Lubricants and technical fluids are used for mechanisms and machines to perform work functions. They provide reliability and operational efficiency of various equipment.
Types of Lubricants
In the processes of the mechanisms, the contacting surfaces move and wear with heat due to friction. To reduce it, mineral and synthetic lubricants are used.
Lubricants and technical fluids mainly contain products as a basis:
- distillate - vacuum distillation of fuel oil (light fractions);
- residual - obtained by distillation of the tar.
A particular type of mineral oil is obtained by mixing distillate and residual components in certain proportions and adding additives to them.
Synthetic oils are produced by the synthesis of certain hydrocarbons with the addition of additives that improve operating conditions.
Types of Lubricants
- motor;
- transmission;
- hydraulic;
- greases.
Additives to lubricants
The requirements for oils operating in different conditions are constantly being tightened. The basic base is not able to fully provide the necessary properties that can only be created by adding additives to oils and process fluids. Their number ranges from fractions of a percent to 15% and higher.
Types of additives:
- single - function - provide one of the properties: anti-wear, anti-seize, viscous, antioxidant, anti-friction, anti-foam, depressant, detergent-dispersant, etc .;
- multifunctional - high-performance polymer compounds that give the oil several operational characteristics;
- additive packages and compositions - mixed and chemically related additives that improve properties and create a new quality (up to 15 components).
Properties of oils and technical fluids
For products such as grease and working fluid, technical specifications or GOST provide a set of different characteristics that determine the conditions for their use.
- Lubricity is a combination of anti-friction, anti-wear and anti-seize properties. The main indicator is the viscosity, which characterizes the resistance to flow between the fluid layers (dynamic viscosity, Pa ∙ s). Another characteristic is the kinematic viscosity, which is determined by the rate of fluid flow under its own weight through the capillary of a viscometer. It is measured in m 2 / s. For oils, the dependence of viscosity changes on temperature is especially important. It is evaluated through a viscosity index.
- Thermo-oxidative stability is an indicator of the antioxidant properties of oil, characterized by the time it takes for a thin oil layer to turn into a varnish film. The higher it is, the better the product. The oxidation process begins when heated to 50-60 ° C. The intensity increases significantly, starting from 250 ° C. In this case, the oil darkens and its physicochemical properties change.
- The washing and dispersing properties of engine oil reflect its ability to reduce the formation of sediments and carbon deposits inside the engine and to maintain contamination products in suspension.
- The anticorrosion properties of oils gradually deteriorate as wear products accumulate. Corrosion activity is estimated by the acid number determined by the amount of mg KOH necessary to neutralize acids in 1 g of oil. The acid content during its operation increases by 3-5 times and they are most dangerous for parts. The properties of oils are improved by the introduction of additives that form protective films on the surface of the metal or neutralizing acids with alkaline earth metals.
Motor oils
Reciprocating internal combustion engines (ICE) are particularly in need of lubrication. They use motor oils, the properties of which are selected specifically for each equipment.
For a long time, pure mineral oil was used for ICE. Modern forced engines required the introduction of additives. All-season oils are predominantly used, satisfying viscosity requirements over a wide temperature range.
For many units, semi-synthetics are suitable - mineral water with the addition of synthetic organic components. When buying it, you need to pay attention to the authenticity and quality of the product. Most adhere to the recommendations of the instructions for this vehicle. Here you need to know that manufacturers recommend the brands of oils with which they make a profit. Those who are not very versed in product brands should follow their advice.
Motor Oil Classification
According to their operational properties, motor oils are classified into groups for engines:
- A - non-accelerated carburetor (few additives).
- B - slightly accelerated (3-5% additives).
- B - medium-boosted (up to 8% of additives).
- G - highly accelerated (8-12% of multifunctional additives).
- D - highly accelerated heavily loaded diesels (18-25% of additives).
According to the degree of viscosity, motor oils are 7 classes: 6, 8, 10, 12, 14, 16, 20. All-weather are produced from mineral motor oils by thickening the base with low viscosity macropolymer additives. There are 10 classes, each of which is represented as a fraction, for example, 4z / 8. The numerator indicates the viscosity class at -18 ° C, and in the denominator - at 100 ° C.
If a brand of motor oil is known , for example, M-6 s / 10B 2 , it can be deciphered as follows: M - motor, 6 s - viscosity class with a thickening additive, 10 - viscosity at 100 0 C, B - medium-boosted engine, 2 - for diesel engines .
Checking the quality of engine oil is carried out in the diagnostic center, which requires certain costs. There is a simple way to check: with a dipstick, put a drop of oil on the surface of the newspaper. If it quickly fades, leaving several thick circles on the surface, this indicates a quality product.
High drop stability characterizes the loss of beneficial properties. Such control is suitable for assessing the quality of fresh lubricant.
Gear oils
The transmission includes gearboxes and distributions, axles, steering gear, etc. Lubrication is necessary for different types of gears. Transmission oils are made from a mineral or semi-synthetic base with functional additives based on chlorine, phosphorus, sulfur and disulfide, creating a protective film that protects parts from negative influences. The viscosity of the product should preserve the film at high load and temperature. In the cold season, the viscosity of the oil should not interfere with the operation of the mechanisms, for which a composition suitable for the viscosity index is selected.
Functions of gear oils:
- reduction of friction and wear losses;
- heat removal from contact zones;
- reduction of shock loads;
- non toxicity and non-waste.
The most affordable mineral fluids and lubricants. They have good characteristics, creating a reliable protective film.
Synthetic oils are much higher in quality, but they are the most expensive products. Semi-synthetic is good value for money.
Domestic gear oils are in viscosity grade 4. By operational properties they are divided into 5 groups. In the labeling of different compositions, the main characteristics are indicated, for example, -5-9 - gear oil of the 5th group, viscosity of the 9th class with a thickening additive. An example of a foreign classification is SAE 80W-90, where the marking indicates: 80 - viscosity class, W - winter, 90 - corresponds to a minimum viscosity of 14 mm 2 / s at 99 0 C.
Hydraulic fluids
In systems of hydromechanisms and drives, special technical fluids are used to bring them into action. Requirements are made to them:
- good pumpability and a small dependence of viscosity on temperature;
- high anti-corrosion properties and the absence of swelling or destruction of hydraulic seals;
- high lubricity;
- chemical and physical stability with preservation of initial properties for a long time during operation;
- lack of impurities, water and aggressive substances that cause corrosion.
Hydraulic oils include about 20 items. They are produced by mixing petroleum distillates with additives. The most commonly used AU spindle oil. Known oils are MG-30, M-2IHP, AMG-10, MGE-10A.
Fluids for shock absorbers and brake systems
Technical brake fluids are designed to operate in hydraulic systems of machines. Requirements are made to them:
- low freezing point;
- low viscosity;
- good lubricity;
- anticorrosion resistance;
- lack of destructive effect on rubber seals.
Types of brake fluids.
- ESC - 60% castor oil + 40% ethyl alcohol.
- BSK - 50% castor oil + 50% butyl alcohol.
- 35% glycerol + 65% alcohol.
- Neva and GTZh-22M - based on glycol with additives.
- "Tom" is a mixture of glycols with boric acid esters.
Castor-based brake fluids at a temperature below -20 0 C freeze, and only alcohol remains in the solution. In this regard, they are selected depending on the region. Replacement of technical fluids in winter and summer is rare. Most prefer to use an all-weather fluid, which is glycol-based formulations. The best of them is Tom, which has good anti-corrosion and anti-wear properties.
For shock absorbers, the compositions AZh-12T and MGP-10 are used, which are a mixture of mineral oil of low viscosity with an organosilicon liquid and additives.
Technical coolants
The liquid cooling system is designed to maintain the required temperature regime of the internal combustion engine. It is closed, taking heat from working mechanisms and passing it through the radiator to the environment.
Previously, the power plants were cooled by water, but it had to be abandoned due to insignificant freezing and boiling thresholds. In addition, it forms scale and is a source of metal corrosion.
Subsequently, technical coolants changed in composition, but water remained the basis.
The most widely used antifreeze is a mixture of water with glycols and special additives. They have the following advantages:
- low freezing point;
- slight expansion during freezing;
- boiling point above 110 ° C;
- good lubricating properties.
Low-cost ethylene glycol antifreezes are toxic industrial fluids. Compounds based on propylene glycol have less toxicity, but their cost is much higher.
Conclusion
Oils and technical fluids are on the market in a wide range. A motorist without experience of their use should be guided by the compositions recommended by the instructions for a particular make of car. Particular attention should be paid to the winter period of operation. When storing a car in a heated garage, all-weather fluids are quite suitable. It is important to focus on quality indicators, not prices. In addition, other factors should be considered, in particular the life of the engine.