Gear Transmission Lubricant Knowledge Introduction

Gear transmission lubricating oil is referred to as gear oil, which is mainly used to lubricate various mechanical gear transmission devices.
Gear oil, like internal combustion engine lubricating oil, is also composed of mineral oil (or synthetic) base oil and corresponding additives.
become.Gear oils can be divided into two categories: vehicle gear oils and industrial gear oils.

Introduction to Gear Oil
Vehicle gear oil is mainly used for transmissions, steering gears, front and rear drive axles of automobiles and construction machinery.
Gear boxes, universal joint needle bearings and other parts can also be used for tanks, ships and other corresponding loads and working conditions.
on the gear transmission components.Industrial gear oil is mainly used for open, semi-open, closed and
Worm gears.

XNUMX. Working conditions and functions of gear oil:
Gears in various mechanical transmission mechanisms can be divided into parallel gears according to the positional relationship between their axes.
Shaft drives, intersecting shaft drives, and staggered shaft drives.Each type of transmission is different according to the shape of the gears and teeth.
The transmission mode, such as spur gears, helical spur gears, and herringbone spur gears driven by parallel shafts;
There are straight bevel gears, helical bevel gears, and spiral bevel gears for intersecting shaft transmissions; hyperbola for staggered shaft transmissions
Gears, worm gears, screw drives.

1. Gear transmission characteristics and gear oil working conditions
(l) The gear transmission efficiency is high. Generally, the transmission efficiency of cylindrical gears can reach 98%.
The radius of the equivalent curve of the wheel is small, and the condition of the oil wedge is poor.
(2) The gear transmission teeth are in line contact with the teeth, so the contact area is small and the unit contact pressure is high.
Generally, the contact pressure per unit of automobile gear can reach 2000-3000MPa, while the hyperbolic gear is higher and can reach XNUMX-XNUMXMPa.
(3) The gear transmission not only has linear contact, but also sliding contact, especially the hyperbolic gear, between the gear teeth
It has a relatively high relative sliding speed, generally up to about 8m/o.Under high-speed and high-load conditions, this will cause
The oil film becomes thinner or even partially ruptured, resulting in increased friction and wear, and even galling and galling.
(4) The working temperature of gear oil is generally lower than that of internal combustion engine oil, which varies with the ambient temperature to a large extent.
However, the temperature of vehicle gear oil is generally not higher than 100'C.Hyundai sedans use hyperbolic gears because of their axles
The line offset is large, and when the vehicle speed is high, the relative sliding speed of the gear wheel surface will be very high, so that the oil temperature reaches
160'C to 180'C.

2. The role of gear oil in gear transmission
(1) Reduce the wear of gears and other moving parts and prolong the life of gears.
(2) Reduce friction and reduce power loss.
(3) Disperse heat and play a certain cooling role.
(4) Prevent corrosion and rust.
(5) Reduce working noise, reduce vibration and impact between gears.
(6) Flush the dirt, especially the dirt between the tooth surfaces to reduce wear.

Second, the properties of gear oil:
Due to the different purposes of gear oil, the conditions of use are also very different, and its performance is as follows
1. Good oiliness and extreme pressure and anti-wear properties
Oiliness means that the gear oil can effectively adsorb the lubricating oil film between the moving lubricating surfaces, and has the
Properties of low friction effect.Wear resistance refers to the oil film that oil maintains between moving parts, which can effectively prevent metal
The ability of direct contact between the gear oil can be improved by adding some active substances with polar molecules to the gear oil.
The polar ends of these oily agents and the oxides on the metal surface will adsorb to form a firm oily
Film, the polar end of the oily agent may also form a metal soap-type lubricating film with the oxide on the metal surface, strengthening the tooth
The lubricating effect of the wheel oil prevents direct contact between the tooth surfaces and reduces friction, thereby reducing wear.some gears
It often works under severe extreme pressure lubrication conditions, and its pressure, sliding speed and local temperature are all
Very high, which requires the addition of extreme pressure additives to the gear oil.Extreme pressure additives are generally chemically active
Phosphorus-type or sulfur-phosphorus-zinc-type oil-soluble compounds, these additives under high temperature extreme pressure conditions and tooth surface metal
Iron-forming chlorine, sulfur, phosphorus compounds or complexes, forming a high melting point inorganic film, this extreme pressure film has
The performance of extreme pressure resistance, but also the effect of shock load resistance, can effectively prevent damage under high load conditions.
Tooth surface abrasion and bite.

2. Good viscosity-temperature characteristics
The viscosity of various lubricating oils decreases with the increase of temperature. The smaller the proportion of decrease, the better the viscosity-temperature performance.
the better.In particular, the working temperature of automobile and construction machinery gear oil varies widely. Therefore, it is hoped that gear oil
The less the change in viscosity with temperature, the better.If the viscosity-temperature characteristics of the gear oil are not good, the viscosity at startup is too large,
It is not easy to start, and the viscosity is too small when the operation reaches the high temperature limit.The viscosity of the gear oil is also important for usability
One of the properties is that the viscosity has a great influence on the formation of the oil film.In general, high viscosity gear oils are effective in preventing gear
and bearing damage, which can reduce mechanical noise and oil leakage; low-viscosity oil can improve the efficiency of mechanical operation.
There are advantages in terms of strong cooling and cleaning action and oil transfer.In order to reduce fuel consumption, foreign countries have implemented
Low viscosity of motor oil and gear oil.The advantage of low viscosity gear oil is that the stirring resistance of the gear teeth is small, and
It has good low temperature fluidity and can ensure lubrication under low temperature conditions.In recent years, some low-viscosity
In order to improve its lubricating performance, some multi-effect additives are added to reduce the power loss.
is very beneficial.Of course, when the body is used, the sealing of the gear case body should be strengthened to prevent gear oil

3. Good low temperature fluidity
Vehicle gear oils are required to maintain the necessary fluidity even at low temperatures.
If there is wax precipitation under the parts, and the viscosity rises sharply, effective lubrication cannot be ensured, and the low-temperature starting torque increases, making the
Increased fuel consumption.
Experiments show that the apparent viscosity of gear oil at low temperature has an important influence on the lubrication reliability when the vehicle starts.
ring.After the vehicle starts, the rear axle (front axle) gear oil is splashed to the upper part of the axle housing and then flows into the front axle of the drive bevel gear
Bearing, if this time is too long, the bearing may be burnt due to lack of oil.Therefore, it is required that the vehicle gear oil be used
When used, the apparent viscosity at low temperature is not more than 1.5X100000mPa.s.Appearance marked in vehicle gear oil specification
The temperature when the viscosity is 1.5X100000mpa.s, it determines the minimum temperature suitable for gear oil, it is selected
One of the important basis for using gear oil.In order to make the gear oil meet the requirements of use under low temperature conditions in winter, the gear oil
Pour point depressants are added to the oil to improve its low temperature fluidity.

4. Good thermal oxidation stability
Under harsh working conditions, under the catalysis of air, moisture and metal, the oxidation speed of gear oil
Accelerates, increases viscosity, produces insoluble and corrosive substances, as well as gums, asphaltenes, deteriorates properties and is easy to emulsify
It will melt and generate foam, which shortens the oil change interval.In order to delay the oxidation of gear oil, phenolic type,
Amine-type or sulfur-type antioxidant additives.

5. Good anti-rust and anti-corrosion
Rust resistance means that the gear oil protects the gear from rust, thereby ensuring the performance and extended service of the gear.
Use life.During the operation of the gear, the moisture in the air condenses into water in the gear box, so the gear is required to be
The oil should have good rust resistance.In order to improve the rust resistance of gear oil, sulfonate or fatty acid salt is generally added.
and other anti-rust additives.Gear oils with extreme pressure additives, because the extreme pressure additives contain sulfides, sulfur is not suitable for copper
Corrosion is easy to occur. Therefore, anti-corrosion additives should be added to the gear oil, which can form a protective effect on the metal surface.
Protective film to prevent corrosive substances from attacking the metal.

6. Good anti-foaming property
Gear oils are required to have good anti-foaming properties to ensure that under

The foam produced during mixing is less and disappears easily.