Drive assembly, piston rod, drug delivery device, and use of a spring

摘要

The drive assembly may comprise a housing (10A, 10B, 10C), a piston rod (20) being axially displaceable and rotatable with respect to the housing, a drive member (30) being axially displaceable, and a rotational bias member (50) being operable to transfer a resilient bias to the piston rod. The drive assembly may be configured such that, for setting a dose, the drive member is proximally axially displaceable with respect to the housing and the piston rod from a rest position to a dose set position. When setting the dose, the piston rod may be rotated in a first rotational direction and, subsequent to the rotation in the first rotational direction, rotated in a second rotational direction with respect to the housing and the drive member. Further, a piston rod and a use of a spring (80) are provided for.