What defines the term 'ring gap' in piston rings?

The term 'ring gap' refers specifically to the allowable space between the ends of the piston ring when it is installed in the cylinder bore. This gap is crucial for the proper functioning of the piston rings, as it allows for thermal expansion of the ring material as the engine operates and maintains adequate sealing between the piston and cylinder wall. A properly sized ring gap helps to ensure that the rings can accommodate thermal and mechanical changes without affecting engine performance or leading to excessive blow-by, which can decrease efficiency and power.

In contrast to this, the spacing between rings pertains to how the rings are arranged on the piston rather than the gap of a single ring. The distance between the cylinder wall and the piston is related to clearances but does not define the gap of the ring itself. Lastly, the thickness of the piston rings is about the physical dimensions of the ring material and not the separation between their ends. Understanding the concept of ring gap is essential for ensuring optimal performance and longevity of an engine.