A drive assembly for use in a medication delivery device (1) is provided for, which comprises a housing (3) having a proximal end and a distal end, a drive member (20) moveable in the proximal direction with respect to the housing for setting a dose of the medication to be delivered and in the distal direction with respect to the housing for delivering the dose, a piston rod (11) adapted to be driven by the drive member in the distal direction with respect to the housing during movement of the drive member in the distal direction for delivering the dose and a restriction member (10) for restricting proximal movement of the piston rod with respect to the housing during proximal movement of the drive member by mechanical interaction of the restriction member with a stop feature (12a) of the piston rod, wherein the restriction member and the stop feature are arranged for the piston rod to be moved proximally a first distance during a first proximal movement of the drive member before the restriction member and the stop feature interact mechanically, wherein the first distance which the piston rod moves proximally during the first proximal movement of the drive member is larger than a subsequent distance which the piston rod moves proximally during a subsequent proximal movement of the drive member.Linvention concerne un ensemble actionnement sutilisant dans un dispositif (1) dadministration de médicament et qui comprend un corps (3) présentant une extrémité proximale et une extrémité distale, un élément dactionnement (20) pouvant être déplacé dans la direction proximale par rapport au corps afin détablir une dose du médicament à administrer, et dans la direction distale par rapport au corps pour administrer la dose une tige de piston (11) conçue pour être actionnée par lélément dactionnement dans la direction distale par rapport au corps, pendant le déplacement de lélément dactionnement dans la direction distale, afin dadministrer la dose et un élément de limitation (1
