A reciprocating syringe that can be used in connection with existing syringebarrels and fittings. Some embodiments comprise a frame, adapted to retain twoexisting syringe barrels. The frame can accommodate fittings on one or bothbarrels. The invention also provides a plunger complex, comprising twoplungers, each adapted for use with one of the syringe barrels. The twoplungers are coupled such that pushing of each plunger into its barrel causesthe other plunger to pull outwards relative to its barrel. The two plungerscan be coupled by a flexible line attached to one plunger, routed from theplunger out of the corresponding barrel into the other barrel, and attached tothe other plunger. The invention contemplates various frame configurations toaccommodate desired line and pulley performance characteristics. Otherembodiments comprise a frame adapted to retain an existing syringe barrel, andan auxiliary actuator mounted with the frame. Such an actuator can provide asyringe-like plunger operation, or can comprise other manipulable structures.The auxiliary actuator can be coupled to a plunger adapted for use with thesyringe barrel, such that pushing the plunger into the barrel causes theactuator to move in a reversible manner, and moving the actuator in thereverse manner causes the plunger to pull outwards relative to its barrel. Theinvention also comprises various materials, methods of making, geometries andarrangements of parts, and accommodation of various specific existing syringedesigns and applications.
