US3398693A

US3398693A - Concrete pumping apparatus

Info

Publication number: US3398693A
Application number: US569264A
Authority: US
Inventors: Kurt E Schumann
Original assignee: Danken Inc
Current assignee: Danken Inc
Priority date: 1966-08-01
Filing date: 1966-08-01
Publication date: 1968-08-27
Anticipated expiration: 1985-08-27
Also published as: DE1974431U; DE1653415A1; GB1123520A

Description

-Aug. 27, 1968 K. E. SCHUMANN CONCRETE PUMPING APPARATUS 5 Sheets-Sheet l MVENQTO QCM? dc/Qrqanq ,MJ/fm Filed Aug. l. 1966 CY-r o meyf K. E. SCHUMANN CONCRETE PUMPING APPARATUS 5 Sheets-Sheet 2 IMvEJu-ror/ QCUrV. QScUnzayU/L /W f 06W Cjh-Tonuoy/ Aug. 27, 1968 Aug. 27, 1968 K. E. SCHUMANN CONCRETE PUMPING lAPPARATUS 5 Sheets-Sheet 5 Filed Aug. 1,' 1966 'M VENT O k) Quarz/. @blu/1am 9 my, /WJa/w CAT-roremavf Aug- 27, 1968 K. E. SCHUMANN 3,398,693

CONCRETE PUMPING APPARATUS Filed Aug. l, 1966 5 Sheets-Sheet 4 m A @duri/6. chunia 0L @T1-Grams. f`/

Aug. 27, 1968 K. E. SCHUMANN CONCRETE PUMPING APPARATUS Filed Aug. l, 1966 5 Sheets-Sheet 5 "Mlm fg/0M C-rvorzloayf VENT-r or; @fori/?. UCJ? u 3,398,693 CGNCRETE PUMPING APPARATUS Kurt E. Schumann, Milwaukee, Wis., assignor to Danken, Inc., Hartland, Wis., a corporation of Wisconsin Filed Aug. 1, 1966, Ser. No. 569,264 14 Claims. (Cl. 103-49) ABSTRACT F THE DISCLOSURE A concrete pumping apparatus includes a pair of sideby-side pumps which reciprocate in unison but in opposite directions so that one pump sucks a charge of iiuent concrete from a hopper while the other pump forces a previously received charge into a delivery pipe. A valve for controlling the flow of concrete to and from the pumps is formed with a first closure oscillating back and forth beneath the hopper to establish communication between the latter and alternate ones of the pumps. The valve also includes a second closure swinging in a plane perpendicular to the first closure for establishing communication between alternate ones of the pumps and the delivery pipe, the arrangement of the two closures being such that one pump always communicates with and receives concrete from the hopper while the other pump is communicating with and feeding concrete into the delivery pipe.

This invention relates to concrete pumping apparatus of the type in which fluent concrete dumped into a hopper by trucks or a mixer is forced through a delivery pipe by a pair of reciprocating pumps and is delivered to areas inaccessible to trucks. More particularly, the invention constitutes an improvement over the pumping apparatus disclosed in Schumann Patent No. 3,181,469 in which the pumps reciprocate in unison but in opposite directions, and appropriate valving operable in timed relation with the reciprocation of the pumps alternatiely establishes communication between one pump and the hopper while establishing communication between the other pump and the delivery pipe so that one pump sucks concrete from the hopper while the other pump feeds concrete into the delivery pipe.

The general object of the present invention is to provide new and improved pumping apparatus of the above character which is more rugged and trouble-free in operation While being of simpler construction and more eiiicient in service use than prior constructions used for related purposes.

Another object is to provide an improved and simplified valve comprising a single movable member formed with a pair of closures which control the iiow of concrete into and out of the pumps and which, at the same time, move easily through the concrete and have an extremely long service life.

A more detailed object is to mount the valve member beneath the hopper for back and forth oscillation about a predetermined axis with one of the closures swinging along an arcuate path extending beneath the bottom of the hopper to admit concrete to alternate ones 0f the pumps, and the other closure swinging in a plane perpendicular to the axis for establishing communication between alternate pumps and the delivery pipe.

Still another object is to provide quick-connect couplings between the pistons and the piston rods of the concrete pumps to enable quick and easy removal of the pistons for purposes of cleaning or replacement.

A further object is to improve the stability of the pumping apparatus and to yreduce the set-up time required to put the apparatus in service use.

Other objects and advantages will become apparent from States atent l ice the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a fragmentary plan view of a concrete pumping apparatus embodying the novel features of the present invention.

FIG. 2 is a fragmentary side elevation of the pumping apparatus shown in FIG. 1.

FIG. 3 is an enlarged fragmentary cross-section taken along the line 3 3 of FIG. 2.

FIG. 4 is an enlarged fragmentary cross-section taken along the line 4 4 of FIG. 3.

FIG. 5 is a perspective view of one of the pump pistons.

FIG. 6 is a fragmentary exploded perspective view of the valve and part of the valve housing.

FIG. 7 is an enlarged fragmentary cross-section taken along the line 7-7 0f FIG. 1.

FIG. 8 is a fragmentary exploded view of the valve housing and the connection leading to the delivery pipe.

FIG. 9 is a schematic view and fluid circuit diagram of the pumping apparatus.

As shown in the drawings for purposes of illustration, the invention is embodided in a concrete pumping apparatus of the type in which iiuent concrete is dumped into a hopper 10 by trucks or a mixer and is pumped through a delivery pipe (not shown) to remote points and diicult to reach spots. Such apparatus is especially suitable for pumping concrete to the upper stories of multi-iioor buildings under construction, for pouring complicated architectural designs, and for related operations in which concrete is to be placed in areas inaccessible to trucks.

Herein, the pumping apparatus is carried on a trailer 11 comprising a rectangular horizontal frame 12 supported tandem fashion on Wheel assemblies including Wheels 13 journaled for rotation on stub axles 14 fastened near opposite ends of longitudinally extending lbars 15 on each side of the frame. The hopper 10 is supported near the forward end of the frame on a housing 17 (FIGS. l and 7) and is formed with an open lower end 18 which is similar in size and shape to the upper open end of the housing. Concrete flows from the opening in the hopper and into the housing through inlet ports 19 (FIGS. 6 and 7), and then to the concrete pumping mechanism to be forced by the latter into the delivery pipe which may be connected to a so-called Siamese pipe section 20 (FIG. l) communieating with the forward end of the housing through outlet ports 21 (FIGS. 3 and 8).

As shown in FIGS. 1 and 3, the concrete pumping mechanism comprises a pair of side-by-side

reciprocating pumps

22 and 23 including cylinders 24 extending longitudinally of the frame 12 and communicating at their forward ends with the rear of the housing 17 through intake ports 25 (FIGS. 3 and 6) to receive concrete flowing to the housing from the hopper 10. Mounted for reciprocation in each cylinder is a pump piston 26 fitting tightly but slidably within the bore of the cylinder and carried on the forward closed end 27 (FIG. 3) of a hollow tubular piston rod 28. The piston rods also serve as cylinders for hydraulically operated

actuating pumps

29 and 30 which reciprocate the concrete pump pistons 26 during the pumping operation. Hydraulic fluid for operating the actuating

pumps

29 and 30 is supplied by a fluid pressure pump 31 (shown schematically in FIG. 9) driven in a well known manner by a gasoline motor 33 and communicating with a reservoir 32 (FIGS. 2 and 6) carried on the rear of the frame.

By means of valving 35 (FIG. 6) disposed in the housing 17, each concrete pump cylinder 24 alternately communicates with the hopper 10 and the delivery pipe, rst to receive a charge of concrete from the hopper through one of the inlet ports 19 and one of the intake ports 25 as the associated piston 26 slides rearwardly, and then to pump the charge back through the intake port and into the delivery pipe through one of the outlet ports 21 as the piston slides forwardly. The pistons are reciprocated in unison but in opposite directions so that one piston pumps concrete into the delivery pipe on its forward stroke while the other piston is sucking concrete into its cylinder from the hopper on its return stroke. The valving includes

closures

36 and 37 for closing the outlet port of each pump while it is being charged in order to insure a complete lill, and for closing the inlet port of each pump as the latter is pumping in order to insure that the entire charge is fed into the delivery pipe.

In accordance with the primary aspect of the present invention, the ow of concrete into and out of the

pumps

22 and 23 is controlled by a new and improved valve 35 in which the

closures

36 and 37 are formed as a single integral unit and, at the same time, are arranged in the housing 17 in a novel manner such that the valve has a longer service life and moves more easily through the concrete than prior valves used for similar purposes. To these ends, the closures are integral with each other and are mounted within the housing to oscillate between two positions about a substantially horizontal axis in timed relation with the reciprocation of the pumps. During the oscillation of the valve, the irst closure 36 swings along an arcuate path extending over the axis and beneath the hopper to close alternate inlet ports 19, and the second closure 37 swings in a plane perpendicular to the axis to close alternate outlet ports 21. The disposition of the closures within the housing is such that metal-to-metal contact between the closures and the housing is minimized thus reducing the valve wear, and the closures are shaped so as to move through the concrete with a positive slicing action.

In this instance, the housing 17 for the valve 35 is a casting or fabrication comprising opposed parallel side walls 38 (FIGS. 6 and 7) interconnected at their rear edges by an upright and laterally extending rear wall 39. The upper edges of the housing walls are turned outwardly to form an upwardly facing flange 40 which is bolted to a complementary flange 41 turned outwardly from the lower end of the hopper 10 thus fastening the hopper to the housing. Projecting forwardly from the central portion of the rear wall is a substantially vertical partition 42 dividing the housing into a pair of laterally spaced and upright ow passages 43 and 44 which communicate with the opening 18 in the hopper through the 4upwardly opening inlet ports 19, these ports being defined by the partition and the side walls 38. At its lower end, the partition is formed with a rbase portion 45 having a rounded lower surface which gradually merges with the side walls to form an arcuately curved bottom for the housing. The intake ports for the pump cylinders are formed in the rear wall 39 near the lower ends of the flow passages and open into laterally spaced tubular pipes 46 (FIGS. 3 and 6) formed integrally with the rear wall and connected to the output or forward ends of the pump cylinders 24 as shown most clearly in FIG. 3.

Forming the forward wall of the housing 17 is a at upright cover plate 47 (FIG. 8) which is removably bolted to a substantially U-shaped spacer plate 48 (FIGS. 6 and 8) fastened to the front edges of the side walls 38 and the bottom wall of the housing. The cover plate completely closes the front sides of the passages 43 and 44 except for laterally spaced openings in the cover plate leading to the siamese pipe section 20. These openings constitute the outlet ports 21 (FIGS. 3 and 8) for the

pumps

22 and 23 and are alined with the intake ports 25 to establish a substantially straight liow path between the pumps and the siamese pipe section. The latter comprises a pair of separated and laterally spaced pipes 49 which are alined with the outlet ports and which merge into a single forwardly projecting spout 50 adapted for connection with the delivery pipe. Thus, the ow of concrete is from the hopper 10 to the ilow passages 43 and 44 of the housing through the inlet ports 19, and from the passages into the pump cylinders 24 through the intake ports 25. As concrete is pumped from the cylinders, it flows back through the intake ports, across the bottoms of the passages and into the pipes 49 through the outlet ports 21, and linally into the spout and the delivery pipe to be placed in the desired location.

In order to per-mit cleaning of concrete from the valve 35 and the housing 17 after each pumping operation, the Siamese pipe 20 is mounted to swing away from the housing to expose the outlet ports 21 so that water introduced into the top of the housing to flush the latter and the valve may drain out of the outlet ports. For this purpose, a pair of vertically spaced and outwardly projecting lugs 51 (FIG. 8) are formed on one of the side walls 3S of the housing and intert with lan ear 52 formed adjacent the rear end of the Siamese pipe. The pipe is hingedly connected to the side wall by a vertical pin 53 passing through holes in the lugs and the ear. At its opposite side, the pipe is fastened to the side wall by a removable bolt 54 or other suitable fastening means passing through holes for-med in lugs 55 and an ear 55a formed on the side wall and the pipe, respectively. Thus, by removing the bolt, the Siamese pipe may be swung away from the housing about the pin 53 to enable drainage of water and concrete directly from the outlet ports 21 when the valve and the `housing are ilushed for cleaning purposes. In addition, by swinging the pipe away from the housing and by unbolting the cover plate 47, the valve 35 is easily exposed for purposes of repair or replacement.

As shown in FIGS. 6 to 8, the valve 35 is keyed to the for-ward end of a horizontal shaft 56 projecting forwardly through the rear wall 39 and the partition 42 of the housing 17 and journaled for oscillation in a bushing 57 disposed in the partition just above the level of the intake ports 25. Fast on the rear end of the shaft is sa crank 58 (FIGS. l, 7 and 9) which is connected to a power actuated mechanism 59 operable to oscillate the valve between the two valve positions. In this instance, the mechanism 59 is fastened to the rear wall 39 exteriorly of the housing 17 and comprises a pair of pistons 60 and 61 (FIG. 9) slidable in a pair of

cylinders

62 and 63, respectively, and interconnected by a common piston rod 64. The latter is operably connected to the crank 58 by a pin 65 extending transversely through the rod and pivotally connected to the free end of the crank. Oil under pressure first is admitted to the cylinder 62 and then to the cylinder 63 to shift the rod 64 sidewise in opposite directions and, through the crank, to oscillate the valve between the two positions.

The valve is formed with a circular hub 66 (FIG. 6) fitting into a recess 67 in t-he partition, with an integral sector-shaped plate 68 extending radially and generally upwardly from the hub. Because of the spacer plate 48, the cover plate 47 is spaced forwardly from the front face of the partition 42 to deline a vertically extending slot 69 (FIG. 3) through which the sector plate 68 swings as the valve oscillates with the shaft 56.

The first valve closure 36 controls the flow of concrete from the hopper into the passages 43 and 44 by opening and closing alternate inlet ports 19, and is a curved metal plate integral with and projecting rearwardly from the upper end of the sector plate 68. In one position of the valve (FIG. 8), the curved plate 36 covers the inlet port 19 for the passage 43 to shut off the iiow of concrete from the hopper 10 to the pump 22, while in the other position of the valve (FIG. 7), this plate covers the inlet port for the passage 44 to shut off the ow of concrete to the pump 23. In each valve position, the curved plate extends between one of the housing side walls 38 and the partition 42 with the lower sides of alternate beveled ends of the plate seating against an insert 69a fitted in the top of the partition to prevent concrete from leaking into the passage across the top of the partition. The upper and lower surfaces of the plate are concentrically curved about the axis of the shaft 56 and, as a result, the curved upper surface slices smoothlj through the concrete and the lower surface passes in closely spaced relation to the top of the partition as the valve oscillates. To minimize metal-to-metal contact between the valve and the housing, the rear edge of the curved plate 36 rides in an arcuate groove 70 formed in the rear wall 39 and is spaced approximately 3%,2 inch from the top and bottom surfaces of the groove. This arrangement prevents concrete from flowing downwardly between the rear edge of the curved plate 36 and the rear wall 39 and yet prevents wear ywhich would be caused by the plate rubbing directly against the rear wall. In addition, the upper surface of the plate extends tangentially to the side walls 38 in each of the valve positions and thus the valve has no edges movin-g into abutting relationship with the side walls thereby minimizing crushing of rock between the valve and the housing. As a result, the service life of the valve is increased while the amount of power required to oscillate the valve is decreased.

Herein, the'dsecond valve closure 37 for controlling the outlet ports 21 is a paddle-shaped plate formed integrally with the hub 66 and disposed in the same plane as the sector plate 68. As the valve oscillates, the paddle plate swings through the vertical slot 69 between the partition 42 and the cover plate 47 with the rear face of the paddle plate passing in closely spaced relation to the forward face of the partition. The lower or outer end 71 of the paddle plate is concentrically curved about the axis of t-he shaft 56 and preferably is spaced approximately 1&2 inch from the complementary curved upper surface 72 of a recess cut in the lower portion of the spacer plate 48 on the housing 17 so as not to be in rubbing contact with the spacer plate. Because the paddle plate lies in a single plane and is relatively thin, it slices smoothly through the concrete as the valve oscillates and does not hinder movement of the valve to any appreciable degree. The paddle plate is sufficiently wide to cover one of the outlet ports 21 (FIGS. 3 and 8) in each of the two positions of the valve and is an-gularly spaced from the curved plate 36 such that, when the valve is positioned as shown in FIG. 7, the paddle plate closes the outlet port for the pump 22 while the curved plate 36 is closing the inlet port 19 for the pump 23. In the other valve position (FIG. 8), the plates are shifted through an arc of approximately 90 degrees and thus the paddle plate covers the outlet port for the pump 23 and the curved plate covers the inlet port for the pump 22. Since the valve is oscillated in timed relation with the reciprocation of the pumps, each pump receives a char-ge of concrete through its open inlet port 19 and through its intake port 25 while its outlet port 21 is closed by the paddle plate 37 and then pumps the charge through its outlet port and into the delivery pipe while its inlet port is closed by the curved plate 36.

To reciprocate the concrete pump pistons 26, the actuator pumps 29 and 30 (FIG. 9) conduct oil under pressure from the pressure pump 31 to the tubular piston rods 28 and coact with the latter to force the concrete pistons forwardly under the influence of the fluid pressure. In addition, the two actuator pumps are interconnected by a closed hydraulic circuit in such a manner that forward movement of one concrete piston is operable to produce a corresponding but opposite movement of the other piston. For these purposes, each actuator pump comprises a stationary cylindrical piston 73 fitting tightly but slidably within the -bore of the piston rod and forming one end of a fluid-tight chamber 74, the remainder of the charnber being defined 'by the closed end 27 and the interior walls of the piston rod. Extending rearwardly from each actuator piston 73 is an elongated tube 75 rigidly fastened at its rear end to a stationary frame member and dening a longitudinal passage 76 which communicates with the oil pump 31 and extends through the actuator piston 73 into the chamber 74. As oil under pressure is forced through the passage and into the charnber, it reacts against the actuator piston 73 thereby causing the piston rod 28 to slide forwardly on the actuator piston and forcing the concrete piston 26 forwardly or to the right as viewed in FIG. 3.

The closed hydraulic circuit for retracting the concrete pump pistons 26 is formed by an outer tube or sleeve 77 disposed coaxially with the inner tube 76 of each

actuator pump

29 and 30 and spaced from the inner tube to define a longitudinal passage 7S extending between the sleeve and the tube. At its rearward end, the sleeve 77 is fastened to a gland 79 on the frame 12 while the forward end of the sleeve is telescoped into the bore in the piston rod 28v and Vjoined to the actuator piston 73. The inner walls of the piston rod and the outer walls of the sleeve for-m a chamber which is closed at its forward end by the actuator piston 73 and at its rearward end by a flanged bushing 81 threaded into the end of the piston rod and slid-able on the sleeve 77. The chamber 80 communicates with the passage 78 by means of ports 82 formed in the forward end of the sleeve near the actuator piston 73, and the passages 78 of each actuator pump communicate with each other through ya cross pipe 83 which interconnects ports 84 (FIG. 4) fonmed in each gland and in the rearward end of each sleeve. With this arrangement, the chambers 80l and passages 78 of the two actuator pumps, in conjunction with the cross pipe 83, form a closed hydraulic circuit between the pumps and this circuit is always filled with a constant volume of oil. Accordingly, as one of the piston rods 28 slides forwardly under the influence of the pressure fluid admitted through the passage 76, the flanged Ibushing 81 moves toward the actuator piston 73 thereby reducing the size of the associated chamber 80 and forcing the oil therein through the ports 82 and into the passage 78. From this passage, the oil flows into the cross pipe 83 and then into the passage 78 and the chamber 80 of the other actuator pump. As the fluid enters the opposite chamber 80, it exerts pressure between the rear side of the actuator piston 73 and the flanged bushing 81 thereby to slide the piston rod 28 rearwardly on the actuator piston 73 and to retract the concrete piston 26. There is no flow of oil in the closed circuit except between two actuator pumps and the direction of this flow periodically reverses to retract alternate concrete pistons 26.

For reciprocating the concrete pump pistons 26 in unison, but in opposite directions and for oscillating the valve 35 in timed relation with reciprocation of the pump pistons, oil from the pressure pump is introduced alternately to the passages 76 of the actuator pumps 29 and 30 and also to the

cylinders

62 and 63 of the oscillating mechanism 59 through a 4-way valve 85 which is controlled automatically by the motion of the concrete pumps. As shown in FIG. 9, the pressure pump 31 draws oil from the reservoir 32 through a pipe `86 and pumps the same into a body 87 of the valve 85 through a feed pine 8S. In accordance with the position of a spool 89 slidably mounted in the valve body, the `oil flows from the body into one of a -pair of pipes 90 and 91 connecting the Ibody with the passages 76 for the actuator pumps 29 and 30. When the spool is positioned as shown in FIG. 9, fluid is admitted from the pressure pump 31 into the pipe 90 and then into the passage 76 and the chamber 74 of the actuator 29 to force the piston 26 of concrete pump 22 forwardly. The piston of the other concrete pump 23 simultaneously retracts because of the closed hydraulic circuit between the pumps, and as` a result, yoil in the chamber 74 of the actuator pump 3f) exhausts through the passage 76 and the pipe 91 into the valve body, and then to the reservoir through a return line 92 connected between the valve body and the reservoir. In addition, oil flows from the pipe 90 through a branch line 93 connected to the valve oscillating cylinder 62 to shift the piston rod 64 to the left (FIG. 7) thereby positioning the concrete valve 35 in accordance with the condition of the concrete pumps. Oil from the cylinder 6-1 exhausts through a -branch line 94 connected to the pipe 91. Because less power is required to oscillate the valve 35 than to reciprocate the pumps, the valve will shift to its proper position just before the piston 26 begins its forward stroke.

As the piston 26 of the con-crete pump 22 reaches the end of its forward stroke, the flange on the bushing 81 engages the end of a lever 95 (FIG. 9) to rotate the lever counterclockwise about the pin on the frame. The lever is connected to the valve spool 89 by a link 97 which shifts the spool forwardly as the lever rotates thereby to establish fluid communication between the feed pipe 88 and the lpipe 91 leading to the passage 76 of the .actuator pump 30. Accordingly, the piston 26 of the concrete pump 23 then is forced forwardly and the piston of the concrete pump 22 retracts with the fiuid from the chamber 74 exhausting through the pipe 90 into the valve body 87, and then to the reservoir 32 through a return pipe 98 connecting the valve body with the return -pipe 92. At the same time, oil is supplied to the branch line 94 and the cylinder 63 thereby shifting the piston rod 64 to the right (FIG. 7) and reversing the position of the concrete valve 35 just before the piston 26 of the pump 23 begins its forward stroke. The valve spool 89 is returned to the position shown in FIG. 9 when the piston of the concrete pump 23: reaches the end of its forward stroke and the flange on the associated bushing 81 engages the opposite end of the lever 95 to rotate the latter clockwise. Accordingly, the valve spool is shifted between its two positions each time one of the concrete pistons reaches the end of its forward stroke thus causing oil to be supplied first to one actuator pump and then to the other and simultaneously causing oil to be supplied to alternate cylinders of the oscillating `mechanism 59. Since the reversal of the pumping action and of the valve position is controlled by the motion of the pumps themselves, the

flow of concrete to the delivery pipe is substantially continuous throughout the pumping operation.

The present invention also contemplates novel means enab-ling quick yand easy removal of the concrete pistons 26 from the piston rods 28 when it is necessary to clean or replace the pistons. In this instance, these means com- :prise a male connector 100 (FIG. 3) on each piston rod and a female connector 101 (FIG. 5) on each piston, the two connectors interfitting to restrict movement of the piston axially of the rod while permitting movement of the piston radially of the rod for uncoupling the piston from the rod. As shown in FIG. 3, the male connector 100 is a short cylindrical shank 102 projecting forwardly from the closed end 27 of the piston rod and formed with an annular button or head 103 on its forward end. The forward end ofthe rod and the rear face of the head form' a pair of axially spaced shoulders which, in conjunction with the shank 102, define an annular groove 104 between the button and the end of the rod. The female connector 101 (FIG. 66) comprises a flat disk 104a at the rear end of the piston, and a semi-circular lip S projecting axially from the disk and [formed at its free end with an inturned radial coll-ar 106. A pair of toes 107 depending from the transverse ends or legs of the collar act with the latter to define a downwardly opening U-shaped notch 108 which has a transverse width slightly greater than the diameter of the shank 102 of the male connector.

As shown most clearly in FIGS. 3 and 9, the collar i106 on the piston 26 fits within the groove 104 formed by the male connector with the lip 10S overlying the upper sur face of the head 103 and with the toes 107 straddling the shank 102. Opposite faces of the collar and the toes abut against the shoulders formed by the bead and the end of the piston rod to restrict axial movement of the piston while the Ushaped notch 108 permits uncoupling of the ro'd and the piston simply by lifting the latter in a radial direction.

Herein, the pistons 26 are composed of #a exible material such as rubber so as to maintain a tight fit within the cylinders 24. Specifically, each piston comprises a pair off rubber sleeves 135 (FIG. 9) fitted over the shank 136 of a bolt threaded into the `disk 104s. The sleeves are sandwiched between the disk `and an enlarged head 137 integral with the shank and are formed with front and rear outwardly turned scraping edges 138. As a result of this arrangement, any concrete that might possibly work past the forward scraping edge on the forward stroke of the .pistons will be carried rearwardly from the cylinders by the rear scraping edge on the return stroke. The sleeves may be removed for replacement purposes merely by unthreading the bolt from the disk and slipping the sleeves ott of the shank.

The frame 12 and the cylinders 24 are arranged to provide convenient access to the pistons 26 thus permitting uncoupling of the pistons and the rods 28 without having to dismantle any of the other pumping elements. For this purpose, a box-like sub-frame 109 (-FIG. 3) is supported on the main frame 112 and has an open upper side and a fore-and-aft dimension greater than the length of the pistons. The cylinders 24 are connected to the front wall of the sub-frame and open into the interior thereof, while the piston rods 28 are slidably mounted in bushings 110 fastened to the rear wall of the sub-'frame and project forwardly into the cylinders. When the

pumps

22 and 23 are operating, the normal stroke of the piston rods is such that the pistons are always confined within the cylinders, as shown in full lines in FIG. 3, and thus the pistons remain connected to the rods. When 'a piston change is necessary however, the piston rods may be slid manually and rearwardly to pull the pistons out of the cylinders and into the opening defined Iby the sub-frame as shown in dotted lines in FIG. 3. The pistons then are fully exposed and may be lifted olf of the rods and replaced with pistons fitted with new rubber sleeves 135.

When 'the

pumps

22 and 23 Iare operating, it is desirable to have the frame 12 as stable as possible to prevent movement of the frame under the influence of the reaction forces produced by the reciprocation of the pump pistons 26. In the past, it has been the practice to block each side of the wheels 13 or to jack up the tframe and place blocks thereunder to keep the frame stable, these operations requiring a considerable amount of set-up and teardown time. In another of its aspects, the present invention contemplates mounting the frame andthe wheels for relative vertical movement under the control of hydraulic operators 115 whereby the frame may be lowered to rest firmly on the ground or other supporting surface when the pumps are operating simply by actuating the hydraulic operators.

For this purpose, each bar 15 mounting the wheels is pivotally connected at 116 to the lower end of an upright post 117 (FIGS. 1 and 2) which is slidably received in a vertical channel 118 fast on the side of the frame. To restrain movement of the bars about the pivot 116, semi-eliptical springs 119 are compressed 'between the upper side of the bars and flanges 120 projecting outwardly from the posts 117. The piston rods 121 of the hydraulic operators are fastened to the upper ends of the posts 117 and slide in cylinders 122 rigid with the frame. In FIG. 2, the trailer 11 is shown in transport position with the frame 12 spaced above the ground `and with the posts 117 located in the lower ends of the channels 118. In this position, the operators are energized by oil admitted into the cylinders 122 through a line 125 (FIG. 9) communicating with the pressure pump 31 and controlled by a valve 126. To lower the frame to operating position, it is necessary only to open the valve 126 and a valve 127 ina return line 128 thereby releasing the oil in the cylinders and allowing the frame to slide downwardly on the posts 117 and relative to the wheels. As a result, Ithe frame may be lowered in a matter of seconds to rest directly on the ground or on planks placed under the frame and thus will be in a very stable |condition during operation of the pumps.

I claim as my invention:

1. In a machine for pumping fluent concrete through a delivery pipe, Ithe combination of, an elongated frame, a hopper on said frame for receiving a quantity of concrete to be pumped and having an open lower end, a valve housing disposed beneath said hopper and including opposed laterally facing side walls, an upright partition located within said housing between said Walls and dividing the housing into first and second laterally spaced delivery passages extending downwardly from said hopper, the upper ends of said passages defining side-by-side upwardly opening inlet ports communicating with the open end of Said hopper for admitting a gravity fiow of concrete from the hopper into the passages, said passages having laterally spaced side-by-side outlet ports opening out of said housing below said inlet ports and .adapted to communicate with the delivery pipe, first and second reciprocating pumps on said frame and communicating with said passages through side-by-side intake ports opening into said housing below said inlet ports and being alined with said outlet ports, means for reciprocating said pumps in unison but in opposite directions whereby one pump draws concrete from its respective passage through its intake port while the other is pumping concrete through its outlet port, a valve member mounted in said housing for back and forth oscillation between first and second angularly spaced positions about a predetermined axis extending through said partition, said valve having :an upwardly facing plate thereon formed with upper and lower surfaces arcuately curved about said axis and swingable during such oscillation along an arcuate path extending between said side walls and over said partition, said plate overlying and closing said first inlet port in said first valve position and overlying and closing said second inlet port in said second valve position thereby alternately opening and closing said inlet ports to control the fiow of concrete to said passages, said valve also having a second plate disposed in a plane perpendicular to said axis and swingable during such oscillation in a path extending between said side walls and across both of said outlet ports, said second plate overlying and closing said second outlet port in said first valve position land overlying and closing said first outlet port in said second valve position, and mechanism for oscillating said valve between said positions in timed relation with the reciprocation of said pumps whereby each pump receives concrete through its respective inlet port while its outlet port is closed and then pumps the concrete through its outlet port while its inlet port is closed.

2. In a concrete pumping apparatus, the combination of, a frame, a `hopper on said frame for receiving a quantity of wet concrete to be pumped and having an open lower end, a housing disposed beneath said hopper and having first and second delivery passages extending downwardly from laterally spaced side-by-side inlet ports communicating with said open end to receive concrete from said hopper, said passages having laterally spaced side-by-side outlet ponts opening out of said housing below said inlet ports, first and second reciprocating pumps for drawing concrete from said hopper lthrough said passages and pumping the concrete through said outlet ports, each pump having a cylinder opening into the respective passage, and a valve member mounted in said housing for back and forth oscillation about a predetermined axis between first and second angularly spaced positions, said valve having an upwardly facing closure thereon swingable during such oscillation along an arcuate path extending `across said inlet ports and overlying and closing said first inlet port in said first valve position and overlying and closing said second inlet port in said second valve position thereby alternately opening and closing the inlet ports to control the flow of concrete thereto, said valve also having a second closure disposed in a plane perpendicular to said axis and swingable during such oscillation along a path extending across both of said outlet ports, said second closure overlying and closing said second outlet port in said first valve position and overlying and closing said first routlet port in said second valve position, and means for reciprocating said pumps and oscillating said valve in timed relation to hold said valve in said first position While said first pump is pumping and said second pump is drawing concrete from said hopper,

and t-o hold the valve in said second position when the condition of the pumps is reversed.

3. Concrete pumping apparatus as defined in claim 2 in which said housing comprises opposed longitudinal side walls and laterally extending end walls interconnecting said side walls, said delivery passages being formed by said walls and by an upright partition disposed between said side walls and extending longitudinally from one end wall toward the other end wall.

4. Concrete pumping apparatus as defined in claim 3 in which said valve member oscillates about an axis extending through said partition, and said first closure comprises an upwardly facing plate having upper and lower surfaces curved arcuately about said axis, said plate oscillating in a path extending between said side Walls with the lower surface of said plate passing over the upper end of said partition during such oscillation.

5. Concrete pumping apparatus as defined in claim 4 in which said plate extends tangentially to alternate side walls in alternate valve positions.

6. Concrete pumping apparatus `as defined in claim 4 in which said one end wall has an arcuately curved groove therein and said plate has Ia similarly cur-ved edge riding in said groove.

7. Concrete pumping apparatus as defined in claim 3 in which said partition terminates short of said other end wall to define 4a vertically extending slot between the other wall and the opposing face of the partition, and said second closure comprises a plate disposed in an upright plane and swingable through said slot during oscillation of said valve member.

8. Concrete pumping apparatus as defined in claim 7 in which said housing is formed with an arcuately curved bottom interior surface, and said second closure plate is formed with a similarly `curved lower end riding closely adjacent to said surface during oscillation of said valve member.

9. Concrete pumping apparatus Vas defined in claim 3 in which said cylinders communicate wit-h said pass-ages through laterally spaced side-by-side intake ports formed through said one end wall, said outlet ports being formed through the other of said end walls and being alined with said intake ports to establish a substantially straight flow path from said cylinders to said outlet ports.

10. Concrete pumping apparatus as defined in claim 3 further including a siamese pipe section communicating with said outlet ports, and means lhingedly connecting said section to said housing.

11. Concrete pumping apparatus as defined in claim 2 further including a piston and a pis-ton rod mounted for l'eciprocation in each of said cylinders, a male coupling on one end of said rod and including an annular shoulder axially spaced from said end to define an annular groove between the shoulder and the end of the rod, and a female coupling on the end of said piston facing said rod and including a U-shaped collar fitting over said male coupling and within said groove and engaging said sh-oulder to restrict uncoupling movement of said piston axially of said rod While enabling uncoupling movement of the piston radially of the rod.

12. Concrete pumping apparatus as defined in claim 2 further including wheel assemblies on each side of said frame for supporting the latter, means mounting said frame on said wheel assemblies for up and down sliding between a transport position in which the frame is disposed above the level of a supporting surface and the weight of the frame is supported by said wheel assemblies, and an operating position in which the frame rests upon the supporting surface with substantially none of its weight carried by the wheel assemblies, and actuating mechanism connected between said wheel assemblies and said fname for raising the latter from said operating position to said transport position.

13. In a concrete pumping apparatus, the combination of, a housing having two upright flow passages disposed in laterally spaced side-by-side relation, two laterally spaced inlet por-ts opening into the upper ends of said passages in side-by-side relation, land two laterally spaced outlet ports opening into the lower portions of said passages in side-by-side relation; and a valve mounted in said housing for back and forth `oscillation about a predetermined axis between two angularly spaced positions, said valve having a first upwardly facing closure movable along an arcuate path across said inlet ports and alternately opening and closing the latter during such oscillation, said valve also having a closure disposed in a plane perpendicular to said axis and swingable back and forth in said plane during such oscillation to close the outlet port of each passage when the inlet port of the passage is open.

14. 'Concrete pumping apparatus as defined in claim 13 in which said valve comprises a hub and an upright plate projecting radially upwardly from said hub, said lirst clo- 12 sure comprising an yarcuate plate disposed perpendicular to said upright plate and having upper and lower surfaces curved c-oncentrically about said axis, and said second closure comprising a plate projecting radially downwardly from said hub and disposed in a plane perpendicular to said axis.

References Cited UNITED STATES PATENTS 2,519,002 8/1950 Stemen et al. 280-44 3,147,023 9/1964 Ragmo ZBO-43.23 3,181,469' 5/ 1965 Schumann 10S-49 3,298,322 1/ 1967 Sherrod 103-170 3,331,332 7/1967 Wennberg 103-170 ROBERT M. WALKER, Primary Examiner.