Principles of selecting lubricating oil for reducers-Wanhui Machinery

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Principles of selecting lubricating oil for reducers

2025-04-29

The primary factor in selecting a reducer lubricant is viscosity. Viscosity is a very important physicochemical indicator of gear oil, and the meshing speed of the gears is the main indicator for viscosity selection.

Principles of selecting lubricating oil for reducers

The primary factor in selecting reducer lubricating oil is viscosity. Viscosity is a very important physicochemical indicator of gear oil, and the meshing speed of the gears is the main indicator for selecting viscosity. A suitable viscosity of reducer gear oil results in low internal friction of the lubricating oil, significantly reducing gear surface wear, transmission noise, and vibration.
The viscosity of reducer lubricating oil is mainly achieved through base oil and viscosity index improvers. The viscosity of lubricating oil base oil is related to its molecular structure and molecular weight: the larger the average molecular weight, the greater the viscosity of the oil. As for base oils, mineral oil-type lubricating oils include three types: lubricating oils refined from paraffinic crude oil, lubricating oils refined from naphthenic crude oil, and lubricating oils refined from intermediate-base crude oil. Lubricating oils refined from paraffinic crude oil have better viscosity-temperature performance than the other two. Good viscosity index improvers not only require high viscosity-increasing ability and good shear stability, but also good low-temperature performance and thermal oxidation stability. Viscosity index improvers with poor shear stability, due to the breakage of their polymer main chains under shear stress, resulting in reduced molecular weight and thinning of the oil, thus having a series of effects on wear and oil consumption. For lubricating oils of the same viscosity grade, if unrefined base oil and poor viscosity index improvers are used, although a certain viscosity standard can be achieved through blending, the viscosity-temperature performance and shear stability are poor, and the expected service life cannot be achieved. Therefore, for low-speed, heavy-load cement reducers, it is best to avoid using such lubricating oils and instead choose high-quality advanced lubricating oils, because their base oils and viscosity index improvers are both better.
The higher the viscosity of the gear oil, the stronger its ability to protect the gear surface from various types of damage, thus reducing reducer wear. However, if the viscosity is too high, it is difficult for abrasive particles to settle, reducing the lubricating oil's flushing and heat dissipation effects on the gear surface, resulting in poor lubrication. At the same time, abrasive particles suspended in the oil entering the meshing area can easily cause abrasive wear. In addition, excessive viscosity increases transmission resistance, increases gear surface temperature, and increases power consumption. Generally speaking, an increase in viscosity grade increases energy consumption by about 1% to 5%, and the stability and anti-emulsification performance of the oil will also decrease. However, high viscosity has obvious advantages in reducing noise and preventing oil leakage. In addition, for equipment with uneven loads, frequent starts, and operation in high-temperature environments, the viscosity should be slightly higher.
In summary, reducers should use high-grade lubricating oils with suitable viscosity. For large, low-speed, heavy-load reducers, extreme pressure type heavy-load gear oils with high viscosity should be used as much as possible, because they have better extreme pressure anti-wear properties, thermal oxidation stability, corrosion and rust prevention, and excellent anti-emulsification performance than medium-load gear oils. This facilitates the formation of a chemical film on the meshing surface of the gears, thereby protecting the gear surface and minimizing reducer wear. High-grade lubricating oils suitable for reducers include Tieba BIG7 Super Gear Lubricating Oil, Tieba SYNTHETIC GEAR OIL Extreme Pressure Synthetic Gear Lubricating Oil, and Tieba SYNMOLY Synthetic Gear Oil, all of which are very suitable for use in reducers.

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