NTN needle roller bearings are roller bearings featuring cylindrical rollers that are slender and elongated relative to their diameter. These rollers are termed needles. Despite their small cross-section, the bearings exhibit high load-carrying capacity. Equipped with slender rollers (roller diameter D ≤ 5 mm, L/D ≥ 2.5, where L denotes roller length), needle roller bearings feature a compact radial structure. When their inner diameter and load capacity match those of other bearing types, they possess the smallest outer diameter. They are particularly suitable for support structures where radial installation dimensions are constrained.

Depending on the application, either a bearing without an inner ring or a needle roller and cage assembly may be selected. In such cases, the mating shaft journal surface and housing bore surface directly serve as the bearing's inner and outer rolling surfaces. To ensure equivalent load capacity and operational performance to bearings with rings, the hardness, machining accuracy, and surface finish of the shaft or housing bore raceway surfaces should be comparable to those of the bearing ring raceways. These bearings are designed to accommodate radial loads only.