US2944657A

US2944657A - High capacity bucket elevator

Info

Publication number: US2944657A
Application number: US755729A
Authority: US
Inventors: David A Davis; Frederick L Smith; James H Snodgrass
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1958-08-18
Filing date: 1958-08-18
Publication date: 1960-07-12
Anticipated expiration: 1977-07-12

Description

July 12, 1960 D. A. DAVIS ETAL HIGH CAPACITY BUCKET ELEVATOR Filjed Aug. 18, 1958 s SheetsSheet 1 July 12, 1960 D. A. DAVIS ET AL 2,944,657

HIGH CAPACITY BUCKET ELEVATOR Filed Aug. 18, 1958 3 Sheets-Sheet 2 July 12, 1960 D. A. DAVlS ET AL 2,944,657

HIGH CAPACITY BUCKET ELEVATOR Filed Aug. 18, 1958 Z 3 Sheets-Sheet 5 FIG. 5,

. :by widening orlengtheningduring their filling operation, V

crease in the bucket .uxl

2,944,651 HIGH CAPACITY BUCKET ELEVATOR David A. Davis, Clarendon Hills, Frederick L. Smit Maywood, and 'James H. Snodgrass, Chicago, 11]., assignors to Link-Belt Company, a corporation of Illinois Filed Aug. 18, 1958, Ser. No, 755,729 5 Claims. .(Cl.198-152) This invention relates to bucket elevators, and deals more particularly with the signed to increase the material handling capacity of such elevators.

Bucket elevators are widely used in industry for lifting loose bulk materials such as coal, grain and cement from one level to another to, for example, allow its flow by gravity to points of further treatment or storage. Usually, these elevators comprise a vertical casing inside of which are one or more endless strands trained around upper and lower sprocket wheels for movement in' ascending anddescending runs. To the strands, at spaced points along the length thereof, are attached a plurality of buckets which are filled with material in the lower portion of the casing near the foot wheel, carried up the ascending run, and discharged intheupper portion of the casing near the head wheel. "5% j Under normal conditions the amount of material handled'by'a particular elevator in.a given amount oftime is determined by, and increasesdirectly with, the capacity of the individual buckets, the number of such buckets attached to a given length of rate at which they .are'carried up -the' -ascending run.

Various other considerations, however, put practical limits on the extent to which these determining factors may be increased to obtain an increase handling capacity of the elevator. a single'bucket carrying strand, for example, the buckets are commonly attached tothe strand along their rear surfaces so as toprotrude outwardlyfrom the strand. In

' those instances where these bucketsare filled by digging into a pile of material in the bottom, the casing the buckets first scoop. up .acharge of material 1 or boot, portion of and then plow through the remainder of it to the top surface of the pile. Because of the resistanceof the material in the pile, rather large forces are exertedon the buckets by. this scooping and plowing action. These forces are applied to a particular bucket in a direction generallyparallel to the strand and Iproduce a'torque in the. overall material 'In an elevator having 7 construction of a bucket depacity.

materialhandling capacityof a conventional bucket ele vator, and, more specifically to do so without jeopardizing its mechanical strength and without increasing the size of the casing required.

A more detailed object of this invention is to provide an elevator bucket having a high material capacity, fabricated as a rigid structure requiring no additional reinforcing, and adapted for connection to. a bucket carryingstrand of the elevator in a manner which minimizes the torque produced at the point of connection thereto.

1 Another object of this invention is to provide a bucket" for a single strand bucket elevator so constructed as to include material receiving pockets formed therein which extend rearwardly on either side of the strand, and which are in ope'n communication with the major portion of the bucket interior so as to increase the buckets overall ca- A further object of this invention is to provide a bucket of the foregoing character in which the rearwardly extending pocket portions thereof are each covered by a closure, or roof, member which serves to strengthen the bucket and to guide the material from the bucket during the endless strands, and the discharge in such a manner as to prevent its falling back down the casing. l

A still further object of this invention is to provide a high capacity elevator bucket of the foregoing character adapted for use in connection with either low speed gravity discharge type, or high speed centrifugal discharge type, bucket elevators, as may be desired.

Other objects and advantages of; he invention will be apparent during the course-of the following description;

Inthe accompanying drav'vings-forming apart of this j specification and in which like numerals are employed to designate like parts throughout the same,

. Figure 1 is aperspective-view of an elevator bucket embodying the present invention, a part of one side being br oken'; away" to better illustrate structural details,

about the point of connection between the bucketand the strand which tends totear the two apart. As the eifective area 'ofthebucket Whichehgages the material is increased the digging forces' and the torque :producedi therebyare accordingly increased, and, unlessfthe means for connecting the bucket and strand are correspondingly strength"- .ened; therbuckets may actually ,be torn from the strand Also, in the past an increase in' the bucket size beyond the bucket-dimensions, both thatnormally used usually required a stronger chain and advantage.

An object of this invention, therefore, is to increase the loads carried 7 'Figure 4 is a'sectional view,

' Figure 2 is a top plan view of the bucket illustrated in Fig l, p

Figure 3 is a rear elevational view of the bucket illustratedin Fig; 1, A

taken'on a horizontal plane, of a bucketembodyingthe present invention, and

illustrates an alternate method for connecting a bucket to an e'levator chain, and

Figure 5 is a sectional vlew of the upper, or discharge,

end of a bucket elevator employing buckets embodying the'present invention. a V I V In the drawings, wherein forthe purpose of illustration are shown the preferred embodiments of this invention, and first particularly referring to Fig. 5, there is shownthe upper portion of a bucket elevator. eludes a' vertically disposed casing 10 which encloses. an endless strand, such: as a chain 12, supported for movement in an ascending run 14 along one side of the casing run l6 along the other sideof the cas for the chain lz 'is provided by a head and a descending ing. ,The support wheel or'sprocket 17'rotatably mounted in'theupperpon tion of the casing 10 and afoot wheel or sprocket (not shown) mounted in the lower portion of the casing 10, aroundwhich the chain is trained. Movement of the chain'in the ascending and descending runs may beeffected by suitablemeans for driving'either the head or the foot sprocket. I l

"Tothe chain 12, at spaced points along the length hereof, are attached a plurality of buckets, 18 which,

during operation of the elevator, are filled with material 20 in the lower portion of the casing 10. The-filled buck ets are carried up the ascending run 1 4 by movementof the chain ;12 and are inverted and discharged as they pass overthe head sprocket 17, a suitable spout zg being pro- This elevator inbuckets 18 are spaced relatively'close. together along the chain 12: so as, to form a substantially continuous series of; buckets, and the manner in which the material is discharged as the buckets pass over the head sprocket 17 is shown to be that accompanying a relatively low speed operation. That is, the buckets 18 are moved at such a speed that the discharge therefrom is effected almost entirely by gravity with the material falling freely from the buckets as the latter are inverted, and being guided from the casing by the bottom portion of a preceding bucket in a manner hereinafter described. lt'is to be understood, however, that the invention also contemplates the elevator being operated at a substantially higher speed with the material being propelled from the buckets by centrifugal forces developed as a result of passing over the head sprocket 17, in which case it may be desirable to space the individual buckets 18. further apart than shown in Fig. 5.

In accordance with the invention, the buckets 18 are provided with pocket portions for increasing the material receiving capacity thereof, these pocket portions extending rearwardly from the chain and being covered by roof portions which add strength to the buckets and prevent material in the pocket portions from falling back down the casing as the buckets are inverted for discharge.

Referring to Figs. 1, 2 and 3, for a detail description of a bucket 18 made in accordance with the invention, it will be noted that the bucket includes a plurality of wall portions arranged to define a structure having a material receiving cavity 24 therein. The cavity 24 includes a first material receiving portion 26 in the forward part of the bucket. provided with an open top or mouth 27 and two material receiving pocket portions 28 in the rear part of the bucket which openly communicate with the first portion 26 and add to the overall volume of the bucket. The wall portions comprising the bucket 18 in the present instance are shown as being formed from flat stock pieces secured together by welding. It is to be understood, however, that any other suitable means for forming the wall portions could be employed, and that the bucket 18- could be formed as an, integral casting or as a weldment'of any desired material.

The wall portions defining the bucket 18, include two opposed end wall portions 30 and two spaced apart back wall portions 32 each connected at the outer end thereof to a rear edge of a respective one of the end wall portions 30. Each back wall portion 32 extends, inwardly from its associated end wall 36, toward. the other end wall, for some distance and terminates at an inner end 34 which is spaced a substantial distance from the inner end 34 of the other back wall portion 32 so as to form a gap 36 between the two back wall portions 32, the gap being located generally centrally with respect to the two end wall portions 30.

wall portion 46 is. inclined outwardly and upwardly, when viewing the bucket in an upright position as in Fig. 1, so that the under surface thereof may serve as a downwardly and outwardly directed chute or slide, when the bucket is in an inverted position, for conveying material discharged from a succeeding bucket to the spout 22 in an elevator such as illustrated in Fig. 5. Also, it is preferable that the side edgesofj the bottom wall portion 44 and front. wall portion 46 be positioned somewhatinwardly from, the edges of the end walls 3t) so that the end walls provideoutwa-rdly directed skirt portions 48 which extend beyond the lower surface of the bottom and front wall portions. The skirt portions 48, therefore, may serve as additional guides for confining the material discharged from a succeeding bucket to the chute provided by the under surfaces of the bottom and front wall portions.

The pocket portions 28, as best seen in Figs; 1 and 2, are located one on either side of the recessed portion forming the channel 42 in the exterior of the bucket. It will also be noted that each pocket portion is defined by one rear wall portion 32, part of an end wall portion 3! and a side wall portion 40:, and is covered by a. roof portion 5t)v whichis connected to the top edge of the rear wall portion 32. The, roof portion 54) extends forwardly from the rear wall portion and covers the space between the end wall portion, 30 and the side wall portion 40 associated therewith. By welding the roof portions 50to the top edges of the end wall portions 30 and side wall portions 40 between which they extend, additional rigidity for the bucketv may be obtained. Preferably, the roof portions 50 are inclined Within the gap 36 is a recessed portion of the bucket 7 defined by a medial or forward wall portion 38 spaced forwardly from the back wall portions 32 in alignment with the gap 36, and two side wall portions 4%}, each connected to the innerend 34 of a respective one of the back wall portions 32. The side wall portions 40 extend forwardly to the medial portion 38 and are; connected thereto. As seen best in Fig. 3, the medial wall portion 38 and the side wall portions 4t extend the full height of the bucket 18,, and together with the back wall portions 32 define for the bucket 18 a rear wall having a vertically extending channel 42 formed therein.

The bucket 18 also includes a bottom wall portion 44 adapted to close the lower part of the bucket, and a front: "wall portion 46 closing the forward part of the bucketandhaving an upper edge 47 defining the top of the material receiving cavity 24. Preferably, the front forwardlyv and upwardly, as illustrated in Fig. 1, from the rear wall portions 32 and are located or extended above thelevel of the upper edge 47 of the front wall portion 46, whenviewing the bucket in an upright position. If so inclined, the roof portion 50 forms a, down: wardly and outwardly inclined slide for guiding material forwardly from the pocket portions 28 when the bucket 18 is inverted for discharge. Also,lif the roof portions are located above the upper'edge 47 the pockets 32 will extend above the normal level of ,the material 'carried' by the buckets, which level is limited by the height of the upper edge 47, and will provide a covered space 52, as seen'in Fig. 5., for receiving and maintaining in the bucket a portion of the material during the first part of the bucketfs travel around the head sprocket 17, thereby preventing thematerial from falling back down the casing 10. i

Referring to Figs. 2 and 3 for a detail description of the manner in which the buckets 18 are attached to the chain 12, it will be noted that the chain is "positioned within the channel 42 defined by the medial wall portion 38 and sidewall portions 40. The chain comprises a plurality of pairs of laterallyopposed side bars 54 arranged in longitudinal alignment with adjacent ends of adjacent pairs of side bars being overlapped and joined by a transverse pivot pin 56 amending through the overlapped ends. One ofthe pairs of sidebars S4 is positioned within the channel 42 and is provided with a wing portion 58 extending laterally outwardly with respect to the chain from each of the 's'ide bars 54. The wing portions 58 are disposed forwardly of the chain and engage the rear surface of themedial wall portion 38 to which they are rigidly secured, as by bolts 60. With this form of connection" between the chain and bucket, itwill be observed that a portion of the bucket extends rearwardly beyond the point of connecace gee? An alternative method of fastening the bucket 18 to the chain 12 is shown in Fig. 4. In this construction a pair of opposed side bars 54 positioned within the channel 42 is provided with wing portions 62 extending laterally outwardly with respect to the chain formed on each of the side bars 54. These wing portions 62 are positioned rearwardly of thelchain 12 and engagethe rear wall portions 32 to which they are secured by suitable means such as bolts 64. With this arrangement it will be noted that the wing portions are located outside of the channel 42 and therefore the channel maybe being aligned with'a portion ofthe top edge of saidchann'el to providea common edge extending the full distance between the'end walls over which all of the material from the bucket cavityspills when being discharged,

made narrower than in the embodiment of Figs.'2 and 3,

on either side of the channel. a

to increase the capacity of the pocket portions disposed Referring to Fig. 5 for a description of the manner in which the buckets 18 function during discharge, it

will be noted that the material \20 fills the buckets to I substantially the level of the upper edge 47 of the front wall 46, leaving empty a covered space 52 in the upper part of each of the pocket portions 28. As a bucket rounds the head sprocket 17 the front wall 46 thereof is tipped upwardly with respect to the rear portion of the and. mean's for fastening the buckets to their chain links I with the latter positioned in said rear wall channels.

bucket causing the material to shift toward the rear portion of the bucket as its angle of-repose is exceeded. I In; stead of escaping from the bucket, however, the shifting material fills the empty covered spaces '52 and is main: 7

tained in the bucket during the initial part of its inversion. By the time the bucket reaches a position at which 2. A bucket elevator asdefined in claim 1 further characterized by the bottom surface of the front wall of each bucket being inclined in the direction of travel of the chain link to which the bucket is attached so that said bottom surface will serve as a chute for the material spilled over the said common edge of the next succeeding bucket.

3. A bucket elevator as defined in claim 2 further characterized by the bottom edge portions of the end walls extending beyond the said bottom surface of the front wall to serve as guides for the material-moving over the chute formed by said bottom surface.

4. A bucket elevator as defined in claim 2 further characterized" by the roof portions covering the said pockets being inclined in the same direction as, and arthe material will'fiow therefrom it is 1 so located with respect to the preceding bucket that the material discharged falls onto the latter bucket, and is subsequently guided forwardly by the under surfaces of the bottom and front walls of the preceding bucket to the chute 22. The paths followed by portions of the material in a bucket during the various phases of its discharge are indicated generally by the dashed arrows of Fig. 5. s

It is to be understood that the forms of this invention herewith shown and described are to be taken as preferred examples of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention 7 or the scope of the subjoined claims.

Having thus described the invention, we claim:

1. A bucket elevator comprising an endless chain formed of pivotally connected linkssupported by a head sprocket for movement in vertical ascending and descending runs, a plurality of closely positioned buckets at tached to the links of said chain and adapted to discharge after passing the top dead center of the head sprocket, each of said buckets having end, bottom, front ranged in parallelism with, said bottom surface of the front Wall so that the inside surfaces of the roof portions of each bucket will be arranged in the same plane as the bottom surface of the front wall ofthe next preceding bucket while the buckets are moving in said vertical runs. s

5. A bucket elevator as defined in claim 1 further characterized by wing portions formed on the chain links to which the buckets are attached, and means for fastening said wing portions to the innermost portions of the said rear wall channels so that the weight of the material conveyed in the pockets of the buckets will be po- 7 sitioned onthe opposite side of the point of connection of the'buckets to their chain links than the weight of the material conveyed in the main portions of the bucket cavities.

References Cited in the file of thisv patent UNITED STATES PATENTS Dowling July 25, 1911 .Harrison Sept. 8, 1914