Abstract: An automated collar-forming drill mechanism, having the bottom end of its rotatable drive shaft (1) fitted with a tool head (2), which is driven axially back and forth by means of a piston-cylinder assembly (5-9), the drive shaft (1) extending through its piston rod (9). The axially directed operations of the tool head (2) are effected by means of a pneumatic part of the piston-cylinder assembly and a limitation to the speed of working operations is effected by means of a hydraulic part of the piston-cylinder assembly. The operating speeds upwards and downwards, as well as the reversing points for operating speeds and direction, are adjustable.