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УДК.665.76
REQUIREMENTS, WORK CONDITIONS AND TRANSMISSION OIL FUNCTIONS
Abdullayev Alimardon Ikromjonovich
ANDIJAN STATE TECHNICAL INSTITUTE
Annotation:
Gear units in vehicle units (extensions, lubricating oils, lubricants, distribution
boxes, differentials, cylindrical, conical, cherubes, hypoids and other extrusions in the steering
wheel). Their main task is to remove the worktable surfaces and to rub friction bearing units
reducing the amount of wasted money. Also, these oils the heat generated from the frictional
parts must be removed, corrosion-resistant, and the car must be maintained for a long time.
Key words:
transmissions, cardan extensions, differential, gear wheels, extensions, extension
boxes, gippoid extension.
Transmission oils are used in gearboxes, bridges, distribution boxes, steering mechanisms, and
others. The share of transmission oils in the total volume of vehicle lubricants during the entire
operation period is 0.3...0.5%.
The pressure in the contact zones of cylindrical, conical, and worm gears can reach 2000 MPa,
the sliding velocity of the teeth relative to each other at the engagement inlet in conical and
cylindrical gears varies within the range of 1.5...12 m/s, in worm gears - 20-25 m/s, the operating
temperature of the oil in transmission units varies from ambient temperature to +200°C, and at
the points of contact of the teeth - up to +300°C and higher.
Various operating requirements are imposed on transmission oils, sometimes quite contradictory.
Oils must, on the one hand, maintain high viscosity at operating temperatures so that the film
does not break and the gaps are normally sealed, and on the other hand, do not become too
viscous at low ambient temperatures so that at the beginning of the unit's operation, the cold oil
does not interfere with the free rotation of the gears [1].
Oils operating in automatic transmission boxes are subject to much higher requirements for their
viscosity, anti-friction, anti-wear, and anti-oxidation properties compared to those used in other
units. Since automatic boxes include several completely different units: a hydraulic transformer,
a gearbox, and a complex control system, the range of oil functions is quite wide. The average
operating temperature of the oil in the automatic box crankcase is 80-95°C, while in hot weather,
during the city cycle, it can rise to 150°C. The automatic box's design is such that if more power
is removed from the engine than is required to overcome the road resistance, its excess is used
for internal oil friction, which further heats up [2].
High speeds of oil flow movement in the hydrotransformer and temperature cause intensive
aeration, leading to foaming, which creates favorable conditions, firstly, for the oxidation of the
oil itself, and secondly, for metal corrosion. The diversity of materials in the friction pairs of the
automatic box (steel-metal-ceramics, steel-bronze) makes it difficult to select anti-friction
additives for oils. Moreover, heterogeneous parts, working in foamed and gradually saturated
with oxygen and water oil, form electrochemical vapors that activate corrosive wear. Under such
conditions, it must not only maintain its operational properties and protect the friction surfaces
but also, as a medium transmitting torque, ensure the transmission's high efficiency. And here,
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the requirements for viscosity are directly opposite to those imposed when it comes only to
lubrication.
High viscosity is required to lubricate the gears. For normal operation of the hydrotransformer -
low (4-9 ct. at 100°C) [3].
In addition, oils must have high anti-corrosion, antioxidant, anti-foaming, and other properties,
as well as high thermo-oxidative and mechanical stability.
Mechanical stability of motor oils is an indicator characterizing the degree of change in the
viscosity of thickened motor oils (containing viscous additives) during engine operation. As a
result of the mechanical destruction of viscous additives during operation, the oil's viscosity at
99 °C decreases by 2-3 cm (mm2/s) or more, i.e., by 15-25% compared to the viscosity of fresh
oil.
The mechanical stability of oils is assessed after 10 hours of oil testing according to the L-38
method. A sample of used oil (25 g) is taken from the unit and heated to 120±5°C in a vacuum
(statin, pressure 100 mm Hg), in a nitrogen current, in a special flask with a volume of 50 ml.
After this, the oil is held for 1 hour. Then, the oil is passed through a filter with a pore diameter
of 0.1 μm and its viscosity is determined at 99°C. The oil is considered to have passed the test if
its viscosity does not exceed the limits specified in the specifications. [5]
Based on the above, various and sometimes contradictory requirements are imposed on
transmission oils. Thus, oils, on the one hand, must have high viscosity at operating temperatures
to preserve the lubricating film and normally seal the gaps, and on the other hand, they must not
be too viscous at low temperatures so that the cold oil does not interfere with the free rotation of
the gears when the unit is started. In addition, transmission oils must be characterized by high
thermo-oxidative, mechanical stability, and anti-corrosion properties. The resistance of oil to
mechanical stress is determined by the rejection of using high concentrations of polymer
viscosity additives. They increase the viscosity-temperature properties of the oil, but under the
influence of mechanical influences, they break down, as a result of which the oil's viscosity can
sharply decrease.
Literature:
1. R Baltenas, A.S. Safonov and others. Transmission oils. Plastic lubricants. 2001 206 s.
S.Peterburg.
2. Fuels, lubricants, technical fluids. Range and application. Directory. / IG Anisimov and others
- M .: 1999 Techinform.
3. Safonov A.S., Ushakov A.I., Yuskovets N.D. Automotive maintenance materials. SPb .:
Gidrometeoizdat, 2000.-223
4. Seleznev, M. V. Change in acid number of transmission oils in transmission units of
automobiles KAMAZ 2014
5. Glushchenko, A. A. Hydrocyclone for the purification of used oils / A. A. Glushchenko, V. M.
Kholmanov, M. V. Seleznev // Mechanization and Electrification of Agriculture. 2014
