Hypodermic jet injection kit

• US 20030040715A1
• Filed: 08/20/2002
• Published: 02/27/2003
• Est. Priority Date: 08/21/2001
• Status: Active Grant

• Current Assignee: D'Antonio Consultants International, Inc.
• Original Assignee: D'Antonio Consultants International, Inc.
• Inventors: Colvin, Richard O., DʼAntonio, Nicholas F., DʼAntonio, Linda F.
• Granted Patent: US 7,235,063 B2
• Time in Patent Office: Days
• US Class Current: 604/187
• CPC Class Codes: A61D 1/025 Vaccination appliances hypodermic syringes A61M
• CPC Class Codes: A61M 2005/005 Magazines with multiple ampoules directly inserted into an injection or infusion device, e.g. revolver-like magazines containing ampoules with or without needles
• CPC Class Codes: A61M 2209/086 Docking stations
• CPC Class Codes: A61M 5/001 Apparatus specially adapted for cleaning or sterilising syringes or needles
• CPC Class Codes: A61M 5/002 Packages specially adapted therefor, e.g. for syringes or needles, kits for diabetics needle protection, e.g. caps, A61M5/3202; for sharps A61B50/3001
• CPC Class Codes: A61M 5/1782 Devices aiding filling of syringes in situ combination of a vial and a syringe for transferring or mixing their contents A61J1/2096, filling of medical containers in general B65B3/003
• CPC Class Codes: A61M 5/2448 comprising means for injection of two or more media, e.g. by mixing
• CPC Class Codes: A61M 5/30 Syringes for injection by jet action, without needle, e.g. for use with replaceable ampoules or carpules

Abstract

A hypodermic injection system particularly for use in mass immunizations having a handpiece with a grasping mechanism for holding ampules filled with injectate, a plunger for driving into the ampule to discharge the injectate in an injection process, an injection spring mechanism for driving the plunger, a motor and/or manual mechanism for cocking the injection spring mechanism, and an ampule ejection mechanism for ejecting ampules after use under control of a release mechanism. Ampules can be loaded, used and ejected without contact by the user of the system or the patient being injected. Also disclosed are a filling station for filling ampules through their injection orifices, and an arming device for setting the injection spring. Ampules are disclosed having a piston which is drivable towards an orifice to discharge injectate through the orifice. Ampules are also disclosed having enlarged proximal portions for easy grasping by the grasping mechanism of the injector. Ampules are further disclosed with separators for mixing lyophilized medication and a diluent. Further disclosed are magazines for holding ampules for sequential use by the hypodermic injector. The disclosed system finds particular use as a mass immunization kit for making numerous injections in the field.

Claims

1. A hypodermic injector for injecting fluid from an ampule loaded in said injector from a plurality of ampules in sequence, each ampule having a sealed condition for containing injectate in a sealed container and an empty condition where the injectate was discharged from the ampule without the necessity of human contact with the ampule, said injector comprising:

a gasping mechanism having a grasping condition for grasping an ampule and holding the ampule to receive an injectate discharge force, and an open condition;

a plunger device movable from a set condition to a discharge condition for applying discharge force to an ampule in the sealed condition to eject injectate from the ampule to render the ampule in the empty condition;

a first biasing device having a cocked condition for storing a biasing force in said device and a released condition, said first biasing device discharging force to said plunger device to move said plunger device from the set condition to the discharge condition in response to the movement of said biasing device from the cocked condition to the release condition;

a first cocking mechanism for moving said first biasing device from the release condition to the cocked condition;

a release mechanism actuatable for releasing said biasing mechanism from the cocked condition to the released condition to effect the movement of said plunger device from the set condition;

an ejector mechanism for ejecting an empty ampule from said grasping mechanism in the open condition, said ejector mechanism including an ejector member movable from a set condition to an eject condition for engaging and ejecting an ampule from said injector, and a second biasing device releasable from a cocked condition to a release condition to drive said ejector member to eject the ampule; and

a second cocking mechanism for moving said second biasing device from 5 the released condition to the cocked condition.

2. A hypodermic injector according to claim 1 wherein said second cocking mechanism moves said second biasing device to the cocked condition in response to the loading of an ampule into said injector.

3. A hypodermic injector according to claim 1 wherein said ejector mechanism comprises:

a manually operable manual release member for discharging said second biasing device from the cocked condition.

4. A hypodermic injector according to claim 1 and further including a motor having a drive shaft operatively connected to said first cocking mechanism, said drive shaft being rotatable in one direction to cause said first cocking mechanism to assume the cocked position from the release position to move said biasing device from the release condition to the cocked condition, and automatically rotatable in a reverse direction to reset said drive shaft for the next operation to cause said first cocking mechanism to assume the cocked condition.

5. A hypodermic injector according to claim 1 wherein said grasping mechanism assumes the open condition when no ampule is grasped by said grasping mechanism, and wherein said grasping mechanism includes a disabling device for disabling said plunger device from moving from the set condition when no ampule is in said grasping mechanism and said grasping mechanism is in the open condition.

6. A hypodermic injector according to claim 1 and further including a motor having a drive shaft operatively connected to said first cocking mechanism, said drive shaft being rotatable to cause said first cocking mechanism to assume the cocked position from the release position to move said biasing device from the release condition to the cocked condition.

7. A hypodermic injector according to claim 6 wherein said hypodermic injector further includes a handpiece with a housing for containing said grasping mechanism, plunger device, biasing device, first cocking mechanism, release mechanism, ejector mechanism and second cocking mechanism, wherein said motor is remote from said handpiece, and wherein said injector further includes a coupling mechanism for operatively coupling said motor to said first cocking mechanism.

8. A hypodermic injector according to claim 6 wherein said hypodermic injector further includes a handpiece with a housing for containing said grasping mechanism, plunger device, biasing device, first cocking mechanism, release mechanism, ejector mechanism, second cocking mechanism and motor.

9. A hypodermic injector according to claim 1 wherein said grasping mechanism comprises:

gripper jaws having a closed position for releasably engaging an ampule inserted in said grasping mechanism and an open position;

a jaw expansion spring device having a set position for biasing said gripper jaws to the open position and a release position;

a jaw capture sleeve having a holding position for releasably holding said gripper jaws in the closed position and a release position for enabling said gripper jaws to move to the open position;

a jaw capture sleeve return spring releasable from a set position to a release position for biasing said jaw capture sleeve from the release position to the holding position when in the set position;

an ampule eject spring releasable from a set position to a release position to eject an ampule from said hypodermic injector; and

an ampule release mechanism for moving said jaw capture sleeve from the holding position to the release position and for releasing said ampule eject spring from the set position to the release position;

said jaw capture sleeve being movable from the release position to the holding position, said jaw expansion spring being movable from the release position to the set position, said jaw capture sleeve return spring being movable from the release position to the set position, and said ampule eject spring being movable from the release position to the set position, in response to the loading of an ampule into said gripper jaws.

10. A hypodermic injector according to claim 1 wherein the ampules have an outer wall with an interior chamber for containing the injectate, a proximal end and a distal end with an orifice in the distal end through which injectate can flow, the chamber extending between the distal end and the proximal end, and a piston movable from the proximal end towards the distal end to force injectate from the chamber through the orifice, wherein said injector further includes a motor having a drive shaft operatively connected to said first cocking mechanism, said drive shaft being rotatable in one direction to cause said first cocking mechanism to assume the cocked position from the release position, and said motor shaft being operatively connectable to the ampules and being rotatable in the reverse direction to draw the piston from the distal end of the ampule to the proximal end of the ampule to enable filling of the ampule with the injectate through the orifice.

11. A hypodermic injector according to claim 1 and further including a magazine for sequentially presenting an ampule to be grasped by the grasping mechanism from ampules held in sequence in a strip of ampules, said magazine comprising:

a housing having a holding region for holding a strip of ampules, a presenting region for making an ampule accessible to said grasping mechanism and walls for guiding a strip of ampules from said holding region in sequence to said presenting region;

a take-up spool for taking up portions of the ampule strip after ampules have been withdrawn from the strip by said grasping mechanism; and

a driving device for moving said take-up spool to receive the portions of the ampule strip after ampules have been withdrawn from the strip.

12. A hypodermic injector according to claim 11 wherein said housing comprises:

an access wall having access surfaces defining an opening to said presenting region wherein said grasping mechanism can grasp an ampule in said presenting region and withdraw the ampule from said magazine.

13. A hypodermic injector according to claim 11 wherein said walls define a curved, generally helical path for the ampule strip, wherein the ampule strip following the outermost part of said path locates the lead ampule in said presenting region to be grasped by said grasping mechanism, prior to the disposition of the ampule strip having had the ampule withdrawn therefrom on said take-up spool.

14. A hypodermic injector according to claim 13 wherein said magazine comprises:

a base portion having said walls extending therefrom, said walls further defining a compartment for holding said take-up spool; and

a cover portion having a funnel-shaped opening to said presenting area from which an ampule on the ampule strip extends from said presenting region to be grasped by said grasping mechanism.

15. A hypodermic injector according to claim 11 wherein said driving device is a negator spring.

16. A hypodermic injector according to claim 11 wherein said walls define at least one linear path in said housing for guiding the ampule strip towards said take-up spool, and wherein said presenting region is on said linear path adjacent to said take-up spool.

17. A hypodermic injector according to claim 16 wherein said walls define at least two parallel linear paths connected by a path interconnecting an adjacent end of said paths, wherein the ampule strip is movable along one linear path in one direction and along the adjacent path in the opposite direction, said linear paths terminating at said presenting region adjacent said take-up spool.

18. A hypodermic injector according to claim 17 wherein said housing comprises:

a base portion from which said walls extend, said base portion further having a take-up spool compartment for holding said take-up spool; and

a cover for said base portion, said cover having a funnel-shaped opening for receiving a portion of an ampule in said presenting region to provide access to said grasping mechanism to grasp the ampule.

19. A hypodermic injector according to claim 11 wherein said housing comprises an exterior wall having an opening to said presenting region for said grasping mechanism to grasp an ampule in said presenting region, and further comprising guiding walls for guiding said grasping mechanism to said opening to grasp an ampule.

20. A hypodermic injector according to claim 1 wherein said first biasing device is at least one spring having a biasing force sufficient to drive said plunger device with enough energy to eject injectate at jet velocity.

21. A hypodermic injector according to claim 20 wherein said at least one spring has a spring force of at least 60 pounds.

22. A hypodermic injector according to claim 21 wherein said at least one spring has a spring force of at least 80 pounds.

23. A hypodermic injector according to claim 21 wherein said at least one spring has a spring force of between 60 and 105 pounds.

24. An ampule for use with a hypodermic jet injector, said ampule comprising:

a body portion with a proximal end, a distal end and a longitudinal axis extending between said proximal end and said distal end, said body portion having a chamber having a relatively large opening in said proximal end and terminating before said distal end, and further having a relatively small orifice extending between the termination of said chamber and said distal end; and

a piston located in said chamber for moving from said proximal end towards said orifice to drive injectate between said piston and said orifice through said orifice.

25. An ampule according to claim 24 wherein said body portion is symmetrical about the longitudinal axis, and has a relatively wide portion near said proximal end and a relatively narrow portion near said distal end, said wide portion being graspable by a grasping mechanism of the jet injector.

26. An ampule according to claim 24 and further including a slidable spool located in said chamber between said piston and said proximal end, and a spring device associated with said spool locking said spool in said chamber against movement towards said proximal end;

said piston being slidable in said chamber from a position adjacent said orifice to said spool in response to the flow of injectate under pressure through said 5orifice; and

said spool forcing said piston towards said orifice by the high-speed impact of a plunger against said spool to force injectate through said orifice to effect an injection.

27. An ampule according to claim 24 wherein the hypodermic jet injector has a ram for pushing said piston from said proximal end towards said orifice to drive injectate through said orifice, said piston being frangible in response to receiving a sufficient amount of force from the ram, said piston being movable in response to the initial movement of the ram to drive injectate through said orifice, and said piston breaking in response to the further movement of the ram to render said ampule inoperative.

28. An ampule according to claim 24 and further including a perforator at the end of said orifice for penetrating the skin of a body being injected to control the injection depth and to reduce the force required to make the injection.

29. An ampule according to claim 28 and further including a disabling device substantially covering said perforator for disabling said ampule after an injection has been made using the ampule.

30. An ampule according to claim 29 wherein said disabling device is a collapsible cover for said perforator having a weakened wall which collapses upon the rendering of an injection to render said perforator “

inaccessible.”

31. An ampule according to claim 24 wherein said perforator is the thickness of skin of the person or animal to be injected at the place of injection, the animals include dogs, cats, pigs, cows, horses, elephants, chickens, roosters, geese, lobsters, goats, camels and sheep.

32. An ampule according to claim 31 wherein said perforator has a length of from 1.0 mm to 12.7 mm.

33. An ampule strip for feeding ampules to a hypodermic injector for effecting injections from injectate held in the ampules, said strip comprising:

a backing strip having a length for holding a plurality of ampules in a linear relationship and parallel to each other;

a plurality of ampules being generally symmetrical about respective longitudinal axes and located in a parallel relationship on said backing strip, the respective ampules each having a proximal end and a distal end with an orifice extending through the distal end, the distal ends of each of said ampules extending in the same direction; and

a loop belt extending along and attached to said backing strip, said loop belt having a sequence of loops for releasably holding said ampules on said backing strip with the proximal ends all facing one direction.

34. A magazine for holding ampules having a distal end and a proximal end, for use with a hypodermic injector, said magazine comprising:

a set of at least two segments which are connected together by a hinge device to enable the folding of said segments together, each segment including;

a rigid backing strip;

one of said hinge devices at at least one end of said segment for attachment to an adjacent segment; and

a loop belt extending along and attached to said backing strip, said loop belt having a sequence of loops for holding the ampules on said backing strip with the proximal ends of the ampules all facing in one direction, said loop belt being flexible at the intersection of adjacent segments to enable the folding of said adjacent segments;

wherein the hypodermic injector can tear ampules in turn from the backing strip and the loop belt.

35. A magazine according to claim 34 wherein the ampules have an enlarged cross-sectional area in the region adjacent said proximal end relative to the region adjacent said distal end, wherein said loop belt holds the ampules with the region adjacent said proximal end to extend from said loop belt to provide access to a hypodermic injector.

36. An ampule for a hypodermic injector, said ampule comprising:

a body portion having inside surfaces defining a chamber, said body portion having an orifice extending to said chamber at one end of the body portion defining a path for injectate during an injection;

a piston in said chamber extending between the inside surfaces of said body portion;

a portion of said chamber on one side of said piston for initially holding lyophilized medication;

a portion of said chamber on the other side of said piston for holding a diluent for the lyophilized medication; and

structure for enabling flow and mixture of the diluent with the lyophilized medication in response to movement of said piston to prepare injectate to be discharged from said ampule.

37. An ampule according to claim 36 wherein said structure comprises a one-way valve on said piston for opening when the piston moves in a direction away from said orifice, and closing in response to movement of said piston towards said orifice to effect an injection.

38. An ampule for a hypodermic injector, said ampule comprising:

a body portion having inside surfaces defining a chamber, said body portion having an orifice extending to said chamber at one end of said body portion for discharging injectate during an injection; and

a piston located in said chamber extending between said inside surfaces and defining a cavity between said piston and said orifice for receiving lyophilized medication;

said orifice being able to receive diluent under pressure for mixing with the lyophilized medication in said cavity to form an injectate; and

said piston being movable away from said orifice in response to the entry of diluent into said cavity to enlarge the size of said cavity.

39. An ampule assembly for a hypodermic injector, said ampule assembly comprising:

a body portion having inside surfaces defining a first chamber, said body portion having an orifice extending to said first chamber at one end of said body portion defining a path for injectate during an injection;

an ampule piston in said first chamber extending between the inside surfaces of said body portion defining an ampule cavity between said ampule piston and said orifice; and

an appendage attachable to said body portion over said orifice, said appendage including;

interior surfaces defining a second chamber;

a discharge opening for connection to said orifice in said body portion;

an appendage piston extending across an end of said second chamber; and

a frangible separator extending across said second chamber and located between said appendage piston and said discharge opening to define a first appendage cavity between said separation and said appendage piston, and a second appendage cavity between said separator and said discharge opening;

at least one of said second appendage cavity and said ampule cavity being a receptacle for lyophilized medication and said first appendage cavity being a receptacle for diluent, said frangible cavity rupturing to effect the mixing of the lyophilized medication and the diluent to form an injectate in response to the application of sufficient force to said appendage piston, said ampule piston being movable in response to the flow of at least one of diluent or injectate through said orifice to increase the size of said ampule cavity; and

said appendage being detachable from said ampule to clear said orifice, and said ampule piston being movable towards said orifice to inject injectate through said orifice.

40. An ampule assembly according to claim 39 wherein said ampule cavity is the receptacle for the lyophilized medication, and the first appendage cavity is the initial receptacle for the diluent.

41. An ampule assembly according to claim 39 wherein said first appendage cavity is the initial receptacle for the diluent and said second appendage cavity is the initial receptacle for lyophilized medication.

42. An ampule for a hypodermic injector, said ampule comprising:

a body portion having inside surfaces defining a chamber, said body portion having an orifice extending to said chamber at one end of said body portion for discharging injectate during an injection;

a piston located in said chamber extending between said inside surfaces; and

a frangible separator extending between said inside surfaces and located between said orifice and said piston to separate said chamber into one cavity for holding lyophilized medication and a second cavity for holding a diluent, said separator being ruptured in response to the movement of said piston into one of said cavity when filled with one of the lyophilized medication and the diluent to effect mixing of the lyophilized medication and the diluent for ejecting through said orifice.

43. One ampule according to claim 42 wherein said one cavity is between said orifice and said separator, and said second cavity is between said separator and said piston.

44. A magazine for mixing lyophilized medication and diluent in at least one ampule assembly, each assembly having an ampule with a body portion defining a first chamber having an inlet and outlet orifice at one end with a piston movable in said first chamber, said magazine comprising:

at least one collapsible storage container being connectable to the orifice, the container having collapsible walls defining a collapsible second chamber and a separator extending across the second chamber to separate the second chamber into one cavity for holding lyophilized medication and a second cavity for holding diluent; and

a force transfer member for operative connection to said at least one collapsible storage container for collapsing the collapsible walls of said at least one container in response to the application of a sufficient force to said force transfer member to effect the rupturing of the respective separators, the mixing of the respective lyophilized medication and diluent in the respective ampule assemblies, and to fill the respective ampules with the mixed lyophilized medication and diluent through the respective orifices.

45. An arming station for setting an injection spring in a hypodermic jet injector to make the injector ready for an injection from a fired condition to a ready condition, the hypodermic jet injector having a holding device for holding an ampule containing an injectate, apparatus for discharging the injectate upon the impact of a plunger at a predetermined end of the ampule, a plunger device for being driven into the predetermined end of the ampule to provide the impact to discharge the injectate, at least one spring having enough spring force upon the tensioning of the spring to a set condition to drive the plunger into the ampule to provide the impact to discharge the injectate and a holding device for holding the at least one spring in the ready condition, and a cocking member movable a predetermined amount to set the injection spring, said arming station comprising:

a rearming dock for holding a fired hypodermic jet injector in position to have the injector rearm to the ready condition;

a manual device for moving the cocking member by the predetermined amount to set the injection spring, said manual device including a manually movable gripping member for gripping the cocking member and moving it in response to the manual movement of the gripping member.

46. A rearming station according to claim 45 wherein the cocking member is a draw rod which must be pulled for a predetermined distance to set the injection spring, and said manual device includes a device for gripping the draw rod and a lever for moving said gripping device by the predetermined distance to set the injection spring.

47. A rearming station according to claim 45 and further including a pick-up cradle for holding a hypodermic injector having been rearmed to the ready condition pick-up for use as an injector.

48. A hypodermic injector system for making injections at a field site, said system comprising:

a hypodermic injector for making injections, said hypodermic injector comprising;

a grasping apparatus having a closed position for holding ampules containing injectate for subsequent discharge of injectate during an injection, and an open position for terminating the holding of an ampule;

a plunger for being driven into a held ampule to discharge injectate from the ampule;

an injection spring having a set condition and a released condition operatively connected to said plunger, said injection spring driving said plunger into the ampule when said injection spring is released from the set condition;

a spring cocking member for being movable from a rest position to a setting position for moving said spring from the released condition to the set condition;

a coupling for coupling an external energy source to said spring cocking member to move said member from the rest position to the setting position;

a trigger operatively connected to said injection spring for releasing said injection spring from the set condition to the released condition to render an injection;

an ampule ejection device for ejecting an ampule from said injector;

an ampule eject spring operatively connected to said ampule ejection device and having a set condition and a released condition, said ampule eject spring effecting the discharge of an ampules from said grasping apparatus when said grasping apparatus is in the open position upon the release of said ampule eject spring from the set condition to the released condition, the leading of an ampule into said grasping apparatus effecting the changing of said ampule eject spring from the released condition to the set condition; and

an ampule release mechanism for placing said grasping apparatus in the open position and for releasing said ampule eject spring from the set condition to cause said ampule ejection device to eject an ampule from said injector; and

a motor and battery module being selectively connected to said coupling for resetting said cocking member from the rest position to the setting position.

49. A hypodermic injection system according to claim 48 wherein said injection spring has sufficient spring force in the set condition to drive said plunger with enough force to eject injectate from the ampule at jet speed.

50. A hypodermic injection system according to claim 48 wherein the spring force of said injection spring is at least 60 pounds.

51. A hypodermic injection system according to claim 50 wherein the spring force of said injection spring is at least 80 pounds.

52. A hypodermic injection system according to claim 51 wherein the spring force of said injection spring is between 80 and 105 pounds.

53. A hypodermic injection system according to claim 48 and further including a motor module selectively connected to said coupling for resetting said cocking member from the rest position to the setting position, and a battery selectively coupled to said motor to energize the motor.

54. A hypodermic injection system according to claim 48 and further including a manual reload module for selectively connecting said reload module to said coupling for manually resetting said cocking member from the rest position to the setting position.

55. An ampule filling station for filling ampules with injectate, the ampules including a body portion with an interior chamber having one end of the chamber closed with an orifice extending through the closed end for admitting and discharging injectate, the ampules being arrangeable in a magazine with the one end being acceptable to a filling device, said filling station comprising:

a syringe for holding a reservoir of an injectate;

a piston in the syringe being movable in a direction to discharge injectate from said syringe;

a syringe operating member movable for actuating said piston to discharge injectate from the syringe; and

a holding device for holding the magazine to hold the ampules in position to receive injectate from said syringe in response to the operation of said syringe operating member.

56. An ampule filling station according to claim 55 wherein said syringe operating member is a lever movable to actuate said piston

57. An ampule filling station according to claim 56 wherein said lever is a manually operable lever.

58. A hypodermic jet injector for discharging injectate from ampules in sequence in an injection process, said injector comprising:

an ampule grasping mechanism for grasping an ampule prior to an injection;

a plunger for being driven into the ampule to discharge injectate from the ampule;

an injection spring releasable from a set position to drive said plunger into the ampule;

a ball screw assembly having a motor with a motor shaft, said motor shaft being selectively rotatable in forward and reverse directions, and a ball screw;

a power linkage operatively connected to said ball screw assembly and to said injection spring, said power linkage having a cocked position for releasing said injection spring from the set position, and a release position;

a firing trigger actuable for releasing said power linkage from the cocked position to the release position;

an ampule release system including an ampule release trigger, and an ampule release member for ejecting an ampule in response to actuation of said ampule release trigger;

a motor coupler mechanism connectable and disconnectable from said motor to stop operation of said motor;

a first switch being releasable to stop operation of said motor and being actuable to cause said motor to rotate in the forward direction to reset said power linkage from the release position to the set position and to put said injection spring in the set position;

a second switch actuable in response to the actuation of said ampule release trigger; and

a switch arm being movable in one direction in response to actuation of said firing trigger to release said first switch to stop operation of said motor, and said switch arm being movable in a reverse direction in response to actuation of said ampule release trigger to actuate said first and second switches to reset said power linkage and set said injection spring and to cause said motor to reverse direction, said ball screw moving in response to the reverse direction of said motor to disconnect said motor coupler mechanism from said motor to stop said motor.

59. A hypodermic jet injector for discharging injectate from ampules in sequence in an injection process, said injector comprising:

a handpiece;

an ampule grasping mechanism for grasping an ampule prior to an injection;

a plunger for being driven into the ampule to discharge injectate from the ampule;

an injection spring releasable from a set position to drive said plunger into the ampule;

a ball screw assembly having a motor with a motor shaft, said motor shaft being selectively rotatable in forward and reverse directions, and a ball screw;

a power linkage operatively connected to said ball screw assembly and to said injection spring, said power linkage having a cocked position for releasing said injection spring from the set position, and a release position;

a firing trigger actuable for releasing said power linkage from the cocked position to the release position;

a switch being releasable to stop operation of said motor and being actuable to cause said motor to rotate in the forward direction to reset said power linkage from the release position to the set position and to put said injection spring in the set position; and

a switch arm being movable in one direction in response to actuation of said firing trigger to release said switch to stop operation of said motor, and said switch arm thereafter being movable in a reverse direction to reset said ball screw assembly.