What fundamental characteristics must the oil used to lubricate the gearbox gears have?

Question

DentroTest · Accepted Answer

The lubricant used in the gearbox (gear oil or transmission oil) is subjected to intense working loads because of the direct contact between the teeth of the gears. For this reason, it must have sufficient viscosity and consistency to prevent the protective film from breaking under high pressures, thus reducing friction and preventing premature wear of the metal components. A high acidifying power with a low viscosity index is a mistake, because the acidity would corrode the internal parts and a viscosity that is too low would be unable to maintain lubrication under mechanical stress. Having additives only for high temperatures is also a mistake, because low temperatures also negatively affect the fluidity of the oil, making it thicker and hindering cold lubrication and the smoothness of gear changes.

What fundamental characteristics must the oil used to lubricate the gearbox gears have?

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