An auto Injector (1) to administer a dose of liquid Medicine (m) comprises: an elongate housing (12)； a subset of Carrier comprises a Carrier Tube (7) arranged Sliding inside the casing (12), Carrier (7) is adapted to contain a syringe (3 Hollow) with an injection Needle (4),A Drive Spring (8) and a piston (9) to forward the Spring load impulse (8) to (6) a Cap from the syringe (3),The syringe (3) can hold for the axial Translation together with the carrier (7)； a Spring control (19) provided around the carrier (7) for moving the carrier (7) proximally (P) to advance the Needle (4) Beyond a proximal end the auto Injector (1)； a Shutter Button (13) to release the Spring control (19) in the Actuator.The Boost Spring (8) predisposes the piston (9) proximally (P) against the carrier (7). At least one Spring Arm (15) is available either in the carrier (7) or the piston (9) and a ramp with the other coupling between the carrier (7) and (9) to release the Plunger under the Spring load impulse (8).A pin (14) has to be attached to the housing (12), at least after the actuation of the trigger Button (13) to be placed to withstand the Spring Arm (15) from the Decoupling of the carrier (7) on the piston (9) and thus release the Spring Driving So (8) when the carrier (7) is in a distal position.The Spike (14) are to remain in position when the carrier (7) is transferred to advance the Needle (4) to pull the Spring Arm (15) from the Tang (14) thus allowing the deflection of the Spring Arm (15) due to the coupling under the ramp load d The Boost Spring (8) to decouple the piston (9) of the carrier (7) and release the Spring impulse(8) for the Administration of Drug when the carrier (7) has reached a preset position during the Advancement of the Needle.Un auto-inyector (1) para administrar una dosis de un medicamento líquido (M) comprende: una carcasa alargada (12)； un subconjunto de portador que comprende un portador tubular (7) dispuesto de manera deslizante dentro de la carcasa
