Inserts indigenous for different cars: replacement, repair, installation

Turning crankshaft inserts is one of the most common serious engine failures. This does not lead to its failure, but it affects the performance. Further, the features and principles of the functioning of the inserts, as well as the replacement of the inner liners, are considered.

Definition

Root inserts are engine elements represented by plain bearings, which serve to limit the axial movements of the crankshaft and ensure the rotation of the crank journals in the cylinder block.

Principle of operation

In the design of cars used a lot of rotating elements. The ease of their rotation is ensured by the use of bearings. The most loaded rotating part of the engine is the crankshaft. Therefore, it is also installed on bearings, with the most commonly used sliding bearings. Modern parts of this type are represented by steel sheets with antifriction coating. These liners are indigenous.

Types of inserts

In addition to the indigenous there are connecting rods. It is necessary to distinguish them.

With the exception of the middle liners, they have annular grooves. Details of the middle support are wider than others. In total such inserts 10: 4 with a groove and 6 without. In the case of the block of cylinders mount loose leaves radical with grooves and one without on the third place. The remaining are mounted in the base covers.

Connecting rod diameters are smaller in diameter. They are the same in size, therefore interchangeable, and do not have annular grooves. In the connecting rod mount the liner with a hole, and in the lid without.

Features of the installation

The set of root inserts is fixed in a fixed position in special places called beds. The need for a fixed installation is explained by two factors. First, some liners have oil holes, and they need to be combined with similar channels in beds. Secondly, it allows to provide friction of details on the surfaces prepared for this purpose.

Features of operation

During operation of the engine, the liners are subjected to constant loads due to mutual friction of these parts. Therefore, the installation of the core inserts must be carried out with a reliable fixation in order to avoid their displacement by a rotating crankshaft. To this end, measures are taken:

• First, take into account the friction features of the parts in question, which manifests itself when they slide against each other under load. Its value is determined by the coefficient of friction and the value of the load on the interacting parts. Therefore, to ensure a reliable retention of the liners, it is necessary to reduce the impact on them of the crankshaft. To this end, reduce the coefficient of friction by using antifriction materials, which are applied to the surface of the liners.
• Secondly, the root inserts are mechanically held in place. Two methods are used for this. These elements are installed with the interference specified in a constructive way. In addition, each of them has an additional element, called the antenna, also serving to hold.

Dimensions

The overall parameters must be known in order to ensure the correct fit of the root inserts. The dimensions of these elements are chosen on the basis of the diameter of the bed. For this parameter, the inserts are divided into size groups, the designation of which is contained in the marking.

In size, the crankshafts are divided into nominal and repair crankshafts. There are four repair sizes with a difference of 0.25 mm. They are used if the replacement is carried out for polished crankshaft in accordance with its dimensions.

Causes of wear

As mentioned above, when the engine is running on every root liner of the engine, the frictional force constantly tends to move it from its original position. In the initial state in a serviceable engine, the strength of the parts is calculated with a margin in order to withstand such loads. For power units up to 200 liters. from. The stresses on the liner are from 0.1 to 1 kgf. The magnitude of its force is proportional to the load at a constant coefficient of friction.

In addition, the liners are protected by the fact that they function in the liquid friction regime. This is ensured by the use of oil, which creates a film between the neck of the shaft and the working surface of the liner. Thus, the parts in question are protected from direct contact, and a minimum frictional force is achieved. The formation of the oil film is determined by the speed of mutual displacement of rubbing parts. With its increase, the hydrodynamic friction regime increases. By this term is meant an increase in the efficiency of tightening the film into the gap and increasing its thickness due to this. However, as the speed of the parts increases, the amount of heat released during friction increases, and, consequently, the temperature of the oil increases. This leads to its dilution, as a result of which the film thickness is reduced. Therefore, for an optimal operating mode, it is necessary to achieve a balance between the processes considered.

In the event of a violation of the integrity of the oil film, the coefficient of friction increases. As a result, the cranking torque generated by the crankshaft increases even at a constant load.

However, sometimes there is a reverse situation, when increased loads for some reason lead to a reduction in the thickness of the oil film. As a result, the temperature rises, especially in the friction zone. As a result, the lubricant liquefies, further reducing the thickness.

These processes can be interrelated and manifest jointly. That is, one of them may be a consequence of the other.

Consequently, the viscosity of the oil significantly influences the turning moment. The relationship between these factors is directly proportional, that is, the higher it is, the greater the friction force. In addition, with a high viscosity, the oil wedge increases. However, if the viscosity is too high, the oil does not flow in sufficient volumes into the friction zone, whereby the thickness of the oil wedge decreases. As a consequence, the influence of the viscosity of the oil on the rotation of the liners can not be determined unambiguously. Therefore, take into account another property of this material: lubricity, which is understood as the strength of its adhesion to the working surface.

The coefficient of friction is determined by the roughness and accuracy of the geometry of the contacting surfaces, as well as by the presence of foreign particles in the lubricant. In the case of the presence of particles in the lubricant or surface irregularities, the film is broken, so that in some areas a semi-dry friction regime appears. Moreover, these factors are most intensively manifested at the beginning of the operation of the car, when parts are being worked in, so the rubbing parts are particularly sensitive to overloads during this period.

In addition, the crankshaft's crankshafts are cranked due to inadequate efforts to keep them in bed. It can be caused by an illiterate installation or is a consequence of wear as a result of the impact of the torque.

Checking the liners

Often there is a displacement of the root liners from the installation site crankshaft (crank). This can be caused by a decrease in the interference that holds the parts in the beds under consideration, under the influence of the factors mentioned above, and only the tendrils are not enough to hold them.

Breaking of bed liners from the bed can be determined by such factors as deaf metal knocking during engine operation and pressure drop in the lubrication system.

Repairs

To replace the core inserts, sets of wrenches and a screwdriver and a micrometer are required. Repair of the core inserts includes several operations.

• First of all, you need to provide access to the car from the bottom. That is, it should be installed above the observation pit or on the flyover.
• Remove the negative lead from the battery terminal.
• Next, dismantle the engine oil sump (this is the easiest way to access, you can start disassembling from above and hang out the engine).
• After that, the crankshaft rear oil seal holder is removed from the cylinder block.
• Then remove the camshaft drive cover with the gasket.
• Then remove the chain from the crankshaft sprocket .
• Next, you need to mark the relative position of the bearing caps relative to the cylinder block and the connecting rods relative to their covers.
• Then, using a wrench 14, unscrew the connecting rod cap nuts and disassemble it with the liner.
• These operations are repeated for all connecting rods.
• Upon completion, the covers are pushed upward.
• Then take out loose leaves radical from covers and rods.
• Then, using a key on 17, unscrew the crankshaft bearing caps.
• First, remove the lid of the last one.
• It opens access to the stubborn half-rings in the crankshaft rear crankshaft grooves. They are removed by pressing the ends with a thin screwdriver.
• These operations are repeated for the remaining bearing caps. Thus it is necessary to hold a cranked shaft. It should be noted that the lids are numbered, and the count is from the crankshaft sock.
• Then it is taken out of the crankcase.
• First, take out the connecting rod liners, and then the crankshaft crankshaft inserts.
• The crankshaft must be inspected for damage. If they are present, the detail is changed.
• Also, the conrod and base covers are examined by measuring with a micrometer. The obtained data are correlated with the tabulated data.
• If necessary, the details are polished. In this case, you will need to measure them to calculate the repair size of the inserts.
• Crankshaft is cleaned by kerosene washing and blowing cavities.
• Then, install new bearing shells.
• In the grooves of the fifth bearing bearing the thrust semirings are fixed with grooves to the crankshaft.
• Next, check the clearance between these parts. The normal value is 0.06-0.26 mm. If it is more than 0.35 mm, use rings of increased thickness.
• Crankshaft is installed in the block, pre-lubricated with oil.
• Then mount the bearing caps and check the freedom of rotation of the crankshaft.
• Connecting rods, liners and covers are installed on it.
• Then mount the oil sump.
• After that, install the crankshaft holder with the rear stuffing box.
• Finally, install the remaining parts.
• Finally, adjust the tension of the timing chain, the belt of the generator and the moment of ignition.