What about greases. Plastic lubricants and special fluids

30.09.2019

Greases are made up of two components: liquid base(mineral, vegetable, synthetic and other oils) and thickener(solid hydrocarbons, various salts of macromolecular fatty acids - soaps, highly dispersed silica gels and bentonites, other products of organic and inorganic origin). They contain in their composition additives that improve performance. Lubricants contain various fillers: graphite, molybdenum disulfide, powdered metals or their oxides, mica, etc. Soaps are salts of higher fatty acids, including alkali metal ions (calcium, sodium).

Grease operation

Thickener - metallic soap, forms a container for oil. Soap forms a lattice fiber frame filled with oil. The extrusion of oil from this sponge occurs under the influence of mechanical forces and temperatures. Due to the presence of a structural frame, greases behave like solids under small loads (they do not spread under the influence of their own weight, they are held on inclined and vertical planes), and under the influence of loads exceeding the strength of the structural frame, they flow like oils. However, when the load is removed, the flow of the lubricant stops and it again acquires the properties of a solid body.

Benefits of greases:

ability to be retained in leaky friction units;
performance in wide temperature and speed ranges;
better lubricity;
higher protective properties against corrosion;
performance in contact with water and other aggressive media;
great economy.

Disadvantages of greases:

poor cooling capacity;
higher tendency to oxidize;
the difficulty of feeding to the friction unit.

Depending on the thickener, there are:

calcium;
sodium;
lithium;
synthetic.

Depending on the dropping point, there are:

low temperature;
medium temperature;
high temperature.

By appointment, plastic lubricants are:

antifriction;
protective;
sealing.

Characteristics of greases:

Drop point- this is the temperature at which the first drop of oil is released from the lubricant heated under standard conditions. This temperature should be 10 ... 20 °C higher than the temperature of the friction unit. The operating range of traditional greases is from -30 °С to +140 °С. Drop point: lithium greases – +170…+200 °С, complex calcium and barium greases – +230…+260 °С. The upper temperature limit of the performance of lithium greases lies within + 110 ... + 130 ° С, and complex calcium - + 150 ... + 160 ° С.
consistency characterizes the degree of hardness of greases. It is measured with standard penetrometers by immersing a calibrated cone in the lubricant. The depth of immersion (in hundredths of a centimeter) in 5 seconds at a temperature of +25 ° C is called penetration number. The higher this number, the lower the consistency of the lubricant. A high penetration number is a soft lubricant, a low penetration number is a hard lubricant. As temperature increases, the density of greases decreases. To establish the nature of such a change, the penetration number is determined at +25 °C, +50 °C, +75 °C. To work in friction units with significant thermal fluctuations, a material with a flatter penetration curve is chosen. This indicator can be used in evaluating the uniformity of different batches of grease.
Viscosity characterizes the flow of lubricant after breaking the bonds in its structural framework as a result of applying a critical load. The viscosity of lubricants depends on temperature and on flow conditions, i.e. strain rate. With an increase in temperature and an increase in the rate of deformation, the viscosity of lubricants decreases. The viscosity of lubricants is especially sensitive to changes in the strain rate. The viscosity of the lubricant determines the conditions for refueling into friction units at low temperatures, affects the starting and steady-state shear moments of the bearings, and characterizes the pumpability through oil pipelines.
Availability of water in lubrication leads to corrosion of parts of friction units. The maximum presence of water: in calcium greases - no more than 4%, in sodium ones - no more than 0.5%, in protective ones - the presence of water is not allowed.
Evaporation is determined as a percentage of volatilized oil at a given temperature in a strictly regulated time. The loss of oil due to volatility leads to a relative increase in the thickener content in the lubricant and an increase in tensile strength, viscosity, and a change in other performance properties of lubricants.
Water resistance- the ability of lubricants not to dissolve in water, not to absorb it from the environment, not to be washed off and not to significantly change their properties upon contact with it. There is no standard method for determining water resistance. If necessary, in each individual case, a certain technique is recorded in the regulatory and technical documentation (boiling in hot water, washability from a rotating bearing or plate).
Load bearing capacity lubricating film takes into account the critical temperature of the destruction of the lubricating film, critical pressure, plasticizing effect and adhesive forces, anti-friction and anti-wear properties, extreme pressure and other characteristics. Lubricants contain surfactants in their composition, so their lubricity is much higher than filler oils. The bearing capacity of the lubricating film of lubricants in the boundary layer is evaluated according to the results of friction and wear tests, which also include the method for evaluating antiwear and extreme pressure properties on a four-ball friction machine.
Anti-corrosion properties characterize the corrosive effect of the lubricant on metals. It is determined by immersing metal plates in a lubricant, holding it at a given temperature, followed by a visual determination of the presence of traces of corrosion on the plate. The appearance of corrosion spots on the plates, their significant darkening, a change in the color and appearance of the lubricant in the zone of contact with the plates indicates insufficient anti-corrosion stability of the lubricant.
Mechanical impurities during operation of plastic lubricants are not allowed.
The presence of acids and alkalis. The presence of acids is not allowed. The optimal composition is neutral. Alkali (up to 0.2%) in the lubricant is allowed to bind acids formed during operation.

Grease types

calcium(greases) - moisture resistant, can contain up to 4% moisture, have good mechanical stability, have a low coefficient of internal friction, mixing with water, do not form an emulsion. They are used in conditions of high humidity at a temperature of -30 ... +55 ° С. Melting, they lose the water contained in them, after cooling they do not restore their physical and chemical properties.

sodium- sensitive to moisture, when combined with water, they form an emulsion and release corrosive alkalis and acids. They are used in the absence of contact with water at a temperature of -30 ... +150 ° С. They have good lubricity, good sealing properties and recover their performance after melting.

Calcium-sodium- in terms of moisture resistance and temperature range, they occupy an intermediate place. They are effective for use in conditions of low humidity at a temperature of 0 ... +110 ° C.

Lithium- based on lithium soap, which has the positive properties of calcium and sodium lubricants, but without their disadvantages. Have good lubricity, excellent temperature stability. They are used at a temperature of -50 ... +150 ° C, if water can penetrate.

Lubricants with synthetic oils– polyalphaolefins of essential and silicone oils are used as oils, which are more resistant to aging than mineral oils. Thickeners - lithium soap, bentonite. They have very low friction losses and operate at temperatures of -70…+150 °C.

A brief range of greases is given in.

Table 5.2 - Range of greases

Name	Replacement	Application area
Lubricant industrial IP-1	IP-1-L, IP-1-Z	For centralized lubrication of plain and rolling bearings, guides and other friction units, for embedded lubrication of gear couplings.
Solid oil synthetic USS-1	USS-2	For pressure lubrication of plain and rolling bearings in the cold season in high humidity conditions, for lubrication with grease fittings.
Konstalin UTS-1	UTS-2	For lubrication of sliding and rolling bearings, for chain drives in conditions that completely exclude the contact of lubrication with water, for mechanisms of blast-furnace equipment: bushings of cone control winch drums, bearings and hinges of guide devices, rolling bearings of a skip winch, for forging and pressing equipment.
Industrial and metallurgical №10		For lubrication of bronze plain bearings, work rolls of rolling stands and for other friction units operating at high loads and medium speeds.
Graphite USS-A		For lubrication of heavily loaded open gears, centralized lubrication of heavily loaded friction points. For cone control winch chains.
CIATIM 201, 202		For lubrication of sliding and rolling bearings (with rotation speed up to 3000 rpm - 201; with rotation speed up to 30000 rpm - 202).
Lithium 203, 208		For lubrication of friction units under conditions of high specific pressures (up to 500 MPa - 203; up to 2400 MPa - 208).
Rope		For lubrication of steel ropes.

Additives for plastic lubricants

Anti-corrosion- used when working in a humid environment, during conservation and storage.

Antioxidants– slow down oxidation at high temperature.

Anti-seize– compounds of phosphorus, chlorine and sulfur increase the bearing capacity of the lubricating layer, sometimes have a negative effect on bearing steel.

Grease labeling

The marking of greases is indicated by letters in the following order:

Application area:
- U - universal;
- I - industrial;
- P - rolling;
- A - autotractor;
- Zh - railway;
Group name (for universal lubricants):
- H - low temperature;
- C - medium melting point;
- T - refractory;
Brand and specific properties:
- M - frost-resistant;
- B - moisture resistant;
- Z - protective;
- K - rope.

Marking examples:

UNZ grease (universal, low-melting, protective);
grease USS-1 (universal, medium-melting, synthetic).

There are quite a lot of nodes in the car, where for separation rubbing surfaces thick, ointment-like products are used, called greases. They will be discussed.

Greases are used to reduce friction and wear of units in which forced oil circulation is impractical or impossible. For example, wheel and pivot bearings, steering and suspension joints, universal joints and splines, etc. Previously, this list was quite extensive, but today we see that the share of greases among other operating materials in a car is decreasing. The reason for this is the use of maintenance-free units based on innovative structural materials (for example, the replacement of a bushing-pin friction pair with a high-molecular rubber hinge). However, where there is no alternative to the use of ointment-like products, today the most stringent requirements are imposed on them, including environmental ones. It often happens that for each specific unit, whether it is a fifth wheel coupling or cab suspension joints, only a certain brand of operating material is recommended. How to choose the right product? This is what we have to figure out.

Both solid and liquid

Greases are intermediate in consistency between liquid oils and solid lubricants (graphites, for example). At a low temperature and no load, the lubricant retains the shape given to it earlier, and when heated and under load, it begins to flow weakly - so weakly that it does not leave the friction zone and does not seep through the seals.

The main functions of greases do not differ from those assigned to liquid oils. Everything is the same: wear reduction, scuffing prevention, corrosion protection. Specificity only in the field of application: suitability for lubrication of heavily worn friction pairs; the possibility of using in non-sealed and even in open nodes, where there is forced contact with moisture, dust or aggressive media; the ability to adhere firmly to lubricated surfaces. A very important property of greases is their long service life. Some modern products practically do not change their quality indicators for the entire period of work in the friction unit and therefore can be laid one-time, during assembly.

If we talk about the general disadvantages of ointment-like substances, then first of all you should pay attention to the lack of cooling (heat removal) and the removal of wear products from the friction zone. By the way, this is probably why some automakers, when developing such components as, for example, wheel hubs, often prefer gear oils.

The simplest grease consists of two components: an oil base (mineral or synthetic) and a thickener, under the influence of which the oil becomes inactive. The thickener is the skeleton of the lubricant. Simplistically, it can be compared with foam rubber holding liquid with its cells. Most often, calcium, lithium or sodium soaps (salts of higher fatty acids) are used as a thickener, the content of which can be from 5 to 30% by weight of the product. The cheapest are calcium greases obtained by thickening industrial mineral oils with calcium soaps - greases. Once they were so common that the word "grease" has become a common designation for grease in general, although this is not entirely correct. Greases do not dissolve in water and have very high antiwear effects, however, they function normally only in units with an operating temperature of up to 50–65 ° C, which greatly limits their use in modern cars. And the most versatile lithols are lubricants obtained by thickening petroleum and synthetic oils with lithium soaps. They have a very high dropping point (about +200°C), are exceptionally moisture resistant and work in almost any load and thermal conditions, which allows them to be used almost everywhere where grease is required.

Also, hydrocarbons (paraffin, ceresin, petrolatum) or inorganic compounds (clays, silica gels) can be used as a thickener. Clay thickener, unlike soap, does not soften at high temperatures, so it can often be found in refractory lubricants. But hydrocarbon thickeners are used mainly for the production of conservation materials, since their melting point does not exceed 65°C.

In addition to the base and thickener, the composition of the lubricant includes additives, fillers and structure modifiers. Additives are practically the same as those used in commercial oils (engine and transmission), they are oil-soluble surfactants and make up 0.1-5% by weight of the lubricant. A special place in the additive package is occupied by adhesive, that is, sticky components - they enhance the action of the thickener and increase the ability of the lubricant to stick to the metal. To insure the operation of the lubricant in the limiting thermal and load conditions, sometimes solid and oil-insoluble fillers are introduced into it - as a rule, molybdenum disulfite and graphite. These additives usually give the grease a specific color, such as silver black (molybdenum disulphite), blue (copper phthalocyanide), black (carbon-graphite).

Properties and standards

The scope of the lubricant is determined by a large set of indicators, including shear strength, mechanical stability, dropping point, thermal stability, water resistance, etc. But the role of the most important characteristics is assigned to the dropping point and the level of penetration. In fact, it is this pair that is the output parameter for evaluating lubrication.

The dropping point indicates to what extent the lubricant can be heated so that it does not turn into a liquid and, therefore, does not lose its properties. It is measured very simply: a piece of lubricant of a certain mass is heated evenly from all sides, gradually increasing the temperature until the first drop falls from it. The drip line of the lubricant should be 10-20 degrees above the maximum heating temperature of the assembly in which it is used.

The term "penetration" (penetration) owes its appearance to the measurement method - the density index of semi-liquid bodies is determined in a device called a penetrometer. To assess the consistency, a metal cone of standard size and shape under its own weight is immersed for 5 seconds in a lubricant heated to a temperature of 25°C. The softer the lubricant, the deeper the cone will go into it and the higher its penetration, and vice versa, harder lubricants are characterized by a lower penetration number. By the way, such tests are used not only in the production of lubricants, but also in the paint and varnish business.

Now about the standards. According to the generally accepted classification of lubricants, it is customary to distinguish them by scope and density. Lubricants are divided into four groups according to the scope of application: anti-friction, conservation, sealing and rope lubricants. The first group is divided into subgroups: general purpose lubricants, multi-purpose lubricants, heat-resistant, low-temperature, chemically resistant, instrumental, automotive, aviation lubricants. In relation to the transport sector, anti-friction lubricants are most widely used: multi-purpose (Litol-24, Fiol-2U, Zimol, Lita) and special automotive (LSTs-15, Fiol-2U, SHRUS-4).

To distinguish products by consistency, the American classification NLGI (National lubricating Grease Institute) is used all over the world, which divides lubricants into 9 classes. The division criterion is the level of penetration. The higher the grade, the thicker the product. Greases used in automobiles are more often classified in the second, less often in the first class. Semi-fluid products recommended for use in central lubrication systems are divided into two separate classes. They are designated by codes 00 and 000.

Previously, in our country, the name of lubricants was set arbitrarily. As a result, some lubricants received a verbal name (Solidol-S), others - a numbered one (No. 158), and others - the designation of the institution that created them (CIATIM-201, VNIINP-242). In 1979, GOST 23258-78 was introduced, according to which the name of the lubricant should consist of one word and an alphanumeric index (for various modifications). Domestic petrochemists adhere to this rule today. As for imported products, there is currently no single classification for all manufacturers in terms of performance indicators abroad. Most European manufacturers are guided by the German standard DIN-51 502, which establishes the designation of greases, which displays several characteristics at once: purpose, base oil type, additive package, NLGI class and operating temperature range. For example, the designation K PHC 2 N-40 indicates that this grease is designed for lubrication of plain and rolling bearings (letter K), contains antiwear and extreme pressure additives (P), is based on synthetic oil (HC) and refers to the second class of consistency according to NLGI (number 2). The maximum application temperature of this product is +140°C (N), and the lower operating limit is limited to -40°C.

Some of the world's manufacturers use their own designation structures. Let's say Shell's grease naming system has the following structure: brand - "suffix 1" - "suffix 2" -
NLGI class. For example, Shell Retinax HDX2 stands for Very High Performance Extremely Heavy Duty (HD) lubricant containing molybdenum disulphite (X) and an NLGI consistency grade 2.

Often on the labels of foreign products there are two designations at once: own marking and a code according to the DIN standard. By analogy with liquid oils, the most complete requirements for operating materials are reflected in the specifications of car manufacturers or component manufacturers (Willy Vogel, British Timken, SKF). The numbers of the corresponding tolerances are also applied to the lubricant label next to the designation of its operational properties, but the basic information on recommended products for use and the timing of their replacement is contained in the vehicle maintenance manual.

Lubricants from different manufacturers (even for the same purpose) cannot be mixed, as they may contain additives and other components of different chemical composition. Also, do not mix products with different thickeners. For example, when mixing cast grease (Litol-24) with calcium grease (solid oil), the mixture receives the worst performance properties. Of the automotive greases offered on the market, it is most advisable to choose those recommended by the car manufacturer.

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Plasticautomotivelubricants

Introduction

Plastic (consistent) lubricants occupy a special place in the organization of vehicle maintenance. They are, for example, the main operating material during the first maintenance. The quality of the greases used affects the service life of many vehicle parts, the reliability of its operation, as well as the cost of maintenance and repair.

1. Purpose and requirementsto plasticlubricants

To lubricate automobiles, along with liquid oils, greases are used, which are in a plastic, greasy state. They are used in such assemblies of automobiles where it is difficult to create tightness for liquid oil and it is difficult to protect the surfaces of parts from the penetration of moisture, dust, and dirt.

Greases have lower lubricating properties than liquid oils, and therefore are used where friction losses are relatively small. In some cases, grease is used only or primarily for corrosion protection.

The requirements for automotive greases follow from their purpose and are as follows:

Separate rubbing parts with a strong lubricating film to reduce wear and friction losses;

Retained in the friction nodes, not flowing out of them;

Protect rubbing parts from dust, moisture and dirt;

Do not cause corrosive wear of parts;

It is easy to press (pump) through the lubrication channels without requiring too much pressure for this;

Do not change its properties for a long time during operation and storage;

Be economical and not scarce.

2. Production of greases

The production of greases differs significantly from the production of liquid oils and basically boils down to mixing (cooking) in certain proportions of their constituent components.

The basis of any grease is liquid mineral oil (75--90%).

The quality of the oil determines the lubricating properties of the grease.

The second indispensable component of the lubricant is a thickener. Adding a thickener to a liquid mineral oil turns it into a plastic lubricant, i.e., a thick, inactive, greasy mass. Such important operational properties of plastic lubricants as temperature resistance and moisture resistance depend on the type of thickener. Thickeners are divided into non-soap and soap.

Paraffin, ceresin, petrolatum, wax, etc. are used as non-soap thickeners.

A non-soap thickened (hydrocarbon) grease has good chemical and physical stability and well protects parts from oxidation by atmospheric oxygen. At the same time, it has low lubricating and thermal properties and therefore is mainly used as a protective one (except for aluminum parts).

Most automotive greases (80%) are made with soap thickeners, which are more complex than non-soap thickeners, and can be done sequentially, when the soap thickener is made first, and then the lubricant, and more often these processes are combined.

Soap-thickener is obtained by saponification of fat with alkali.

Soap lubricants according to the type of cation are divided into calcium, sodium, lithium, barium, aluminum and others (about 10 different soaps are used, as well as their mixtures).

Depending on the composition of the fats used for the preparation of soap thickeners, lubricants are isolated on synthetic fatty acids (obtained by the oxidation of paraffins) and natural fats, as well as on industrial fatty acids (stearic, 12-hydroxy-stearic, etc.).

Complex soap lubricants, for the preparation of which soaps of higher fatty acids and salts of low molecular weight organic (sometimes mineral) acids are used, are increasingly being used.

Increasingly, inorganic products are used as thickeners - silica gel, bentonite clays and carbon black.

3. Physicochemical characteristics

The physico-chemical properties of lubricants are characterized by a number of indicators specified in standards or specifications. Most of these indicators coincide in name with those provided for fatty oils, but differ from them in quantitative values and features of test methods. The other part of the indicators is specific only for plastic lubricants.

In addition, the nomenclature of indicators of plastic lubricants varies somewhat depending on the type of lubricant.

All indicators of the physical and chemical properties of plastic lubricants are divided into two groups with some convention.

The first group of indicators characterizing the pumpability, temperature conditions for the use of a lubricant, its lubricating and protective properties include: penetration, dropping point, effective viscosity, tensile strength, colloidal stability.

The second group, which characterizes the maximum content of impurities, includes: the content of alkalis, acids, mechanical impurities, water, ash.

The effective viscosity is the viscosity of the lubricant, corresponding to the true viscosity of such a Newtonian fluid, which, for a given shear stress, has the same average strain rate (average velocity gradient). Effective viscosity characterizes the pumpability of plastic lubricants through hoses and tubes to friction units under a certain pressure, depending on the size of the hoses and tubes, and the minimum temperature at which the lubricant can be pumped. Effective viscosity also characterizes the starting properties of mechanisms. Effective viscosity is determined by automatic capillary viscometers AKV-4 or AKV-2.

The tensile strength (ultimate shear stress) shows what minimum force must be applied "to the lubricant in order to change its shape at a certain temperature and move one layer of lubricant relative to another. If the lubricant has sufficient strength at a given temperature, this means that it will be held on non-sealed friction surfaces and will not slip from vertical surfaces.The strength limit of lubricants is determined by the K-2 plastometer and the SK strength gauge.

Penetration characterizes the density (consistency) of the lubricant and is expressed in degrees, corresponding to the number of tenths of mm of the depth of immersion of the needle cone into the lubricant under the action of its own weight (150 g) for 5 s at a temperature of plus 25°C.

The softer the lubricant, the deeper the cone sinks and the higher the penetration. The best grease will be one that increases penetration less with increasing temperature.

The drop point allows you to determine at what temperature the lubricant melts and turns into a liquid, losing its lubricating properties. For reliable lubrication, the operating temperature of the mechanism must be 10--20 ° lower than the dropping point of the lubricant. A grease with a low drop point will not hold in the mechanism and will need to be replenished frequently, and a grease with an excessively high drop point will heat up the moving parts.

Colloidal stability refers to the ability of a grease to resist shedding oil. It is estimated by the amount of oil, % by weight, transferred from the lubricant to the layer of filter paper. The intensity of oil release from the lubricant increases with increasing temperature, under the influence of centrifugal forces, etc.

The metal plate corrosion test characterizes the corrosiveness of greases due to the presence of free (non-saponified) organic acids or alkalis and grease oxidation products. For testing, polished and degreased copper and steel plates are immersed in a lubricant heated to 100 ° C for 3 hours. The lubricant is considered to have passed the test if, after washing, no green, tint or shades of any color are found on the copper plates, and there are no points of corrosion on the steel plates.

The content of free organic acids in lubricants is not allowed, and the content of free alkalis is severely limited. They cause corrosion of parts, and also worsen colloidal stability, tensile strength. Determination of the content of free organic acids and alkalis is carried out by titration of hydrochloric acid lubricant solutions (in the determination of alkalis) or caustic potassium (in the determination of acids).

The water content of greases varies depending on the type of grease. Greases based on non-soap thickeners are destroyed by water, and therefore its presence is not allowed. A limited amount of water is allowed in sodium and calcium-sodium greases. In calcium greases, water enters into their structure, it serves as a stabilizer, without it the grease decomposes into oil and calcium soap, but the quantitative content of water should be limited (up to 1.5--3.0%). The water content in the lubricant is determined in a similar way to the determination of water in oil and fuel.

4. Stampsplasticlubricantsand their application

Greases used for automotive lubrication are divided into antifriction, protective and sealing greases according to their main purpose.

Anti-friction lubricants reduce wear and friction of the mating parts of mechanisms, the groups of anti-friction lubricants used are given below.

General purpose antifriction lubricants for normal temperatures (Group C) are used for friction units with operating temperatures up to 70°C. This group of lubricants includes; greases, greases AM (cardan), YANZ-2, graphite USSA, LITOL-24 and TsIATIM-201.

Solidols are produced by thickening industrial oils with calcium soaps. Fatty acids derived from natural vegetable oils (fatty grease) or synthetic fatty acids. Greases are intended for lubrication of rough and low-responsibility friction surfaces of machines and mechanisms, hand tools. Solidols are efficient for a relatively short period of time.

Press grease C used mainly for friction surfaces of the chassis of automobiles, to which it is supplied under pressure; grease C - for lubrication of rolling and sliding bearings, ball, screw and chain drives, low-speed gear reducers and other friction units. US fat grease, which is a homogeneous ointment from light yellow to dark brown, is produced in two grades: US-1 (press grease) and US-2, the performance of which is limited by the temperature range from -50 to +65 ° C. In the marking, the letters indicate: y - universal, s - synthetic, s - non-fusible medium. USSA hydrated calcium graphite grease is used for lubricating car springs, open gears, torsion bar suspensions, jack threads. In appearance, it is a homogeneous ointment from dark brown to black. It is not recommended to use greases as protective lubricants, since they contain up to 3% water, which can cause corrosion of the metal under the lubricant layer.

Grease YANZ-2 -- automobile refractory calcium-sodium is used for lubrication of wheel hub bearings, worm shaft of gearboxes, car generators, etc. In appearance, it is a homogeneous ointment from light yellow to dark brown. Can replace solidol.

Grease LITOL-24 -- universal grease based on lithium soaps of 12-hydroxystearic acid is intended for friction surfaces for which solid oils and YANZ-2 grease are recommended.

Until recently, most lithium greases were prepared with stearic acid soaps -- CIATIM-201, which is designed for friction units operating at relatively low loads and low temperatures.

Lubricants for elevated temperatures (group 0) are used for friction units with operating temperatures up to 110 ° C. This group includes lubricants: TsIATIM-202, LZ-31, 1-13.

Lubricant CIATIM-202 serves for lubrication of rolling bearings operating in the temperature range -40 -- +110°C. The grease is toxic and personal protective equipment must be used when working with it. In appearance, it is a homogeneous soft ointment from yellow to light brown.

Grease LZ-31 used for sealed rolling bearings not in contact with water, as well as for the clutch release bearing of ZIL and GAZ vehicles operating in the temperature range from -40 to +20 ° C. In appearance, it is an ointment from light brown to light yellow.

Grease 1-13 on sodium and sodium-calcium soaps is intended for lubrication of rolling bearings, propeller shaft bearings, gearbox input shaft, wheel hubs, axles and hinges of control pedals. Grease is prepared by thickening petroleum oils with sodium-calcium soap of castor oil. A variant of this lubricant is 1-LZ lubricant, which is distinguished by the presence of the antioxidant diphenylamine. Lubrication in appearance - a homogeneous ointment from light brown to brown, used at temperatures from -20 to +110 ° C

Lubricant Konstaline (1 and 2) it is made on sodium and sodium-calcium soaps, it is used for friction surfaces operating in the absence of moisture at temperatures from -20 to +110 ° C. In appearance, it is a homogeneous ointment from light yellow to dark brown.

Geared(transmission) lubricants (group T) are intended for gear and screw gears of all types. This group includes industrial calcium grease TsIATIM-208. Grease is used for lubrication of heavily loaded gear reducers operating at temperatures from -30 to +100°C. In appearance, it is a homogeneous viscous black liquid. The grease is toxic, so personal protective equipment should be used when working with it.

Frost-resistant lubricants(Group H) are designed for friction surfaces with a working temperature of 40°C and below. This group "includes greases VNIINP-257, OKB--122--7. Grease VNIINP-257 is used to lubricate ball bearings and low-power gears. The grease is frost-resistant, it is a soft black grease, application temperature is from -60 to + 150 ° C. OKB-122-7 grease is used to lubricate ball bearings and other friction surfaces operating in the temperature range from -40 to + 100 ° C. In appearance, this ointment is from light yellow to light brown.

Chemically resistant lubricants (group X) are designed for friction units in contact with aggressive media. Lubricants will lean to this group; CIATIM-205, VNIINP-279. TsIATIM-205 grease prevents sintering of fixed threaded connections operating at temperatures of -60 - +50°C. In appearance, it is a homogeneous vaseline-like ointment from white to light cream in color.

TO extreme pressure And antiwear Lubricants (Group I) include TsIATIM-203, which is used for lubrication of heavily loaded gears, worm gears, sliding and rolling bearings at temperatures from -50 to +90°C. It is a homogeneous dark brown ointment without lumps.

Protective (preservative) lubricants (group K) are designed to protect metal products and mechanisms from corrosion during storage, transportation and operation. The most common protective

the lubricant is technical petroleum jelly (UN). In terms of production, canned lubricants are second only to antifriction lubricants (about 15% of the total production of lubricants). With proper application of protective lubricants, they prevent the penetration of corrosive-aggressive substances, moisture and oxygen from the air to the metal surface, thereby preventing corrosion for 10-15 years. To improve the protective and anti-corrosion properties, special additives are introduced into the lubricants. Along with plastic protective lubricants, liquid preservation oils, film-forming inhibited petroleum compositions (FINS), mastics and some other products of petroleum origin are used. Despite the widespread use of conservation greases, they have a number of disadvantages. One of the serious ones is the greater difficulty of applying and removing them from the protected surfaces compared to liquid products. To apply or remove lubricant, it is often necessary to disassemble the mechanism, which complicates and lengthens the preservation and re-preservation of products.

5. Sealing lubricants

Sealing lubricants designed to seal gaps and crevices, movable and fixed friction units. The sealing lubricant is petrol-resistant grease (BU). With its help, connections of fuel lines, fuel pumps, valves of power supply and lubrication systems can be sealed. It contains zinc soap, castor oil and glycerin. In winter, to reduce viscosity, you can add up to 25 % alcohol.

The choice of lubricants must be made in accordance with the operating conditions of the vehicle components and the technical characteristics of the lubricants given in Table. 1.

Table 1 Main characteristics of greases

	Viscosity, Pa-s, at temperature	Application temperature, °С

Solidol C			-30 to +60
Press grease C			-40 to +50
Graphite USSA			-20 to +60
			-30 to +100
CIATIM-201			-60 to +90
CIATIM-202			-40 to +110
CIATIM-203			-50 to +100

			-40 to +120
Con Stalin 1			-20 to +110
Koi [bed 2			-20 to +110
VNIINP-257	at -50 "C - 200
			from ^40 to +130

6. Determining the quality and grade of greases

The need to determine the brand of grease in the automotive industry is quite common, since the range of lubricants used is large, and they differ little in appearance. Using features such as color, moisture resistance, solubility in gasoline and grease stain, you can determine the type of grease, and in some cases approximately its specific brand.

The color can be a good indication for graphite grease, which is dark brown to black, and to some extent for technical petroleum jelly, which is light brown to dark brown and transparent in a thin layer. The rest of the greases can have a color from light yellow to dark brown and cannot be distinguished by this feature.

Moisture resistance makes it possible to distinguish greases and technical vaseline from other lubricants and, above all, from constantins. When rubbing lubricants with a small amount of water with fingers, solid oils and technical petroleum jelly (moisture-resistant lubricants (do not soap or wash off).

Solubility in gasoline makes it possible to distinguish non-soap thickened greases (protective greases) from soap thickened greases (anti-friction greases). Non-soap thickened grease, mixed with four times the amount of gasoline and heated to 60 ° C, dissolves and turns into a transparent solution, and soap thickened grease does not dissolve.

The grease stain formed on the filter paper from the application of a lump of grease to it can serve as a sign to determine its type. Grease-lubricated filter paper is heated over some kind of heat source, which melts the grease completely or partially, forming an oil slick. Technical petroleum jelly melts completely, leaving a uniform yellow spot. Graphite grease forms a dark spot with clearly visible inclusions of graphite. Greases leave a spot with a soft residue in the center, usually the same color as the spot. Constantine and calcium-sodium lubricants form a spot of smaller diameter and remain partially on the paper in an unmelted form and with intense heating until the paper is charred.

According to physical and chemical properties, lamellar lubricants entering the fleet must fully comply with the relevant standards or technical conditions.

In appearance, the grease should be a homogeneous mass without the presence of lumps, impurities, impurities or released oil. Lubricants that do not meet these conditions must be rejected.

To check for abrasive impurities, a lump of lubricant is rubbed between two glasses or between fingers. Mechanical impurities are also detected by melting a lump of lubricant on filter paper.

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Initial data…………………………………………..…………..3

List of sheets of the graphic part……………………...........4

INTRODUCTION…………………………………………………………..……......5

1.PERFORMANCE PROPERTIES OF GREASES……9

1.1. Dropping point………………………………….…………..9

1.2. Mechanical properties………………………………………….…..…..9

1.3. Effective viscosity………………………………………………….10

1.4. Colloidal stability……………………………………………………………11

1.5. Water resistance…………………………………………………………..11

2. CLASSIFICATION AND APPLICATION OF GREASES…..12

2.1. General purpose lubricants……………………………………………...13

2.2.Universal greases………………………………………………….….13

2.3.Specialized lubricants…………………………………………...14

2.4.Heat-resistant lubricants……………………………………………….…...14

2.5.Frost-resistant lubricants……………………………………………...…...15

3. CHIMMOTOLOGICAL MAP………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

4. TABLE OF REFILLING CAPACITIES………………………………22

5.List of USED literature…………………....…….23

Initial data

Option	Bus brand	operating material	group student
	PAZ - 3205	Grease	Timofeev Vladislav Valerievich

LIST OF SHEETS OF THE GRAPHIC PART

INTRODUCTION

The correct choice and rational use of operational materials largely determine the reliability and durability of equipment, the cost of its maintenance and repair. The wrong choice of engine oil can lead to shortened engine life at best, to engine failure at worst.

The choice and proper use of oil is often complicated by the fact that the technical documentation for some machines provides for a large number of brands of lubricants. Therefore, their unification and the use of substitutes can be of great importance to simplify the operation of automotive equipment.

The car has a large number of components and mechanisms where greases are used, the variety of which also implies their competent use.

To lubricate a number of mechanisms and parts of the car, thick, ointment-like products are used - greases. According to one of the terminological definitions, reflecting the volumetric mechanical properties, a grease is a system that, under low loads, exhibits the properties of a solid body; at a certain critical load, the lubricant begins to plastically deform (flow like a liquid) and, after the load is removed, again acquires the properties of a solid body.

Lubricants are complex substances in their composition. In the simplest case, they consist of two components - an oil base (dispersion medium) and a solid thickener (dispersed phase). Combining the properties of a solid and a liquid, greases can be roughly represented as a piece of cotton wool soaked in oil. Wool fibers correspond to the particles of the dispersed phase, and the oil held in the cotton wool corresponds to the dispersion medium of the lubricant.

The properties of a solid body give the lubricant the presence of a structural framework. When the loads are small, for example, under the action of its own weight, the structural frame and the lubricant itself do not collapse, but elastically deform. This is due to the nature of the thickener size, shape, nature of the adhesion of the particles of the dispersed phase.

The structural frame of the lubricant does not differ in any significant strength. Even the application of small loads destroys it, and the lubricant deforms like a plastic-viscous fluid. Thanks to this, the lubricant can be used in the friction unit, freely applied to surfaces protected from corrosion.

The process of destruction of the structural framework of greases is reversible. After the load is removed, the flow of the lubricant stops, the structural frame is almost instantly restored, and the lubricant again acquires the properties of a solid body.

Various oils of petroleum and synthetic origin are used as the oil base of lubricants. Thickeners that form solid particles of the dispersed phase can be substances of organic and inorganic origin (fatty acid soaps, paraffin, heat-resistant materials such as silica gel, bentonite, carbon black, organic pigments, etc.).

Greases are intended for use in friction points where oil is not retained or where continuous oil replenishment cannot be ensured.

1.PERFORMANCE PROPERTIES OF GREASES

1.1 Dropping point

In a grease when heated, an irreversible process of destruction of the crystalline framework occurs, and the grease becomes fluid. The transition from a plastic state to a liquid state is conditionally expresseddropping point, i.e. the temperature at which the first drop of lubricant falls from a standard device when heated.The dropping point of lubricants depends on the type of thickener and its concentration.

According to the dropping point, lubricants are divided into refractory (T), medium-melting (C) and low-melting (H). Refractory greases have a drop point above 100 °C; low-melting - up to 65 ºС. In order to avoid leakage of lubricant from the friction unit, the dropping point should exceed the temperature of the working unit by 15-20 ºС.

1.2 Mechanical properties

The mechanical properties of lubricants are characterized by the shear strength of lubricants and penetration.

Tensile strength is the minimum specific stress that must be applied to the lubricant in order to change its shape and move one layer of lubricant relative to another. At lower loads, greases retain their internal structure and deform elastically like solids, while at high pressures, the structure breaks down and the lubricant behaves like a viscous liquid.

The tensile strength depends on the temperature of the lubricant - it decreases with increasing temperature. This indicator characterizes the ability of the lubricant to be retained in friction units, to resist discharge under the influence of inertial forces. For operating temperatures, the tensile strength should not be lower than 300500 Pa.

Penetration is a conditional indicator of the mechanical properties of lubricants, numerically equal to the depth of immersion of the cone of a standard device in them for 5 s. Penetration is a conditional indicator that has no physical meaning and does not determine the behavior of lubricants in operation. At the same time, since this indicator is quickly determined, it is used in production conditions to assess the identity of the formulation and adherence to the lubricant manufacturing technology.

The penetration number characterizes the density of lubricants and ranges from 170 to 420.

1.3 Effective viscosity

The viscosity of the lubricant at the same temperature can have a different value, which depends on the speed of movement of the layers relative to each other. As the travel speed increases, the viscosity decreases as the thickener particles are oriented in the direction of travel and offer less slip resistance. An increase in the concentration and degree of dispersion of the thickener leads to an increase in the viscosity of the lubricant. The viscosity of the lubricant depends on the viscosity of the dispersed medium and the technology for preparing the lubricant.

The viscosity of a lubricant at a certain temperature and travel speed is called the effective viscosity.and is calculated by the formula

where shear stress; D shear rate gradient.

The viscosity index is of great practical importance. It determines the possibility of supplying lubricants and refueling to friction units using various filling devices. The viscosity of the lubricant also determines the energy consumption for its pumping when moving lubricated parts.

1.4 Colloidal stability

Colloidal stability is the ability of a lubricant to resist segregation.

Colloidal stability depends on the structural skeleton of the lubricant, which is characterized by the size, shape and strength of the bonds of structural elements. Consequently, the viscosity of the dispersion medium affects the colloidal stability: the higher the viscosity of the oil, the more difficult it is for it to flow out.

The release of oil from the lubricant increases with increasing temperature, increasing pressure under the action of centrifugal forces. A strong release of oil is not permissible, as the lubricant may degrade or completely lose its lubricating properties. To assess colloidal stability, various instruments are used that are capable of extruding oil under load.

1.5.Water resistance

Water resistance is the ability of a lubricant to resist water washout. The solubility of a lubricant in water depends on the nature of the thickener. Paraffin, calcium and lithium greases have the best water resistance. Sodium and potassium are water-soluble lubricants.

2. CLASSIFICATION AND APPLICATION OF GREASES

Greases are divided into four groups:

Antifriction - to reduce wear and sliding friction of mating parts;

Conservation - to prevent corrosion during storage, transportation and operation;

- rope - to prevent corrosion and wear of steel ropes;

Sealing - for sealing gaps, facilitating the assembly and disassembly of fittings, cuffs, threaded, detachable and any movable joints.

Anti-friction lubricants arethe largest group of plastic lubricants and are divided into the following subgroups:

C - general purpose;

O - for elevated temperature;

M - multi-purpose;

Zh - heat-resistant (friction units with operating temperature >150 °C);

H - low-resistance (friction units with operating temperature<40 °С);

And - extreme pressure and antiwear;

X - chemically resistant;

P - instrument;

T - gear (transmission);

D - running-in pastes;

Y - highly specialized (industry).

Preservative lubricants are designated by the letter “3”, cable “K”.

Sealing lubricants have three subgroups:

A - reinforcing (for cuffs);

R - threaded;

B - vacuum (for seals in vacuum systems).

Depending on the application, lubricants are divided into general purpose, multi-purpose and specialized.

2. 1 .Greases for general use

Calcium greases have a common name greases. These are the most popular and cheapest anti-friction lubricants, they are non-fusible media. Calcium lubricants are available in the following grades: Solidol Zh, Pressolidol Zh, Solidol S or Pressolidol S.

Solidol C is operational at temperatures from -20 to 65 ° C. Pressolidol C - from -30 to 50 °C.

Sodium and sodium-calcium greases operate in a wider temperature range (from -30 to 110 °C) and are mainly used in rolling bearings.

For example, YANZ-2 automotive lubricant is almost insoluble in water, but emulsifies with prolonged use in a humid environment. It is replaced by the universal grease Litol-24.

2.2.Universal lubricants

Universal lubricants are water-resistant and workable in a wide range of temperatures, speeds and loads. They have good preservation properties. Lithium soaps serve as thickeners for them.

Litol-24 - can be used as a single automotive lubricant, it is efficient at temperatures from -40 to 130 ° C.

Fiol-1, Fiol-2, Fiol-3 - lubricants are similar to Litol-24, but softer, better retained in friction units.

2. 3 .Specialized lubricants

Specialized lubricants include about 20 brands of lubricants of different quality. They are most effectively used as non-replaceable and non-refillable lubricants during operation.

Graphite - used mainly in open nodes.

AM cardan - for cardan joints of equal angular velocities (Tract, Rcepp, Weiss) of trucks, prone to leakage from nodes.

SHRUS-4 - for constant velocity joints (Birfield type) of cars; Operable at temperatures from -40 to 130 ° C, water-resistant, has high extreme pressure and anti-wear properties.

ShRB-4 - for sealed suspension and steering joints, operating temperature range from -40 to 130 °C.

LSTs-15 - used in splines, hinges and axles of pedal drives, power windows; possesses high water resistance, adhesion (stickiness) to metals, good conservation properties.

2.4. Heat-resistant lubricants

Limit of performance of heat-resistant lubricants from 150 to 250 °C.

Uniol-ZM is water-resistant, has good colloidal stability and extreme pressure properties.

CIATIM-221 - can be used at temperatures from -60 to 150 ° C, chemically stable to rubber and polymeric materials.

2.5.Frost-resistant lubricants

Frost-resistant lubricants are efficient in all friction units in the conditions of the Far North and the Arctic.

Zimol is a frost-resistant analogue of Litol-24 lubricant.

Lita is a multi-purpose frost-resistant working and conservation lubricant, waterproof.

CIATIM-201 - the main frost-resistant lubricant for cars, has mediocre extreme pressure properties, releases oil during storage. Zimol and Lita, inferior to it in frost resistance, are superior in anti-wear properties, performance at elevated temperatures.

3.CHIMMOTOLOGICAL MAP

Table 1.

pos. no. on the lubrication diagram

Name of the node, unit

Lubrication quantity (total for all points)

Grease name

Number of points

Periodicity

Lubrication instructions

TO-1

TO-2

ONE HUNDRED

Brake Pedal Drive Roller

Lubricate with a grease fitting

Power steering system

2.5 l

MG-15-V GOST 17479.3-85

X XX

Check the oil level in the reservoir and top up if necessary. When using substitutes, change the oil at the service station, wash both pump filters in gasoline or kerosene. Replace filter element

Brake Master Cylinder Fill Tank

0.6 l

Brake fluid "Rosa" TU 2451-004-10488057-94 Substitutes: "Neva", "Tom" TU 6.01.1163-78, TU 6.01.1276-82, SAE 1703F;
DOT-4

Continuation of table 1.

Engine oil crankcase	10 l			Check the oil level at EO, top up to the correct level. Change oil and oil filter element
Water pump bearings		Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3
Crankcase ventilation oil separator			XX	Disassemble, wash in kerosene, wipe dry, reinstall
Fan idler bearings		Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3	X XXX	Apply grease to the bearing cavity. Remove roller, wash in kerosene, wipe dry and apply fresh lubricant
Fan shaft bearings		Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3		Lubricate through the grease fitting until fresh grease comes out of the control hole.

Continuation of table 1.

Radiator shutter rollers	3 g	Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate the roller axles once a year - in autumn
Ignition distributor: - rotor sleeve		М-4з/6-В1 GOST-17479.1-85 Duplicating: SAE 5W-30, SAE 5W-40			4 - 5 drops
Front axle wheel bearings	1 kg	Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3	XX		Apply grease with the hub removed between the rollers and separators evenly over the entire internal cavity of the bearings
Clutch Release Bearing	30 g	Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate with one full fill of cap oiler
gearbox housing	3 l	TM-5-18 GOST 17479.2-85 Substitute: SAE 85W/90 per API GL-5		XX	Check oil level, top up if necessary. Change lubricant.
Cardan shaft joints	50 g	Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate every two years
The bearing of a support of an intermediate shaft of cardan transfer	50 g	Litol-24 GOST 21150-87			Lubricate through the grease fitting until fresh grease comes out of the control hole.
Cardan shaft splines	240 g	Litol-24 GOST 21150-87 or YANZ-2 GOST 19537-74			Lubricate through a grease fitting (10 strokes with a syringe)

Continuation of table 1.

Battery terminals and jumpers		Litol-24 GOST 21150-87 or CIATIM-201 GOST 6267-74			Apply a thin layer
rear axle housing	8.2 l	TM-5-18 GOST 17479.2-85 or Top75W-85 SKG-F		XX	Change oil
Air brake booster filters		Oil M-8V GOST 10541-78	XXX		Rinse the filter elements in kerosene and dip in clean oil
Frost protector	200 g	Ethyl alcohol technical GOST 17228-78			Use at ambient temperatures below 5°C
Tie rod joints		Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate until fresh lubricant appears
Steering knuckle pins	0.09 kg	Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate through a grease fitting four piles at each point
Power Steering Cylinder Hinges Cylinder Support		Litol-24 GOST 21150-87 Substitute: Lithium grease according to NLGJ No. 3			Lubricate until fresh grease comes out of the hole. Disassemble, lubricate

Continuation of table 1.

Clutch release reservoir

0.45 l

Tom
TU 2451-004-
10488057
or SAE 1703F;
DOT-4

Check the fluid level and, if necessary, top up (do the same after pumping and repair work). Change the fluid once a year in the fall

3.1. Chemotological map of fuels and lubricants and special fluids used as needed and during repair work

Table 2.

pos. no. on the lubrication diagram	Node name	Quantity of grease	Grease name	Lubrication instructions

	Shift Lever Sphere Bracket	0.05 kg	Litol-24 GOST 21150-87, NLGJ Lithium Grease #3	Lubricate as needed
	shock absorbers	1.9 l	GTZh-12 GOST-23008-88	Replace when repairing
	Spare wheel mechanism	0.015 kg	Litol-24 GOST 21150-87, NLGJ Lithium Grease #3	Lubricate the drum axle during repairs
	Rod and pusher of pneumatic amplifiers	0.015 kg	Litol-24 GOST 21150-87, NLGJ Lithium Grease #3	Lubricate as needed
	Driver door lock	0.005 kg		Lubricate as needed when repairing or disassembling
	Parking brake actuator	0.010 kg	Litol - 24 GOST 21150-87	Lubricate as needed
	Driver door hinges	35 g	Litol - 24 GOST 21150-87 CIATIM - 201 GOST 6267-74	Lubricate as needed
	Steering column bearing	0.05 kg	Litol - 24 GOST 21150-87

Continuation of table 2.

Steering column universal joint

0.015 kg

Litol-24
GOST 21150-87,
NLGJ Lithium Grease #3

Lubricate as needed and when repairing

4.TABLE OF REFILLING CAPACITIES

Table 3

System, mechanism, unit	Volume, l	Operating materials
Fuel tank		AI-91, AI-92
Cooling system		Tosol A-65M
Lubrication system (excluding oil cooler)		M-4z/6-B1
gearbox housing		TM-5-18
rear axle housing		TM-5-18
Shock absorbers (each)	0,475	GTZh-12
Service brake hydraulic drive system	0,75	Rosa, Neva, Tom
Power steering		MG-15-V
Front wheel hub (each)		Litol-24
Windshield washer		Ethyl alcohol technical
Clutch Master Cylinder Fill Tank	0,45	Rosa, Neva, Tom

5. LIST OF USED LITERATURE

1. Stukanov V.A. Automotive operating materials. M.; FORUM: INFRA-M, 2003 - 208 p.

2. Vasilyeva L. S. Automobile operating materials. M.: Transport, 1986 280 p.

3. Buses of the PAZ-3205 family: design features, operation and maintenance manual, Pavlovo-on-Oka. 2006 113 p.

Oil	Transmission type	Oil change period, thousand km	Minimum application temperature, °C
TSgyp	Drive axles of old car models	24...30	-20
TAD-17I	Gearboxes and drive axles for cars and trucks	60...80	-30
TAp-15V	Gearboxes for trucks with carburetor engines; drive axles with non-hypoid gears for cars and trucks	24...72	-25
TSp-15K	Gearboxes, drive axles of trucks with non-hypoid gears	36...72	-30
TSp-14gip	Driving axles of trucks with hypoid gears		-30
TSp-10	Gearboxes for trucks with carburetor engines; drive axles of trucks with non-hypoid gears	35...50	-45
TSz-9gip	Gearboxes and drive axles of vehicles during operation in the North	winter period	-50
TM5-12rk	Gearboxes and drive axles of trucks		-50

Abroad, for marking gear oils, the SAE and API classifications are used.

According to the SAE classification, oils are divided into summer (for example, SAE140), winter (75W) and all-weather (75W90). The correspondence of viscosity classes according to GOST and SAE is given in Table. 23.

Table 23

Approximate correspondence of viscosity grades of gear oils according to GOST and SAE

According to the API classification, gear oils are classified according to the level of anti-wear and extreme pressure properties:

GL-1 - used in gears at low pressures and sliding speeds (do not contain additives);

There are 5 classes in total, which correspond to the groups designated according to GOST TM-1, -2, -3, -4, -5.

Greases are used to reduce friction and wear of units in which forced oil circulation is impractical or impossible. Easily penetrating into the contact zone of rubbing parts, lubricants are held on rubbing surfaces without dripping from them, as is the case with oil. Lubricants are also used as protective or sealing materials.

Advantages and disadvantages of lubricants

The advantages include the ability to be retained, not to flow out and not to be squeezed out of non-sealed friction units, a wider temperature range of application than that of oils. These advantages make it possible to simplify the design of friction units, therefore, to reduce their metal consumption and cost. Some lubricants have good sealing ability and good preservation properties.

The main disadvantages are the retention of mechanical and corrosive wear products, which increase the rate of destruction of rubbing surfaces, and poor heat removal from lubricated parts.

Composition of plastic lubricants. Oil is the basis of lubrication, and it accounts for 70-90% of its mass. The properties of the oil determine the basic properties of the lubricant. The thickener creates a spatial skeleton of the lubricant. Simplistically, it can be compared with foam rubber holding oil in its cells. The thickener is 8-20% by weight of the lubricant.

Additives are needed to improve performance properties. These include:

Additives - mostly the same as those used in commercial oils (motor, transmission, etc.). They are oil-soluble surfactants and make up 0.1-5% by weight of the lubricant;

Fillers - improve anti-friction and sealing properties. They are solid substances, as a rule, of inorganic origin, insoluble in oil (molybdenum disulfide, graphite, mica, etc.), make up 1-20% by weight of the lubricant;

Structure modifiers - contribute to the formation of a stronger and more elastic lubricant structure. They are surfactants (acids, alcohols, etc.), they make up 0.1-1% by weight of the lubricant.

The main indicators of the quality of lubricants

Penetration (penetration) - characterizes the consistency (thickness) of the lubricant by the depth of immersion of a cone of standard sizes and weight into it. Penetration is measured at various temperatures and is numerically equal to the number of millimeters of cone immersion multiplied by 10.

Drop point - the drop temperature of the first drop of lubricant heated in a special measuring device. It practically characterizes the melting temperature of the thickener, the destruction of the lubricant structure and its leakage from the lubricated units (it determines the upper temperature limit of performance not for all lubricants).

Shear strength is the minimum load at which an irreversible destruction of the lubricant framework occurs and it behaves like a liquid.

Water resistance - in relation to greases, it means several properties: resistance to dissolution in water, the ability to absorb moisture, the permeability of the lubricating layer for moisture vapor, and washability with water from lubricated surfaces.

Mechanical stability - characterizes thixotropic properties, i.e. the ability of lubricants to almost instantly restore their structure (framework) after leaving the zone of direct contact of rubbing parts. Due to this unique property, the lubricant is easily retained in non-sealed friction units.

Thermal stability - the ability of a lubricant to maintain its properties when exposed to elevated temperatures.

Colloidal stability - characterizes the release of oil from the lubricant during mechanical and thermal effects during storage, transportation and use.

Chemical stability - characterizes mainly the resistance of lubricants to oxidation.

Evaporation - evaluates the amount of oil evaporated from the lubricant in a certain period of time when it is heated to the maximum application temperature.

Corrosiveness - the ability of lubricant components to cause corrosion of the metal of friction units.

Protective properties - the ability of lubricants to protect the rubbing surfaces of metals from the effects of a corrosive external environment (water, salt solutions, etc.).

Viscosity - is determined by the values of losses due to internal friction in the lubricant. In fact, it determines the starting characteristics of mechanisms, the ease of feeding and filling into friction units.

Greases are intermediate in consistency between oils and solid lubricants (graphites). Despite the absence of other lubricant characteristics as criteria for classifying, this classification is recognized as fundamental in all countries. Some manufacturers indicate in the documentation not only the class of lubricant, but also the level of penetration.

Greases (PS) are thick, ointment-like products. They have two main components - an oil base (dispersion medium) and a solid thickener (dispersion medium). To improve the conservation, anti-wear properties, chemical stability, and thermal stability, additives are introduced into lubricants in the amount of 0.001 ... 5%.

It should be noted that not all of the following classifications are generally accepted for domestic and foreign manufacturers.

The classification designation indicates:

dispersion medium;

consistency.

The thickener is indicated by the first two letters of the metal included in the soap: "Ka" - calcium; "On" - sodium; "Li" - lithium.

The type of dispersion medium and the presence of solid additives are denoted by lowercase letters: "y" - synthetic hydrocarbons, "k" - organosilicon liquids, "g" - graphite additives, "e" - molybdenum disulfite additive. Petroleum based lubricants do not have an index.

Classification by type of oil (base):

On petroleum oils (obtained by oil refining);

On synthetic oils (artificially synthesized);

On vegetable oils;

On a mixture of the above oils (mainly petroleum and synthetic).

Classification by the nature of the thickener.

Soaps are lubricants for the production of which soaps (salts of higher carboxylic acids) are used as a thickener. In turn, they are divided into sodium (created in 1872), calcium and aluminum (created in 1882), lithium (created in 1942), complex (for example, complex calcium, complex lithium), etc. Soaps account for more than 80% of all lubricant production.

Hydrocarbon - lubricants, for the production of which paraffins, ceresins, petrolatums, etc. are used as a thickener.

Inorganic - lubricants, for the production of which silica gels, bentonites, etc. are used as a thickener.

Organic - lubricants, for the production of which carbon black, polyurea, polymers, etc. are used as a thickener.

Classification according to the field of application in accordance with GOST 23258-78 divides lubricants into the following groups.

Antifriction - reduce the friction force and wear of various rubbing surfaces.

Conservation - prevent corrosion of metal surfaces of mechanisms during their storage and operation. Conservation - designed to prevent corrosion of metal surfaces during storage and operation, designated by the index "Z".

Sealing - seal and prevent wear of threaded connections and shut-off valves (valves, gate valves, taps). Sealing are divided into three groups: A - reinforcing; P - threaded; B - vacuum.

Rope - prevent wear and corrosion of steel ropes. Rope lubricants are indicated by the index "K".

In turn, the antifriction group is divided into subgroups: C - general purpose for temperatures up to 70 ° C, O - for elevated temperatures (up to 110 ° C), M - multi-purpose (-30 ... 130 ° C); Zh - heat-resistant (150 "C and above), H - frost-resistant (below -40 0 C); I - extreme pressure and anti-wear; P - instrument; D - running-in; X - chemically resistant.

Example. PS Litol-24 (trade mark) has the following classification designation MLi4/13-3: "M" - multi-purpose anti-friction, operable in conditions of high humidity; "Li" - thickened with lithium soaps; "4/13" - operable in the temperature range from -40 to 130 "C, no dispersion medium index - prepared in petroleum oil; "3" - conditional characteristic of the lubricant density.

Calcium greases (greases) - anti-friction plastic lubricants. They are insoluble in water, therefore, in conditions of high humidity and in contact with water, they well protect metal parts from corrosion. The disadvantage is that they are efficient at temperatures up to 60 0 С.

Solid oils synthetic (solid oil C) - used in rolling and sliding bearings, in hinges, screw and chain drives. Their disadvantages are low mechanical stability, performance at temperatures up to 50 °C.

Application

Litol-24 is used in steering joints, pivot pins, spring pins, clutch and brake pedal axles, gear levers, transfer case, brake expander shafts, winch mechanisms, towing and saddle mechanisms, splines and bearings of cardan joints, Litol-24, grease C, press grease C.

For cardan joints of equal angular speeds, AM cardan, Uniol-1 is used.

Wheel hub bearings, cardan shaft intermediate support, clutch release bearing, water pump bearings, gearbox input shaft front bearing, ignition distributor drive shaft are lubricated with Litol-24, PS 1-13.

The bearings of the generator, starter, wiper and heater motors use Litol-24, N 158.

The wiper drive hinges, door hinges are lubricated with Litol-24, grease S.

Graphite grease USSA is used for springs.

The battery terminals are lubricated with Litol-24, grease C, VTV-1, gun grease.

For the flexible shaft of the speedometer, CIATIM-201, engine oil is used.

The cables of the parking brake, the hood lock are lubricated with Litol-24, TsIATIM-201.

Friction units and lubricants used in them are presented in Table. 24.