Medical delivery device with axially expandable drive member

A medical delivery device for advancing a piston in a medication container to expel a medication. A support structure supports the container and a drive assembly that advances the piston. The drive assembly includes a drive belt that can be retracted and extended. The retracted ribbon defines a spiral and the extended ribbon defines a helix. The drive belt can be moved incrementally between the retracted spiral configuration and the extended helical configuration. A mechanical drive rotates the drive belt to selectively extend and retract the belt. A thrust member having a helical ramp engages a proximal edge of the drive belt where it transitions between a spiral and a helix. A support member at the distal end of the drive belt exerts an axial force on the piston when the belt extends. (Automatic translation with Google Translate, without legal value)