A reciprocating syringe that can be used in connection with existing syringe barrels and fittings. Some embodiments comprise a frame, adapted to retain two existing syringe barrels. The frame can accommodate fittings on one or both barrels. The invention also provides a plunger complex, comprising two plungers, each adapted for use with one of the syringe barrels. The two plungers are coupled such that pushing of each plunger into its barrel causes the other plunger to pull outwards relative to its barrel. The two plungers can be coupled by a flexible line attached to one plunger, routed from the plunger out of the corresponding barrel into the other barrel, and attached to the other plunger. The invention contemplates various frame configurations to accommodate desired line and pulley performance characteristics. Other embodiments comprise a frame adapted to retain an existing syringe barrel, and an auxiliary actuator mounted with the frame. Such an actuator can provide a syringe-like plunger operation, or can comprise other manipulable structures. The auxiliary actuator can be coupled to a plunger adapted for use with the syringe barrel, such that pushing the plunger into the barrel causes the actuator to move in a reversible manner, and moving the actuator in the reverse manner causes the plunger to pull outwards relative to its barrel. The invention also comprises various materials, methods of making, geometries and arrangements of parts, and accommodation of various specific existing syringe designs and applications.
