Gear lubricants operating temperature

Holinski, R., Dynamics of Boundary Layers, Lubric. Eng., 36, 530, (1980). Gresty, D.A., Kunz, E.J. and Risdon, T. J., The Effect of MoSj Based Lubricants on Automotive Gear Efficiency and Operating Temperatures, SAE Passenger Car Meeting, Detroit, (Sept. 1977). SAE Preprint No. 770834. 

Synthetic shock loading Heavy or shock loading Heavy or use by most OEMs, especially at operating temperatures exceeding 82°C Preferred for shock loading Heavy or must contain extreme pressure additives Gear lubricant... 

API GL-2 Lubricants intended for automotive worm gear axles operating under such conditions of load, temperature and sliding velocity that lubricants satisfying API GL-1 service will not suffice. Products suited for this type of service contain anti-wear additives or film-strength improvers specifically designed to protect worm gears. 

Under ideal conditions gear teeth operate with films which effectively separate the surfaces, and the above EHL film formula may be used. However, under demanding conditions of low speed or high temperature, the film predicted by classical EHL theory may be small compared with the roughness present on the teeth. The gears then operate under conditions described as "partial", "mixed" or "micro" EHL. A conventional measure of the severity of lubrication is provided by the lambda-ratio, which is defined as the mean oil film thickness divided by the combined RMS roughness of the two surfaces, i.e. 

The lower cost dialkyl benzenes are used in a wide variety of industrial and metalworking products. In particular, their sulphur-free chemistry has led to extensive use as rolling and drawing oils for copper. The synthesised alkyl benzenes, even when their chemistry is optimised, generally exhibit poorer properties than PAOs. However, their excellent solvency and low pour point make them suitable for lubricants designed for extremely low-temperature operations in arctic greases, gear oils, hydraulic and power transmission fluids. 

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