Oilers/Plant Tenders (HHC) Civil Service Practice Exam

What is the primary purpose of seals in machinery that close openings between shafts and housings?

1. Enhance performance

2. Reduce weight

3. Exclude dirt and prevent the escape of lubricant

4. Improve aesthetic design

The correct answer is: Exclude dirt and prevent the escape of lubricant

The primary purpose of seals in machinery that close openings between shafts and housings is to exclude dirt and prevent the escape of lubricant. Seals serve a critical function in maintaining the integrity of machinery by ensuring that lubricant, which is essential for reducing friction and wear between moving parts, remains contained within the system. This containment not only enhances the efficiency of the machinery by providing necessary lubrication but also minimizes the risk of contaminants, such as dirt and debris, entering the system, which can lead to premature wear and potential failure of the equipment. In contrast, while enhancing performance may be a secondary benefit of effective sealing, it is not the primary function. Similarly, weight reduction is not a direct purpose of seal applications, as the materials chosen for seals are selected based on their functionality rather than weight considerations. Lastly, improving aesthetic design does not relate to the seals' operational role, which focuses on functionality over appearance. Thus, the sealing component of machinery is vital for its longevity and effectiveness, with the key role of protecting internal lubricants and mechanical components from contamination and loss.