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The crankshaft is steel, made by hot stamping. All surfaces of the shaft are nitrided and the depth of the nitrided layer is at least 0.35 mm. The crankshaft has five main bearings and four connecting rod journals. Connecting rods are installed on the connecting rod journals (two for each). The main and connecting rod journals are lubricated with pressurized oil during operation. Oil is supplied to the main bearings, and then, through inclined channels to the connecting rod journals. The connecting rod journals have internal cavities closed with plugs, where the oil undergoes additional centrifugal cleaning.

To balance the engine and unload the main bearings from the inertial forces of the moving masses of the pistons and connecting rods and unbalanced centrifugal forces on the cheeks crankshaft counterweights are installed, in assembly with which the shaft is balanced. In addition, the balancing system includes two remote masses, one of which is made in the form of a recess on the flywheel mounted on the rear end of the crankshaft, the other is a counterweight mounted on the front end of the crankshaft.

Axial fixation of the shaft is carried out by four bronze half-rings installed in the grooves of the rear main bearing. To prevent rotation, the lower half rings with their grooves enter the pins pressed into the rear main bearing cover.

The toe and shank of the crankshaft are sealed with rubber self-clamping cuffs.

A crankshaft gear and a front counterweight are pressed onto the front end of the crankshaft, fixed with a nut, the tightening torque is 176.4 - 294 Nm (18 - 30 kgf m).

The crankshaft of YaMZ-238BE2, YaMZ-238DE2 engines has a cone at the front end. A hub is mounted on the cone, on which a liquid vibration damper and a pulley are fixed. When repairing the engine, it should be remembered that shocks and dents on the torsional vibration damper disable it, which will inevitably lead to breakage of the crankshaft. The extinguisher should be stored and transported only in a special container in a vertical position.

On YaMZ-238BE, YaMZ-238DE engines, crankshaft 238BE-1005009 (marking 238N-1005015-U), and for YaMZ-238BE2, YaMZ-238DE2 engines - crankshaft 238DK-1005009-30 (marking 238DK-1005015-30).

The crankshaft is marked in forging on the 5th cheek.

The crankshaft journals can be of two nominal sizes and therefore the following marking options and the use of the corresponding liners are possible.

Note: The letters "DK", "N", "U", "Sh", "K" and the numbers "30", "1" are branded when marking by impact.

YaMZ-236 engine crankshaft

The crankshaft of YaMZ-236NE2, YaMZ-236 BE engines is steel, made by hot stamping. The crankshaft journals are hardened with heating by high frequency currents.

The crankshaft has four main bearings and three connecting rod journals.

The latter have internal cavities closed with plugs, where the oil undergoes additional centrifugal purification. These cavities are connected by inclined channels with transverse channels in the main journals.

To balance the engine and unload the main bearings from the inertial forces of the reciprocating masses of the pistons and connecting rods and unbalanced centrifugal forces, counterweights are installed on the cheeks of the crankshaft, in assembly with which the crankshaft is balanced.

In addition, the balancing system includes two remote masses, one of which is made in the form of a tide on the flywheel, the other is a counterweight mounted on the front end of the crankshaft.

Axial fixation of the YaMZ-236 crankshaft is carried out by four bronze half-rings installed in the grooves of the rear main bearing. To prevent rotation, the lower half rings with their grooves enter the pins pressed into the rear main bearing cover.

The toe and shank of the crankshaft are sealed with rubber self-clamping cuffs.

The crankshaft 236NE-1005009 (marking 236N-1005015-U) is installed on the engines. The crankshaft is marked on the 5th cheek. The crankshaft journals can be of two nominal sizes and therefore the following marking options and the use of the corresponding liners are possible.

Dimensions of crankshafts and liners for YaMZ-236 NE2, YaMZ-236 BE engines

Crankshaft 236N -1005015-U

Diameter of root journals, mm - 110-0.022

Crankshaft 236N -1005015-U Sh1

Diameter of root journals, mm 110-0.022
Main bearing markings 236-1005170-B and 236-1005171-B
Thickness of the root bearing, mm 2.965-0.012

Crankshaft 236N-1005015-U K1

Diameter of connecting rod journals, mm 88.00-0.022
Connecting rod bearing marking 236-1004058-B
Connecting rod bearing thickness, mm 2.490-0.012

Crankshaft 236N 1005015-U Sh1K1

Diameter of main journals, mm 109.75-0.022
Main bearing markings 236-1005170-B R1 and 236-1005171-B R1
Thickness of the root bearing, mm 3.090-0.012
Diameter of connecting rod journals, mm 87.75-0.022
Connecting rod bearing marking 236-1004058-B R1
Connecting rod bearing thickness, mm 2.615-0.012

Crankshaft liners YaMZ-236NE2, YaMZ-236BE

The shells of the main bearings of the crankshaft and the lower head of the connecting rod (Fig. 5) are replaceable, thin-walled, have a steel base and a working layer of lead bronze.

Fig.5. Crankshaft bearing shells YaMZ-236

1-upper loose leaf of the main bearing; 2-lower shell of the main bearing; 3 – liners of the lower head of a rod

The upper and lower crankshaft main bearing shells are not interchangeable. The top liner has an oil supply hole and a groove for its distribution.

The connecting rod bearings are interchangeable. On YaMZ-236BE, YaMZ-236B, YaMZ-236 NE2 and YaMZ-236N engines, oil is supplied through the hole in the liner to the connecting rod upper head bushing and piston pin.

Flywheel of the YaMZ-236 engine

Flywheel YaMZ-236NE2, YaMZ-236BE is cast from gray cast iron. The flywheel is marked in a recess on the non-working surface in the casting.

The following types of flywheels can be installed on engines

Flywheel for installation on a diaphragm single-plate clutch engine:

236-1005115-K (under the ring gear with a module of 4.25);

236-1005115-N (under the ring gear with a module of 3.75).

Flywheel for installation on a dual-plate clutch engine:

236-1005115-J (under the ring gear with a module of 4.25);

236-1005115-L (under the ring gear with a module of 3.75).

All of the above flywheels assembled with gear rims are not interchangeable with each other, and flywheels 236-1005115-K and 236-1005115-Zh (under the gear rim with a module of 4.25) are mated with the starter model 2501.3708-01, and flywheels 236-1005115- N and 236-1005115-L (under the ring gear with a module of 3.75) are joined to the starter model 2501.3708-21.

The flywheel is attached to the YaMZ-236NE2, YaMZ-236BE crankshaft with bolts. A high hardness steel plate is installed under the bolts (one for all bolts). The absence of self-loosening of the bolts is ensured by a tightening torque of 235-255 Nm (24-26 kg/m).

To accurately fix the flywheel relative to the crankshaft journals, two pins are used, while the holes marked on the flywheel and on the plate must match the offset pin on the crankshaft.

The offset pin is located in the plane of the first crank. The marking on the plate in the form of a dot must be on the outside. Twelve radial holes are designed to rotate the crankshaft when adjusting the engine. Access to the holes is possible with the cover of the lower hatch of the flywheel housing removed.

Connecting rod journals of the YaMZ-236 crankshaft

Each time the crankshaft is removed from the engine to replace the liners, clean the cavities of the connecting rod journals, after removing the plugs 2 (Fig. 6), which close the cavities. Plugs must be replaced with new ones; they must not be reused.

Fig.6

Before installing the plugs, saw down the swelling of the metal at the edges of the holes from the previous centering, rinse the shaft and blow out the oil channels.

Press the plugs to a depth of 5-6 mm from the edge of the hole, then punch inside the hole at three points equally spaced around the circumference to prevent spontaneous pressing out of the plugs.

Grinding the crankshaft journals repair dimensions produce within the prescribed dimensions, while ensuring that the following requirements are met:

When regrinding the shaft necks to repair dimensions, ensure a smooth transition radius of 6-0.5 mm from the necks to the cheeks without undercuts, burns, rough scratches; the roughness of the surfaces of the necks should not exceed 0.20 microns, the radii of the fillets - 0.32 microns.

The value of the radii of the axes of all crankshaft cranks must be 70 ± 0.12 mm.

The parallelism tolerance of the axes of the middle main journals relative to the common axis of the extreme main journals should not exceed 0.010 mm, the tolerance of the parallelism of the axes of the connecting rod journals relative to the common axis of the extreme main journals should be no more than 0.03 mm over a length of 100 mm or 0.022 mm over the length of the neck.

Ovality, taper, concavity and barrel-shaped main and connecting rod journals are not allowed more than 0.005 mm.

Cracks on the surface of the crankshaft are not allowed. Check the absence of surface defects with a magnetic flaw detector with mandatory subsequent demagnetization.

Installing the YaMZ-236 crankshaft on the engine

When installing the crankshaft on the engine, ensure that the dimensions of the bearing shells match the dimensions of the shaft journals.

Before installation, ensure that the external surfaces and internal cavities of the crankshaft and other mating surfaces are clean.

Lubricate the necks and running surfaces with clean engine oil. To facilitate installation of the flywheel in correct position relative to the crankshaft, the number “6” is applied on the flywheel hub, which, during assembly, must be combined with the number “2” on the end.

Main bearing caps are not interchangeable; when installing them, make sure that the stamp on the cover matches the stamp on the block.

Start tightening the main bearing caps with the vertical bolts and tighten in two steps with a torque of 430 - 470 Nm (43 - 47 kg/cm) after re-tightening, then tighten the horizontal bolts in two steps with a final tightening torque of 90 - 120 Nm (9 - 12 kg/cm).

Before tightening the rear thrust main bearing, equalize the axial clearance, for which, slightly tightening the bolts bearing cover, move the crankshaft YaMZ-236 NE2, YaMZ-236 BE back forward in the axial direction until it stops with a crowbar, first back, then forward, aligning the position of the cover. After tightening the bolts, check the axial clearance with a feeler gauge. It should be the same on both sides of the cover.

The crankshaft gear can be replaced without removing the crankshaft from the engine. With the pulley and block front cover removed, press the front counterweight and gear with a puller.

Before installation, heat the gear and the front counterweight to a temperature of 105–155ºС and sequentially press them in until they stop using a special tool.

Piston group of the YaMZ-236NE2, YaMZ-236 BE engine

Connecting rod (Fig. 7) - steel, I-section, with an oblique connector of the lower head. The connecting rod is finished assembled with a cap, so the connecting rod caps are not interchangeable.

On the cover and the connecting rod, on the side of the short bolt, the serial number of the cylinder is stamped, and on the side of the long bolt, pairing marks are stamped in the form of a number that is the same for the connecting rod and the cover.

Replaceable liners are installed in the lower head of the connecting rod, and a steel-bronze bushing is pressed into the upper head. The sleeve is processed after being pressed into the connecting rod.

On YaMZ-236 BE2, YaMZ-236 NE2 engines, connecting rods 7511.1004045-02 (marking on the rod 7511.1004045) are installed, in which the distance between the axes of the holes in the upper and lower heads is increased by 15 mm, bevels on the upper head, the hole diameter is increased to 52 mm under the piston pin and there is no oil channel in the rod.

A steel-bronze bushing 7511.1004052-21 with an outer diameter of 56 mm is pressed into the upper head of the connecting rod.

Connecting rods 236 1004045-B3 (marking 236-1004045-B2) with an oil channel in the rod are installed on YaMZ-236 BE, YaMZ-236B, YaMZ-236 NE and YaMZ-236N engines. A steel-bronze bushing 840.1006026-10 with an outer diameter of 54 mm is pressed into the upper head of the connecting rod.

Fig.7. Connecting rod for YaMZ-236BE, YaMZ-236B, YaMZ-236NE and YaMZ-236N engines

1 – connecting rod; 2 – bushing of the upper head; 3 - cover; 4-short cover bolt; 5 - long cover bolt

Piston and piston pins

Fig.8. YaMZ-236NE2 engine piston

1-piston; 2-upper compression ring; 3-second compression ring; 4–maslosemnoe ring; 5-piston pin; 6-rings

The pistons (Fig. 8) are cast from a eutectic aluminum-silicon alloy. The piston is cooled with oil from a fixed nozzle.

The piston skirt has a recess for the cooling jet. A combustion chamber is made in the bottom of the piston. Pistons are marked in casting from the inside, on the bottom. Pistons with the following design features can be installed on engines:

Piston 7511.1004015-10 with three grooves for piston rings (two for compression and one for oil scraper). The groove for the upper compression ring is made in an insert made of heat-resistant cast iron (niresist type).

The combustion chamber is offset by 5 mm, side surface with undercut, has a displacer. On the bottom there are grooves for gas distribution valves.

Piston 238NB-1004015-B4 with four grooves for piston rings (three for compression and one for oil scraper). The groove for the upper compression ring is made in an insert made of heat-resistant cast iron (ni-resist type) in order to increase wear resistance.

The combustion chamber is offset by 5 mm, the side surface is undercut and has a displacer. The height from the bottom to the axis of the finger is increased to 100 mm. The diameter for the piston pin has been reduced to 50 mm.

Piston 238NB-1004015 is similar to the previous one, only it does not have a "ni-resist" insert for the upper compression ring. The combustion chamber is offset by 5 mm, without a displacer.

According to the diameter of the skirt, the YaMZ-236 pistons are divided into size groups:

Marking / Piston skirt diameter, mm

238NB-1004015 / 7511.1004015-10

NSA - 129.80-129.82 / 129.85-129.87

BNB - 129.82-129.84 / 129.87-129.89

WNB - 129.84-129.86 / 129.89-129.91

The size group is marked on the piston crown.

Piston pin YaMZ-236

Piston pin - hollow, floating type with a cemented outer surface.

The pin is installed in the hole in the piston. The axial movement of the pin is limited by retaining rings installed in special grooves in the piston bosses. The piston pin of YaMZ-236NE2, BE2 engines is nitrided and has an increased outer diameter.

Options Sleeve - Rings - Piston

Basic option

Sleeve - Phosphated 236-1002021-А5

Ring set - 4-ring hard chrome set (ex works)

Piston - With four grooves and with a non-resistive insert 238NB-1004015-B4

Permissible options (when repairing the engine)

Sleeve - Not phosphated 236-1002021-A

Ring set - Four-ring set with porous chrome 236-1004002-A4

Piston - With four grooves and with a non-resistive insert 238NB-1004015-B4 or without an insert 238NB-1004015

In operation, when repairing running engines, it is permissible to install new piston rings in an old cylinder liner located in good condition, while using only a set of piston rings with porous chromium 236-1004002-A4

Piston rings YaMZ-236

Piston rings are made of special cast iron, split, chrome-plated, installed in the piston grooves. Depending on the task performed in the working process, the rings have a different design and are installed on the piston as a set in a certain order.

The following sets of rings can be installed on pistons:

Three-ring kit 7511.1004002

- the first compression has a two-sided trapezium in cross section with a barrel-shaped working surface shifted down, chrome-plated with dense chrome. Ring number 7511.1004030.

− the second compression ring of rectangular section, minute, hard chrome plated. Ring number 7511.1004032.

− box-section oil scraper ring with chrome-plated working edges and coiled spring expander. Ring number 7511.1004034.

4-ring kit

- the first compression has a one-sided trapezoid in cross section. Working surface hard chrome plated. Ring number 236-1004030-B.

Four-ring kit 236-1004002-A4

- the first compression has a one-sided trapezoid in cross section. The working surface is chrome-plated with porous chrome. Ring number 236-1004030-A2.

- the second and third compression rings have a one-sided trapezium in cross section, minute. Ring number 236-1004032-A3.

− box-section oil scraper rings with chrome-plated working edges and coiled spring expander. Ring number 236-1004034.

When installing piston rings, pay particular attention to their correct position. The word "Top" should be facing the bottom of the piston.

Piston and sleeve must be selected from the same size groups to ensure a precise fit during assembly. It is allowed to install sleeve-piston kits of different size groups into different engine cylinders.

Sleeve marking - A, ANB, B

Piston marking - BNB, Zh, ZhNB

Fig.9. Piston, piston rings, YaMZ-236 finger

Left-piston 238NB-1004015-B4 rings and pin to it; on the right-piston 7511.1004015-10 rings and pin to it

Replacing piston rings

To replace the piston rings, first dismantle the piston with the connecting rod with the cylinder head and sump removed. The engines are equipped with oil-cooled pistons.

When dismantling the piston group on these engines, first remove the piston cooling nozzles in order to avoid their breakage.

For easier removal of the piston, clean the carbon deposits from the upper belt of the sleeve. Unscrew the connecting rod cover bolts, remove the cover and remove the piston assembly with the connecting rod through the cylinder.

To disconnect the connecting rod from the piston, remove the piston pin circlips, heat the piston in an oil bath to 80ºС and remove the piston pin.

To remove the piston rings, put the pliers on the ring, insert the jaws of the pliers into the lock of the ring and, squeezing the handles of the pliers to the stop, carefully remove the ring from the groove and remove it from the piston.

Install piston rings in reverse order. Carefully clean the piston from deposits, protecting it from damage (especially the end surfaces of the grooves for the piston rings).

Before assembling the piston YaMZ-236, thoroughly rinse all parts and blow out the oil channels compressed air. Assemble the piston with a finger by lightly pressing the hand, while it is necessary to generously lubricate the hole in the piston and the finger with engine oil. It is not allowed to press the finger into the piston.

In order to install the piston assembly with piston rings and connecting rod into the cylinder liner, pre-compress the rings by sinking them into the piston grooves.

To compress the rings, use a mandrel (Fig. 10) with a conical inner surface and a collar that allows the mandrel to be correctly centered on the cylinder liner. Installing the piston in the mandrel, precipitate it into the cylinder liner.

Fig.10. Mandrel for installing the YaMZ-236 piston in the cylinder liner

1 - cylinder sleeve; 2 - block of cylinders; 3 - crimping tool; 4 – piston rings; 5 - piston

When assembling the piston group and installing them on the engine, the following requirements must be met:

The piston and sleeve must be of the same size groups.

Install the compression rings with the brand "up" to the piston bottom.

Separate the locks of adjacent piston rings in opposite directions in the plane of the piston pin.

Install the piston so that the offset combustion chamber in the piston points into the engine, towards the fuel pump.

The pairing marks on the connecting rod and the cap must be the same.

Dirt, burrs and nicks on the splines of the connecting rod and the cover are not allowed.

Thread and support ends of the heads. lubricate the connecting rod cap bolts with engine oil and tighten in two steps, starting with the long bolt, first with a torque of 100 Nm (10 kg / cm), finally with a torque of 200 - 220 Nm (20 - 22 kg / cm).

The system works quite simply, especially if you consider it step by step. During the explosion-combustion of fuel in the working cavity (combustion chamber), the pressure increases many times. Since the piston in the glass is equipped with seals, then, having no outlet, the gas begins to put pressure on its plane, “squeezing” it out (“down”). Through the connecting rod, this pressure is transmitted to the connecting rod journal, and when it moves, it pulls the cheeks. Since the root neck is fixed, the cheeks do not displace it, but turn it. The result is that heat energy has become rotation.

True, here it is worth clarifying something else - due to inertia, friction and resistance to one piston or several, if all the “knees” were located in the same plane, it would be very problematic to return “to the original”. But as we have already said, there is an angular displacement of the “sets” of the cheeks-radical necks, which, coupled with the presence of counterweights and different times Ignition of the mixture gives uniform, smooth and constant rotation.

Features of YaMZash products

Depending on the purpose and specific characteristics of the internal combustion engine, the YaMZ crankshaft is made of various types steels - carbon, chromium-nickel, chromium-manganese, chromium-nickel-molybdenum and so on. It is worth remembering that in the event of a breakdown and subsequent replacement, the brand’s compliance with the standard prescribed by the automaker is a prerequisite.

In addition to the listed main components, the design of a modern crankshaft includes several more very important devices. So, remote masses are additionally arranged on the shank and toe - on the first, it is a heavy tide, on the second - the “big brother” of counterweights. All together forms a balancing system, which is subject to special requirements, therefore, before installation, the entire assembly is carefully balanced as an assembly.

Also, along the entire length, a chain of channels and ducts, complex in configuration, is being arranged, which makes it possible to provide quality lubricant all surfaces, especially friction points. Specifically, in the connecting rod journals there are enlarged cavities that serve for centrifugal oil cleaning. In the holes for the toe-shank, a seal is installed in the form of self-clamping rubber cuffs.

It should be remembered that even on the same model of the Yaroslavl motor, the base necks are produced in two different nominal diameters, respectively, the bearing shells are also used differently, and you need to carefully consider this point, since improper installation in most cases almost immediately leads to their turning. The result of such trouble - overhaul engine!

Generally, correct selection of all components and compliance with the rules of installation, as well as operation, is the key to a long service life. But we are not always the first owner of the car, which means that there is no guarantee that the previous owner did everything right. And yet, there are situations when nothing depends on us and we still have to repair the engine, for example, by replacing the liners, or even the entire crankshaft.

Trading House "SpetsMash" is a specialized enterprise whose profile is the production and sale of spare parts for heavy equipment. All our products are tested, certified in Russia products, which are covered by the official warranty from the manufacturer.

The prices are reasonable, there are variety of options savings - cumulative bonuses, wholesale discounts and so on. You can pay for the purchase in cash and by bank transfer, there are options with deferred payment. If it is impossible to independently pick up the purchase from the warehouse, delivery will be organized (to a number of cities free of charge). Communication - by phone, form on the site and E-mail.

This is an assembly of parts that has in its composition necks for fastening connecting rods, from which mechanical force is received, which is transformed into torque.

The crankshaft consists of:

• root neck,
• crankpin,
• cheeks,
• frontal output of the shaft, or toe,
• rear output shaft, or shank,
• counterweights.

At the crankshaft, the connecting rod journals are located at an angle of 90° (YaMZ-238), 120° (YaMZ-236), which ensures uniform flashes every 90° for YaMZ-238, but uneven (through 90° and 150°) for YaMZ-236

What is the function of each of the parts of the crankshaft

So, root neck- this is a support that is located in the main bearing located in the engine crankcase. The connecting rod connects the crankshaft to the connecting rods. With the help of oil channels, the connecting rod bearings are lubricated. Cheeks are needed to connect the main and connecting rod journals. The toe is the front part of the shaft, where it is fixed gear or a pulley needed to control the power of the drive of the gas distribution mechanism and auxiliary units and systems.

Shank- the back of the shaft, connected to the flywheel to control the main part of the power. Counterweights are used to unload the main bearings from the forces of inertia.

It takes the action of expanding gases during the working stroke of the pistons, which are transmitted by the connecting rods, and converts them into torque, ensures the movement of the pistons during engine start. The crankshaft is made of medium carbon alloy steels and cast iron modified with magnesium.

The shape of the crankshaft will be determined by the number and arrangement of cylinders, as well as the order of operation and the cycle of the engine. Usually, full-support are used, because the connecting rod journals are located between the main ones. Surface layer hardened to a depth of 4 mm to increase wear resistance.