Gear Oil

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AGMA is the international standard to gear & gear oil .gear oil is based on the specifications. But Gear oil, like engine oil, has a SAE quality level and API performance. It has a very low viscosity and is fully compatible with moving parts of automobiles and industries.

The main task of gear oil is to lubricate the gears of the manual gearbox and so on.

Gearbox oil in two forms MTF: Special for manual gearbox ,  (gear) ATF gearbox gear oil: special for automatic gearbox Gear oil is the same as vascazine.

Main specifications include :

1- Viscosity of gear oil :The viscosity of synthetic oils according to the ISO grading system is between 32 to 6800. Synthetic gear oils are used for gears operating under extreme conditions : very low or very high temperatures, high pressures.

2- High heat resistance of gear oil : Compared to conventional oil, it also offers greater resistance to oxidation and stable performance at high temperatures and under high loads.

3- Resistance to EP( extreme pressure) Dehydration property : Creating foam and bubbles -Stability against Rust and abrasions - International AGMA standard Anti-corrosion - control of sludge and sediments Anti-corrosion.

 

-R&O type : mineral base  and Rust & Oxidation inhibitor

-EP type :mineral base  and Extreme Pressure

-Compound type : mineral base  and 3% to 10% fatty oil or synthetic fatty

-Synthetic type : POA, ESTER ,synthtic based,warm gear

 
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Gear oil is a lubricant made specifically for transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. It is of a high viscosity and usually contains organosulfur compounds.

Some modern automatic transaxles (integrated transmission and differential) do not use a heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic transmission. Gear oils account for about 20% of the lubricant market.

Most lubricants for manual gearboxes and differentials contain extreme pressure (EP) additives and antiwear additives to cope with the sliding action of hypoid bevel gears. Typical additives include dithiocarbamate derivatives and sulfur-treated organic compounds ("sulfurized hydrocarbons").

Gear oil being added to the final reduction gears in a scooter.

EP additives which contain phosphorus/sulfur compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers; the GL-1 class of gear oils does not contain any EP additives and thus finds use in applications which contain parts made of yellow metals.

GL-5 is not necessarily backward-compatible in synchro-mesh transmissions which are designed for a GL-4 oil: GL-5 has a lower coefficient of friction due to the higher concentration of EP additives over GL-4, and thus synchros can not engage as effectively.

 

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Which oil is best for gearbox?

Some gearbox manufacturers specify a “pure” or “straight” mineral oil gear lubricant. This means it should not contain chemically active EP additives, although it may still contain various other highly desirable additives.

Are all gear oils the same?
All gear lubricants are definitely not the same. There are differences in the additive technology used for lubricants for each specification, and just because one type of gear oil works well for one type of gear application, that doesn't mean it will work well for all.

 

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Please pay attention to the viscosity table to better evaluate the different viscosity in different systems.

 

  Gear oil, you may be tempted to think they're the same thing, but they're not. Gear oil is specifically designed to protect, lubricate, and cool gearing systems. Engine oil lubricates the bearings and protects your car's engine from the additives in gasoline.

API ratings

Gearbox oils are classified by the American Petroleum Institute using GL ratings. The higher an oil's GL-rating, the more pressure can be sustained without any metal-to-metal contact taking place between transmission components.

Separate differentials usually have higher pressure between metal parts than gearboxes and therefore need higher GL-rating. For example, most modern gearboxes require a GL-4 oil, and separate differentials (where fitted) require a GL-5 oil.

While they take the same form, the viscosity grades for gear oils are on a different scale than the viscosity grades for an engine oil. The viscometrics for gear oils are standardized in SAE J306. Multigrade gear oils are becoming more common; while gear oil does not reach the temperatures of motor oil, it does warm up appreciably as the car is driven, due mostly to shear friction (with a small amount of heat conduction through the bellhousing from the engine block).

 

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Fully synthetic gear oils are also used in many vehicles, and have a greater resistance to shear breakdown than mineral oils.

API Category GL-1 (inactive) designates the type of service characteristic of manual transmissions operating under such mild conditions of low unit pressures and minimum sliding velocities, that untreated oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour depressants may be used to improve the characteristics of lubricants intended for this service. Friction modifiers and extreme pressure additives shall not be used.

API Category GL-2 (inactive) designates the type of service characteristic of automotive type worm-gear axles operating under such conditions of load, temperature and sliding velocities, that lubricants satisfactory for API GL-1 service will not suffice.

API Category GL-3 (inactive) designates the type of service characteristic of manual transmissions and spiral-bevel axles operating under mild to moderate to severe conditions of speed and load. These service conditions require a lubricant having load-carrying capacities greater than those that will satisfy APL GL-1 service, but below the requirements of lubricants satisfying the API GL-4 service.

with wide operation ranges and temperature differences in the vicinity of viscosity.

API Category GL-4 designates the type of service characteristic of spiral-bevel and hypoid gears in automotive axles operated under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications.

API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.

API Category GL-6 (inactive) designates the type of service characteristic of gears designed with a very high pinion offset. Such designs typically require (gear) score protection in excess of that provided by API GL-5 gear oils. The original API GL-6 test equipment is obsolete.

API Category MT-1 designates lubricants intended for non-synchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting API MT-1 provide protection against the combination of thermal degradation, component wear, and oil seal deterioration which is not provided by lubricants meeting only the requirements of API GL-4 and API GL-5.

 

MIL-PRF-2105E this specification released in 1995 combines the performance requirements of its predecessor (MIL-L-2105D) and API MT-1. MIL-PRF-2105E maintains all existing chemical/physical requirements, stationary axle test requirements, field test requirements and data review by the Lubricants Review Institute that were required under MIL-L-2105D. It also adds the stringent oil seal compatibility and thermal durability test requirements under API MT-1.

 

MIL-PRF-2105E has been re-written as SAE Standard J2360. SAE J2360 standard is a new global quality standard that defines a level of performance equivalent to that defined by MIL-PRF-2105E, a U.S. military standard for approval that was not available to oil blenders in all parts of the world.

 

It includes all of the most recent axle and transmission testing requirements identified in API GL-5, API MT-1, and MIL-PRF-2105E including the need to demonstrate proof-of-performance through rigorous field testing.

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