Needle bearings are roller bearings with cylindrical rollers, which are both thin and long relative to their diameter. This roller is called a needle roller. Although it has a small cross section, the bearing still has a high load bearing capacity, the needle bearing is equipped with a thin and long roller (roller diameter D≤5mm, L/D≥2.5, L is the length of the roller), so the radial structure is compact, its inner diameter size and load capacity are the same as other types of bearings, and the outer diameter is the smallest, especially suitable for radial installation size limited support results. According to the different occasions, bearings or needle roller and cage components without inner rings can be selected, and the journal surface and shell hole surface matched with the bearing are directly used as the inner and outer rolling surface of the bearing. In order to ensure that the load capacity and operating performance are the same as that of the bearing, the hardness, processing accuracy and surface quality of the shaft or shell hole raceway surface should be similar to the raceway of the bearing ring. Such bearings can only bear radial loads. The needle bearing with a stamped outer ring is a needle roller bearing with a thin stamped outer ring. The large size series of needle bearings have annular lubrication grooves and lubricating oil holes on the outer ring.
RNA type: The true bearing without inner ring is directly in contact with the journal surface, but the surface hardness and dimensional accuracy of the journal are required to meet the corresponding technical requirements of the bearing raceway.
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