A SHIELD TRIGGER MECHANISM AND AN INJECTION DEVICE WITH A SHIELD TRIGGER MECHANISM

The invention relates to a spring driven injection device for expelling doses a liquid drug. A housing structure secures a container containing a liquid drug to be injected via a spring driven dose engine. A needle shield is rotatably relatively to the housing structure between a locked position and an unlocked position. In the locked position the needle shield is prevented from axial movement and in the unlocked position axially movement is possible by applying an axial force onto the needle shield. Axial movement of the needle shield activates the spring driven dose engine to automatically eject the dose of the liquid drug from the container. The needle shield is rotational guided from the locked position to the unlocked position in a track arrangement which is further configured to prevent the needle shield in rotation from the locked position to the unlocked position during application of the axial force to the needle shield.