1. According to the shape of the bearing seat: 1.1 The outer spherical seated bearing, also called the bearing unit (SKF parlance). When there is no bearing, it is called an outer spherical bearing seat. 1.1.1.1 The outer spherical bearing seat is divided into 200 series according to the bearing series. 500 series. 300 series. 600 series. XOO series. 1.2 The outer spherical bearing seat is divided into vertical seat (P seat), square seat (F seat), diamond seat (FL seat), round seat (C seat), convex round seat (FC seat), convex Table square seat (FS seat), dark hole seat (PA seat), hanging seat (FA seat). 1.3 Integral (that is, non-separable) vertical bearing seat assembly, with screw-fastened bearing box cover. These vertical bearing block sets were originally developed as axle boxes for light rail trucks, but they can also be used in traditional vertical bearing block sets. Non-separable vertical bearing seat assemblies have higher rigidity than separate bearing seats, and some can withstand heavier loads. The outer spherical bearing seat is also an integral seat. 2 split housing 2.1 Split bearing housings are divided into SN2, 5, 3, and 6 series according to different bearings and shaft requirements. SNL2, SNL5, SD have 2, 5, 3, 6, 3100, 3000, 3200 The bearing seat is divided into: split bearing seat, sliding bearing seat, rolling bearing seat, bearing seat with flange, outer spherical bearing seat and so on.