Concrete pump
[45] Apr. l5, 1975 United States Patent [191 Bine coNcRETE P UMP This invention relates toa concrete pump consisting of two counter vacuum or counter pressure piston means respectively. whereby the working cylinder is alternately connected with a commonrvacuum side. and with one of the passageways leading to the pressure line. n  
  In a known embodiment, a separating wall extends through the vacuum suction passageway between the connecting pieces of a pipe for the pressure line so that an annular slide travels in a sealing movement on the upper front face of the vacuum passageway. The annular slide is vertically mounted on a blocking plate which is pivotalbly driven at the end of a switching shaft. While the annular slide interrupts the supply of concrete at one side of the separating wall and opens the other side, the blocking plate works counterclockwise thereto. This is achieved so that in the end position of the blocking plate. the annular slide alternately opens and interrupts the supply of concrete. In this manner, the working cylinders of two counter running vacuum and pressure piston devices whereby one is connected with a common vacuum side and with one of the passageways leading to the pressure line. Such an alternate switching arrangement has a number of disadvantages. The annular slide which moves on the upper front face of the separating wall is subject to a high degree of wear. The separating wall which separates the concrete supply passageway creates dead space. It is also difficult to sufficiently seal the annular seal around its edges.  
 Accordingly, the present invention overcomes the above mentioned disadvantages in providing a sliding plate which extends over the common vacuum side, and a blocking plate which laterally and alternately closes the passageways to the pressure line. Both are mounted on a switching or actuating shaft which runs parallel to the piston means.  
  It is therefore an object according to the present invention to provide a concrete pump which includes pressure and vacuum pistons which operate alternately in conjunction with a sliding valve plate to force concrete fed into the input of the pump out of a common output under high pressure.  
  It is another object according to the present invention to provide a concrete pump which is simple in design. reliable in operation and inexpensive in cost.  
  Other objects and features of the present invention will become apparent from the following detailed description considered in conn&#39;ection with the accompanying drawing which discloses the embodiments of the invention. lt is to be understood however that the drawing is designed for the purpose of illustration only and not as a definition of the limits of the invention.  
  ln the drawing wherein similar reference characters denote similar elements throughout the several views:  
  FIG. l is a longitudinal cross-sectional view through an alternating switching arrangement according to the invention;  
  FIG. 2 is a plan view of the device according to FIG. l;  
  FIG. 3 is a cross-sectional view taken along line A-B of FIG. 2;  
  FIG. 4 is a cross sectional view taken along line C-D of FIG. 2; and  
  FIG. 5 is a cross sectional view taken along line E-F of FIG. 2.  
  Referring to FIGS. 1-5, the concrete pump of the invention essentially consists of two counter moving vacuum or pressure piston means respectively. whereby the associated working cylinders l and 2 are alternately connected with a common vacuum inlet side 3, and with passageways S and 6 leading to a pressure line 4. Passageways 5 and 6 are located at the end of a pipe 7.  
  ln the invention. a sliding or pivotal plate 8 extends over the two working cylinders l and 2, and the common inlet side 3. Pivotal plate 8 is mounted on a switching shaft 9 running parallel to piston means I and 2. Furthermore, at the end ofswitching shaft 9 is mounted a blocking plate l0 which alternately opens and closes passageways 5 or 6 respectively.  
  In the position shown in FIGS. 2 and 3, sliding plate 8 closes theconcrete supply passageway 3 to the working cylinder l, and opens the passageway to working cylinder 2. The concrete supply passageway to pressure line 4 is opened through passageway 5 by blocking plate l0 while passageway 6 isblocked. Therefore, a suction or vacuum stroke is carried out by working cylinder 2, and a pressure stroke is performed by working cylinder l. After shaft 9 is switched` sliding plate 8 closes concrete supply passageway 3 and working cylinder 2, and blocking plate l0 closes passageway 5 in pressure line 4. In this manner, the vacuum or pressure piston means and their associated working cylinders l and 2 respectively, are alternately connected with a common suction side or opening 3 and with one of the open passageways 5 or 6 which are open with respect to pressu&#39;reline 4. Itis advantageous that blocking plate l0, which is vertically mounted on sliding plate 8, be pear shaped as shownin FIG. 3.y Blocking plate l0 extends from the upper outer edge of sliding plate 8 to cover one of passageways 5 or 6 respectively. In this way the plate forms the connecting wall of the concrete supply passageway 3 opposite pressure line 4. The flange end of pipe 7 with associated passageways 5 and 6 serves as a closure for switching stations 3 to l0, and as a pivot bearing for switching shaft 9. As can be seen in FIG. 4 a rib l2 extends from the pivot bearing between passageways 5 and 6. Two ribs 13, corresponding to the pivot angle of sliding plate 8 also extend from the pivot between passageways S and 6.  
  lt is another feature of the invention that switching shaft 9 be adjustable in axial direction on closure Il for bringing the blocking plate l0 in sealing engagement with ribs l2 and 13. Therefore, a simple seal is formed and maintained between the suction or vacuum side, and the pressure side.  
  The invention also provides that an intermediary plate l5 by provided between housing l4 of switching plate 3 to I3. This intermediary plate l5 is provided with abutment I9 which limit the pivotal movement of sliding plate 8. The engagement of the sliding plate 8 with its upper outer edge onto abutments 19 at the end of an adjustment movement lessens the wear on the switching station. Moreover, all parts can be easily assembled.  
  It is essential that closure 1l and intermediary plate l5 be mounted on housing 14 by screws 16 which are easily removeable. This facilitates a removal of all individual parts in the switching station in the event they have to be replaced. ln such a case, closure ll together with pipe 7 is removed.  
  It is also a part of the invention that housing 14 he provided with two longitudinal horesk I7 and 18 which at one end, connect to pipe 7 of pressure line 4 across passageways and 6, and open to concrete supply inlet 3, while at opposite end are connected totworking cylinders l and 2 of the piston means. ln this way, a compact switching station is obtained using the least amount of space possible.  
  ln a preferred embodiment` each of the pistons are coupled directly or indirectly to the drive shaft so that the sliding valve plate will close off the inlet of the passageway under compression while the locking plate will open its output to permit the concrete to flow into outlet member 7.  
  While only a single embodiment of the present invention has been shown and described it is obvious that other changes and modifications may be made thereunto without departing from the spirit and scope of the invention.  
 What is claimed is:  
 1.k A &#39;concrete pump comprising:  
 a hollow housing having at least two passageways formed therein, and an input opening communicative to each of said passageways;  
 a cylinder coupled to one end of each of said passageways;  
 a piston slidably disposed in each of said cylinders for compressive movement therein; v  
 , a drive shaft rotatably disposed in said housing and coupled to each of said pistons;  
 a funnel-shaped closure secured over the opposite end of said passageways defining the output of said housing, said Aclosure having a pivot bearing for pivotably securing one end of said drive shaft;  
 a pear-shaped blocking plate pivotably disposed for movement over the outputl member of said housing for alternately closing at least one of said passage-` ways, and opening, at least one of said passageways i communicative to a cylinder under compression; and  
 a sliding valve plate axially connected to said drive shaft for alternately opening and closing the input opening to each of said passageways, said sliding valve plate being connected to said blocking plate so as to cover and seal the inputopening of a passageway under compression, said sliding valve;  
 plate being moveable over the entire width of the input opening of the passageways, wherein `said funnelshaped closure additionally includes a first rib extending between the output of said passageways and a second pair of ribs connected to said first rib and defining the pivot angle of said sliding l valve plate.  
 2. The concrete pump as recited in claim l wherein comprising screws threadably coupled to said housing for detachably mounting said funnel-shaped closure and intermediate plate to said housing.&#39;  
  5. The concrete pump as recited in claim l wherein said passageways comprise longitudinal `bores formed within said housing and converging at the outputof the.