Oilers/Plant Tenders (HHC) Civil Service Practice Exam

For certain types of bearings, which of the following can be used as a lubricant?

1. Mineral oil

2. Grease only

3. Water

4. Air

The correct answer is: Water

Water can function as a lubricant for specific types of bearings, particularly those designed for submerged or wet environments. These bearings often rely on hydrodynamic lubrication, where a film of water separates the moving surfaces, reducing friction. In applications like water pumps or in environments with high humidity, water can be effective as it is readily available and can cool components while providing lubrication. The other options, while they may be used in various lubrication scenarios, do not generally apply to this specific context. Mineral oil and grease are more traditional lubricants used for a wide range of bearings due to their ability to reduce wear and provide thermal stability, but they are not suitable for all bearing types, especially in environments where water is present. Air can serve to reduce friction in some applications, particularly in air bearings, but it does not offer the same lubrication properties as a liquid or semi-solid lubricant. Therefore, water stands out as a suitable lubricant for certain bearing types.