US2592917A - Plansifter - Google Patents

Description

April 15, 1952 J. F. LOCKWOOD ET AL 2,592,917

PLANSIFTER Filed April 8, 1947 4 Sheets-Sheet l Jm. A

|. k J k libv'elzrboz a April 15, 1952 J. F. LOCKWOOD ET AL PLAN-SIFTER 4 Sheets-Sheet 2 Filed April 8, 1947 I-i I 120v enters eflT'Loalcwoaei/ April 15, 1952 Filed April 8, 1947 J. F. LOCKWOOD ET AL 2,592,917

PLANSIFTER 4 Sheets-Sheet 3 April 15, 1952 J. F. LOCKWOOD 'ET AL 2,592,917

PLANSIFTER Filed April 8, 1947 4 Sheets-Sheet 4 fi' (9. .ZZZLZJ Q7. FL ()(ZLKJ/UOOdJ U -Q (13} w. A I A, 7

Patented Apr. 15, 1952 PLANSIFTER Joseph Flawith Lockwood and John Stephen Ball, 'Qheadle Heath, England, assignors to Henry Siinon Limited, Cheadle Heath, England, a

British company Application April 8, 1947, Serial No. 740,023

' In Great Britain April 26, 1946 6 Claims. 1

The present invention relates to a plansiftermachine of the type comprising a plurality of superposed sieve frames in a casing or main frame and which receive a rotary or gyratory motion so that all points on the perforated sieving covers of the sieve frames describe a circle in a horizontal plane. In machines of this character the oversized particles, hereinafter referred to as tails, pass over the marginal edges of the sieve frames and the particleswhich pass through the perforated sieving covers, hereinafter called throughs, are collected on imperforate trays disposed horizontally and spaced below the sieving covers and the throughs are conventionally discharged through ducts at the sides of each sieve frame or through a center opening which runs lengthwise of the sieving surface. In conventional machines the tails and/or the throughs may be diverted for resifting by one or more of the sieves lower down in the superposed stack of sieve frames or they may constitute the finished product and be delivered through suitable passages constituting discharge ducts.

Conventionally in machines of the character referred to the sieve frames are provided with openings at one or bothends of the sieving surface to permit the passage of tails to either the subjacent sieve or to a discharge passage where thetails constitute the finished product of the particular stock treatment.

It is readily seen, therefore, that according to the desired stock treatment and the plan flow of the tails and throughs relative to the various sieve frames in the machine conventional arrangements provide sieve frames of different length and embodying different arrangements of the openings therethrough. In some of the prior art devices providing for side delivery of the throughs the sieve frames are fitted within a box or casing and the vertical passages for the discharge of the finished product are in the side wall of this box or casing, therefore being inthe superposed sieve frames thus shortenin sieving surfaces. r It is therefore apparent that with known types -of plansifters providing for a stable duct system it is necessary, to utilize different size sieve trays in different levels of the machine and therefore to accommodate flows of stock through the ma-- .chine the. sieving surface is not utilized to the best advantage; particularly where throughs are being diverted to lower sieve frames in a stack or nest of frames for resifting. It is also clear that with known constructions the disposition of the ducts or passages being inward of the outer walls of the plansifter casing or frame and relatively inaccessible provide areas within the body of the machine itself which constitute internal passages where moths or other pests and insects can accumulate.

Therefore it is an object of the present invention to provide a plansifter machine in which the component parts thereof are standardized and interchangeable. It is further an object to provide a machine in which the duct system is so disposed as to be readily accessible and in which the stock treatment is such that all of the throughs and tails are discharged relative to the sieving frames at one end thereof.

It is a further object to provide a stable duct system readily lending itself to accommodate different plan flows of stock with a minimum of modification.

The invention therefore comprises the combination with the main casing or frame which includes side walls and supporting ledges of a plurality of similar sieve frames supported on the ledges in superimposition and which sieve frames each include a perforated cover on one face, an imperforate bottom plate on the opposite face, a vertical passage provided by a gap between the cover and one end of the sieve frame and which gap extends substantially throughout the width of the frame and a discharge opening for the space between the cover and the bottom plate constituted by a tunnel or gap provided in the end wall of the frame opposite the vertical gap and which latter gap constitutes a throughs discharge opening which extends for about one half the width of the frame. The main casing structure includes, of course, side walls of greater length than the length of the sieve frames and at one end of this casing structure a stable vertical @ductsystem is provided. This end is the end adjacent all of the throughs discharge openings of tute a pair of vertical passages respectively communicating through suitable openings with the throughs discharge openings in the sieve frames and the space between the sieve frames to recharge duct for the treated stock. Suitable switches or diverters are provided'in the side by side ducts and diverting means are provided in the outermost duct which is provided with openings in the inner wall thereof communicating with the side by side ducts and which diverting means direct the stock to final discharge spouts or outlets. The vertical opening in each sieve frame can be closed by a removable cover so that when some openings are closed and some open the stock is diverted so that tails from the superjacent sieve frame pass to the subjacent sieving cover.

Referring to the accompanying explanatory drawings:

Figure 1 is an elevation and Figure 2 a plan view showing a plansifter in accordance with this invention.

Figure 3 is a sectional elevation on the line 3-3 of Figure 2 and Figure 4 a sectional elevation on the line t-4 of Figure 2.

Figure 5 is in the part marked A a sectional end elevation on the line 5-5 of Figure 3 and in the parts marked B a sectional elevation on the line 5--5 of Figure 3.

Figure 6 is a detail plan view of a sieve frame as used in the plansifter.

Figure 7 is a sectional view on the line 7-7 of Figure 6.

Figure 8 is an end view of the sieve frame looking from right to left in Figure 6.

Figure 9 is a pictorial view of part of the end of a section of the plansifter with parts broken away to illustrate the travel of the stock through the machine.

The plansifter comprises as usual a number of sections such as a, h, c, d, e and f mounted in a frame or which is supported from above by flexible canes h, the whole being given a movement in a small horizontal circle in the known manner.

The stock is fed into the machine through the feed spouts z and leaves the machine through the spouts 7'. Suction for carrying away dust is applied to the machine through the branches k.

Certain parts of the machine which are of known construction and which operate in the manner usual in plansifters such as the sieve cleaning brushes and the crank for giving the horizontal circular motion to the machine have been omitted for the sake of clarity.

As shown in Figure 2 each" of the sections of the plansifter includes side walls respectively designated a, b", c, d, e, f, g, and h, which as noted are of greater length than the space to be occupied by the sieve frames. Along one side of the machine as indicated the vertical duct system, described in detail hereinafter and including the passageways u, v and a: formed by the walls s, t, w and y, in Figures '3 and 4, in cooperation with the outer portion of the aforementioned side walls of the sections, is provided.

As shown in Figures 6, 7 and '8 all of the sieve frame utilized with the machine are similar in design and construction and include a perforated sieving cover m mounted on a frame n which is nested within an outer frame it" which can constitute the main sieve frame. At one end of this outer frame it an opening 0 extending the full width of the sieving frame is provided by disposing a partition bar 0' transversely of the main sieve frame. The axis of this opening 0 is vertical and as seen in Figure 7 the tops of the side bars of the main frame 12 are at a greater heighth than the partitioning bar 0' and the adjacent end frame bar 0" to accommodate a removable closure or cover denoted by the reference character .2 in Figure 3, this cover resting on the tops of the bars 0- and 0 and between the side bars of the frame n. An imperforate bottom plate or tray m is provided to receive material passing through the sieving cover m. The end of the main sieving frame n opposite to the end embodying the vertical opening 0 is provided with a throughs discharge gap or opening 2) which as seen in Figure 8 extends approximately over one half the width of the end wall q of the main frame denoted generally by n and is positioned beneath the sieving cover with its axis transverse to the axis of the opening 0 so that all stock that passes through the sieving cover of each sieve frame is discharged through the opening 10. As indicated in Figure 7 blade springs r are provided for supporting the main sieve frame.

As indicated in Figure '2 the end of each section of the pl'ansifter adjacent the end of the sieve frames embodying the discharge opening .or tunnel 39 includes a vertical wall s extending transversely of the sections and between the section side walls ab", b'c, 0'11 and a similar .arrangement with respect to the sections d, c and A second series of vertical walls 10 is provided and which walls are arranged similarly to the walls s but spaced outwardly thereof with respect to the longitudinal axis of each section. A vertically disposed partitionedwall t is mounted between the walls s and w and extends perpendicular to the plane of each of these walls so that the space between the walls s and w is divided into two side by side vertical ducts m. and v. The wall denoted generally by y, in Figures 3 and 4, spaced outwardly by the wall to cooperates with the respective side walls of the sections' and the outer face of the wall 10 to provide an outermost series of vertical ducts at.

There are openings 10 in the wall s in line with the gaps or tunnels p which constitute discharge openings in the several superposed sieve frames (see Figure 4) and these openings 10 enable the material delivered through the gaps or tunnels p to pass into the vertical duct 1) which is the throughs duct for material which has passed through all the sieve covers m of the sieve frames. At certain predetermined levels in the walls s and w of the vertical duct 12 are openings as at H and i2 and these in conjunction with switch or diverter baffles as l3 can be used to return "throughsfrom a higher level in the duct 22 back into the sieve frames for re-treatment or to deliver the throughs into the vertical delivery space a. In Figure 4 all the switches l3 deliver throughs back to the lower sieve frames for re-treatment.

It will be appreciated that the switches l3 can be reversed in position to divert the grain to the channel :1: or back to the sieve frames as required.

The walls 3 and w are similarly provided with gaps Ill, H and I2 for the overtails (see Figure 3) which passover the end of a sieve cover so that such overtails can either be returned to lower sieve covers for retreatment or diverted to the delivery space w by the switches 43. As shown alternate switches return the overtails for retreatment in lower sieve frames and the others divert the overtails from above into the delivery space so.

The parts B of Figure 5 show various arrangements of divisions in the space a: for delivering the material diverted thereto by the switches 13 in the spaces u and v, to various delivery spouts, 7'. In the section of Figure 5, there are three deliveries of overtails by the openings H into three separate divisions of the space at. In section (1, there are three deliveries of throughs by the openings into three separate divisions of the space a. In section e, there are two deliveries of overtails and one of throughs into the three separate divisions of the space 0:. In section f there are two deliveries of throughs and one of overtails into the three sections of the delivery space a.

In Figures 3 and 4 the grain flow is indicated by the arrows. In Figure 3, it will be seen that the gap 0 in the sieve frames is sometimes open and sometimes closed in order to direct the grain as desired.

In the right hand portion of Figure 9, it will be seen that the throughs from the three uppermost sieve frames are returned by the switch [3 for i e-treatment and then after re-treatment are delivered by the lower switch l3 through the gap I! into the vertical delivery space :12. In the left hand portion of Figure 9 which deals with the overtails, the uppermost switch 13 causes retreatment of the overtails from above whilst the next switch lower down delivers overtails through the gap 1! into the vertical delivery passage.

There are two further switches 13 which are causing the overtails from sieve frames to go back to lower frames for re-treatment.

It will be seen that the overtails are discharged over one half of the width of a sieve at the same end as the throughs are discharged through a gap or tunnel in the sieve frame extending over the other half of the width of the sieve. It will be seen also that there are two vertical channels in each section of the machine, one behind the other at the same end of the sieve frames and that the vertical channel nearer to the sieve frames is divided by a vertical partition t into two sections it and 'v, u for overtails and v for throughs, whilst the other vertical channel is suitably divided up as shown in Figure 5 for the discharge of the various grades of the finished products.

It will be appreciated that the sieve frames are supported on suitably spaced ledges in the various sections.

We have found by experiment that owing to the gyratory nature of the motion of the sieves, both throughs and tails can be satisfactorily discharged each over one half only of the width of the sieve cover, without either the stock holding up in the blanked off corners of the sieve frame, or reduction in the effectiveness of the sieving surface.

Our improved construction by eliminating side and centre channels is very compact and simple and it enables a great variety of products to be obtained with the use of standard sieve frames. Also the discharge spouts of the machine can be arranged in a row along the side of the machine, which facilitates inspection of the products and collection below the machine. As the throughs always pass to an end of the sieve frame for discharge or transference to a lower sieve, we utilise the sieving surface more eificiently and avoid the use of spreader trays for the throughs and also eliminate any inaccessible internal or centrally disposed vertical passageways which conventionally constitute areas where moths and other pests can accumulate.

It will be understood that openings as H and [2 in the division walls s and w are positioned or provided in positions to give the grain under treatment a desired course through the machine to suit the character of the grainand the end products desired.

What we claim is:

1. A plansifter of the type receiving gyratory motion in a horizontal plane for effecting discharge of stock including a casing structure and at least one group of superposed horizontally arranged sieve frames, said frames being supported in spaced parallelism with respect to each other and said casing structure including side walls confining the sieve frames and of a length greater than the sieve frames, a vertical end wall extending transversely of and between the side walls adjacent one end of the superposed sieve frames, a second vertical end wall in parallelism with said first mentioned wall and positionedoutwardly thereof, a partition wall positioned between and extending transversely of the first two mentioned end walls and said three walls together with the side walls exteriorly of the sieve frame defining two adjacent vertical ducts, an additional wall extending parallel to said first two mentioned end walls in spaced relation thereto and outwardly of the second mentioned end wall and between the side Walls and cooperating with the same to define a third vertically disposed duct, each sieve frame including a perforated sieving cover having a total length less than the length of the sieve frame, the area of the sieve frame outwardly of the sieving cover providing an opening having a vertical axis, an imperforate bottom plate incorporated with the sieve frame in spaced relation to the sieving cover and substantially coextensive in length therewith and constituting a surface to receive material passing through the sieving cover, the end of said sieve frame opposite to the end embodying the vertical opening having an opening therein the axis of which is transverse with respect to the axis of the first mentioned opening and which second opening extends transversely with respect to the longitudinal axis of the sieve frame for a substantial portion of the width of the sieve frame subjacent the sieving cover and constituting an extension of the bottom plate to provide a discharge opening for stock that has passed through the cover, all of said sieve frames being disposed with the said discharge opening of the respective frames in vertical alignment and adjacent the said first mentioned end wall of the casing, said wall having openings therein extending transversely thereof in alignment with at least some of said discharge openings, and communicating with one of said adjacent vertical ducts, additional openings in said first mentioned end wall on the opposite side of said partition wall extending transversely of said first mentioned end wall and in alignment with the space between the sieving cover of some of the frames and the bottom plate of immediately superjacent frames whereby stock that passes over the frames passes through the said last mentioned openings into the duct adjacent thereto which constitutes a tails receiving duct and stock that passes through the covers discharges through the discharge openings in the frames and thence into the other of said adjacent vertical ducts constituting a throughs receiving duct, openings in said third mentioned end wall in communication with the respective adjacent throughs and tails receiving ducts, and removable means for selectively covering the vertical openings of at least some of the sieve frames to prevent direct vertical passage of stock through all of the sieve frames and for diverting the stock for passage selectivel either over or through the sieve cover of the frame, the gap of which is closed.

2. A plansifter of the type receiving gyratory motion in a horizontal plane for effecting discharge of stock including acasing structure and at least one group of superposed horizontally arranged sieve frames, said frames being supported in spaced parallelism with respect to each other and said casing structure including side walls confining the sieve frames and of a length greater than the sieve frames, a vertical end wall extending transversely oi and between the side walls adjacent one end of the superposed sieve frames, a second vertical end wall in parallelism with said first mentioned wall and positioned outwardly thereof, apartition wall positioned between and extending transversely of the first two mentioned end walls and said three walls together with the side walls exteriorly of the sieve frame defining two adjacent vertical ducts, an additional wall extending parallel to said first two mentioned end walls in spaced relation thereto and outwardly of the second mentioned end wall and between the side walls and cooperating with the same to define a third vertically disposed duct, each sieve frame including a perforated sieving cover having a total length less than the length of the sieve frame, the area of the sieve frame outwardly of the sieving cover providing an opening having a vertical axis, an imperforate bottom plate incorporated with the sieve frame in spaced relation to the sieving cover and substantially coextensive in length therewith constituting a surface to receive material passing through the sieving cover, the end of said sieve frame opposite to the end embodying the vertical opening having an opening therein the axis of which is transverse with respect to the axis of the first mentioned opening and which second opening extends transversely with respect to the longitudinal axis of the sieve frame for a substantial portion of the width of the sieve frame subjacent the sieving cover and constituting an extension of the bottom plate to provide a discharge opening for stock that has passed through the cover, all of said sieve frames being disposed with the said discharge opening of the respective frames in vertical alignment and adjacent the said f rst mentioned end wall of the casing, said wall having openings therein extending transversely thereof in alignment with at least some of said discharge openings, and communicating with one of said adjacent vertical ducts, additional openings in said first mentioned end wall on the opposite side of said partition wall extending transversely of said first mentioned end wall and in alignment with the space between the sieving cover of some or" the frames and the bottom plate of immediately superjacent frames whereby stock that passes over the frames passes through the said last mentioned openings into the duct adjacent thereto which constitutes a tails receiving duct and stock that passes through the covers discharges through the discharge openings in the frames and thence into the other of said adjacent vertical ducts constituting a throughs receiving duct, openings in said third mentioned end wall in communication with the respective adjacent throughs and tails receiving ducts, adjustable deflecting means positioned in both of said adjacent ducts for selectively directing tails and throughs either into the outer duct or back between adjacent sieve frames or on to sieving covers of other frames for further sifting, and removable means for $3193? tively covering the vertical openings of at least some of the sieve frames to prevent direct vertical passage of stock through all of the sieve frames and for diverting the stock for passage selectively either over or through the sieve cover of the frame, the gap of which is closed.

3. A plansifter of the type receiving gyratory motion in a horizontal plane for efiecting discharge of stock including a casing structure and at least one group of superposed horizontally arranged sieve frames, said frames being supported in spaced parallelism with respect to each other and said casing structure including side walls confining the sieve frames and of a length greater than the sieve frames, a vertical end wall extending transversely of and between the side walls adjacent one end of the superposed sieve frames, a second ver ical end wall in parallelism with said first mentioned wall and positioned outwardly thereof, a partition well positioned between and extending transversely of the first two mentioned end walls and said three walls together with the side walls exteriorly of the sieve frame defining two adjacent vertical ducts, an additional wall ext-ending parallel to said first two mentioned end walls in spaced relation thereto and outwardly of the second mentioned end wall and between the side walls and cooperating with the same to define a third vertically disposed duct, each sieve frame including a perforated sieving cover having a total length less than the length of the sieve frame, the area of the sieve frame outwardly of the sieving cover providing an opening having a vertical axis, an imperforate bottom plate incorporated with the sieve frame in spaced relation to the sieving cover and substantially coextensive in length therewith and constituting a surface to receive material passing through the sieving cover, the end of said sieve frame opposite to the end embodying the vertical opening having an opening therein the axis of which is transverse with respect to the axis of the first mentioned opening and which second opening extends transversely with respect to the longitudinal axis of the sieve frame for a substantial portion of the width of the sieve frame subjacent the sieving cover and constituting an extension of the bottom plate to provide a discharge opening for stock that has passed through the cover, all of said sieve frames being disposed with the said discharge opening of the respective frames in vertical alignment and adjacent the said first mentioned end wall of the casing, said wall having openings therein extending transversely thereof in alignment with at least some of said discharge openings, and communicating with one of said adjacent Vertical ducts, additional openings in said first mentioned end wall on the opposite side of said partition wall extending transversely of said first mentioned end wall and in alignment with the space between the sieving cover of some of the frames and the bottom plate of immediately superjacent frames whereby stock that passes over the frames passes through the said last mentioned openings into the duct adjacent thereto which constitutes a tails receiving duct and stock that passes through the covers discharges through the discharge openings in the frames and thence into the other of said adjacent vertical ducts constituting a throughs receiving duct, openings in said second mentioned vertical end wall in communication with the respective adjacent throughs and tails receiving ducts, adjustable deflectin means positioned in both of said adjacent ducts for selectively directing tails and throughs either into the outer duct or back between adjacent sieve frames or on to sieving covers of other frames for further sifting, and stationary defleeting means in said outer duct for deflecting and segregating tails and throughs falling through said duct, separate discharge spouts receiving the segregated tails and throughs from said outer duct, and removable means for selectively covering the vertical openings of at least some of the sieve frames to prevent direct vertical passage of stock through all of the sieve frames and for diverting the stock for passage selectively either over or through the sieve cover of the frame, the gap of Which is closed.

4. A plansifter of the type to which gyratory motion is imparted, including a main frame and a plurality of series of superposed horizontally arranged sieve frames, the sieve frames being incorporated in parallel groups and the main frame including means defining compartments accommodating the respective groups, and for each group of sieve frames a main frame structure including means to support the sieve frames in vertically spaced superposed relationship, spaced parallel side walls extending outwardly of the sieve frame, a vertical end wall extending transversely of the longitudinal axis of the sieve frame, positioned adjacent one end of the superposed sieve frames and between the said side walls, a second vertical end wall in parallelism with said first mentioned wall and positioned in spaced relation to said first mentioned wall, outwardly thereof and between the side walls, a third partition wall positioned between and extending transversely of the first two mentioned end walls, said three walls together with the side walls defining two adjacent vertical ducts, and an additional wall extending parallel to said first two mentioned end walls in spaced relation to, outwardly of the second mentioned end wall and between the side walls and cooperating with the same to define a third vertically disposed duct, each frame including interconnected side and end bars and a transversely extending partitioning bar disposed inwardly of one of said end bars, a perforated sieving cover extending from said partitioning bar to the opposite end bar on one face of said frame and an imperforate bottom plate extending from said partitioning bar to the opposite end bar, in spaced parallelism with respect to said sieving cover and constituting a surface to receive material passing through perforations in said cover, the area comprised between the partitioning bar and the adjacent end bar and the two side bars constituting a gap the axis of which is vertical when the sieve frame is in position, and the opposite end bar having an opening therein the axis of which is transverse with respect to the axis of said gap and saidopening extending transversely with respect to the longitudinal axis of the sieve frame for a substantial portion of the width of the frame and subjacent the sieving cover and constituting a discharge opening for material that has passed through the cover, all of said frames being disposed with the said discharge opening of the respective frames in vertical alignment and adjacent the said first mentioned vertical end wall, openings in said first mentioned wall in alignment with at least some of said discharge openings, additional openings in said first mentioned end wall on the op- 10 posite side of the said partition wall and providing communication between the space between the sieving cover of some of the frames and the bottom plate of immediately superjacent frames whereby material that passes over the frames passes through said openings into the duct adjacent thereto and material that passes through the covers discharges through the discharge openings into the other duct, openings in said second vertical end wall in communication with the respective ducts, adjustable deflecting means positioned in both of said side by side ducts for selectively directing tails and throughs either into the outer duct or back between or onto the sieve frames for further sifting, stationary deflecting means in said outer duct for deflecting and segregating tails and throughs falling through said duct, said outer duct constituting a final discharge duct, and removable means for selectively covering the gaps of at least some of the frames to prevent direct passage of material through all of the aligned gaps and diverting the material for passage either over or through the sieving cover of the frame, the gap of which is closed.

5. A plansifter of the type receiving gyratory motion in a horizontal plane, for discharging material and including a casing structure embodying spaced side walls and sieve frames sup ported in superposed spaced relation between said side walls, each of said sieve frames including opposite ends and faces, said frame having an opening adjacent one end thereof, said opening having a vertical axis, a perforated sieving cover on one face and an imperforate plate on the opposite face spaced from said cover, both said cover and plate extending from adjacent said opening to the opposite end of the frame, the said opposite end of the frame having an opening therein extending transversely of the longitudinal axis of the frame and providing a discharge for material passing through the perforated cover during gyration, all of said sieve frames being positioned with the said transversely arranged discharge openings in vertical alignment and said casing structure including wall means defining separate side by side vertical ducts adjacent the ends of said sieve frames having the discharge openings therein and wall means defining a vertical duct extending the width of the sieve frames outwardly of said first mentioned side by side ducts, one of said side by side ducts having openings therein receiving material discharging through at least some of the discharge openings in the ends of the sieve frames and the other of said ducts having openings therein receiving material discharging over the tops of at least some of said sieve frames, removable means closing the vertical openings through at least some of the sieve frames for preventing direct passage of material through all of the sieve frames and thereby selectively diverting material for passage either over or through the sieving cover of the frame, the opening of which is closed, material diverting means in both said side by side ducts and said outer duct having openings communicating with each of said side by side ducts and cooperating with said material diverting means and receiving material diver-ted there by for discharge through said outermost duct.

6. A plansifter as defined inand by claim 5 in which said material diverting means comprises selectively, adjustably positioned deflecting elements having inclined upper surfaces in each of said side by side ducts and the opening in said outer duct communicating with at least some of 12 UNITED STATES PATENTS said deflecting elements whereby material passes Number Name Date from the respective side by side ducts either back 249,998 Rider 22, 1881 into the space between superjacent sieve frames 755 073 Sturtevant et aL Man 22 1904 or onto the sieving cover of some of the sieve 5 758907 Fraser 81; a1 May 1904 frames or into the outer most duct for discharge. 884:660 Hoover Apt 1908 1,011,196 He 6 D c. 2, 1911 JOSEPH FLAWITH LOCKWOOD- 1,298,558 Fair Mgr. $5, 1919 JOHN STEPHEN BALL- 1,368,047 Neal Feb. 8, 192 1 2,159,549 Cecka May 23, 1939 REFERENCES CITED FOREIGN PATENTS The following references are of record in the Number Country Date Great Britain May 11, 1937 file of this patent: 465 636

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