US2286067A - Trough washer - Google Patents

Description

June 9, 1942. N. DAVIS ETAL, 2 286,057

THOUGH WASHER Original Filed March,'7, 1938 5 Sheets-Sheet l fzeywezans I JVeZsan 1,. Fae/'51s James .33 firz'mhaafer 17202724 0. ar/ 437a June 9, 1942.

N. L. DAVIS ETAL TROUGH WASHER s Sheets-Sheet 5 Original Filed March 7, 1938 1% m5 0. Car/ZLSZe Jifazwzyof Patented June 9, 1942 TROUGH WASHER Nelson L. Davis, Chicago, 111., James D. S. Drinkwater, Stockport, England, and Thomas 0. Carlisle, Chicago, Ill., assignors to Link-Belt Company, Chicago, 111., a corporation of Illinois Original application March 7, 1938, Serial No.

194,358. Divided and this application February 10, 1940, Serial N0. 318,216

Claims.

This is a divisional application based on our co-pending application Serial Number 194,358, filed March '7, 1938.

Our invention is illustrated more or less diagramatically in the accompanying drawings, wherein- Figure l is a side elevation in part section of an apparatus adapted to carry out our process;

Figure 2 is a plan view;

Figure 3 is a section along the line 33 of Figure 2 Figure 4 is a longitudinal section on an enlarged scale along the line 4-4 of Figure 2;

Figure 5 is a detail view.

Like parts are designated by like characters throughout the specification and drawings.

I is a trough conveyor conveying the coal, or other material to be treated, to and discharging it into the hopper 2 whence it flows through the chute 3 across the apron 4 in the feed trough 5. G is a water pipe controlled by the valve I discharging water through the nozzle 8 into the trough 5 beneath the apron 4 so that as the stream of coal passes down over the apron it meets a stream of water coming from beneath i the apron and the coal and water travel together in the same general direction down the chute 5. The chute 5 is supported for angular adjustment at 9. I0 is a trough washer or stratifying trough, some of the details of which are shown in Figure 4. It comprises a trough II having a cover I2 and this trough may, if desired, have a longitudinal dividing wall or dam I3 along its floor, which wall may also be found, if desired, in the chute 5. stream of coal and water to generally parallel lines and discourage zigzag or cross flow in the trough.

In the floor of the trough II extending clear across the trough are two refuse discharge ports 54, I5. There might be one or there might be more than two, depending upon the capacity desired, the characteristic of the coal and the like. Each of these ports is associated with control and delivery elements which are identical and a description of one will suflice for both.

It is a barrage at the upstream edge of the port. It is adjustable in a direction perpendicular to the longitudinal axis of the stratifying trough and so generally in a horizontal direction.

Its sole purpose is to constrain the 1 I1 is a barrage at the downstream edge of each port, which barrag is adjustable parallel with the barrage I6 and also adjustable longitudinally along the line of flow of material in the trough.

The barrages I6 and I1 illustrated especially in Figures 4 and 5 are mounted for adjustment, the barrage I6 by the use of bolts I00, nuts IN, the bolt passing through a slot in the barrage I6 so that by loosening the nut, this barrage may be moved up and down in a direction normal to the floor of the trough II. The barrage I1 is mounted by means of a bolt I02, and nut I03 on a movable bracket I04 which bracket is slotted at I05 to permit up and down movement of the bolt I02. The bracket I04 is also slotted at I06 to engage the bolt I01 and nut I08 so that the bracket I04 may be moved in a direction generally parallel with the floor of the trough II. It is to be noted that both of the barrages themselves are normal to the floor of the trough and the upstream barrage may be moved only in a plane normal to the floor of the trough and parallel with it and both these barrages are short angled in structure. There are no ramps, inclined structures or anything of that kind, the result being that they exert a sharp and positive separating action on the coal as distinguished from the humps or ramps or elevations in the floor of the trough.

I8 is a floor extending downwardly and rearwardly inclined from the upstream edge of the port. It terminates in a cylndrical portion I9 and a rearwardly extended portion 20 communicating with the elevator hopper 2| 22 is a cover having a manhole and cover 25 extending upwardly from the elevator hopper 2I beyond the downstream edge of the port I4 to engage the under side of the trough II. 24 is a starwheel gate or valve concentric with the cylindrical member I9. It has associated with it a pivoted gravitally held flap 25 having a curved cylindrical portion 26, also generally concentric with the gate 24. 21 is an angularly adjustable floor plate overlying the floor I8. The purpose of the flap 25 with its extension 26 is merely to limit the size of the column of material which passes out through the port l8 and is controlled by the gate 24 and to provide for an overload release in the event that there is a tendency for the large particles of coal to jam in the star wheel. The purpose of the angular adjustment of the floor plate 21 is to control the rate of flow of refuse to the star wheel. The adjustment is ordinarily made for the conditions at a mine with reference to the size of the coal and the general character of it, and does not need to be changed unless conditions radically change. For instance, if the size of the coal particles being treated change radically, it might, under some circumstances, be necessary to change the inclination of the plate 21. Under ordinary circumstances, however, the control is by adjustment of the rate at which the star wheel is rotated, as will hereinafter appear.

Extending upwardly from one side of the elevator hopper 2| is an elevator boot 29 containing a bucket elevator, which bucket elevator extends above the trough I9 and discharges into a chute 3|, which in turn discharges into a trough 32. If there is more than one port |5 and more than one elevator, each elevator similarly discharges, as indicated in Figure 1, into the trough 32. 33 is a chute in continuation of the trough l9 through which the cleaned coal from the upper strata of the trough is discharged as a finished product.

The elevator hoppers 2| and boots 29 are water tight, and they are kept supplied with water from the stratifying trough I9. Under ordinary circumstances, no make-up water. is required, but if it should happen that the elevators carrying refuse and some water out of the trough I carried enough to cause a downward current of waterthrough the ports l4 and I5, then make-up water to prevent this will be added from a pipe 34 controlled by a valve 35 discharging into each hopper 29 adjacent its lower end, because it is important that the water below the wash or stratifying trough IE3 be static without any upward or downward current, which would otherwise interfere with the separating action.

As the refuse and coal travel down the trough 5 in the same general direction at high velocity, stratification will take place, the heavier particles seeking the bottom of the trough, the

lighter particles stratifying themselves above the heavier. In this particular instance, the coal at the top and the refuse at the bottom. If we were treating iron ore it would be the other way, and the refuse would be at the top and the iron ore at the bottom. In any event, the heavy material seeks the bottom and dams up behind the barrage It to some extent. The height of this barrage is determined empirically depending upon the conditions of operation, and tends to deflect the water stream and the coal and refuse particles in it upwardly away from the floor of the trough. The lighter particles will be more responsive to this deflecting action than the heavier, and so the downstream barrage I! will be adjusted, both vertically and horizontally to catch the under strata and defleet the refuse into the port 14, allowing the coal to pass over. If one port only is used, the barrage I! will be set so high that all the refuse particles will be intercepted and only coal. will pass over. On the other hand, if there are more than one port, as shown in Figure 4, there are two, the upstream barrage I! will be set in such position that some refuse and coal will pass over it. The refuse will further bank up behind the downstream barrage l6 and the second barrage i! will be set high enough so that only coal will pass over and refuse will pass through the port l 5, and the same thing will continue if more than two ports are used.

Once the refuse has been caught by the barrage I1, it must be removed, and it must be removed at a rate substantially as rapid as the rate at which the barrage catches it because otherwise if it is removed too fast too much coal will come out and if it is removed too slow, the refuse will pile up and be washed over the barrage Mounted for convenience on cross frames 36 associated with the cover I2 of the trough |9, is a reduction gear motor 3! which drives a variable speed control gear 38 which in turn through by manipulating the variable speed control gear 38, may control the rate of speed at which the star wheel operates and so control the rate at which refuse is discharged through the gate I4 because the star wheel 24 offers when at rest a positive obstruction to flow through the port I4. The elevators 39 in the boots 29 are driven by motors 44, belts and pulleys 46, and it is necessary that these elevators be driven only at such a speed as will be sufiicient to take the maximum amount fed to the hopper 2| by the star wheel 24.

The chute 32 conducts therefuse discharged from the elevators'39 to a jig washer 45. There will ordinarily be enough water elevated with the refuse by the conveyors 3D to insure the flow of the refuse along the chute 32 to the jig. If necessary, however, an additional water supply may be provided from pipe I45 controlled by valve 41. The refuse is discharged'from the chute 32 into the water bed of the jig and travels in the direction of the arrows in Figure 2 across the air cells 48, 49. These air cells are closed at their upper extremities by perforated or screen floors 59, 5|. An adjustable barrage 52 is interposed between the floors5fl and 5|. The floor 59 slopes downwardly in a direction opposed to the flow of refuse. The floor 5| is generally horizontal. The solid material is stratified on these floors with the refuse seeking the lower strata and the coal the upper. The general direction of travel is from the right to the left in Figure l and the coal and some of the refuse travels over the barrage 52, the final separation taking place on the floor 5|. The refuse caught by the barrage 52 on the floor 59 passes out through the port 53 controlled by a star wheel gate 54, discharges into the elevator boot 55 where the elevator 56 carries it, up above the water level, discharging it into a hopper 5'5 whence it runs off as finished refuse through a chute 53, no further treatment for this refuse being contemplated. The coal of the upper strata is discharged from the floor 5| through a coal chute 59 and may be mixed with the coal discharged through the chute 33 if desired. The refuse, sinking to the bottom along the floor 5|, together with a certain amount of coal, passes out through the port 60 controlled by a similar star wheel gate BI, is discharged into the elevator boot 62, raised by the elevator 63, is discharged into a hopper 64, travels over a screen 65, the fines being discharged as refuse without further treatment. The material which fails to pass through the screen passes through a crusher 66, travels along a chute 61, back to the chute 52, and is recirculated. Thus only that refuse larger than a predetermined minimum is recirculated and it is crushed before recirculation down to such a size that upon its next passage through the machine it will pass through the screen and escape.

The pulsation ofthe water column in the cells 48 and 49 is caused by automatic control valves 68 which are supplied with air froman air chamber 69. Manual control valves are interposed between the pulsating valve 68 and the air chamber. It will be understood that each of these valves 68'admits air into a chamber H on one side of the jig. Air is alternately admitted and released from those chambers. When it is admitted under pressure it forces the water up. When it is released the upward movement of the water ceases. The result of this is that there is a pulsating effect of the water applied directly to the sheet of coal traveling over the screened or perforated fioors at the under side of the coal bed. This pulsating effect of the water only forces separating and floating streams of water upwardly through the bed and insures stratification, and thus the coal'in its passage through the apparatus is first subjected to a separating effect in the trough washer wherein water and coal travel in generally the same direction, and then is subjected to a separating effect wherein the water and coal travel generally at right angles, the first treatment being a large capacity generally inaccurate treatment and the second treatment being a small capacity highly accurate separation.

In the specification and in the claims we have referred to coal and refuse merely for the sake of convenience and because it happens that this process and apparatus has been successfully used on coal. It will be understood of course, however, that the process and apparatus is equally applicable to the treatment of any kind of material which can be gravitally separated, and sometimes the lighter material is the value and the heavy material refuse, as in the case of coal, and at other times, for instance if we are dealing with iron ore or lead or zinc or any other metalliferous ores, the values are the heavy materials and the refuse are the lighter materials. Of course the relative sizes and capacities of the conveyors, ports, and gates to handle the refuse and the values will be changed in design to take care of proportional differences in volume and weight, and the illustration by means of a coal handling apparatus and the use of language especially pertinent to coal treating is merely for the sake of convenience and it is understood that that language is not intended to specifically limit the claims to a coal treating apparatus.

It will be understood, also, that the crushing and recirculating step may be omitted. Under some circumstances it is desirable, in other cases it is not necessary.

We claim:

1. A mineral washer comprising a downwardly inclined trough having a port in the bottom thereof, a fixed floor downwardly and rearwardly inclined from the upstream edge of the port, a cylindrical extension in continuation of the floor, a star wheel gate mounted for rotation concentric with the cylindrical extension, a subfloor associated with the fixed floor, and means for angularly adjusting it about a pivot axis immediately ad acent the upper edge of the fixed floor.

2. A mineral washer comprising a downwardly inclined trough having a port in the bottom thereof, a fixed floor downwardly and rearwardly inclined from the upstream edge of the port, a cylindrical extension in continuation of the floor, a star wheel gate mounted for rotation concentric with the cylindrical extension, a subfiocr associated with the fixed floor, and means for angularly adjusting it about a pivot axis immediately adjacent the upper edge of the fixed floor, an apron pivoted adjacent the downstream edge of the port having a cylindrical extension. concentric with the star wheel gate.

3. A mineral washer comprising a downwardly inclined trough having a port. in the bottom thereof, a fixed floor downwardly and rearwardly inclined from the upstream edge of the port, a cylindrical extension in continuation of the floor, a star wheel gate mounted for rotation concentric with the cylindrical extension, a subfloor associated with the fixed floor, and means for angularly adjusting it about a pivot axis immediately adjacent the upper edge of the fixed floor; an apron pivoted adjacent the downstream edge of the port having a cylindrical extension concentric with the star wheel gate, a hopper into which the star wheel gate discharges, a connection between the hopper and the cylindrical extension of the fixed floor, and. an. opposed connection between the hopper and the undersideof the trough, and closures for the spaces between said connections.

4. A mineral washer comprising a downwardly inclined trough having a port in the bottom thereof, a fixed floor downwardly and rearwardly inclined from the upstream edge of the port, a cylindrical extension in continuation of the floor, a star wheel gate mounted for rotation concentric with the cylindrical extension, a subfl'oor associated with the fixed floor, and means for angularly adjusting it about a pivot axis immediately adjacent the upper edge of the fixed floor, an apron pivoted adjacent the downstream edge of the port having a cylindrical extension concentric with the star wheel gate, a hopper into which the star wheel gate discharges, a connection between the hopper and the cylindrical extension of the fixed floor and an opposed connection between the hopper and the underside of the. trough, and closures for the spaces between said connections, an elevator boot extending upwardly from the hopper, the entire assembly beneath the port being water tight.

5. A mineral washer comprising a downwardly inclined trough having a port in the bottom thereof, a fixed floor downwardly and rearwardly inclined from the upstream edge of the port, a cylindrical extension in continuation of the floor, a star wheel gate mounted for rotation concentric with the cylindrical extension, a subfloor associated with the fixed floor, and means for angularly adjusting it about a pivot axis immediately adjacent the downstream edge of the port having a cylindrical extension concentric with the star wheel gate, a hopper into which the star wheel gate discharges, a connection between the hopper and the cylindrical extension of the fixed floor and an opposed connection between the hopper and the underside of the trough, and closures for the spaces between said connections, an elevator boot extending upwardly from the hopper, the entire assembly beneath the port being water tight, and means for controllably adding water to such assembly to maintain the water in the system quiescent.

6. A mineral washer comprising a downwardly inclined ported trough, a fixed chute dowm wardly and forwardly inclined from the upstream edge of the port. a pivoted apron downwardly and forwardly inclined from the downstream edge of the port, the chute and the apron each terminating in opposed cylindrical exten sions, a star wheel gate mounted for rotation concentric with and in close relationship to said extensions, a hopper beneath the star wheel and a liquid tight connection between the hopper, the cylindrical extension on the chute and the "trough whereby the whole assembly forms a water tight receptacle, a false floor associated with the chute, pivoted at its upper end adjacent the upper end of the chute and terminating adjacent the star wheel, means for adjusting the angle of inclination of the false floor with respect to the chute, an elevator boot extending upwardly from the hopper, and an elevator therein, means adapted to supply water to the hopper to compensate for that withdrawn by the elevator and to maintain a constant amount of water in the system whereby liquid current through the port is effectually prevented.

'7. A mineral washer comprising a downwardly inclined ported trough, a fixed chute downwardly and forwardly inclined from the upstream edge of the port, a pivoted apron downwardly and forwardly inclined from the downstream edge of the port, the chute and the apron each terminating in opposed cylindrical extensions, a star wheel gate mounted for rotation concentrio with and in close relationship to said extensions, a hopper beneath the star Wheel and a liquid tight connection between the hopper, the cylindrical extension on the chute and the trough whereby the whole assembly forms a water tight receptacle, a false floor associated with the chute, pivoted at its upper end adjacent the upper end of the chute and terminating adjacent the star wheel, means for adjusting the angle of inclination of the false floor with respect to the chute.

8.'A trough washer for cleaning coal and the like comprising a stratification trough, a discharge trough leading from the lower end thereof, a feed trough leading to the upper end thereof, the angle of inclination of the feed trough b ing adjustable, a port in the floor of the stratification trough, barrages normal to the floor'of the stratification trough on the upstream and downstream sides of the port, one of them being adjustable generally vertically, the other both vertically and horizontally the barrages and the inclination of the feed trough being subject to manual control and normally fixed in position during operation of the washer, a bolt and slot adjusting means associated with the barrages and the stratification trough whereby the barrages may be adjusted and fixed in adjusted position, a chute having an inclined floor extending downwardly and forwardly from the upstream edge of the port, and means for adjusting its angle of inclination, and a gate" at the lower edge of the chute floor, means for operating it to control the rate of discharge of material along the floor.

9. A trough washer for cleaning coal and the like comprising a stratification trough, a discharge trough leading from the lower end thereof, a feed trough leading to the upper end thereof, the angle of inclination of the feed trough being adjustable, a port in the floor ofthe stratification trough, barrages normal to the floor of the stratification trough on the upstream and downstream sides of the port, one of them being adjustable generally vertically, the other both vertically and horizontally the barrages and the inclination of the feed trough being subject to manual control and normally fixedin position during operation of the washer, a bolt and slot adjusting means associated with the barrages and the stratification trough whereby the barrages may be adjusted and fixed in adjusted position, a chute having an inclined floor and means for adjusting-its angleof inclinationextending downwardly and forwardly from the upstream edge of the port, and a gate at the lower edge of the chute floor, means for operating it to control the rate of discharge of material along the floor, a hopper beneath and adapted to receive material discharged from the gate, an elevator boot extending upwardly from the hopper and an elevator in the boot, and means for supplying make-up water to the hopper to compensate for withdrawal of water and solids by the elevator and prevent flow of liquid through the port.

10. In combination, a downwardly inclined separating trough, a port extending across the floor of the trough, a fixed floor plate inclined downwardly from the upstream edge of the port, apivoted floor overlyng the fixed floor pivoted adjacent the upstream edge of the port, both floors being downwardly inclined in the direction of the flow of material, means for adjusting the angular position of the pivoted floor, a segmental cylindrical extension at the lower end of the fixed floor, a cover plate pivoted adjacent the downstream edge of the port and having a segmental cylindrical extension in opposition to the one associated with the fixed floor plate, a star wheel interposed between the two segmental cylindrical extensions and closing the hopper formed by the fixed floor plate and the cover plate, the pivoted floor plate terminating adjacent the periphery of the area passed over by the rotating star wheel.

11. A trough washer for cleaning coal and the like comprising a feed trough, a stratification trough adapted to receive material therefrom, a discharge trough leading'from the lower end of the stratification trough, all the troughs being downwardly inclined and in alignment to define a continuous passage for liquid, means manually operative during the operation of the device for adjustably changing the angle of inclination of the feed trough, a plurality of spaced ports in the floor of the stratification trough, a chute closing each of said ports, downwardly inclined from the port in the general direction of the flow of liquid through the trough, an inclined floor in each chute, means, manually operative during the operation of the device, for changing the angle of inclination of the floor and mechanically actuated means at the end of the chute adapted positively to control therate of discharge of solid material from the chute, barrages extending upwardly from the'floor of the stratification trough, one adjacent the front and one adjacent the rear boundaries of each port, the upstream barrage being adjustable in a direction generally perpendicular to the floor of the trough, the downstream barrages being adjustable both parallel with and generally perpendicular to the floor of the trough, each adjustment of each barrage being independent of any of the other adjustments.

12. A trough washer for cleaning coal and the like comprising a feed trough, a stratification trough adapted to receive material therefrom, a discharge trough leading from the lower end of the stratification trough, all the troughs being downwardly inclined and in alignment to define a continuous passage for liquid, means manually operative during the operation of the device for adjustably changing the angle of inclination of the feed trough, a plurality of spaced ports in the floor of the stratification trough, a chute closing each of said ports, downwardly inclined from the port in the general direction of the flow of liquid through the trough,

an inclined floor in each chute, means, manually operative during the operation of the device, for changing the angle of inclination of the floor and mechanically actuated means at the end of the chute adapted positively to control the rate of discharge of solid material from the chute, barrages extending upwardly from the floor of the stratification trough, one adjacent the front and one adjacent the rear boundaries of each port, the upstream barrages being adjustable in a direction generally perpendicular to the floor of the trough, the downstream barrages being adjustable both parallel with and generally perpendicular to the floor of the trough, each adjustment of each barrage being independent of any of the other adjustments, the means for controlling the discharge of material including a star wheel gate at the lower edge of the chute floor, means for rotating the star wheel at controlled speed to control the rate of discharge of material along the inclined floor.

13. A trough washer for cleaning coal and the like comprising a feed trough, a stratification trough-adapted to receive material therefrom, a discharge trough leading from the lower end of the Stratification trough, all the troughs be ing downwardly inclined and in alignment to define a continuous passage for liquid, means manually operative during the operation of the device for adjustably changing the angle of inclination of the feed trough, a plurality of spaced ports in the fioor of the stratification trough, a

chute closing each of said ports, downwardly inclined from the port in the general direction of the flow of liquid through the trough, an inclined floor in each chute, means, manually operative during the operation of the device, for changing the angle of inclination of the floor and mechanically actuated means at the end of the chute adapted positively to control the rate of discharge of solid material from the chute, barrages extending upwardly from the floor of the stratification trough, one adjacent the front and one adjacent the rear boundaries of each port, the upstream barrages being adjustable in a direction generally perpendicular to the floor of the trough, the downstream barrages being adjustable both parallel with and generally perpendicular to the floor of the trough, each adjustment of each barrage being independent of any of the other adjustments, the means for controlling the discharge of material including a star wheel gate at the lower edge of the chute floor, means for rotating the star wheel at controlled speed to control the rate of discharge of material along the inclined floor, an apron pivoted above the star wheel extending downwardly and rearwardly toward the wheel and having a cylindrical extension adapted to partially encircle the wheel, the apron being free to rise against the influence of gravity to permit passage of oversize particles through the gate.

14. A trough washer for cleaning coal and the like comprising a feed trough, a Stratification trough adapted to receive material therefrom, a discharge trough leading from the lower end of the Stratification trough, all the troughs being downwardly inclined and in alignment to define a continuous passage for liquid, means manually operative during the operation of the device for adjustably changing the angle of inclination of the feed trough, a plurality of spaced ports in the floor of the Stratification trough, a chute closing each of said ports, downwardly inclined from the port in the general direction of the fiow of liquid through the trough, an inclined floor in each chute, means, manually operative during the operation of the device, for changing the angle of inclination of the floor and mechanically actuated means at the end of the chute adapted positively to control the rate of discharge of solid material from the chute, barrages extending upwardly from the floor of the Stratification trough, one adjacent the front and one adjacent the rear boundaries of each port, the upstream barrages being adjustable in a direction generally perpendicular to the floor of the trough, the downstream barrages being adjustable both parallel with and generally perpendicular to the floor of the trough, each adjustment of each barrage being independent of any of the other adjustments, an apron pivoted above the star'wheel extending downwardly and rearwardly toward the wheel and having a cylindrical extension adapted to partially encircle the wheel, the apron being free to rise against the influence of gravity to permit passage of oversize particles through the gate.

15. A trough washer for cleaning coal and the like comprising a feed trough, a stratification trough adapted to receive material therefrom, a discharge trough leading from the lower end of the Stratification trough, all the troughs being downwardly inclined and in alignment to define a continuous passage for liquid, means manually operative during the operation of the device for adjustably changing the angle of inclination of the feed trough, a plurality of spaced ports in the floor of the stratification trough, a chute closing each of said ports, downwardly inclined from the port in the general direction of the flow of liquid through the trough, an inclined fioor in each chute, means, manually operative during the operation of the device, for changing the angle of inclination of the fioor and mechanically actuated means at the end of the chute adapted positively to control the rate of discharge of solid material from the chute, barrages extending upwardly from the floor of the stratification trough, one adjacent the front and one adjacent the rear boundaries of each port, the upstream barrages being adjustable in a direction generally perpendicular to the floor of the trough, the downstream barrages being adjustable both parallel with and generally perpendicular to the floor of the trough, each adjustment of each barrage being independent of any of the other adjustments, and a star wheel gate at the lower edge of the chute floor, means for rotating the star wheel at controlled speed to control the rate of discharge of material along the inclined floor, a hopper beneath and adapted to receive material discharged from the star wheel gate, a closure interposed between the hopper and the underside of the trough adapted to protect the apron, there being access to the apron through the closure, the assembly including the hopper, the chute, the elevator boot, and all other parts below the port in the floor of the wash trough being water tight, whereby the water within the area below the trough is maintained quiescent.

NELSON L. DAVIS. JAMES D. S. DRINKWATER. THOMAS O. CARLISLE.

Images