US3816033A - Multi-channel pump - Google Patents

Abstract

A multi-channel pump and more particularly a peristaltic pump having a single casing carrying drive means, the casing including a portion for receiving from 1 to 10 or more individual pump units which are arranged in side by side relation, each of the pump units being independently operable by the drive means on the casing; each of the pump units being removably mounted on the casing for independent use or removal; each of the pump units carrying flexible tubing for peristaltic action by the pump unit; the drive means on the casing comprising a pair of spaced drive units operating at respectively different speeds, the pump units being adapted to be selectively arranged in either of two positions on the casing so as to operatively engage one of the drive units for operation at one speed or to operatively engage the other of the drive units for operation at the other speed.

Description

United States Patent 1191 Fried et al.

1451 June 11, 1974 MULTI-CHANNEL PUMP [75] inventors: George Fried, Stamford, Conn.;

Oscar Botero, Woodside, NY.

[73] Assignee: Greiner Scientific Corporation, New

York, NY.

[22] Filed: Nov. 21, 1972 [21] Appl. No.: 308,418

[52] US. Cl 417/429, 417/475, 417/477 [51 Int. Cl.F04b 23/04,F04b 43/08 [58] Field of Search 417/429, 475, 477, 476

[56] References Cited UNITED STATES PATENTS 1,123,712 l/l9l5 Driver 417/429 2,376,917 5/1945 Hiltz 417/429 X 2,935,028 5/1960 Ferrari et al 1 417/477 X 3,124,270 3/1964 Cornell 417/429 X 3,298,238 l/l967 Lea 417/429 X 3,384,080 5/1968 Muller 417/477 X 3,507,585 4/1970 Mercer 417/475 3,723,030 3/1973 Gelfand 417/477 X Primary Examiner-William L. Freeh Assistant Examiner-Richard E. Gluck [5 7] ABSTRACT A multi-channel pump and more particularly a peristaltic pump having a single casing carrying drive means, the casing including a portion for receiving from 1 to 10 or more individual pump units which are arranged in side by side relation, each of the pump units being independently operable by the drive means on the casing; each of the pump units being removably mounted on the casing for independent use or removal; each of the pump units carrying flexible tubing for peristaltic action by the pump unit; the drive means on the casing comprising a pair of spaced drive units operating at respectively different speeds, the pump units being adapted to be selectively arranged in either of two positions on the casing so as to operatively engage one of the drive units for operation at one speed or to operatively engage the other of the drive units for operation at the other speed.

16 Claims, 7 Drawing Figures PATENTEBJUR 11 m4 3.816133331m 1 or 3 FIGJ W .mmasiiiiliW .imm W PAIENTEBJH 11 mm 38 16L033 SHEEI 2 OF 3 mun.

PATENTEDJUN 1 1 m4 3816L033 sum an; a

102 43 FIG-7 162 MULTI-CHANNEL PUMP BACKGROUND OF THE INVENTION Conventional peristaltic pumps are primarily of the single channel type, for pumping a single flow of liquid. If multiple flows of liquid or gases are required, a plurality of pumps each carrying its own drive motor, must be used. This entails substantial pump costs.

More recently, it has been proposed, to provide pumps having a plurality of channels associated with a single drive motor. However, the number of channels is fixed in such pumps and if the requirement is for more channels than the fixed channel capacity of such pumps, then two or more pumps will be needed, again increasing overall pump costs.

Recent applications of peristaltic pumps requires substantial numbers of channels for simultaneous pumping. Thus, in ecology tests large and varying numbers of reagent flow may be required and appropriate pumping means must be provided. This normally entails the use of two or more complete pump units, each having its own motor drive. Since the cost of the motor drive is a substantial part of the overall pump cost, the investment in pumps can be substantial.

Further, with known multi-channel pumps, the rate of flow is uniform for each channel. To have channels of different flow rates, separate pumps must be used, each pump having a desired flow rate. Here again, the pumps are inflexible and the separate pumps required represent large capital investment.

Accordingly, an object of this invention is to provide an improved multi-channel peristaltic pump which has a single motor drive but is arranged to accommodate any given number of individual pump units, each of the units being arranged for operation from the single motor drive; the units being quickly and easily operatively associated or disassociated with the single motor drive.

Another object of this invention is to provide a pump of the character described, wherein the motor drive is located at one end of a casing having an open top portion, individual pump units being adapted to be removably arranged in any desired number in side by side relation in the open top portion of the casing, the motor drive including driving gear means and each pump unit including driven gear means for meshing with the driving gear means by merely locating the units in the open top portion of the casing.

A further object of the invention is to provide a pump of the character described, wherein the individual pump units may be releasably locked on the casing for operation and readily unlocked to allow for removal of the selected pump units from the casing; or for positioning the pump units on the casing in an inoperative position thereof.

Still another object of the invention is to provide a pump of the character described, wherein the motor drive includes a pair of elongated drive gears arranged to rotate at respectively different speeds, each pump unit having driven gear means for meshing with one of the elongated gears in one position of the pump unit on the casing, or meshing with the other of the elongated gear means in another position of the pump unit on the casing, thereby providing variations on pump flow rates as well as any desired number of pumping channels.

Still another object of this invention is to provide improved individual peristaltic pumping units for use in a multi-channel pump having a casing and a single motor drive mounted thereon, such units including a peristaltic roller plate mounted between a pair of closely spaced plate members, together with a backing member removably disposed between the plate members and in opposed relation to the roller plate for receiving tubing therebetween; the roller plate having peripheral driven portions adapted to project below the lower edges of the plate members for driven engagement with the motor drive.

Yet another object of this invention is to provide individual pump assemblies of the character described which include latching means for locking engagement with the casing with which the units are associated to retain the units in selected operative or inoperative relationship to the casing.

Still a further object of this invention is to provide a multi-channel peristaltic pump having a single motor drive for operating a varied number of individual pump units; the individual pump units being removably mounted on a casing portion of the pump, thereby providing a high degree of flexibility in pumping varied flows of reagents or the like, as required; and further, such pump units having alternative positions on the casing portion of the pump to provide alternative pumping rates to thereby provide further flexibility in the operation of the pump as a whole.

Yet a further object of this invention is to provide a multi-channel peristaltic pump of the character described, which is of simple construction; which has but a single motor drive for a varied number of individual pumping units; the pumping units being of a construction and a mode of association with the motor drive as to make the mounting, removal, or interchange of the pumping units quick and easy; and resulting in a moderate cost measured in terms of the substantial and varied capacities of pumping units.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a multi-channel pump embodying the invention;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a transverse sectional view thereof showing the arrangement of driving gears;

FIG. 4 is a side elevational view of a single pumping unit, with parts broken away and parts in section;

FIG. 5 is a transverse view taken along the line 5-5 of FIG. 2, with parts in section; showing an individual pump unit mounted on a casing and in an inoperative condition;

FIG. 6 is a partial elevational view, similar to that of FIG. 5, showing the individual pump unit disposed in one position on the casing for operation at one speed;

and.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The instant invention is directed essentially to a multi-channel pump, Le. a pump made up of a plurality of individual units, with each unit adapted to pump a different fluid reagent or the like. Further, such pump comprises a single operating motor having drive means by which one or more pump units are driven simultaneously; and each pump unit being quickly engaged with or disengaged from the drive means.

Further, the drive means of the pump may comprise a pair of drive members rotating at respectively different speeds; the individual pump units being adapted to be disposed in one position on the casing for operation from one of the pair of drive members, or an alternative position on the casing for operation from the other of the pair of drive members.

Thus, as shown in FIGS. 1, 2, a multi-channel peristaltic pump embodying the invention, is generally indicated at 10. The same comprises a base B including at one end thereof an enclosed motor casing generally indicated at C and an open top cradle portion A extending from one side of motor casing C for mounting scribed. The casing C comprises abottom wall 11, up-

standingside walls 12, atop wall 13 andend walls 14, 15. Suitable speed control means, not shown, is located within casing C and in circuit with motor M. Thecontrol knob 16 ontop wall 13 regulates the speed control means. An on-and-off switch and a reversing switch, not shown, are also disposed within casing C and suitably -connected in circuit with motor M. Thecontrol knobs 17, 18 ontop wall 13, respectively operate said on-and-off, and reversing switches.

The opentop cradle portion 10A comprises abottom wall 11A,side wall portions 20, 21.Side wall portions 20A, 21A of angular cross section extend aboveside wall portions 20, 21 and terminate in outwardly extendingflange portions 22, 23. The outer edge offlange portions 22, 23 are formed with longitudinally extendingbead portions 24, 25 for the purpose hereinafter appearingThecradle portion 10A further includes anend wall 26.

The open space incradle 10A, betweenwalls 15 and 26 is adapted to accommodate one or more individual pump units, generally indicated at 27 and of a flat configuration. Such units are later described in detail. Any given number ofpump units 27 may be arranged incradle 10A, in side by side relation and operated by motor M.

To this end, theoutput shaft 28 of motor M has agear 28A fixed thereto for meshing with a similar size drive gear 29. ln turn, gear 29 meshes with alarger idler gear 30 on astub shaft 30A, which in turn meshes with adrive gear 31 of similar size. Driving means extend fromdrive gears 29, 31 in the form of a pair ofelongated gear members 33, 34 respectively having reducedend portions 29A, 31A fixed togears 29, 31, saidgear members 33, 34 having longitudinally extendinggear teeth 33A, 34A respectively. Theelongated gear members 33, 34 extend longitudinally incradle portion 10Aadjacent bottom wall 11A thereof with their axes in a common horizontal plane.

Thegear members 33, 34 are journalled at their opposite ends by way of reducedend portions 29A, 31A in suitable bearings, not shown, onwalls 15, 26. The comparative size ofgears 29, 31 is such that gear 29 will operate at a relatively high speed, whereasgear 31 will operate at a relatively low speed; such differential speeds being also respectively transmitted togear members 33, 34.

Each of theflat pump units 27 is adapted to receive a single tubing T, or a pair of tubings T, T for suitable operation in a peristaltic manner and thus pump a given reagent or other liquid or gases to the output side of such tubings.

Thus, apump unit 27 comprises a pair of similarthin metal plates 40, 41.Plate 40 comprises acentral portion 42 of generally rectangular shape with oppositely disposed, laterally projectingwing portions 43 defined by an outervertical edge 44,top edge 45,bottom edge 46. Thecentral portion 42 is further defined by inset dependingvertical edge portions 47 which extend from the inner ends ofbottom edge 46.Portion 42 is further defined bybottom edge portions 48 extending toward each other and joined by a centrally disposedarcuate edge portion 49.

Thetop edge 50 ofplate portion 42 terminates at its opposite ends inhooked portions 51 extending toward each other and defined in part byvertical edge portions 52 which merge at their lower ends with edges 45.

The elements forming a peristaltic pump structure are disposed betweenplates 40, 41. Thus, acircular roller plate 55 is mounted betweenplates 40, 41; saidplate 55 having ahub portion 56 for mounting ashaft 57 carried in abushing 58 fixed inplate portions 42. Theplate 55 is stiffened by integralradial ribs 59 projecting from one side thereof. A series of molded nylon or otherplastic rollers 60 are rotatably mounted onstuds 61 fixed at one end thereof to peripheral portions ofplate 55 on one side thereof. The periphery ofplate 55 is formed withgear teeth 62 for selectively engagingteeth 33A ofgear member 33 orteeth 34A ofgear member 34, whenunits 27 are mounted incradle 10A; the lower portions of saidteeth 62 projecting belowedge 49 ofplates 41, 42.

A protectivethin shield 63 of molded plastic encloses A the upper portions ofteeth 62 onplate 55.Shield 63 comprises an upper,annular skirt portion 64 of greater radial dimension than that of a lowerannular skirt portion 64.Shield portion 64 has arim portion 64A which overliesteeth 62, FIG. 4. Theshield 63 lies against the inner surface ofroller plate 55, with inner annular edge thereof disposed between the inner edges ofrollers 60 and the opposed surface ofroller plate 55.

Combined spacer means and guide means for tubings T, or T, T" is located betweenplates 40, 41. To this end a pair of similar, moldedplastic spacer members 65, 66 are disposed betweenplates 40, 41. The spacer member includes aportion 67 formed with aconcave edge 68 for receivingrim portion 64A ofshield 63; abottom edge 69 coincident withedge 48 ofplate 41, and aright angle edge 70 coincident withedges 45, 52 ofplate 41.

Projecting outwardly of the inner surface ofspacer member 65 is a T shapedportion 71 having avertical portion 72 abuttingplates 40, 41 and ahorizontal portion 73 extending to plate 40 and having an inner end overlying theportion 64 ofshield 63. Threaded bores 74, 75 are adapted to receiveassembly screws 76 for securingplates 40, 41 to saidspacer members 65, 66.

Means is provided for providing a backing member for coaction withrollers 60 onroller plate 55 to act on the pump tubings T, T and T. To this end there is provided a flat moldedplastic member 77 of yoke shape withopposite end portions 78 interconnected by a central raisedbackup portion 79, having aconcave bottom edge 80. Thebacking portion 79 is formed with a longitudinal slot 81 for receiving therein astem member 82 having reversely threaded, spacedopposite end portions 83, 84. Thestem member 82 is retained between the walls defining slot 81 by acollar 85 overlying said stem member and agrommet 86 holding saidcollar 85 in place.

A pair ofcylindrical locking units 87 having threadedopenings 88 extending transversely thereof, are threaded on threadedportions 83, 84 respectively ofstem member 82. Aknob 89 fixed to one end ofstem member 82 allows for rotation ofstem member 82 in either direction to move lockingmembers 87 toward or away from each other. The inward movement of lockingunits 87 is limited byvertical edge portions 89 ofcentral portion 79. Locating pins 90 are mounted onend portions 78, projecting from one surface thereof.

It is understood that withbackup member 77 separated fromplates 40, 41; the tubings T, or T, T" are disposed with their central portions overlying therollers 60 and their opposite end portions overlyinghorizontal portions 73 ofspacer members 65, 66. Thebackup member 77 may then be mounted between the upper portions ofplates 40, 41 and theconcave edge 80 thereof is properly located with respect to the opposedrollers 60, by the locating pins 90 which abutvertical edges 52 ofplates 40, 41.

The lockingmembers 87, being in intially retracted positions onstem member 82, readily clear thehooked portions 51 of saidplates 40, 41. By rotatingstem member 82 throughknob 89, in the proper direction, lockingmembers 87 are outwardly displaced to abut the hookedportions 51 ofplates 40, 41 to securely position backup means 77 in proper relation to therollers 60 onroller plate 55, with the tubings T, or T, T" therebetween.

Means is provided for retaining the tubings T, T or T" against longitudinal shift when thepump unit 27 is in operation. To this end, horizontalouter end portions 91 ofbackup member 77 are formed with vertically extending threadedopenings 92 to receive threaded pins 93. Friction shoes 94 are connected to the lower ends ofpins 93 for relative movement, withvertical guide portions 95 on said shoes received inappropriate guide slots 96 formed inportions 78. Rotatable knobs 97 fixed topins 93 immediately aboveshoes 94, allow for adjusted vertical movement of said shoes 94. Friction strips 98 on the bottom ofshoes 94 andfriction strips 98A onhorizontal portion 73 ofspacer members 65, 66, which are in opposed relation to friction strips 98, afford means for engaging the tubing portions therebetween to prevent slippage thereof.

Selectedpump units 27 may be mounted in the eradle A, in side by side relation, whereby theteeth 62 ofroller plates 55 will mesh with theteeth 33A ofdrive gear 33 or withteeth 34A ofdrive gear 34, as will be explained in detail.

Means is provided for releasably locking saidpump units 27 oncradle 10A. To this end, moldedplastic latch members 100 are pivotally mounted betweenwing portions 43 ofplates 40, 41.Latch members 100 are of rectangular tab shape with outwardly projectingears 101 at the upper end thereof for reception inopenings 102 inplate portions 43 ofplates 40, 41 with O rings 104 onears 101 to allow said latches to be pivoted to desired angular positions. The major portion of said latch members depend belowedge 46 ofplate portions 43. Thelatch members 100 are formed on their inner surfaces with transversely extending, vertically spacedrecesses 105, 106.

For locking saidpump units 27 in operative engagement withgear members 33 or 34; theunits 27 are positioned incradle 10A so thatlatch members 100 are pivoted to allowupper recesses 105 to engagebead edges 24, 25 ofcradle flanges 22, 23 as shown in FIGS. 6, 7.

If one or more of thepump units 27 is to be disengaged from operative connection to gearmembers 33 or 34, yet left incradle 10A; theunits 27 are so positioned relative to cradle 10A so that the lower latch recesses 106 receivebead edges 24, 25, thereby locking saidunits 27 oncradle 10A, withgear teeth 62 in spaced relation to gearteeth 33A, 34A, ofgear members 33, 34; as shown in FIG. 5.

It will be apparent thatlatch members 100 may be easily and quickly pivoted to either lock or unlock any ofpump units 27 in relation to cradle 10A, to thereby facilitate mounting, removing or interchanging any number ofpump units 27, as dictated by the pumping pattern desired.

Inasmuch asgear members 33, 34 respectively operate at different speeds, the rotational axis of gearedroller plate 55 is so located onplates 40, 41, as to dipose the same in offset relation to the center of the spacing betweengear members 33, 34 when thepump unit 27 is located oncradle 10A. It follows thatpump units 27 may take alternate positions oncradle 10A. In one case,teeth 62 ofroller plate 55 engage theteeth 33A ofgear member 33, as shown in FIG. 6; while upon turning theunit 27 through an angle of theunit 27 will be so positioned as to bring itsgear teeth 62 in meshing relation with thegear teeth 34A ofgear member 34, as shown in FIG. 7.

The tubing T may be of conventional diameters and wall thicknesses, as known in the peristaltic pump art. Either a single tubing T may be associated withpump units 27, or in the case of very small diameter tubings, a pair of such tubings t and T" may be used in asingle pump unit 27; see FIG. 1 and FIG. 2.

Knobs 16, 17 and 18 are manipulated to control motor speed; to reverse the motor and to stop and start the operation of the apparatus.

It will be apparent that with the pumping apparatus of the instant invention, a single motor drive may operate a varied number of pumping units to provide different pumping patterns, depending on the number of units used; the number of tubings involved; and the selected positions of the pump units on the cradle. Thus, the cost of providing a substantial range of pumping patterns is kept at a minimum with the use of a single motor drive.

What is claimed is:

1. A multi-channel pump apparatus comprising base means, motor means mounted on said base means, plural pump units adapted to be selectively mounted on said base means, an elongated rotatable drive means mounted on said base means, said rotatable drive means being coupled to said motor means and adapted to drive said pump units, means for removably mounting each of said pump units on said base means, each of said pump units including fluid carrying tubing means extending into said units, means within each pump unit for progressively compressing said tubing means during operation, rotatable driven means formed on the outer periphery of each of said pump units and adapted to engage said elongated rotatable drive means at selected positions along the length thereof to be driven thereby, said progressive compressing means mounted on said rotatable driven means, means for disengageably mounting each of said rotatable driven means of said pump units to said pump unit drive means for individual and simultaneous operation.

2. Pump apparatus as inclaim 1 wherein each of said pump units comprises a flat pump assembly, said assemblies being adapted to be selectively arranged in side by relation on selected portions of said base means for disengageable connection of each said operating means with said rotatable drive means.

3. Pump apparatus as in claim 2, wherein said drive means comprises an elongated gear member and each said driven means comprises gear means for meshing with said elongated gear member at selected positions along the length thereof in accordance with the position of the pump unit and its associated gear means relative to said base means.

4. Pump apparatus as in claim 2, and further including interengageable means on each of said pump assemblies and said base means for releasably locking said assemblies to said base means.

5. Pump apparatus as in claim 2, and further including latch means for selectively releasably locking said pump units to said base means in one position in which said drive means is in disengaged relation to said driven means, or in another position in which said drive means is in engaged relation to said driven means.

6. Pump apparatus as in claim 2 wherein said drive means comprises a pair of elongated gear members, means for rotating each of said pair of elongated gear members at respectively different speeds and said driven means comprises gear means, means for selectively positioning said pump assemblies on said base means, whereby in one of said positions, said gear means engages one of said pair of gear members for operation at one speed and in another of said positions said gear means engages the other of said pair of gear members for operation at another speed.

7. Pump apparatus as in claim 6 wherein said elongated gear members are disposed in laterally spaced relation to each other, the axis of said gear means being in laterally offset relation to the center of the lateral spacing of said pair of elongated gear members, whereby each of said pump assemblies may be selectively disposed in one position on said base means whereby said gear means theroof meshes with one of said pair of elongated gear members or in another position on said base means whereby said gear means thereof meshes with the other of said pair of elongated gear members.

8. Pump apparatus as in claim 3, wherein said base means comprises a pair of longitudinally extending side walls providing an open top, and'a pair of end walls connecting said side walls, said motor means being disposed outwardly of one of said end walls, said elongated gear member extending longitudinally between said base side walls, said side walls including longitudi nally extending flange portions extending from the upper edges thereof, each of said pump units including laterally related, shoulder portions for seating on said base flange portions to locate the lower peripheral edge portion of said driven gear means between said base walls for engagement with said elongated gear member.

9. A pump apparatus as inclaim 1 wherein said each pump unit comprises a pair of opposed, spaced plate members, spacer means between said plate members, a roller plate carrying roller members extending from one side of said roller plate and along the periphery thereof, said roller plate being rotatably mounted between said spaced plate members.

10. A pump as in claim 9 wherein said driven means comprises peripheral gear means on said roller plate.

11. A pump unit as in claim 9, and further including movable latch means mounted between said spaced plate members to releasably lock said pump unit to said base support means.

12. A pump unit as in claim 9 and further including movable latch means mounted on said pump units for selectively releasably locking said pump units to said base means in one position in which said drive means is in disengaged relation to said driven means, or in another position in which said drive means is in engaged relation to said driven means.

13. A pump unit as in claim 9, and further including a backing member disposed between said plate members, in opposed relation to said roller members, said roller plate including driven means thereon for engaging with the drive means on said base means when said pump unit is associated with said base means.

14. A pump unit as inclaim 13 wherein flexible tubing is adapted to be disposed between said backing member and the roller members on said roller plate, and adjustable friction means mounted on said spacer means for frictionally holding said tubing against shift relative to said backing means.

15. A pump unit as inclaim 10 wherein said roller plate is disposed adjacent said spacer means, and further including shield means for the gear means on said roller plate for protecting said tubing against wear.

16. A pump unit as inclaim 13, and further including coacting means on said backing member and said plate members for removably mounting said backing member between said plate members.

Claims (16)

1. A multi-channel pump apparatus comprising base means, motor means mounted on said base means, plural pump units adapted to be selectively mounted on said base means, an elongated rotatable drive means mounted on said base means, said rotatable drive means being coupled to said motor means and adapted to drive said pump units, means for removably mounting each of said pump units on said base means, each of said pump units including fluid carrying tubing means extending into said units, means within each pump unit for progressively compressing said tubing means during operation, rotatable driven means formed on the outer periphery of each of said pump units and adapted to engage said elongated rotatable drive means at selected positions along the length thereof to be driven thereby, said progressive compressing means mounted on said rotatable driven means, means for disengageably mounting each of said rotatable driven means of said pump units to said pump unit drive means for individual and simultaneous operation.

2. Pump apparatus as in claim 1 wherein each of said pump units comprises a flat pump assembly, said assemblies being adapted to be selectively arranged in side by relation on selected portions of said base means for disengageable connection of each said operating means with said rotatable drive means.

3. Pump apparatus as in claim 2, wherein said drive means comprises an elongated gear member and each said driven means comprises gear means for meshing with said elongated gear member at selected positions along the length thereof in accordance with the position of the pump unit and its associated gear means relative to said base means.

4. Pump apparatus as in claim 2, and further including interengageable means on each of said pump assemblies and said base means for releasably locking said assemblies to said base means.

5. Pump apparatus as in claim 2, and further including latch means for selectively releasably locking said pump units to said base means in one position in which said drive means is in disengaged relation to said driven means, or in another position in which said drive means is in engaged relation to said driven means.

6. Pump apparatus as in claim 2 wherein said drive means comprises a pair of elongated gear members, means for rotating each of said pair of elongated gear members at respectively different speeds and said driven means comprises gear means, means for selectively positioning said pump assemblies on said base means, whereby in one of said positions, said gear means engages one of said pair of gear members for operation at one speed and in another of said positions said gear means engages the other of said pair of gear members for operation at another speed.

7. Pump apparatus as in claim 6 wherein said elongated gear members are diSposed in laterally spaced relation to each other, the axis of said gear means being in laterally offset relation to the center of the lateral spacing of said pair of elongated gear members, whereby each of said pump assemblies may be selectively disposed in one position on said base means whereby said gear means theroof meshes with one of said pair of elongated gear members or in another position on said base means whereby said gear means thereof meshes with the other of said pair of elongated gear members.

8. Pump apparatus as in claim 3, wherein said base means comprises a pair of longitudinally extending side walls providing an open top, and a pair of end walls connecting said side walls, said motor means being disposed outwardly of one of said end walls, said elongated gear member extending longitudinally between said base side walls, said side walls including longitudinally extending flange portions extending from the upper edges thereof, each of said pump units including laterally related, shoulder portions for seating on said base flange portions to locate the lower peripheral edge portion of said driven gear means between said base walls for engagement with said elongated gear member.

9. A pump apparatus as in claim 1 wherein said each pump unit comprises a pair of opposed, spaced plate members, spacer means between said plate members, a roller plate carrying roller members extending from one side of said roller plate and along the periphery thereof, said roller plate being rotatably mounted between said spaced plate members.

10. A pump as in claim 9 wherein said driven means comprises peripheral gear means on said roller plate.

11. A pump unit as in claim 9, and further including movable latch means mounted between said spaced plate members to releasably lock said pump unit to said base support means.

12. A pump unit as in claim 9 and further including movable latch means mounted on said pump units for selectively releasably locking said pump units to said base means in one position in which said drive means is in disengaged relation to said driven means, or in another position in which said drive means is in engaged relation to said driven means.

13. A pump unit as in claim 9, and further including a backing member disposed between said plate members, in opposed relation to said roller members, said roller plate including driven means thereon for engaging with the drive means on said base means when said pump unit is associated with said base means.

14. A pump unit as in claim 13 wherein flexible tubing is adapted to be disposed between said backing member and the roller members on said roller plate, and adjustable friction means mounted on said spacer means for frictionally holding said tubing against shift relative to said backing means.

15. A pump unit as in claim 10 wherein said roller plate is disposed adjacent said spacer means, and further including shield means for the gear means on said roller plate for protecting said tubing against wear.

16. A pump unit as in claim 13, and further including coacting means on said backing member and said plate members for removably mounting said backing member between said plate members.

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