Self-aligning ball bearings have two trains gangqiu, inner circle have two groove, outer ring groove shape, have for internal spherical automatically adjustable heart performance. Can automatic compensation because axis around the song and shell the coaxial tolerance of deformation error generated, suitable for supporting seat hole cannot guarantee the coaxial tolerance of the component strictly. The main bear radial load bearing race in bear radial load at the same time, can also withstand a small amount of axial load, don' t usually used to withstand pure axial load, such as inherit pure axial load, only a list of steel ball bearing.