Retractable syringe with a closed barrel

Claim 2

A retractable syringe, comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft having a pair of spaced collars along its length for locking the shaft in the inserted position in the rearward end of the barrel, the rearward end of said barrel having a lip at the open end with a diameter slightly smaller than the diameter of the collars, said lip moving over one of said collars to be locked between the collars; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 3

A retractable syringe as claimed in claim 1 wherein, said one of said collars having a canted outer circular rim surface for camming said first collar through the lip at the rearward end of the barrel.

Claim 4

A retractable syringe as claimed in claim 2 wherein, said collars on said shaft have an outer circular dimension that is slightly smaller than the internal diameter of said barrel providing lateral stability of said shaft in movement in said barrel.

Claim 5

A retractable syringe as claimed in claim 1 wherein, means adjacent the rearward opening and on said piston that locks the piston and the grasped needle holder in the retracted position.

Claim 6

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft having a portion along its length that is comprised of a pair of aligned lath members spaced across the diameter of the cross section of said shaft, with the inner edge surfaces being spaced from the cross sectional center of said shaft, whereby said shaft may be broken by moving the rear end of said shaft in a direction normal to the alignment of said two members; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position, with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 7

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft having a portion along its length that is comprised of a pair of aligned lath members spaced across the diameter of the cross section of said shaft, with the inner edge surfaces being spaced from the cross sectional center of said shaft, whereby said shaft may be broken by moving the rear end of said shaft in a direction normal to the alignment of said two members; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position, with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 8

A retractable syringe as claimed in claim 5 wherein, said weakened section being adjacent to said piston.

Claim 9

A retractable syringe as claimed in claim 5 wherein, said pair of radially aligned lath section interconnecting the front end of said shaft with the rear surface of said piston.

Claim 10

A retractable syringe as claimed in claim 5 wherein, said pair of lath members being scored on the sides thereof.

Claim 11

A retractable syringe as claimed in claim 5 wherein, said barrel has adjacent said rearward opening an inward projecting member, and said piston has an outer surface for abutting against said inward member, blocking movement of said piston out the open end of said barrel.

Claim 12

A retractable syringe as claimed in claim 9 wherein, said inward projecting member comprising spaced dimples.

Claim 13

A retractable syringe as claimed in claim 10 wherein, said dimples having a given diameter therebetween, and said shaft having an outer rim adjacent the rearward end of the shaft with a diameter slightly smaller than said given diameter for laterally stabilizing said shaft in movement of said barrel.

Claim 14

A retractable syringe as claimed in claim 5 wherein, a sheath having a closed forward end and rear open end that fits over the forward end of the needle holder and needle, the rear open end has a shoulder that abuts the forward end of said barrel, whereby when said sheath is positioned over said needle and needle holder, forces applied to said sheath are exerted against the end of the barrel.

Claim 15

A retractable syringe as claimed in claim 5 wherein, said needle holder has a forward groove, an arcuate lock clip for fitting into said groove and abutting the front end surface of said barrel, whereby said lock clip positioned in said groove, prevents rearward movement of said needle holder.

Claim 16

A retractable syringe as claimed in claim 13 wherein, said lock clip having a "C" shape with a slightly larger circumference than half the circumference of said groove for being laterally snapped in said slot and being resiliently retained in position, and one end of said clip has a projection that may be actuated to remove said lock clip from said slot.

Claim 17

A retractable syringe as claimed in claim 5 wherein, said piston having a circumferential slot at its forward end, and the needle holder having fingers at its rearward end with inwardly directed ends for fitting into said slot, securing the needle holder to said piston.

Claim 18

A retractable syringe as claimed in claim 15 wherein, the forward end of said piston has a frusto-conical collar adjacent said slot, and said fingers comprising said radial sections that are cammable over said frusto-conical surface into latching engagement between the needle holder and the piston.

Claim 19

A retractable syringe as claimed in claim 16 wherein, said needle holder has an internal fluid passage that communicates with said needle.

Claim 20

A retractable syringe as claimed in claim 5 wherein, said shaft having a weakened section along its length for breaking said shaft.

Claim 21

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft comprising a plurality of longitudinal members joined at adjacent surfaces to provide a composite cross-section that extends in two dimensions, increasing lateral stability of the shaft; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 22

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft comprising a plurality of longitudinal members joined at adjacent surfaces to provide a composite cross-section that extends in two dimensions, increasing lateral stability of the shaft; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 23

A retractable syringe as claimed in claim 19 wherein, said members comprising laths joined together in a cross-sectional configuration with an outer radial diameter slightly less than the inner radial diameter of the barrel.

Claim 24

A retractable syringe as claimed in claim 20 wherein, said lath members are arranged in a cross sectional configuration that when in the barrel, the center space of said barrel is longitudinally open, for receiving the needle and needle holder when the broken end of said shaft is inserted into the open end of said barrel.

Claim 25

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having an outer rectangular shaped circumferential slot with an O-ring having a substantially rectangular cross-section and a rearward edge surface canted radially inward, said O-ring positioned in said slot fitting against the inner surface of said barrel for forming a movable seal; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 26

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having an outer rectangular shaped circumferential slot with an O-ring having a substantially rectangular cross-section and a rearward edge surface canted radially inward, said O-ring positioned in said slot fitting against the inner surface of said barrel for forming a movable seal; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 27

A retractable syringe as claimed in claim 22 wherein, said O-ring positioned in the outer radial slot of said piston having a split outer radial surface with a radially inward space in said outer surface, providing a pair of separate outer resilient circumferential contacts between the O-ring and the inner surface of said barrel.

Claim 28

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, said needle holder having a rearward circumferential slot, the forward end of said piston having fingers, each said finger having an inward projection for fitting into said circumferential slot for securing said piston to said needle holder, said needle holder having an internal fluid passageway communicating with said needle, said fluid passageway having an end on said circumferential slot; a second passageway comprising a single chamber with an opening in said slot; the ends of said fingers having arcuate surfaces for providing open spaces in said slot; said shaft having indication means for orienting said arcuate surfaces on said fingers to expose and not cover said passageway; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 29

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, said needle holder having a rearward circumferential slot, the forward end of said piston having fingers, each said finger having an inward projection for fitting into said circumferential slot for securing said piston to said needle holder, said needle holder having an internal fluid passageway communicating with said needle, said fluid passageway having an end on said circumferential slot; a second passageway comprising a single chamber with an opening in said slot; the ends of said fingers having arcuate surfaces for providing open spaces in said slot; said shaft having indication means for orienting said arcuate surfaces on said fingers to expose and not cover said passageway; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 30

A retractable syringe as claimed in claim 24 wherein, said rearward end of said needle holder has a frusto-conical collar adjacent said slot, and said fingers comprising radial sections that are cammable over said frusto-conical surface into latching engagement between the piston and said needle holder.

Claim 31

A retractable syringe as claimed in claim 24 wherein, said slot and said inward projection having coacting camming surfaces to release for rearward movement of said needle holder.

Claim 32

A retractable syringe as claimed in claim 24 wherein, said inward projection and said needle holder slot having an interacting key and slot that locks the needle holder against rotating movement in the forward end of the barrel.

Claim 33

A retractable syringe as claimed in claim 27 wherein, the rear surface of said needle holder has an internal recess for being accessed by a tool that rotatably positions said holder in the opening of said barrel.

Claim 34

A retractable syringe as claimed in claim 27 wherein, the rear surface of said needle holder has a radially centered nut surface for coacting with a wrench to rotatably orient said needle holder in the open forward end of said barrel.

Claim 35

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, the forward end of said piston having fingers with inwardly directed ends, a needle holder and needle fitting into the forward end of the barrel in a resiliently contractible connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said piston having a grasping device that pulls the needle holder out of said resiliently contractible connection to the enclosed position in the barrel, said needle holder has an outer slot, a second circumferential slot rearward of said outer slot, an O-ring positioned in said second slot for radially sealing the inner barrel opening adjacent the forward end, and a third rearward circumferential slot for engaging said fingers therein, and the forward end of said barrel has an inward, resilient, circumferential lip that resiliently fits into said outer slot, resiliently holding the needle holder in the forward end of the barrel.

Claim 36

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, the forward end of said piston having fingers with inwardly directed ends, a needle holder and needle fitting into the forward end of the barrel in a resiliently contractible connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said piston having a grasping device that pulls the needle holder out of said resiliently contractible connection to the enclosed position in the barrel, said needle holder has an outer slot, a second circumferential slot rearward of said outer slot, an O-ring positioned in said second slot for radially sealing the inner barrel opening adjacent the forward end, and a third rearward circumferential slot for engaging said fingers therein, and the forward end of said barrel has an inward, resilient, circumferential lip that resiliently fits into said outer slot, resiliently holding the needle holder in the forward end of the barrel.

Claim 37

A retractable syringe as claimed in claim 30 wherein, the rearward end of said needle holder has a frusto-conical surface adjacent said third slot, and said fingers comprising radial sections that are cammable over frusto-conical surface into latching engagement between the piston and said needle holder.

Claim 38

A retractable syringe as claimed in claim 31 wherein, said lip and said slot having a radially directed key slot and key that locks the needle holder against rotating movement in the forward end of the barrel.

Claim 39

A retractable syringe as claimed in claim 32 wherein, the rear surface of said needle holder has means for engaging a tool that rotatably positions said needle holder in the opening of said barrel, engaging said key in said key slot.

Claim 40

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft having an outer ring portion midway its length with a diameter slightly smaller than the inner diameter of said barrel, for stabilizing said shaft in movement in said barrel, a needle holder and needle fitting into the forward end of the barrel in a resiliently contractible connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said needle having a grasping device that grasps the end of the piston, the piston being movable in said barrel for pulling the needle holder out of said resilient contractible connection to an enclosed position within the barrel, and said rear opening in said barrel having inward projections for restricting pulling said plunger and piston out of said barrel.

Claim 41

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said shaft having an outer ring portion midway its length with a diameter slightly smaller than the inner diameter of said barrel, for stabilizing said shaft in movement in said barrel, a needle holder and needle fitting into the forward end of the barrel in a resiliently contractible connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said needle having a grasping device that grasps the end of the piston, the piston being movable in said barrel for pulling the needle holder out of said resilient contractible connection to an enclosed position within the barrel, and said rear opening in said barrel having inward projections for restricting pulling said plunger and piston out of said barrel.

Claim 42

A retractable syringe as claimed in claim 34 wherein, said needle holder has a forward groove, an arcuate lock clip having a C-shape for fitting into said groove and abutting the front end surface of said barrel, whereby said lock clip positioned in said groove, prevents rearward movement of said needle holder.

Claim 43

A retractable syringe as claimed in claim 34 wherein, a sheath having a closed forward end and a rear open end that fits over the forward end of the needle holder and needle, and the rear open end has a shoulder that abuts the forward end of said barrel, whereby when said sheath is positioned over said needle and needle holder, forces applied to the sheath are exerted against the end of the barrel.

Claim 44

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position; said piston having a circumferential slot, and said rearward open end of said barrel having an V-shaped inward ring that fits into said circumferential slot, retaining said piston in a locked retractable position in said open end; said circumferential slot in said piston having a pair of adjacent outer side edges that fit against each side of the inward ring providing a fluid seal therebetween.

Claim 45

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position; said piston having a circumferential slot, and said rearward open end of said barrel having an V-shaped inward ring that fits into said circumferential slot, retaining said piston in a locked retractable position in said open end; said circumferential slot in said piston having a pair of adjacent outer side edges that fit against each side of the inward ring providing a fluid seal therebetween.

Claim 46

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having a circumferential slot, and said rearward open end of said barrel having an inward projection; and the radial outer surface of the rearward end of said piston having a larger diameter than the inner diameter of the projection in the rear open end of said barrel, for preventing said inner rim surface from fitting into the rear radial slot; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 47

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having a circumferential slot, and said rearward open end of said barrel having an inward projection; and the radial outer surface of the rearward end of said piston having a larger diameter than the inner diameter of the projection in the rear open end of said barrel, for preventing said inner rim surface from fitting into the rear radial slot; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 48

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open, said needle holder having a first circumferential slot; said forward opening of said barrel having a circumferential lip, said lip fitting in said slot for releasably securing said needle holder in a releasable position; said needle holder having a second circumferential slot rearward of said first circumferential slot, and an O-ring positioned in said slot for resiliently sealing the inner barrel opening adjacent the forward end, said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 49

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open, said needle holder having a first circumferential slot; said forward opening of said barrel having a circumferential lip, said lip fitting in said slot for releasably securing said needle holder in a releasable position; said needle holder having a second circumferential slot rearward of said first circumferential slot, and an O-ring positioned in said slot for resiliently sealing the inner barrel opening adjacent the forward end, said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 50

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said forward end of said syringe barrel having inward projections; a needle holder and needle, said needle holder having a slot, said inward projections of said syringe barrel fitting into said slot in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 51

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said forward end of said syringe barrel having inward projections; a needle holder and needle, said needle holder having a slot, said inward projections of said syringe barrel fitting into said slot in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 52

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having an outer circumferential slot with an O-ring positioned in said slot fitting against the inner surface of said barrel for forming a movable seal, said barrel having metering marks along the length thereof that coact with one of the edge surfaces of said outer radial space of said O-ring for providing metering indication of fluid in said barrel; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 53

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, said piston having an outer circumferential slot with an O-ring positioned in said slot fitting against the inner surface of said barrel for forming a movable seal, said barrel having metering marks along the length thereof that coact with one of the edge surfaces of said outer radial space of said O-ring for providing metering indication of fluid in said barrel; a needle holder and needle fitting into the forward end of the barrel in a releasable connection that releases the needle holder for movement toward the rearward end and to a retracted position where the barrel encloses the needle holder and needle, and the forward end of the barrel is open; said piston and needle holder having engaging means for securing the piston to the needle holder; said piston being movable in said barrel for pulling the needle holder out of said releasable connection to the retracted position; and said shaft being breakable along its length with the broken end of the shaft inserted into the forward end of the barrel holding the needle holder and needle in the retracted position.

Claim 54

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, a needle holder and needle fitting into the forward end of the barrel in a connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said piston and needle holder having engaging means that interconnects the piston and the needle holder, whereby pulling the piston towards said rearward end pulls the needle holder out of said resiliently contractible connection to the enclosed barrel, said piston has an outer circular slot with an O-ring positioned in said slot, said O-ring having a split outer radial surface with at least a pair of spaced wiping surfaces separated by an inward space therebetween, and said O-ring fitting against the inner surface of said barrel forming a movable seal.

Claim 55

A retractable syringe comprising: a syringe barrel with open forward and rearward ends and a piston and shaft in the barrel with one end of the shaft extending out the rearward open end, a needle holder and needle fitting into the forward end of the barrel in a connection that resiliently holds the needle holder from movement toward the rearward end to a position where the barrel encloses the needle holder and needle, said piston and needle holder having engaging means that interconnects the piston and the needle holder, whereby pulling the piston towards said rearward end pulls the needle holder out of said resiliently contractible connection to the enclosed barrel, said piston has an outer circular slot with an O-ring positioned in said slot, said O-ring having a split outer radial surface with at least a pair of spaced wiping surfaces separated by an inward space therebetween, and said O-ring fitting against the inner surface of said barrel forming a movable seal.