A great experience in development, finishing and producing plain bearings could be seen in received patents,magazine publishings and author certificates. Most of publishings focused on plain bearings for crankshaft of diesel engines, as the most dynamic charged and basic unit which defines reliability of a power plant.

So, in this publishing [1] the experience in connecting rod bearings developing (The main Russian locomotive diesel CHN 26/26.(D49) The construction of bearings in crankshaft is used now without considerable changes.

Few publishings [2,3,4,6,8] and patents are focused on: research influence main factors on performance, consideration ways of construction, material and technology improvement. Such factors are:

  • bearing unit construction and conditions of its work, that provides resource for proper work of bearing;
  • providing necessary amount of lubricant is used for this diesel;
  • quality and stability in producing diesel units, its repairing and maintenance;
  • materials of plain bearings shells and its components that correlate to work modes of this diesel bearing. They should be reasonably priced and meet the requirements, that sometimes are contradictory. If the 2 first factors are prerogative of producer of power plant (with participation of bearings producer), then quality of details and materials are in supplier area of responsibility.

That issues are touched in program publishing [6]. There are main works that guarantee level of reliability that resulted by choosing materials and technology of production.

Necessary features bearing materials for long-term and reliable work are:

  • fatigue resistance, that means capability work properly in range of operating temperatures;
  • good tribotechnical characteristic, including low friction coefficient in conditions of mixed and boundary lubrication;
  • high resistance to score in conditions of short term breakdowns of fluid friction regime into an engine cycle or oil supplying problem;
  • high durability of bearing material, capability while emergency mode to damage and wear out crankshaft journal in a minimal way;
  • capability to embed particles in running layer of bearing without damaging surface of crankshaft journal;
  • high corrosion resistance in lubrication oil;
  • capability to adjust and compensate permissible imprecision in production and assembly;
  • technological effectiveness and reasonable production price due to using high-technology and efficient equipment and continuous production technology improvement;
  • low price of bearing materials.

It’s obvious that these requirements to bearing materials are contradictory and sometimes even mutually exclusive.

For example increasing durability and endurance is directly connected with increasing hardness. It leads to worsen its capability to adjust and retain particles without damaging crankshaft journal and necessity to harden pin surface. And from the other side materials that have perfect antifriction features - babbits (lead and tin based) have not fatigue strenght enough when engines and bearings are overloaded. The way to find bearing materials in a construction is a way of compromises for fulfil different requiremets as much as possible and with the best price.

Considering diesel bearings there are few materials that are known as right, but it’s nessessary to do research to improve them and technology of processing:

1st group of materials

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Bearings with babbit layer on bronze (or steel) basement. Babbits are made from soft allows based on tin or lead with distributed particles of more hard intermetallic compounds (Charpy rule). Such bearings are used on diesel D50 of locomotive TE3 and TE10 and as a spare its used on K6S310DR diesels of locomotive ChME3.

Babbit bearing’s advantage is low sensitiveness to lubrication breakdowns, good antifriction features and high adjustment. Its disadvantage is low fatigue strength.

High price of tin-base white metal consist of high price for nonferrous metals and its production and processing. Also, the technology and equipment are used now (babbing on bronze basement) don’t provide consistently high quality of this group bearing. We may conclude from foregoing, that main way to make price lower and increase quality and reliability of babbit bearing is decrease expense on nonferrous metals and new production technologies use.

One of such engineering solution is to make metal deposition (tin and lead) on a prefinished detail from steel – bronze strip, that are stamped and processed. Thickness after final boring should be 0.25-1,5 mm. So it’s used three-metallic bearing with babbit running layer instead of classic galvanic ternary coating.

This technology helps keep advantages of babbit bearing and produce such shells on highly productive equipment.

Second group of materials

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Bearings are made from bimetallic tape, consist of steel stripe and cladded antifriction alloy of aluminium and tin. The most popular antifriction material aluminium based is aluminium alloy with 20% of tin and 1% of copper (AO 20-1) is widely used in car engines. Its advantages are low price relative to consumer properties, good antifriction features, ecological compatibility. Disadvantages are high sensibility to deviation of geometric parameters of bearing unit. Using alloy AO20-1 without running-in layer, its sensitive to breakdown of friction modes while adjusting in uprated engines.

Shells are made from steel-aluminium tape are used as a spare parts for engines CHN 21/21(D211), 14D40 (conrod shells), M756, and for diesels D49 whom level of upgrade engine is low.

In OJS “Research Institute of Railway Transport’ important research and development are made by Doctor Bousche N. This work focused on developing shells, bearings with antifriction alloys based on aluminium. For having billets thicker, than tape is made aforesaid plants, new technology of antifriction alloy deposition by welding explosion was invented. Moreover, alloy AO 10 C2, which consist 9-12% of tin and up to 3,5% of lead was developed and patented. This alloy comparing with AO 20-1 has better durability and frictional features, but less flexible.

Test on many types of engines showed positive results. OJS “ZPS” from Tambov city increase amount of bearing production using AO10 C2, reaching 50% of all annual production in 2014.

Third group of materials

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Three-metal bearings, composed with steel-bronze base with thin running-in layer. The construction itself made in form steel basic. There is inner bronze anti-friction cover and think running-in layer is placed upon it. There is necessary note concerning its properties comparison for babbitt and aluminum covers are correlative. For new generation bearings in three-metal design this comparison is relational. In most engine bearing designs there is rule – when the worn of active layer reaching 30% of friction area the shell must be exchanged. There is arising scratching risk when there is contact with bearing’s bronze layer. According to this challenge our new design must provide high level of scratch resistance as well as bearing life time. Russian Research Railway Institute research is stating that new composed bronze alloy less tended to the scratches and this property can be developed. There is need to keep tests for checking worn and scratch resistance of different sorts of bronze compositions.

These crucial tests will also provide the basic trends developing new sorts of bronze with advanced properties for al range of technological requirements. This is crucial condition for creating new technology for cost-effective way to cover the steel billet base. This will enable us to produce good quality billet for bearing’s machine processing.

Presently the third upper layer is determine the level of load durability of bearing, not the bronze one. This bronze layer is made thing for better durability. This is also the factor which limits the bearings worn resistance.

There is need to combine high level for bearing strength with it’s worm resistance and anti-corrosion ability.

In the present period most widespread engine bearing type is steel-bronze bearing with galvanic lead-based cover. There is composition with 10-20% tin and 2-4% copper. This alloy is applied on the nickel barrier for tin diffusion prevention into bronze layer.

This construction’s level of worn and corrosion resistance can be not sufficient and can lead to bearing’s shell premature damage. Above that there is lead usage limitation according ecological requirements.

This is the reason for consistent development for new covering materials and technologies.

These is the coatings of the TIAN group (tin-antimony-copper), or Z-BHW+(tin-copper) from Companies Zollern-BHW, PVD (Physical Power Deposition). This includes coating AlSn20Cu, developed by Federal–Mogul Company, composed by vacuum spraying, as well as G 188 coating and others.

Austrian Company Miba did developed gutter type shell (rillenlager), which has periodic surface strips of soft galvanic cover and antifriction alloy.

Also, nowadays different polymeric coatings consist disulfide, molybdenum, graphite and others are widely used.

Because of necessity of creating modern Russian plain bearing production, and there are many topical problems like: creating new types of antifriction materials, coatings and technology of deposition. We together with few Russian and foreign companies solve this problems step-by-step.

It’s necessary to understand that most of developments made by foreign companies are patent-protected. So creating new ones should be as an invention and be protected by a patent.

Next important issue in providing consistency of performance, decreasing labour coefficient and increasing working efficiency is improving process of mechanic processing parts of bearing.

Major producers of tri-metal bearings use technology of one operation processing at one separate machine each surface of shell, that requires a lot of lathes, mills, grinders and other machines that generally does only 1 operation.

That’s why one of the most perspective direction of increasing quality of bearing and decreasing price is using billets with minimal allowance and new technologies using multifunctional equipment with CNC- it helps to do few processing operations on one machine.

It helps not only decrease labour coefficient and amount of equipment, but to increase efficiency of labour, accuracy of processing and provide consistency of performance which doesn’t depend on qualification or scrupulosity of worker.

Nowadays these perspective technical solutions of crankshaft bearing production are in “Leada” LLC in Kolomna.