Purchasing gear lubricants: be careful when playing the numbers game
Written by John Sander
6. Minimize Effects of Operating Environment
A gearbox could be operating in an environment that is hot, cold, dusty, wet or various combinations of these conditions, all of which can have significant effects on the gearbox. To minimize these effects, you can take precautions such as using air breathers, sight glasses and filtration devices. The lubricant itself also may be required to compensate for some of the challenges caused by the operating conditions.
Extreme Temperatures
For an application operating at either extremely high or low temperatures, it may be necessary to choose a synthetic-based lubricant instead of a mineral-oil-based lubricant. For low temperatures, oil should have a pour point that is 5°C (9°F) below the startup temperature. Operating temperatures can also determine the chemistry needed in the gear oil. Very aggressive EP gear oils might result in heavy deposit formation in the gearbox during operation. Non-EP oil used in an EP oil application can result in high oil temperatures due to excess frictional heating of the oil.
Particulate Contamination
In a coal or rock crushing plant, it is inevitable that dust and dirt will be in the air, and it is very difficult to keep the particles from finding their way into the gear oil. Filterable gear oil would allow filtration to remove harmful contaminants without removing valuable additives.
Water Contamination
In water treatment facilities, it is nearly impossible to keep water out of some gearboxes, making it extremely important to choose a gear lubricant with excellent water separation properties.
