Which bearing type must be continuously lubricated by pressure oil?

Which bearing type must be continuously lubricated by pressure oil?

• A. Plain
• B. Ball
• C. Roller
• D. Journal

Answer: (A)

Plain bearings rely on a continuous film of lubricant between sliding surfaces to prevent metal-to-metal contact. Because the surfaces slide against each other, this film must be maintained at all times, which is achieved by delivering oil under pressure. The pressurized oil not only forms and sustains the lubricating film but also helps carry away heat generated by sliding motion, protecting the bearing from overheating and wear. In contrast, rolling-element bearings like ball or roller types use discrete rolling surfaces, and while they can be lubricated by oil or grease, they do not depend on a continuously pressurized oil film in the same way. Journal bearings are essentially a type of plain bearing, so they share the same lubrication requirement.

Plain bearings rely on a continuous film of lubricant between sliding surfaces to prevent metal-to-metal contact. Because the surfaces slide against each other, this film must be maintained at all times, which is achieved by delivering oil under pressure. The pressurized oil not only forms and sustains the lubricating film but also helps carry away heat generated by sliding motion, protecting the bearing from overheating and wear. In contrast, rolling-element bearings like ball or roller types use discrete rolling surfaces, and while they can be lubricated by oil or grease, they do not depend on a continuously pressurized oil film in the same way. Journal bearings are essentially a type of plain bearing, so they share the same lubrication requirement.