Needle Bearings: Technical Characteristics​

Needle bearings are roller bearings equipped with cylindrical rollers. Relative to their diameter, the rollers are both thin and long—these rollers are referred to as "needles." Despite their small cross-section, the bearings still offer high load-carrying capacity.​

Needle bearings are fitted with thin and long needles (with roller diameter D ≤ 5mm and length-diameter ratio L/D ≥ 2.5, where L denotes the roller length). This design results in a compact radial structure: when the inner diameter size and load capacity are the same as those of other bearing types, needle bearings have the smallest outer diameter. They are particularly suitable for support structures where radial installation space is limited.​

Depending on the application scenario, needle bearings without an inner ring or needle-and-cage assemblies can be selected. In such cases, the journal surface and housing bore surface matched with the bearing directly serve as the inner and outer rolling surfaces of the bearing. To ensure the load capacity and operating performance are consistent with those of bearings with rings, the hardness, machining accuracy, and surface quality of the shaft or housing bore raceway surfaces should be comparable to those of the raceways of bearing rings. This type of bearing can only withstand radial loads.