This standard applies to combined bearings installed in components with limited radial dimensions and required to withstand larger radial loads and smaller one-way (or two-way) axial loads.
JB/T 3123-1991 history
2007JB/T 3123-2007 Rolling bearings-Combined needle roller bearings with angular contact ball bearings-Boundary dimensions
1970JB/T 3123-1991 Outline dimensions of rolling bearing combined needle roller and angular contact ball bearing