US2174089A - Mixing apparatus - Google Patents

Description

Sept. 26, 1939. c. s. JOHNSON.

MIXING APPARATUS Fi1ed Feb. 6, 1959 3 Sheets-Sheet 1 gizmles 6x76722601? m.M/%Mm Sept. 26, 1939.

C. S. JOHNSON MIXING APPARATUS Filed Feb. 6, 1959 3 Sheets-Sheet 2 C/zarles ddizizsoiz P 39- c. s. JOHNSON 2,174,089

MIXING APPARATUS Filed Feb; 6, 1959 s Shets-Sheet 3 MIN l 1 M 7 fig 7 V I! I 62 w l 82 fizz/6212227 C/zazieadJb/mson Patented Sept. 26, 1939 PATENT orrica MIXING APPARATUS Charles S. Johnson, Champaign, Ill., assignor to The O. S. Johnson 00.,

poration of Illinois .Champaign, 111., a cor- Application February 6, 1939, Serial No. 254,881 15 Claims. (Cl. 259-154)- The present invention relates to apparatus for,

preparing mixed concrete and is particularly applicable to so-called central mixing plants.

For an example of a form of central mixing plant heretofore available reference may be made to my prior Patent No. 2,109,534 issued March 1,

1938. Briefly stated, a central mixing plant ordinarily embodies a mixer or battery of mixers;

a group of elevated bins above the mixers and in which are stored the reserves of necessary con-,

stituents for the concrete mix, batching means for withdrawing predetermined quantities of the respective materials from the bins to form charges for the mixer or mixers, and a charging mechanism for chuting the batches of material to the mixers. Such plants find particular utility in the building of dams and the like in which enormous quantities of mixed concrete are required. Despite the large quantities of material which must be handled very rigorous control of quality must be observed. The ultimate strength of the concrete structure islargely governed by the uniformity with which the concrete in it meets the specified standards of mixing. Accordingly, a mixing plant must not only be capable of achieving a mix of specified quality but it must be capable of reproducing this mix time after time with extreme uniformity. k With the development of the art has come a de- 1 mand for improvements in control, better '00- ordinated operation of the elements of the plants and more general use of mixers of larger and larger individual capacity. Such demands have,

however, introduced many new problems because i of the volume of material which must be speedily and efliciently handled in each mixer charge. For example, in a small mixer it'is of comparatively little importance-in what order'or in what 40 charged into the mixer, but in a large mixer of relation, but in addition the mixer is likely to become clogged and even filled with set concrete if the materials are not charged in a particular manner.

accurately duplicated in each successive mix. Similarly, dust rising from a stream of material fed into a small mixer is little more than a nuisance, but with large capacity inixers its handling becomes a major problem. Accordingly, on gen- 6 eral object of the present invention is to provide an improved form of central mixing plant which is. especially adapted to meet the requirements imposed by the use of large capacity mixers and plants. It should be understood, however, that 10 the present invention, in some of its aspects, also finds utility as applied to mixing plants using smaller mixers: r

A more specific object of the invention is to provide a central mixing plant of such character 1 that a uniform and eflective distribution of dry cement is insured throughout the stream of other materials supplied in each mixer charge, even a when the charge is very large in total volume.

Another object of the invention is. to provide 20 ina concentric zone type of mixing plant, an improved water'batcher by means of which selected quantities of water may be quickly and effectually supplied to each mixer during its charging period.

Stillanother, and important, object of the in- 25 vention is to provide'in a mixer charging apparatus, a novel form of water batcher and charging mechanism of such character that the water is supplied not only in measured total quantities but at a controlled rate and in a desirable relacomplished and gumming or clogging of the mixer obviated, and whereby all mixers in a battery may .be similarly and coordinately charged.

' ply arrangement-for the batcher of Fig. 3.

Figs. 5 and 6 are respectively end and side elevations of the water batcher of Fig. 3. I

Fig. 6' is an enlarged detail'view of a portion of the waterbatch scale beam linkage.

Fig. lis aplan view of a water charging reservoir for the plan of Fig. 1.

scribed in head or spout l8, rotatable Fig. 9 is a vertical sectional view along the line 9-9 in Fig. 7.

General plant layout For purposes of exemplification the invention has been shown herein as embodied in a concentric zone type of central mixing plant. The general arrangement of (see Fig. 1) will be familiar to those skilled in the art and, accordingly, a brief identification will sufllce for the conventional elements of the combination. It will be appreciated that substitutions may be made of equivalent elements as desired, and that in some aspects the invention is applicable to entirely diflerent types of mixing plants in which, for example, a single mixer rather than a battery of mixers in other aspects the invention is applicable primarily only to plural mixer installations. Consequently, even though one particular embodiment of the invention has been shown and desome detail there is no intention to thereby limit the invention to such embodiment, but on the other hand the appended claims are intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention.

The general layout of elements in the mixing plant shown herein (Fig. 1) includes a series of bins l0 supported in elevated position by aframework ii. These bins aiIord segregated storage spaces for reserve supplies of the dry constituents of concrete mixes, including dry cement as well as so-called aggregates such as sand, gravel and rock or cobbles of various sizes. These materials are withdrawn through a suitable gravity flow chute system (not shown batchers l 2--il. A separate weigh batcher, is provided for each constituent of the final mixer charge, and may be of any suitable form such, for example, as that disclosed in my prior Patent No. 2,008,305 issued July 16, 1935. Desirably, the centrally located batcher I2 is used for the dry cement and as many additional batchers are provided as may be required for the number of different types of aggregates used. Alternatively a multiple material batcher may be used.

From the batchers the materials are chuted to a centrally located collector cone or supply hopper I! in which they intermingle and flow into a tumabout a vertical axis on a tripod I1, and driven by a suitable electric motor IS. The turnhead I. can be turned into charging relation with respect to any one of a battery of mixers which may, for example, be four in number .arranged at intervals of 90 about a central axis. Two such mixers l9-2l, are shown in Fig. 1. These mixers have been shown as being of the conventional front-charged frontdischarged type with openings 2i in their forward ends which are arranged to face inwardly toward the centerof a charging zone A, on the center line on which the turnhead It is located. These mixers are of the rotating type and are shiftable in the usual manner by air rams 20' from an upwardly tilted chart ng position, like that of the mixer is in Fig, 1, to a downwardly tilted discharging position, like that of the mixer 20 in Fig. 1. Whenin this discharge position the contents of the mixer falls into a centrally located discharge hopper 22, concentric with the charging zone A and which serves to direct the cement mix into a suitable receiver such as the parts for such a plant through a spout is used, although I in detail) into weigh into the collector cone II tributor head or cone ing a lower-end cone 33, through the medium of a suitable air ram aca conveyor or truck (not shown). A platform 23 serves to support the mixers "-40, the discharge hopper 22 and the turnhead tripod l1.

Water is supplied for each mixer charge from a novel form of water batcher, designated generally by the numeral 24, through the medium of awater charging mechanism 25 carried by the turnhead it, all as is hereinafter described in greater detail. For the present it'is sufllcient to note that the water is discharged from the charging mechanism 26 (see also Fig. 2) through which it flows into the open mouth 2| of the mixer which is being charged.

Mixer charcinq mechanism.

To accomplish a large degree of premixing and coordinated material charging, a novel form of charging mechanism has been employed. By premixing is meant not only the mixing of the dry constituents of each mixer charge prior to the time it enters the mixers ill-20 but also the feeding of all constituents at controlled rates relative to each other so that the ingredients of each increment of the charge are in substantially the same proportions to each other as in the final mix. This is an especially important consideration when charging large capacity mixers which receive a charge oi say, three or more cubic yards.

Such importance will be apparent when I it is considered that the output of the plant is largely governed by the time required by each mixer to complete the necessary mixing of the chafrge constituents in it. If the constituents of the charge should be fed serially rather than simultaneously into a large mixer a comparatively .long time would be required in order to break up the segregated masses of each material and mix them thoroughly throughout the entire mass of the charge. By charging the constituents into the mixer itself substantially simultaneously and at controlled rates with respect to each other, however, each of the constituents can be so thoroughly disseminated throughout the entire mass that the mixing time required in the mixer itself is materially reduced. In the present instance the charging-mechanism is so arranged that the ma- 1 mixed condition. V

Regulation of the now of aggregates from each of the individual batchers ll-ll is accomplished in the present arrangement. After the batches are complete in the batchers [3-H they are dumped by fully opening the respective bottom discharge gates I. through the'medium of suitable air ram actuator mechanisms. which may be operated by means of either an automatic or manual s p rvis ry control system (not shown). From these gates the aggregates c are chuted through sharply inclined chutes II having control valves or gates 20 interposed therein (Fig. 2). These gates 20 may be shifted vertically by'manual operating handles 2 so as to regulate with nicety the rate of flow of the corresponding stream of aggregates. In this way the rates of flow for the respective aggregates can be regulated'to give any desired relation of one with respect to the others.

In order that the dry cement cshall be diffused throughout all of the multiple streams of aggregates entering the collector cone II, a dia- 32 has been provided (Fig. The cement butcher i2 is dumped by openshaped valve head or gate tuator 84. 'Ihereupon the dry cementc falls by gravity through a cylindrical conduit 35 having funnel shaped upper and lower ends 35 and 35 The lower funnel shaped and 35 is generally complemental in contour with the diflusing cone 32 and is arranged in spaced relation above the same. flowing downwardly through the conduit 35 strikes the opposed face of the cone 32 and is fanned out over the streams of aggregates a entering the'collector cone l and is thereby thor-= oughly intermingled with the same.

From the foregoing it will be seen that a substantial degree of premixing of the batch constituents is accomplished. In other words the streams of aggregates a flow into the collector cone l5 simultaneously and at controlled. rates, rather than in sequence, and most important, the dry cement c is efiectually difiused through these converging streams of aggregates.

Dust-proofing of the equipment is also a serious problem in charging large capacity mixers, and the improved charging mechanism' herein shown is particularly adapted to meet this problem. Upon reference to Fig. 2 it will'be seen that the top of the collector cone I5 is closed by a horizontalpartition or floor 36. The aggregate control gates 28 cooperate with the chutes 21 to form substantially closed connections from the batch ers l3|4 to the top of the collector cone. There is some clearance between the upper ends of the chutes 21 and the discharge spouts on the lower ends of the batchers l3l4 but these spouts extend a substantial distance within the chutes so that in view of the heavy character of the material the connections are substantially dust tight. In the case of the cement batcher I2, a dust tight connection is formed by the lower end of the batcher and theupper end of. the conduit 35. For this purpose and also over an annularcollar38 registering with the upper end 35 of the conduit 35. Suitable clamping rings or the like (not shown) may, of course, be utilized to secure the conduit 31 in position. In this way the escape of dust'and finely divided material is prevented at the top of the collector cone l5.

,To seal the connection between the turnhead a flexible cylindrical casing '31 is telescoped over the lower end of the batcher Consequently the stream of dry cement into'the mixers through the IS and any one of the mixers l920 which it is charging, a special dust-proof connection is provided. In the-particular arrangement shown an annular sheet metal collar or extension section 39 (Fig. 1) is telescoped over the lower end of the turnhead chute or spout l6. This section is carried by a yoke 43 which embraces the top of it and is pivoted at 43 ona bracket 44 fast on the turnhead I6. 4 This extension section 39 carries a flange 4|!- complemental to a flange 4| on the mouth of the mixer so that when the section 39 is swung toward the mixer the flanges 404l are pressed against each other and a dust tight connection is completed from the spout to the mixer. Similarly, when the section 39 is retracted the mixer is freed for tilting movement without interference by the extension section. A linkage mechanism, designated generally by the numeral 42, serves to actuate 4 linkage 42 includes a bell crank 42', pivoted at 42' on the turnhead structure, and adapted to be oscillated by an air ram 42. The outer end of the bellcrank is pivoted to a collar 42 which is oscillatable between stops on a pin 42. This pin 42 is in turn pivotally connected to the yoke 43.= A compression spring 42 is interposed between the collar 42 and the head. at the lower.

the extension section. This end of the pm 42. Accordingly, the spring completes a yieldable connection from the ram actuated bell crank 42 to the yoke 43 so that the extension section 39 is yieldably pressed against the mixer mouth.

(in a clockwise direction as viewed in Fig. 1) the collar 42' abuts against form a positive connection for retracting the extension section.

In order to prevent choking of the mixer and chute structure as the aggregates are charged mechanism describedabove, an exhaust fan must be sufllciently limited to permit a free escape of the displaced air from the mixer and without any jamming or clogging at the. mixer entry throat.

Charging cycle Speedy and uninterrupted mixeroperation is,

in large measure, dependent upon proper reguladust-tight charging tion of the. flow cycles for'the constituent ele- The most critical of all is the water charge in coordination with the stituents. on in a cycle which includes the following steps:

1. Charging of the water started first and carried on for a sufilcient interval before the dry constituents enter the mixer so that a pool is formed in the bottom of the mixer.

2. Large cobbles or rock started next and before the finely divided constituents such as sand and cement start to enter the mixer.

3., Thereafter and during the remaining major portionof the charging cycle all of the materials rates proportioned so that the flow of the dry materials will terminatesubstantially simultaneously.

of from three to five seconds.

. By instituting the charging of the water before have to be cleared away by laborious drilling and bles which are first charged into it before and the scale levers 5|v are 55, the levers during the regular mixing operation. During the main part of the charging operation the water is charged at a rate proportionate to the flow of the dry-constituents so that it is mixed with them in the proper proportions as they enter the bottom of the mixer body. Finally, by continuing the water charge for a short interval after the dry constituents-have been charged into the mixer, the mouth of the mixer is secured so as to prevent any gumming which would interfere with its free discharge after the mixing is complete. As will hereinafter appear, and charging mechanisms 24 and 25 are particularly designed to effectuate such a charging cycle as that described above.

Water batcher A minimization of over-all operating time, and especially in a concentric zone type of mixing plant embodying a plurality of mixers, is achieved by the utilization of the novel form of water batcher herein disclosed. This batcher is arranged concentrically with the axis of the charg-.

ing zone A, and in the. particularconstruction shown (Fig. 1) embodies a scale hung annular tank 50 encircling the collector cone l5. By thus locating the water batcher closely adjacent the charging zone, water can be quickly charged from it into a selected mixer without the time interval required in prior installations such asthat shown in my Patent Ito-2,109,534 referred to above and in which the water batcher is remote from the mixers and the water has to flow through a long conduit before reaching the charging zone (see conduits 2i and 22 in Fig. 1 Elimination of any delay in, starting the water charging is particularly im-- of said patent).

portant in carrying out the charging cycle set forth above, or a series of such cycles, and in which the water must hit the mixer in advance of any of the dry constituents of the mix.

Any suitable proportioning arrangement may be provided for filling the water batcher tank 50. The arrangement forthis purpose herein shown embodies an automatic weighing mechanism adapted to control the flow of water to the tank so that a predetermined batch of water is accumulated in the tank. In particular it includes .a pair of horizontal scale levers 5| (Fig. 3) 0011? nected to the tank 50 by rocker arms 52. These rocker arms are pivoted intermediate their'ends (Fig. 6) at '53 on the the stationary collector cone l5 and are journaled at their outer ends on the scale levers 5|, and are pivoted at their inner ends to the tank 50, as indicated at 54. Accordingly, as water is flowed into the batcher tank 50 the rocker arms 52 turn in a counterclockwise direction (as viewed in Fig. 6) so that elevated as the tank 50 descends, due to its increasing weight. g

The scale levers 5| are interconnected by a. pair of opposedlevers 55 (Fig. 3), which are rigidly connected to the levers 5i, and are gath-' J ered by a shackle 55 (Fig. 6). From the shackle 55 are connected to a scale beam 51 (Fig. 5) by a suitable system of levers 58, 5!, 55 and ii (Figs. 5 and anism associated with the scale beam 51 is substantially like that shown for the batchers illustrated in my Patent No. 2,109,534 referred to above and, consequently, a detailed description is not believed to be necessary. In general, any one the water A batching .Thereafter a minor or a the mixer is assured.

6). Thebalancing mech of a series of weighing beams 52-55" may be placed in operative relation with the scale beam 51 by releasing its associated beam lifter 56. The several weighing beams 82-45 areset for predetermined different weights and the operator need only render the selected one operative in orderto weigh out a corresponding batch of water. After one of the weighing beams 62-65 has been selected and placed in operative relation with the scale beam 51 the latter serves to actuate a pair of mercury switches 51-48 for automatically terminating the filling of thebatcher tank 55 when the water batch is complete. A pointer 69 cooperates with a graduated scale 10 in order to give the operator a visual check of the operation of the automatic weighing mechanism.

Water is supplied to the batcher tank 50 (Fig. 4) from a suitable water supply pipe 1|. flow of water from this pipe to the batcher tank is controlled by a pair of parallel connected poppet valves 12 and 12. ing operation both of the valves 12 and 13 are opened by their associated power actuating mechanisms 14 and 15, respectively. Thereupon, water flows from the supply pipe 1! into the tank 50 through the main valve 12 and a supply The To initiate the water batchconduit 15 loosely telescoped within a cylindrical plete the weigh beam 51 is tilted sufflciently that top of the tank. In

the switch 81 is closed (Fig. 5) to thereby cause the main valve actuator 14 to close the main valve 12 and cut oil the major feed of water. dribble feed continues through the auxiliary or by-pass valve 13 until the batch is finally complete, at which time the weigh beam 51 is tilted the other switch 68 so as to cause the valve actuator 15 to close the minor feed valve 13. By utilizing such a major and minor feed arrangement, overrunning of the batch is effectually prevented. The rate of fiow of water through each of the valves 12 and screws 80 and 8|, respectively.

batcher tank 50 to the respective mixers, the, tank 50 is provided with a series of outlets 82 (Figs. 2 and 3) corresponding in number and location to the several mixers "-20. During the filling of the batcher tank, while the automatic weighing operation described above is in progress, all of these outlets 8 2 are closed by their respective solenoid actuated valves 52. Then, when the mixer charging cycle is instituted all four of the valves 53 are opened simultaneously so that the water may flow rapidly. into the charging mechanism 25. Irrespective of the location of the turnhead litand of the charging mechanism 25 which it carries, one of the batcher outlets 52 will, however, always be located directly in registry withthe water charging spout 26 so that a strong and undelayed initial flow of water into To expedite the final draining of the batcher tank 50, its bottom is inclined from high points 50', intermediate the outlets 82, toward such outlets (Figs. 5 and 6).

- Water. charging mechanism water 13 can be regulated by suit-' able adjustment means actuated by adjusting from the pipe 1| into still further andcloses it serves to direct the water from the batcher tank 58 into any irrespective of the rotational position of the turnhead IS, the reservoir 84 is made with an open top and into which the spouts 82 of the The bottom wall its outlet spout so that all' of the water recharged, a flow ceived within the reservoir 84 will fiow'by gravity to the outlet spout and thence into the mixer which is being charged.

To minimize, in so far as possible, the time inarranged so that one of them directly above the water charging spout 26 when the latter is in registry with one of the mixers. In other words, with four mixers, four of the outlet spouts 82 are provided (see Fig. 3) and located just above the position occupied by the charging spout 26 when the latter is in registry with correwill always be sponding ones of the mixers. Consequently, when.

the water batcher valves 83 flows directly downward, and preciable loss of time, spout 26 and is. directed without any apinto the water charging by it into the interior of for the aggregate batchers |3l4, it is apparent that the water will reach the mixer before any of the dry constituents of the mix even though all of the batcher gates be opened simultaneously,

thus insuring that the apparatus will eflectually carry out the first step in the preferred cycle of charging outlined above. Similarly in the second step of the cycle, before the sand and other more finely divided aggregates since the cobbles are heavier and fall faster to start their flow. Generally stated then, the apparatus is thus capable of carrying out the cycle described even without the necessity of providing a timing mechanism for sequential actuation of the batcher gates.

At this point it should be noted that the outlet of the water charging spout 26 is preferably directed laterally (Fig. 7) so that the water enter ing the mixer is correspondingly directed laterally as well as downwardly to aid in mixing the water with the dry materials and also to aid in securing the mixer walls.

To regulate the fi owoi water so that a portion of it will be held back and not fed into the mixer until after all of the dry constituents have been regulating arrangement is provided inthe reservoir 84. For this purpose a transverse partition 85 (Figs. 7-9) is provided in about a horizontal axis passing through the spout selected one of the mixers l8- 20 which is to be charged and second, it feeds the cobbles reach the mixer for from three to five next mixer.

s to reach the spout 26. Consequently, the discharge of the water in this portion of the reservoir can be prolonged by thesetting of the regulating' gate 81 on the orifice 88 so that the time of the water feed will exceed that of the dry constituents of' the mix as set forth in the preferred charging cycle previously described.

Brief rsum of operation are filled and have automatically weighed out previously noted. Assum-- of the respective materials the aggregate batcher discharge gates 38 (Fig.

cement batcher discharge gate 33 will also be closed, as are the discharge valves 83 on the water batcher tank 58. Also the turnhead I6 is assumed to be located with itsoutlet in registry with an uptilted empty mixer.

To initiate the charging cycle with the parts arranged as described above, the water batcher outlet valves 88 are opened and substantially simultaneously the other and 33 are also opened. 'I'hereupon water flows batcher discharge gates through all of'the outlet spouts 82 of the water batcher tank "into the water charging mechahism reservoir 84. Furthermore, water flows directly from one of the spouts 82 into the charging spout 26 through which it spurts into the interior of the mixer which is being charged. Since the water batcher is located closer to the mixer than are the other batchers the water enters themixer selected rates of flow for the streams of various egates. Into these converging streams of aggregates dry cement is distributed by the cone 32 so that it is thoroughly disseminated throughout themass of aggregates before they enter the mixer. During this charging period the flow of water continues from the reservoir 84 and thence through the spout 26 I into the mixer.

The exhaust fan is in operation throughout the mixing cycle so that the air displaced in the mixer leaves the charging chute system through the conduit 46 as does all of the loose dust and dirt rising from the streams of aggregates entering the mixer. In view of the dust-proof connections heretofore described little or no dustescapes about the mixing plant.

After the charging of the aggregates and cement is complete the water charging is prolonged seconds by the fiow of water which has been trapped behind the reservoir partition 85 and must escape through-the orifice 88 in order to reach the mixer. The water charged into the mixer in this final periodserves to wash the throat of the mixer and prevent summing or clogging at this point.

After one of the mixers has been completely charged,as described above, the toggle mechanism 42 is actuated to retract the spout extension section 88 and the turnhead I8 is swung through .an are "or 90 to bring it into registry with the The a gregate, cement and water batchers are this refillin refilled, and upon the completion of operation the same charging cycle the batcher tank 50 into that its contents are of charging even large mixers with a high degree of rapidity while minimizing the over-all time required for mixing. In fact with the apparatus shown, even mixers of four cubic yards capacity can be charged in as little as twelve seconds while still regulating the charging to obtain the preferred cycle set iorthc I claim as my invention:

1. A central mixing plant comprising, in combination, a dry material batching means for accumulating predetermined batches of dry materials, a mixer located below said batching means, said mixer embodying a container adapted to receive and retain a quantity of material while mixing the same, meansior directing dry ma-.

1 terials by gravity flow from said batching means to said mixer, a water batcher, means for flowing water by gravity from said water batcher to said mixer, and means for simultaneously discharging all of said batcherasaid water batcher being located adjacent to and above said mixer but at a substantial distance below said dry material batcher so that upon a simultaneous discharge of all of said batchers the water will reach the mixer in advance of the dry materials due to the shorter path which it traverses.

i -2. A central mixing plant comprising, in combination, a plurality of mixers arranged about a central charging zone with charging opemngs therein facing inwardly toward said zone, each of said mixers embodying a container adapted to receive andretain a quantity 0! material while mixing the same, a collector cone located above said zone substantially upon its line, a turnhead chute pivotal about said center line i'or chuting material by gravity flow from said collector cone into the charging opening of any selected one of said mixers, an annular water batcher tank encircling said collector cone, means carried by said turnhead chute for directing water discharged by gravity flow into it from said tank into the mixer with which-said turnhead chute is in'registry, a plurality of dry material batchers located a substantial distance above said .cone for feeding predetermined batches of ,material by gravityilow into the same, and means ior simultaneously discharging all of said batchers, whereby. upon the simultaneous discharge of both said dry material and water batchers the water, will reach the mixers'in advance of the dry materials due to the shorter path which it traverses.

,3. Ina mixing plant the combination of a mixer embodying a container adapted to receive and retain a quantity or material while mixing the same, means for feeding to said mixer a stream of dry'materials of predetermined total quantity to charge the same, means ior segregating a batch of water of predetermined amount, means for charging the water into the mixer in a stream which reaches the mixer inadvance oi the stream of dry material upon a substantially simultaneous and water charging means, and means for simultaneously discharging all of said batchers.

4. In a mixing plant the combination of a mixer embodying a container adapted to receive and.

retain a quantity or material while mixing the same, means for feeding to said mixer a tioned to receive at least a portion of the water tank and positioned to receive at least a portion stricting the flow vertical center of said 'dry material stantially simultaneous operation 01! said dry ma- 5 terial and water charging means in a stream which reaches the mixer in advance of the stream oi. dry material and which is prolonged by a selected variable interval of time beyond that required by the dry material feed, and means for simultaneously discharging all of said batchers.

5. In a mixing plant the combination of a water batcher including a tank having a valved outlet and adapted to contain a batch of water, a reservoir located below said batcher tank and posidischarged from said outlet, said reservoir having an outlet irom which water may be directed to a mixer, and means for directing the main portion of the water in a major stream from the reservoir into a mixer and for automatically and variably restricting the flow of the remaining minor portion of the water in said reservoir through said outlet thereof to prolong by a selected amount the time required for draining the same into'the mixer.

6. 'In a mixing plant the combination of a water batcher including a tank having a valved outlet and adapted to contain a batchof water, anannular reservoir located below said batcher or the water discharged from said outlet, said reservoir having an outlet from which water may be directed to a mixer, the bottom of said annular reservoir beingdnclined toward said outlet on each side or a transverse center line passing through said outlet, and means for. variably reof water to said reservoir outlet from a point adjacent one side thereof to prolong by a selected amount the time required for emptying the same into the mixer.

I 7. In a mixing plant the combination of a water batcher including a tank having a valved outlet and adapted to contain a batch of water, an annular reservoir located below said batcher tank and positioned to receive at least a portion or the water discharged from said outlet, said reservoir having an outlet from which water may be directed to a mixer, the bottom of said annular reservoir being inclined toward said outlet on each side of a transverse center line passing through said outlet, a transverse partition in said reservoirat one sideoi said outlet and adjacent the same, said partition having an aperture'thereln, and means controlling said aperture for variably restricting the flow of water to said reservoir. outlet to prolong by a selected amount the time re- 1 1 points about the periphery of said chatt g zone, a water batcher tank fashioned to embrace said hopper and extend substantially about thesame,

and means including a plurality of outlets for said batcher tank corresponding in number to the one of said outlets ll.

number or mixers and with located substantially in alinement with each of said mixers for charging water substantially directly from said bank into anyselected one or said mixers.

10. In a mixing plant, the combination of an aggregate collecting hopper located above a charging zone, a plurality of mixers disposed at 'spaced' points about the periphery of said charging zone, a. water supply means including a tank mounted closely adjacent said hopper, and means including a plurality of outlets for said tank corresponding in number to the number of mixers and with one of said outlets located substantially in alinement with each of said mixers for charging water substantially directly from said tank into any selected. pne of said mixers.

11. In a mixing plant, the combination of a plurality of mixers located at spaced points about the periphery of a central charging zone, an annular open top reservoir mounted for rotation about the vertical center line of said charging zone and having an outlet spout swingable into registry with any selected one 01' said mixers, a stationary water batcher tank located above said reservoir, and said tank having a plurality. of

outlets positioned to discharge into said open top reservoir irrespective of the rotational position of the latter, said tank outlets corresponding in number to the number of mixers and being positioned so that at least one of said tank outlets discharges directly into said reservoir outlet spout when the latter is in charging position for any one of said'mixers.

12. In a concrete mixing apparatus the combination of, a mixer having a charging opening,

a chute structure ior supplying aggregates to said mixer charging opening, a cement supply conduit leading downward into the chute structure for the gravitational flow of dry cement to a point lying between streams of aggregates in the chute structure, and means for spreading laterally the falling stream of cement to insure its diflusion into the streams of aggregates at the sides thereof.

13. In a concrete mixing apparatus, the combination of a mixer having a charging opening, means for directing a stream 01. aggregates into said mixer charging opening, means for supplying a stream of dry cement to interior of the stream of aggregates prior to its entry into the mixer, and means for spreading the stream of dry cement laterally substantially throughout the stream of aggregates as it enters the latter.

14. In a concrete mixing apparatus, the combination of a supply hopper having an outlet opening in its bottom, a mixer having a charging opening, means for directing a plurality of streams of aggregates into the hopper along separate paths lying along its inner face and converging at its center line, a dry .cement supply means for directing a stream of dry cement vertically downward substantially along the center line of said hopper, and means including a deflector cone the stream: of dry-cement for spreading the same laterally into the streams oi aggregates and means for directing themixed streams of material from said hopper outletto the mixer.

15. In a mixing plant an apparatus for charging water into a mixer comprising, in combination, means for segregating a batch of water of predetermined amount, and means operative automatically upon the initiation of its operation to direct the water from said batcher means into a mixer in an initial large stream comprising a major portion of the batch and thereafter continuing the charging of the water in a relatively smaller stream prolonged throughout a selected interval of time. 7 7

CHARLES S. J OHNBON.

located within said hopper and in alinement with

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