双列圆柱滚子轴承：这类轴承能承受较大的径向载荷并允许有较高的转速。轴承

Double row cylindrical roller bearings: These bearings can withstand greater radial load and allows a higher speed. Two bearing rollers are arranged to intersect, the rotational fluctuation frequency than the double row bearings, the amplitude is reduced by 70%. Such bearings are commonly used in two forms: NN30 / W33, NN30K / W33 with two series of bearing inner wall, outer separable; NNU49 / W33, NNU49K / W33 bearing outer ring with two series of ribs, the separable ring, wherein NN30K / W33 and NNU49K / W33 series tapered inner bore (taper 1:12), cooperating with the conical journal shaft, axial movement of the inner ring, the inner ring can swell to reduce small bearing clearance or even preload the bearings. Cylindrical bore bearing usually shrink fitting, using an interference fit to reduce the bearing clearance or preload to achieve the purpose. NNU49 series of detachable inner bearing inner ring mounted on a spindle in general made after finishing the raceway, to obtain a high precision spindle rotation

Double column cylindrical roller bearings: These bearings can withstand large radial loads and allow for higher speeds. The two rollers in the bearings are arranged in a cross-cutting manner, and the frequency of fluctuations can be doubled and the amplitude is reduced by 70% compared to the single-row bearings. Commonly used for this type of bearing in two forms: NN30/W33, NN30K/W33 two series bearing inner ring with retaining edge, outer ring can be separated; Detachable, wherein NN30K/W33 and NNU49K/W33 series inner ring for the cone hole (taper 1:12), with the spindle of the tapered shaft neck, axially moving the inner ring, can make the inner ring swell, in order to reduce bearing clearance and even pre-tighten bearings. Cylindrical hole bearings are usually thermally fitted, using over-the-top mates to reduce bearing clearances or to achieve pretension. NNU49 series bearings for the internal ring separable, generally after the inner ring is installed on the spindle and then finishing the raceway, in order to obtain high spindle rotation accuracy

Double row cylindrical roller bearing: this kind of bearing can bear larger radial load and allow higher speed. The two rows of rollers in the bearing are arranged in a cross way. When rotating, the fluctuation frequency can be twice as high as that of a single row bearing, and the amplitude can be reduced by 70%. There are two types of commonly used bearings: NN30 / W33 and nn30k / W33. The inner ring of the two series of bearings has a stop edge, and the outer ring can be separated; nnu49 / W33 and nnu49k / W33 have a stop edge, and the inner ring can be separated. The inner rings of nn30k / W33 and nnu49k / W33 series are taper holes (taper 1:12), which are matched with the tapered Journal of the main shaft. Axial movement of the inner ring can make the inner ring swell, so as to reduce the shaft diameter Bearing clearance and even pre tighten the bearing. Cylindrical bore bearings are usually hot installed, and interference fit is used to reduce bearing clearance, or to achieve the purpose of preloading. For the nnu49 series bearings with separable inner ring, the main shaft is usually installed on the inner ring and then the raceway is finished to obtain high rotation accuracy of the main shaft<br>