A drug delivery device (200, 300) comprising or adapted to receive a drug-filled cartridge, comprising: - a housing (201, 301), - an expelling assembly comprising: - a piston rod adapted to engage and axially displace a piston in a received cartridge in a distal direction to thereby expel a dose of drug from the cartridge, - a drive member (260, 360) defining an axis, - a spring housing (250, 350), - a torsion drive spring coupled to the spring housing respectively the drive member, - dose setting means allowing a user to simultaneously set a dose amount to be expelled and strain the drive spring correspondingly by rotation of the drive member, comprising: - a dose setting member which during dose setting is rotationally coupled to the drive member and adapted to rotate in a first direction to set a dose, and - a ratchet mechanism allowing the drive member to be held in a set rotational position against the bias of the strained drive spring, - release means adapted to release the strained drive spring to rotate the drive member to expel the set dose amount, the release means comprising a release member (290, 390) being axially moveable relative to the housing between a proximal initial position and an actuated distal release position, characterized in that - the spring housing is helically coupled to the housing, the spring exerting a tangential force on the spring housing to thereby bias the spring housing in the proximal direction, - the spring housing exerts a proximally directed biasing force on the release member when actuated, and - the spring housing can be moved helically in the distal direction when a distally directed force is exerted on the release member. - a housing (201, 301), - an expelling assembly comprising: - a piston rod adapted to engage and axially displace a piston in a received cartridge in a distal direction to thereby expel a dose of drug from the cartridge, - a drive member (260, 360) defining an axis, - a spring housing (250, 350), - a torsion drive spring coupled to the spring housing respectively the drive member, - dose setting means allowing a user to simultaneously set a dose amount to be expelled and strain the drive spring correspondingly by rotation of the drive member, comprising: - a dose setting member which during dose setting is rotationally coupled to the drive member and adapted to rotate in a first direction to set a dose, and - a ratchet mechanism allowing the drive member to be held in a set rotational position against the bias of the strained drive spring, - release means adapted to release the strained drive spring to rotate the drive member to expel the set dose amount, the release means comprising a release member (290, 390) being axially moveable relative to the housing between a proximal initial position and an actuated distal release position, - a piston rod adapted to engage and axially displace a piston in a received cartridge in a distal direction to thereby expel a dose of drug from the cartridge, - a drive member (260, 360) defining an axis, - a spring housing (250, 350), - a torsion drive spring coupled to the spring housing respectively the drive member, - dose setting means allowing a user to simultaneously set a dose amount to be expelled and strain the drive spring correspondingly by rotation of the drive member, comprising: - a dose setting member which during dose setting is rotationally coupled to the drive member and adapted to rotate in a first direction to set a dose, and - a ratchet mechanism allowing the drive member to be held in a set rotational position against the bias of the strained drive spring, - a dose setting member which during dose setting is rotationally coupled to the drive member and adapted to rotate in a first direction to set a dose, and - a ratchet mechanism allowing the drive member to be held in a set rotational position against the bias of the strained drive spring, - release means adapted to release the strained drive spring to rotate the drive member to expel the set dose amount, the release means comprising a release member (290, 390) being axially moveable relative to the housing between a proximal initial position and an actuated distal release position, - the spring housing is helically coupled to the housing, the spring exerting a tangential force on the spring housing to thereby bias the spring housing in the proximal direction, - the spring housing exerts a proximally directed biasing force on the release member when actuated, and - the spring housing can be moved helically in the distal direction when a distally directed force is exerted on the release member.