US2646172A - Centrifugal separator - Google Patents

Description

July 21, 1953 5, cox ET AL 2,646,172

CENTRIFUGAL SEPARATOR Filed Sept. 19, 1947- 4 Sheets-Sheet 1 JNVENTORS. fir'aJ/eg/ 6. Cox.

7207714.? Jl/a 77s.

July 21, 1953 Filed Sept. 19, 1947 B. G. COX ET AL CENTRIFUGAL SEPARATOR 4 Sheets-Sheet 2 y 1953 B. G. cox El AL CENTRIFUGAL SEPARATOR 4 Sheets-Sheet 3 Filed Sept. 19, 1947 .I 75 a lll IN V EN TORS ZraJ/ey a Cox. 772077245 [ll 477.5. BY

5 v irro/avzy July 21, 1953 B. G. COX El AL CENTRIFUGAL SEPARATOR Filed Sept. 19, 1947 4 Sheets-Sheet 4 INVENTORS.

G Z/ Cox, Y flames f arzat W OF/VZK Patented July 21, 1953 2,646,172 CENTRIFUGAL SEPARATOR Bradley G. Cox, Saginaw, and Thomas Evans, Tuscola, Mich., assignors to Baker Perkins Inc., Saginaw, Mich., a corporation of New York Application September 19, 1947, Serial No. 774,97

27 Claims.

This invention relates broadly to new and useful improvements in centrifugal separators of the type used primarily for separating the mother liquor or sirup from sugar crystals.

In the manufacture of sugar, mother liquor is centrifugedfrom the crystals, andthe latter are then washed with water to removeany liquor adhering thereto. Usually the crystals are permitted to accumulate to a considerable depth in V the centrifuge basket and are removed from time .to time by suitable mechanical strippers.

A curb ring is provided at the rim of the basket .to prevent the crystals from spilling during the centrifuging operation. This curbring must meet certain'rigid specifications and no entirely satisfactory way of mounting it on the basket has heretofore been devised. For example, the curb ring must rotate with the basket to prevent undesirable heat from being developed due to friction between the parts. Further, the curb rin must seal the rim of the basket during the centrifuging operation but be readily removable so that the crystals can be easily stripped from the basket. The curb ring cannot be fastened directly to the centrifuge basket, since it then interferes with the operation of the mechanical strippers.

The usual practice is to mount the rings on the stripper so that it moves with the latter. However, the stripper is disposed'in the basket and the posts which support the curb ring prevent the crystals from building up uniformly on the basket. As a result, the sugar crystalsdo not' deposit uniformly on the wall of the basket, the weight of the basket is not balanced and a gymtory effect results during the centrifuging operation. Further, the supporting posts intercept the streams of sirup and wash Water charged to the basket and cause much splashing and unnecessary spillage.

An important object of the present invention is to provide a centrifugal separator of the abovementioned character wherein the curb ring is supported in a novel manner by means outside up of sugar crystals in the basket.

Still another object of the invention is to provide a centrifugal separator of the above-men'- tioned character wherein the curb ring and its adjuncts in no way interfere with stripping of v the sugarcrystals from the basket."

2 Yet another object of the invention is to provide a centrifugal separator of the above-mentioned character wherein the curb ring is uniquely shaped and associated with the basket to prevent the syrup in the basket from leaking over the top of the basket and mixing with the sugar crystals which'have been removed from the basket.

A still further object of the invention is to pro.- vide a centrifugal separator of the above-mentioned character having novel means for maintaining the mother liquor and wash water separate from each other.

A yet further object of the invention is to provide a centrifugal separator of the above-mentioned character which is more efficient in operation and is capable of handling a greater volume of sirup than has heretofore been possible. Other objectsand advantages of the invention will be apparent during the course of the following description.

In the drawings forminga part of this specification and wherein like numerals are employed to designate like parts throughout the same:

' Figure 1 is a vertical sectional View through a centrifugal separator embodying the invention and showing the centrifugal basket in its normal,

raised position;

Fig. 2 is a view similar to Fig. 1 but showing the centrifugal basket lowered to discharge the sugar crystals; l

Fig. 3 is an enlarged, fragmentary View of the portion of Fig. 2 enclosed in the circle 3;

Fig. 4 is an enlarged, fragmentary, transverse sectional view taken on the line 44 of Fig. 1, and particularly illustrating the construction of the centrifugal basket;

Fig. 5 is an enlarged, fragmentary view of the portion of Fig. 1 enclosed in the circle 5;

Fig. 6 is an enlarged, fragmentary view of the portion of Fig. 1 enclosed'in the circle 6 but showing the curb ring raised slightly from centrifugal basket; Fig. 7 is a vertical sectional view taken on the line of Fig. 1, particularly illustrating the spraying device for washing out the centrifugal basket underneath the stripper;

Fig. 8 is an enlarged, fragmentary view of the i portion of Fig. 1 enclosed in the circle 8;

Fig. 9 is an enlarged fragmentary, vertical sectional view showing a modified means for raising and lowering the curb ring; and f Fig. 10 is a diagrammatic'view showing the electrical network, hydraulic fluid lines, and water the piping which control, operate, and supply the centrifugal separator.

Considered in certain of its broader aspects, the present invention comprises a centrifuge basket mounted in a suitable open framework 22 and rotatably driven by a motor 24 through a vertical tubular shaft 26. Also mounted on the shaft 26 for. rotation therewith and fitting snugly within the basket 28 is a disk-shaped stripper 28. The stripper 28 is fixed on the shaft 26 against axial movement as well as against rotation, and

the basket 20 is moved up and down on the shaft relative to the stripper by a fluid motorgfifl. ;Nor

mally the basket 20 is raised as shown in Fig. 1, so that the stripper 28 is disposed at the bottom thereof; however, when sugar crystals-accumulate to a desired depth in the basket, it is lowered to the position shown in Fig. 2. .the basket 26 moves downwardly, the crystals aresupported by the stripper plate 28 and spill overthe' top of the basket into an outer annular surrounding chamber-3|. 'From th chamber 3l,-the crystals are expelledby means "hereinafter described in detail into a dischargespout 32.

--A-slurry of sirup and sugar crystalsis charged to-the-basketifi througha pipe'34 controlled by a-charging valve, not shown, and the contents are preventedfrom' spilling over the top of the basket by a curb ring 36. Th valve conveniently may be a valve-of the-type shownin our copending application Serial No. -772,367'which was filed September5, 1 947. The charging operation may be accomplished-while'the basket 20 is rotating at relatively high speed and the liquor or sirup is thrown outwardly bycentrifugal-force through the foraminous vertical wall of the basket into an inner annular surrounding chamber 38. The curb ring -36 is supported by-the stripper 28 through rods 40 and 42 and a connecting ring 44. The stripper '28 drives the curb ring 36 at the-same rotative speed as the basket:28 and holds it axially fixed at all times. When thebasket 2t 'is-fully raised, the open "top thereof is pressed solidly against the under surface of-curb ring 36 which seals the basket at-the rim and prevents the contents of the basket from spilling. However, when the-basket-21l is lowered, it drops away fromthecurb ring 36, so that'the sugar crystals can be stripped or discharged over the top of the basket inthe manner hereinabove described. After-the sugar 'crystals'have accumulatedto the desired depth in basket 20, fiowthrough the supply pipe 34 is'shut off by means hereinafter describedin detail and the crystals in the basket are subjected to a water rinse. Wateris introduced into the basket'through a pipe 46-which extends downwardly between the drive shaft "26 and. the curb ring 36. The rinsewater is thrown outwardly from the basket 20 into the chamber 38 by centrifugaLfOrce-in the same manner as the mother liquor. This water washesaway any sirup still adheringto the crystalsin the basketlfl and also. cleans the basket .and the walls of the surrounding chamber 38.

. Both the mother liquor and the rinse waterare discharged from the chamber 38 through a port 48. However, the mother liquor is subjected to further processing, and it is therefore desirable that it be collected separately from the rinse water. In order to accomplish this result, concentric annular housings 50 and 5| are mounted around the lower portion of chamber 38 which housings have chambers 52 and 54 provided with inner annular inlets 56 and 58. Theouter housing 50 is fixed and the inlet is positioned to .5! is lowered, as shown in Fig. 1, during the charging operation, so that the mother liquor is -.c0llectedin the outer chamber 52 and raised .during the rinsing operation to the position shown in-Fig. 8, so that the rinse water is collected inthe inner .chamber 54. discharged from chamber 52 through an outlet The mother liquor is 1.60:1forgfurthermaprocessing and the rinse water is discharged from chamber 54 through an outlet 62 to any suitable place of disposal.

From time to time during operation of the separator it is necessary to wash betweenthe bottom of -the'-bask-et-2-9 andthe stripper -28-to remove sirupand occasional sugar crystals which by-pass' the stripper. To this end, a wash-pipe 84 isarranged vertically below the basket ZB-With the discharge end thereof facing upwardly toward the-bottom of the basket. The stream of water-frompipe fidis collected in a downwardly opening, annular groove 56 provided-in the bottom of thebasket 20 and passes upwardly into the basket through a series ofpassages 68. In this connection,-it will be observed that the annular groove -56 isformed with an upwardly and outwardly inclined outer wall T0 and that the passages -68 extend upwardly from this wall. As a result of this arrangement, substantially all the water-discharged by pipe 64 passes into the basket 28, and-very little water is lost as overflow or spillage.

The-pipe64 is carried by a fluid motor 12 which moves it vertically relative to the basket 26. This is necessary, sincethe outlet of pipe 64 should be disposed in close proximity to'the bottom of the basket '20 during the washing operation; however, during normal operation of the separator, the pipe 64-mustbe positioned a considerable distance below the basket in order not to interfere with vertical-movement of the latter.

Certain details of construction not readily apparent from the above general description are now given.

.Theba-sket 26 has a generally disk-shaped bottom "14 and a foraminous circular side wall 76. The latter is provided with a lining which filters the sugar crystals and permits the basket to slide easily on the stripper 28.

As perhaps best shown in Fig. 4, the lining comprises aplurality of similar vertically spaced wire rings 18 which fit snugly within the vertical wall 16 and fitted over each ring is a band 88 of sheet metal or the like. As shown in Fig. 5, each band 86 is essentially V-shaped in transverse section'and is arranged with the flange portions thereof in embracing relation to its respective ring I8. Also, it will be observed that the bands ,89 project substantially beyond the wires '58, and the projecting portions thereof are notchedto receive the vertical bars 82. Bars 82 are uniformly spaced-and the spacing issuch that the sugarciystals are retained but the liquor andrinse waterpass readily therebetween. Also, theinner vertical surfaces 84 of the bars 82 are flatand smooth .toslidably engage the stripper 28. In this connection, it will be observed that carrier bands 80 so that the'peripheryfof the stripper 28 engages only the vertical surfaces 84 and is not required to passover anyintersecting transverse members during vertical travel of the basket 20. Also, the, smooth surface presented bythe vertical strips 82; facilitates removal of the sugar crystals from the basket. I I

Thevertical drive shaft 26 extends axially through the basket. 20, and the bottom I4. of the basket is formed with. a centrally located upstanding boss 86 through which the shaft passes. A stuifingbox 88 on the boss 86 and surrounding the shaft 25 provides a fluid tight seal between the basket and the drive shaft. Drive shaft zepreferably is coupled to the motor 24 by a universal joint 96 and is'journaled for rotation in upper and lower bearings 92 and 94.

The upper bearing 92 "conveniently canbe attached to an overhead portion of the framework 22. An unbalanced load in the basket 20 oc-' casionally causes a gyratory effect; and, according to the present invention, this phenomenon is compensated by mounting the lower bearing 94 for-free floating movement in a guide 96 which in turn is fastened to bottom members of the frame 22. As a result ofthis construction, the lower bearing 94 is permitted to gyrate'freely within limits defined by the guide 96.

As suggested, the basket 20 is fixed to the shaft 26 and is movable vertically on the shaft .by the fluid motor 30. Specifically, the oylinder'eb of the motor 35} is arranged concentrically around the drive shaft 26 below the basket 2'3,

and the upper end thereof abuts against and is welded or otherwise fixed to the bottom it. Thus, the bOttOII'L'TQ- closes and the stuffing box 88 seals the upper end of the cylinder 98. A piston I90 is keyed, as at I02, to the cylinder 98 and as at I94 to the drive shaft'ZG. The key I04 connects the piston Illil to the drive shaft 23 for mutualrotation, and the key I82 connects the piston to the cylinder 98 for mutualrotation; however, the key IE4 axially fixes the piston on the drive shaft, whereas the key I02 is freely slidable in a guideway Iil'u which extends the full length of the cylinder 93. Thus, the drive shaft 26 rotatably drives the basket 26 through thev piston I30 and cylinder 98 and hydraulic pressure admitted to one side or the other of the piston will raise or lower the cylinder 98 and basket 25 as aunit on shaft 26.

According to the present invention, hydraulic fluid is supplied to the motor 33 throughthe shaft 26 to raise and lower the centrifugal basket 20. More s ecifically, a pipe I88 is mounted concentrically in the tubular shaft 26, which pipe extends from the upper bearing 92 to a point below the piston I09 and is sealed at its ends to the shaft 2E5. Hydraulic fluid is admitted into the shaft 26 above the pipe Itii through an inlet H2, and this fluid is conducted downwardly through the pipe I38 to discharge ports I I4 which open into the cylinder 98 below the piston Illil. Also, hydraulic fluid may be introduced into the v annular space IIIi between the shaft 26 and pipe inlet, I12, fluid pressure in the cylinder 98 below piston I00 will move the cylinder and basket 20 downwardly on the shaft 26. On the other hand, if valve I22 is operated to direct hydraulic fluid to inlet II8, fluid pressure in the cylinder 98 above piston I00 will move the cylinder'and basket 20 upwardly on shaft 26. Thus, by proper operation of the control valve I 22, the basket may be raised or lowered periodically without interrupting or checking the rotative speed of the basket. I

The stripper plate. 28 also is formed with a central boss I24 through which the shaft 26 passes and which is fixed to theshaft against rotation by a key I26. An annular shoulder I28 formed on shaft 26 below the stripper 28 and a collar I38 fixed on the shaft above the stripper by member I3I co-op-erates to hold' 'the latter axially fixed on the shaft. Thus, stripper plate 28 rotates in unison with the basket 26. How'- ever, when the basket 28 is lowered, crystals sup ported by the stripper 28 spill over the topof the basket into chamber 3 I.

The particular shape of the curb ring 36 and the manner in which it is associated with the basket 26 comprise an important feature of the invention. As perhaps best shown in Fig. 5, the inner annular portion I32 which projects radially inwardly across the basket 20 is downwardly offset to define a radially outwardly facing annular surface I34 which snugly fits an inturned flange I36 on the rim of the basket 20. Further, it will be observed that the surface I34 extends downwardly below the flange I33 to define an annular pocket I38, and'this pocket communicates with an annularseries of holes I40 which are provided in the side wall of the basket immediately below the flange I36. By reason of this unique construction, the mother liquor or sirup is prevented from leaking between the curb ring 36 and the rim of the basket 20. Any

sirup which tends to crawl up the side wall of the basket ischecked by the inturned flange and tends to accumulate in the pocket I38. Instead of working through the relatively tight joint between the basket 20, and the curb ring 36, the sirup follows the path of least resistance and fiows outwardly through the holes I 40. In this connection, it will be observed that the holes- I40 dischargethe sirup into thesurroundinginner chamber 33 and the sirup is then disposed of in the manner hereinabove described." Also, it

ring 36 is supported outside the basket '20 is another important feature of the invention. By reason of this construction, the supports are unobstruotively positioned, and atthe same time the curb ring is properly supported to rotate in unison 'with the basket 20 and stripper 28. Also, the curb ring effectively seals the top'ofthe basket and prevents leakage of sirup therefrom during the centrifuging operation. However, by

' reason of the unique manner in which the basket 20 and curb ring 36 are combined and correlated, the basket drops away from the curb ring during the discharging operation so that the crystals are readily expelled over the. top of the basket;

The chamber. 381which;is disposed immediately 'aroundzthe basket 29 is formed :by concentric walls .Id2 and I6.

The inner wall 1A9 depends from the basket 29 and the upper'edge thereof is formed with a horizontal flange. :46 which overlies and is spot welded or otherwise:fastened .to .anoutwardly extending flange I49 on' the basket.

Atits loweredge, the wall I44 is formed with an outwardly extending flange I59whichsupports an inwardly extending flange I52 .on the outer wall I42. The wall. i 52 extends tothe top of the'basket 29 and has an inwardly extending .flange I54 which fits snugly around the rim of -48 serves this sump.

The housings 59 and I are concentric to'each other and are U-shape'd in transverse section, as shown in Figs. 1 and 2. The outer'vertical walls of housings 59- and 5! extend above the inner walls thereof, and both outer walls are provided with angularly, inwardly andupwardly extending covers I56 and I53. In this connection 'it will be observed that the cover I56 pro-iects radially outwardly beyond the inner housing .5! and that the projecting eave' portion thereof pro jects over the inner wall of the outer housing 59 to seal the same. Also, it will be readily apparent from the drawings that the. inlets 56 and 58 of chambers 52 and 54 are formed by merely extending the outer wall of each housing 53 and 5I above the inner wall thereof.

The wash-water housing 5I is raised to bring inlet 58 into register with outlet port =58 by a series of levers I64 which are iulcrumed to the frame .22 and preferably are operated by a hydraulic cylinder I60 (Fig.

The crystal chamber 3! is formed byan annular sheet-metal housing I66 having an outer vertical wall- I 68 provided at the upper edge thereof with an inwardly extending annular flange I19 which terminates adjacent to and just below the periphery of curb ring 36. Housing I66 is stationary and is secured in any suitable manner to the frame 22. The bottom of housing I66 is separate from the vertical side wall I66 and comprises an annular plate I'I2 having a short, up-

standing, circular wall I14 at the inner edge thereof and adjacent the outer wall I42 of liquor chamber 38. Plate I12 is supported for rotation by sets of vertical and horizontal rollers I16 and I18 (Fig. 3). Each set of rollers is carried by a supporting bracket I89 which is fastened to and depends from the outer vertical wall I69 of housing I66. Below and fixed to the plate I72 is a pulley I82 which is rotatably driven by'a motor I84 through endless belts I86. Motor I84 rotates the plate I'I2 relatively slowly. Sugar crystals discharged into chamber 3| from basket 29 fall onto the rotating bottom plate I12 and are pushed ofi the plate into discharge spout 32 by a plow or baiile I88 which is carried by and projects radially, angularly inwardly from the wall I68 across the plate I2 (Fig. 2).

Any sirup or wash water which may drip onto the curb ring 36 or any crystals or sirup from the basket 29 which may overflow the curb ring are thrown by centrifugal force into a housing I99 which surrounds the upper part of the crystal housing H66. The housing I99 comprises a vertical circular wall I92 arranged concentrically to and spaced circumferentially from the wall I68 so that the latter wall, in effect, partitions the overflow chamber from the crystal chamber 3|. At the lower edge thereof, the wall I92 is formed with an inturned flange I94 which is secured to the wall I68, and at the upper edge thereof the wall I92 supports a cover I96 having a central opening I98 through which the drive shaft 26, sirupsupply pipe 34, and wash pipe 46 extend. Atthe bottom of housing I99 is a discharge pipe 299 which conducts any material thrown into the-housing back into the'process.

For a, detailed description of the wash pipe 64 and fluid motor I2, attention is directed to Fig. '7. It will be observed that fluid motor I2'comprises a cylinder 292 and a piston 294 mounted for reciprocation in the cylinder. The lower end of cylinder 292 is closed by a plate 296 and the upper end thereof is closed by a plug 299. Wash pipe 64 extends through and is slidably suported by the plug 298, and the end thereof within the cylinder 292 is fixed to the piston 294. Astuffing box 2I9 carried by the plug 298 provides a fluid tight seal with the pipe 64. The piston 294 has a central aperture 2I2 which opens through the side'thereof and communicates with-the spray pipe 64. A gauge tube 2I4 is welded or otherwise fixed on the upper face of the piston 294 and abuts against the closure plug 296 to limit upward movement of the piston 294 in the cylinder 292.

Hydraulic fluid is delivered to the cylinder 292 below piston 264 through a pipe 2I6 connected to the plate Also, hydraulic fluid may be supplied to the cylinder 292 above the-piston 294 through a pipe 2I8 which opens through the side of the cylinder immediately below the upper closure plug 268. When the piston 294 is at the upper limit of its travel, aperture 2I2 communicates with a pipe 229 which is screwed into the side wall of cylinder 292; and-the pipe 229 is connected to a second pipe 222 through a check valve 224 which permits liquid to flow from pipe 222 to pipe 229 but prevents reverse flow therethrough. Pipe 222 also is screwed into the side wall of cylinder 292 and is located immediately below the piston 299 when the latter is fully raised as shown in the drawing.

As suggested, the wash pipe 64 normally is lowered so as not to obstruct vertical travel of the basket 29. Therefore, in use, the first operation is to admit hydraulic fluid into the cylinder 292 through pipe M6 to raise the piston 294 to the position shown in Fig. 7 and to position the discharge end of wash pipe 64 in proximity to the basket 29. Hydraulic fluid admitted into cylinder 292 below piston 294 causes the latter to rise until it is stopped by the gauge tube 2I4. When the piston 2%, reaches the upper limit of its travel, it establishes communication between the cylinder 262 below the piston 294 and pipe 222. Hydraulic fluid then flows through pipe 222,

valve 22% and pipe 229 to the central aperture H2 and thence passes upwardly through wash pipe 64 which discharges it against the bottom of the housing in the manner hereinabove described. After the washing operation is completed, flow through pipe 2I6 is stopped and hydraulic fluid is admitted into the cylinder 292 above piston 296 through pipe 2I8. When piston 294 moves downwardly sufliciently to establish communication between the cylinder above the piston and pipe 229, check valve 224 automatically closes to prevent fluid from entering the central aperture 2I2 and locking thepiston.

59 An alternative structure for supporting the curb ring 36 is shown in'Fig. 9. I In the modified form of the invention, the supporting rods 42 are operated in unison by fluid motors 226 to raise and'lower the curb ring'36. As shownin the drawings, the rods 42 extend axially into the motor cylinders 228 through stufiing boxes 236 and-are fastened to pistons 232 which operate in the cylinders. Cylinders 228 conveniently may be, fastened to the bottomof the liquor housing Hydraulic liquid is supplied to the cylinders 223 alternately through pipes 234 and 236;and the operation is timed so that the pistons 232 are raised sufliciently to lift the curbring 36 from the basket 28 as shown in Fig. 6 just before the basket is lowered. In operation, the curb ring '36 may be returned to its closed position either before or after the basket 26 is raised to its charging position.

Reference is now had to Fig. 10 which shows the hydraulic and fresh water circuits for the separator as well as the electrical networkfor operating the various parts of the separator automatically and inproper sequence.- I

A pump 240 driven by motor242 draws hydraulic liquid from a tank244 through an inlet pipe .246 and discharges the same through an outlet pipe 248, Which outlet pipe supplies liquid under pressure to various fluid motors which operate .the movable parts of the separator.

In this connection, it will be observed that the charging valve 35 is operated by a fluid motor .250 and that the latter iscontrolled by a solenoid operated reversing valve 252. In the drawing, valve 252 is shown positioned to retract the piston in fluid motor 258 whereby to close the charging valve35. However, it will be readily apparent that if valve 252 is moved to the right,

as viewed in the drawing, hydraulic liquid;from

line 248 will advance the piston in fiuidmotor 258 and openthe charging valve 35. Hydraulic liquid forced from fluid motor 250 during operation of the same passes through reversing valve 252 and is conducted to a pipe 254 through either of pipes 256 or 258 depending on the position of theva-lve. Pipe 254 returns the-liquid to tank .244. a

draulic liquid under pressure passes from the supply pipe 248 through pipe 268to a solenoid operated reversing valve 262 and thence flows through one of pipes 264 or 266 to the fiuidmotor .168.

other of pipes 264 and 266 and this liquid flows to the return line 254 through apipe 212.

- In connection with the operation of basket 26, hydraulic liquid is conducted from the supply pipe 248 to the valve I22 through pipe'2'I4. Communication is established between the valve 422 and the motor 38 which operates the basket in the manner hereinabove described, and liquid To operate the wash water housing 5|, hy-

Manifestly, actuation of motor I60 causes fiuid to be returned to valve 262 through the ducts hydraulic fluid from the pressure side of I the pump 248 back to the tank 244 through a pressure relief valve 284. The pressure relief valve'here shown is of the balance piston type and is controlled by a solenoid operated valve 286, which valve 286 in turn controls flow of hydraulic liquid through a second by-pass 288 between the main return pipe 254 and the relief valve 234 in the conventional manner.

Fresh water is supplied to the wash and backwash pipes 46 and 64, respectively, from a suitable source of supply here indicatedas a tank 235. Specifically, a pump 292 driven by a motor 234 draws water from the tank 290 through inlet pipe 236 and discharges the same through an outlet pipe 236 which connects with branch pipes 380 and 362. Branch pipe 38!] leads to a solenoid operated reversing valve 364 which controls pipes 366 and 368 leading to the fluid motor I2 which actua'tes the backwash pipe 64. Return liquid from the fluid'motor I2 passes through the reversing valve 384 and thence through pipe Sid back to the tank 230. The other branch pipe 362 is controlled by a solenoid operated. valve H2 and leads directly to the wash pipe 46.

A. plurality of normally open mercury-type switches SI, S2, S3,,S4, S5 and S6 are closed in predetermined sequence by cams 3M, 3I6,, 3I8, 326, 322 and 324 to operate the various mech anisms of the separator in properly timed, sequential relation, and a timer motor 326 rotates the cams 3I4-32LI in unison and. at proper speed.-

its control panel'and indicates when the motor 326 is energized.

As soon as the first switch SI is closedby cam 3M, a circuit is closed through a control relay CRI, which relay is connected acrossv the power busses 328 and 336 and in series with the. switch SI by conductors'340,342, 344 and 346. Relay CR! operates two normally open switches SW! and. SW3 and a normally closed switch SW9. Switch SW! controls aconductor 348 which connects an auxiliary timing device 358 across the power busses 328 and 336. The normally closed switch SW9 also controls the conductor 332 and thus the operation of the motor 326. The purpose of switch SW8 will be hereinafter described in'detail. When relay CRI is energized, it closes switch SW7 and opens switch SW9. out the motor 326 to stop rotation of cams 3I4I This drops 2324' and cuts'in the auxiliarytimer 358 which controls the circuit for a predetermined period of time and then mechanically reverses the switches SW7, SW3 and SW9 in an obvious manner by means ofarm 35! to again start the motor 326 in operation. v

Normally open switch SW8 controls a conductor 352 which connects solenoid VI across the power busses 328 and 336 and the solenoid VI operates the reversing valve 252 which controls the charging valve 35. When switch SW6 is closed by energization of relay CRI, the solenoid VI is energized to operate reversing valve 252 and to open the charging valve 35. Sirup is then charged tot'he basket 28 continuously until the auxiliary timer 350 completes its cycle of-operation and returnsithe switch toits normal open position. Thus the basket 23 receives a predetermined charge of'sirupand crystals .for each operation of the valve 35 and'the cycleis timed so that the basket is substantially fully charged during each operationof the valve.

As: a safety feature to prevent overcharging of :the basket 20. due to changes in viscosity of the charged material or other factors, the'basket' is equipped with a float valve S lli which controls aurelay CR2 connected across the power busses 328'and 333* by a con'ductor" 354. Relay CR2 operates'a normally closed'switch SW1 inconductor 352' and a normally open switch SW12 in a conductor. 353which joins'conductors 352 and 35d. If the liquid level in the-basket 20 rises sufficiently to'operate the float valve SIB before the auxiliary timer 35D closes the chargingvalve 35, relay CR2 is energized, switchSWl l is openedand switch SW12 is closed. As soon as switch SWH opens, the circuit through solenoid" Vi is broken and the reversing valve 252 is actuated to close the charging valve 35. Simultaneously, switch SWil closes a holding circuit which maintainsrelay CR2 energized even though the liquid level in-basket 20 drops suiiiciently to open the float valve S13 and until the auxiliary timer 35B-completes its cycle of operation to return switches SW1, SW8 and SW9 to their normal positions. Manifestly, when switch SW8- is opened. by the auxiliary timer 353 the holding circuit through relay CR2. is broken and switches :SWI l and SWl2 return to their normal positions preparatory to the next operating cycle.

When the timer motor 323 is energized by closure of switch SW9, cams 3l4324 again begin to rotate. A short drainage period is. provided after the charging operation to permit the sirup to be centrifuged from the housing and cam 3l6then closes switch S2 to complete a circuit through the solenoid'V2 which is connected across the main busses 323*an-d-330 by a conductor 358. Solenoid V2 operates the reversing valve 332 which directs fluid to the motor Hill to raise the wash water housing 5|.

Shortly after switch S2 is closed cam 322 closes switch S5 to complete a circuit through solenoid V5 which is connected across the main busses 328 and 330 by a conductor 363. Solenoid V5 opens valve 312 so that water is charged to the spray pipe 46 to wash the crystals collected in basket 20. After a suitable interval, switchSB is released by cam 322 to shut off the'wash spray and the timer 323 then allows a short periodfor drainage.

At approximately the time the wash spray shuts off, cam 324 closesswitch S6 to complete a circuit through solenoid -V6' which is connected across the main busses'323 and 336 and in series with theswitch by a conductor 362. Energization of solenoid V6 opens the by-pass valve 286 so that hydraulic fluid flows in a short open circuit. As a result, pressure in the hydraulic circuit drops so that the pump Mil-and motor 242 merely idle and consume very little power.

At'the'end of the drainage period; switchSG is released by cam 224 to de-energize solenoid V6 and 1 close by-pass'valve 288 so that pressure in the. hydraulic -fluidline returns to normal. At aboutthe sametime-cam 3H5 releases switch S2 to de-energizesolenoid V2, whereby to lower the wash water housing-5l to its-normal position so that the discharge port 48 again registers with the sirup housing 50.

'Asthe'next step in'the operation cycle, cam 3'l8jclosesswitch S3 to complete a circuit through solenoid V3 whichis connected across the main busses 228 and 230and in series-with the'switch by a conductor 364. Energization of solenoid 'V3 positions. the valve I22 so that hydraulic fluid underpressure operates fluid motor 30 to'lower basket 20 whereby to discharge crystals from the basketinto the crystal housing. 63. After discharge. of the crystals is completed, cam 3l8 releases switch S3 to tie-energize solenoid V3 whereby to: return thevalve I22 to its normal position and to raise the basket 20preparatory tor-another charging operation.

At'about the time the basket 20 is fully raised, cam 3l4 again closes switch SI to repeat the cycle of operation described above. This same cycle of charge, wash, drain and discharge may be repeated overand over again entirely automatically as long as desired.

As: suggested, the: apparatus also includes means for operating the backwash pipe 64 periodically to flush away sirup and crystals which accumulate in the basket 20 below stripper 23. Since sirupand'crystals under the stripper 28 tend to impair the operating efficiency of the separator,-it is desirable that the washing operation be performed automatically after the machine has cycled a predetermined number of times. In the apparatus here shown, a selector switch Sl3 is connected'in the circuit, which selector switch controls thebackwash operation, andis manually adjustable to cause the operation-to'occur everyone to" ten cycles of the machine. In the drawing'the selector switch S23 is set to cause the backwash operation to occur during every sixth cycle of the machine.

More specifically, the selector switch S53 has two series of ten contacts each designated generally at A and'B, respectively. The contacts in each set "are "arranged in" a generally circular pattern and corresponding contacts in the two sets are electrically connected. Electrically conductive arms 3E4 and 36B are rotatably mounted to sweep respective sets of'contacts A and B. Arm 354115; manually rotatable and can be positioned to-engage any contact in the series B. On the other hand, the contact arm 335 is mechanically operatedby a pawl and ratchet 368 and 31D. Pawl 358 is-urged against the ratchet 310 by a spring 37!! and is actuated by a relay R! which is'connected across the main busses 328 and 330 and in series with switch S! by a conductor 312. Ratchet31l) rotates against the action of a spring 314, and a slidable stop bar 316 is urged against the ratchet by a spring 318 to prevent spring 314 from returning the ratchet 310 to its initial position after each operation'of pawl 365. Also, it

will bo -observed that the stop bar 375 is provided with" an upstanding lug 383 which extends upwardly-atone side of a laterally projecting pin 382 on pawl 368. This arrangement permits axial movement of pawl 338 to rotate ratchet 370 without disturbing the stop bar 316; however, the stop bar can be retracted to disengage pawl 358 from the ratchet so that spring 314 can return the ratchet to its normal position. According to the present invention, the stop bar 316 is retracted'bya' bell crank 384 which in turn is actuated by a relay R2.

Thus, it will be readily apparent that relay R! willbeenergized each time switch SI is closed, i. e., once during each cycle of the machine, and that the arm 365 will be moved one contact in a counterclockwise direction each time the relay R1 is energized. Whenarm 366 is rotated a sufiicient number of times to close a circuit through the switch S13 to arm 364, the backwashing operation is caused to occur. With the switch S13 set as shown in the drawing, the machine must cycle six times to move arm 366 from the full to the dotted line position before an electrical circuit is completed between arms 364 and 366.

According to the presentfinvention, the switch S13 is connected in the network with arm 366 electrically connected to bus 328 and in series with switch S4 by a conductor 386, and arm 364 is electrically connected to the main bus 336 by a conductor 388. Thus when arms 364 and 366 are positioned to close the circuit, current will flow through switch S13 as soon as cam 320 is rotated to close switch S4. In this connection, it will be readily apparent that switch S4 is closed once during each cycle of the machine but current does not flow through switch S13 until arms 364 and 366 are positioned to close a circuit through the switch.

' In order for switch S13 to control the backwashing operation, a relay CR3 is inserted in conductor 368, which relay has four normally open switches SW14, SW15, SW56 and SW11. Switch SW11 is electrically connected across the main busses 328 and 339 and in series with a solenoid V4 by a conductor 396. Solenoid V4 actuates the reversing valve 394 which controls fluid motor 12 for actuating and charging wash pipe 64.

Thus, relay CR3 is energized whenever switches S4 and S13 are closed and energization of the relay closes contact SW1! to complete a circuit through solenoid V4 to perform the backwashing operation. In this connection. it is to be understood, of course, that cam 32!! is positioned to close switch S4 sometime during the cycle when the basket 20 is raised.

In order to permit the switch S13 to be reset automatically after each backwashing operation, relay R2 is electrically connected to conductor 388 between switch SE3 and relay CR3 by a conductor 392 and to the main bus 339 in series with switch SW16 by a conductor 394. Also, a holding circuit is provided for relay R2 through switch SW by a conductor 396. Manifestly, energization of relay CR3 also closes switches SW15 and SW16, and closure of the latter switch energizes relay R2 to retract stop bar 3'56 and reset switch S13 in the manner hereinabove described. As suggested, closure of switch SW15 completes a holding circuit through relay CR3 so that the latter is not de-energized when spring 314 returns arm 366 to its initial position during the resetting operation.

Normally open switch SW i 4 is connected across the busses 328 and 336 and in series with solenoid V2 by conductor 396. Thus, solenoid V2 is energized to raise the wash housing 5i each time relay R3 is energized whereby the backwash water is collected in the wash housing 51 and does not contaminate sirup'in the housing 59.

In order to prevent the backwashing operation from occurring, through some inadvertence, when the basket 26 is lowered, a relay CR4 is connected in parallel with solenoid V3 by conductor 400.

Relay CR4 has a normally closed switch SW18 in conductor 388 and in series with relay CR3, thus if solenoid V3 is energized for any reason to lower housing 20 whenswitches S4 and S9 are closed,

from being completed through solenoid V4 to perform the backwashing operation.

A backwashing operation can be performed manually at any time by means of a normally closed push-button switch $19 which is electrically connected in conductor 388 and in series with switches S4 and S13 and relay CR3. Also, switch S19 is adapted to close a circuit through a' conductor 402 which is connected to bus'328 and to conductor 388 between switch S13 and relay CR3. Thus, manipulation. of switch S19 by-passes switch S4 and selector switch S13 and closes a circuit through relay CR3 to perform the backwashing operation. Switch S19 is normally positioned as shown in the drawing by spring 4114. Consequently, it must be held depressed until the backwashing operation is completed. As soon as the switch S19 is released, it is returned to its normal position by spring 494 to de-energize relay CR3.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

Having thus described the invention, we claim:

1. In a centrifuging apparatus, a rotatable,

. axially fixed stripper member; a curb ring carried by and rotatable with said stripper member;

and a basket mounted for rotation with and axially slidable on said stripper, said basket provided at the rim thereof with an inturned annular flange and said curb ring formed with an external annular shoulder which snugly fits and projects below said flange in one position of the basket, the projecting portion of said shoulder and the side wall of the basket cooperating to define a pocket below said flange; and means for draining liquid'from said pocket radially outwardly through the wall of the basket.

2. In a centrifuging apparatus, a rotatably driven centrifuge basket; a casing for receiving material centrifuged from the basket and provided with a discharge port; and separate sirup and wash housings around said casing, each of said housings being annular in form and provided with an inlet disposed in confronting relation to said discharge port, said sirup housing being stationary and normally arranged with its inlet in register with said discharge port and said wash housing being vertically movable to position its inlet in register with discharge ports and to close the inlet of said sirup housing.

3. In a centrifuging apparatus, a rotatably driven centrifuge basket; a curb ring seating against the rim of the basket and rotatable there with, said curb ring having a radially outwardly projecting portion; and an overflow housing around said basket, said housing having an inner annular wall provided with a radially inwardly extending ,fiange disposed in alignment with and' spaced circumferentially from the rim of said curb ring and provided about saidfiange with an annular inlet, whereby overflow from the basket or material charged, to the basket and falling on said curbring is thrown radially outwardly by centrifugal force from the curb ring and into said housing.

4. Ina centrifuging apparatus, a rotatably driven centrifuge basket; a curb ring seating against the rim of said basket; a housing around said basket having an internal annular partition defining concentric inner and outer chambers and said partition provided at theupper edge thereof with an inturned annular flange disposed in alignment'with and in slight circumferentially spacedirelation to theperiphery of said'curb ring; means for raising-and lowering the basket relative tosaid curb ring; and means for stripping solids from the basket upon movement of the latter" axially away from the curb ring, said stripper operable to'spill solid material over the rim of the basket and into the inner of said chambers and said inturned annular flange serving as a bafile to deflect liquidoverflowing from the basket or falling onto said curb ring into the outer of said chambers and to prevent such liquid from entering the inner chamber and contaminating said solid material.

In a centrifuging apparatus, a rotatable basket having aforaminous annular side wall; a curb ring surmounting said basket and seating downwardlyagainstthe rim thereof; a plurality of fluid actuated means each having amovable wall; and means disposed exteriorly of said basket connecting said 'movable walls to said curb ring, whereby operation of said fiuidactuated means effects independent relative movement between the basket and saidcurb ring.

6. In a centrifuging apparatus, a rotatably driven centrifugebasket having a bottom; a stripper fitting snugly within the basket and axially movable relative thereto; and means for flushing between the stripper and the bottom of the basket including a wash pipe arranged to impinge a'stream of .water upwardly against said bottom, and means associated with said bottom for collectingthe water impinged thereagainst and for discharging it into the space between the bottom and said stripper;

' 7. In a centrifuging apparatus, a rotatably driven centrifuge basket having a bottom; a. stripper member snugly fitting in said basket and movable axially relative thereto; and'means for flushing between the bottom of said'basket and said stripper including a wash pipe having a discharge outlet positioned to direct a stream of water upwardly against said bottom, and an an- I nular groove in the bottom of said basket positioned to receive said stream of water and provided with a=plurality of passages effecting communication between said groove and the space between said bottom and said stripper.

81 The combination as set forth in claim '7 wherein said groove has an outwardly and upwardly inclined outer wall portion.

9. Ina centrifuging apparatus, a basket having a bottom and a foraminous annular sidewall; a generally disc-shaped stripper member 'within said basket and peripherally engaging the'inner surface of said annular side wall; means for ro tatably driving the basket and stripper in unison; means for reciprocating the basket axially relative to the stripper; and means for flushing the spacebetween the bottom of the basket and the stripper, said means including a wash pipe having a discharge outlet positioned to direct a stream of water upwardly against the bottom of thebasket, a fiuid motor carrying said wash pipe, said motor holding the wash pipe normally lowered so as not to interfere with reciprocation of the basket but adapted to raise said pipe to position the discharge outletthereof in proximity tothe bottom of the basket, an annular groove in the under surface of said bottom positioned to receive a stream of water from said wash pipe, and a plurality of passages leadingfrom said 16 groove: to thespace: between the bottom oflthe basketiand said stripper.

10. A centrifugingapparatus comprising a centrifuge basket; a stripper within and snugly fite ting said basket; valve-controlled means for charging material tobe centrifuged to said hasket; valve-controlled means for introducing a wash liquid into said basket; means including a valve-controlled wash pipe for introducing a fiushing'liquid between the bottom of the basket and said stripper; means for rotating said basket and said stripper in unison; means for'moving said basket and'said stripperaxially relative to each other; means for operating said'valve-controlled charging means, said valve-controlled wash means, and said means for effecting relative axial movement between the basket and the stripper sequentially and in timed relation; and means for operating said flushing means automatically after said'last-mentioned means has operated a' predetermined number of times;

11. In a centrifuging apparatus, a baskethaving a bottom and a foraminous annular side wall; a generally disk-shaped stripper member within saidbasket and peripherally engaging the inner surface of said annular side wall; means for rotatably driving the basket and stripper in unison; means for reciprocating the basket axially relative to the stripper; and means for flushing between the bottom of the basket and the stripper, said means including'a wash" pipe havinga dis charge outlet positioned to direct the cleansing medium upwardly against the bottom of the basket, actuator means for said wash pipe, said actuator means holding the wash pipe normally lowered so as not to interfere with reciprocation of the basket but adapted to raise said pipe to position the discharge outlet thereof in proximity to the bottom of the basket, an annular groove in the undersurface of said bottom positioned to receive cleansing medium from'said wash pipe, andat least one passage leading from said groove to the space between the bottom and said stripper.

12. In a centrifuge apparatus, a rotatable centrifuge basket having an open top provided with an internal, annular flange, a stripper within and rotatable with said basket, means for effecting relative axial movement between the basketand the stripper, a curb ring mounted independently of the basket for sealing the rim of the basket, said curb ring being formed with a radially outwardly facing annular shoulder arranged to project into and snugly fit the internal flange of the basket and when so projected to'be spaced radially inwardly from the side wall of the latter whereby 'said shoulder and said wall define a'pocket within and immediately below the rim of the basket, said pockets having liquid discharge openings extending radially outwardly for draining liquid therefrom.

13. In a centrifuge apparatus, a rotatable centrifuge basket having an open top provided with an internal, annular flange, a curb ring mounted independently of the basket for sealing the rim of the basket said curb ring being formed with a radially outwardly. facing annular shoulder arranged to project into and snugly fit the internal flange of the basket and when so projected to be spaced radially inwardly from the side wall of the latter whereby said shoulder and said wall define a pocket within and immediately below the rim of the basket, said pocket having liquid discharge openings extending radially outwardly for draining liquid therefrom.

14. In a centrifuging apparatus; a rotatable centrifuge basket having an open top provided with aninternaLannular flange, liquid discharge openings'in said basket, a stripper within and rotatable with said basket, means for effecting relative axial movement between the basket and the stripper, a curb ring mounted independently of said basket and positioned to seat against the rim of the basket, said curb ringformed with a radially outwardly facing annular shoulder arranged to project into and snugly fit the internal flange of the basketand when so projected to be spaced radially inwardly from the latter whereby said shoulder and said wall define a pocket with-.- in and immediately below the rim of the basket,

said pocket having liquid discharge openings extending radially outwardly, for drainingliquid therefrom, the liquid discharge openings of said pocket beingsubstantially larger and offering less resistance topassage of liquids than the liquiddischarge openings of said basket.

In a centrifuging apparatus, a rotatable basket having an annular side wall, a curb ring surmounting and in sealingrelation to said basket, an actuator for raising the curb ring from the basket, and members disposed exteriorly of and the basket, and means for disengaging the curb ring from 'the basketsimultaneously with said relative axial movement including a first support means connected to and extending downwardly fromthe projecting portion of the curb ring exteriorly of the basket, 'a second support means connected to the curb ring and extending downwardly therefrom through the bottom of the basket, and means interconnecting said first and second support means for mutual operation.

17. In a centrifuging apparatus, a rotatable basket having an annular side wall, a curb ring surmounting and in sealing relation to said basket, a stripper in said basket, and means for disengaging the curb ring from the basket including means disposed ,exteriorly of the, baskets interconnecting the stripper and the curb ring.

18. In a centrifuging apparatus, a rotatable stripper member, a curb ring rotatable with said stripper member, a basket containing and 'ro-. tatable with said stripper, said curb ring and said basket being movable axially relative to each other and said basket provided at the rim'thereof with an inturned annular flange, said curb ring being formed with an external annular shoulder which snugly fits and projects below said flange in one position thereof relative to the basket, the

projecting portion of said shoulder and the side wall of the basket co-operating to define a pocket below said flange; and means for draining liquid said housings being annular in form and provided with an inlet disposed in confronting relation to said discharge port, one of said housings being stationary and normally arranged with its inlet in register with said discharge port and the other of said housings being vertically movableto position its inlet in register with said discharge port and to close the inlet of said one housing.

20. In a centrifuging apparatus, a rotatably driven centrifuge basket, a curbv ring for sealing the rim ofthe basket and rotatable therewith, and anoverflow housing around said basket, said housing having an inner annular wall and proyidedwith a radially inwardly extending flange disposed in alignment -with and spaced circumferentially from the rim of said curb ring, said housing further provided above said flangewith an annular inlet, whereby overflow from the basket of material charged to the basket. and falling on said curb ring is thrown radially outwardlyby centrifuge force from the curb ring andinto said housing. a

21. In a centrifuging" apparatus, a rotatably driven centrifuge basket, acurb ringlfor s aimg the rim of the .ba'sketand rotatable therewith, an

annular member surrounding and spaced circumferentially from said curb ring, means supporting said. annular member in substantially the same plane as the curb ring when the latter is in sealing relation with the basket, and an overflowhousingaround said basket'and said annular member having an annularinlet above said member, whereby overflowfrom the basket or. material charged to the basket and falling' on curb ring is thrown radially'outwardly by centrifugal force from the curbring and into, said housing.

22. In a centrifuging apparatus, a rotatably driven centrifuge basket, a curb ring for sealing the rim'of the basket, a housing around said basket' having an internal annular partition defining .concentricinner and'outerchambers' and said partition provided at the upper edge thereof v'z-ith an inturned annular flange disposed in alignment with and in slight oircumferentially spaced relation to the periphery of said curb ring when the'latter is in sealing relation to the basket, means for separating the basket and said curb ring, and means for stripping solids from the basket when the latter and the curb ring are sep arated, said stripper being operable to spill solid material over the rim of the basket and into the inner of said chambers, and said inturned annular flange serving as a baiiie to deflect liquid overflowing from the basket or falling onto said curb ring into the outer of said chambers and to prevent such liquid from entering the inner chamber and contaminating said solid material.

23. In a centrifuging apparatus, a rotatably driven centrifuge basket, a curb ring for sealing the rim of said basket, means for effecting relative axial movement between the curb ring and the basket, concentric inner and outer chambers around said basket, and an annular baffle extending transversely across said inner chamber and disposed in alignment with and in slight circumferentially spaced relation to the periphery of the curb ring when the latter is in sealing engagement with the basket.

24. In a centrifuging apparatus, a rotatably driven centrifuge basket, a curb ring for sealing the rim of said basket, means for effecting relative axial movement between the curb ring and the basket, concentric inner and outer chambers around said basket, an annular bafiie extending transversely across said inner chamber and disposed in alignment with and in slight circumferentially spaced relation to the periphery of the curb ring when the latter is in sealing engagement with the basket, and means for stripping solids from the basket, said stripper operable to spill solid material over the rim of the basket when the curb ring is separated therefrom under the baffle and into the inner of said chambers, said bafiie serving to deflect liquid overflowing from the basket or falling onto said curb ring into the outer of said chambers and to prevent such liquid from entering the inner chamber and contaminating said solid material.

25. In a centrifuging basket having a bottom, a stripper member snugly fitting in and rotatable with said basket, means for effecting relative axial movement between the stripper and the basket, and means for flushing between the'bottom of said basket and said stripper including a wash pipe having a discharge outlet positioned to direct a stream of water upwardly against said bottom, and an annular groove in the bottom of said basket positioned to receive said stream of water and provided with a plurality of passages effecting communication between said groove and the space between said bottom and said stripper.

26. In a centrifuging apparatus, a rotatably driven centrifuge basket having a bottom, a stripper fitting snugly within the basket, means for effecting relative axial movement between the stripper and the basket, and means for flushing between the stripper and the bottom of the basket including a liquid-supply pipe for directing liquid against the exterior side of the bottom of the basket, and means carried by the basket for collecting liquid impinged thereagainst and defining a passage through which liquid is discharged into the space between the bottom and said stripper.

27. In a centrifuging apparatus, a rotatable basket having an annular side wall; a casing surrounding and rotatable with said basket, said 20 casing cooperating with the side wall of the basket to define an annular collecting chamber for material centrifuged from the basket and provided adjacent the bottom thereof with a discharge port; a pair of annular housings surrounding said casing, each of said housings having an annular chamber provided with a bottom so as to be capable of receiving and accumulating material discharged from said collecting chamber, each housing also having an annular inlet communicating with said chamber and facing in the direction of said discharge port; one of said housings being stationary with its inlet in register with said discharge port; and means for moving the other of said housings vertically to bring its inlet into register with said port and to close the inlet of said stationary housing.

BRADLEY G. COX. THOMAS EVANS.

References Cited in the file of this patent UNITED STATES PATENTS

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