The rolling element is a centripetal rolling bearing of cylindrical rollers. The internal structure of cylindrical roller bearings adopts a parallel arrangement of rollers, with spacing retainers or isolation blocks installed between the rollers to prevent tilting or friction between the rollers, effectively preventing an increase in rotational torque. The cylindrical roller and raceway are linear contact bearings. Large load capacity, mainly bearing radial loads. The friction between the rolling element and the collar edge is small, suitable for high-speed rotation. According to the presence or absence of ribs on the ring, it can be divided into single row cylindrical roller bearings such as NU, NJ, NUP, N, NF, and double row cylindrical roller bearings such as NNU and NN. The bearing is a separable structure with inner and outer rings. Cylindrical roller bearings without retaining edges on the inner or outer rings can move relative to the axial direction, so they can be used as free end bearings. A cylindrical roller bearing with double ribs on one side of the inner and outer rings, and a single rib on the other side of the ring, which can withstand a certain degree of axial load in one direction. Generally, steel plate stamped cages or copper alloy solid cages are used. But some also use polyamide shaped cages.