CA1108008A - Pump - Google Patents

Abstract

Abstract of the Disclosure A fluid operated pump for concrete and similar materials comprising a pair of piston-cylinder units connected to a concrete housing having a single valve for controlling the charging and discharging of the material. The valve control element and the concrete housing are defined in a mating relationship for minimizing flow restrictions of the material moved through the housing. Other efficiencies in the fluid circuit structures and arrangements are provided.

Description

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l l 11¦ Prior Art and Summary of the Invention 12 This invention relates to pumps and more particularly 13 pumps adaptea for conveying building materials such as plaster, 14 concrete; mortar and sLmilar moist compressible materials.
15 The pump which is the sub`ject of the present invention ;
16 is an improvement over the concrete pump disclosed and claimed 17 in u. s . Patent ReO ~6~8~0 granted on March lO, l9~0 o The 18 aforementioned patent discloses the construction of a mobile 19 concrete pump that ha~ been widely accepted throughout the United States and in most of the commercially important ~oreign 21 countrie5. The concre~e pump disclosed in United States Patenk ;
22 Re. 26,820 is a pump which~is a hydraulicaliy operated pump of 23 the piston-cylinder class. The concrete pump includes a 24 material or concrete chamber having a single control valve element for controlling the charging and discharging of th~
26 I material in the material chamber. The material chamber is 27 provided for housing a single control element or what is 28l, commonly known as a ~lapper element, The flapper element may 29j` be a simple plate that performs ~he desired function of 30¦ controlling the material undergoing pumping for purposes of 31l, cha~ging and discharging the mat~rial~ The conveyance of ~2 l I . ~

1. 1 1 material such ~s concrete through the material chamber is an important consideration in the construction of a concrete pump.
The present invention provides an improved pump for conveying building materials such as plaster, concrete, mortar and the like and is an imporvement over the speci~ic types of r pumps described and claimed in U.S. Patent Re. 27,820.
In accordance with the present invention there is provided apparatus for pumping a moist granular building material, for example plaster, concrete, or mortar, and including-first and second pumping units;
a material housing having a substantially cylindrical chamber internally thereof, the housing including a material inlet and a material outlet communicating with the chamber, the hous.ing also having means connecting the chamber with the 5 pumping units;means for charging the cham~er ~hrough the inlet with the material to be pumped;
a valve element rotatably mounted within the chamber for movement between two alternate positions for controlling flow of material at the inlet and the outlet, the valve element dividing the chamber into two oscillating protions and alternately allow the por~ions to function with the pumping units as a means to charge the material t~erein and to discharge the material therefrom, the valve element being arranged in the chamber relative to the inlet and the outlet so that in each of said positions it isolates the respective portion of the chamber discharging material from communication with the charging m~ans but connects the said portion with the outlet, the ~alve element being a one-piece plate-like blade element having align~d ~ .

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- coaxial trunnions extending from opposite longitudinal edges thereof and being rotatably mounted thereby to swing about the trunnion axis between said two positions and having oppositely contoured shallow concave faces of preselected depth within a preselected perimeter of each lateral face thereof for mating with the adjacent walls of the chamber to form a conduit-like opening through the chamber for reducing flow restriction of the material conveyed through the chamber; and automatic means for operating the pumping units and for changing the position of the valve element in preselected timed relationship therewith.
The housing of the control element is constructed and defined with a large, removable cover permitting the flapper element to be readily removed for servicing and the like. In addition, the large cover opening allows the interior of the housing for mounting the valve element to be readily machined and thereby greatly simplifies the installation of the wear plates for the flapper element. More efficiency in the operation of the concrete pump has been realized by locating the tank storing the lubrication medium or water for the pumping units so that it is directly connected to the material or concrete cylinders thereof thereby eliminating the need for any additional power source for conveyîng the water to the point of use, such as when the lubricating medium or water is located at a re~.ote location from the pumping units. In additionat the relocation of the point of application of the driving hydraulic fluid fox the piston-cylinder pumping units increases the overall efficien~ of the hydraulic system and eliminates the need for certain hydra~lic seals required in the prior art hydraulic systems.
From a structural standpoint, the preferred enbodlment provides apparatus for pumping moist ccmpressible materials such as plaster, concre-te, mortar and the like wherein two pumping units are pro~ided. The pumping units are arranged within an ~3 ,.~.~

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` ' , ' ` . ' ' ` '' ~ ', '` ', ` '`' ' ' ` ' ellclos~d mat~rial housing having a material inlet means and mat~rial outl~t m~ans arrang~d on opposite sides of the cylindrical material chamber defined therein. The pump includes means ~or charging the material ~o be pumped into the material chamber. The material chamber includes apertures for placing each of the pumping units in direct communication with the material chamber. A single plate-like control member is swingably or rotatably mounted in the material chamber to subdivide the chamber for alternately allowing the individual subdivided portions to function wlth the pumping units as a means to charge and discharge material. The control member is further characterized as a plate-like element having aligned trunnions extending outwardly therefrom for rotatably mounting the control element in the ma~erial chamber and being constructed and defined from one-piece of material. The lateral ~aces of the element is constructed and defined with concave surfaces for matin~ with the adjacent surface of the cylindrical material chamber for defining conduit-like passages for reducing the flow restriction of the material conveyed throu~h the chambex.
The pum~i~ng units may be in the ~orm o~ piston-cylinder Ul~its wherein the material cylinders are in direct communication with the material chamber and a closed ~rolume is def ined behind the reciprocating piston heads. A lubricating fluid storage tank is mounted between ~he pumping units so as $o be coupled directly in communication with the closed e~ds of each material cylinder for permitting the lubricating medium to ~low in and oui of the closed volume behind the pistc~n heads in accordance with their positions without resorting to any addi~ional power source.

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These al-d other featurcs of the present invention may be morc fully appreciated when considered in the light of the following specification and drawings, in which:
FIG. 1 is a top plan view wi~h a portion shown in section, of the pump assembly embodying the present invention;
FIG. 2 is a cross-sectional view of the material chamber taken along the line 2-2 of Fig. l;
FIG. 3 is a cross-sectional view through the material chamber taken along the line 3~3 of Fig. 2;
FIGS. 4A and 4B when aligned as indicated aré a cross-sectional view through an entire pumping unit taken along the line 4-4 of Fig. l; .
FIG. 5 is a rear elevational view of the control valve~
~ounted on the pumping uni~s and taken in the direction of line 5-~ of Fig. l;
FIG. 6 is a partial, sectional view taken along the line 6-6 of Fig. l;
FIG. 7 is a partlal, sectional view taXen along the line 7-7 of Fig. 4B, and FIG. 8 is an exploded view of the principal elements of the material housing illustrated in Fig. 1.

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~8~8 1 ~he p~np of the present invention is particularly adapted

2 for pumpirlg moist, compressible materials ~u~h as l:uilding

3 materials, plaster, concrete, mortar, and the like. The pump

4 will be described in conjunction with the pumping of concrete.
The concrete pump may be mounted to the rear of the cab 6 of a motor vehicle or truck. In such an application the power 7 unit for the motor vehicle is employed as the primary power sourc 8 for~the concrete pump and i~ therefore provided with a drive 9 member coupled between the power ~nit ~or the motor ~ehicle and the concrete pump. The power unit may be an~ other type of 11 convenient unit w~en the pump lS not mo,unted on a motor vehicle, 12 such as an electric motor~ for example~
13 The concrete pump generally comprises a pair of pumplng 14 units which are mounted on opposite side$ of a material or concrete hopper~ The hopper~ as îs conventional, is,utili~e~
16 to receive and store.the,material or concrete to be pumped and t 17 supplied thèreto. , . . :
18 The pumping units are connected with a common material or .
19 concrete chamber for the~pumps!and are arranged in communication therèwith and with the~hopper to allow.the pumping units to be .
21 directly charged with the concrete to be pumped from the hopper 22 and to be discharged from the pumping units in response to their pumping strokes through a common outlet for the concrete 24 chamber. A,conduit is normally coupled to the outlet for 11 conveying the concrete to the point of utilization of the ', 26 concrete. The concrete chambex is provided with a single control valve that is adapted to assume two positions and thereby 28 subdivide the chamber into,two portions for allowing the 29 , alternate.charging and.discharging o the concrete to occur 30 ! substantially.si~ultaneously in each portion of the chamber.

The two positions of the single control valve are ef fect-.
ive for subst~ntially closing off one of the pumping uni~s from the hopper while allowin~ the same pumping unit to discharge concrete through the outlet. During this same interval, the other pumping unit is substantially closed off from the discharge out-let while being in communication with the hopper through the hopper port. The charging of a pumping unit results due to the drawing in of the concrete from the hopper as a resul~ of the suction created by the pumping unit to be charged being xetracted from its completed pumping stroke. The control valve is positioned by ~ fluid pressure motor in a position to allow the pumping unit to discharge concrete through the discharge outlet while the other pumping unit is drawing concrete from the hopper.
The pumping units are constructed in the form of fluid pressure pumping units and preferably are hydraulically operated piston cylinder units ehreby the units are charged during their return strokes. The pumping units are controlled by a fluid power control circuit, preferably a hydraulic circuit, adapted to control the alternate charging and discharging of the concrete into and out of the pumping units while controlling the position of the control valve.
The above structure and operation is a brief summary of ~he concrete pump which is disclosed and claimed in the afore-mentioned U.S. Reissue patent Serial No: Re 26,280, a more complete description of the construction of the mobiel concrete pump may be found in the specification of the said Patent.

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1 ¦ Now spe~ifically refexring to ~he drawing, the general 2 ¦ organization of the concre~e pump lO will be examined in detail.
3 ¦ The pump lO generally comprises a pair of pumping units A and 4 ¦ B arranged with a concrete chamber housing e having a single

5 ¦ valve control element or flapper element ~ rotatably mounted

6 ¦ within the cylindrical concrete chamber CC. .The concrete to be ¦ pumped is charged into the concrete chamber CC by means of the 8 ¦ hopper H arranged in communication therewithO The sequencin~
91 of the pumping units A and B is controlled b~ means of the 10¦ hydraulic drive means ~DM~ The hydraulic drive means HDM
11¦ functions with a pair of mechanically actuated valves shown as 12¦ the cycle valve CV and the sequence make-up valve S. A
13 storage tank ST for stcring a lubri~ating or cooling medium, 14 such as water~ for the pumping units A and B is mounted between the units A and B as illustrated in FigO lo 16 The pumping units A and B are arranged i~ a parallel 17 rel~tionship with the concrete chamber housing ~. The pumping 18 units A and B each comprise reciprocating piston-cylinder 19 assembles controlled so that their forward or power strokes are utilized fox pumping concrete through the housing C and 21 their return, or suction strokes~ are utilized to charge 22 concrete into the pumping unitsO The pumping units A and B
23 are both identically constructed and for the purposes of 24 understanding the present invention only one of the units need be examined in detail. To this end~ the pumping unit B is 26 shown in detail in Figs. 4A and 4Bo When the structure of 27 Fig. 4A is aligned with the structure o~ Fig. 4B~ the complete 28 ! assembly of thP pumping un~t B Wi 11 be appreciated. The 29 I pumping unit B comprises a material or concrete cylinder 12B
30 I having a reciprocating piston unit 13B mounted therein. The 31 .
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1 ! piston unit 13B comprises a pi~ton head 13HB mounted at the 2 end o the shaft 13SB. The concrete cylinder 12B is cl~sed at 3 one end, the left-hand end as illustra~ed in Fig. 4B, and 4 sealed by means of an ~loll ring 12-OB for enclosing the cylinder~
The shaft 13SB i5 arranged to reciprocate through the closed end of cyclinder 12B~ The remaining end of the material or concrete cylinder 12B is arranged in direct communication with 8 the concrete chamber housing C in order to receive the concrete to be pumped in the cylinder 12B. The piston head 13BH is ~ :
hyaraulically controlled to reciprocate in a sliding relation 11 ship with the concrete cylinder 12B for drawing in the concxete 12 to be pumped from the hopper H through the concrete chamber 1 housing C and then pumping it through the concrete chamber CC
14 through a discharge outlet DO~ ~hen the piston head 13HB is being retracted during the suction stroke rom the right-hand position towards the left end~ or closed end~-o~ the cylinder 17 12B, the concre~e is drawn into the concrete cylinder 12B
18 behind the piston head 13HB~ During the pumping strokes of the piston head 13H it ~avels from i~s left-hand end extremity, as illustrated in Fig~ 4B t~ the right` for pumping the concrete 21 previously drawn into the cylinder 12B ba~k through the 23 concrete chamber CC and out a disch~rge outlet~ .
24 From the above description~ it should be appreci-ated that there is a closed volume dPfined behind the piston head 13HB
when it is spaced from the closed end of the cylinder 12Bu 27 The closed volume is employed ~or receiving a lubricating and/~r 28 cooling medium behind the piston head 13HB a~ it reciprocate~
within the cylinder 12B~ as will be explained more fully 29 hexeinafter. A push/pull rod ass~mbly 14B is coupled to the 30 ~ p ston head 13HB and lS carried by the piston head. The rod ~1 ; 8 B

1 ~ assenbly 14B is mounted outside of the pumping unit proper and ~ -2 ¦ as illustrated in Figs. 4A and 4B is mounted on the top of the 3 ¦ pumping units A and B. The specific coupling of the push/pull 4 ¦ rod assemblies 14A and 14B to the piston heads 13H~ and 13HB is 5 ¦ best appreciated from examining Fig. 4b. A push-pull rod 14B
61 is mounted in a rod guide tube 15 secured adjacent the left-hand 71 end of the concrete cylinder 12B as best appreciated from .
~¦ examining Fig. 7O The sleeve 15 mounts an override spring 16 9¦ seated between a pair of spaced bushings 16B and ~urrounding 10¦ the sleeve enclosed poxtion of the push/pul~ rod 14B; see 11¦ Fig. 4a. The remaining end o~ the push/pull rod 14B is .
12 connected to a linkage assembly generally ide~tified by the 13 reference numeral 17B for operating one of the control valves 14 associated with the hydraulic drive means HDM. The push/pull rod 14B for ~he pumping unit ~4 is specifically coupled to i6 operate a cycle val~e ~V~ The push/pull rod 14A for the 17 pum~ing unit is similarly couplea to a linkage 17A f~r operating 18 a sequencing make-up oil valve S~ The hydraulic drive means for the pumping units A and B is diagrammatically represented 2 by a box HDM in Fig. 1 and is generally o~ the same construction 22 as that disclosed in ~he aforementioned U. 5. Patent Re~ 26J820 The hydraulic pressure provided by thedrive means HDM is 23 alternately applied to the two pumping units A and B so as to.
24 alternately power the corresponding piston heads 13HA an~ 13HBo The hydraulic pressure is also alternati~ely applied to the 26 opposite ends of a hydraulic cylinder 20 m~unted over the Il concrete chamber housing C for controlling the position of the ¦I single control element, or flapper element F~ in accordance 29 I with the alterna~e pumping strokes;of the pumping units A and B.

31 The hydraulic drive means HDM alternately pressurizes the ~2 I .
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1 pumping units A and B to cause one o~ the piston heads 13H~ or 2 13HB to move forward on a pumpinq or concrete discharge stroke, 3 while the closed loop arrangement of the hydraulic circuit will I f 4 cause the okher pumping unit or piston head to move in the 5 return or suction stroke for charging the pumping unit with 6 concrete ~rom the hopper ~O The cycle of operati~n is controlled

7 by the two push/pull rods 14A and 14B mounted with the pumping units A and B for operating the cycle ~alve CV and the sequence 9 make-up and valve S~ The cycle va- ~e CV when operated is effective for changing the position of the flapper element F
11 and the valving (nct shown) for reversing the direction of the 12 pumping units A and B. The push/pull rod 14A for the pumping 13 unit A actuates the valve S for aut~matically maintaining a 14 constant volume of oil in the closed hydraulic circuit so as to assure a full stroke o~ the pistons 13HA and 13HB. This 16 general type of operation ;s disclosed in the aforementioned 17 reissue Patent ReO 26~820~ .
18 The efficiency of the hydraulic circuit HDM is increased .
19 over prior art hydraulic circuits such as disclosed in Patent .
Re. 26~820 by coupling the hydraulic fluid to act against ~he 21 head side of the hydraulic pistons;see~FigO ~Bo In the 22 hydraulic circuit disclosed in PatPnt ReO 26/820 the hydraulic 23 pressure is developed to act on the rod side of the hydraulic 24 piston, see FigO 3 of Patent ~e. 26~820, or.example The circuit arrangement in accordance with the pxesent invention 26 results in more efficient operation since there are less 27 hydraulic line lossesO In addition, certain costs are 28 eliminated by operating with a very low hydraulic pressuxe 29 on the rod side of the piston~ n~mely, the elimination of the 3 requirement for a high pressure seal between the hydraulic 31 cylinder ana the concret cylinder; no~e col. 8~ lines 57~71. .. -.

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1 ¦ The water tank ST in accordance with the present invention 2 ¦ is mounted between the parallel arrangement of the pumping units 3 ¦ A and B with the concrete cylinders 12A and 12B. The water 4 ¦ tank ST is specifically illustrated in Figs~ 1 and 6 of the 51 drawings. The water tank ST is of a substantially L-shaped 6 configuration and is arranged to be in direct communication with . 7 the left-hand end of the concrete cylinders 12A and 12B, as

8 best appreciated ~rom examining Fig. lo The upstanding section .

9 of the L-shaped tank ST is provided with a cover 20~ The cover ~0 is ~ecured to the tank by means of a chain 21 fastened 11 between the cover and a fastener 21F~ as best appreciated from examining Fig. 6. T,he tank includes means for draining the 13 lubricating medium or water from the tank~ The means for draining the tank STI as lllustrated in Fig. 6~ is a manually operated stopper 22 mounting a drain aperture 22D provided in 16 the bottom wall of th~ upstanding portions of the tank ST. The 17 stopper 22 includes a handle 22H of an L-shaped configuration .
18 .that is accessible through the tank opening when the cover 20 is removed to readily allow the water in the tank to be drained 21 through the aperture 22Do It is necessary to have clear water in the cylinders to prevent damage to the pistons 13HA ~nd 22 13HB.

24 Important features of the present invention are the constructions of the concrete housing C and its eoacting single control element or flapper element F~ The ~oncrete housing 26 is internally constructed and defined to mate with the 27 configuration of the flapper element F so a~ to minimize any tendency for flow restriction of the material passing through 29 the chamber CO The construction o~ the concrete chamber C
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and the flapper element F is bes~ appreciated from examini~g 31 . .
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1 I Figs 2, 3 and 8~ The concrete housing C has a concrete 2 ~ chamber cylinder CC defined therein which houses the flapper 3 ¦ element F. The flappe.r element F is constructed ~f one piece 4 ¦ of material with coaxial trunnions YT arranged on opposi~e ~ J~ / L ~
: 5 ~ ~ of the rectangular plate--liXe element functioning as a 6 flapper element. The lower trunnion FT is rotatably mounted 7 in the concrete ~ousing C so as to mount the flapper or 8 rectangular portion of the element F adjacent the bo~tom wall 9 of the concrete chamber CC~ The upper trunnion FT is simil~rly mour.ted.
11 The coniguration of the element F for the above-mentioned 12 purposes is produced by the contouring of the lateral faces of 13 the rectangular plate-like element functioning as the flapper 14 element.F. Within a preselected area of the faces of the flapper element F a concavity is defined for mating with the 16 cylindrical wall surfaces of the concrete chamber CC within 17 the housing C. As best appreciated from examining Fig. 3, 1 the concave portion of the flapper element is in the form of 19 a shallow C coniguratîon. The contoured face of the flapper . ~ r ~a~
21 element F/ when arranged with the àdjacent~u~&ee of the 22 cylindrical concrete chamber forms a conduit-like opening through the concrete housing for minimizing any tendency for ¦
23 restricting the material or concrete flow through the chamber 24 CC. Since the flapper element F is constructed of one piece of I
ma~erial/ it is easier to machine and thereby the concentricities 26 can be more easily controlled than when several pieces haYe to be machined and assembledO
~8 i It should also be noted that the flapper element F is 29 I provided with corrosive resistant sleeves secured by welding 30¦ to the trunnions FT and FS. Th.e sleeves are identified in ~21 ii .

~ 8~ 8 1 Figs. 2 and 3 a~ sleeves ~S illustrated in their assembled 21 relationship with the concrete chamber C. The sleeves FS are 31 preferably cons~ructed of a chrome-plated material for corrosion 41 purposes. In addition~ the outer ends o~ the flapper elemen~ F
are tapered and provided with a hard facing overlay for the 6 complete lateral extent thereof for providing shearing edges 7 for the flapper element. The hard ~acing overlay is illustrated 8 in Fig. 2 and is identified as the portion ~OV on the opposite g ends of the flapper element Fo The flapper element F and the concrete ch~mber housing C
11 are also provided with wear means for minimizing the wear on 12 the flapper element F and the housing C per se. The wear means 13 comprises wear plates WP in the orm o di~cs, one of which is 14 mountea on the bottom surface of the cylindrical concrete chamber CC within the housing C~ A similar wear plate WP
16 is mounted to the top side o~ the cylindrical chamber as shown 17 in FigsO 2 and 3O The concrete housing C is provided with a 18 large cover CC that is secured ~o the top thereof by fasteners 1 and is therefore readily removableO As illustrated in Fig. 3, the cover CC is secured in position by means of fasteners 22.

22 The large opening provided upon the removal o~ the cover CC
23 permits the interior of the housing C to be readily machined 24 for providing a smooth surface. As a resulty the accuracy with which the interior surfaces of the housing C can be definea is closely controlled~ This permits the wear plate WP
26 'to be easily mounted and assembled in the desired relationship on the bottom surface of the concxete cylinder CCO On prior art 28 structures~ machining was so difficult to accomplish that the 29 wear plates were mounted on uneven. cas~ surfaces and had to be shimmed to provi~e even surfaces. The shimming was by means ~2 ~

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L0~ 3 1 ¦ o~ a putty-like material which required a high degree of skill 2 ¦ to accomplish. The remaining weax plate WP is advantageously 3 ¦ secured to the inside surface of the cover CC; see Figs. 2 ~ 3.
4 ¦ ~ portion o~ the upper trunnion FT extends ou~ of the c~ver CC
51 to allow it to be coupled to the control valve 20 for rotating 61 the flapper element F between its two positions. The control 71 element 20 is best illustrated in Fig. l mounted to the top 81 surface of the concrete chamber and is readily accessible.
91 The concrete chamber CC is also provided with a plurality of

10¦ wear pins WPI secured in the housing C at the four joints that

11¦ the edges of the flapper element F move into sliding engagement 1

12¦ with; see Fig. l~ for example~ .

13¦ For the purposes of cleaning out the housing C, a pair of

14¦ doors CD, one of which is illustrated in Fig. 8, permit.

15¦ access to the interior of th housing C on opposite sides of

16 the flapper element F. The door CD is s~cured to the door

17 opening CDO.by means vf a seal CDS This allows any residual 19 concrete left in the housing C after completion Gf the pumpîng operation to be readily cleaned out from both sides of the flapper element F. With the remo~al of the doors CD~ a tool 22 may be inserted into the openings C~O to scrape out ~he co~crete residue.
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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for pumping a moist granular building material, for example plaster, concrete, or mortar, and including:
first and second pumping units;
a material housing having a substantially cylindrical chamber internally thereof, the housing including a material inlet and a material outlet communicating with the chamber, the housing also having means connecting the chamber with the pumping units;
means for charging the chamber through the inlet with the material to be pumped;
a valve element rotatably mounted within the chamber for movement between two alternate positions for controlling flow of material at the inlet and the outlet, the valve element dividing the chamber into two oscillating protions and alternately allow the portions to function with the pumping units as a means to charge the material therein and to discharge the material therefrom, the valve element being arranged in the chamber relative to the inlet and the outlet so that in each of said positions it isolates the respective portion of the chamber discharging material from communication with the charging means but connects the said portion with the outlet, the valve element being a one-piece plate-like blade element having aligned coaxial trunnions extending from opposite longitudinal edges thereof and being rotatably mounted thereby to swing about the trunnion axis between said two positions and having oppositely contoured shallow concave faces of preselected depth within a preselected perimeter of each lateral face thereof for mating with the adjacent walls of the chamber to form a conduit-like opening through the chamber for reducing flow restriction of the material conveyed through the chamber; and automatic means for operating the pumping units and for changing the position of the valve element in preselected timed relationship therewith.

2. Apparatus according to claim 1, wherein each pumping unit is a hydraulically powered piston and cylinder unit and includes fluid pressure control circuit means for alternately pressurizing the pistons on a pumping stroke, the circuit means coupling the hydraulic fluid so as to act against the head side of the piston units.

3. Apparatus according to claim 1, wherein the pumping units are arranged with their axes parallel and each has a piston head mounted in a material cylinder having spaced ends so as to be reciprocated from one end of the cylinder to the opposite end thereof, one end of each cylinder being in communication with the chamber for receiving the material to be pumped therein and the opposite ends of each cylinder being closed, each piston end defining a closed, variable volume between the closed end and one end of the piston head in accordance with the position of the piston head in the material cylinder, and a lubricating medium storage tank being mounted between the pumping units so as to be directly coupled in communication with the closed ends of each cylinder for permitting stored lubricating medium to flow into and out of the said closed volumes behind the piston heads in accordance with their respective positions.

4. Apparatus according to claim 3, wherein the lubricating medium is water.

5. Apparatus according to any one of claims 1 to 3, wherein the housing has a removable cover for exposing the valve element which is removable from the housing when the cover is removed.

6. Apparatus according to any one of claims 1 to 3, wherein the housing includes wear means on which the valve element rotates.

7. Apparatus according to any one of claims 1 to 3, wherein the housing has a removable cover for exposing the valve element which is removable from the housing when the cover is removed, and wherein the wear means comprises a wear plate secured to the side of the housing opposite the cover and a wear plate secured to the cover.

8. Apparatus according to claim 1 or 2, including a lubricating medium storage means for the pumping units for direct coupling with the pumping units.

9. Apparatus according to claim 1 or 2, including a lubricating medium storage means for the pumping units for direct coupling with the pumping units, the storage means comprising a lubricating water storage tank mounted between the pumping units so as to be directly coupled in communication with the closed ends of respective cylinders of the pumping units for permitting the stored lubricating water to flow directly into the respective cylinders for filling the volumes defined behind each respective piston head of. the pumping units and to be moved back into the tank by the piston heads without requiring an additional power source therefor.

10. Apparatus according to claim 1 or 2, including a lubricating medium storage means for the pumping units for direct coupling with the pumping units, the storage means comprising a lubricating water storage tank mounted between the pumping units so as to be directly coupled in communication with the closed ends of respective cylinders of the pumping units for permitting the stored lubricating water to flow directly into the respective cylinders for filling the volumes defined behind each respective piston head of the pumping units and to be moved back into the tank by the piston heads without requiring an additional power source therefor, and including means for draining the water from the storage tank.

11. Apparatus according to claim 1 or 2, including a lubricating medium storage means for the pumping units for direct coupling with the pumping units, the storage means comprising a lubricating water storage tank mounted between the pumping units so as to be directly coupled in communication with the closed ends of respective cylinders of the pumping units for permitting the stored lubricating water to flow directly into the respective cylinders for filling the volumes defined behind each respective piston head of the pumping units and to be moved back into the tank by the piston heads without requiring an additional power source therefor, and including means for draining the water from the storage tank, and wherein the drainage means includes a drain stop accessible from the top of the tank.

12. Apparatus according to claim; 1 or 2, including a lubricating medium storage means for the pumping units for direct coupling with the pumping units, the storage means comprising a lubricating water storage tank mounted between the pumping units so as to be directly coupled in communication with the closed ends of respective cylinders of the pumping units for permitting the stored lubricating water to flow directly into the respective cylinders for filling the volumes defined behind each respective piston head of the pumping units and to be moved back into the tank by the piston heads without requiring an additional power source therefor, and including a removable cover for the tank.

13. Apparatus according to claim 1, wherein the pumping units are hydraulically operated and controlled pumping units and include hydraulic drive means for alternately placing them in a pumping stroke and a return stroke; the pumping units comprise piston-cylinder units in which the pistons are reciprocable between a pumping stroke and a return stroke in response to the hydraulic drive means; and push-pull rod means is mounted on the outside of each pumping unit and coupled to an individual piston to be reciprocated thereby, the push-pull rod means being coupled to the hydraulic drive means for controlling the cycle of operation of the pumping units.

14. Apparatus according to claim 13, wherein each rod means is coupled to an individual valve element for mechanically operating the valve in accordance with the positions of the rod coupled thereto.

15. Apparatus according to claim 1 wherein the automatic means for operating the pumping units comprises hydraulic drive means and each pumping unit comprises a material cylinder in communication with the material chamber and a piston head mounted in the material cylinder to be reciprocated from one end of the individual cylinder to the opposite end thereof in response to the hydraulic drive means which is coupled to the head sides of each piston head.

16. Apparatus according to any one of claims 1 to 3, and including wear pins secured in the cylindrical chamber at four locations, the two diametrically opposed edges of the valve element engaging two respective diametrically opposed pins in each of the said two alternate positions thereof.

17. Apparatus according to any one of claims 1 to 3, wherein the tips of the blade element each have a hard face overlay thereon for the complete extent, and are tapered for providing shearing edges.

18. Apparatus according to any one of claims 1 to 3, wherein the trunnions have corrosion-resistant sleeves secured thereto extending outwardly from the longitudinal edges of the blade element a preselected distance.

19. Apparatus according to any one of claims 1 to 3, wherein the trunnions have corrosion-resistant sleeves secured thereto extending outwardly from the longitudinal edges of the blade element a preselected distance, and wherein the sleeves are chromium plated.