Taper roller bearings have tapered cone and cup between which taper rollers are arranged. The extension lines of them intersect at one point of shaft axis; therefore, pure rolling on the raceway can be achieved. Taper roller bearings are separable. Bearing cone (including roller, cage and inner ring) and cup (outer ring) can be separated, therefore, it can be easily assembled on the bearing journal and bearing block. Taper roller bearings are able to accommodate radial loads, unidirectional axial loads and combined loads of radial and axial. The axial load carrying capacity of taper roller bearings is largely determined by the contact angleα, which corresponds to the raceway angle of the cup, the larger the contact angleα, the higher the axial load carrying capacity is. Generally, taper roller bearings do not allow any angle error, but the surface of roller and raceway can allow 2′~4′ angle error after a special design.