What effect does running clearance have on lubrication?

Running clearance plays a crucial role in the lubrication of machinery and engine components. The clearance between moving parts affects how well the lubricant can form a film between them. If the running clearance is too tight, it can lead to inadequate lubrication because the lubricant cannot circulate properly; this can increase friction and wear on the surfaces. On the other hand, if the clearance is too large, it can result in excess lubricant being required, which could lead to inefficiencies as well.

In this context, the choice that describes the impact of running clearance most accurately indicates that it can decrease lubrication efficiency. This occurs because insufficient or excessive clearance can hinder the ideal flow and distribution of the lubricant necessary for effective performance. Proper running clearance is essential to ensure that lubricants can effectively minimize friction and wear, thus maintaining the longevity and efficiency of the machinery involved.