NATO and Russia have resumed military contacts, which were cut off after the war in Georgia, and the two sides have agreed to a joint review of "21st-century threats".

In three overlapping circles, three round shapes overlap after the joint and overlap are preserved, only two circles overlap area have been cut off hollow out (figure 3).

The reasons for error cut-in grinding of cage spherical outside surface of ball basket constant velocity joint is analyzed, and the solution for the problem is put forward.