The Z=52 Coupling Box, code 08.10.202, operates when the clutch 08.10.203 is energized with 24 V. By generating an electromagnetic field, it closes and locks the drive plates. The fins on the outer plates, once clamped, engage with the slots of the bell, transmitting the rotation of the threading spindle. The activation command is controlled by a software cam within the program of the Siemens S5 or S7 PLC, which restores the voltage so the machine can prepare for threading the next parts. Threading is performed by chasing (follow threading), and the spindle always rotates in the same counterclockwise direction both when the threading tool enters and when it exits.