WO2004089059A1

WO2004089059A1 - Methods and apparatus for topping vegetables prior to harvesting

Info

Publication number: WO2004089059A1
Application number: PCT/GB2004/001407
Authority: WO
Inventors: David Nicholson
Original assignee: Nicholson Machinery Ltd
Current assignee: Nicholson Machinery Ltd
Priority date: 2003-04-05
Filing date: 2004-03-30
Publication date: 2004-10-21
Anticipated expiration: 2005-10-05
Also published as: GB0307915D0

Abstract

A method for topping vegetables prior to harvesting comprises the steps of: righting the unwanted tops of the vegetables, cutting off the unwanted tops, uplifting the severed tops in an airstream and depositing the tops with the aid of a physical guide arrangement to provide a relatively gentle, slow and substantially controlled descent of the severed tops under the action of gravity. The apparatus preferably employs a pair of centrifugal fans to generate the airstream, the fans being connected at their air inlets by a hollow tube having an elongate opening to allow tops to be sucked in. Connected to the exhaust ends of the fans are advantageously connected respective cylinders having respective internal helical guides which provide a controlled rate of descent of the tops.

Description

METHODS AND APPARATUS FOR TOPPING VEGETABLES PRIOR TO

HARVESTING

Field of he Invention

The invention relates to methods and apparatus for topping vegetables prior to harvesting, as well as a method for righting and a method for depositing the unwanted tops of vegetables and an apparatus for uplifting the unwanted tops of vegetables.

Background of he Invention

There is a need for vegetables to be presented to the end-user, e.g. a customer in a supermarket, in as good a condition as possible, since it is acknowledged that most customers are put off by produce which looks in any way "below par", even though such produce may still be nutritionally acceptable, h the case of onions and other root vegetables, it can be off-putting if the upper foliage (so-called "tops") or parts of the root are still left on the produce. In order to remedy the problem of the tops, it is known to remove the tops (a process called "topping") either before or after harvesting. Topping prior to harvesting is preferred, since this is more easily automated, the produce being already embedded in the ground. Furthermore, produce without tops takes up less space and therefore greater numbers can be packed into a given volume for transportation from the field compared with untopped produce, which reduces transport costs. The topping of produce such as onions can be achieved either manually or, as already mentioned, by machine. In either process there are attendant problems. In the first place, if topping is done without sufficient care both the onion and its top can become at least partially mulched, i.e. becomes very wet and pulpy, and contact between such mulched parts and surrounding onions can cause a stain to be applied to the latter. This stain may start out on the outer skin only, but can over time seep down into deeper layers ofthe onion, thereby spoiling the produce. A problem at least as serious is that of fungal contamination of the produce. This may take the form of botrytis, which is carried in the air as spores and shows as a powdery bloom on affected produce. It is possible to remove the outer skins of onions which are suffering from botrytis, but again that spoils the appearance of the vegetable. Since botrytis spreads very readily, it is desirable in any topping process to keep any contact between the fungal spores and the produce to be harvested down to a minimum.

In the case of manual topping, the process of cutting off the tops is often not very efficient, with consequent problems of mulching of the produce. Also, the scissors or other implement used for topping have to be periodically washed in order to remove traces ofthe fungal spores which may have accumulated on the blades. This, of course, is time consuming and reduces topping efficiency. Topping by hand is usually slow anyway, so there is an incentive to automate the process. However, even when topping is carried out automatically using known machines, it is common to find that an onion or other produce will have been cut several times, the result being, as with manual topping, increased wetness ofthe produce. In addition the cuts made may not always be very accurate, so that it is not uncommon for pieces of topping material (e.g. parts of leaves) to still remain on the produce after harvesting.

The present invention seeks to mitigate the above drawbacks of the known topping techniques.

Summary ofthe Invention

In accordance with a first aspect of the invention there is provided a method for topping vegetables prior to harvesting comprises the steps of: righting the unwanted tops of the vegetables, cutting off the unwanted tops, uplifting the severed tops in an airstream and depositing the tops with the aid of a physical guide arrangement to provide a relatively gentle, slow and substantially controlled descent of the severed tops under the action of gravity.

An apparatus adapted to carry out the method just described, comprising one or more centrifugal fans, which -or each of which- entrains and lifts the severed tops either directly or by means of a transverse hollow tube, the tube having a transverse opening allowing the ingress of air in which the severed tops are entrained and uplifted. The fans may share a common drive shaft co-axial with the tube. The inventors have found that this fan configuration produces a helical movement of the tops once inside the transverse hollow tube, this helical movement then interfacing with the fan blade rotation such as to facilitate entry of the tops into the fan-blade system. The tops are partially cut up in the centrifugal fan which generates moisture causing any spores present on the tops to adhere to the tops such that they are not subsequently released with the exhausted air which might result in them settling on the produce to be harvested.

In order to provide an initial righting of the tops prior to cutting, a multiple- vaned paddle is provided, which rotates in use and physically lifts especially the higher leaves, etc, atop the produce which is to be harvested and thereby righting the unwanted tops of the vegetables. Assisting this operation is a sawtoothed configuration of the edges of the paddle vanes. This provides a "combing" action ofthe tops, which reduces the risk of damage to the latter. A second action performed by the paddle is to restrict the ingress of air underneath the apparatus to a low region near the ground. This assists the suction action ofthe fan system.

It is advantageous if a series of rotary cutters are used for cutting off the unwanted tops, wherein each ofthe rotary cutters has a cutting path which overlaps that of its neighbouring cutter. The use of a series of rotary cutters, as opposed to, for example, a bandsaw, ensures a more accurate cut, since the cutters can more easily be supported across the width of the mobile chassis supporting the various components ofthe apparatus.

In order to dispose of the tops, once cut, a cylinder arrangement may be provided having top and bottom open areas, an inlet area communicating with the exhaust ends of the centrifugal fans and, disposed inside the cylinder arrangement, a helical guide arrangement, wherein, in use, the tops contained in the exhaust of the centrifugal fans are directed downwards at a controlled rate by the helical guide arrangement and out through the bottom open area of the cylinder arrangement. This controlled exiting of the tops reduces the risk of the mulched tops coming into contact with the produce on the ground which, could produce spoiling of that produce.

A further benefit is to be gained if the air in the fan exhaust is allowed to escape through the top open area of the cylinder arrangement. This reduces the velocity at which the partially mulched tops (and attached spores) exit the apparatus and thereby helps to keep such spores away from the produce on the ground.

In a preferred realisation of the apparatus according to the invention, the cylinder arrangement comprises a pair of cylinders having respective top and bottom open ends, respective inlets attached to the exhaust ends of respective centrifugal fans and respective internal helical guides. By this means the exhaust from each fan can be made to interface with its own helical guide, which provides for a more certain guiding action on the exiting tops.

It is expedient if a section of helical guide exists above the point of interface between the fan exhaust and its associated cylinder. This measure enables tops, which happen to be thrown upwards on entering the cylinder, to be caught by the helix and brought back down again in a controlled manner.

In order to dispose ofthe tops in an even more controlled manner, the bottom open ends of the cylinders are preferably the open ends of respective deflection members which are continuations of the bottom ends of the respective cylinders, the deflection members serving, in use, to direct the tops contained in the exhaust laterally outwards, so that at least some of the tops are deposited in wheelings associated with the apparatus. Thus tops deposited in the wheelings will by and large be isolated from the produce to be harvested. Preferably one or more cyclones are used to separate the tops from the air exhausted from the centrifugal fans. The use of such cyclones assists in reducing the velocity with which the tops exit the device.

A third aspect of the invention provides for a method for depositing the unwanted tops of vegetables subsequent to a topping process in a topping machine, the method comprising the steps of: directing an airstream, in which the severed tops are entrained, into a chamber having first and second open ends; allowing the air in the airstream to escape by way of the first open end and, with the aid of a physical guide arrangement, providing a relatively gentle, slow and substantially controlled descent of the tops under the action of gravity, the tops being thereby deposited by way ofthe second open end.

In a fourth aspect of the present invention, a method for topping vegetables prior to harvesting is provided, comprising the steps of: cutting off the unwanted tops of the vegetables using a wheeled mobile apparatus; conveying the severed tops in an airstream to a chamber, and conveying the tops from the chamber down into a wheeling created by the wheels of the mobile apparatus or, which is preferred, the wheels of the towing vehicle, since then the wheeling is likely to be more substantial.

A fifth aspect of the invention comprises an apparatus for topping vegetables prior to harvesting, comprising: a righting section for righting the unwanted tops of the vegetables prior to cutting, a cutting section for cutting off the righted tops and a lifting section for lifting the severed tops, wherein the righting section and the lifting section are configured to create an air-pressure drop in a zone between the righting section and the cutting section.

The righting section preferably comprises a device for generating an air draught close to the ground and the lifting section comprises a suction generator. The generation of a low air draught reinforces the suction from the suction generator and ensures that sufficient suction exists very near ground level for the tops, once cut, to be entrained in the airstream generated by the suction generator. Included within the scope of the invention is apparatus for topping vegetables prior to harvesting, substantially as described herein with reference to and as illustrated by any appropriate combination ofthe accompanying drawings.

Included within the scope of the invention is a method of topping vegetables prior to harvesting, substantially as hereinbefore described.

Brief Description ofthe Drawings

An embodiment of a topping apparatus will now be described, by way of non-limiting example only, with the aid ofthe drawings, of which:

Figure 1 is a side view of a topping apparatus according to the invention;

Figure 2 is a top view of the apparatus of Figure 1 ;

Figure 3 is a top view of a preferred cutting arrangement for use in a topping apparatus according to the invention;

Figure 4 is a partial view in the direction "TV -TV" shown in Figure 2, and

Figure 5 is a partial view corresponding to that of Figure 4 and comprising an adjustable ejection arrangement.

Figure 6 is a perspective representation of a topping apparatus which utilises cyclones as a means to separate the cut tops from the exhausted air.

Detailed Description of an Embodiment ofthe Invention

Referring to Figures 1 and 2, an apparatus for topping vegetables prior to harvesting comprises a chassis 10 having a pair of rear wheels 12 to allow towing ofthe chassis by a farm vehicle such as a tractor (not shown). Mounted on the chassis 10 is a centrifugal fan arrangement comprising a pair of centrifugal fans 14 whose outlets face backwards in terms of the direction of travel of the chassis. The fans contain, in a preferred form of the invention, a set of rotatable blades 26 which are curved in a forward direction relative to the direction of rotation of the blades. This is advantageous for reasons described later. Connecting the inlets ofthe fans is a horizontal tube 16, which is hollow and comprises an elongate opening 18 on its underside. A drive shaft 19 connects the blade assemblies ofthe respective fans, the shaft being driven at one end by a chain drive housed in a housing 21 and linking with a second drive shaft 23, which in turn is powered through a gearing arrangement 25 and a coupling 56. The outlets 20 ofthe two fans 14 lead in sealed manner into respective cylinders 22 mounted on the chassis just behind the fans. Each cylinder has secured on its inside wall a helical guide 24. This consisted in the prototype of the present apparatus of four 10mm diameter rods welded to each other side-by-side, the outermost rod being welded to the inside wall of the respective cylinder. The main reason for employing 10mm rod was that, while it was inherently strong, it was also relative easy to conform it to the shape of a helix around the inner wall of the cylinder, welding it to the wall along the way. Once the outermost rod is in place, a second rod is then laid against that and welded, a third welded to the second, and so on for as many rods as are needed to provide an adequate guide width. In the present case, in which the invention is used mainly for topping onions, a guide width of around 40mm is found to be suitable, which requires the use of four such rods. The pitch of the helix is preferably approximately 200mm. Where other types of produce are to be topped, the helix width and possibly also the pitch may need to be modified.

Underneath the fan assembly is a cutter arrangement 28, which consists of a series of rotary cutters 30 (see Figure 3) disposed side by side along the width of the chassis. Each cutter 30 comprises a blade holder 32, which is attached at its central point to a drive spindle 34, which in turn is coupled to a drive mechanism for turning the blade holders. Pivoted at the ends of each blade holder is a blade 36. In operation the blade holders are rotated at high speed, so that the blades 36 are forced outwards by centrifugal force into the position shown. Pivoting of the blades, however, allows the blades to yield in the event that an obstruction, e.g. a stone, is encountered as the chassis is driven forwards. In the preferred embodiment being described, the path of rotation 38 of the blades of the various cutters overlap, so that there are no gaps in the cutting action on the produce covered by the apparatus. Located just in front ofthe fan arrangement is a rotatable paddle 40 comprising a cruciform arrangement of vanes 42. Each vane is provided with a sawtooth edge 44. The height of the vanes above the ground is adjustable, as shown by the arrow 46. Situated between the paddle 40 and the cutter 28 is a pair of baffles 48 and 50, which run virtually the whole width of the chassis and are fixed at their upper edges to the tube 16. In addition, the bottom edge of the baffle 50 is secured to a further, arcuate baffle 52 which approximately follows the curve of rotation of the sawtooth vane edges 44, but is spaced a small distance therefrom. The bottom edge of the baffle 48 reaches down approximately to the centreline 39 ofthe cutters 28 where the spindles 34 meet the blade holders 32 (see Figure 3). In order that the baffle 48 may not interfere with the spindles and other drive components of the cutters, it is given a slight forward curvature as shown.

The cylinders 22 are disposed vertically and are open at their top and bottom ends. However, the bottom ends communicate with respective deflecting members 60, which deflect the tops exiting the cylinders obliquely down and out through a further extension member 62, which releases the tops directly downwards into the so-called "wheeling" 64 made by the wheels 12 (see arrows 66 in Figure 4, which is a view in the direction "TV -TV" in Figure 2 through a cylinder 22, a deflecting member 60 and an extension member 62). This measure effectively keeps the unwanted tops away from the main crop to be harvested and ensures that any residual mulch or even fungal spores which may be present on the tops minimally affects the crop.

The chassis 10 is provided at its front end with one or more towing connections 54, which enable the chassis to be towed by a suitable vehicle, e.g. a tractor. In addition there is the already mentioned drive coupling 56 also at the front end, through which power is supplied by the towing vehicle to rotate one or more of the fans, cutter blades and paddle. The speeds of rotation of these items are completely independent of each other, though they may all be ultimately be driven via some gearing arrangement from the same source (e.g. the coupling 56). Alternatively, one or more of these rotatable items may be driven by other means, e.g. by electric power supplied by the towing vehicle or by a power source onboard the chassis. The operation of the topping apparatus in connection with the topping of onions will now be explained.

The chassis is towed over the crop to be harvested with all three rotatable elements, the fans, the cutters and the paddle vanes, rotating at a suitable speed in each case. These speeds will be such as to produce the effects now to be described and, with that in mind, can readily be ascertained by experiment accordingly. As shown in Figure 1, both fan blades rotate in the same direction (i.e. clockwise) from a view looking down onto the page and the paddle rotates anticlockwise. The cutters rotate in either direction depending on the orientation ofthe cutting edge of he blades.

As the chassis proceeds, the paddle vanes 42 perform a dual action: firstly, they physically push high weeds and leaves on the tops ofthe onions backwards ready for the action ofthe centrifugal fans. Secondly, they ensure that the suction airflow from the fans starts as near the ground as possible, i order to achieve this, it is preferred that there be a vane 42 fairly near the ground at all times. This effectively rules out the use of a two-vaned paddle, since both vanes will be approximately horizontal much ofthe time, but a paddle with four vanes or more will be effective. More than four vanes (e.g. five or six) is preferable in terms of performance, but of course such a paddle will be more expensive to manufacture and therefore four is a good compromise.

Once the paddle has physically prepared the foliage, so that the latter approaches an upright position, the foliage is made completely upright by the airstream generated by the centrifugal fans 14. This airstream extends across virtually the whole of the width of the chassis and is confined to a throat 70 formed by the area between the baffles 48, 50. The presence of the further baffle 52 assists in this confinement also. Due to the sweeping action ofthe paddle vanes air is swept backwards underneath the paddle and an area of low air pressure is created between the paddle and the cutters by virtue of the sucking action of the fans. This means that, as the chassis proceeds further, the foliage, etc, remains upright ready for the cutting action of the cutter blades, which are now unencumbered by the foliage. The suction created by the fans is distributed approximately evenly across the width of the chassis, this being assisted again by the presence ofthe baffles.

Once a cutter blade has cut off the top of an onion with its foliage, that top is instantly entrained upwards in the airstream, where it enters the opening 18 (transverse opening) made in the tube 16 and follows an approximately helical path along the transverse hollow tube, to one of the fan inlets, at which point it slots into the gap between the nearest pair of fan blades 26, where it is carried round by the rotation of these blades to then exit at the outlet end 20 of he fan. It is believed that the rotating component ofthe helical movement of he top along the tube is in the same direction as the rotating movement ofthe fan blades, which helps the top to engage with the fan blades with little consequent damage to, and therefore risk of undue cutting up (or mulching) of, the top. It is further believed that the helical flow of the air in the tube is assisted by the laminar air flow over the central drive shaft 19. The tops are partially cut up by the fan blades (26) such that some moisture is generated causing any spores present to adhere to the tops and not be subsequently vented with the exhausted air. Tops entering the tube near one end thereof will tend to be drawn towards the fan at that end, and vice versa. Tops entering the tube in the middle can go either way. At this point the top is projected by the exhausting airstream into the cylinder 22 associated with the fan in question, where it strikes the helical guide 24 at the nearest point and is compelled to follow the guide round and down till it finally exits the cylinder at its lower end, being then deflected outwardly and down into a wheeling 64 made by the towing vehicle. (This wheeling may or may not coincide with that of the chassis itself). The exhausting air travels upwards to escape at the open upper end ofthe cylinder.

It is preferable if the outlets of the fans lead into the outermost part of their respective cylinders occupied by the helical guide. By this means the tops are led directly onto the helix itself with consequently little risk of their simply dropping straight down through the central part ofthe cylinder.

It has been found by the present inventor that it is advantageous if tire centrifugal fan blades are curved outwardly in the direction of blade rotation, as shown in Figure 1, since this appears to result in less damage to the incoming tops than when a straight blade is used. The cutter arrangement shown in Figure 3 is only one possible arrangement which may be employed. Other arrangements are possible, including the use of a bandsaw. However, it has proved advantageous to use the illustrated system, since this interferes less with the desired airflow, but also because a bandsaw sfretcbing across the width of the chassis will tend to sag in the middle, which may then give rise to inaccurate topping ofthe onions. The multi-cutter arrangement shown in Figure 3, on the other hand, can be made not to sag by the provision of a rigid horizontal bar 53 on which the cutter holders 32 and spindles 34 are supported.

The sawtooth pattern on the edges of the paddle vanes fulfils a useful purpose, namely to tend to "comb" the tops into an upright position without unduly damaging them.

It will be noticed from Figure 1 that the helical guide 24 extends not only between the entry point ofthe fan exhaust and the bottom ofthe cylinder 22, but also between the entry point and the cylinder top. This is in order to prevent tops in the exhaust from travelling upwards and out of the top of the cylinder, from where they can land anywhere in an uncontrolled manner. Those tops leaving the fan outlet that do happen to fly upwards will be caught by the nearest part of the upper helix section and be guided down again along the rest of the descending helix.

In order to control the rate at which the tops enter the helix and begin their descent along it, it is expedient to provide some kind of choke at the upper opening ofthe cylinder 22. This, in the Figure 2 embodiment, takes the form of a butterfly flap 27 pivoted centrally to the wall of the respective cylinder at a point 29 and controlled by a suitable lever arrangement (not shown).

When the flap is fully closed the exhausting area for the air leaving the fans is a minimum and the rate of ejection ofthe tops from the fans is reduced so that the kinetic energy ofthe tops is relatively low as they strike the helix, resulting in a gentler descent ofthe tops along the helix. By contrast, a fully open flap increases the available area for the exhausting air and the result is a faster descent ofthe tops along the helix. It is also anticipated by the invention that some form of adjustment may be needed to the ejection-chute arrangement 60, 62 in order to cater for the possibly different wheeling spacings ofthe towing vehicle. This may be achieved by making the extension member 62 adjustable in some way. Figure 5 shows one possible method, in which the member 62 is made laterally wider so that it protrudes further out from the chassis 10 and is provided with a baffle 63 which can be slid along a groove 67 made in the deflecting member 60 and secured in any desired position by a locking nut 65. In this way the tops can be forced to exit laterally further out from the chassis.

Reference is now made to figure 6 of the diagrams which shows an alternative embodiment of the device which incorporates two cyclones 80 which are mounted at the outlets 20 ofthe two fans 14 as a means of separating the air from the outlets from the cut tops. The vegetable tops exit the outlets 20 at high speed due to the speed of the air emitted from the outlets 20. This can result in some of the vegetable tops exiting the ejection chute 60, 62 with considerable velocity which can result in the tops bouncing off the ground and coming to rest in unwanted positions such as amongst the main crop. This is a particular problem when the apparatus is operated at higher speeds. The use of the cyclones 80 in place of the cylinders 22 assists in overcoming this problem and additionally has the benefit that a larger number of cut tops can be separated from air with a higher velocity on exit from the outlets 20. The vegetable tops exit the outlets 20 into the cyclones 80 and then circulate around the cyclones 80 with a downwards helical motion. The circulation ofthe tops around the cyclones 80 reduces the kinetic energy of the tops and thus overall assists in reducing the velocity with which the tops subsequently exit the device. The air is vented from the cyclones 80 via the open area 81 in the upper faces ofthe cyclones. The tops exit via the base 82 ofthe cyclones and then pass into a chamber 84 that acts as a diffuser, the chamber narrows (not shown) to form a chute 83 from which the tops exit the device under gravity into the wheelings. The cyclones additionally incorporate a deflector (indicated by the dotted line 84) which assists in directing the tops away from the outlet 20 and so prevents the tops from re-circulating in the fast moving air from the outlet 20. The use of a cyclonic separation system of this type has an advantage over the previously described separation system in that it can separate a larger number of cut tops from a much higher flow of air. This in turn means that the topping device can operate at higher speeds and thus top a larger area of a crop in a reduced period of time. Additionally when using the cyclones described above it is not necessary to use the helical guide arrangement or deflection means to exhaust the tops laterally. The tops can be exhausted directly from the chute 83 into the wheelings without the use of the ejection chute 60, 62, thus further reducing the possibility of fungal contamination ofthe vegetable being topped.

It has been found that the size of the lip 85 relative to the diameter of the cyclone being used is important and the skilled man would be able to determine the appropriate ratio for the type of crop with which the cyclone is to be used.

It will be appreciated by those skilled in the art that various modifications may be made to the invention described herein without departing from the scope thereof.

For instance the air flow from the outlets 20 of the two centrifugal fans 14 used in the embodiment described could be comiected to a single larger cyclone, rather than using two separate cyclones, thus reducing the cost of producing the apparatus.

The pivoting blades of the rotating cutters can be replaced with blades which are not pivotally attached to the blade holders. Instead the blades are rigidly attached to the holders and a mechanism (of known type) is provided such that the blades and holder can lift in an upwards direction if the blade strikes a rigid object.

In this case the direction of rotation of the blades at the outermost edges ofthe device is in the direction of travel of the device in normal use, thus increasing the airspeed across the blade at this point. This in conjunction with the uplifting air generates a vortex which helps to untangle the tops and thus helps to ensure the tops enter into the transverse hollow tube via the opening 18 more cleanly than they would otherwise. This helps to prevent the cut tops becoming entangled around the central tube 16b (see figure 1), this arrangement can be incorporated into the preferred embodiment previously described.

It is believed that an alternative arrangement of the transverse hollow tube wherein the transverse hollow tube 16a has an annular cross-section formed between the outer 16 and inner 16b tubular member which surrounds the drive shaft, gives rise to an improved helical flow of air along the length of the annular space from the transverse opening towards the centrifugal fans due to an improved laminar flow of air over the inner tube 16b. The helical flow of air helps to prevent the tops from becoming wrapped around the inner tubular member 16b (or the central drive shaft ofthe previously described embodiment).

Claims

1. Method for topping vegetables prior to harvesting, comprising the steps of:

(a) righting the unwanted tops ofthe vegetables;

(b) cutting off the unwanted tops;

(c) uplifting the severed tops in an airstream;

(d) depositing the tops with the aid of a physical guide arrangement to provide a relatively gentle, slow and substantially controlled descent of the severed tops under the action of gravity.

2. Apparatus adapted to carry out the method as claimed in Claim 1, comprising one or more centrifugal fans, which -or each of which- entrains and lifts the severed tops either directly or by means of a transverse hollow tube, the tube having a transverse opening allowing the ingress of air in which the severed tops are entrained and uplifted.

3. Apparatus as claimed in Claim 2, comprising a multiple-vaned paddle which rotates in use and physically lifts especially the higher leaves.

4. Apparatus as claimed in Claim 3, wherein the vanes of the paddle have a sawtoothed edge.

5. Apparatus as claimed in any one of Claims 2 to 4, comprising a series of rotary cutters for cutting off the unwanted tops, wherein each ofthe rotary cutters has a cutting path which overlaps that of its neighbouring cutter.

6. Apparatus as claimed in any one of Claims 2 to 6, comprising a cylinder arrangement having top and bottom open areas, an inlet area communicating with the exhaust ends of the centrifugal fans and, disposed inside the cylinder arrangement, a helical guide arrangement, wherein, in use, the tops contained in the exhaust ofthe centrifugal fans are directed downwards at a controlled rate by the helical guide arrangement and out through the bottom open area of the cylinder arrangement.

7. Apparatus as claimed in Claim 6, wherein the air in the exhaust is allowed to escape through the top open area ofthe cylinder arrangement.

8. Apparatus as claimed in Claim 6 or Claim 7, wherein the cylinder arrangement comprises a pair of cylinders having respective top and bottom open ends, respective inlets attached to the exhaust ends of respective centrifugal fans and respective internal helical guides.

9. Apparatus as claimed in Claim 8, comprising a section of helical guide above the point of interface between each fan exhaust and its associated cylinder.

10. Apparatus as claimed in Claim 8 or Claim 9, wherein the bottom open ends of the cylinders are the open ends of respective deflection members which are continuations of the bottom ends of the respective cylinders, the deflection members serving, in use, to direct the tops contained in the exhaust laterally outwards, so that at least some of the tops are deposited in wheelings associated with the apparatus.

11. A device as claimed in claims 1 to 5 wherein one or more cyclones are used to separate the tops from the air exhausted from the centrifugal fans.

12. Method for depositing the unwanted tops of vegetables subsequent to a topping process using a topping machine, comprising the steps of: a. directing an airstream, in which the severed tops are entrained, into a chamber having first and second open ends; b. allowing the air in the airstream to escape by way ofthe first open end, and c. with the aid of a physical guide arrangement, providing a relatively gentle, slow and substantially controlled descent of the tops under the action of gravity, the tops being thereby deposited by way ofthe second open end.

13. Method for topping vegetables prior to harvesting, comprising the steps of: a. cutting off unwanted tops of the vegetables using a wheeled mobile apparatus; b. conveying the severed tops in an airstream to a chamber; and c. conveying the tops from the chamber down into a wheeling created by the wheels ofthe mobile apparatus.

14. Apparatus for topping vegetables prior to harvesting, comprising: a righting section for righting the unwanted tops ofthe vegetables prior to cutting, a cutting section for cutting off the righted tops and a lifting section for lifting the severed tops, wherein the righting section and the lifting section are configured to create an air-pressure drop in a zone between the righting section and the cutting section.

15. Apparatus as claimed in Claim 14, wherein the righting section comprises a device for generating an air draught close to the ground and the lifting section comprises a suction generator.

16. Apparatus for topping vegetables prior to harvesting, substantially as described herein with reference to, and as illustrated by any appropriate combination of the accompanying drawings.

17. Method of topping vegetables prior to harvesting, substantially as hereinbefore described.