Some embodiments of a medical infusion pump system include a pump device having a cap device (130) that mates with a pump housing (110) to retain a medicine cartridge (120) therein. In addition to retaining the medicine cartridge in the pump housing, the cap device may perform a number of preparatory functions or safety functions. In addition or in the alternative, some embodiments of the pump device may include a drive system that advances a piston rod to dispense medicine to the patient in a safe and energy efficient manner.
