With thin and long roller (roller diameter in length from 3 to 10 times the diameter of generally not more than 5mm), so the radial structure is compact, its internal diameter size and load bearing capacity and other types of the same outer diameter of the small, especially for radial bearing mounting dimensions restricted results. Depending on different occasions, the choice of the bearing inner ring or needle-free and cage assembly, this time with the journal bearing surface and matching shell hole .Bearing directly on the surface as the inner and outer rolling surface, in order to ensure the load capacity and operating performance and a ring bearing the same roller shaft or housing bore .Road surface hardness, machining accuracy and surface quality should be with the bearing ring similar to the raceway. Such bearings can only bear radial load.