The long cylindrical roller bearing has a small volume, light weight and a large radial load capacity. As viewed from its structre, it is suitable for the medium and high speed rotaions. Ordianrily without the inner ring,but with the cage.Suitable in the supporting structures whose radial installation dimensions are restricted, the axle neck surface matched with bearing directly taken as the rolling suface. Generally used in the place of the axle head of the gear hydraulic pump.