Blow them with compressed air in special closed cabinets equipped with exhaust ventilation.

18. Clearly coordinate their actions when performing work together with other workers.

Maintenance and repair of the car with the engine running, except for the cases of adjusting the power supply systems and electrical equipment and testing the brakes;

Carry out repair work on a car hung out only on one lifting mechanism, without stands;

Work under the car without sunbeds or bedding, lying on the ground or floor;

Use random objects (boards, bricks, etc.) as coasters or brake stops (shoes);

Work with damaged or incorrectly installed stops, as well as install a loaded body on the stops;

Knock out wheel disks with a sledgehammer or hammer during dismantling;

While inflating the tire, push the retaining ring with a hammer or sledgehammer;

Approach open flames, smoke or light matches if hands or overalls are moistened with gasoline.

20. Before testing and testing the brakes on the test stand, secure the vehicle with a chain or cable to prevent it from rolling off the test stand.

21. Before starting the engine, slow down the car, put the gear lever in neutral position.

22. Start the engine using a starter. Start the engine with the hood open in the absence of unauthorized persons at the workplace.

When running the engine on the stand, touch the rotating parts;

Engine operation in a closed, non-ventilated area

Bibliography

Epifanov L.I., Epifanov E.A. Maintenance and repair of cars: Textbook for students of institutions of secondary vocational education. - M.: FORUM: INFRA-M, 2003.- 280 p.: ill. - (Series "Professional Education")

Karagodin V.I., Mitrokhin N.N. Repair of cars and engines: Proc. for stud. avg. prof. textbook establishments. - M.: Mastery; Higher school, 2001. - 496 p.

Kozlov Yu.S. Materials Science. Publishing house "ATAR", 1999 - 180 p.

Kubyshkin Yu.I., Maslov V.V., Sukhov A.T. VAZ-2110, -2111, -2112. Operation, maintenance, repair, tuning. Illustrated guide. - M .: CJSC "KZHI "Behind the wheel", 2004. - 280 p.: ill. - (Series "On Your Own").

Shestopalov S.K. Device, maintenance and repair of cars: Proc. for the beginning prof. education; Proc. allowance for Wednesdays. prof. education. - 2nd ed., erased. - M.: Publishing Center "Academy"; ProfObrIzdat, 2002. - 544 p.

Adaskin A.M. Materials science (metalworking): Textbook for the beginning. prof. Education: Proc. allowance for Wednesdays. prof. education / A. M. Adaskin, V. M. Zuev. - 3rd ed., ster. - M .: Publishing Center "Academy", 2004. - 240 p.

Makienko N.I. General plumbing course: Proc. for vocational schools. - 3rd ed., Rev. - M.: Higher. school, 1989. - 335 p.: ill.

It's no secret that the main mechanism that sets the car in motion is the engine. Those. we can say that the power unit is the heart of any machine. But without a crank mechanism, the operation of an internal combustion engine is impossible. It turns out that the KShM is nothing but the heart of the engine. And it is about this mechanism that Auto-Gurman.ru will tell below.

Crank mechanism. What it is?

KShM is a mechanism that transforms one movement into another. That is, for example, it can convert rotation into rocking, translational-pushing and other movements.

You can meet the crank mechanism not only in reciprocating internal combustion engines, but also in various compressors, pumps and other mechanical devices.

To date, KShM is the most popular mechanism for converting one movement into another. Therefore, now it is worth considering its device.

KShM device

The main elements of the mechanism are divided into two groups:

1. Movable;

2. Fixed.

The moving parts are pistons, piston rings, pins, crankshaft with flywheel and connecting rod. All piston elements are a piston group.

The fixed elements are the connecting parts, the cylinder block and its head, as well as the pan and crankcase with crankshaft bearings.

Let's analyze each element in more detail.

Piston
The piston is an element of the KShM that changes the gas pressure. Such changes are carried out by its reciprocating motion.

Externally, the piston is made in the form of a cylinder made of aluminum alloy. The main parts of the piston are the bottom, skirt and head. Each detail performs its function. The bottom has a combustion chamber. In the head there are special cut grooves in which the piston rings are located. The main purpose of the rings is to protect the engine crankcase from gases and remove excess oil from the cylinder walls. The skirt inside has a piston pin, which is placed in this element of the mechanism due to special bosses.

There are two bosses in the skirt to accommodate the piston with the pin connecting rod.

connecting rod
The connecting rod is the main element of the crank mechanism for transmitting piston force to the crankshaft. This part can be forged from steel or titanium.

By design, the connecting rod consists of a rod with an I-section, as well as heads (upper and lower). The upper head, like the skirt, has bosses in which the piston pin is located, and the lower collapsible head ensures high precision in connecting parts.

Block and cylinder head
The cylinder block has special cooling jackets, attachment points for the main components and instruments, as well as a bed for crankshaft and camshaft bearings.

The block itself and the head are cast from cast iron or aluminum. Well, the main purpose of the block is the direction of the pistons.

As for the block head, it has inside it special holes for spark plugs, inlet-outlet channels, bushings, as well as a combustion chamber and pressed seats.

Crankshaft
The crankshaft is an element for the perception of forces from the connecting rod, which further converts these efforts into torque. Most often it is made of cast iron or steel. It consists of root and connecting rod necks. The necks are connected by special cheeks. Their main working process takes place directly in the plain bearings. Cheeks and necks have special holes for oil supply.

Flywheel
The flywheel is located at the end of the crankshaft. He plays one of the main roles in the operation of the engine - he participates in starting the internal combustion engine through the starter.

Here are the main elements of the crank mechanism. Now Auto-Gurman.ru wants to introduce you to the principle of operation of the KShM.

Crank mechanism: principle of operation

And so, the piston is at the maximum distance from the crankshaft. Crank and connecting rod lined up in one line. At this point, fuel enters the cylinder and it starts to burn. Combustion products, namely expanding gases, move the piston to the crankshaft. Along with this, the connecting rod also moves, the lower head of which rotates the crankshaft 180 °. After that, the connecting rod and its head are moved and rotated in the opposite direction, returning to their original position. The piston also returns to its original place. And this process of work goes in a circle.

As you can see, the crank mechanism is the main mechanism of the engine, on the operation of which the serviceability of the car depends. Therefore, this unit must always be monitored and, with any signs of a malfunction, eliminate it as quickly as possible, since the result of KShM breakdowns can be a complete failure of the engine, the repair of which will greatly affect the personal budget.

The crank mechanism (KShM) is an important mechanism of an automobile engine, which converts the translational movements of the piston system into rotational movement of the engine crankshaft, from which, in turn, this movement is transmitted to the wheels of the car, which sets the car in motion.

The principle of operation of the crank mechanism

Under the pressure of gases that are formed in the engine cylinders during the combustion of the fuel-air mixture, the piston makes a translational movement towards the crankshaft.

Important parts of the mechanism, namely: a piston, a connecting rod and a shaft, help to convert translational movements into rotational movements, which in turn starts the rotation of the car's wheels.

"Cshaft". Under Public domain license from Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Cshaft.gif#mediaviewer/%D0%A4%D0%B0%D0%B9%D0%BB:Cshaft.gif

In reverse order, the interaction of the shaft and the piston is as follows: the shaft, during rotational movement through the details of the mechanism - the shaft, connecting rod and piston, converts energy into translational piston movement.

By A. Schierwagen using OpenOffice Draw , via Wikimedia Commons

How is the crank mechanism

Figure: http://mediaport.net.ua

The mechanism consists of parts, both movable and fixed.

Moving type parts:

• piston;
• oil scraper ring (1);
• compression rings (2);
• piston pin (3);
• retaining ring (4);
• connecting rod;
• connecting rod cover (5);
• fixing bolt (6);
• liners (7);
• sleeve (8);
• crankshaft;
• crankpin (9);
• counterweight (10);
• root neck (11);
• flywheel

Fixed type parts:

• block and cylinder head ;

Piston with rings and pin

Piston- This is a small cylindrical part made of aluminum alloy. Its main purpose is to convert the pressure of the emitted gases into translational motion transmitted to the connecting rod. The reciprocating movement is provided by the sleeve.

The piston consists of a skirt, a head and a bottom (bottom). The bottom can have a different shape (convex, concave or flat), it contains a combustion chamber. On the head are small grooves for piston rings (oil scraper and compression).

Compression type rings prevent possible ingress of gases into the engine crankcase, and low-removable type rings are designed to remove excess oil from the cylinder walls.

The skirt is equipped with special bosses with holes to install the piston pin connecting the piston and connecting rod.

connecting rod

The connecting rod is another part of the KShM, which is made of steel by stamping or forging, equipped with swivel joints. The connecting rod is designed to transfer the energy of movement from the piston to the shaft.

The connecting rod consists of an upper, collapsible lower head and a rod. The top head is connected to the piston pin. The lower collapsible head can be connected to the shaft neck using covers (connecting rod).

Crank (knee)

A piston connecting rod is attached to any crank (knee). Often the crank is located from the axis of the necks in a certain radius, which determines the piston stroke. It was this detail that gave the name to the crank mechanism.

Crankshaft

Another moving part of the mechanism of complex configuration, made of cast iron or steel. The main purpose of the shaft is to convert the translational piston movement of the piston into torque.

The crankshaft consists of necks (main, connecting rod), cheeks (connecting necks) and counterweights. Cheeks create balance during the operation of the entire mechanism. Inside the neck and cheeks are equipped with small holes through which oil is supplied under pressure.

Flywheel

The flywheel is usually mounted on the end of the shaft. Made from cast iron. The flywheel is designed to increase the uniform rotation of the shaft to start the engine using a starter.

At present, flywheels of a two-mass type are more often used - two disks that are quite tightly interconnected.

Cylinder block

This is a fixed part of the KShM, which is made of cast iron or aluminum. The block is designed to guide the pistons, it is in them that the entire workflow is carried out.

The cylinder block can be equipped with cooling jackets, beds for bearings (camshaft and crankshaft), attachment point.

cylinder head

This part is equipped with a combustion chamber, channels (inlet and outlet), spark plug holes, bushings and seats. The cylinder head is made of aluminium.

Like the block, the head also has a cooling jacket that connects to the cylinder jacket. But the tightness of this connection is provided by a special gasket.

The head is closed with a small stamped cap, while a rubber gasket resistant to oils is installed between them.

The piston, cylinder liner, and connecting rod form what motorists commonly refer to as a cylinder. An engine can have anywhere from one to 16 or sometimes more cylinders. The more cylinders, the greater the total displacement of the engine and, accordingly, the greater its power. But you need to understand that at the same time as power increases, fuel consumption also increases. The cylinders in the engine can be located according to various layout schemes:

• in-line (axes of all cylinders are located in the same plane)
• V-shaped layout (cylinder axes are located at an angle of 60 or 120 degrees in two planes)
• boxer arrangement (cylinder axes are at an angle of 180 degrees)
• VR layout (similar to V-layout, but the planes are at a slight angle relative to each other)
• W-shaped layout is a combination on one crankshaft of two VR-layouts arranged in a V-shape with an offset relative to the vertical

The balancing of the engine, as well as its size, depends on the layout scheme. The boxer engine has the best balance, but it is rarely used on cars due to design features.

The in-line six-cylinder engine also has an excellent balance, but its use on modern cars is almost impossible due to its bulkiness. The most widespread are V-shaped and W-shaped engines due to the best combination of dynamic characteristics and design features.

The crank mechanism (KShM) is perhaps the most important engine system.
The purpose of the crank mechanism is to convert reciprocating motion into rotational and vice versa.

All parts of the crank mechanism are divided into two groups: movable and fixed. Moveables include:

• piston,
• crankshaft,
• flywheel.

For immovables:

• cylinder head and block
• crankcase cover.

Crank mechanism device

The piston looks like an inverted glass in which the rings fit. On any of them there are two types of rings: oil scraper and compression. Oil scraper usually put two, and compression - one. But there are exceptions in the form: two of these and two of these - it all depends on the type of engine.

The connecting rod is made of an I-beam steel profile. It consists of an upper head, which is connected to the piston with a pin, and a lower head, which is connected to the crankshaft.

The crankshaft is made mainly of high strength cast iron. Represents a non-aligned rod. All necks are carefully polished, in compliance with the necessary parameters. There are main journals - for installing main bearings, and connecting rod - for installation through the connecting rod bearings.

The role of plain bearings is performed by split half-rings, made in the form of two inserts, which are treated with high-frequency currents for strength. All of them are covered with an anti-friction layer. The main ones are attached to the engine block, and the connecting rods are attached to the lower head of the connecting rod. In order for the liners to work well, grooves are made in them for oil access. If the liners are turned, it means that there is insufficient oil supply to them. This usually occurs when the oil system is clogged. The inserts are not repairable.

The longitudinal movement of the shaft is limited by special thrust washers. It is mandatory to use different seals at both ends to prevent oil from escaping from the engine lubrication system.

Attached to the front of the crankshaft is a cooling system drive pulley and a sprocket that drives the camshaft using a chain drive. On the main models of cars produced today, a belt has come to replace it. A flywheel is attached to the rear of the crankshaft. It is designed to eliminate shaft imbalance.

It also has a ring gear designed to start the engine. So that during disassembly and further assembly there are no problems, the flywheel is fastened according to an asymmetric system. The ignition timing also depends on the location of the marks for its installation - therefore, the optimal operation of the engine. During manufacture, it is balanced together with the crankshaft.

The engine crankcase is manufactured together with the cylinder block. It serves as the basis for fastening the timing and KShM. There is a pan that serves as a container for oil, as well as to protect the engine from deformation. Below there is a special plug for draining engine oil.

The principle of operation of the KShM

The piston is pressurized by gases that are produced during the combustion of the fuel mixture. At the same time, it performs reciprocating movements, forcing the crankshaft of the engine to rotate. From it, the rotational movement is transmitted to the transmission, and from there to the wheels of the car.

But the video shows how KShM works in:

The main symptoms of a KShM malfunction:

• knocks in the engine;
• power loss;
• decrease in oil level in the crankcase;
• increased opacity of exhaust gases.

The crank mechanism of the engine is very vulnerable. Regular oil changes are essential for efficient operation. It is best to produce it at service stations. Even if you have recently changed the oil, and it's time for seasonal maintenance, be sure to switch to the oil that is indicated in the machine's operating instructions. If there are any problems in the operation of the engine: noises, knocks - contact the specialists - only in an authorized center you will be given an objective assessment of the condition of the car.

The engine is perhaps the most critical unit in a car. It is he who generates the torque for the further movement of the machine. The design of the internal combustion engine is based on a crank mechanism. Its purpose and device will be discussed in our today's article.

Design

So, what is this element in the engine?

This mechanism perceives the energy of gas pressure and converts it into mechanical work. KShM of an internal combustion engine combines several components, namely:

• piston;
• connecting rod;
• crankshaft with liners;
• rings and bushings.

Together they form a cylinder-piston group. Every detail of the crank mechanism does its job. At the same time, the elements are interconnected. Each detail has its own device and purpose. The crank mechanism must withstand increased shock and temperature loads. This determines the reliability of the power unit as a whole. Next, we will describe in detail each of the above components.

Piston

This part of the crank mechanism perceives the pressure of expanding gases after the ignition of the combustible mixture in the chamber. The piston is made of aluminum alloys and performs reciprocating movements in the block sleeve. The design of the piston combines the head and the skirt. The first can have a different shape: concave, flat or convex.

On 16-valve VAZ engines, pistons with recesses are often used. They serve to prevent the piston head from colliding with the valves in the event of a broken timing belt.

Rings

Also in the design there are rings:

• oil scraper;
• compression (two pieces).

The latter prevent gas leakage into the crankcase. And the first ones serve to remove excess oil that remains on the walls of the cylinder during the piston stroke. In order for the piston to connect to the connecting rod (we will talk about it below), bosses are also provided in its design.

connecting rod

The operation of the crank mechanism is not complete without this element. The connecting rod transmits pushing forces from the piston to the crankshaft. Data and mechanisms have Usually connecting rods are made by forging or stamping. But on sports engines, titanium cast elements are used. They are more resistant to stress and do not deform in the event of a large push.

What is the device and purpose of the crank mechanism? Structurally, the connecting rod consists of three parts:

• top head;
• rod;
• lower head.

At the top, this element is connected to the piston with a finger. The rotation of the part is carried out in the same bosses. This type of finger is called floating. The rod at the connecting rod has an I-section. The lower part is collapsible. This is necessary in order to dismantle it from the crankshaft in case of malfunctions. The lower head is connected to the crankshaft journal. We will consider the device of the latter right now.

Crankshaft

This element is the main component in the device of the crank mechanism. Its purpose is as follows. takes the load from the connecting rod. Then he converts them into torque, which is subsequently transmitted to the box through the clutch mechanism. A flywheel is attached to the end of the shaft. It is he who is the final part in the design of the engine. It can be single or double mass. At the end it has a toothed crown. It is needed to engage with the starter gear in case the engine starts. As for the shaft itself, it is made of high-strength grades of steel and cast iron. The element consists of connecting rod and main journals, which are connected by "cheeks". The latter rotate in liners (sliding bearings) and can be split. Inside the cheeks and necks there are holes for oil supply. The lubricant penetrates under pressure from 1 to 5 bar, depending on the load on the internal combustion engine.

Shaft imbalance may occur during engine operation. To prevent it, a torsional vibration damper is provided in the design. It consists of two metal rings that are connected through an elastic medium (motor oil). There is a belt pulley on the outer ring of the absorber.

CPG types

At the moment, there are several varieties of the cylinder-piston group. The most popular is the row design. It applies to all 4-cylinder engines. There are also in-line "sixes" and even "eights". This design assumes the placement of the axis of the cylinders in one plane. are highly balanced and have low vibration.

There is also a V-shaped design, which came from the Americans. The scheme of the crank mechanism V-8 is shown below in the photo.

As you can see, here the cylinders are located in two planes. Usually they are at an angle of 75 to 90 degrees relative to each other. Thanks to this design, you can significantly save space in the engine compartment. An example is the 6-cylinder engines from Opel C25XE. This V-shaped engine is placed transversely under the hood without any problems. If you take the in-line "six" from the front-wheel drive "Volvo", it will noticeably hide the place under the hood.

But for compactness you have to pay less vibration resistance. Another layout of the cylinders is opposed. Practiced on Japanese Subaru cars. The axes of the cylinders are also placed in two planes. But unlike the V-shaped design, here they are at an angle of 180 degrees. The main advantages are a low center of gravity and excellent balance. But such engines are very expensive to manufacture.

Repair and maintenance of the crank mechanism

Maintenance of any KSHP involves only a regular change of oil in the engine. In case of repair, attention is paid to the following elements:

• Piston rings. When they lie down, they change to new ones.
• crankshaft liners. In case of significant wear or turning of the plain bearing, replace it with a new one.
• piston pins. They also have output.
• The pistons themselves. During detonation, burnout of the head is possible, which entails a decrease in compression, tripling, oil consumption and other problems with the engine.

Often, such malfunctions occur when the oil and filter are not changed in time, as well as when using low-octane gasoline. Also, KShM repair may be needed at constant loads and at high mileage. Parts of machines and mechanisms usually have a high margin of safety. But there are cases when, already at 120 thousand kilometers, valves and pistons burned out. All this is a consequence of untimely maintenance of the power unit.

So, we found out what the crank mechanism is, what elements it consists of.