PULL STUDS The pull stud allows the locking draw bar of the spindle to pull the toolholder firmly into the spindle and to release the toolholder automatically. DIN 69871 Pull studs are made in various styles and sizes. They  Locking Drawbar are not necessarily interchangeable. Only  use  the  pull  studs  that  are  specified  by  the  Pull Stud machine tool manufacturer. ISO 60 Clamping MA S 403 BT Unclamping DIN 2080 HSK-A VDI Recommended torque for pull stud tightening: SK / BT / ISO 30  20~25  Nm SK / BT / ISO 40  60~80  Nm SK / BT / ISO 50 200~250 Nm MORSE 256