Moments of threads of threaded connections. How and with what force to delay the connecting rod and the root liners torque of the bolts of the covers of the indigenous bearings

The engine repair is considered in the car the most difficult, because no other item contains such a huge number of elements interrelated. On the one hand, it is very convenient, because in case of breakdowns one of them, there is no need to change the whole knot, it is enough to simply replace the detail, on the other - the more composite elements, the more difficult the device and the more difficult it is to deal with the one who is not very experienced in car repair affairs. However, with a big desire, everything is possible, especially if your zeal is supported by theoretical knowledge, for example, in determining the moment of tightening the indigenous and connecting rods. If so far this phrase for you is a set of incomprehensible words, before climbing into the engine, be sure to read this article.

Indigenous and connecting rod liners are two varieties of sliding bearings. They produced according to one technology and differ from each other only inner diameter (in the rods of rods, this diameter is less).

The main task of the liners is the transformation of translational movements (up-down) into rotational and ensuring uninterrupted operation crankshaftso that it does not wear ahead of time. It is for these purposes that the liners are installed under a strictly defined gap, which supports strictly specified oil pressure.

If this clearance increases, pressure motor oil It becomes smaller, which means that the cervicals of the gas distribution mechanism, the crankshaft, etc. important nodes wear out much faster. Is it worth saying that too strong pressure (reduced clearance) also does not carry anything positive, as it creates additional obstacles in the work of the crankshaft, he can start twisted. That is why it is important to control this gapIt is impossible without using a dynamometric key in the repair work, knowledge of the necessary parameters that are prescribed by the manufacturer in engine repair literature, as well as compliance with the moment of tightening of indigenous and connecting rod liners. By the way, the effort (moment) of the tightening of bolts of connecting rod caps and indigenous liners is different.

Please note that the standards cited are relevant only when applying new sets of parts, as the assembly / disassembly of the former node at the expense of it cannot guarantee compliance with the necessary gaps. Alternatively, in this situation, when tightening bolts, you can focus on the upper limit of the recommended point, or you can use special repair of liners with four different sizes, differing from each other by 0.25 mm, provided the crankshaft grinding until the minimum clearance between driving elements is 0.025 / 0.05 / 0.075 / 0.1 / 0.125 (depending on the existing gap and the repair used Products).

Examples of concrete moments of tightening bolts of connecting joint and indigenous liners for some cars of the VAZ family.

Video.

Engine internal combustion Constructively has a large number of conjugate parts, which are experiencing significant loads while working. For this reason, the assembly of the motor is a responsible and challenging operation, for the successful implementation of which the technological process should be observed. The functionality of the entire power unit directly depends on the reliability of fixation and accuracy of adjacent elements. For this reason an important point It is the exact implementation of the calculated conjugation between the flushing surfaces or friction pairs. In the first case, we are talking about fastening the head of the cylinder block to the cylinder block, since the bolts must be pulled out with strictly defined force and in a clearly indicated sequence.

As for loaded rubbing pairs, increased requirements are put forward to fixing connecting rod and native sliding bearings (indigenous and connecting rod liners). After repairing the engine during the subsequent assembly of the power unit, it is very important to comply with the correct torque of the indigenous and connecting rod engines. In this article we will look at why it is necessary to tighten the liners with strictly defined efforts, as well as answer the question of which moment of tightening of indigenous and connecting rod liners.

Read in this article

What are the sliding bearings

For a better understanding of why the inserts in the engine must be tightened with a certain point, let's take a look at the function and assign the specified elements. Let's start with the fact that the specified sliding bearings interact with one of the most important details of any DVS -. If briefly, the reciprocating movement in the cylinder is converted into a rotational motion precisely thanks to the crankshaft. As a result, a torque appears, which is eventually transmitted to the wheels of the car.

The crankshaft rotates constantly, has a complex shape, experiencing significant loads and is an expensive detail. To maximize the service life of the element in the design, connecting rod and indigenous liners are used. Taking into account the fact that the crankshaft rotates, as well as a number of other features, such conditions that minimize wear are created for this part.

In other words, engineers refused to solve conventional ball bearings or roller bearings in this case, replacing them to indigenous and connecting rolled sliding bearings. Indigenous bearings are used for the crankshaft root necks. Schedule liners are installed at the tent of the crankshaft crankshaft. Often the indigenous and connecting rod bearings are made according to the same principle and differ only in the inner diameter.

For the manufacture of liners, softer materials are used compared to those from which the crankshaft itself is made. Also, the liners are additionally covered with an anti-friction layer. In place where the liner is associated with the crankshaft, under pressure is served lubricant (motor oil). Specified pressure provides oil pump. It is especially important that between the crankshaft and the sliding bearing was the necessary gap. The quality of the lubrication of the rubbing pair will depend on the size of the gap, as well as the engine oil pressure indicator in the engine lubricant system. If the gap is increased, then the lubricant pressure is reduced. As a result, rapid wear of the crankshaft neck occurs, and other loaded nodes in the DVS device suffer. In parallel with this, a knock appears in the engine.

We add that the low oil pressure indicator (in the absence of other reasons) is a sign that it is necessary to grind the crankshaft, and the engine's liners themselves must be changed based on the repair size. For repair liners there is an increase in the thickness by a value of 0.25 mm. As a rule, repair sizes 4. This means that the diameter of the repair liner in the latter size will be 1 mm. less compared to standard.

Slip bearings themselves consist of two halves, in which special locks are made for proper Installation. The main task is that the clearance is formed between the neck and the liner, which is recommended by the engine manufacturer.

As a rule, a micrometer is used for measuring the neck, the inner diameter of the connecting rod liners is washed with a chute meter after assembly on the connecting rod. Also for measurements you can use control stripes of paper, uses copper foil or control plastic wire. The gap at the minimum marker for rubbing pairs should be 0. 025 mm. The increase in the gap to the indicator 0.08 mm is a reason to crowded the crankshaft before the next repair size

Note that in some cases the liners simply change to new crankshaft necks without boring. In other words, it is possible to do only to the replacement of the liners and get the desired gap without grinding. Please note, experienced professionals do not recommend this type of repair. The fact is that the resource of parts at the pairing place is greatly reduced even when we take into account that the gap in a rubbing pair corresponds to the norm. The cause is the microdefects, which still remain on the surface of the shaft neck in case of abandonment of grinding.

How to tighten the root liners and liners rods

So, taking into account the foregoing it becomes clear that the moment of tightening of the indigenous and connecting rod liners is extremely important. We now move on to the assembly process itself.

1. First of all, indigenous liners are installed in the bedside bed. It must be borne in mind that the average liner is different from others. A preservative lubricant is removed before installing bearings, after which a few engine oil is applied to the surface. After that, the lids of bed are put, after which the tightening is carried out. The tightening torque should be the one recommended for a specific model of the power unit. For example, for motors on the VAZ 2108 models, this indicator may be from 68 to 84 N · m.
2. Next, the installation of rollers inserts. During the assembly, it is necessary to accurately set the lids to the place. Specified covers are marked, that is, their arbitrary installation is not allowed. The torque of connecting rod liners is slightly less compared to the root (the indicator is within 43 to 53 N · m). For Lada Priora. The indigenous liners are delayed with force 68.31-84.38, and connecting rod bearings have a tightening torque 43.3-53.5.

It should be added separately that the specified tightening torque involves the use of new parts. If we are talking about the assembly, in which used parts are used, then the presence of production or other possible defects can lead to a deviation from the recommended norm. In this case, when tightening the bolts, you can be repelled from the top plank of the recommended point, which is specified in technical manual.

Let's summarize

Although the moment of tightening of indigenous and connecting rod bearing covers is an important parameterFrequently often in the overall technical manual for the operation of a specific TC moment value is not indicated. For this reason, it is necessary to separately search for the necessary data in the work of the repair and maintenance of one or another type of engine. It needs to be done before installing, which will allow you to perform repair work Right, as well as avoid possible consequences.

It is also important to remember that in the event of non-compliance with the recommended effort during tightening, the problem may occur both in case of insufficient moment and when tugging bolts. An increase in the gap leads to a low pressure of oil, stacks and wear. The reduced clearance will mean that in the pairing area, for example, there is a strong pressure insert on the neck, which interferes with the operation of the crankshaft and can cause it to subdinction.

For this reason, the tightening is performed using a dynamometric key and taking into account exact effort. You should not forget that the moment of tightening the bolts of connecting rod caps and the indigenous liners is somewhat different.

Read also

Why rotates crankshaft liners: the main causes. What to do if I touched the connecting roddlewill, how to change the liners of the rods.

Many motorists who are used to repairing their car themselves, do not know that the engine repair is very complex and responsible.

Since the repair of the power unit requires not only certain skills from the motorist, but also knowledge to properly implement the technological process. Today in the article we will briefly consider the crank-connecting mechanism, its role in the car engine.

In addition, we will also describe the importance of compliance with the moment of tightening of indigenous and connecting rod liners, nuances and sequences of this operation, and other important aspects. Therefore, newcomers will be useful to slightly expand their knowledge in the subject, reading our article.

The concept of CSM.

The crank-rod mechanism, abbreviated by the CSM, is for the engine the most important unit of the unit. The main task this mechanism It is a change in the straight-line movements of the piston into rotational, as well as on the contrary. This moment of rotation occurs due to the combustion of the fuel in the engine cylinders.

As is known gases during combustion fuel mixes They have an extension property. Next, they are under high pressure pushing the pistons of the engine at the bottom, and they in turn transmit force to the connecting rods and the crankshaft. It is due to the specific shape of the crankshaft in the motor there is a conversion of one movement to another, which makes it possible to edit the wheels of the machine to rotate.

According to its KSM functions is the most loaded engine mechanism. It is this node that determines, the kind will have one or another force aggregate And how cylinders will be located in it. This is due to the fact that each type of engine is created with a certain goal. In some cars, the maximum engine power is required, its low weight and dimensions, in others, in priority simplicity of maintenance, reliability and durability. Therefore, manufacturers are manufactured for different types engines different kinds Cracked connecting mechanisms. CSM are divided into single-row and double row.

The role of crankshaft liners

The crankshaft must withstand heavy loads during the engine operation. But the bearings for this device cannot be applied. This role was taken by indigenous and connecting rod liners. Although in its task they perform the functions of sliding bearings. Make inserts from a bimetallic strip consisting of low carbon steel, copper and lead, as well as alloy aluminum AFM or Babbita.

It is thanks to the liners ensures the free rotation of the crankshaft. For legends of durability and wear-resistant inserts during engine operation are covered with the finest, micron oil layer. But for their complete and high-quality lubrication, high oil pressure is simply necessary. This role on itself and took the engine lubrication system. All these conditions are just helping to reduce the friction force and an increase in the engine life.

Types and sizes of liners

In general, the crankshaft liners are divided into two groups:

1. The first type is called indigenous liners. They are between the crankshaft and the places of its passage through the motor body. They carry the largest load, since the crankshaft is fixed and spinning.
2. The second group includes connecting rod inserts. They are located between the connecting rods and crankshaft, his necks. Also carry huge loads.

Indigenous and connecting rod liners are made for each type of engine individually with their own sizes. And for the majority car engines In addition to nominal, factory sizes there are repair liners. The outer size of the repair liners remains unchanged, and the inner diameter is adjusted by increasing the thickness of the liner. There are four such size in 0.25 mm increments.

It's no secret that large runs The car wear out not only indigenous and connecting rod liners, but also crankshaft necks. These circumstances and lead to the need to replace the nominal sizes on the repair. To put this or that repair liner, the neck is mounted under a certain diameter. Moreover, the diameter is selected for each of the size of the liner individually.

If, for example, a repair size of 0.25 mm has already been applied, then when delivering from flaws on crankshaft shafts should be used in size 0.5 mm, and with serious deposits of 0.75 mm. With the correct replacement of the liner, the engine must work not one thousand kilometers, unless of course other systems of the car will be working.

There are also options when it does not require boring and liners just change to new ones. But people engaged in this professionally do not advise just to change the inserts on new ones. It is explained by the fact that during the work and operation of the inserts on the shaft, microdefects still occur, which are not visible at first glance. In general, without grinding there is a possibility of rapid wear and a small resource of KSM.

Signs of wear of the crankshaft liners

In conversations of motorists often, phrases are often sounded: "I got the engine" or "tested the liners", these words most often belong to the wear of the liners. This in turn is a serious breakdown in the motor. The first signs of such malfunctions is the loss of oil pressure or the appearance of foreign sounds when the engine is running. In the inexperienced motorist will hardly determine the signs of the liner malfunction, so it is better to immediately contact the specialists.

For a professional, listen and make a diagnosis will not make serious problems. Usually such a procedure is performed on idling The engine sharply by pressing the gas pedal. It is believed if the sound of a deaf tone or an iron grinding, then the problem is in the indigenous bearings. With problems of connecting rod liners, a call ring and stronger.

There is another way to wear wear. It is necessary to alternately unscrew the spark plugs or the nozzles in diesel engines. If, when unscrewing any candle, a knock will disappear, then this is the cylinder in which problems exist.

Problem low pressure Oil may appear not necessarily from wear of the liners. Maybe the oil pump is faulty, reduction valve Or worn bed camshaft. Therefore, first check all the nodes of the lubricant system and only after that we draw conclusions that specifically repair.

We measure the gap between the liner and crankshaft

Available inserts 2 separate parts having special places for mounting. The main task when assembling should ensure the desired gap between the shaft and the liner. Usually, a micrometer is used to determine the working gap between them, and the inner diameter of the liner is measured by the inner diameter. After that, some calculations are made, which allow to identify the gap.

However, it is much easier to make such an operation using a special plastic calibrated wire. The pieces of the desired size are stacked between the liner and the neck, after which the bearing is clamped with the desired force and disassembled again. Then the special ruler is taken, which goes in the set along with the wire, and the width of the corresponding imprint on the shaft is measured. The wider the crushed measuring strip, the smaller the gap in the bearing. This method allows you to control the desired distance between the neck and the liner with high accuracy.

How and with what force is made of indigenous and connecting rod liners?

Make a tightening of indigenous and connecting rod liners with the required effort can be a special dynamometric key. The key can be both with a ratchet, and with the arrow. On both keys there are sizes applied to it that are required for tightening nuts and bolts with any effort. To configure you, you will need to set the desired value on the key, and then you can immediately start tightening.

At the same time, remember that for the effort less than 5 kg there is no need to wear a pipe to the key to create an additional lever. This can be made with one hand to avoid breaking the thread of the bolt.

Tightening torque of indigenous and connecting rod liners

Before installing the inserts, the first thing you need to remove the preservative with lubrication and apply a small layer of oil. Next, we set the indigenous bearings in the bed of the indigenous neck, not forgetting that the average liner differs from others.

The next action will be the formulation of the lids of bed and their tightening. And the tightening torque should be applied according to the standards that are sometimes listed in the rules of operation vehicle. But most often there are cases when in the technical manual for the car does not indicate the torque of the indigenous and connecting rod liners. In such cases, it is recommended to search this information In the special literature on the repair of a particular engine. For example, for cars "Lada Priora", the moment of tightening of the bed cover is from 64 N * M (6.97 kgf * m), up to 81 N * m (8.61 kgf * m).

Next, proceed to install connecting rod liners. At the same time, attention should be paid to the correct installation of covers, each of them is marked, so do not confuse them. The tightening torque is much less than that of the root. For example, if you take the fuel model "Lada Priora", the tightening torque of rods will begin approximately with 43 N * m (4.42 kgf * m), up to 53 N * m (5.46 kgf * m).

It should be paid to the fact that the data specified for the example suggests the application for repairing new inserts, and not used parts. Otherwise, when using the previous liners, the tightening torque should be chosen, repulscing from the upper limit of the recommended point from the documentation for this engine. This is done because of the possible presence of some generation on old details. Sometimes ignoring this fact can lead to significant deviations from the recommended norm.

When the first time, all bolts will be tightened, it is advisable to make a scrolling of the shaft. To do this, on the crankshaft, there is a place for a wrench, you calmly scroll it clockwise. If the ring burst or there is any other fault, it will immediately be visible. Next, making sure that there are no problems, check again all the bolts are keys at the time of the tightening.

It should be remembered that on how correctly this process will be completed depends on the density of the adhesion of sliding bearings to the crankshaft and, accordingly, the efficiency of the engine itself. Because if you do not fully tighten the bolt, it will be an excess oil, the entire grease cycle will break, can also lead to the breakdown of the liner. If you drag, the liner will overheat, lubricants will miss already. Ultimately, the liner may also melt and turn it out that lead to overhaul Engine.

Rating 3.50.

For products from carbon steel, strength class - 2 on the bolt head, numbers are indicated via the point. Example: 3.6, 4.6, 8.8, 10.9, and others.

The first figure denotes the 1/100 nominal value of the tensile strength, measured in MPa. For example, if the marking is on the head of the bolt 10.9 The first number 10 denotes 10 x 100 \u003d 1000 MPa.

The second digit is the ratio of the flow limit to the strength limit multiplied by 10. In the above example, 9 is the yield strength / 10 x 10. Hence the yield strength \u003d 9 x 10 x 10 \u003d 900 MPa.

The yield strength is the maximum bolt workload!

Marking steel - A2 or A4 is applied for stainless steel products - and the strength of 50, 60, 70, 80, for example: A2-50, A4-80.

The number in this marking means - 1/10 correspondence to the strength of carbon steel.

Translation of units of measurement: 1 Pa \u003d 1H / m2; 1 MPa \u003d 1 H / mm2 \u003d 10 kgf / cm2.
Tightening limits for bolts (nuts).

Rough moments for tightening bolts (nuts).

The table below shows twisting moments for tightening bolts and nuts. Do not exceed these values.

The above listed values \u200b\u200bare given for standard bolts and nuts having
metric thread. For non-standard and special fasteners, see Repair Manual Repaired Technology.

Tightening torques of standard fasteners with an inch thread of the US standard.

The following tables provide general standards.
moments of tightening for bolts and SAE nuts class 5 and higher.

1 Newton meter (NM) is approximately 0.1 kgm.

ISO - International Standards Organization

Tightening torques of standard tape clamps with worm clamp for hoses

The table below gives the torque
clamps when they are initial installation on a new hose, and
also when re-installing or pulling up the clamps
on hoses, used

Tightening torque for new hoses when installing

Table of torque of typical threaded connections