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Jet Lubrication
Jet lubrication is often used for ultra-high-speed bearings, with a dmn value (dm: pitch diameter of rolling element set in mm; n: rotational speed in rpm) exceeding one million such as the bearings in jet engines. Lubricating oil is sprayed under pressure from one or more nozzles directly into the bearing.
The figure shows an example of ordinary jet lubrication. The lubricating oil is sprayed on the inner ring and cage guide face. With high-speed operation, the air surrounding the bearing rotates with it causing the oil to be deflected. The jetting speed of the oil from the nozzle should be more than 20% of the circumferential speed of the inner ring outer surface. More uniform cooling and better temperature distribution are achieved using more nozzles for a given amount of oil. It is desirable for the oil to be forcibly discharged so the agitating resistance of the lubricant can be reduced and the oil can effectively carry away heat.
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