4-26-proverka-sostoyaniya-i-podbor-vkladyshejj-korennykh-i-shatunnykh.html

4.26. Check of a condition and selection of loose leaves of radical and shatunny bearings of a cranked shaft

Condition check

In spite of the fact that bearings of a cranked shaft in the course of major maintenance of the engine are subject to replacement without fail, old loose leaves should be kept for the purpose of attentive studying of their condition which results can give a lot of useful information about the general condition of the engine. Examples of typical defects of loose leaves of bearings see above.

The exit of bearings out of operation can occur owing to a lack of greasing, hit of particles of dirt, overloads of the engine and corrosion development. Regardless of nature of defects, the reason of damage of loose leaves should be eliminated in the course of performance of major maintenance of the engine in order to avoid recurrence.

For survey take loose leaves of bearings from the beds in the engine block / the bottom heads of rods and radical / shatunny covers and spread out them as installation on a pure working surface. Organization of placement of loose leaves will allow to adhere nature of the revealed defects to a condition of the corresponding necks of a shaft.

Dirt and extraneous particles get to the engine various ways. They can be left in the block in the course of unit assembly, or get via filters or system of ventilation of a case. All particles getting to impellent oil, finally, sooner or later, appear in bearings. Often the metal sawdust which is forming in the course of normal operation of internal components of the engine takes root into a soft material of loose leaves. The probability of presence at bearings of traces of an abrasive is great, in particular, when was not given due consideration to block cleaning after completion of regenerative repair of the engine. Regardless of a way which extraneous particles get to the engine, as a result they with high degree of probability appear introduced in a soft surface of loose leaves of bearings of a cranked shaft and easily come to light at visual survey of the last. Large particles usually are not late in loose leaves, but leave on their surface and a surface of necks of a shaft appreciable traces in the form of scratches, cavities and задиров. The best guarantee from such troubles is the responsible relation to cleaning of components after completion of major maintenance of the engine and care of observance of purity at assembly. Frequent regular change of impellent oil also allows to prolong service life of bearings essentially.

Oil starvation can be a consequence of several various, but often interconnected phenomena. So, the overheat of the engine conducts to a razzhizheniye of engine oil and its replacement from working gaps of bearings. The lack of greasing of bearings can speak in excessive size of working gaps, and also usual leaks (internal or external). Often meeting reason of replacement of oil from gaps of bearings is continuous excess of turns of the engine. Passableness violation маслотоков (usually connected with the wrong combination of openings at installation of components) also conducts to reduction of supply of greasing to bearings. Typical result of oil starvation is the full or local wipe / выщербливание a blanket of loose leaves from a metal substrate. Thus the working temperature can rise to such level that the substrate as a result of an overheat gets a bluish shade.

Essential influence on service life of bearings is rendered also peculiar to the owner of the car by a driving manner. Movement with small speed on an overgear leads to considerable overloads of the bearings, being accompanied replacement of an oil film from their working gaps. Such overloads lead to increase of plasticity of loose leaves and emergence of cracks in a blanket (fatigue deformation). Thus the superficial material starts to crumble and separate from a steel substrate. Car operation in a city cycle (on short distances) conducts frequent trips to development of corrosion of bearings because the insufficient warming up of the engine involves loss of condensate and allocation of chemically aggressive gases. These products accumulate in impellent oil, forming slags and acids. At hit of such oil in bearings aggressive substances promote development of corrosion of loose leaves.

The wrong installation of loose leaves in the course of engine assembly also can be at the bottom of their fast destruction. Too hard landing does not provide the demanded size of a working gap of bearings that leads to their oil starvation. Result of hit under loose leaves (in the course of their installation) extraneous particles is formation of eminences the blanket with which is quickly wiped.

Selection of loose leaves

Radical bearings

Calculation of number of dimensional group of the loose leaf is carried out by addition to number of group of a neck of number of group of a bed. So, for example, if the neck has dimensional group "1", and a bed of the corresponding bearing — «2», it is necessary to choose the loose leaf of dimensional group "3". For definition of dimensional group of loose leaves the color code is used.

If the cranked shaft was exposed to a pro-point, it should be completed with loose leaves corresponding repair (with belittling) the sizes. Usually selection of loose leaves is carried out by the experts making a pro-point of necks of a shaft. Regardless of a technique of determination of the demanded size of loose leaves working gaps of bearings should be then are checked with application of a measuring set of Plastigage (see. Installation of a cranked shaft and check of working gaps of radical bearings).

Shatunnye bearings

The selection of shatunny loose leaves is made on the basis of determination of size of working gaps in the corresponding bearings (see Spetsifikatsiy Ustanovka of shatunno-piston assemblies and check of size of working gaps in shatunny bearings of a cranked shaft).

All bearings

Remember that in the final parameter defining correctness of selection of loose leaves, the result of measurement of working gaps in bearings is. With any questions safely address to representatives of the firm HUNDRED companies Infinitis.