Issue 89: Hengyu Guoqiang reducer - lubricant viscosity selection
Time：2018-10-01 | Source：恒宇国强 | Browse：911959
The viscosity of reducer lubricating oil is mainly realized by base oil and viscosity index improver. The viscosity of lube base oil is related to molecular structure and molecular weight: the higher the average molecular weight is, the higher the viscosity is. As far as base oil is concerned, there are three kinds of mineral oil type lubricants, including those refined from paraffin base crude oil, naphthenic base crude oil and intermediate base crude oil. However, the viscosity temperature performance of lubricating oil refined from paraffin base crude oil is better than the other two. A good adhesive requires not only high viscosity and shear stability, but also good low temperature performance and thermal oxidation stability. The viscosity index agent with poor shear stability has a series of effects on wear and fuel consumption due to the main chain breaking and molecular weight decreasing under the action of shear stress. For lubricants of the same viscosity brand, if non refined base oil and poor viscosity index agent are selected, although a certain viscosity standard can be reached after blending, the viscosity temperature property, shear stability and other properties are poor, and the service life can not be reached. Therefore, for low-speed and heavy-duty cement reducer, try to avoid using this kind of lubricant, and choose high-quality high-grade lubricant, because its base oil and adhesive are better. The higher the viscosity of the gear oil, the stronger the protection ability to prevent the tooth surface from various damages, so the less the wear of the reducer.
But the viscosity is too high, the abrasive particles are not easy to precipitate, which reduces the flushing effect of lubricating oil on the tooth surface and endothermic cooling effect, resulting in poor lubrication. At the same time, the abrasive particles suspended in the oil enter into the meshing zone, which is easy to cause abrasive wear. In addition, excessive viscosity will increase the transmission resistance, tooth surface temperature and power consumption. Generally speaking, if the viscosity is increased by one grade, the energy consumption will increase by 1% ~ 5%, and the stability and demulsibility of the oil will decrease. However, high viscosity has obvious advantages in reducing noise and preventing oil leakage. In addition, the viscosity of equipment with uneven load, frequent start-up and working in high temperature environment should be slightly higher.
To sum up, the reducer should use high-grade lubricating oil with appropriate viscosity. For low-speed heavy-duty reducer, extreme pressure heavy-duty gear oil with high viscosity should be selected as far as possible, because it has better extreme pressure anti-wear, thermal oxidation stability, anti-corrosion, anti rust and excellent anti emulsification performance than medium load gear oil, so it is easy to form chemical film on the meshing surface of gear, so as to protect the surface of gear teeth, Reduce the wear of reducer as much as possible.
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