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KAMAZ 740 crankshaft: device and dimensions, repair, replacement
KAMAZ 740 crankshaft: device and dimensions, repair, replacement
Anonim

KAMAZ 740 crankshaft is made of high quality steel, equipped with five main journals and four connecting rod analogues. These parts are hardened by high temperature and pressure. The elements are interconnected by special cheeks and paired dumbbells.

Repair of the crankshaft "KAMAZ 740"

Features

Oil is supplied through special holes provided in the main journals. To balance inertial effects and reduce vibration, six counterweights were installed, made by stamping, like the cheeks. There are also two additional counterweights that are pressed onto the shaft. A pressed-in ball bearing of the KamAZ 740 crankshaft is located in the bored seat of the shank. The angular placement of parts relative to the crankshaft is regulated by keys.

The uniform alternation of the working moments of the KamAZ 740 crankshaft is ensured by the location of the connecting rod journals at a right angle. A pair of connecting rods is connected to each element: for the right and left cylinder row.

crankshaft diagram"KAMAZ 740"
  1. Front counterweight.
  2. Rear analogue.
  3. Drive gear.
  4. Timing gear element.
  5. Key.
  6. Key.
  7. Pin.
  8. Jet.
  9. Unloading slots.
  10. Oil ports.
  11. Holes for oil line to crankpins.

Device

A jet is screwed into the cavity of the front nose of the assembly. Through its calibration socket, lubricant for the power reduction spline shaft is supplied to the drive part of the hydraulic coupling. The KamAZ 740 crankshaft is protected from movement along the axes by a pair of upper half rings and two lower counterparts. They are mounted so that the grooves are adjacent to the ends of the shaft.

Front and rear on the toes of the block there is an oil pump drive gear and a camshaft drive gear element. At the rear end of the part, there are eight threaded connections for fixing the torque damper. The crankshaft seal is a rubber cuff, which is equipped with an anther, located in the flywheel housing. It is made from fluororubber compound directly in the mould.

Crankshaft "KAMAZ 740"

Flywheel and necks

The main and connecting rod journals of the KamAZ 740 crankshaft are 95 and 80 millimeters in diameter, respectively. There are 8 types of restoration inserts that are used for repairs without grinding. The main bearings and connecting rod bearings are made of lead-bronze-plated and tin-plated steel strip. Earbuds at the topand bottom element are not interchangeable. From transverse and longitudinal displacement, they are fixed by ledges, which are placed in the grooves of the bearing caps and the beds of the connecting rod. These parts are marked accordingly (74-05.100-40-58 and 74-05.100-57-51). Dampers and covers are made of high-strength cast iron. They are fastened with bolts, which are fixed according to a regulated scheme. The flywheel is fixed on eight bolted studs made of alloy steel, as well as pins with a bushing. To avoid damage to the assembly, washers are placed under the bolt heads, and a corolla is located on the cylindrical surface of the flywheel.

Torque damper

The crankshaft of the KamAZ 740 engine is equipped with a vibration damper, which is fixed with eight bolts on the front toe of the block. The part includes a housing that is closed by a cover. It is mounted in the flywheel with a power reserve. base and cover joints.

A high-viscosity silicone compound works between the body and the flywheel. The liquid is dosed before fixing the cover. At the centers, the absorber is adjusted by means of a washer welded to the base. Leveling of rotational moments occurs by means of braking of the absorber frame. This energy is released as a heat flux. It should be noted that when repairing the assembly, it is forbidden to violate the integrity of the body and cover. A block with deformations becomes unusable for further use.

Crankshaft specifications"KAMAZ 740"

Connecting rod and piston group

The KamAZ 740 10 crankshaft connecting rod is made of forged steel. It is equipped with a rod with an I-beam, the head at the top is of a one-piece type, at the bottom it is made with a straight connector. The final processing of the connecting rod is assembled with a cover, which is not interchangeable for analogues. In the upper head of the part there is a bushing made of an alloy of bronze and steel, which is installed by pressing. Interchangeable tabs are mounted at the bottom.

The bottom cover is fixed with bolts and nuts that are pressed into the rod. Conjugacy marks are applied to the elements in the form of serial numbers of three characters. Also on the cover is knocked out the numbered stamp of the cylinder. The piston is cast from aluminum composition, has an insert of cast iron for the upper compression ring. Also, the piston head is equipped with a combustion chamber with a central displacer. The element is axially displaced in the direction from the valve grooves by five millimeters. The side is barrel shaped with a reduction in size around the piston pin holes.

Compression and oil scraper elements

The piston is equipped with a KamAZ 740 crankshaft oil seal, as well as a pair of compression rings and one oil scraper analogue. The distance from the bottom to the lower end of the upper groove is 17 mm. The piston part of the motors 740/11, 740/13 and 740/14 differs from each other in the shape of the sockets for the rings, therefore it is not interchangeable.

Compression elements are made of reinforced, and the oil scraper ring is made of gray cast iron. On the "engine" 740/11 configurationthe cross section of the clamps is a one-sided trapezoid. When installing, the upper inclined end is placed on the side of the piston bottom. The working barrel-shaped part of the ring is coated with molybdenum. The surface of the second compression and oil scraper ring is chrome-plated.

When installing the middle of the expander is located in a special lock. The oil scraper ring is made in a box-shaped configuration, on the 740/11 motor it has a height of 5 millimeters, and on the 740/13 and 740/14 - 4 mm.

Engine "KAMAZ 740"

Repair dimensions of the KamAZ 740 crankshaft

The tables below show the dimensions at which the restoration of parts of the assembly is allowed:

Variety

Main neck size (mm)

Cylinder Assembly Hole (mm)

RO-1

94, 7

100

RO-2

94, 5

100

P10

95, 0

100, 5

R11

94, 75

100, 5

P12

94, 5

100, 5

R13

94, 25

100, 5

PO3

94, 25

100

Nominal dimensions of the KamAZ 740 crankshaft for repair and replacementtabs:

Designation

Diameter size of connecting rod neck in diameter (mm)

Crank crank hole diameter (mm)

PO1

79, 75

85, 0

PO2

79, 5

85, 0

PO3

79, 25

85, 0

P10

80, 0

85, 5

R11

79, 75

85, 5

P12

79, 5

85, 5

R13

79, 25

85, 0

Repair Kit

The KamAZ 740 crankshaft recovery kit includes the following items:

  • piston with rings;
  • finger and locking elements;
  • cylinder sleeve;
  • sealing parts.

The cooling nozzles of the assembly are mounted in the crankcase of the cylinder block, they are responsible for the timely supply of oil from the main line at a pressure of 0.8-1.2 kg/sq.cm. The valve is usually adjusted to this value. Oil is supplied to the inside of the pistons. When assembling the engine of the 740th KamAZ, it is planned to control the nozzle tube in relation to the piston and cylinder liners, while direct contact with the first element is not allowed.

Connecting rodand the piston are connected with a floating pin. The movement of the part along the axes is limited by retaining rings, and the element itself is made of chromium-nickel alloy, the socket diameter is 22 mm. Operation of an analogue with a size of 25 mm is not allowed, as this violates the balance of the power unit.

Photo of the crankshaft "KAMAZ 740"

Recovery of the crankshaft by example

To understand the features of the repair of the node in question, we will study one of the examples of its repair. The crankshaft was taken from a decommissioned truck that carried feed. After delivery of the part, it was opened, the pallet was removed, the connecting rod, liners, and main neck were unscrewed. It turned out that tin can gaskets were installed as seals under the yoke. The liners were completely yellowed and did not represent suitable elements, since the development of working sockets was too noticeable.

We decided to remove the shaft and send it for grinding, while deformation in the form of scratches was observed on the liners. At the same time, the connecting rod journals and the shaft were in excellent condition. Indigenous analogues were brought out for a second repair. By the way, cleaning and washing the crankshaft can be effectively done in the following way:

  • connect the atomizer to the compressor;
  • pouring diesel fuel into a container;
  • clean cardboard is placed under the crankshaft;
  • wash the knot until dirty spots and chips no longer appear on the litter;
  • solar fuel is heated to a hot state, gasoline is poured into the second sprayer.

Experience has shown that such cleaningcrankshaft is very efficient and allows you to reach the level of the factory supply.

Dimensions of the crankshaft "KAMAZ 740"

Finally

KAMAZ 740 crankshafts are classically hardened by exposure to high frequency currents. The depth of the protected and treated layer is about three millimeters. This makes it possible to obtain a high hardness index at all stages of knot recovery. The specified parameter is up to 62 HRC. Recently, parts processed by nitriding have been produced. That is, the crankshaft is strengthened by a thermochemical method, which makes it possible to increase hardness, but reduces the depth of the hardened part. For example, after grinding in this way, a problem arises in the need for re-processing, which is not always relevant in the current conditions.

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