Injector device and method for its operation

Injector device for a syringe container, which syringe container comprises a barrel of axially substantially constant cross-section, a front opening and at least one container movable wall inserted in the barrel for displacement of a container content, the injector comprising a) a housing or housing part arranged to receive the container at least axially stationary, b) an integral or composite piston rod arrangement operable to displace the container movable wall at least in the forward direction, and c) a track system adapted to control or sequence the piston rod movements, the track system comprising at least one cooperating track and follower, the cooperating track and follower being arranged stationary with respect to the housing and the piston rod respectively, or vice versa, and in cooperation adapted to allow at least one forward movement of the piston rod, wherein the track system comprises a joining track running at least partly transversal to the axial direction, and at least two expelling tracks, each with a first end being connected to the joining track, adapted to allow the follower to selectively enter into any one of the expelling tracks, each expelling track running at least partly in the axial direction and in cooperation with the follower adapted to allow forward movement of the piston rod, and

• wherein each of at least two of the expelling tracks continues toward its second end in a first axial section, a knee or branch, and a second axial section transversely offset from the first axial section.