Patent ID: 8882721

Claim:
A drive assembly for use in a drug delivery device, the drive assembly comprising: a housing having a proximal end and a distal end; an axis extending between the proximal end and the distal end; at least one drive member; a piston rod adapted to be driven along the axis by the drive member; and an indicator adapted to provide positional information about a position of the piston rod relative to the proximal end, wherein the indicator and the piston rod are configured to convert movement of the piston rod with respect to the housing into a rotational movement of the indicator, and the indicator comprises a rotation member configured to convert movement of the piston rod into the rotational movement of the indicator with the indicator being coupleable to the piston rod via the rotation member and wherein at least a part of the rotation member is arranged within the piston rod, characterized in that the rotation member runs from outside of the piston rod to inside of the piston rod through an opening of the piston rod, the opening being provided on that side of the piston rod that faces the proximal end.