How much oil is recommended to lubricate a ball bearing?

The correct approach to lubricating a ball bearing is to ensure that the lubrication allows for efficient operation while avoiding excess oil, which can lead to overheating and reduced performance. Covering halfway up the bottom rolling element strikes a balance; it provides adequate lubrication without overfilling. This method allows for the necessary distribution of oil during rotation as the rolling elements pass through the lubricant.

Proper lubrication is crucial because it helps reduce friction, protects against wear, and dissipates heat. However, if a bearing is overfilled, the excess oil can create turbulence, leading to ineffective lubrication and potential damage.

In contrast, covering the entire bearing or just the outer race does not provide optimal lubrication. Overfilling can lead to problems, while insufficient oil on the rolling elements can result in inadequate protection and increased friction. Therefore, the recommended method of filling halfway up the bottom rolling element is a well-established practice to ensure longevity and reliability in bearing operation.