The invention relates to a needle-free injection system (1) with an active substance cartridge (10) comprising a nozzle (100) and a plunger-actuated metering chamber (101) for dispensing an active substance (2) under pressure. The injection device (1) comprises a housing (11) with a receptacle (110) for accommodating the active substance cartridge (10) and a plunger (12) that is movable relative to the housing (10) and is designed to carry out a movement for ejecting the active substance (2) from the active substance cartridge (10), a mechanism (13) is provided for driving the plunger (12) and the plunger (12) has a starting position in relation to the mechanism (13), from which the piston (12) is released to move by means of a trigger (14). The mechanism (13) is designed to allow the piston (12) to return to the starting position. The discharged amount of active substance (2) is adjustable. In order to carry out quickly multiple successive injections or applications of limited discharged amounts, a mechanism for tensioning the mechanism for driving the plunger is integrated in the injection system. The receptacle (110) of the active substance cartridge (10) is adjustable in the longitudinal direction relative to the piston (12) in order to adjust the discharged amount, a locking profile (120) and a corresponding locking member (112) limiting the maximum thrust length of the piston (12) (maximum metered amount).
