unified classification system gear oils in terms of performance, quality and purpose. The system is universally recognized throughout the world. API classifications (American Petroleum Institute), oils for mechanical transmissions. According to this system, oils are marked with a class sign API GL. Available five classes from API GL-1 before API GL-5 and several projects. In Europe it applies classification ZF TE-ML (Zahnradfabrik Friedrichafen), which covers all oils, including fluids for hydromechanical transmissions.
By API system GL oils are divided into quality classes. The main features of the classification are the design and operating conditions of the transmission, additional features- content of antiwear and extreme pressure additives.
The classification is described in the API document "Designation of operational lubricating oils for manual gearboxes and for axles. API Publication 1560, February 1976" ( API Publication 1560, Lubricant Service Designation for Automotive Manual Transmissions and Axles, February 1976).
API quality classes:
API GL-1
Oils for gears operating in light conditions.
Consist of base oils without additives. Small amounts of antioxidants, corrosion inhibitors, light depressant and antifoam additives are sometimes added.
Designed for spiral bevel, worm gears and mechanical boxes gears (without synchronizers) trucks and agricultural machines.
API GL-2
Contains anti-wear additives.
Designed for worm gears of vehicles.
Typically used to lubricate the transmission of tractors and agricultural machines.
API GL-3
Oils for gears operating under moderate conditions.
Contains up to 2.7% anti-wear additives.
Designed for lubrication of conical and other gears of trucks.
Not intended for hypoid gears.
API GL-4
Oils for gears operating in conditions of varying severity - from light to heavy.
Contains 4.0% effective extreme pressure additives.
Designed for bevel and hypoid gears with small axle displacement, for gearboxes of trucks, for drive axle units.
API GL-4 oils are designed for non-synchronized transmissions in North American trucks, tractors and buses ( commercial vehicles), for main and other gears of all vehicles. Currently, these oils are also the main oils for synchronized gears, especially in Europe. In this case, the label or data sheet of the oil must contain inscriptions about this purpose and confirmation of compliance with the requirements of the machine manufacturers.
API GL-5
Oils for the busiest gears operating in harsh conditions.
Contains up to 6.5% effective extreme pressure and other multifunctional additives.
The main purpose is for hypoid gears with a significant axle offset.
Used as universal oils for all other units mechanical transmission(except gearbox).
For a synchronized manual transmission, only oils that have a special confirmation of compliance with the requirements of machine manufacturers are used.
Can be used for limited slip differential if they meet the requirements of MIL-L-2105D (in the USA) or ZF TE-ML-05 (in Europe) specifications. Then the class designation has additional characters, for example, API GL-5+ or API GL-5 SL.
For manual transmissions(except hypoid), oils are mainly used API GL-3 And API GL-4;
for hypoid final drive:
API GL-4 - for medium loaded gears And
API GL-5 - for heavily loaded gears, including hypoid ones with a significant displacement of the axes. Oil companies produce universal oils designed both for gearboxes with synchronizers and for heavily loaded hypoid gears.
In 1995 API introduced new category MT-1, tightening the requirements for thermal stability and high-temperature deposits.
API MT-1
Oils for highly loaded units.
Designed for non-synchronized manual transmissions of powerful commercial vehicles (tractors and buses).
Equivalent API oils GL-5, but have increased thermal stability.
In 1998, API, working in conjunction with SAE and ASTM, introduced two new grades for gear oils: PG-1 And PG-2 (PG-1 - for manual transmissions of heavy trucks and buses; PG-2 - for driving axles of trucks and buses). In both categories of oils Special attention was given to high temperature properties. Category PG-2 sometimes referred to in the technical literature as a group GL-7.
API PG-2 (draft)
Oils for transmissions of driving axles of powerful commercial vehicles (tractors and buses) and mobile equipment.
Equivalent to API GL-5 oils but with improved thermal stability and improved elastomer compatibility.
In addition to the API classification, the US Army specification MIL-L-2105 A, B, C and D and the specifications of individual manufacturers of vehicles and units are often used: Chrysler; Ford; General Motors; Mac; MAN; Mercedes-Benz; Volvo; ZF; Rockwell etc.
US MILITARY SPECIFICATIONS
MIL-L-2105 A - specifications on lubricants for car gearboxes; roughly correspond to API GL-4.
MIL-L-2105 B- the currently most used specifications for gear oils for hypoid gears; can be compared with API GL-5.
MIL-L-2105 C- technical conditions valid since 1976 for multigrade gear oils of viscosity grades 75W, 80W/90 and 85W/140. They exceed specification MIL-L-2105 B and correspond API GL-5.
In addition to the specifications of the US Army, there are specifications of individual companies - manufacturers of cars and units: Chrysler; Ford; General Motors; Mac; MAN; Mercedes-Benz; Volvo; ZF; Rockwell etc. These specifications are indicated on the cans and canisters in which the oil is packaged.
Gear oils are used in most manual transmissions, transfer boxes, intermediate and driving axles, worm and rack and pinion steering gears of the car. In some cases, gear oils are used along with to ensure high resource operation of friction units: steering rod joints, cardan gears, ball bearings. At the same time, increased requirements are imposed on the tightness of these nodes.
Variety of requirements for gear oils, various conditions their use and the abundance of grades lead to the need to generalize the specifications of manufacturers and consumers of oils and create a unified classification system for their designation.
Currently, there are several classifications of gear oils abroad. The most famous of them are SAE and API. In Russia, GOST-17479.2-85 has been adopted for the division into viscosity classes and operational groups, as well as the establishment of standard designations. According to this standard, gear oils, depending on the viscosity at a temperature of +100 ° C, are divided into four classes: 9, 12, 18, 34, and according to the level of performance properties and possible areas of application - into five groups: 1, 2, 3, 4 , 6, 5.
Since according to the GOST designation it is quite difficult to determine temperature Range application of gear oils, domestic producers additionally indicate them according to SAE. SAE classification J306 divides gear oils by viscosity into "winter" (70W, 75W, 80W, 85W) and "summer" (80, 85, 90, 140, 250). All-season oils have a double designation, for example, 75W-90, 80W-140, etc.
The API classification subdivides gear oils according to their performance properties into seven groups: GL-1, GL-2, GL-3, GL-4, GL-5, GL-6 and MT-1. The most commonly used oils in passenger car transmission units are GL-4 (for spur, helical-bevel and hypoid gears under moderate operating conditions) and GL-5 (for hypoid gears under severe operating conditions).
Table. Selection of gear oils
| Category by API | Type | Application | GOST compliance |
|---|---|---|---|
| GL-1 | Mineral oil without additives | TM1 | |
| GL-2 | Contains fatty foods | worm gears, industrial equipment | TM2 |
| GL-3 | Contains extreme pressure additives | TM3 | |
| GL-4 | Manual gearboxes, spiral bevel gears (gearboxes and rear axles trucks) | TM4 | |
| GL-5 | Contains extreme pressure, antiwear and other additives | Hypoid and other types of gears (drive axles of passenger cars) | TM5 |
When choosing oil for transmission units, they are usually guided by two criteria: the specific loads acting in the mechanism and the relative slip speeds.
Depending on this, gear oils are selected that differ in viscosity and the amount of additives, primarily extreme pressure. The latter, as a rule, contain sulfur compounds, which cause chemical changes (modification) of the metal in critical conditions. The surface layer of the material does not break out, forming scuff marks, but turns into a thin film, which subsequently becomes a wear product. Despite the fact that the metal is chemically "corroded" in this case, the overall wear in difficult conditions there is less work.
In each specific case, the choice of one or another type of transmission oil should be determined, first of all, by the instructions of the car's factory operating instructions. The use of a liquid of a lower category according to API gradation is unacceptable, since it leads to the failure of the unit, and a higher one is impractical, primarily for economic reasons. If there are no special instructions, then the principle of choice is as follows.
The operation of truck units with spiral bevel gears is reliably ensured by oils with a level of performance properties GL-3. With regard to gearboxes with hypoid gearing, only oil of class GL-5 is suitable for them in all cases. This applies equally to trucks and cars. An oil of a lower group will not be able to protect the teeth of the hypoid pair from scuffing.
The need for passenger cars general case is as follows: GL-5 class oil is used for drive axles, GL-4 class oil is used for manual transmissions.
However, the choice of gear oil is determined not only by the level of its performance properties, but also by the viscosity of the lubricant. In the zone of moderate temperatures, it is better to focus on a viscosity value of 90. If it is more rational to use "all-weather" oil, then we can talk about varieties with indices 75W-90, 80W-90 and 85W-90. Moreover, the latter is not very suitable for harsh winters, 80W-90 class oil is quite versatile, and 75W-90 allows you not to experience difficulties even during the most severe frosts.
Buy only quality branded products. Gear oils such famous companies like Mobil, Esso, Molykote help prevent wear and tear on power transmission systems and components, and maximize oil change intervals.
The classification of gear oils is complex and extensive. But for ordinary motorists there is no need to understand numerous standards. It is enough to have an idea of the most common. Gear oils, like motor oils, are classified by viscosity and their performance properties.. They are used in gearboxes, steering, drive axles and gearboxes, transfer cases.
Viscosity classification
Initially American, now the SAE classification system has become international. This classification of gear oils provides for 9 varieties: 4 winter and 5 summer. Winter varieties are indicated by the letter W. All-season varieties are distinguished by double marking: 1 value corresponds to winter varieties, 2 to summer varieties. For example, SAE 75W-90. Winter varieties are designated:
- 70W - for use at temperatures down to minus 55°С;
- 75W - for use at temperatures down to minus 40°С;
- 80W - for use at temperatures down to minus 26°С;
- 85W - for use at temperatures down to minus 12°C.
Summer varieties have digital SAE designations 80, SAE 85, SAE 90, SAE 140 and SAE 250. SAE 90 is used in transmissions budget cars with relatively small motors. SAE 140 is designed for SUVs and large machines With powerful engines. SAE 250 is used in transmissions of sports and racing cars.
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Classification by properties
According to their performance properties, lubricating fluids are divided into 6 classes according to API and GOST standards. The API GL-1 standard (corresponding to GOST TM-1) is designed for gearboxes operating under low loads, as well as for lightly loaded spur, worm and bevel gears. The API GL-2 (GOST TM-2) standard differs from the previous one in the presence of antifriction components in oils. Category API GL-3 (GOST TM-3) is intended for step boxes gears, steering mechanisms, main and hypoid gears operating in not very severe conditions. An obsolete standard for automobiles and other trackless vehicles. Unlike GL-2, it has better anti-wear properties. API GL-4 (GOST TM-4) is currently the most widely used in transmissions, transmissions and steering mechanisms of modern vehicles under moderate operating conditions. Gear lubricants of this group are characterized by high content various additives, including high performance extreme pressure additives.
The API GL-5 class (GOST TM-5) is the second most common lubricating fluid used in gearboxes and gearboxes operating in moderate to severe operating conditions. Products belonging to this group are invariably used in manual boxes gears and cardan drives of motorcycles, whose operating conditions are characterized by shock and alternating loads. They are distinguished by a high content of sulfur-phosphorus-containing extreme pressure additives. Liquids API categories GL-6 (GOST TM-6) are used in mechanisms operating under conditions high speeds, enormous torques and shock loads. Actually this group is not used, and if necessary, the GL-5 group with increased operational properties. In 1998, the PG-2 category was developed, paying high attention to the high temperature properties of oils, often referred to in the technical literature as API GL-7.
Except API standard many other specifications exist: US Army standard, regulations individual car manufacturers, classification of working fluids for automatic boxes gears.
There is no single classification of oils for automatic transmissions. Each manufacturer develops its own classification. For example, at General Motors, gear oils have letter designation Dextron and a number from I to IV. Dextron IV is used in the most modern cars with automatic boxes. Concern Ford labels its oils as Mercon. Honda company– ATF. Separate standards for automatic transmission fluids are explained by the fact that inside automatic transmissions, oil performs not only a lubricating function, but also the function of transmitting mechanical energy.
Therefore, higher requirements are imposed on this group of oils compared to lubricating fluids for mechanical transmissions.
Gearbox manufacturer ZF designates its oils as ZF TE-ML with a number from 1 to 14. Category TE-ML 1 is used for non-synchronized manual transmissions. Category TE-ML 2 - for mechanical and automatic transmissions trucks and buses. The number 3 indicates oils for torque converters of mobile mechanisms. Number 4 - oils for ship transmissions. TE-ML 5 group is used in driving axles off-road equipment. TE-ML 6 - for transmissions and hydraulic drives of tractors. TE-ML 7 - for hydrostatic, mechanical and electric drives, drives of lifting and rotary mechanisms. Liquids of the TE-ML 8 group are used in steering mechanisms that do not have hydraulic boosters. Liquids of the TE-ML 9 group - in steering mechanisms with hydraulic boosters. 10th, 11th and 14th groups - for automatic transmissions of cars. 12th - for driving axles of cars, trucks and buses. TE-ML 13 - for special units military equipment.
As well as motor oils, transmission oils are mineral, synthetic and semi-synthetic.
Transmission lubricants are used in gearboxes, transfer cases, axles and steering mechanisms. There are quite a few cars where they pour the same engine oil. But in some mechanisms that are subjected to particularly heavy and complex loads, and where it is difficult for oil drops and mist to get from it, a supply of transmission oil under pressure is required.
Separate different groups and types motor fluid. The classification of gear oil is also different.
Accepted classifications
One of the international classifications is the division by viscosity. This classification of gear oils is called SAE. In it, lubricants are divided into seven classes, four of which are winter (indicated by the letter W), and the remaining three are summer. All-season marking implies a double designation, for example, 80W90, 75W140 and others.
Another classification of gear oil, called the API, involves a division into six groups. They are used depending on the goals, which is why their own type is provided. gear train, specific loads and temperature.
General classification of gear oils according to SAE
This classification was developed by the American Society of Engineers. She became widely known. Many motorists know her better than any other.
The viscosity grade of the lubricant can be found in the owner's manual for each vehicle.
The choice of what this classification of gear oils offers is made on the basis of temperature indicators environment where the vehicle will be used. Viscosity properties are determined in relation to the achievement of 150 thousand cP according to Brookfield. If this value is exceeded, the gear shaft bearings will begin the process of destruction. To prevent this from happening, you should strictly follow the recommendations for low temperature data, choosing the right lubricant.
If the car is planned to be operated at a temperature of the order of minus thirty degrees and below, then hydrocracking or synthetic lubricants, as well as semi-synthetic viscosity 75W-XX with a viscosity limit of 5000 cP.
High temperature is determined at 100 degrees. Upon reaching it, the parts should not begin to collapse, even if you have to be under such influence for 20 hours or more.
Classification of gear oils by viscosity: details
Here, just as in motor vehicles, lubricating fluids are divided according to seasonality:
- winter - 70W, 75W, 80W, 85W;
- summer - 80, 85, 90, 140, 250.
In this classification, such a division is conditional, since different manufacturers have their own design features.
But the SAE J306 standard, for example, has requirements that must be met transmission fluids. So, they should contain a single degree of winter or summer series, or a combination of both. There cannot be two winter degrees at once.
In addition, if motor lubricants are indicated in the range from 0 to 60, then transmission range from 70 to 250.
So the developers tried to prevent possible errors when choosing oil. Thus, if motor and transmission fluids have the same viscosity, then according to SAE their values \u200b\u200bwill be different.
API in general
A universal classification of gear oils for all types, alas, has not yet been created. But on API class it is most convenient to classify lubricants.
According to her cars oils of the GL-4 or GL-5 group are used. GL-4 is suitable for mechanics and gearboxes with hypoid or helical-bevel pairs and is used in moderate climatic conditions. And GL-5, in addition to moderate, can also be used in harsh conditions on different types gears.
Separate API groups
Let's take a closer look at all the groups that the API gear oil classification represents.
The GL-1 group includes mineral lubricants. There are no additives in these oils, except for those that have antioxidant and antifoam properties.
GL-2 includes oils with which are used for worm gears with low rotating speed.
GL-3s are lubricants that already have a considerable amount of additives to which they belong, and have wear-resistant properties. They are used in gearboxes with several steps and for steering, in main and hypoid gears. Helical-bevel gear pairs work with oil, designed for operation at low speeds and not in harsh conditions.
The GL-4 group has a high percentage of additives. These include those that have anti-seize properties. They are mainly used in cars with conventional gearboxes. The lubricant is able to function properly in such gearboxes where there are high speed rotations and low torques, or vice versa.
GL-5 includes lubricants capable of operating in difficult conditions where it is necessary to exert a lot of effort and overcome strong loads. These oils are used for different models cars and motorcycles. Applicable for hypoid gears, pairs of gears working with impacts. Lubricants contain a large number of additives based on phosphorus sulphide elements and reduce the likelihood of metal scuffing.
GL-6 oils provide Good work even under harsh operating conditions. They effectively withstand rotational speed, high torques and shock loads. They are inherent in the presence of a large number extreme pressure additives compared to other groups. But the oils of this group are not often used.
The main number of gear oils is made on mineral basis. Synthetics are used very rarely.
Other classifications
The CAE and API classification of gear oil is the most common. But there are other divisions as well. For example, lubricants for automatic gearboxes belong to a separate category. They are not covered by the API as a gear oil classification. Zik, Total, Mobil and other manufacturers are guided by their own indicators in the manufacture of lubricating fluids.
ATF classification
Automatic machine oils are often dyed in bright color so that the motorist does not confuse and fill it in the manual transmission. It is also not allowed to mix multi-colored liquids,
There is no classification for automatic transmission, which would be as unified as for manual transmission. Therefore, manufacturers themselves deal with this issue. So, they use the Dexron classification, and Ford - Mercon.
ZF classification
The classification of the company Zahnradfabrik Friedrichshafen, shortly ZF, is gaining wide popularity. It is the leader among European manufacturers gearboxes and motor installations. Having developed its own classification, the company offers to focus on their classes in terms of quality and viscosity.
Each gearbox has its own oils. The division provides for both an alphabetic code and a numeric one.
What to base your choice on
The classification of gear oils according to API, SAE, and so on greatly facilitates the choice. But by acquiring lubricating fluid, you should also understand what tasks it should solve. Among them stand out:
- preventing too much friction and increased wear on gear surfaces or other transmission components;
- the energy expended due to the creation of the film must be reduced;
- creation of heat removal;
- stopping or minimizing the oxidation process;
- no negative effect on the reaction of transmission parts on the surface;
- non-reaction with water;
- preservation of original properties during long-term storage;
- reduction of noise and vibration that occurs during transmission work;
- non-release of toxic fumes when heated.
Properly selected gear oil will successfully solve its problems and help extend the life of the mechanisms.
