Pull studs The pull stud allows the locking drawbar of the spindle to pull the toolholder firmly into the spindle and to release the toolholder automatically. Pull studs are made in various styles and sizes. They are not necessarily interchangeable. Only use the pull studs that are specified by the machine tool manufacturer. Locking Drawbar Pull Stud Clamping Unclamping Recommended torque for pull stud tightening: SK / BT / ISO 30  20 Nm SK / BT / ISO 40  50 Nm SK / BT / ISO 50 100 Nm 14 2020 14.30