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Transmission lubricant transformed
| 题名： | Transmission lubricant transformed |
| 正文语种： | eng |
| 摘要： | While most engineers will be familiar with the viscosity grades and ACEA sequences for engine oils, transmission lubricants exist in a parallel universe where nothing is quite the same. Unsurprising really, as engine oils need to cope with the high temperatures and contaminants produced by combustion, while transmissions require varying properties depending on whether they are used in an (automated) manual gearbox (with or without synchromesh), an automatic transmission, or a drive axle. Even the way in which viscosity is measured is different. The lower 'W number on multigrade engine oils is determined by a cold cranking test simulating an engine start at winter temperatures, while the higher number denotes its viscosity at operating temperatures. By contrast, gear oil viscosity is measured after the oil has been held at temperatures of-40℃to-12℃ (depending upon grade) for 16 hours by the Brookfield Test, which measures the torque required to shear the oil. Clive Webber, technical support chemist at Texaco Lubricants, explains: "Some otherwise acceptable gear oils could crystallise if exposed to prolonged cold temperatures, hence the 16-hour chill before testing." |
| 出版年： | 2022 |
| 期刊名称： | Transport engineer |
| 期： | Mar. |
| 页码： | 22-23 |
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