Tool and tool holder for hand-tool apparatus

摘要

The shank (9) of the drill or chisel has two diametrically opposite driving slots (10) with an open end and two diametrically opposite locking slots (11) with both ends closed. To raise the level of torque that can be transmitted to the tool, there are also two diametrically opposite extension slots (12) which lie within the cross-section of the locking slots and extend beyond them. The extension slots are open at the free end of the shank and are engaged by driving keys in the spindle socket. The extension slots are offset by an angle (a) from the axis of symmetry of the locking slots, and the driving flank (12a) is straight and tangential to the curved floor of the locking slot.