Drive mechanism for a drug delivery device

A drive mechanism for a drug delivery device, comprising:

• a body having a distal end and a proximal end, which are spaced apart in the direction of an axis,
• a lead screw arranged within the body along the axis, the lead screw being movable relatively to the body,
• a lead screw nut,
• the lead screw comprising a screw thread and
• the lead screw nut comprising a drive feature coupling the lead screw and the lead screw nut, so that the lead screw is helically rotatable in the lead screw nut,
• the lead screw comprising a stop features interfering with a rotation of the lead screw and the lead screw nut relative to one another when a force is applied to the lead screw in the proximal direction,
• the body comprising a guide that restricts a movement of the lead screw nut,
• the lead screw nut comprising a surface area facing the guide, the surface area comprising a slope varying around the axis, and
• the screw thread, the slope, and the guide interacting in such a manner that the lead screw nut rotates in a first direction when a force is applied to the lead screw in the proximal direction.