A crown wheel is assembled onto a differential by means of several bolts in a circular pattern. After scanning the part the spindles are adjusted automatically to the correct center distance for the corresponding pitch diameter of the crown wheel. All bolts are tightenend 2 by 2 in a predetermined sequence. A position detection system checks that both DC tools are only enabled if the 2-spindle unit is in correct position. Torque values from 200 Nm upto 900 Nm depending on the model of crownwheel. Even torque + angle specifications are possible.