US2764980A

US2764980A - Continuous injection machine

Info

Publication number: US2764980A
Application number: US280947A
Authority: US
Inventors: Smith William Ralph
Original assignee: Upjohn Co
Current assignee: Pharmacia and Upjohn Co
Priority date: 1952-04-07
Filing date: 1952-04-07
Publication date: 1956-10-02
Anticipated expiration: 1973-10-02

Description

Oct. 2, 1956 w. R. SMITH CONTINUOUS INJECTION MACHINE Filed April 7, 1952 4 Sheets-Sheet 1 Oct. 2, 1956 w. R. SMITH 2,764,980

CONTINUOUS INJECTION MACHINE Filed April 7. 1952 4 Sheets-Sheet 2 Oct. 2, 1956 w. R. SMITH 2,764,980

CONTINUOUS INJECTION MACH INE )NVENTOR.

Filed April 7, 1952 W. R. SMITH CONTINUOUS INJECTION MACHINE 4 Sheets-Sheet 4 q T'TORNE' Y United States Patent CONTINUOUS INJECTION MACHINE William Ralph Smith, Kalamazoo, Mich., assignor to The Upjohn Company, Kalamazoo, Mich., a corporation of Michigan Application April 7, 1952, Serial No. 280,947

13 Claims. (Cl. 128-218) This invention relates to a. continuous injection machine and particularly to a type thereof providing a common drive for a plurality of syringe plungers and wherein any one of said plungers may be disconnected from the common drive by a simple manipulation and without disturbing the continuity or accuracy of the driving of the other plungers.

In continuous injection machines whereby small quantitles of liquid, as ten cubic centimeters, are to be injected into a laboratory test animal, as a white rat, over a somewhat. extended period of time, as twenty-four hours, it is necessary that very small quantities of liquid be injected per hour and that such quantities of liquid be injected at an accurate rate. Further, inasmuch as in different tests the test animals are subjected to injections for different periods of time, it is desirable to provide a. device by which the driving mechanism for the plungers of the different syringes may be connected and disconnected as desired without disturbing the continuity of, or accuracy of, movement of the other plungers of the device and by which the several drivingmechanisms may be readily positioned as desired with respect tothe several plungers in order that syringes may be started with different quantities of liquid therein with respect to each other.

Still further, in view of the long periods of time over which such apparatus will be expected to operate, itis desirable that simple means be provided by which, when a given plunger reaches the end of its stroke, the driving mechanism may be disconnected from said plunger'so that.

continuing operation of said driving mechanism will not break the syringe of which such plunger is a part,

and such disconnection of the driving mechanism will be confined to said particular plunger and will noteifect the operation of other plungers being driven by said driving mechanisms.

Accordingly, a principal object of the invention is to provide a device for operating multiple syringes wherein the mechanism operating any one syringe can be readily disconnected from the remainder of the device without affecting the speed or accuracy of operation of the rest of the device.

A further object of the invention is to provide a device, as aforesaid, wherein the disconnecting of the means operating any one syringe may be manually effectedby an operator and without the use of tools of any kind.

A further object of the invention is to provide a device, as aforesaid, wherein the disconnecting of the means operating a selected syringe may be effected quickly and easily and without endangering the operators hands or fingers.

A further object of the invention is to provide a device, as aforesaid, which is simple and economical to construct.

A further object of the invention is to provide a device, as aforesaid, which will be easy to operate and. to maintain.

A further object of the invention is to provide a device,

as aforesaid, in which upon the completion of'a fullstroke by the plunger of. any syringe of the group, the mechanism operating said plunger may be readily and automatically disconnectedv from the power source of the apparatus Figure 4 is a section taken on the line IVIV of Figure 2.

Figure 5 is a section taken onthe line VV of Figure 2 and. rotated counterclockwise.

Figure 6 is a section taken on the line VI-VI of Figure 2 androtated 90 counterclockwise.

Figure 7 is asection taken on the line VIIVil of Figure 2.

Figure 8 is a top view of the gear train.

Construction in general In general, my improved construction contemplates providing a continuously rotatable shaft extending parallel to, and substantially co-extensive with, means for holding a plurality of syringes of adesired type andsize, the axes of said syringes being each positionedperpendicularly to the axis of said shaft. A rack is provided in substantial alignment Witheach of said syringes and said rack is positioned perpendicularly to the axis of said shaft. Means are providedv supporting said rack for reciprocation toward and away from the syringe holding device. Gears are provided on said shaft and are slidable axially thereof for engaging and disengaging,

said racks at the will'ofan operator, by whichsaidracks may be, as desired, caused to move toward said syringe holding devices or freed from such movement.

Construction in detail- In describing the preferred embodiment of the invention here selected for illustrative purposes, the following terminology will be employed for purposes of convenience in reference but with no thought of limitation. The term forward, and derivatives and synonyms thereof, will refer to directions or motions in the same direction as the syringe plunger moves when in'aninjecting stroke, which is'rightwardly as the machine appears in any of Figures 1, 2 and 3, and the term rearward, and derivatives and synonyms thereof, will refer toim-otionsor directions in an opposite direction. The terms rightward and leftward, and derivativesthereof, will ref'e'"- to the. respective sides of. the machine when viewedasappearing in Figure 4.

Referring now to the drawingsin detail, there is pro vided a. base member 1: which is here shown as a casting,-

but may be. fabricated, and comprises a. web 2 and downwardly extending flanges 3; 4 an'd'S. Side members- 6 and 7 are'afiixed to the. downwardly extending flanges Sand 5, respectively, and extend upwardly aidistance above the web 2 to support certainhereinafter described parts above saidweb. The motor supporting flange S is provided at the rearward end of thebase member land it, like the other downwardly extending flanges may be either integral or fabricated. Further downwardly. ex-

tending, flanges 9. and 11 may. be addedalso if deSired to provide further rigidity and-stability for the struct-ure;

Theforward endof said base member 1 isprovided Patented Oct. 2,. 1956 with a raised platform 12 for the support of syringe holding devices as hereinafter appearing in further detail.

A constant speed motor, or other constant speed prime mover 13 is supported in any convenient manner upon the motor supporting flange 8, as best appearing in Figure 3. Its output shaft 14 operates through a coupling 15 to drive the pinion 16 (Figure 8) and through it and the gear 16a to drive a worm 17. The shafts supporting said pinion, gear and worm are supported upon a gear frame 18 which in turn is supported in any convenient manner from the web 2 of said base member 1. Said worm 17 drives a gear 19 and from it is driven a worm 21 which drives the gear 22 (Figure 4). Said gear then drives the upstanding shaft 23 (Figures 4 and 7) for purposes appearing hereinafter.

It will be apparent that the gear box thus described is substantially conventional and may be replaced by any other desired means for driving the upstanding shaft 23 at a relatively slow but accurately controllable rate of speed.

Syringe holding stations areprovided by a plurality of syringe receptacles 24 (Figures 2 and 3) which are arranged along the raised platform 12 and are affixed thereto by a plurality of bolts 26 (Figure 1) each provided with a knurled head 27 for finger operation.

Suitable straps

28 and 29 are affixed at each of their respective ends onto the syringe receptacles 24, by any convenient means such as cap screws and function to hold the syringes in snug engagement with the syringe receptacles. The positions of the syringes 31a, 31b, 31c and 31d are shown in broken lines in Figures 1, 2 and 3.

Turning now to the syringe driving mechanism, a center fixture 32 (Figure 4), is supported upon the web 2 of the base member 1 and it is provided with a suitable opening for the reception of the center bearing 33 therein.

End bearings

34 and 35 are supported by the

side members

6 and 7, respectively, in coaxial alignment with the said center bearing 33. The drive shaft 36 extends through said three bearings and is rotatably supported thereby. Said drive shaft has a gear 37 mounted thereon for engagement with a worm 38 (Figure 7) which worm is driven by a shaft 39 from the upstanding shaft 23. Said shaft 39 is supported by a suitable bearing 41 within the base of the center fixture 32. The gear 37 is preferably received within a suitable recess 42 (Figure 4) within the center fixture 32 and said recess is closed by

end plates

43 and 44 both of which are preferably provided with suitable oil seals as shown. The

end bearings

34 and 35 are conveniently held in place by

retainer plates

45 and 46, respectively.

Syringe d riving gears 47 and 48 (Figures 2 and 4) are respectively aligned with and disposed. rearwardly of the syringes 31a and 31b. Said gears are each provided with hubs having knurled

surfaces

49 and 51. Said gears and their hubs are each freely rotatable upon and axially slidable with respect to the drive shaft 36. Each of said hubs have

openings

52 and 53 on their mutually opposed sides into which are received the pilots 54 and 55, respectively, of the driving

collars

56 and 57. Each of said driving collars are keyed to the drive shaft 36 in a conventional manner but the key groove 59 is sufliciently elongated to permit substantial axial movement of said collars. A coil spring 61 resiliently urges said driving collars and the gears respectively associated with each of said driving collars in mutually opposite directions and movement thereof in response to the urging of said spring is limited by the

stop collars

62 and 63. Connection between each driving collar and its respectively associated gear hub is provided by shear pins 64 and 66.

Gears

67 and 68 are aligned with and disposed rearwardly of the syringes 31c and 31d, respectively, and are mounted and driven on and from said drive shaft 36 in the same manner as above described in detail for the syringe driving gears 47 and 48.

A pair of rollers 69 and 71 (Figures 1 and 2) are posi- 4 tioned for rotation in the same plane their axes being parallel with each other and defining a plane parallel with the rearwardly projected axis of the syringe 31a. The roller 71 is rotatably mounted near the rearward end of the side member 6 (Figure 5) by the bearing 72, the pivot bolt 73 and the spacer 74. The roller 69 is similarly mounted near the forward end of the side member 6. A drive frame 76 is comprised of a pair of

rails

77 and 78 and a pair of stiles 79 and 81 which are affixed to said rails in any convenient manner and hold same spaced apart such a distance that they will cooperate closely with, while being supported by, the

rollers

69 and 71 as best illustrated in Figure 5. The opposed edges of said rails are preferably grooved for receiving the peripheral edges of said rollers snugly therewithin. The forward stile 79 is preferably wider than the width of said rails and it supports a contact member 82 on its forward side for contacting the rearward surface of the syringe plunger. The rack 83 is positioned for engagement with the syringe driving gear 47, as best appearing in Figures 2 and 4, and is supported on the rail 78 and on the forward stile 79 The

rollers

84 and 86 are rotatably mounted upon the center fixture 32 in a manner similar to the mounting of the

rollers

69 and 71. A pair of

rails

87 and 88 are disposed parallel to each other and engage opposite sides of said rollers (Figure 6) for horizontal reciprocation in the same manner as the

rails

77 and 78. The stiles 89 and 91 connect the ends of said rails and support the contact member 92. The rack 93 is supported on the rail 88 and on the stile 91. Said rack engages the syringe driving gear 48 for driving the drive frame in the same manner that the syringe driving gear 47 drives the drive frame 76. The mounting of the roller 86 is the same as the mounting of the roller 84.

The drive frames 94 and 96 are mounted by rollers onto the side member 7 and the center fixture 32, respecttvely, in the same manner as the

drive frame members

76 and 85 and they operate to move the syringes 31d and 310, respectively, upon actuation thereof through the

racks

97 and 98 by the

gears

68 and 67 upon rotation of the drive shaft 36.

Operation The operation has been generally indicated throughout the preceding description but to avoid any possibility of mlsunderstanding the operation will be summarized briefly.

The apparatus is made ready for operation by placing a plurality of syringes 31a, 31b, 31c and 31d within the syringe receptacles 24 and fastening the several holding straps in place. The syringe driving gear 47 is drawn rightwardly for disconnecting it from the rack 83 by an operator grasping the knurled surface 49 and the drive frame 76 is then moved backwardly a distance permitting the plunger of the syringe to move backwardly to the point at which it is desired to have the syringe commence operation. Thus, the syringe plunger may be retracted any distance desired. When the starting point is thus determined, the syringe driving gear 47 is permitted to be returned by the coil spring 61 "leftwardly (Figure 4) into engagement with the rack 83. Corresponding operatlons are performed with respect to the

gears

48, 67 and 68, their associated drive frames and the syringe plungers to be operated thereby. It will be recognized that each of the syringe plungers may thus be adjusted for its starting point independently of each of the other syringe plungers inasmuch as there will be no relationship be tween the several plungers as they are being driven. With the several driving gears in engagement with their respective racks, the motor 13 may be started and the drive shaft 36 will be rotated through the gear train mounted below the web 2, the shaft 39, the worm 38 and the gear 37. As drive shaft 36 rotates it will rotate the

several gears

47, 48, 67 and 68 and etfect the movement of the several drive frames respectively connected therewith through the several racks. Thus, each syringe plunger will be moved at a precisely predetermined, very slow, speed. If the

gears

47, 48, 67 and 68. are all the same size, said syringe plungers will all move at the same speed, or said syringe plungers may be caused to move at different speeds with respect to each other by utilizing

gears

47, 48, 67 and 68 of different sizes and adjusting the positions of the racks appropriately.

In the event it is desired to terminate the driving of any one syringe, or to return a given drive frame from a forward position to any selected rearward position, for example the syringe 31b, the drive gear connected therewith, here the gear 48, will be disconnected from the rack and the drive frame moved back to whatever extent is desired'. This is convenient when the operation of one syringe is completed and another one is to be put mto position, or in the event that a particularly long syringe may be used in one selected position such that two or more strokes of the drive frame associated therewith may be required to complete the stroke of the syrlnge. This will in no way effect the driving of any of the other drive frames.

In the event that any of the syringes, as syringe 31a, completes its stroke prior to the completion of the strokes of the other syringes and the operator fails to shut off, or d sconnect the drive gear associated therewith, the shear pm, here the shear pin 66 (Figure 4), will break, thus disconnecting the drive shaft 36 from the syringe driving gear 47 but the rest of the machine will continue without interruption or variation in speed. The strength of the given shear pins is, of course, so selected that it will break before the syringe driven thereby breaks.

Thus, it will be seen that this apparatus, while maintaining the high degree of accuracy and steadiness required in devices of this type is nevertheless capable of extreme flexibility in operation and extreme adaptability to a variety of requirements.

Further, it will be seen that any one or more of the drive frames may be returned by the operator to a startingposition in a matter of seconds entirely independently of'the operation of the rest of the machine and, particularly, without requiring that the machine or any part thereof be. operated in a reverse direction.

Accordingly, it will be understood that a device meeting the objects and, purposes above set forth has been herewith disclosed and described.

Other modifications may be made from the details of the device her selected for illustrative purposes but it will be recognized that such variations will normally be within the scope of the hereinafter appended claims excepting. as. such claims by their own express terms limit otherwise.

Iclaim:

1. In a continuous injection machine, the combination comprising: a base; means onsaid base for supporting 'a syringe; a shaft rotatably supported on said base and positioned substantially perpendicularly to the axis of said syringe; reciprocable means. supported on said base and positioned for hearing against the plunger of said syringe; means including an axially slidable member normally connected between said shaft and said reciprocable means for movingsaid reciprocable means toward said syringe supporting means upon rotation of said shaft in a selecteddi-rection, said axially slidable member being manually movable to a position opening the connection be tween same and. said reciprocable means and resilient means normally holding said axially slidable member in connected relationship with said reciprocable means.

2. In a continuous injection machine, the combination comprising: a base; means on said base for supporting a plurality of "syringes. in a. single row, said syringes being positioned parallel with each other and the plungers thereof extending in the same direction; a continuously rotating shaft rotatably supported on said base and positioned substantially perpendicularly to th axes of said syringes and disposed at all times entirely beyond the free said plungers; disconnectable means rotatable with said.

shaft for normally connecting said shaft and each of said reciprocable means independently for moving each of said, reciprocable means toward said syringe supportingmeans 'at selected rates upon rotation of said shaft in a selected direction.

3. In a continuous injection machine, the combination comprising: a base; a plurality of syringe supporting stations arranged on said base to support said syringes in a single row with the axes of their respective plungers substantially parallel with each other, said plungers extending in the samerdirection; a drive shaft disposed substantially perpendicularly to the axes of said syringe plungers. and disposed at all times entirely beyond the axial ends of all said plungers; means rotatably supporting said drive shaft upon said base; a prime mover and means including. reduction gears connecting said prime mover to said drive shaft for rotating same continuously; a plurality of reciprocable means each one thereof being arranged re spectively substantially in axial alignment with a said plunger for reciprocation in a direction parallel with the axes of said plungers, and each reciprocable means. including a rack; a plurality of gears rotatable with said shaft, said gears being engageable respectively with said racks and each of said gears being axially slidable on said shaft; resilient meansv normally holding said gears respectively in engagement with said racks, for driving said racks at selected rates with respect to each other.

4. In a continuous injection machine, the combination comprising: a base; a pair of syringe supporting stations arranged on said base to support a pair of syringes adjacent each other with the axes of their respective plungers substantially parallel with each other, said plungers extending in the same direction; a drive shaft disposed substantially perpendicularly to the :axes of said syringe plungers; means rotatably supporting said drive shaft upon said base; a prime mover and means including 'reduction gears connecting said prime mover to said drive shaft for rotating same continuously; a pair of reciprocable means arranged respectively substantially in. axial alignment with saidplungers for reciprocation in a direction parallel with the axes of. said plungers, and each reciprocable means including a rack; a pair of gears axially slidably arrangedon said shaft for rotation by said shaft, said gears-being normally in engagement respectively with said racks for driving same at selected rates with respect to each other; resilient mean-s urging said'gears in axially opposite directions and stop collar means associated with each of said gears limiting-the response of said gears to said urging at such a point that said gears will normally engage respective ones of said racks.

5. In acontinuous injection machine, the combination comprising: a base; a pair of syringe supporting stations arranged on said base to support a pair of syringes adjacent each other with the axes of their respectiveplungers substantially parallel with each other; a drive shaft disposed substantially perpendicularly to the axes of said syringe plungers; means rotatably supporting said drive shaft upon said base; a prime mover and means including reduction gears connecting said prime mover to said drive shaft for rotating same continuously; a pair of reciprocable means arranged respectively substantially in axial alignment with said plungers for reciprocation in a direction parallel with the axes of said plungers, and each reciprocable means including a rack; a pair of gears axially slidably androtatably supported on said shaft and spaced from each other; a driving collar associated with each of said gears, said driving collars being rotatable with said shaft and slidable axially with respect to said shaft; a coil spring surrounding said shaft and urging said drivingcollars away from eachother and against said respective gears; and a shearable pin connecting each-of said driving collars and the gear associated therewith; and stop means associated with each of said gears limiting the response of said gears to said urging at such a point that said gears will normally engage respective ones of said racks, for driving same at selected rates.

6. In a continuous injection machine, the combination comprising: a base; a syringe supporting station on said base; a drive shaft disposed substantially perpendicularly to the axis of the plunger of said syringe and entirely beyond the free end thereof; means rotatably supporting said drive shaft upon said base; a prime mover and means including reduction gears connecting said prime mover to said drive shaft; a pair of similar rollers whose radii lie substantially within a single plane and having parallel axes defining a plane parallel with the axis of said syringe and each supported on said base frame for independent rotation with respect to each other; a drive frame including a pair of supporting rails one rail being above the other, the upper of said rails resting on at least one of said rollers; means mounted on said drive frame for engaging the plunger of said syringe, and a rack parallel with and secured to the side of said drive frame; an axially slidable gear rotatably supported on said drive shaft and normally engaging said rack, and means for selectively connecting said gear to said drive shaft for rotation therewith while permitting axial movement of said gear with respect to said shaft for disengaging said gear from said rack. 7. In a continuous injection machine, the combination comprising: a base; a pair of syringe supporting stations arranged on said base so that syringes positioned in said stations will be supported adjacent each other with the axes of their respective plungers substantially parallel with respect to each other; a drive shaft disposed substantially perpendicularly to the axes of said syringe plungers; means rotatably supporting said drive shaft upon said base; a prime mover and means including reduction gears connecting said prime mover to said drive shaft for driving same continuously; a pair of drive means, each including a pair of rollers whose radii lie substantially within a single plane and having parallel axes defining a plane parallel with the axes of said syringes, all of said rollers being supported on said base frame for independent rotation with respect to each other; a pair of drive frames each including a pair of supporting rails, one rail being above the other, the upper of said rails resting on at least one of said pair of rollers; means mounted on each said drive frame for engaging a respective plunger and a rack parallel with and secured to the side of said drive frame; a pair of gears axially slidably arranged on said shaft for rotation by said shaft and being normally in engagement with each of said respective racks; resilient means urging said gears in axially opposite directions, and stop means associated with each of said gears limiting the response of said gears to said urging at such a point that said gears will normally engage respective ones of said racks, for driving same at selected rates.

8. In a continuous injection machine, the combination comprising: a base; a pair of syringe supporting stations arranged on said base so that syringes positioned in said stations will be supported adjacent each other with the axes of their respective plungers substantially parallel with respect to each other; a drive shaft disposed substantially perpendicularly to the axes of said syringe plungers; means rotatably supporting said drive shaft upon said base; a prime mover and means including reduction gears connecting said prime mover to said drive shaft for driving same continuously; a pair of drive means, each including a pair of rollers whose radii lie substantially within a single plane and having parallel axes defining a plane parallel with a plane defined by the axes of said syringes, all of said rollers being supported on said base for independent rotation with respect to each other; a pair of drive frames each including a pair of supporting rails, one rail being above the other, the upper of said rails resting on at least one of said pair of rollers; means mounted on each said drive frame for engaging a respective plunger and a rack parallel with and secured to said drive frame; a pair of gears axially slidably and rotatably supported on and by said shaft and spaced from each other; a driving collar associated with each of said gears, said driving collars being rotatable with said shaft and slidable axially with respect to said shaft; a coil spring surrounding said shaft and urging said driving collars away from each other and against said respective gears; and a shearable pin connecting each of said driving collars and the gear associated therewith; and stop collar means associated with each of said gears limiting the response of said gears to said urging at such a point that said gears will normally en gage respective ones of said racks, for driving same at selected rates.

9. In a continuous injection machine, the combination comprising: a base; means on said base for supporting a syringe; a shaft rotatably supported on said base and positioned substantially perpendicularly to the axis of said syringe; reciprocable means supported on said base and positioned for bearing against the plunger of said syringe; means including an axially slidable member on said shaft for rotation with said shaft and normally connecting said shaft and said reciprocable means for moving said syringe supporting means upon rotation of said shaft in a selected direction, said axially slidable member being manually movable to a position opening the connection between same and said reciprocable means and resilient means normally holding said axially slidable member in connected relationship with said reciprocable means.

10. In a continuous injection machine, the combination comprising: a base; means on said base for supporting a syringe; a shaft rotatably supported on said base and positioned substantially perpendicularly to the axis of said syringe; reciprocable means supported on said base and positioned for bearing against the plunger of said syringe; means including an axially slidable member on said shaft for rotation with said shaft and normally connecting said shaft and said reciprocable means for moving said reciprocable means toward said syringe supporting means upon rotation of said shaft in a selected direction, said shaft and said means including an axially slidable member being disposed at all times entirely beyond the axial end of said plunger, said axially slidable member being manually movable to a position opening the connection between same and said reciprocable means and resilient means normally holding said axially slidable member in connected relationship with said reciprocable means.

11. In a continuous injection machine, the combination comprising: a base; means on said base for supporting a syringe; a shaft rotatably supported on said base and positioned substantially perpendicularly to the axis of said syringe; reciprocable means supported on said base and positioned at all times entirely beyond the axial end of the plunger of said syringe for bearing against said plunger; means including an axially slidable member on said shaft and normally connecting said shaft and said reciprocable means for moving said reciprocable means toward said syringe supporting means upon rotation of said shaft in a selected direction, said axially slidable member being manually movable to a position opening the connection between same and said reciprocable means and resilient means normally holding said axially slidable member in connected relationship with said reciprocable means.

12. A continuous injection machine including the combination comprising: a base; means on said base for supporting a pair of syringes positioned substantially adjacent each other, said syringes being positioned parallel with each other and the plungers thereof extending in the same direction; a shaft rotatably supported on said base and positioned substantially perpendicularly to the axes of said syringes and disposed at all times entirely beyond the free ends of all said plungers; a plurality of reciprocable means independently supported on said base and each of said means positioned for bearing respectively against one of said plungers; disconnectable means rotatable with said shaft for normally connecting said shaft and each of said reciprocable means independently for moving each of said reciprocable means toward said syringe supporting means at selected rates upon rotation of said shaft in a selected direction.

13. In a continuous injection machine, the combination comprising: a base; a syringe supporting station on said base; a drive shaft disposed substantially perpendicularly to the axis of the plunger of said syringe and entirely beyond the free end thereof; means rotatably supporting said drive shaft upon said base; a prime mover and means including reduction gears connecting said prime mover to said drive shaft; a pair of similar rollers whose radii lie substantially within a single plane and having parallel axes defining a plane parallel with the axis of said syringe and each supported on said base frame for independent rotation with respect to each other; a drive frame including a pair of supporting rails one rail being above the other, the upper of said rails resting on at least one of said rollers; means mounted on said drive frame for engaging the plunger of said syringe; means including an axially slidable member normally connected between said shaft and said drive frame for moving said reciprocable means toward said syringe supporting station upon rotation of said shaft in a selected direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,457,977 Cookson Jan. 4, 1949 2,498,672 Glass Feb. 28, 1950 2,502,676 Smith Apr. 4, 1950 2,574,263 Hinds Nov. 6, 1951 FOREIGN PATENTS 28,796 Great Britain Dec. 13, 1913 143,084 Great Britain May 20, 1920