CONCRETE PUMPING SYSTEM

From Concretepumping

modified form of pump, In which a single valve controls both the inlet and the outlet passages. In the said drawing. 10 indicates generally a concrete pump having a cylinder 11 provided with S an inlet passage 12 and an outlet passage II. The inlet passage II communicates with a valve housing 14 In which is mounted a plug member IB, constituting the inlet valve, and which is provided with a passage 11 adapted in the open position of 10 the valve (indicated in broken lines in Fig. 2) to aline with the passages 17 of the valve housing 14. Tlie valve plug IB is arranged to be oscillated from its restrictive full-line position Illustrated In Fig. 2 to Its open broken-line position and back 15 again by means of a valve arm II, a connecting rod assembly II, and a rocker arm 20, which is actuated by suitable cams within a housing 21. A feed hopper 22 surmounts the valve housing 14 and receives the plastic concrete from any ap- 20 propriate mixer. In similar manner the outlet passage II communicates with a valve housing 2B in which is mounted the outlet valve plug 21, having the passage 27 arranged to aline with the passages 21 of 25 the housing 2B, and to be moved back and forth between its full- and broken-line positions, Illustrated in Fig. 2, by an arm 20, connecting rod 10, and a rocker arm and cams located on the far side of the machine. The discharge pipe or con- 30 duit II is connected to the outlet valve housing 2B, and at a point sufficiently removed from the pump may be provided with a fitting 12, upon which may be mounted the air dome or other pulsation damping device II. 35 During the pressure stroke of the pump piston 14, the valves IB and 20 occupy the positions shown in Fig. 2, with the inlet valve IB in its most restrictive position, and the outlet valve 20 in its fully open position. As the piston 14 reaches the 40 end of its pressure stroke, as indicated in Fig. 3, the cams actuate the respective rocker arms such as 20, the connecting rods 19 and 30, and the valve arms 10 and 29, to move the valve plugs IB and 20 In a clockwise direction from the full-line 45 positions of Fig. 2 to the broken line positions shown therein. At some time during this operation the valves may occupy substantially the positions illustrated in Fig. 3, in which it will be observed that neither valve imposes much restric- 60 tion in the passages controlled by it; and it is during the interval that the valves are approaching and leaving these positions that "back-slip" may occur if the pulsation damper be located in its usual place on or immediately adjacent the 55 pump. On the other hand, if it be located a suitable distance from the pump, as indicated in Fig. 1, the inertia of the mixture within that portion of the conduit II between the outlet valve 20 and fitting 12 will be sufficient to resist the pres- 00 sure built up in the air dome 33, and which would tend to force the mixture back toward the pump on the suction stroke of the piston. Obviously, the same condition permitting of " back-slip" will be present in the modified type 05 of pump illustrated in Fig. 4, wherein a single valve IB controls both the inlet passage 12 and the outlet passage 13, since as the said valve moves from the full line position to the broken line position shown therein, and vice versa, the two passages may be simultaneously open a sufficient time to allow the objectionable backward movement of the material being pumped. The fi present invention is therefore of value in connection with this form of pump. As above stated, the exact distance the damper is located from the pump may, vary, depending upon the character of the mixture being ban- 10 died; however, I have found that distances ranging from 25 to 100 feet give satisfactory results with all concrete mixtures now in common use when pumping through a five inch discharge line. 16 It is obvious therefore that those skilled in the art may vary the precise arrangement of the various instrumentalities without departing from the spirit of the invention, and it is not wished to be limited to the details of the above disclosure, 20 except as may be required by the claims. What is claimed is:— , 1. The combination with a pump for concrete and similar plastic materials having valve controlled inlet and outlet passages which at certain 25 times in the operation of the pump may be simultaneously open, and a pulsation damping device, of longitudinally extended connections between said pump and device arranged to contain a quantity of the material being pumped 30 sufficient that the inertia thereof and the friction between said material and the walls of said connections may over-come the back pressure exerted by said damping device and prevent back- slip of said material in said passages when they 35 are simultaneously open. 2. A pumping system for concrete and plastic materials having characteristics similar thereto, comprising a pump having valve controlled inlet and outlet passages which at certain times in the 40 operation of the pump may be simultaneously open an amount sufficient to permit of the plastic material flowing backward therethrough; a discharge conduit leading from said pump; and a pulsation damping device communicating with 45 said conduit at a distance from said pump sufficient that the inertia and friction of the plastic material in said conduit between the pump and the damping device may resist the back pressure exerted by the lattter to the extent necessary to 50 prevent back-slip of the material through said passages when they are simultaneously open. 3. In a pumping system for concrete and plastic materials having characteristics similar thereto, a pump having valve controlled passages which at 55 certain times in the operation of the pump may be simultaneously open; a discharge conduit leading from said pump; and a pulsation damping device communicating with said conduit at a distance of at least twenty five feet from said pump, QQ whereby the inertia and friction of the mixture in said conduit between the pump and the damping device may overcome the back pressure set up by the latter and prevent back-slip of the mixture through said pump passages when they are si- 05 multaneously open. CHARLES F. BALL.Loading...Loading...No Text