US2298182A - Vibrating screen - Google Patents

Description

Oct. 6, i942. H, L STRUBE 2,298,182

' VIBRATING SCREEN Filed Nov. 25, 1939 5 sheets-sheet 2 I l", v v (u E I l WI I L III.

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H. L. STR'UBE VIBRATING SCREEN Y 5 Sheets-Sheet 3 Filed Nov. 25, 1939 Oct. 6, 1942. H. L. sTRuBE.

VIBRATING SCREEN Filed Nov. 25,y 1 939 5 Sheets-Sheet 5 Patented ocr. e, 1942 i I c '2,298,182

UNITED STATES PATENT OFFICE vmRATmG `SCREEN Harry Louis Strube, Philadelphia, Pa., assgnor to y Link-Belt Company, a corporation ot/Illinols- Application November 25, 1939,*Serial No. 306,171

i 7 Claims. (Cl. 209-243) This invention relates to new and' useful imquirements during certain periods. The volume provements in vibrating screens which, although of mud will vary considerably, depending upon not necessarily so limited, are particularly adaptthe depth of the hole and the speed of operation ed for use in reclaiming rotary mud employed of the pumps. Near the surface, where the presin oil well drilling operations. sures are not great, the volume ls large, while at Vibrating screens have been found to be exthe lowerlevels, where the pressures are high, tremely valuable in separating the rotary mud the volume decreases considerably.

from the sand, shale, borings, etc., which are (b) High surges, when the mud is likely to carried by the mud to the top of the well. Prior spurt out beyond the discharge end of the screen to the use of such screens, it was the practice to 10 and become lost in the tailings of sand, borings, discharge the mud with its foreign matter from shale, etc.' the top of the well casings into ditches and large (c) Completely shutting off the llow of mud storage ponds to permit the sand, shale, borings, to the screen when itbecomes necessary to make etc., to settle out of the mud. This old method repairs, etc.

required the use of a considerable quantity of (d) Properly distributing the ilowof mud evenexpensive special mud,'much of which could not 1y across the entire width and throughout-the be reclaimedfor reuse. Also, large pieces of solentire length of the screen so as to take full adids and the like would not always settle and convantage of the available screening area.- sequently were pumped back through the drill (e) Hook-ups where the mud is delivered to pipe into the well, causing rapid wear of the the feed chute of the' screen at an angle instead pump parts, etc., and frequent jamming of the of head on. drill bit. (f) Relieving or protecting the expensive.

The use of vibrating screens for reclaiming the screen cloth from excessive and rapid wear at the rotary mud eliminates practically all of the zone where the mud, with its highly abrasive forabove mentioned disadvantages because; eign matter, is delivered to the screen. (1) It quickly and` completely removes from It is a primarybbject of this inventionfto prothe mud all of the sand, shale, boring, etc., parvide self-contained or unitized vibrating screen ticles which are not small enough to pass through structures which are particularly adapted for rethe mesh of the screen and permits the mud to claiming rotary mud for immediate reuse and be immediately recirculated for use. which will perform in an extremely eilicient man- (2) It avoids much wearing of the pump parts ner under all the working conditions encountered and jamming of the drill bits. in the different oil fields.

(3) It reduces the amount of costly rotary Afurther important object is to provide vbratmud required for drilling a well to about oneing screen structures which will adequately take half of that which was v needed when settling care of all fluctuations, from maximums to minponds Were relied upon to effect separation. imums, in the volume of mud delivered thereto (4) It speeds up the sinking of the well .by maduring complete rotary drilling operations. terially reducing the number. of shut down pe- Another object ofthe invention is to provide riods during drilling operations, thereby greatly simple, compact, andV effective means for regu# reducing thev costs. 40 lating the volume of mud delivered to the screen Of course, there have been some refinements cloth; for completely stopping the flow when reand structural modifications incorporated in conpairs are needed; for distributing the mud, either ventional vibrating screen structures to adapt uniformly or at different volumes, to the entirel them to this use of reclaiming rotary mud. width of the screen cloth, regardless of the angle Such revamped screens, however, are not capable at which the mud is delivered to the feed chute of performing in the most efficient and economiof the screen, and for controllingv the portion or cal manner under all of the different working point in the length of the screen clothat which conditions encountered in different oil elds, unthe mud will be delivered, regardless of the v01- der different hook-up arrangements, and during ume of mud being fed to the screen. the drilling of a complete hole on any installation. A Still another object of the invention is to pro- For example, prior screens are inadequate to fulvide a vibrating screen structure having means ly and electively take care of or provide for: for protecting the expensive screen cloth from ex- (a) Fluctuations in the volume of mud de- Cessive and rapid wear at the point' or points livered to the screen during a complete` drilling Where the mud, with the highly abrasive foreign operation, or as a result of unusual operating rematter mixed therewith, is discharged ont@ the of vibrating cloth and which will additionally make available for use a greater portion of the length of the screening area, than has been possible heretofore., l i

'on' or insisten uniuzed ,vibrating triictu which will provide'formaximum economyi fii'r'fiiiice during a complete drininesperadosfbca'ss io'ff the vpor-.sundry f of 2empioyirrg i'eitn'er'v tnefiennrevavauabie screening, arearhfrtheiunitfrvhenithe volum:` of mud .is high-.

, Itmust be although the vibrating screen structures embodying this invention' have for their primary object the reclaiming of rotary mud, they also `are capable ofr reclaiming other liquida-or semi-liquids, which must be screened before, being reused.

Other objects and advantages of the invention.

Still.' d ofbipt ','offthe invention is the or ai; iractionalzdmrtianfzefl .saidtarew textile fibei'lzemainderf when the substantially U-shaped bracketJ-whiohfis formed-withsides of unequal lenstmtmprovide ari-,inclined .top portion will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate Vlike parts throughout the same, l

Figure 1 is a side elevational view of one f 'orm of vibrating screen unit embodying this invention,

Figure 2 is a top plan view of the unit disclosed in Fig. 1,

Figure 3 is anendl elevational view of the unit shown inFigs. 1 and 42, taken at the inlet or receiving end of the device,

. Figure 4 is a Vdetailperspective View of a plate which functions as a support and closure seat for a plurality of inlet gates embodying this invention,

Figure 5 -is a `detail perspective view of one inlet gate to-be associated with the plate of Fig. 4,

Figure 6i is alfragmentary, detail perspective view of a perforated feed plate 'and its associated feed chute.

Figure 7 is a top plan' view of amodifled form Figure 8lisfan'endelevaticnal view of the unit disclosed "i-n- Figf' 'andttaken at the inlet end offthe unit, and

Figure 9 isa fragmentary, side elevational view of thefinlet portiongof, the unit disclosed in-Figs. 7and'8. l

In the drawings, wherein for the purpose o f illustration are'shwnthe preferred embodiments of' this invention, and particularly'referring to Figs. lfto 3,"-inclusive, thescreen structure of thesex figures is entirely self-contained or unitizedand is adapted to be moved readily from y place to place. For thatreason, the base of the unit includes a pair of vskidsIII which are formed of angle iron stock. rI'hese skids are braced relative to each other and are interconnected at one end by an angle ironII.l dicularly from'this angle `iron bracing member II are the angle iron bracketmembers I2 which are of. invertedl'Ir-shapei in side elevation. Extendingbetwenand secured to the horizontally arranged4 arm portions I3, formed by the upper parts ot these bracket` members I2, are horizontally extending@aigle irons I4. These angle irons Il xtendlaterally in opposite directions from the bracket arms I2 and are interconnected attlieir outer, parallel 'ends by the brace members I5 and II.` The'bracing member I6 takes the Extending perpenformof a square or rectangular plate which acts 20. flThesebrackets I9 function-as supportsfor the vibrating screen box which is mounted on the inclined top portions 20.

y'I'he screen box consists of the side frame members 2I which are suitably braced relative toeach other by any desired, conventional form of transverse bracing means, not disclosed. Each one of these side frame members 2I is provided with a laterally outwardly projecting top flange 22 which act as mounting anges for the screen box. A screen cloth 23 is stretched between these side frame members 2| and is secured thereto in any desired, conventional manner, such as by means of the usual removable clamping plates.

Each side of the screen box is yieldably supported by a leafspring member, generally designated by the reference character 24. The constructionandvmode of operation of these supporting leaf spring members is fully disclosed and described in my Patent No. 2,141,320, issued December 2'7, .1938. It will be unnecessary, therefore, to describe these members in detail. It should be sufficient to state that the generally horizontally extending bottom portion 25 of each spring is bolted to the inclined top portion 20 of a bracket I9 withaI spacer plate 26 interposed therebetween. One of the leaves of the spring, in

the illustrated example the top leaf,` is provided with upstanding, bowed end portions 21 which have their extremities bolted to brackets 28 which are attached to and extend laterally of the side frame members 2| of the screen box. These brackets provide a substantial anchorage for securing the springs to the side frame members of lies the top flange 22 to brace'and support the same.

This bracing and supporting of the top flanges 22 of the side frame members 2I is found to be desirable to provide means for attaching the mounting brackets 30 which support the opposite end portions of an out-of-balance vibratory device 3I which functions'to produce the desired vibrating movement of the screen box. This vibratorydevice has a double-grooved pulley I2 mounted on one end of its shaft. This pulley has trained thereover the V-belts 33 which extend to and are trained `over the double-grooved pulley 34 mounted'on theshaft of the electric motor I1. Figs. 1, 2, and 3 disclose the motor and vibratory device drive being located at one side of the entire vibrating screen unit. It is to be understood, however, that this drive mechanism may be located at either side of the unit, depending upon the particular requirements of any installation.

Supported from the transverse brace members Il is a feed lchute which is designated in its entirety by the reference character 35 and is best illustrated in detail in Figs. 1, 2, and 6. This feed chute receives the mud to be treated from a suitable wooden sluice 35', see Fig. 1, andincludes upstanding end plates 36 which are joined at their lower edges by a bottom plate 3l.l plate includes a blank portion 36 and a. perforatedl portion 39 having elongated perforations 40 formed'therein.

in the drawings may be employed as desired. The bottom portion 38 andv the end plates l36 function as a feed chute for the screen. The perforated portion39 is of novel construction and overlies the receiving endportion of the screen cloth. These manner spreads over the cloth and acts as a protective, cushioning layer where the main pormud, containing the the screening surface and to prevent the mud from splashing over the sides of the screen box.

Another extremely novel feature of construction incorporated in this improved vibrating screen unit consists of a distributing and flow or volume controlling arrangement which is best illustrated in Figs. 1 to 5, inclusive.v This mechanism includes a plate 42 of substantially Z-shape CIIv the cloth and the point at which the main body of the mud is delivered onto the scgee'ningzsurface. These inlet gates are capable' of .effecting this desired distribution and control of .the flow side at which the mud is concentrated.

inclined arrangement function to direct the Due to the downwardly of the inlet gates, they will mud downwardly onto the screen. They, therefore, will prevent the mud from spurting out beyond the discharge end of the screen when a large volume of mud is being delivered to the feed chute, or during high surges of delivery. Of course, all of theinlet gates can be completely closed or seated against their supporting plate 42 for entirely shutting off the feeding of mud to the screening surface. This will enable repairs to be made to the screen when necessary.

Arranged beneath the screen box is a mud colg lecting tank or hopper 52 which is of proper size in end elevation or vertical section. This plate x includes a vertically arranged main body portion 43 having oppositely extending top and bottom flanges 44 and 45, respectively. The top flange 44 is suitably secured, as by welding, to the adjacent transverse bracing member I4, see Figs. 1 and 2. The bottom flange 45 is suitably secured, as by welding, to the bottom plate portion 38 of the feed chute 35, see Fig. l. The main body portion 43 of this plate is provided with a suitable number of substantially rectangularly shaped inlet openings 46.

Fig. 5 discloses in detail a form of inlet gate which is provided for each one of the openings 46. This gate includes a main body portion 41 which is of greater area thanthe area of the opening 46 with which it is to be associated. Each perpendicular edge ofthe body portion 41 is provided v with a right angularly arranged flange 48. Each flange is formed to provide an apertured ear 49 at its upper end. Fig. 4 discloses the inlet plate 42 as having a pair of ears 50 arranged at the side of each inlet opening 46. Hinge pins, or the like, 5|, see Fig. l, are employed for securing the apertured ears 49 of the gates to the pairs of apertured ears 50 of the mounting plate 42. This type of mounting for the gates permits them to be moved into any desired angular relationship over an arc of approximately 90 degrees. When these gates are in their truly vertical position, they engage the main body 43 of the mounting plate 42- and completely close off or cover their respective inlet openings 46.

It will be appreciated that these inlet gates 41 provide extremely effective means for controlling the volume of mud being discharged onto the screen cloth as a whole and each section thereof; the distribution of the mud across the width of ments. New

and shape to receive and collect all of the mud passing through the screen cloth 23. This tank terminates in a trough portion 53 which is clearly illustrated in Figs. 2 and 3 as being adapted to discharge to either or both sides of the vibrating screen unit. Discharge at one side of the unit is closing the remaining opening off the screened mud.

Figs. 7, 8, and 9 disclose a modified form of vibrating screen unit from that disclosed in Figs. l to 6, inclusive. This unit of Figs. 7 to 9 differs from the previously described unit principally by having its screen box arrangement divided into separate and distinct parts which are independently vibrated and for that reason are capable of being entirely independently operated. Because of this fact, the unit of Figs. 7 to 9, inelusive, may be operated in its entirety and have a capacity equal to that of the unit disclosed in Figs. l to 6, inclusive, or its capacity may be reduced to that of one section or part of this unit as one section or part may be operated while the remaining section or part remains idle. When operating in this manner, the unit will have a capacity which is only one-half that of the first described unit, or only one-half of its own complete capacity. Notwithstanding these two screen boxes, this unit employs only one feed chute, one mud collecting tank with its two-way discharge trough, and one prime mover or electric motor. As many features of construction of this modi fied unit are the same as those disclosed and described in detail in connection with the unit illustrated in Figs. 1 to 6, inclusive, the same reference characters will be applied to identical elereference characters will be applied to and a detail description will be given for only such elements as differ structurally from those of the first described unit.

In this dual screen arrangement, the screen Byvarying the extent fof boxes are @ach provided with the side frame members 2Ia which have their top mounting flanges 22a. Brackets 28a extend laterally from each side of both of the screen members and A have connected thereto the upper extremities of members 24 are mounted on the fourbrackets I9 by being connected lto the top portions 20 of these brackets. Out-of-balance vibratory units 3lare arranged one on each screen box and are secured to the top flanges 22a of the screen side frame members by mounting brackets a. The shaft of each vibratory unit Sla projects at the inner end of theunit and is provided with a pulley 32a over which is trained a belt 33a. These twol belts are trained over pulleys 34a mounted on the shaft ofthe motor I1 which is carried by a base plate 55 suitably secured to the top wall 56 of the feed chute 35a. Although Figs. '1 and 8 disclose the motor l1 as being arranged at one side of the center line of the complete vibrating screen unit, it will be understood that the motor may be shifted -to the other side of. the center line if so desired. By disengaging either one of the belts 33a from its pulleys 32a and 34a, the vibratory unit 3Ia'driven by this belt will be rendered inoperative and its associated screen box will remain stationary. It will be appreciated, therefore,l that a considerable saving in power, wear, and tear may be obtained,

when the volume of mud being-fed to the securing unitis such that one'screen section will be capable of handling the same. Y

The feed chute 35a, receiving mud from a wooden sluice 35', is supported by upstanding angle irons 51 which extend upwardly from the transverse brace member il which extends between the two skids I0. Additional braces 58 are provided for supporting the overhanging portion of the chute 35a, see Figs. 8 and 9. A platform 59 is illustrated in Fig. 9 in side elevation and in Fig. 8 in end elevation as underlying the feedchute 35a for supporting the same. The top or platform 56 of the feed chute is attached at its rear end to the flared side walls 60 of the feed chute. The forward portion of this motor platform or chute top 56 is supported by elements which will be specifically described at a later point.

It will be noted by inspecting Figs. 7 and 8 that the feed chute 35a flares out from a comparatively narrow inlet end to a discharge end which includes both of the screen boxes. This spreading out or flaring of the feed chute is provided by the side walls 60 which diverge relative to ea'ch other and terminate in truly parallel side Wall sections 6I, see Fig. '1. Fig. 8 discloses a perpendicular plate 62 which bridges the space between the two screen boxes. This imperforate plate in effect closes a portion of the discharge end of the feed chute 35a. The bottom of this chute is formed by a feed plate which includes a blank portion 38a. This feed plate portion terminates in two perforated portions 39a which overlie the respective screening surfaces and are provided with perforations 40a. This structure functions in the same manner as the perforated portion 39 of the feed plate disclosed and described in connection with the preceding ilgures.

Extending between each outer side wall portion Il of the feed chute and the adjacent vertical edge of the bridge plate $2 is an inlet gate mounting plate 42a. si-Each one of these inlet gate mounting plates .42a is of identical construction with the mounting plate 42 disclosed in Fig. a but is of reduced length and has a smaller number Vof inlet openings 46a formed therein. The bottom flange of each one of these inlet plates is secured to the bottom wall portion 38a of the inlet chute. The top flanges 44a of these plates 42al and a top. flange $3 of the bridge plate I2 provide the aforementioned transverse v,support for the forward portion ofl Vthe motor platform 56.

The inlet gate plates 42a have mounted thereon the inlet gates i4, see Figs. 7 and-9, which are of identical construction with the inlet gatesvdisclosed in detail in Fig. 5. These inlet gates 64, therefore, will not be described in detail. It is to be understood that the inlet gates 64 perform the same functions for their respective screen boxes as the inlet gates 41 of the screening unit illustrated and described in connection with Figs. 1 to 3, inclusive. 'These' inlet gates for the dual screen units will function to uniformly distribute the mud throughout the width of their respective screen cloths and will direct the mud down onto these cloths so that it will not spurt beyond the discharge ends of the screens. By shutting or closing all of the inlet gates for one of the screen units of this dual arrangement, that particular screen box will' not receive any of the mud delivered to the comi' plete vibrating screen assembly and the screen box which remains in communication with the feed chute will receive all of the mud delivered to the complete assembly. l

A single mud collecting tank or hopper 52a is provided and is of proper size and shape to receive the reconditioned or reclaimed mud from both of the screens. This collecting tank or hopper terminates in a single discharge trough 53a which has its opposite ends left open at 54a for discharge to either side of the vibrating screen unit into a discharge chute 54', see Fig. 8. Either outlet opening may be closed by means of a cover, not shown, so that discharge of the reclaimed mud will occur at only one side of the complete unit. Of course, screened mud may be discharged from both outlets by leaving them both open.

Although the drawings and the'speciflcation only disclose and describe the use of electric lmoy tors 'I1 for driving the vibrating devices for the screen boxes, steam turbines, gasoline engines,

and other types of prime movers may be and frequently are used instead of electric motors where they are found to be more practical on certain installations'. Also, I do not desire to have the novel structural features and their very desirable operations limited in use to screen boxes which are mounted for vibratcry movement on leaf springs for other kinds 4of mounting may be employed. My invention, furthermore, contemplates the use of other types of vibrating devices for the screen boxes than the unbalanced shaft units which are disclosed. For example, the vscreen boxes may as readily be vibrated by eccentrics, differential motions, electric solenoids,4

against the plate to completely stop the flow of'` departing from the spirit of the invention or the scope of the subjoined claims. h

Having thus described the invention, I claim:

1. A vibrating screen comprising a screen box mounted for vibratory movement and including a screening surface, a feed chute for delivering the material to be treated partially overlying the receiving end of the screening surface, means formed in the bottom of the chute for delivering a portion of the material onto the part of lthe screening surface underlying the feed chute to utilize said underlying surface and also to provide a cushioning layer of material serving to protect the portion of the screening surface ar ranged beyond the chute from the abrasive action of the remaining major portion of the ma terial which is discharged from the end of the chute, and means in the feed chute and positioned with respect to the said delivery means in ,the bottom of the chute and the discharge end of the chute for either completely stopping or controlling the volume of flow of material through both the delivery means and from the discharge end of the chute and for deflecting the material that flows from the discharge end of the chute downwardly onto the aforesaid portion of the screening surface which is provided with said protective cushioning layer of material. 2. A vibrating screen comprising a screen box, including a screening surface, mounted for vibratory movement, a feed chute for delivering the material to be treated partiallyv overlying the receiving end of the screening surface and having its bottom plate apertured for delivering a portion of the material onto the part of the screening surface underlying the feed chute to utilize said underlying surface and also to provide a cushioning layer of material serving to protect the portion of the screening surface arranged beyond the chute from the abrasive action of the remaining major portion of the material which is discharged vfrom the end of the chute, and means in the feed chute and positioned with respect to the said delivery apertures in the bottom of the chute and the discharge end of the chute for either completely stopping or controlling the volume of iiow of material through both the said delivery apertures and from the discharge end of the chute and for deflecting the material that flows from the discharge end of the chute downwardly onto the aforesaid portion of the screening surface which is provided with said protective cushioning layer of material.

3. A vibrating screen comprising a screen box, including a screening surface, mounted for vibratory movement, a feed chute for delivering the material to be treated partially overlying the receiving end of the screening surface, means' formed in the bottom of th'e chute for delivering a portion of the material onto the part of the screening surface underlying the feed chute to utilize said underlying surface and also to provide a cushioning layer of material serving to protect the portion of the screening surface arranged beyond the chute from the abrasive action of the remaining major portion of the material which is discharged from the end of the chute, a vertical plate extending transversely of the feed chute upstream of the delivery means and having a plurality of outlet openings formed therein, and a control gate for each outlet opening mounted on said plate for pivotal movement about a transverse axis, each gate being of proper size to'close its outlet opening when lying flatly material through the delivery means and from the end of the feed chute and being swingable into different inclined positions relative to the plane of the` plate for varying the volume of material flowing through its opening below the said pivotal axis, for varying the head of the material flowing past the said delivery means in the bottom of the chute to control the amount of material passed through said delivery means, and for deflecting the material that flows from the discharge end of the chute downwardly onto the aforesaidportion of the screening surface which is provided with said protective cushioning i layer of material.

4. A vibrating screen comprising a screen box, including a screening surface, mounted for vibratory movement, a feed chute for delivering the material to be treated partially overlying the receiving end of the screening surface and having its bottom plate apertured for'delivering a portion of the material onto the part of the screening surface underlying the feed chute to utilize said underlying surface and also to provide a cushioning layer of material serving to protect the portion of the screening surface arranged beyond the chute from the abrasive action of the remaining major portion of the material which is discharged from the end of the chutea vertical plate extending transversely of the feed chuteup'strearn of thel `delivery apertures and having `a plurality of outlet open-ings formed-therein, and a control gate for each outlet opening mounted onsaid plate for pivotal movement about a transverse-axis, each gate being of proper size to close its outlet opening when lying flatly against the plate to completely stop the flow of material through the delivery means and from the end of the feed chute and being swingable into different inclined positions relative to the plane of the plate for varying the volume of Vmaterial owing through its opening below the said pivotal axis, for varying the head of the material flowing past the said delivery apertures in the bottom of the chute to control the amount of material passing through said delivery apertures, and for deflecting the material that flows from the discharge end of the chute downwardly onto the aforesaid portion of the screening surface which is provided with said protective cushioning layer of material.

5. A vibrating screen comprising a frame, including a base portion and an upstanding portion at one end of vthe base portion, said upstandingv portion being provided with vertical side members and a horizontally arranged top portion between the side members, a screen box, having a screening surface, supported for vibratory movement on the base portion and arranged to have its receiving end underlie the said horizontal top portion, a feed chute mounted on yand reinforced by the vertical side members and the horizontal top portion of the frame, said feed chute being arranged to partially overlie and deliver material to be treated to the receiving end of the screening surface and having its bottom plate apertured for delivering a portion of the material onto the part of the screening surface underlying the feed chute to utilize said underlying surface and also to provide a cushioning layer of material serving to protect the portion of the screening surface lying beyondthe discharge end of the chute from the abrasive action of the remaining major portion of the material which is discharged from,the end of the chute,

a vertical plate extending transversely of the feed chute upstream of the delivery apertures and having a plurality of outlet openings formed therein, and a control gate for each outlet opening mounted on said plate for pivotal movement about a transverse axis, each gate being of proper4 size to close its outlet opening when lying atly against the plate to completely stop the flow of material through the delivery means and from the end of the feed chute and being swingable l0 into different inclined positions relative to the plane of the plate for varying the volume of material flowing through its opening below the said pivotal axis, for varying the head of the material flowing past the said delivery apertures in the bottom of the chute to control the amount of material passing through said delivery apertures, and for deflecting the material that ows from the discharge end of the chute downwardly onto the aforesaid portion of the screening delivering material to said surface, said device comprising a chute having a bottom plate and two upstanding side plates cooperating with the bottom plate to define an outlet end, said bottom plate having means formed therein and arranged to discharge a portion of the material passing through the chute downwardly in advance of and in a substantially parallel relation to the outlet end edge of the bottom plate, and means in the feed chute and including a plurality of independently pivotal gates for either completely stopping or varying the volume of flow of material' passing through different transverse portions of the discharge means and the end of the chute and for controlling the distance to which the material may be discharged beyond the outletend edge of the bottom plate to take care of variations in volume and velocity of flow of the material.

7. A material feeding device adapted to be associated with a vibrating screening surface for delivering material to said surface, said device comprising a chute having a bottom plate and two upstanding side plates cooperating with the bottom plateI to dene an outlet end, said bottom plate having apertures formed therein and arranged to discharge a. portion of the material passing through the chute downwardly in advance of and in a substantially parallel relation to the outlet end edge of the bottom plate, a vertical plate extending transversely of the feed. chute upstream of the delivery apertures and having a plurality of outlet openings formed therein, and a control gate for each outlet opening independently mounted on said plate for pivotal movement about a transverse axis, said gates and transverse vertical plate cooperating to eithercompletely stop or vary the volume of flow of material passing through different transverse sections of the chute below the said pivotal axis and for controlling the distance to which the material may be discharged beyond the outlet end of the bottom plate to take care of variations in volume and velocity of flow.

HARRY LOUIS STRUBE.

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