US3033123A - Apparatus for handling a paste-like material containing a gas - Google Patents

Description

May 8, 1962 APPARATUS FOR HANDLING A PASTE-LIKE MATERIAL CONTAINING A GAS J. KINZELMAN 3,033,123

Filed Dec. 19, 1957 /N VE N TOR.

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United States Patent Office 3,033,123 Patented May 8, 1962 APPARATUS FOR HANDLING A PASTE-LIKE MATERIAL CONTAINING A GAS Joseph Kinzelman, Northbrook, 111., assignor to Plastering Development Center, Inc., Chicago, 111., a corporation of Illinois Filed Dec. 19, 1957, Ser. No. 703,969

6 Claims. (Cl. 103-195) This invention relates to apparatus and method for handling a paste-like material containing a gas, and, more particularly, to that useful for pumping a substantially continuous and uniform stream of such material.

For many years, there has existed a problem in the handling and provision of streams of paste-like materials containing gases such as plasters and other cementitious mixes, as for application to building walls, ceilings, and the like. The problem revolves about the compressible nature of the mix. The compressible nature of the mix stems from the gas that it contains, the occluded gases being necessary to provide suitable internal lubrication in the mix when it is handled prior to mechanical application.

The problem becomes especially acute when positive displacement devices are employed to handle the Such devices, however, are preferred, since they can readily employ the high pressures needed to move sluggish streams such as plasters, and the like. Where, for example, a dual cylinder and piston unit apparatus is employed, it has been characterized by uneven rates of discharge of the compressible material. The ordinary operation of such a device would have one cylinder pumping while the other is discharging. However, because of the compressibility of the mix, there is a hiatus between the commencement of the pumping stroke and the actual discharge from the cylinder in which the pumping stroke has commenced.

The above-referred-to hiatus produces an interruption in the flow of paste-like material which can be especially bothersome when the material is being applied overhead. The decrease in flow may even result in the material not reaching the ceiling, but instead falling downwardly on the operator. Thus, an apparatus embodying positive displacement mechanisms that could overcome the problem of intermittent flow, would be especially desirable.

It is an object of this invention to provide a novel method and apparatus which overcome the problem outlined above. :Another object is to provide an apparatus embodying positive displacement mechanisms that provides a substantially continuous and uninterrupted flow of material of a paste-like character and containing a gas. Still another object of this invention is to provide an apparatus and method that are able to provide a continuous and uniform flow of paste-like materials containing gases where successive batches or runs of the material contain varying amounts of gas.

A further object is to provide an apparatus including three compression chambers which cooperate to provide a positive flow of a paste-like material containing a gas but without the flow interruptions heretofore considered implicit in such positive displacement structures. A still further object is to provide apparatus of the character described in the object set forth immediately above and in which a novel combination of working elements cooperate to provide a compact, rugged and superior operating structure. Other objects and advantages of this invention will be seen as this specification proceeds.

This invention will be explained in conjunction with an illustrated embodiment in the attached drawing, in which FIG. 1 is an elevational view of an apparatus embodying the teachings of this invention;

FIG. 2 is an enlarged cross sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a cross sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a schematic representation of the apparatus shown in greater detail in FIGS. 1-3.

In the illustration given, the numeral 10 designates generally a cylindrical housing which includes two portions 11 and 12 separated by an intervening bulkhead 13 and closed at opposite ends by end covers 14 and 15 located at the bottom and top ends as shown, respectively. A plurality of tie rods 16 extend between the end plates 14 and 15 to provide the rigid structure. Tie rods16 extend through arcuately disposed openings in the end plates and are secured in position by nuts 17.

The casing 10 serves as a pump for gas-containing pastelike material such as plaster or other cementitious compounds and, in the illustration given, the lower portion of HG. l is provided with a paste inlet at 18 and an outlet at the upper portion at 19, the outlet also being seen in FIG. 2. conventionally, inlet 18 may be communicated to a hopper and outlet 19 communicated to a hose through which the paste-like material is dispensed.

The structure provided in the upper portion of FIG.

' 1 and above end plate 15 which is designated generally by the numeral 211 represents one form of apparatus for reciprocating a piston rod carrying pistons within cylindrical housing 113.

Before proceeding with a detailed description of the various component parts of the apparatus as can be seen in FIGS. 2 and 3, it is believed that a general description of the mode of operation as can be better appreciated from schematic representation in FIG. 4 will be helpful in understanding the invention and the elements employed in practising it. For that purpose, the following description is given.

In FIG. 4, there is seen a cylindrical casing corresponding to cylinder 11 and which is designated in FIG. 4 as 111. A casing corresponding to cylinder 12 is designated in FIG. 4 by the numeral 112. A bulkhead is seen to exist between cylinders 111 and 112 and is designated by the numeral 113. A piston 121 is reciprocably mounted within cylinder 112 and a second piston designated 122 is re ciprocably mounted within cylinder 111. Pistons 121 and 122 are rigidly interconnected by means of a common piston rod 123 and a second piston rod extends upwardly from piston 121 and which is designated 124. Piston rod 124 is adapted to be connected to a source of motive power for reciprocating the two pistons. Three check valves are seen in the schematic representation of FIG. 4. One check valve designated by the numeral 125 is located in the end wall of cylinder 111. A second check valve 126 is located in piston 122, and a third check valve is located in bulkhead 113 and is designated 127. Each of these check valves is so oriented as to permit flow of pastelike material only upward in the schematic illustration given. Thus, check valve 125 operates to permit only entry of paste into chamber or cylinder 111 from an external source such as is designated by the numeral 118. Material passing through the apparatus of FIG, 4 issues from cylinder 112 to outlet 119.

It is to be noted that the two pistons define three chambers which for the sake of convenience will be designated by the capital letters A, B and C, chamber A being a chamber of variable internal volume defined by piston 122 and the bottom end wall of cylinder 111, chamber B by piston 122 and the top end Wall of cylinder 111 (i.e., bulkhead 113), and chamber C being defined by the bottom end wall of cylinder 112 (bulkhead 113) and piston 121. When the piston assembly is at its lowermost position, it starts moving upwardly and paste is drawn in through valve 125. When the piston assembly (i.e.,

J pistons 121 and 122 and piston rods 123 and 124) reaches the extreme top position and thereafter starts downwardly, valve 125 closes and valve 126 opens, and paste flows from chamber A into chamber B. Since the volume in chamber A is diminishing at a greater rate than the volume in chamber B is increasing due to the volume taken up by the piston rod 123, the paste in communicated chambers A and B is compressed. This compression occurs after one or two complete strokes of the piston assembly, since the initial strokes merely fill the apparatus with paste. Chamber B decreases in volume more rapidly than chamber C increases, so that when the piston assembly moves upwardly, a portion of the paste issuing from chamber B goes into chamber C to fill the same while the remainder of the paste issuing from chamber B flows through outlet 119. Optimum results can be obtained when chamber C has a maximum internal volume change equal to one-half of the maximum internal volume change of chamber B. In such a case, one-half of the paste is delivered to outlet 119 on the upstroke (this issuing from chamber B) while the same amount is delivered during the downstroke from chamber C. Departure from the indicated volumetric ratio can be compensated for by making corresponding changes in the time relationship for the up and down strokes.

In the operation of the apparatus generally described above, the opening of valve 126 in piston 122 on the downstroke of piston 122 establishes communication between chamber .A and chamber B, these two chambers thereby becoming one large chamber which is steadily reduced in gross volume by the space occupied by piston rod 123. It is to be immediately appreciated that the farther piston 122 travels downwardly, the more piston rod 123 is inserted into the larger chamber defined by chambers A and B. Concurrently, chamber C is isolated by the closure of valve 127. The material in chamber C, therefore, is forced out through outlet 119 because the volume of chamber C is decreased through the entry of piston 121 thereinto. On the upstroke of the piston assembly, valve 126 closes, thereby isolating chamber A from chamber B while valve 127 opens to establish communication between chamber B and chamber C. These two last-mentioned chambers together form a large chamber which is steadily reduced in gross volume because the increase in volume of chamber C is smaller than the decrease in volume of chamber B. In the specific illustration given, this is immediately apparent, since the diameter of piston 121 is smaller than the diameter of piston 122 and since they are connected, the strokes are the same. The excess material in the larger chamber defined by chambers B and C is, therefore, forced out of outlet 119. Concurrently with the communication of chambers B and C, chamber A, which is increasing in volume through the upstroke of piston 122, is characterized by a reduced pressure. This reduction in pressure allows the atmospheric pressure operating against the source of paste material to open valve 125 and force material to flow into chamber A.

In operation, the downward movement of the piston assembly is stopped when pressure developed within chamber B is just equal to that in chamber C. It is to be appreciated that an undesirable pulsation would occur if the maximum pressure developed in chamber B exceeded that in chamber C, since then valve 127 would be opened on the downstroke rather than just the upstroke of the piston assembly and, therefore, paste from both chambers B and C would be delivered to outlet 119. A number of devices can be employed for this purpose. Schematically represented in FIG. 4 (the upper left-hand corner) is one such structure. There, the numeral 130 designates an arm extending laterally from piston rod 124. Arm 130 is in sliding engagement with a guide rod 131 on which are positioned collars 132 and 133 at the upper and lower portions, respectively. Rod 131 is reciprocably supported by valve housing 134, which in turn can be conveniently supported on cylinder 112. Valve housing 134 contains suitable pressurized fluid-regulating means to cause reciprocation of the piston assembly. Thus, as piston 121 proceeds downwardly, arm ultimately engages collar 133, signalling the regulating means in housing 134 to reverse the travel of the piston assembly. In the same manner, engagement of arm 130 with the upper collar 132 produces another change in the direction of travel of the piston assembly. Collar 133 can be adjustably mounted on rod 131, permitting variation of the stroke of the piston assembly for materials of different compressibilities. Although the operation of this assembly has been set forth in terms of handling a paste-like material containing a gas, it is to be appreciated that it serves equally well for positively displacing other compressible materials requiring a substantially steady flow.

As pointed out above, the setting of the collar 133 or other stroke-limiting device, is dependent upon the compressibility of the paste-like material being handled. A paste-like material containing relatively little gas might be suitably compressed in chamber B by only a partial downward movement of the piston assembly. Mixes with greater compressibilities would, therefore, require a greater stroke on the part of the piston assembly.

Referring now to FIG. 2, an embodiment of the invention is seen that is the counterpart of the schematic representation seen in FIG. 4. For example, in FIG. 2, cylinder 11 defines two compression chambers A below piston 22 and chamber B above piston 22. Cylinder 12 defines chamber C and the counterpart of piston 121 of FIG. 4 is a hollow ram 21.

Focusing now on the bottom portion of FIG. 2 it is seen that end-plate 14 is provided with an opening 14a extending therethrough which is closed by a check valve designated generally by the numeral 25. Check valve 25 includes a rigid core portion 25a surrounded by a resilient portion 25b which are adapted to engage the inwardly tapered side wall of opening 14a. Valve 25 is also equipped with a stem- 25c which is guided along the axis of opening 14a by a guide bracket 25d secured to end-plate 14. Angle-shaped member 25:; serves as a stop for the downward movement of valve 25.

Proceeding upwardly in FIG. 2, the next element is piston 22 mounted on the end of piston rod 23, piston 22 being slidably mounted within cylindrical housing 11. Threadedly atfixed to the end of piston rod 23 is a piston carrier 22a which is a cylindrical-like fitting equipped with outwardly-extending lug 22b which receives four bars 220 which perform a dual purpose in that the they both support the piston body 22:! and act as a guide for the piston check valve 26. Check valve 26, like check valve 25, is provided with a metallic core portion 26a, a resilient outer portion 26b, and a stem 26c. Stern 2150 slides in a washer assembly 26d which is equipped with laterally-extending arms 26a which engage bars 22c and guides valve 26 along the axis of piston rod 23 and opening 222 in piston body 22d which serve as a seat for valve 26. Piston body 22d is provided with a suitable perimetric seal to insure sealing engagement of piston body 22d with the inner wall of cylinder wall 11.

At the upper end of cylinder 11, and connecting the same to cylinder 12, is bulkhead 13, which also serves to isolate one cylinder from the other and provide communication therebetween by means of a check valve generally designated 27. As can be appreciated from a consideration of FIG. 3, bulkhead 13 is provided with a plurality of openings 13a extending therethrough which are arcuate in form and disposed in a circular pattern. Bulkhead 13 is provided with a recess in the upper interior portion as at 13b which provides a mounting for a valve seat 13c which has openings therein aligned with openings 13a and bulkhead 13. Valve 13c is secured to bulkhead 13 by a plurality of bolts 13d. Valve 13c and bulkhead 13 are beveled at their inner mating surfaces to provide a V-shaped recess which receives and supports a seal 23a for piston rod 23.

The moving element of valve 27 is essentially a cylindrical cage provided by upper ring 27a, lower ring 27b, and connecting stem 27c. Stems 27c pass through openings 13a in bulkhead 13 and corresponding opening in valve 13 and in addition support a third metal ring 27d about which is positioned a resilient ring 27s. A valve structure of this type is set forth in greater detail in the co-owned, copending application of Lloyd H. Hobson, Serial No. 709,300 filed January 16, 1958, now Patent No. 2,949,928 and reference is hereby made to that application. Rings 27a and 27b are provided with a cen: tral opening that permits a sliding fit with piston rod 23 and which permits rings 27a and 27b to act as glides to direct valve 27 along a path parallel to the axis of the piston rod 23.

Piston rod 23 is equipped with a threaded recess 23b at the upper end thereof which receives a threaded projection 21b of ram 21, thereby rigidly connecting ram 21 and piston 22 in a manner analogous to the connection between pistons 121 and 122 in FIG. 4.

The cylindrical housing which, with ram 21, defines chamber C, is provided by cylinder 12 and outlet fitting 19a. Outlet fitting 19a is equipped with a laterally-extending bore 19 which serves as an outlet for paste-like material from chamber C. The upper end of outlet fitting 19a is provided with a central opening 19b which permits reciprocation therein of ram 21. The upper surface of outlet fitting 19a is beveled and, in cooperation with end-plate 15, provides a recess for the receipt and mounting of a ram seal 190.

Ram 21 is reciprocated by introducing a pressurized fluid on one side or the other of a stationary piston 26a supported on a hydraulic piston rod 20b (seen also in FIG. 1), piston 26a being slidably received within ram 21. To force ram 21 downwardly, and hence the entire piston assembly including piston 22, pressurized fluid is introduced through the hollow central portion of rod 2% while upward movement of ram 21 and the piston assembly is etlected by introducing pressurized fluid against the upper side of piston 20a through inlet port 200. For this purpose, a pressurized fluid such as oil can be conveniently used with conventional valving arrangements to apply pressure to one port while permitting a discharge from a second port, i.e., when fluid is introduced into port 200, the hollow piston rod 20b is vented to a sump, or the like.

Providing an upper end closure for ram 21 is a cylinder end-fitting 21c which has a laterally-extending bore therein providing port 200. Fitting 21c is threadedly connected with ram 21 and is provided with an axial bore permitting sliding movement of fitting 21c on piston rod 20b. Housed within the axial opening of fitting 210 is a packing gland 21d and confined therein by a flat gland retainer plate 21e suitably anchored to fitting 21c.

Piston rod 2% is maintained in a position along the axis of cylinders '11 and 12 by the cooperation of base plate 28 and outlet fitting 19a which are tied together by means of tie rods 29. These tie rods also secure seal 19c and end-plate 15. This structure insures that ram 21, which is slidably mounted on stationary piston 20a, will reciprocate along the axis of cylinder 12.

The operation of the device shown in FIGS. 1-3 is analogous to the operation of the schematic representation of a simplified device shown in FIG. 4. For example, upward movement of the piston assembly which includes piston 22, piston rod 23 and ram 21, induces a flow of paste-like material into chamber A through inlet port or opening 14a, valve 25 being open (its position opposite to the one shown). Upward movement of the piston assembly also results in the closing of check valve 26 in position 22 and the opening of check valve 27 in bulkhead 13 so that a paste-like material contained in chamber B is transferred into chamber C which is expanding due to the retraction therefrom of ram 21.' However, the expansion of chamber 0' is insuflicient to accommodate all of the material discharged from chamber B to check valve 27, so that a portion of the material introduced into chamber C is released to outlet 19. Upon downward movement of the piston assembly, check valve 27 is closed so that the decrease in internal volume of chamber C due to the receipt thereinto of ram 21 forces material previously contained in chamber C out of outlet 19, thereby maintaining a continuous stream of the desired paste-like material. Simultaneously with the discharge effectuated by the inward movement of ram 21 into chamber C, the downward movement of piston 22 closes inlet check valve 25 and opens the check valve 26 in piston 22, thereby eflectuating a transfer of pastelike material from chamber A into chamber B. The entrance of piston rod 23 into the larger chamber defined by A and B causes compression of the paste-like material therein. Without such compression intermediate the intake and discharge, there would occur the undesirable hiatus in flow characteristic of previously-employed posi tive displacement mechanisms.

As indicated above, a pressurized fluid can be employed to reciprocate hollow ram 21. The reciprocation of hollow ram 21 under such circumstances not only serves to discharge material from chamber C, but at the same time permits heat exchange to occur between the material being pumped in chamber C and the pressurized fluid within hollow ram 21. This is particularly true during the downward stroke of ram 21 (as seen in FIG. 2), since then the material in chamber C, in etfect, flows along the length of ram 21 which is stroking in an opposite direction to reach outlet 19. To aid in this heat exchange, ram 21 is constructed of a thermally conductive material, preferably a metal such as steel. The importance of this heat-exchange can be appreciated from the fact that conventionally employed hydraulic fluids such as the oils ordinarily used for reciprocating ram 21, have a maximum operating temperature in the range ISO- F. Because of this limitation, it has been the practice in the past to equip hydraulic systems with some means for cooling the pressurized fluid, since there is always a certain amount of power applied to the hydraulic system which is converted to heat energy. This heat energy, if undissipated, accumulates and, after a period, raises the temperature of the hydraulic fluid above the allowable range. A conventional expedient, for example, is to pass the hydraulic fluid through an air-cooled radiator, or the like, to remove the undesirable heat. The problem of heat accumulation is further aggravated when the hydraulic system is employed to operate a device at less than maximum capacity. For reasons of economy, the prime mover in the hydraulic fluid system is generally proportioned to operate at a rating equivalent to the maxlmum operating characteristic of the device deriving power from the hydraulic system, and any lesser operatmg characteristic is normally accomplished by allowing part of the oil to return to the sump, or the like, by bleeding it oif the high pressure output. Thus, whenever the device deriving power is operating at less than maximum, the excess power put into the system is converted to heat, which also must be dissipated. For example, ordinarily, a hydraulic system employs a pump as a prime mover, with the pump operating at constant output. In the illustration given, the pumping apparatus for plaster might often be operated at less than maximum capacity, since there are many applications where the paste must be discharged at less velocity than that possible. In such a case, it is apparent that the hydraulic system fluid would soon be heated above a tolerable value if some meansv Were not provided to dissipate the heat.

In the practice of my invention, I have found that any heat introduced into the pressurized fluid in the hydraulic pressure system employed to actuate ram 21 is rapidly d1ssipated through the wall of ram 21 into the stream of fluid material flowing from valve 27 providing the inlet to chamber C upwardly through chamber C and along the length of ram 21 and finally discharging through outlet 19. It is to be appreciated that additional heat exchange can be conveniently obtained by elongating ram 21 and chamber C correspondingly, with the further location of outlet 19 a further distance from the inlet provided by valve 27.

The type of ram structure pictured in FIG. 2 also produces another desirable result in the dissipation of heat from the hydraulic fluid powering ram 21, in that ram seal 19c effectively clears the outer surface of the ram 21 of any adherent material. Once each cycle of the movement of ram 21, seal 19c literally scrapes off the adherent pastelike material so as to permit ram 21 to move into the mass of paste-like material in chamber C free of any heat-retarding layer. This could be analo gized to the prevention of laminar flow of paste-like material in chamber C which would materially lessen heat transfer between the pressurized fluid within ram 21 and the paste-like material surrounding ram 21 in chamber C.

In the illustration given, it is to be noted that heat transfer is achieved during both upward and downward strokes of ram 21. During the downward stroke, the ram 21 is entering the body of paste-like material confined within chamber C because of the closing of valve 27. During the upstroke of ram 21, paste-like material continues to flow past the face of ram 21, since the rate of decrease of chamber B is greater than the rate of increase of chamber C and material continues to move toward outlet 19.

- While in the foregoing specification an embodiment of the invention has been set forth in considerable detail for the purpose of illustrating the invention in a manner that it may be readily practiced by those skilled in the art, it is to be appreciated that the invention is susceptible of many variations while still being within the spirit and principles of the invention.

I claim:

1. In apparatus for the application of a paste-like material containing a gas, two piston-equipped cylinders disposed in axial relation, a piston rod interconnecting said pistons, a common end wall between said cylinders and equipped with a check valve permitting flow of paste-like material in only one direction, fluid pressure means coupled to one of said pistons for reciprocating the same, a flow port in each cylinder spaced from said common end wall, the flow port in one cylinder serving as an inlet and the flow port in the other cylinder sewing as an outlet, a check valve in the inlet flow port permitting flow of paste-like material only into the associated cylinder, a check valve in the piston of the inlet flow port-equipped cylinder permitting flow of paste like material only toward said common end wall, and means coupled to said reciprocation means for varying the stroke of the interconnected piston as a function of the compressibility of the paste-like material, the piston in the outlet flow portequipped cylinder being a hollow ram, the interior of which is coupled to said fluid pressure means, said ram also providing a portion of the end wall of its associated cylinder, the end wall so provided being opposite said common wall.

2. In apparatus of the character described, a cylinder equipped with a piston movably mounted therein, said piston being equipped with a check valve, a flow portequipped with an inlet check valve at one end of said cylinder, said inlet check valve being operative to permit flow of material only to said cylinder, an outlet at the other end of said cylinder, a check valve-equipped barrier intermediate the ends of said cylinder, said check valveequipped barrier defining a pair of chambers within said cylinder, a piston rod connected to said piston and extending through said check valve-equipped barrier, said piston rod including a hollow ram in the portion of said cylinder between said check valve-equipped barrier and said other end, a fluid pressure system coupled to the hollow inside of said ram for varying the pressure inside of said ram and operative to reciprocate said piston, and means responsive to the stroke of said ram and operatively connected to said system for adjusting the stroke of said ram.

3. In apparatus of the character described, a cylinder equipped at one end with a check valve permitting flow of material only into said cylinder, said cylinder being equipped with a hollow ram movable through the wall at the other end thereof, a transverse wall in said cylinder intermediate the ends thereof and equipped with a check valve, :1 piston rod attached to said ram and extending through said transverse wall, said piston rod carrying a piston on the side of said wall remote from said ram, said piston being equipped with a check valve, an outlet in said cylinder adjacent said ram, said check valves all being operative to permit material flow toward said outlet, a seal in the other end wall about said ram, and a fluid pressure system coupled to said ram for pressurizing the interior of said ram to move said ram and said piston simultaneously and relative to said transverse wall.

4. In apparatus of the character described, two cylinders disposed in axial relation, a common end wall between said cylinders and equipped with a check valve permitting flow of material only from one of the two cylinders to the other, the said one cylinder being equipped with piston means and the other cylinder being equipped with hollow ram means, a piston rod connecting said piston means and ram means, said piston rod extending through said common wall, fluid pressure means coupled to the ram means in said other cylinder for pressurizing the interior and for reciprocating the same, an outlet in said one cylinder remote from said common wall, an inlet in said one cylnider in the end thereof opposite said common end wall, a check valve in said one cylinder inlet permitting flow of paste-like material only into said one cylinder, a check valve in the piston means of said one cylinder permitting flow of material only toward said common end wall, and means coupled to said reciprocating means for varying the stroke of said ram means.

5. In apparatus of the character described, an elongated casing providing a closed-ended casing providing a cylinder at one end, a piston slidably mounted in said cylinder, a piston rod attached to said piston, an intermediate transerse wall in said casing, said piston rod extending through said transverse wall, said transverse wall in one end wall of said casing providing the end wall of said cylinder, check valves in said piston and cylinder end walls all operative to permit material flow only toward the other end of said casing, an outlet at the other end of said casing, the other end wall of said casing being apertured, a hollow ram slidingly, sealingly mounted in the aperture thereof and coupled to said piston rod, said ram being thermally conductive, and means for introducing pressurized fluid into said ram to move said ram and piston simultaneously and relative to said intermediate transverse wall.

6. In apparatus for the application of a paste-like material containing a gas, two cylinders disposed in axial relation and each equipped with piston means, a piston rod interconnecting said piston means, a common end wall between said cylinders and equipped with a check valve permitting flow of paste-like material in only one direction, a flow port in each cylinder spaced from said common end wall, the flow port in one cylinder serving as an inlet and the flow port in the other cylinder serving as an outlet, a check valve in the inlet flow port permitting flow of paste-like material only into the cylinder equipped with said inlet flow port, a check valve in the piston means of the inlet flow port-equipped cylinder permitting flow of paste-like material only toward said common end wall, fluid pressure means coupled to the piston means in the outlet flow port-equipped cylinder for reciprocating the piston means therein, said coupled piston means having a Kendall June 17, 1890 Prott Nov. 12, 1907 10 Lower Oct. 29, 1935 Rotter Nov. 15, 1938 Kitsman Mar. 23, 1943 Cartier Mar. 10, 1953 FOREIGN PATENTS Great Britain July 13, 1955

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