The invention refers to an auto-injector comprising:a body, a syringe with a hollow injection needle and a stopper, wherein the syringe is slidably arranged with respect to the body,a torsion spring capable of, upon activation:pushing the needle from a covered position inside the body into an advanced position through the orifice and past the proximal end (P),operating the syringe to supply the dose of medicament (M), andactivating means arranged to lock the spring means in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring means for injection,wherein the torsion spring is grounded at one end in the body and at the other end in a first gear member rotatable about a longitudinal axis, wherein the first gear member, upon rotation, is arranged for translating a second gear member toward the proximal end (P), the second gear member prevented from rotating and arranged to be coupled to the stopper in order to push it towards the proximal end (P), wherein the first gear member is engaged with the activating means prior to manual operation in a manner to prevent rotation and disengaged from the activating means upon manual operation,characterized in that a ratchet wheel is arranged on the first gear member, the ratchet wheel having a number of circumferentially arranged teeth, wherein the activating means comprise at least one locking feature for engaging the ratchet wheel in a manner to prevent rotation and wherein the locking feature is arranged to allow rotation on manual operation.
