The NA Series refers to a type of needle roller and cage assembly, which represents the most fundamental and common form of a needle roller bearing. It consists solely of a precision-engineered cage that retains a full complement of needle rollers. Crucially, it does not include an inner or outer ring. This design achieves the smallest possible radial cross-section for a given shaft diameter and housing bore. However, because the assembly lacks rings, the hardened and ground shaft must serve as the inner raceway, and the hardened housing bore must serve as the outer raceway. The NA series is the standardized designation for this type of component, prized for its extreme radial compactness and high load-carrying capacity within a minimal space.
