Issue link: http://read.dmtmag.com/i/859318
Gear Lubricants Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Important Gear Lubricant Properties Transmitted Power Based on the type of gear and amount of power and load that it is expected to handle, lubricant choice should take into account the appropriate increase in temperature. Gear sets that transmit more power tend to run hotter than their smaller counterparts. is additional heat should not be a problem if the operating temperature was properly calculated and an adequate viscosity was chosen based on that temperature. Surface Finish e relative roughness of the gear surface is another determinate of gear lubricant viscosity. Rougher surfaces need heavier viscosities to maintain adequate film strength. It is sometimes recommended to choose a viscosity based on the average smoothing that can take place as the gear is operated. Load Characteristics Before choosing a gear lubricant, it is necessary to evaluate the type of loads the gear will be expected to handle. Excessive loading and/or shock loads require the use of extreme pressure lubricants. In cases of severe loading, as with automotive hypoid gears, metal-to-metal contact cannot be avoided and special extreme pressure lubricants are needed to prevent welding. Drive Type Engines that produce varying amounts of torque typically require a higher viscosity lubricant to assure film strength. Application Method How the lubricant comes in contact with the gear set affects the lubricant choice. Splash-lubricated units require a higher viscosity lubricant to help the oil stay in the gear and maintain film thickness. A pressure- applied lubricant tends to distribute the oil uniformly, removing more heat than a splash-applied lubricant. A heavier viscosity lubricant is not typically necessary in a pressure system. Water Contamination Steam, condensation or cooling effects can result in water contamination in an enclosed gear set. In cases where water contamination is probable, a lubricant with good demulsibility (the ability to separate water and oil) is required. It is of critical importance that the oil's demulsibility characteristics do not fade aer the oil is in service or has become oxidized. Water in dirty oil that can no longer demulsify can cause excessive wear to gears and bearings. A lubricant with good rust and corrosion inhibitors is also necessary to prevent gear and bearing surfaces from rusting in the presence of water. Other Qualities In gears that experience heavy leakage, a special lubricant that resists leakage may be specified. Other desirable lubricant qualities include foam resistance and oxidation resistance. ese qualities help to assure oil quality during periods of extreme service. E10 ecastrof