Deep-groove ball bearings have simple structure,and convenient to use,it is produced in the largest number and also is that kind of bearings which are used most widely.This kind of bearing mainly takes radial loads ,and can also take moderate axial loads.When the radial windage is becoming bigger,it has the function of an angular contact ball bearing,and also can take higher axial loads.Compare wiht other types of bearings whice have the same size,it has low friction coefficient ,high limit rotational speed.When the rotational speed is high and not allowed to used thrust ball bearing,we can choose this kind of bearing to take simple axial loads.