Evaluation of Impregnated Lubricants in Ball-Bearing Retainers at 10-6 Torr
NASA technical note
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER
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Four liquid lubricants, a polyphenyl ether, a polysiloxane, a sebacate, and a high-viscosity mineral oil, were evaluated as lubricating impregnants in cotton-cloth phenolic retainers of 20-millimeter-bore ball bearings operating in a vacuum of 10-6 torr. The effect of the cloth weave on the lubricating effectiveness of the best of the lubricants was also studied. The test bearings were run at 3550 rpm under axial loads of 50 to 100 pounds 22.7 to 45.4 kg for 1 hour, or until the torque exceeded and remained above 20 inch-ounces 14.1 cm-N. Although none of the lubricants provided good lubrication in the vacuum environment of this system, the most acceptable lubricant was the mineral oil. It provided the lowest torque levels and torque roughness and carried the maximum load for the full duration of the test. High initial torques occurred frequently with all of the lubricants, which indicated inadequate lubrication during the initial part of the run. Comparing bearing performance obtained with only impregnated retainers to that obtained with both impregnated retainers and prelubrication showed that the impregnated retainers used did not feed the lubricant fast enough to provide good lubrication at the conditions of this investigation. In additional tests with the high-viscosity mineral oil, varying the weave of cloth in the retainer produced no significant improvements in the bearing torque.
- Lubricants and Hydraulic Fluids
- Machinery and Tools