A method of making an injection device comprising the acts of:
- providing a housing and providing the housing with a body portion with opposed first and second ends and defining first and second openings in the first and second ends and providing the housing with an end cap;
- defining a housing interior in the housing;
- providing a main spring assembly having a main spring and a plate and connecting the main spring to the plate and the main spring abuts against the end cap, and extending first and second support arms from the plate;
- providing a release component with a release ring and a tooth, and wherein the tooth extends from the release ring and the tooth has a sliding surface, and defining first and second release slots in the release component that are sized such that the first and second support arms are capable of sliding through the first and second release slots and wherein the first and second support arms abut against the release ring;
- providing an actuator having an actuator ring and extending a first actuator rod with a first engagement end from the actuator ring, and fitting the actuator in the housing such that the first engagement end of the actuator rod abuts against the tooth and wherein the first engagement end is capable of sliding along the sliding surface of the tooth;
- providing a cartridge assembly having a cartridge housing and positioning a plunger head in the cartridge housing and providing an injection needle and extending the injection needle from the plunger head and placing the carriage assembly in the housing;
- mounting a stop wall in the housing interior and mounting a plunger stop block on the stop wall and the plunger stop block defines a block needle opening, and defining a central opening and a first actuator opening in the stop wall, and the first actuator rod extends through the first actuator opening;
- and,
- wherein when the actuator ring is pressed against a surface the first actuator rod engages the sliding surface of the tooth causing the release component and tooth to rotate such that as rotation of the release component continues the first and second release slots rotate into alignment with the first and second support arms and upon alignment the main spring is released, and the main spring forces on the plate to move the plate and the cartridge housing through the housing causing the plunger head to press against the plunger stop block such that a fluid in the cartridge housing flows out of the cartridge housing, through the injection needle, and out the injection needle.