GB2123374A - Twin-belt elevator - Google Patents

Abstract

A twin-belt elevator 8 comprises a load-supporting first belt 10 the operative run of which is formed and divided into a load-accepting region 16 and an elevating region 18 by a spring- loaded pivotally-mounted lower support roller 15 of a load-retaining second belt 12 positioned for co- operation with the elevating region 18 of the first belt. This co-operation is encouraged by having the load- retaining run 22 of the second belt shaped into a concave delivery region by a top support roller 24 of the first belt. The roller 15 is free to rise and fall and/or pivot. <IMAGE>

Description

1 GB 2 123 374 A 1

SPECIFICATION

Twin-belt elevator The present invention relatesto elevators, and in particularto belt-type elevators providing the combination of a horizontal loading region with thefacility to elevate atsteep inclination to a discharge location located forwardly of the loading section.

This dual purpose combination is difficuitto achieve using simpleflat belts because of the problem of forming the necessary---concave"bend in thetransition region of the beitfrom horizontal conveying to elevating in a mannerwhich does not hinderthe operation of the elevator. Thus, known proprietary dual purpose belt-type elevators, such asthe Scholtz ---Flexowell-(RTM) elevator, Numec's--- LargeCapacity Belting" and the Ace Vulcanising "Hywall" elevator, each comprise two flexible side walls set in from the edges of a cleated base belt so as to leave a narrow strip of base belt along the outside of each wall. This construction enablesthe concave bend in the base beitto be formed by mounting two narrow rollers above the belt so thatthey contactthe upper surface of the two edge strips. In operation, the material to be elevated will be wholly contained between the two flexible side wal Is. Without the side walls, the material would tend to spill into the side regions of the elevator and foul on the rollers.

It is an object of the present invention to provide a dual pu rpose belttype elevator of comparable or better performance than those currently available, but by a simpler and therefore cheaper means.

According to the present invention, a twin-beit elevator comprises a load-supporting first belt having 100 an elevating region which co-operates with the elevating region of a load-retaining second beitto conveythe load to a discharge location positioned forwardly of the load-accepting region of thefirst belt, the operative run of thefirst belt being formed and 105 divided into said elevating region and said load accepting region by a lower support roller means of the second belt.

The term -roller means- in this context is to be broadly interpreted as including any rotary device or 110 number of devices extending or spaced across the width of either beitto provide a rollertype support for the belt.

Atwin-belt elevatorfor conveying letters and packets over a C-shaped path has been proposed in French Patent Specification 647597. However, this earlier document neither suggests nor discloses the concept of using a twin-belt elevatorfor discharging to a location positioned forwardly of the load-accepting region even though this will be the desired elevator configuration in the vast majority of cases. It is significanttoo, that up to now, no such arrangement had been proposed during the fifty years or so since the French Patent Specification was published.

The French device is also deficient in other respects.

Forexample,the belt-supporting roller defining the entranceto the elevating section has only a limited degree of freedom of movement. This meansthat changes in the load being conveyed towards the elevating section will often result in a significant amount of roller displacement along the load-accepting belt away from the intended position of the roller. This in turn will lead to generally undesirable variations in the performance characteristics of the eleva- tor. This general lack of precision is aggravated by the use of a slack length of the load-retaining beitto control the passage of the load towardsthe elevating section.

Returning nowtothe elevatorof the present invention, according to a preferred feature,the roller means is carried on a pivotally-mounted support on which it is spring-loaded towardsthe adjacent region of thefirst belt. Providing the roller meanswith two degrees of freedom in this way reduces the tendency forthe roller meansto be displaced along thefirst belt in responseto a changed load on the belt. Thusthe division between the load-accepting and elevating regions of thefirst belt is maintained as constant as possible and as a result variations in the performance characteristics of theelevatorwith changing load are reduced.

Conveniently, the second belt is keptfairly taught around the roller means sothatthe entranceto the elevating section of the elevator is accurately defined bythe position of the roller means. This enables the advantage of having a spring-loaded roller meansto be exploited tothefull.

Conveniently, the roller means comprises a relatively large diameter roller, ortwo or more rollers, arranged to shapethe operative run of thefirst belt gradually inthe region of directional change.

Where two or more rollers are used, these may, if desired, be mounted on a frame which is itself pivotally attached to the pivotal ly-mounted support. In a variation of this latter arrangement, only the frame pivots.

Conveniently, the spring loading of the roller means is adjustable, a single adjustment changing the tension of both belts.

In first embodiments of the invention, the two belts are supported on as few rollers as convenient so as to encourage the belts to self-tension and self-adjust. This enablesthe belts to accommodate, compact and sandwich the conveyed material. In addition, it allows the elevatorto be constructed as a relatively lightweightclevice.

In second embodiments of the invention, the co-operating regions of the two belts are instead urged together by spring-loaded rollers orthe like e.g.

arranged to make these regions follow a zig-zag path.

Preferably, the load-retaining run of the second belt is guided about a top support roller of the first belt so as to shape said load-retaining run into a concave delivery region which encourages good co-operation between the second belt and the elevating region of thefirst belt and ensures thatthe material being conveyed is firmly gripped.

In a preferred embodiment, the inclination of the elevating and load retaining regions of the belts is adjustable, so thatthe conveyor can, without modification, offer horizontal conveying plus elevating at a range of angles.

If desired, the second belt can overhang the top end of the first beltto some extent so as to predetermine the trajectory of discharge of material from the 2 GB 2 123 374 A 2 elevator. Alternatively, at the delivery end of the elevator, the run of the first belt may projectfurther than the run of the second belt thereby to help reduce the amount of stray material emanating from the underside of the stream of material being conveyed.

It will be appreciated thatthefirst and/or second belts may each be flat or cleated as desired. Conve niently, both belts are cleated belts having the cleating spanning different transverse regions of the two belts so that marginal speed differences between the two 75 beltswill not cause interference between the cleats at the elevating region of the elevator nor prevent a degree of troughing from being achieved.

Conveniently, the two belts are of the same or roughly the same width.

Conveniently, the elevator includes troughing means effectiveto impart a trough-like shape to the elevating region of the elevator.

Conveniently, the elevator includes spillage preven tion means arranged to flank orsurround thefirst and 8F second belts atthe elevating region of the elevatortu discourage spillage of conveyed material from this region.

Conveniently, the elevator includes spillage prevc.-.

tion means arranged to flank or surround the first anc-, 90 second belts atthe elevating region of the elevator'a discourage spillage of conveyed material at this region and also to support at least in partthe two belts atthis region in such a way as to impart a trough-like shapetothe elevating region of the elevator.

A convenient spillage-prevention means, which car also serve asthe main structural member, is a tube or other hollow section surrounding or substantially surrounding thefirst and second belts atthe elevating region. In one such case, the spillage prevention means comprises a three-section device having a centre section surrounding or substantially surround ing the co-operating runs of thetwo belts atthe elevating region of the elevator and two outersections surrounding or substantially surrounding the return 105 runsofthetwo beltsatthat region.

Alternatively, the spillage prevention means may comprise a single-duct shroud inwhich all the belt runs are accommodated. One advantageofthis isthat sufficient slack belt is readilyobtained if theshroud is 110 to befolded by means of a hinge parallel tothe cross-sectional planes of the belts.

If desired,the belts may besupported onfree wheeling rollers each arrangedto keep apartthe forward and return runs of an associated beltandto derived drivefrom contactwith both said runs.

Conveniently, the elevating region of thefirst belt leadsto an extension region provided either bythe first beltor by a third belt.

Conveniently, the inclination oftheextension re gion is adjustable.

Embodiments of the invention will now be de scribed, byway of example only, with reference to the accompanying drawings in which:- Figure 1 shows a partially diagrammatic side view of 125 an elevator according to the present invention; Figure 2 shows a similar view of an alternative embodiment; Figure 3 shows a cross section of a modified belt arrangement for use either in the embodiments of 130 89 9E Figures land 2 orin those of the later Figures; Figure 4 is a partially diagrammatic side view of another embodiment of the invention and Figure 5 is a section taken along line A-A in Figure 4; Figures 6,7 and 8 are partially diagrammatic sectioned side views of further embodiments of the invention; and Figure 9 is a partially diagrammatic plan view of a conveyor assembly incorporating a twin belt elevator in accordance with the present invention.

Thus referring firstto Figure 1 of the drawings, a dual purpose elevator8 according to the present invention comprises first and second belts 10, 12 co-operating over an elevating section 14 as shown.

G this end, the be!. supporting roller 15 atthe bottom 1 - - Pippe; belt 12 is so positioneG as to shape the 'jprriose run of lower belt 1 C.. so as to divide this run.nto a mcad accepUng region 16 and an e;evating -egior, h 3. Similarly, the load retaining run 22 of uppe..jei 12 m's slightly deformed nearthe delivery region by ek ge intrusion of he top support roller 24 for belt 10 so as to encourage a proper co- operation between the two bells overthe elevating section 14 and to compact the crop stream finally immediately priorto delivery.

The belt supporting arrangement is completed by idling rollers 26,28 for belt 10 and by a top roller 30 for belt 12. it is an advantage of this design thatthere is no need for a rigid memberto space apartthe upper and ho-wer rollers of the load retaining belt.

In operation, thetop rollers 24,30 provide the drives forthe two belts, and conveniently they comprise identical diameter rollers driven atthe same speed from a common powersource (not shown).

In practice, the load accepting region 16 of belt '1 0 10G may receive its]Gad 32 in one of a number of ways e.r,,.

from a hopper I.notshown). In this latter case, to reduce zhe risi, 3f iaoses, -the- hopper arrangement would prelerabiy js sucii-i asto prevent material frorr, being deposhec, cui'Lo the edges of the belt.

In a modificatitj,- noi shown),troughing means can be incorporated, wing the elevating region 18 of belt 10 so asfurthertri.p-duce the possibility of losses. Alternatively or additionally, closelyfitting vertical side plates covering the interface of belts 10 and 12 along the full length of the elevating section 14 may be provided to contribute to the prevention of spillage of conveyed material atthe sides. If the side plates are inclined towards each other along their length at their lower edges, they will also serve the purpose of giving the upwardly inclined belt regions 18 and 22 a trough shape and general support.

As shown in Figure 1, the large diameter roller 15 at the lower end of belt 12 is spring loaded by a pair of compression springs 33 so as to allowthe belts 10, 12 to self-tension and self-adjust. This enables the two belts to accommodate, compact and sandwich material reaching elevating section 14from loading region 16. In more detail, each end of the rollersupport shaft 34 is anchored in an associated sleeve unit 36which is urged along a respective rod 38 bythe compression spring 33. Attheir lowerends,the rods 38 are secured to a common sleeve or pivot rings 40 allowing pivotal movement of the rods about an axle or pivot pins 42 secured relative to the elevator framework (not shown). The axle or pins 42 may be located wherever 3 GB 2 123 374 A 3 is convenient, provided that the loading by springs 33, either alone or in combination with additional springs (not shown), produces the required tensions in the belts 10, 12 and maintains the desired shape of the elevator.

If desired, the roller suspension linkage 33,34,36,38 may be of alternative design so thattension springs can be used.

Preferably, roller 15 is of a width equal to or greater than the two belts 10, 12. The largerthe diameter of the 75 rollerthe more readilywill bulky materials be accepted intothe elevating region, even in circumst ances of uneven feeding.

Where a more gradual changetothe elevating section is desired, e.g. to accommodate specific 80 materials, more than one rollerjoined together in the shape of a "bogey" may be used. One such arrange ment is shown in Figure 2 where the bogey 44 replaces the single roller 15 of the earlier embodiment. As will be seen from the drawing, in the illustrated embodi85 ment, bogey 44 comprises four relatively small diameter rollers 46joined together by a common support means 48 in such a way as to definethe desired curvature forthe two belts. Support means 48 is pivotally connected at 50 to the sleeve unit 36 of the suspension linkage 33,34,36,38 already described with reference to the first embodiment of the inven tion. The pivoted bogey arrangement provides an additional degree of freedom atthe intake region (acting on the principle of a sluice) and this assists in 95 the acceptance of intermittent, severely fluctuating and bulky loads.

In operation of the elevators described above, as material arrives atthe roller means provided by roller 15 or rollers 46, as the case maybe, the roller means 100 rides up over the material and sandwiches it between the two belts, springs 33 maintaining belt tension at a] 1 times. Thereafter, the material is trapped and elevated bythe upwardly inclined regions 18,22 of the belt, to be discharged at the top end of the elevator e.g. into a 105 container (not shown).

As illustrated, the upper of the two drive rollers 30 can overhang the lower drive roller 24to some extent.

Not only does this allow the trajectory of material discharge to be predetermined but it also helps to maintain the sandwiching effect at the top of the elevator if and when. large lumps of material cause the two belts to part at the lower end of the elevator.

Fora given trajectory, the throw of the material can be altered by regulating the speed of the two belts.

In a modification, extra reach for delivering the conveyed material at relatively slow belt speeds can be achieved with the elevator8 by incorporating additional rollers 52 and 54 and extending the lower belt run atthe delivery end as shown by broken line 56 120 in the drawing.

If desired, optional extension 56 may also be pivoted about roller 24to extend the vertical reach of the elevator. In a variation of this latter embodiment, roller 54 is driven instead of roller 24 and the linkage for roller means 15,44 is modified so thatwhen the vertical reach of the elevator has been extended as above described, the elevating section 14 can be pivoted about roller 28 (to the left in Figures 1 and 2) to enable material deliveryto be achieved to points located overthe feed region of the elevator.

If desired, a separate cleated or uncleated belt unit of variable inclination and speed can be incorporated in place of the integral belt extension 56to achieve a greater range of delivery of the conveyed material.

Changes in the direction of delivery can be achieved by incorporating instead an impel ler-th rower, optionally rotatable about a nearvertical axis.

In an alternative method of operating the illustrated embodiment, instead of driving roller24 (or 54) and roller30, only one of these rollers is driven, the co-operation between thetwo belts overtheir elevating regions being adequateto move that one of the two belts which is notdirectly in contactwith the driven roller.

Referring nowto Figure4and 5,these showan embodiment having much in common with the above described embodiments, the principal difference being that the belts 10, 12 are now enclosed by a three-section shroud assembly 62 (shown only in Figure5).

Apartfrom preventing spillage of the material being conveyed, the illustrated shroud provides guides and safety protection forthe return runs 64,65 of the two belts, so that better control and compliance with safety regulations is achieved.

The side walls of shroud 62 are removably attached to the central shroud members as indicated bythe flanges 67, thereby allowing endless belts to be inserted into and used in the assembly.

The broken lines atthe top and bottom of the shroud corss-section shown in Figure 5 areto be inperpreted as indicating thatthe outer sections of the shroud need not be fully closed provided that, as shown, the side panels have flanges of sufficient width to guidethe return runs of the belts adequately. However, if desired, full horizontal panels may be provided, particularly atthe top of the shroud, to fully or more fully enclose the belts and thereby increase weather protection.

It should be made clearthatthe optimum size and/or shape forthe centre section of the shroud will depend on the throughputs and types of material to be used. For example, instead of the shape shown in Figure 5, the centre section might be circular or diamond-shaped or olive- shaped in cross-section if this were thought desirable better to help contain the load in the elevating sections of the belts.

Returning nowto Figure 4, the various belt- engaging rollers illustrated are preferably cyclindrical or crowned, inconformity with normal practice, to assist tracking. Of the two belts present, only the lower belt 12 is driven and this from the lowermost roller 26. The upper belt 10 moves by frictional contact with the lower belt or the materia I being conveyed.

With this in mind, the lower roller 15 of the upper belt is arranged to be spring-loaded, as is the upper roller 30 of the lower belt. Movement of both these spring-loaded rollers is limited to the clearance existing within the centre section of the shroud assembly.

An angularly adjustable deflector 69 atthe delivery end of the conveyor is desirable at high belt speeds, so thatthe material is guided into a compact stream 4 GB 2 123 374 A 4 and is directed positively towards the delivery target. The deflector may take manyforms, including smoothly curved, orfunnel shaped to guide into the stream also the crop from beneath.

Referring nowto Figure 6, the elevatorshown there differsfrom that shown in Figures 4 and 5 in thatthe feed-on section 16 is horizontal, both belts are driven, and atthe delivery end, the lower belt run is longer than the upper belt run. This fast aspect helps to reducethe amount of stray material emanating from the underside of the material stream. It also makes spring-loading of the upper end rollers 30 of the lower belt optional because nowthe belt 10 itself can flexto accommodatethe crop bulk as it passes underthe upper return roller24.

As an alternative, the upper belt run may extend beyond the lower atthe delivery end e.g. in the mannershown in Figure 1 forexample.

Turning nowto Figure7,this showsa sectioned side view of a single-box shroud 71 in which the two belt runs, preferably both driven, are accommodated. Spaced apart pairs of guiding rollers 73,74, springloaded towards the centre, apply intermittent pressure on to the load carrying belts 10, 12. 25 With this particular embodiment, although the construction of the belt housing has been simplified, very steep elevating angles upto the vertical can nevertheless be achieved because backsliding of the material being conveyed is prevented bythe idling 30 rollers 73,74. In fact the range of materials which can 9 5 be conveyed with this embodiment can be extended to include relatively free-flowing substances. In a variation (notshown) of the Figure 7 embodiment,the return runs of the conveying belts can be taken outside the central box-section to separate ducts, in the manner shown in Figure 5 for example. In this case, the radius arms of the squeezing rollers 73, 74 ca n be fitted i nsi de o r outsi de th e side p 1 ates of th e sh ro u d assem bly 62. 1 n th e 1 atte r case th e ro 1 ler spindles will pass through arcuate slots in the side walls, and the slots can be dimensioned so that they limit roller movement towards and away from the centreline.

It should be appreciated that the spring means urging the two opposed idling rollers 73,74 towards the conveying belts maybe selected to exert even or uneven pressure. If the latter case, the conveying belts can be caused to be displaced to one side or the other. Thus if, in successive pairs of rollers, the spring means on alternate sides of the duct are stronger, or 115 weaker, then the belts can be made to take a zig-zag path, so that in a vertically inclined elevating system the mass of the material being conveyed is alternately supported by sections of the right-hand and left- hand belts.

Figure 9 shows an alternative means of providing a zig-zag conveying path by having the co-operating regions 18,22 of sandwich conveying belts 10, 12 forced into a zig-zag shaped path by spaced single spring-loaded idling rollers 73,74 acting alternately from opposite sides. As indicated in broken line, on maximum deflection,the rollers are able to move through apertures in the flanged innerwalls of the elevatorshroud.

In a variation (not shown) of the Figure 8 embodi- 130 - -1 ES ment, the three-section shroud assembly shown in Figure 8 is replaced by a single-duct structure of appropriate width accommodating both the elevating and the return runs of the two-belts.

It should be pointed outthat in the two embodi ments shown in Figures 7 and 8 and theirvariations, the spring-loaded rollers 73,74 may be so dimen sioned or positioned thatthey are permanently, instead of occasionally, in contactwith the returning belt runs. These latterwould then operateto provide an additional forceto help rotatethe rollers.

In very long elevators employing zig-zag conveyin paths, it will be necess-oryto make allowances for!shortening and lengthening of the belt runs Under varying load conditions. This may be achieve-. f%r 3xarnnle, by a parallelogram-type suspensio-. of thc 3nd be" - -qupporting rollers so thattheycan readily movs _- appropriate distance in and againstthe directicrj of crop movement.

Referring now lastlyto Figure 10, this shows a plar --giew sf F. shrouded belt elevator8 which receives -hopped rnaterial from a crop-slicing rotor80 -ind,nonv-sy,! it side-waysfor delivery into a bulktrailer82 beinC driven alongside. By pivoting the elevator8 9 C; th ro 3 gh 90 deg rees a bo ut a ve rtica 1 spi n d I e ben eath th e feed-o n sectio n, th e elevator ca n be used a Iternatively to deliver material into a trailer or bulk container 84 drawn in-line,for example behind a harvester.

If used in th, stationary mode, the elevator of Figure 9 can be nimung th rough any angle up to at least 180 degrees.. for exam pie when filling material sores. The inclined part of any of the elevators described may be folded over by pivoting, for r1o exa mpl e at the spi ndle of the intake rol ler of the u ppebelt, or thy h ing iP2,, sections about a Iternative pivots.

P shcwuld hs.,:jr e. clea r that featu res presen! in any PjrtiCU lar em bc, f? -%-nt of this on ventior as above -vailablefor -nd large, alss F inclusion in qn--,; - -,er embordiment not a!read,,i possessing the F-_-ure concerned. Some, but by no means all, of thc- -- possibilities have already been outlined above in discussing the illustrated embodiments. Another example is, for instance, the replace- ment of rollers 15 in the embodiments of Figure 4 onwards bythe bogey arrangement44 shown in the Figure 2 arrangement. Another example would be the introduction of squeezing rollers 73,74 in the embodiments of Ficiures 1 and 2.

Dual purpose elevators according to the present invention are suitable for a wide range of materials, including cohesive materials. In operation, theytend to compactthe conveyed material and this can be advantageous in certain cases where low density compressible material is being elevated in orderto fill a container.

As already mentioned in the introductory portions of the application, the belts 10, 12 may, if desired, be provided with cleating spanning only part of the width of each belt in such away asto prevent interference between the cleats should there be any relative movement between the two belts. One such arrangement is depicted in the cross section of Figure 3 which shows two such belts co-operating atthe elevating section of the elevator. As will be seen from p GB 2 123 374 A 5 this Figure, in the illustrated embodiment, belt 12 is provided with cleats 58 spaced apart along a central region of the beltwhereas belt 10 is provided with cleats 60 lying on either side of cleats 58 and spaced therefrom. Other suitable arrangements are also possible, of course.

Besides the advantages already mentioned, the elevator of the present invention also enables complete longitudinal fill of the conveying space to be achieved with some materials, regardless of elevating angle, as opposed to the intermittent fill achievable with known designs of beft (or bucket) elevators which are dependent on elevating angle and the angle of repose of the material. Thus the present invention allows elevators to be constructed which will operate satisfactorily at virtually any desired angle of elevation.

In addition, the simplicity of design, togetherwith minimal friction and slip of material, favour a low power requirement and quiet operation, while as already suggested, variable trajectory, range and direction of delivery can also be incorporated. Moreover, unlike the flexible wall approach of existing dual purpose belt-type conveyors, where still more elaborate support means-are required for wider belts, the principles incorporated inthe twin-belt elevators of the present invention are suitable for any width of belt.

This invention finds particular application inthe

Claims (1)

1. transporting and loading of polmer materials, granular materials e.g.

   seeds or grain, aggregate nwaterials including gravel and coal, long and chopped fibrous materials and small unit loads. CLAIMS or more rollers:are-mounted on a frame whtdh comprises said pivotally- mounted support, which frame is pivotally mounted on a non-pivotting support.

   8. An elevator asclaimed in any preceding claThn when including the limitations of Claim 2 in which the spring-loading of the roller means is adjustable, a single adjustment changing the tension of both belts- 9. An elevator as claimed in any preceding claim in which the two belts are supported on as few rollers as convenient so as to encourage the belts to self-tension and self-adjust.

   10. An elevatoras claimed in any of Claims 1 to 8 in which the cooperating regions of the two belts are urged together by spring-loaded rollers orthe like.

   11. An elevator as claimed in Claim 10 in which the spring-loaded rollers orthe like constrain the co-operating regions of the two belts to follow a zig-zag path.

   12. An elevator as claimed in any preceding claim in which the loadretaining run of the second belt is guided about a top support roller of the first belt so as to encourage said cooperation between the second belt and the elevating-region of thefirst belt.

   13. An elevator as claimed in any preceding claim in which the inclination of the elevating and loadretaining regions of the belts is adjustableto allow elevating at a range of angles.

   14. An elevator as claimed in any preceding claim in which the second belt overhangs the upper end of the first belt so as to predetermine the trajectory of discharge of material from the elevator.

   15. An elevatoras claimed in any of Claims 1 to 13 in which at the delivery end of the elevator, the run of 1. Atwin-belt elevator comprising a load-suppor- 100 the first belt projects furtherthan the run of the ing first belt having an elevating region which second belt.

   co-operates with the elevating region of a load- 16. An elevator as claimed in any preceding claim retaining second belt to convey the load to a in which the first and/or second belts are each flat or discharge location positioned forwardly of the load- cleated as desired and preferably of the same or accepting region of the first belt, the operative run of 105 roughly the same width.

   the first belt being formed and divided into said 17. An elevatoras claimed in any of Claims 1 to 15 elevating region and said load-accepting region by a in which the first and second belts are cleated belts lower support roller means of the second belt. having the cleating spanning different transverse 2. An elevator as claimed in Claim 1 in which the regions of the two belts so that marginal speed roll er means is carried on a pivotal ly-mou nted 110 differences between the two belts will not cause support on which it is spring-loaded towards the interference between the cleats at the elevating region of the elevator nor prevent a degree of eroughing from being achieved.

   18. An elevator as claimed in any preceding claim including troughing means effective to impart a trough-like shape to the elevating regions of the elevator.

   19. An elevator as claimed in any preceding claim including spillage prevention means arranged to flank or surround the first and second belts atthe elevating region of the elevatorto discourage spillage ol conveyed material from this region.

   20. An elevatoras claimed in any of Claims 1 to 18 including spillage prevention means arranged to flank or surround the first and second belts atthe elevating region of the elevatorto discourage spillage of conveyed material at this region and also to support at least in partthe two belts atthis region in such away as to impart a trough-like shape to the elevating regions of the elevator.

   adjacent region of the first belt.

   3. An elevatoras claimed in Claim 1 orClaim 2 in which the second belt is kept taught around the roller means so that the entrance to the elevating section ol the elevator is accurately defined bythe position of the roller means.

   4. An elevator as claimed in any preceding claim in which the roller means comprises a relatively large diameterroller.

   5. Anelevatorasclaimed inanyof Claims 1 to3in which the roller means comprises two or more rollers arranged to shape the operative run of the first belt gradually in the region of directional change.

   6. An elevator as claimed in Claim 5 when 125 including the limitations of Claim 2 in which the two or more rollers are mounted on a frame which is itself pivotally attached to said pivotally-mounted support.

   7. An elevator as claimed in Claim 5 when including the limitations of Claim 2 in which thetwo 6 GB 2 123 374 A 6 21. An elevator as claimed in Claim 19 or Claim 20 in which the spillage prevention means is a tube or other hollow section surrounding or substantially surrounding thefirst and second belts atthe elevating 5 region.

   22. An elevator as claimed in Claim 21 in which the spillage-prevention means comprises a threesection device having a centre section surrounding or substantially surrounding the co-operating runs of the two belts atthe elevating region of the elevator and two outersections surrounding the return runs of the two belts atthat region.

   23. An elevator as claimed in anyone of Claims 1 to 18 including spillage prevention means in the form of a single-duct shroud in which all the belt runs are accommodated.

   24. An elevator as claimed in Claim 23 in which the shroud is foldable about a hinge lying parallel to the cross-sectional planes of the belts.

   25. An elevator as claimed in Claim 23 or Claim 24 in which the belts are supported on free-wheeling rollers each arranged to keep apartthe foward and return runs of an associated belt and to derive drive from contact with both said runs.

   26. An elevator as claimed in any preceding clairn in which the elevating region of the first belt leads to an extension region provided either by the first belt o by a third belt.

   27. An elevator as claimed in Claim 26 in which the inclination of the extension region is adjustable.

   28. An elevator substantially as hereinbefore described with reference to andlor as illustrated in Figure 1, Figure 2, Figure 3, Figures 4 and 5, Figure 6, Figure 7, Figure 8, or Figure 9 of the accompanying drawings.

   29. Atwin-belt elevator comprising a load-supporting first belt having an elevating region which co-operates with the elevating region of a loadretaining second beitto convey the load to a discharge location, the operative run of the first belt being formed and divided into said elevating region and said load-accepting region by a lower support roller means of the second belt and the co-operating regions of the two belts being urged together by spring-loaded rollers or the like to constrain the co-operating regions of the two belts to follow a zig-zag path.

   30. An elevator as claimed in Claim 29 and substantially as hereinbefore described with refer- enceto andloras illustrated in Figure 8of the accompanying drawings.

   31. An elevator as claimed in Claim 29 or Claim 30 when including the limitations introduced by any of Claims 2to 9 or by any of Claims 12 to 28.

   Printed for Her Majesty's Stationery Office byTheTweeddale Press Ltd., Berwick-upon-Tweed, 1984. Published atthe Patent Office, 25 Southampton Buildings, London WC2A lAYfrom which copies may be obtained.