Pumps – Expansible chamber type – Mechanically actuated distributor
Reexamination Certificate
1999-12-23
2001-04-24
Freay, Charles G. (Department: 3746)
Pumps
Expansible chamber type
Mechanically actuated distributor
C417S900000, C138S114000
Reexamination Certificate
active
06220834
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a sliding device for a pump having two conveyance cylinders operating in counterstroke for conveyance of viscous materials supplied to the pump from a material feeding bin, and including a C-shape curved pivot pipe, an extension pipe, and a discharge conduit. The pivot pipe extends into the material feeding bin and at its upper end is connected to the extension pipe. The extension pipe projects over the back wall of the material feeding bin essentially parallel to the conveyance cylinders and, on its end opposite the pivot pipe, is connected to the discharge conduit via a pipe rotating connection. The pivot pipe is connected for pivoting so that its lower end, preferably provided with an anti-friction ring, is caused via a reversing mechanism to connect alternatively to the openings of the conveyance cylinders which are connected to the back wall of the material supply bin.
2. Description of the Related Art
Sliding devices of this general type (DE-C-21 62 406) are particularly suitable for use as mobile cement pumps because of their compact construction, wherein the extension pipe extends over the back wall of the material supply bin and forms a connection with the conveyor mast which rests on the front portion of the chassis, and wherein the material supply bin can be easily charged or fed from the back side of the vehicle chassis. Those parts of the sliding device which are subjected to high friction wear are easily accessible from the upper side of the material supply bin and thus can be changed out in a simple matter. The pipe extending beyond the back wall of the material supply bin serves in the known sliding devices on the one hand as transport pipe for the thick materials which are often abrasive and thus is subjected to a significant amount of frictional wear. On the other hand, the extension pipe has at the same time a support bearing function for the pivot pipe. In the case of increasing wear, that is, with decreasing wall thickness in the extension pipe, the integrity of the extension pipe decreases, so that a gradually increasing risk of rupturing occurs. The rupturing danger occurs above all when heavy, highly viscous cement is conveyed, and the conveyance forces acting on the extension pipe are corresponding large. A pipe rupture in this area is a problem insofar as it occurs outside of the material supply bin and thus requires an immediate cessation of the pumping operation.
SUMMARY OF THE INVENTION
Beginning with this state of the art, the invention is concerned with the task of improving a sliding device of the known type in such a manner that wear of the extension pipe does cause problems with the reliability of industrial operation.
The inventive solution is based on the idea, that the extension pipe, which is subjected to friction, is not subjected to any bearing function. In order to accomplish this, it is proposed in accordance with the invention to provide a support pipe which coaxially surrounds the extension pipe, is rigidly connected with the upper end of the pivot pipe, extends over at least a part of the extension pipe, which is supported on a pivot connection provided spaced apart from the back wall of the material supply bin, and which is releasably connected with the extension pipe.
In a preferred embodiment of the invention, it is envisioned that the extension pipe and the reversing lever of the reversing mechanism are releasably connected with the pivot pipe via a flange and that the support pipe is rigidly connected with the flange, preferably is welded thereto. In principle, it is possible that the extension pipe and the support pipe are releasably connected with the pivot pipe and the reversing lever of the reversing mechanism via a common clamping flange. In order to be able to mount and dismount the extension pipe in a simple manner, it is important, that the outer surface of the extension pipe and the inner surface of the support pipe form or define an annular clearance. The connection between the support pipe and the extension pipe can, with maintenance of the annular clearance, be stabilized in the manner, that the support pipe on its free end is wedged or forms a V shaped connection with the extension pipe. In particular, the support pipe can be releasably anchored at its free end to the extension pipe via a set screw. When, as a result of frictional wear, a leak occurs in the extension pipe, then material is extruded into the annular clearance during the pumping process. When at least a preferably downward directed radial wall opening is provided in the support pipe, at least in the area of its end nearest the pivot pipe, then a leak occurring in the extension pipe can be relatively easily detected from the outside. On the basis of the stabilizing effect of the support pipe, a pipe rupture is reliably avoided.
For increasing the frictional resistance, the extension pipe can be constructed in two parts, wherein the inner pipe is constructed to be friction resistant, preferably hardened steel, and the outer pipe is constructed of a softer, not hardened, steel. Since the curved pivot pipe on its inner side is not hardened, it is of advantage, when the extension pipe at least on the connecting side of the pivot pipe has a larger inner diameter than the pivot pipe, making possible a greater removal of material from the pivot pipe.
In order to improve the up-take of the bending forces occurring during the direction changing process, it is of advantage, when the reversing lever on its conveyance conducting side exhibits a corbeled or cantilevered support arm, upon which the support pipe is supportable. The support arm can thereby, with it's end supporting the support jacket, lie loosely against the support pipe or be releasably connected therewith.
The rotating connections supporting the support pipe are advantageously formed as slide mounts with exchangeable slide mount segments. Depending upon the diameter of the support pipe, or the extension pipe to be supported, more or less thick walled support shell segments can be employed.
REFERENCES:
patent: 2700988 (1955-02-01), Smisko
patent: 3509917 (1970-05-01), Gartner
patent: 3832097 (1974-08-01), Schlect
patent: 4178142 (1979-12-01), Schwing
patent: 4410013 (1983-10-01), Sasaki et al.
patent: 4431386 (1984-02-01), Fehler et al.
patent: 4502851 (1985-03-01), Calvin et al.
patent: 5114319 (1992-05-01), Faber
patent: 5746247 (1998-05-01), Schlecht et al.
patent: 0171796 (1986-02-01), None
patent: 2039603 (1980-08-01), None
Benckert Hartmut
Bührer Klaus
Hurr Hellmut
Freay Charles G.
Pendorf & Cutliff
Putzmeister Aktiengesellschaft
Solak Timothy P
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