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Four Types of Gear Oils

February 01, 2013
Jean Van Rensselar
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R&O INHIBITING GEAR OILS. Rust and oxidation (R&O) inhibiting gear lubricants perform well over a range of gear sizes, speeds and outside temperatures. They lubricate well if both the gears and bearings are lubricated from the same reservoir. Because they do not adhere to the gear tooth surface, it’s best if the gear teeth are constantly relubricated. R&O inhibiting gear oils can be conditioned with heat exchangers and filters for consistent temperature and cleanliness.

EP GEAR OILS. Extreme-pressure (EP) gear oils are recommended for gear drives subjected to conditions of high load, medium-to-high slide and high-power transmit. EP gear oils can contain additives that are corrosive to brass and bronze components. But EP gear oils that utilize chemistries noncorrosive to these components are available. These oils also perform well over a range of gear sizes and speeds and outside temperatures. Gear teeth must be continually relubricated.

COMPOUNDED GEAR OILS. Compounded gear oils lubricate gear drives where the high sliding of gear teeth requires a friction-reducing agent to minimize heat and improve efficiency (enclosed worm gear drives). Unlike R&O and EP oils, they do not perform well over a wide temperature range and have a high operating temperature of 180 F (82 C). Like R&O and EP oils, constant relubrication of the gear teeth is encouraged.

SYNTHETICS. Synthetic gear oils are primarily used in applications where mineral-based industrial gear oils are unable to perform. Synthetic gear lubricants can contain R&O inhibitive additives and/or EP additives. Synthetic gear lubricants offer advantages such as improved thermal and oxidation stability, lower volatility and evaporation rates, improved energy consumption and reduced flammability.

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