WO2010062199A2

WO2010062199A2 - Mowers

Info

Publication number: WO2010062199A2
Application number: PCT/NZ2009/000260
Authority: WO
Inventors: Barry Herbert Funnell
Original assignee: Aire Cut Company Limited
Priority date: 2008-11-26
Filing date: 2009-11-26
Publication date: 2010-06-03
Also published as: WO2010062199A3

Abstract

Mowers producing an air flow that inhibits the build up of cut material on the mower housing and that facilitates fine comminution of cut material. The blades produce lift so that grass may be lifted towards the cutting blades for effective cutting whilst an "air curtain" inhibits the build up of cut material on the housing. Cut material within the housing may be directed towards a region in which cutting blades pass an anvil to facilitate fine comminution, reduce dwell time of the cut material in the mower and reduce the build up of cut material on walls of the housing. Consequently the mowers may be of reduced size, have improved maneuverability and energy requirements may be greatly reduced. Furthermore the mowers may produce finely comminuted organic material that is easily dispersed and utilized.

Description

MOWERS

FIELD OF THE INVENTION

This invention relates to mowers and arrays of mowers. More particularly, although not exclusively, the invention relates to reducing clogging from cut grass by improving airflow through the mower and providing fine comminution of cut material.

BACKGROUND OF THE INVENTION

A variety of mowers are employed to cut lawn and the like including hover mowers, mulching mowers, catcher mowers, side throw mowers and trimmers.

Hover mowers, such as the FLYMO™ mower, draw air in through an air intake at the top and force it down via a fan so that this enables the mower to ride on a cushion of air. This airflow forces grass down. As the FLYMO™ has a flat blade, it does not draw air from the ground upwards. Therefore the grass does not stand up and so does not cut the grass as well as if the grass were drawn up. Because there are no anvils such mowers also do not comminute the grass into small pieces to facilitate uptake of nutrients in the soil.

Mulching mowers on the other hand do comminute the grass but not into finely comminuted portions providing readily accessible nutrients to the lawn. Further, such mowers do not include a fan and the air flow within the mower housing tends to cause a build up of cut grass around the top of the mower. This restriction considerably increases the size of motor required. Such mowers may also require wheels, rather than being supported on a cushion of air, and so can damage the lawn and require vehicles having significant power to tow them.

Catcher mowers produce an air flow to convey cut material to a catcher, either with or without an air fan. However, they do not produce an "air curtain" to inhibit build up of cut material on the housing.

Side throw mowers cut grass and eject it to the side. This consumes much energy and does not finely comminute the cut material or prevent build up of cut material within the housing.

There are also trimmers which allow pivoting of the trimmer head with respect to the drive shaft by means of a flexible coupling. . The pivotal coupling has resistance to pivoting so that the front of the trimmer is oriented downwardly during forward motion and the rear of the trimmer is oriented downwardly during backwards motion. Such trimmers have a flexible pivotal coupling that allows lateral pivoting which does not allow positive control of the trimmer head and can be hazardous for operators of the trimmer.

It is an object of the invention to provide an improved mower or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

Mowers according to various aspects of the invention produce an air flow that inhibits the build up of cut material on the mower housing and facilitates fine comminution of cut material. Grass may be lifted towards cutting blades for effective cutting whilst an "air curtain" may inhibit the build up of cut material on the housing. Cut material within the housing may be directed towards a region in which cutting blades pass an anvil to facilitate fine comminution. ^"What is not reduced then exits through the partial anvil. This avoids the build up of cut material in the housing. Consequently energy requirements may be greatly reduced.

According to one exemplary embodiment there is provided a lawn mower including: a. a housing having an open underside face and an air intake;

b. a cutting head rotatably mounted within the housing including a plurality of blades wherein the blades are arranged to draw air and material to be cut from below the underside face of the housing into the housing;

c. a fan arranged to draw air into the housing through the air intake, the arrangement being such that air and cut material drawn into the housing through the cutting head is transported upwardly within the housing and air drawn into the housing through the air intake transports the cut material downwardly and outwardly to the periphery of the cutting head.

According to another exemplary embodiment there is provided a hover mower including:

a. a housing having an open underside face and an air intake;

b. a fan arranged to draw air into the housing through the air intake; c. a cutting head rotatably mounted within the housing including a plurality of blades; and

d. an anvil extending at least partially around the periphery of the open face of the housing spaced apart from the blades so as to facilitate comminution of cut material.

According to a further exemplary embodiment there is provided a hover mower including:

a. a housing having an open underside face and an air intake;

b. a fan arranged to draw air into the housing through the air intake;

c. a cutting head rotatably mounted within the housing including a plurality of blades; and

d. a drive shaft coupled to the cutting head by a freely pivoting coupling allowing substantially free pivoting forward and aft.

According to a further aspect there is provided a mower including:

a. a tubular housing having an air intake at one open end and an open underside face at the other end;

b. a fan arranged to draw air into the housing through the air intake;

c. a cutting head rotatably mounted within the housing including a plurality of blades; and d. an anvil extending at least partially around the periphery of the open face of the housing spaced apart from the blades so as to facilitate comminution of cut material.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention.

Figure 1 shows a side view of a hover mower;

Figure 2 shows a cross sectional view through the housing of the mower shown in Figure 1;

Figure 3 shows an underside view of the mower shown in Figure 1 ;

Figure 4 shows a mower with support wheels;

Figure 5 shows an underside view of the mower shown in Figure 4;

Figure 6 shows an underside view of a mower having three cutting heads;

Figure 7 shows an array of mowers;

Figure 8 shows a trimmer having a pivotable housing;

Figure 9 shows a perspective view of a hover mower;

Figure 10 shows an underside view of the hover mower shown in figure 9;

Figure 11 shows a cross sectional view of the hover mower shown in figures 9 and 10;

Figure 12 shows a perspective view of the fan used in the hover mower shown in figures 9 to 11; Figure 13 shows a strimmer; Figure 14 shows a cross sectional view of the strimmer shown in figure

13;

Figure 15 shows a dual cutting head mower;

Figure 16 shows an underside view of the mower shown in figure 15. Figure 17 shows a cross sectional view of the mower shown in figures 15 and 16; Figure 18 shows a mower with three tubular housings containing cutting heads;

Figure 19 shows an underside view of the mower shown in figure 18; Figure 20 shows a cross sectional view of the mower shown in figures 18 and 19.

Figure 21 shows an integrally formed anvil ring; Figure 22 shows a dual fan arrangement; and;

Figure 23 shows a side view of the dual fan arrangement shown in figure 22;

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Definitions

In this specification the following words shall have the meanings defined below:

"Mower" includes cutting mowers, mulching mowers, hover mowers, catcher mowers, side throw mowers, trimmers, and the like.

"Anvil" means a surface positioned near a blade that in combination with a blade facilitates comminution of cut material.

"Comminute" means to divide cut material into small portions. "Micronized" means to divide cut material into portions of micron size (typically tens or the low hundreds of microns).

"Blades" includes any cutting element including blades and flails.

"Air curtain" means an airstream bounding and repelling an adjacent airstream.

Referring to Figure 1 there is shown a hover mower having a housing 1 , motor 2 and handle 3. A series of openings 4 provide an air intake from the outside of housing 1 into the interior of housing 1. As shown in Figure 2 motor 2 rotates cutting head 5 and fan 6 within housing 1 . Cutting head 5 includes a support disc or bar 7 having a plurality of blades 8 extending outwardly therefrom. Whilst the number of blades may vary depending upon the blade design and application three blades are shown in this embodiment. In this embodiment the blades are preferably detachable blades of the type described in PCT application No. PCT/NZ2OO7/OOO139, the disclosure of which is hereby incorporated by reference. Blades 8 are shaped and orientated to generate lift so that material to be cut is drawn upwardly towards blades 8 and cut effectively.

In this embodiment fan 6 is a backward drag centrifugal fan that produces an airflow that is directed downward, outwardly and rotationally in the direction of rotation (clockwise in this case) of the cutting head 5. The fin height of the fan is preferably between 8 to 20 percent of the diameter of the cutting head. The area of openings 4 forming the fan intake is preferably between 15 to 30 percent of the diameter of the cutting head. Additional blades may be added to the periphery of the fan which will act as additional foils to create a greater down draft. In this embodiment a pair of anvils 9 and 10 is provided about the periphery of cutting head 5 (i.e. the circle described by the cutting head when rotating). As shown in Figure 3 arrow F indicates the front of the mower when viewed from the underside. In this embodiment anvil 9 extends between 60° to 150° from the front of the mower and anvil 10 extends between 240° to

330° from the front of the mower. Each anvil extends around about a quarter of the periphery of the cutting head. By having the anvils extending only partially around the housing consistent air pressure may be maintained throughout the^"housing to assist hovering (i.e. the vacuum and negative air pressure created by the angle of the cutting blades can be compensated).

The spacing between each blade 8 and respective anvils 9 and 10 is preferably between 1 mm to 6 mm and most preferably about 3 mm. This facilitates fine comminution of cut material as will become apparent from the description of the operation of the mower.

Air is drawn from outside the housing into the housing through openings 4 as indicated by arrows A. Fan 6 directs this air downwards, outwardly and rotationally in the direction of rotation of the fan as indicated by arrows B. Blades 8 generate lift and so lift up material to be cut and direct the air (drawn from the ground) and cut material upwardly into the housing as indicated by arrows C. Airflows B and C then combine to form airflow D which directs air and cut material downwardly and outwardly towards the periphery of housing 1 by centrifugal forces. When moving in the forward direction cut material is drawn towards the top of the housing and is met with airflow B being forced from the fan 6 downwardly, outwardly and rotationally in the direction of rotation R shown in Figure 3 so that cut material is directed towards the region of anvil 9 so that the blade tip of blade 8 in combination with anvil 9 forms a small gap that facilitates fine comminution of cut material. This arrangement may comminute material down to a size of about 20 to 100 microns (compared to a typical cut material size of about 25 mm produced by a standard mulching mower).

When the mower is being advanced forward only anvil 9 is required to perform fine comminution. Anvil 10 is provided so that when the mower is pulled in reverse blades 8 and anvil 10 may perform comminution in a like manner. It will be appreciated that where a mower need only be operated in a forward direction only anvil 9 is required and anvil 10 may be dispensed with.

The airflow through the mower clears cut material from the housing and thus reduces the power of motor required. Cut grass is immediately transported by the strong airflow from the fan to the anvil, finely comminuted and dissipated in the ground - thus reducing the distance cut grass must be transported and avoiding grass build up at the top of the mower housing. For example a 4.5 horsepower motor may be used for a 28 inch cutting diameter compared to a conventional mulching mower which would typically require a motor of 10 horsepower or more. The airflow D exiting the housing at the periphery generates lift which avoids the need for support wheels, provides easy manoeuvrability and reduces the power required to move the mower.

Hover mowers also have minimal impact upon the surface being cut. The housing 1 may be formed of a rigid material such as plastics or metal but could be formed of a flexible material such as a fabric with a support structure as the airflow creates positive pressure to support a flexible housing.

Referring now to Figures 4 and 5 a multi cutting head mower is shown. The mower consists of a motor 1 1 supported on a wheeled chassis 12. Motor 1 1 drives pulleys 14 and 1 5 via drive belt 16. As in the previous embodiment openings 17 and 18 are provided to supply air to a fan attached to cutting heads 19 and 20. As in the previous embodiment anvils 21 to 24 are provided to facilitate comminution of cut material in the same manner as described. The operation of the mower is as described in relation to the previous embodiment except that regions 25 and 26 are provided to maintain consistent airflow through the housing. Cutting heads 19 and 20 are preferably arranged so that they overlap across the line of forward motion of the mower. In this way if cutting head 19 is the forward cutting head it will comminute cut material with anvil 24 when moved in the forward direction but if it cannot finely comminute all cut material this can be drawn in by cutting head 20 and be finely comminuted by the second cutting head 20 and anvil 21. Due to the overlap cutting head 20 has a smaller area to cut and so will have capacity to comminute cut material that cannot be comminuted by cutting head 19. The amount of overlap of the cutting diameters of cutting heads 19 and 21 may preferably be between about 10% to 25%. Cutting head 19 may also be of a smaller diameter than cutting head 20 in view of the overlap.

Referring now to Figure 6 there -is shown a mower having three cutting heads 28 to 30 positioned within housing 27. The operation of this mower is generally as described in relation to the previous embodiments. In this embodiment cutting head 28 is the forward cutting head when mowing in the forward direction so that cutting heads 29 and 30 overlap the cutting path of cutting head 28. Accordingly, cutting head 28 may be of a smaller diameter than cutting heads 29 and 30.

Referring now to Figure 7 a schematic diagram of an assembly of hover mowers is shown. Hover mowers 31 to 33 may have multiple cutting heads and generate lift sufficient to support the mower above the ground. An array of such other mowers 31 to 33 may be towed by vehicle 34 with the mowers powered by a power take off coupling 35 and power linkages 36 and 37 between mowers. Alternatively, a motor could be provided on each mower 31 to 33 so that it is independently powered. Such an arrangement can greatly reduce the power requirements of towing vehicle 34. As the mowers 31 to 33 are hover mowers they have minimal resistance to movement and so vehicle 34 may have a much lower power rating than for a mower of equivalent capacity. Further, the airflow of mowers 31 to 33 reduces the power required to drive the mowers, further reducing the required capacity of vehicle 34. It is envisaged that a small vehicle such as an ATV may be able to drive an array of the type shown in Figure 7 having a combined cutting width of about 3 to 9 meters.

Referring now to Figure 8 a trimmer is shown based on the mower design shown in Figures 1 to 3. Housing 1 shown in Figure 8 is of substantially the same design as the mower shown in Figure 2 except that motor 2 is not present and a motor 38 drives the cutting head via shaft 39 and pivotal coupling 40. Pivotal coupling 40 pivots about a substantially vertical plane along the driveshaft and does not allow lateral pivoting. The pivotal coupling is via a bevelled gear arrangement to allow free rotation in one plane without significant resistance to pivoting.

This allows the housing to pivot to follow contours whilst separately from the drive shaft preventing lateral rotation - which may be hazardous to an operator due to a lack of positive control.

Referring now to Figures 9 to 1 1 a hover mower is shown which incorporates a fan generating an "air curtain" (the flow indicated by arrows A) to keep the housing of the mower clear of cut material. Within housing 41 cutting head

42 and fan assembly 43 rotate relatively thereto. The blades of cutting head

42 are configured to generate lift to draw material to be cut towards the blades and to then draw cut material into the housing. As shown in Figure 12 the fan assembly consists of plate 44 having a plurality of inlets 45 about the periphery of the plate. As plate 44 rotates in an anticlockwise direction the inlets 45 direct air downwardly through apertures towards cutting head 42. The opposing flows from cutting head 42 and inlets 45 combine and centrifugal forces force the flow B outwardly towards the periphery of the housing 41. Fins 46 direct air through air intake 47 and outwardly to the periphery of that housing as indicated by arrows A. This air flow creates an air curtain about the periphery of the housing of greater pressure than the outward flow 13 which directs flow 13 towards the cutting region between the blades and anvil and stops cut material accumulating on the walls of the housing. This prevents clogging which would otherwise place an increased load on the mower. As seen in Figure 10 the cutting head 48 in this case is an open blade design allowing free air flow. This arrangement concentrates the majority of the air flow to the periphery to provide an air curtain to keep the housing clear and to enable hovering whilst the inlets 45 produce a lower volume of air towards the cutting head sufficient to keep the plate clear of cut material but not such as to disperse cut material before it is comminuted between blade 48 and anvil 49.

The air flow path within the mower draws cut material in and directly conveys it to the cutting region between the blades and anvil to micronize the cut material. This reduces the dwell time of cut material within the housing to a minimum and reduces clogging.

Referring now to Figures 13 and 14 a strimmer design is shown. Air enters via inlet 51 and fan 52 direct air towards, the periphery of the housing 50.

Although not shown the strimmer includes an anvil of the type shown in the previous embodiment about the periphery of cutting head 53.

Figures 15 to 17 show a dual cutting head mower in which the cutting heads 55 and 56 overlap. Each cutting head 55 and 56 has an associated anvil 57 and 58 as shown in Figure 16. Referring now to Figure 17 it will be seen that air enters through the top of the housing 54 via inlets 59 and 60 and is directed outwardly about the periphery of the housing by fans 61 and 62 to create an air curtain to about the periphery of the housing which keeps the housing clear of cut material and directs cut material between the cutting heads and anvils. The fans 61 and 62 are of the form shown in Figure 12 so that the blades of the cutting head draw cut material into the housing, the inlets (45 in Figure 12) provide a moderate air flow towards the blades whilst the majority of air flow is directed about the periphery of the housing.

Referring now to Figures 18 to 20 a mower according to- a further embodiment is shown. The mower includes three tubular housings 63, 64 and 65 having blades 66, 67 and 68 and fans 69, 70 and 71 mounted within each tubular housing. As shown in Figure 20 tubular housing 64, by way of example, has an open end 72 as the air intake and a fan 64 and blade 67 rotating within the tubular housing. The tubular housing has anvil sections 73 and 74 and openings 75 therebetween to provide good airflow. In this case fan 64 consists simply of the plate 44 as shown in Figure 12 (i.e. without fins 46). The inlets produce a downward air flow which directs cut material lifted by blade 67 towards the periphery of the cutting head and wall of housing 64. This arrangement provides an extremely simple construction capable of finely comminuting cut material between blade 67 and housing 64.

Figure 21 shows a perspective view of an integrally formed anvil ring 76.

The anvil ring includes anvil portions 77 and 78 with openings 79 and 80 therebetween to provide stable air and grass flow, opening 79 allows grass that has not been comminuted to exit. 80 allows the uncut grass to move easily into the cutting housing. This construction has the advantage of simple manufacture and the anvil ring 76 may be integrally formed with the housing. Both the anvil ring 76 and housing may be formed from a variety of suitable materials and may be simultaneously formed of moulded plastics.

Figures 22 and 23 show a dual fan embodiment in which the fan 81 has a series of fins 82 on the upper side and fins 83 on its lower side. If fan 81 is substituted with, for example fan 83 as shown in Figure 11 , then fins 82 produce an air curtain as described in relation to Figure 1 1 whilst fins 83 provide an air flow outwardly to clear cut material directed towards the fan by the blades.

The above embodiments confer the following advantages:

1. Cut material is transported through the housing so as to minimise dwell time of cut material within the mower and to avoid a build up of cut material on the interior of the housing to clog the mower. The "air curtain" assists in conveying material away from the walls of the housing and towards the periphery of the cutting head.

2. Cut material is comminuted to a small size (about 20 to 100 microns compared to about 25mm plus in normal mulching mower) so that it is easily broken down and used by the soil and does not leave large pieces to be picked up on shoes etc. Grass that is not comminuted takes a long time to decompose; this process attracts insects like flies. The decomposing grass causes an array of gases to be released which is claimed to be one of the causes of global warming. 3. Reduced power requirements (It has been found that power requirements may be reduced in excess of 50%, for example a 4.5Hp motor may be used for a 28 inch mower compared to a motor size of

10Hp plus normally required for a mulching mower).

4. A lighter and more manoeuvrable mower due to simple construction and reduced engine size. 5. Hover mowers require less towing force and so a smaller towing vehicle may be used.

6. Hover mowers have a low impact upon the surface being cut.

7. For a trimmer free pivoting in the plane of the drive shaft allows the mower to float over the terrain allowing positive control of the mower without slop - thus improving cut quality and handling. The invention allows for pivoting of the trimmer head which allows it to float vertically up and downwards during forward, sideward and rear motion. This allows the trimmer head to float parallel to the ground irrespective of the drive shaft position. Being a positive control, it is not hazardous for the operator.

While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant's general inventive concept.

Claims

CLAIMS:

1 . A lawn mower including: a. a housing having an open underside face and an air intake; b. a cutting head rotatably mounted within the housing including a plurality of blades wherein the blades are arranged to draw air and material to be cut from below the underside face of the housing into the housing; and c. a fan arranged to draw air into the housing through the air intake, the arrangement being such that air and cut material drawn into the housing through the cutting head is transported upwardly within the housing and air drawn into the housing through the air intake transports the cut material downwardly and outwardly to the periphery of the cutting head.

2. A lawn mower as claimed in claim 1 including an anvil extending at least partially around the periphery of open face of the housing spaced apart from the blades to contain cut material and facilitate comminution of cut material.

3. A lawn mower as claimed in claim 2 including a single anvil extending partially around the periphery of open face of the housing.

4. A lawn mower as claimed in claim 3 wherein the anvil extends around about a quarter of the periphery of the cutting head.

5. A lawn mower as claimed in claim 4 wherein the anvil extends between about 60 degrees to 150 degrees with respect to the direction of forward movement of the mower.

6. A lawn mower as claimed in any one of claims 2 to 5 including a second anvil extending partially around the periphery of the open face of the housing spaced apart from the blades so as to comminute cut material passing therebetween.

7. A lawn mower as claimed in claim 6 wherein the second anvil extends around about a quarter of the periphery of the cutting head.

8. A lawn mower as claimed in claim 7 wherein the second anvil extends between about 240 degrees to 330 degrees with respect to the direction of forward movement of the mower.

9. A lawn mower as claimed in any one of the claims 2 to 8 wherein the gap between the blades and each anvil is between 1 to 6mm.

10. A lawn mower as claimed in any one of the claims 2 to 8 wherein the gap between the blades and each anvil is about 3mm.

1 1 . A lawn mower as claimed in any one of the preceding claims wherein the fan is mounted to the cutting head.

12. A lawn mower as claimed in claim 1 1 wherein the fan is a centrifugal fan having backward drag or straight blades that produces an airflow directed downwardly, outwardly and rotationally in the direction of rotation of the cutting head.

13. A lawn mower as claimed in claim 12 wherein the fin height of the fan is between 8% to 20% of the diameter of the cutting head.

14. A lawn mower as claimed in claim 1 1 or claim 12 wherein the fan ' intake is provided in the top of the housing and is between 1 5% to 30% of the diameter of the cutting head.

15. A lawn mower as claimed in any one of the preceding claims wherein the blades are shaped and oriented to generate lift.

16. A lawn mower as claimed in any one of the preceding claims wherein the blades are removable.

17. A lawn mower as claimed in any one of the preceding claims wherein the housing includes regions between the cutting head and the periphery of the housing dimensioned and arranged to maintain consistent and positive downward air pressure and airflow through the housing enabling the mower to hover.

18. A lawn mower as claimed in claim 1 7 wherein the housing is generally rectangular.

19. A lawn mower as claimed in claim 18 wherein a pair of cutting heads are positioned near opposite corners of the housing.

20. A lawn mower as claimed in any one of the preceding claims wherein a pair of cutting heads are provided and arranged such that their cutting paths overlap in use.

21 . A lawn mower as claimed in claim 20 wherein the cutting heads overlap by about 10% to 25%.

22. A lawn mower as claimed in any one of claims 19 to 21 wherein the housing has a forward end in the normal direction of mowing and one cutting head is positioned towards the forward end and has a smaller diameter than the other cutting head.

23. A lawn mower as claimed in any one of the preceding claims wherein three or more cutting heads are provided and arranged such that their cutting paths overlap in use.

24. A lawn mower as claimed in claim 23 wherein the housing has a forward end in the normal direction of mowing and one or more cutting heads are positioned towards the forward end and the other cutting heads are positioned to either side behind the one or more cutting heads.

25. A lawn mower as claimed in claim 24 wherein the cutting head that is positioned towards the forward end has a smaller diameter than the other cutting heads.

26. A mower as claimed in any one of the preceding claims wherein the mower is a hover mower.

27. A mower as claimed in any one of the preceding claims wherein the mower is a trimmer.

28. An array of mowers as claimed in any one of the preceding claims linked together in a towable array.

29. An array of mowers as claimed in claim 28 wherein each mower has an independently driven motor.

30. An array of mowers as claimed in claim 28 wherein the mowers are driven via a drive linkage adapted to engage with a vehicle power take off coupling.

31. A hover mower including: a. a housing having an open underside face and an air intake; b. a fan arranged to draw air into the housing through the air i ntake; c. a cutting head rotatably mounted within the housing including a plurality of blades; and d. an anvil extending at least partially around the periphery of the open face of the housing spaced apart from the blades so as to facilitate comminution of cut material.

32. A hover mower as claimed in claim 31 having regions between the cutting head and the periphery of the housing dimensioned and arranged to maintain consistent airflow through the housing.

33. A hover mower as claimed in claim 31 or claim 32 including a single anvil extending partially around the periphery of open face of the housing.

34. A hover mower as claimed in claim 33 wherein the anvil extends around about a quarter of the periphery of the cutting head.

35. A hover mower as claimed in claim 34 wherein the anvil extends between about 60 degrees to 150 degrees with respect to the direction of forward movement of the mower.

36. A hover mower as claimed in any one of claims 32 to 35 including a second anvil extending partially around the periphery of the open face of the housing spaced apart from the blades so as to comminute cut material passing therebetween.

37. A hover mower as claimed in claim 36 wherein the second anvil extends around about a quarter of the periphery of the cutting head.

38. A hover mower as claimed in claim 37 wherein the second anvil extends between about 240 degrees to 330 degrees with respect to the direction of forward movement of the mower.

39. A hover mower as claimed in any one of the claims 32 to 38 wherein the gap between the blades and each anvil is between 1 to 6mm.

40. A hover mower as claimed in any one of the claims 32 to 38 wherein the gap between the blades and each anvil is about 3mm.

41 . A hover mower as claimed in any one of claims 31 to 40 wherein the fan is mounted to the cutting head.

42. A hover mower as claimed in claim 41 wherein the fan is a backward drag centrifugal fan.

43. A hover mower as claimed in claim 42 wherein the fin height of the fan is between 8% to 20% of the diameter of the cutting head.

44. A hover mower as claimed in claim 41 or claim 42 wherein the fan intake is between 15% to 30% of the diameter of the cutting head.

45. A hover mower as claimed in any one of claims 31 to 44 wherein the blades are shaped and oriented to generate lift.

46. A hover mower as claimed in any one of claims 31 to 45 wherein the blades are removable.

47. A hover mower as claimed in any one of claims 31 to 46 wherein the housing includes regions between the cutting head and the periphery of the housing dimensioned and arranged to maintain consistent airflow through the housing.

48. A hover mower as claimed in claim 47 wherein the housing is generally rectangular.

49. A hover mower as claimed in claim 48 wherein a pair of cutting heads are positioned near opposite corners of the housing.

50. A hover mower as claimed in any one of claims 31 to 49 wherein a pair of cutting heads are provided and arranged such that their cutting paths overlap in use.

51. A hover mower as claimed in claim 50 wherein the cutting heads overlap by about 10% to 25%.

52. A hover mower as claimed in any one of claims 49 to 51 wherein the housing has a forward end in the normal direction of mowing and one cutting head is positioned towards the forward end and has a smaller diameter than the other cutting head.

53. A hover mower as claimed in any one of claims 31 to 52 wherein three cutting heads are provided and arranged such that their cutting paths overlap in use.

54. A hover mower as claimed in claim 53 wherein the housing has a forward end in the normal direction of mowing and one cutting head is positioned towards the centre of the forward end and the other cutting heads are positioned to either side behind the one cutting head.

55. A hover mower as claimed in claim 54 wherein the cutting head that is positioned towards the forward end has a smaller diameter than the other cutting heads.

56. A mower as claimed in any one of claims 31 to 55 wherein the mower is a trimmer.

57. An array of mowers as claimed in any one of claims 31 to 56 linked together in a towable array.

58. An array of mowers as claimed in claim, 57 wherein each mower has an independently driven motor.

59. An array of mowers as claimed in claim 59 wherein the mowers are driven via a drive linkage adapted to engage with a vehicle power take off coupling.

60. A mower as claimed in any one of the preceding claims wherein the housing is formed of fabric.

61 . A hover mower including: a. a housing having an open underside face and an air intake; b. a fan arranged to draw air into the housing through the air intake; c. a cutting head rotatably mounted within the housing including a plurality of blades; and d. a drive shaft coupled to the cutting head by a freely pivoting coupling allowing substantially free pivoting forward and aft.

62. A hover mower as claimed in claim 61 wherein the pivoting coupling pivots about a substantially vertical plane along the drive shaft.

63. A hover mower as claimed in claim 61 or claim 62 wherein the pivoting coupling includes gears to couple the drive shaft to the cutting head.

64. A hover mower as claimed in claim 63 wherein the gears are bevel gears.

65. A hover mower as claimed in any one of claims 61 to 64 including an anvil extending at least partially around the periphery of the open face of the housing spaced apart from the blades so as to facilitate comminution of cut material.

66. A hover mower as claimed in claim 65 having regions between the cutting head and the periphery of the housing dimensioned and arranged to maintain consistent airflow through the housing.

67. A hover mower as claimed in claim 65 or claim 66 including a single anvil extending partially around the periphery of open face of the housing.

68. A hover mower as claimed in claim 67 wherein the anvil extends around about a quarter of the periphery of the cutting head.

69. A hover mower as claimed in claim 68 wherein the anvil extends between about 60 degrees to 150 degrees with respect to the direction of forward movement of the mower.

70. A hover mower as claimed in any one of claims 67 to 69 including a second anvil extending partially around the periphery of the open face of the housing spaced apart from the blades so as to comminute cut material passing therebetween.

71 . A hover mower as claimed in claim 70 wherein the second anvil extends around about a quarter of the periphery of the cutting head.

72. A hover mower as claimed in claim 71 wherein the second anvil extends between about 240 degrees to 330 degrees with respect to the direction of forward movement of the mower.

73. A hover mower as claimed in any one of the claims 67 to 72 wherein the gap between the blades and each anvil is between 1 to 6mm.

74. A hover mower as claimed in any one of the claims 67 to 72 wherein the gap between the blades and each anvil is about 3mm.

75. A hover mower as claimed in any one of claims 66 to 74 wherein the fan is mounted to the cutting head.

76. A hover mower as claimed in claim 75 wherein the fan is a backward drag centrifugal fan.

77. A hover mower as claimed in claim 76 wherein the fin height of the fan is between 8% to 20% of the diameter of the cutting head.

78. A hover mower as claimed in claim 76 or claim 77 wherein the fan intake is between 15% to 30% of the diameter of the cutting head.

79. A hover mower as claimed in any one of claims 61 to 78 wherein the blades are shaped and oriented to generate lift.

80. A hover mower as claimed in any one of claims 61 to 79 wherein the blades are removable.

81. A hover mower as claimed in any one of claims 61 to 80 wherein the housing includes regions between the cutting head and the periphery of the housing dimensioned and arranged to maintain consistent airflow through the housing.

82. A mower as claimed in any one of claims 61 to 81 wherein the mower is a trimmer.

83. A mower as claimed in any one of the preceding claims wherein the fan generates an air curtain about the periphery of the housing which directs cut material away from the housing and towards the periphery of the cutting head.

84. A mower as claimed in claim 83 wherein the fan extends to or near the periphery of the cutting head.

85. A mower as claimed in claim 83 or 84 wherein the fan includes a plate between the fan and the cutting head,

86. A mower as claimed in claim 85 wherein the plate has a plurality of apertures towards the periphery of the plate.

87. A mower as claimed in claim 86 wherein the apertures have raised inlets to direct airflow downwardly towards the cutting head.

88. A mower as claimed in any one of claims 85 to 87 wherein the plate rotates with the fan.

89. A mower as claimed in any one of claims 85 to 87 wherein the plate is stationary.

90. A mower as claimed in any one of claims 85 to 89 including a fan below the plate which generates an airflow outwardly towards the periphery of the cutting head.

91. A mower as claimed in any one of claims 2 to 30 when dependent upon claim 2 or any one of claims 31 to 60 wherein each anvil is integrally formed as part of a ring about the periphery of the cutting head.

92. A mower as claimed in claim 91 wherein the ring is integrally formed with the housing.

93. A mower as claimed in claim 91 or claim 92 wherein the ring is formed of plastics.

94. A mower including: a. a tubular housing having an air intake at one open end and an open underside face at the other end; b. a fan arranged to draw air into the housing through the air intake; c. a cutting head rotatably mounted within the housing including a plurality of blades; and d. an anvil extending at least partially around the periphery of the open face of the housing spaced apart from the blades so as to facilitate comminution of cut material.

95. A mower as claimed in claim 94 wherein the fan is in the form of a plate mounted above the cutting head having a plurality of raised inlets which when rotated with the cutting head generates a downward airflow.

96. A mower as claimed in claim 95 wherein the raised inlets are provided towards the periphery of the plate.

97. A mower as claimed in any one of claims 94 to 96 including a single anvil extending partially around the periphery of the underside face of the housing.

^■ 98. A mower as claimed in claim 97 wherein the anvil extends around about a quarter of the periphery of the cutting head.

99. A mower as claimed in claim 98 wherein the anvil extends between about 60 degrees to 150 degrees with respect to the direction of forward movement of the mower.

100. A mower as claimed in any one of claims 97 to 99 including a second anvil extending partially around the periphery of the open face of the housing spaced apart from the blades so as to comminute cut material passing therebetween.

101 . A mower as claimed in claim 100 wherein the second anvil extends around about a quarter of the periphery of the cutting head.

102. A mower as claimed in claim 101 wherein the second anvil extends between about 240 degrees to 330 degrees with respect to the direction of forward movement of the mower.

103. A mower as claimed in any one of the claims 97 to 102 wherein the gap between the blades and each anvil is between 1 to 6mm.

104. A mower as claimed in any one of the claims 97 to 102 wherein the gap between the blades and each anvil is about 3mm.

105. A mower as claimed in any one of claims 94 to 104 wherein the fan is mounted to the cutting head.

106. A mower assembly comprising a plurality of mowers as claimed in any one of claims 94 to 105.

107. A mower as claimed in any one of the preceding claims configured to comminute cut material to a size of between 20 to 100 microns.