In oiliness-lubricated bearings________________?
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Answer: C. do not require external supply of lubricant
Explanation
Oiliness-lubricated bearings rely on specialized boundary lubrication properties of certain organic lubricants. These boundary films adhere strongly to metal surfaces, reducing friction during low-speed sliding contact. Because boundary films protect surfaces directly, these bearings do not require external pressurized lubrication supplies. Lubrication regimes range from hydrodynamic fluid film to boundary lubrication under high loads or low speeds. Oiliness agents are polar compounds added to mineral oils to enhance surface adhesion and film strength. Boundary lubrication prevents scuffing and wear when continuous hydrodynamic oil wedge pressures cannot form.
Machine tool slide ways and lightly loaded pivots frequently utilize oiliness-lubricated bearing designs. Applications experiencing intermittent motion benefit from boundary-lubricated bearings requiring minimal maintenance. Porous sintered bronze bushings often operate effectively on oiliness principles without external oil pumps. Hydrodynamic journal bearings generate oil film pressure exclusively through high-speed shaft rotation. Hydrostatic bearings require continuous external high-pressure oil pumps to maintain separation gaps. Claiming bearings require no external lubricant ignores the ongoing need for initial oil impregnation or grease.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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