CN103796503B

CN103796503B - Grass cutter

Info

Publication number: CN103796503B
Application number: CN201180073423.0A
Authority: CN
Inventors: 史密斯艾安·泽特尔斯特罗梅尔; 罗格·托马斯
Original assignee: Husqvarna UK Ltd
Current assignee: Husqvarna UK Ltd
Priority date: 2011-09-13
Filing date: 2011-09-13
Publication date: 2020-06-19
Anticipated expiration: 2031-09-13
Also published as: GB2513452B; WO2013038121A1; CN103796503A; GB201403208D0; GB2513452A

Abstract

A lawnmower, typically a lawnmower, comprising: a casing (1) open at its bottom face (2) and defining on it a cutting chamber (3) and a lifting chamber (4); a cutting element (6) located in the cutting chamber; and a lifting force generating member (8) located in the lifting chamber (4); wherein the cutting element (6) and the lifting force generating member (8) are mounted for rotation about a substantially vertical axis (7, 9) substantially perpendicular to the bottom surface (2).

Description

Grass cutter

The present invention relates to lawn mowers.

In the prior art, suspension mowers are well known. Typically, a suspension mower includes a housing defining a suspension chamber open at a bottom surface in which an impeller, which generates a layer of pressurized air that is forced downward to generate lift, and a cutting blade that rotates about a vertical axis, operate.

It has been proposed to provide a suspended mower with a separate chamber for generating lift and for mowing; in the uk patent application published as GB 2318966, this is done to assist in the collection of grass. In this example, the rotary blade is provided in a cutting chamber at the front of the mower and a lift chamber is provided at the rear of the mower, the lift chamber having pressurized air by means of a duct system. The impeller is a source of pressurized air, driven directly by the motor shaft, and therefore must be driven at the operating speed of the motor. The motor is provided above the lift chamber and is surrounded by the grass box.

According to a first aspect of the present invention, there is provided a lawnmower comprising: a housing which is open at a bottom surface thereof and defines a cutting chamber and a lifting chamber at the bottom surface; a cutting element located in the cutting chamber; and a lifting force generating member located in the lifting chamber, wherein the cutting element and the lifting force generating member are mounted for rotation generally about a vertical axis that is generally perpendicular to the bottom surface.

This represents an improvement over prior art two-chamber suspension mowers in that the lift force generating member is placed in the lift chamber rather than relying on ducted airflow. Placing the lifting force producing member in the lifting chamber allows for the use of a larger, quieter lifting force producing member which otherwise could not be achieved and allows for a greater choice of lifting force producing members to be used, thus allowing for the selection of lifting force producing members from a broader group because the lifting chamber can be sized appropriately, allowing for the lifting force producing members to be optimally designed in terms of flow, velocity, and noise.

The lift force generating member may comprise an impeller (such as a mixed flow fan). It has been found that such a fan is quieter than prior art fans.

Typically, a lawn mower will include a motor having an output shaft. Preferably, the mower will comprise a lift transmission having an input rotatable about a first lift transmission axis and an output rotatable about a second lift transmission axis, the first and second lift transmission axes being spaced from one another, the input being coupled to the output so as to transmit rotation of the input to rotate the output, the input being coupled to an output shaft of the motor and the output being coupled to the lift force generating member. This therefore allows the lifting force generating member to be spaced from the motor.

Similarly, the mower may include a cutting transmission having an input rotatable about a first cutting transmission axis and an output rotatable about a second cutting transmission axis, the first cutting transmission axis and the second cutting transmission axis being spaced apart from one another, the input coupled to the output so as to transmit rotation of the input to rotate the output, the input coupled to the output shaft of the motor and the output coupled to the cutting element.

At least two of the first and second cutting drive axes and the first and second lift drive axes may be parallel. Typically, the first cutting drive axis and the first lifting drive axis will be coincident and coincident with the output shaft of the motor. The second cutting drive axis may coincide with a vertical axis of the cutting element, and the second lifting drive axis may coincide with a vertical axis of the lifting force generating member.

By having both the lifting force generating member and the cutting element driven by their respective transmissions (motors), the lifting force generating member, the cutting element and the motor can be spaced apart at desired locations in the housing. It is no longer necessary to have a motor, for example, coaxial with the lifting force generating member, and therefore a relatively heavy motor can be placed at a desired place to achieve a desired mass distribution.

This means that the motor can be moved forward, for example, to allow a larger grass box to be provided, compared to prior art lawnmowers. Therefore, the motor may be disposed closer to the center of the extending direction of the housing than to the edge of the extending direction of the housing in the horizontal plane. Typically, the motor will not be surrounded by any part of the grass box of the mower.

The cutting element may be mounted on a cantilevered member secured to the housing at a mounting point remote from the cutting element; the bending of at least one of the housing and the cantilevered member allows the cutting element to move relative to the housing generally along a vertical axis of the cutting element.

This therefore provides a convenient way of allowing the cutting element to be height adjusted without the user having to re-secure the cutting element. Furthermore, since the lifting force generating member can be mounted around the mounting point, there is no need to move the lifting force generating member together with the cutting element; in prior art systems, the lifting force generating member is mounted coaxially with the cutting element, moving the shaft on which the cutting element is mounted would necessarily move the lifting force generating member. Doing so may impair the function of the lifting force generating members, since they are generally adapted to work in a certain position with respect to the housing of the lawn mower and with some clearance from the housing of the lawn mower.

Movement of the cutting element generally along the vertical axis of the cutting element will typically not be perfectly linear, but will include a component of pivotal movement about a point near the mounting point. However, because the mounting point is remote from the cutting element, the movement will typically be approximately linear.

The mower may further comprise an adjuster that drives bending of at least one of the cantilever and the housing to move the cutting element. The adjuster can be manipulated by the user using the lowermost floor. Thus, the user does not have to turn the mower over when adjusting the cutting height. The adjuster may include a crank bar having a crank portion that operates in a slot in the cantilever member, rotation of the crank bar causing movement of the cantilever arm relative to the housing.

The lawn mower may further comprise a locking mechanism whereby the position of the cantilever arm relative to the housing can be fixed, thereby fixing the position of the cutting element relative to the housing along the vertical axis of the cutting element. The adjuster may include a locking mechanism which may include a rod secured to the crank bar, typically biased against the housing. Typically, the adjuster will have a plurality of discrete positions, the adjuster locking the position of the cutting element at a plurality of discrete positions along the vertical axis of the cutting element; the discrete positions may be defined by detents in the housing.

The cantilevered members may support the motor and typically also the lift and cutting actuators. Typically, the lifting force generating member will be mounted about the mounting point, with the motor mounted between the lifting force generating member and the cutting element.

The cutting chamber may be provided with a suction source whereby cut grass can leave the cutting element. This replaces prior art systems in which grass is thrown off the blade and blown away by the air diverting portion of the cutting element; by providing a suction source, the present invention is able to provide a reduction in the amount of cut grass adhering to the inner walls of the cutting chamber. By sucking air from the cutting chamber instead of blowing air out of it, the mower can also be made more resistant to clogging in the path of the grass.

Typically, a lawn mower will include a path for directing cut grass from the cutting element toward a suction source. A lawn mower will typically include a grass box that may represent the end of the path away from the cutting element. Preferably, the path will be straight, thus avoiding that grass is sucked around the corner and thus accumulates on the wall of the corner.

The suction source may include a lifting force generating member; air can thus be sucked (usually indirectly) from the cutting chamber to the lifting chamber, usually via the grass box. The grass box may have perforated walls that will at least partially obstruct the flow of cut grass, but allow air flow.

Whilst the housing is open on the bottom surface, the housing surrounding the cutting chamber may be provided with at least one aperture therein to allow airflow into the cutting chamber. This is particularly useful when a source of suction is provided, as it provides a relief for negative pressure which would otherwise build up and thus reduce the tendency of the cutting chamber to be sucked towards the ground. The or each aperture may be located above the cutting element (i.e. they may be located on the distal side of the cutting element remote from the base surface).

To avoid objects protruding from the cutting element through the or each hole, a wall may be provided in the cutting chamber between the or each hole and the cutting element. The wall may physically separate the cutting element from the or each aperture but allow airflow from the or each aperture through the cutting element; the wall may therefore define a bend in the path of air between the or each aperture and the cutting element.

Generally, the wall may be in the form of a portion of a cylindrical surface, typically coaxial with the cutting element. Such walls provide a smooth and continuous collection area for cut grass within the cutting chamber, reducing the amount of cut grass adhering to the inner walls of the cutting chamber.

The lawn mower may be provided with a handle comprising a portion arranged to be gripped by a user, the handle being mounted on the housing by means of an elastic coupling which tends to bias the housing to lift the cutting chamber with the bottom surface located lowermost.

Thus, by providing a resilient coupling, the tendency of the cutting chamber to tilt towards the ground is at least partially ameliorated, either due to the suction source or simply because the lifting force generating member tends to lift the lifting chamber rather than the cutting chamber. Furthermore, the resilient coupling may tend to balance the weight of the handle, thus providing a handle that feels light in the user's hand.

Typically, with the lowermost bottom surface, the handle is pivotable relative to the housing about the elastic coupling about a horizontal axis. The resilient coupling may apply a biasing torque about the horizontal axis. Typically, the handle may have only a single degree of rotational freedom relative to the housing.

Preferably, the resilient coupling will comprise a torsion spring, although it is also possible to use an extension spring or a compression spring.

In the case where the cutting chamber is located at the front of the housing and the lifting chamber is located at the rear of the housing (typically the front being furthest from the second portion), the resilient coupling will generally tend to tilt the front of the housing upwards.

According to a second aspect of the present invention, there is provided a lawnmower comprising: a housing which is open at a bottom surface thereof and defines a cutting chamber; a cutting element located in the cutting chamber, mounted for rotation about a substantially vertical axis; and a cantilevered member on which the cutting element is mounted; the cantilevered member is secured to the housing at a mounting point distal from the cutting element; the bending of at least one of the housing and the cantilevered member allows the cutting element to move relative to the housing generally along a vertical axis of the cutting element.

This therefore provides a convenient way of allowing height adjustment of the cutting element without the user having to re-secure the cutting element.

Movement of the cutting element generally along the vertical axis of the cutting element will typically not be perfectly linear, but will contain a component of pivotal motion about a point close to the mounting point. However, because the mounting point is remote from the cutting element, the movement will typically be approximately linear.

The lawn mower may further comprise an adjuster that drives bending of at least one of the cantilever and the housing to move the cutting element. The adjuster can be manipulated by the user using the lowermost floor. Thus, the user does not have to turn the mower over when adjusting the cutting height. The adjuster may comprise a crank bar having a crank portion which operates in a slot in the cantilever member, rotation of the crank bar causing movement of the cantilever relative to the housing.

The lawn mower may further comprise a locking mechanism whereby the position of the cantilever arm relative to the housing can be fixed, thereby fixing the position of the cutting element relative to the housing along the vertical axis of the cutting element. The adjuster may include a locking mechanism that may include a rod secured to the crank bar, typically biased against the housing. Typically, the adjuster will have a plurality of discrete positions at which the adjuster locks the position of the cutting element along the vertical axis of the cutting element; the discrete positions may be defined by locators in the housing.

The cantilever member may support a motor of the mower.

The mower may include a cutting transmission having an input rotatable about a first cutting transmission axis and an output rotatable about a second cutting transmission axis, the first cutting transmission axis and the second cutting transmission axis being spaced apart from one another, the input coupled to the output so as to transmit rotation of the input to rotate the output, the input coupled to an output shaft of the motor and the output coupled to the cutting element, the cutting transmission also being supported by the cantilevered member.

The housing may further define a lifting chamber, the lawn mower comprising a lifting force generating device arranged to generate a lifting force in the lifting chamber. The lifting force generating means may comprise a lifting force generating member in the lifting chamber.

The mower may be according to the first aspect of the present invention and may have any of the optional features described above.

According to a third aspect of the present invention, there is provided a lawnmower comprising: a housing which is open at a bottom surface thereof and defines a cutting chamber and a lifting chamber on the bottom surface; a cutting element located in the cutting chamber; and a lifting force generating device arranged to generate a lifting force in the lifting chamber, the housing surrounding the cutting chamber being provided with at least one aperture to allow airflow into the cutting chamber.

This provides relief against any negative pressure that would otherwise build up in the cutting chamber and thus reduce the tendency of the cutting chamber to be sucked towards the ground. This is particularly useful in case the cutting chamber is provided with a suction source, whereby cut grass can leave the cutting element.

The or each aperture may be located above the cutting element (i.e. they may be located on the distal side of the cutting element remote from the base surface).

Typically, the wall may be in the form of a portion of a cylindrical surface, typically coaxial with the cutting element. Such walls provide a smooth and continuous collection area for cut grass within the cutting chamber, reducing the amount of cut grass adhering to the inner walls of the cutting chamber.

The lifting force generating means may comprise a lifting force generating member located in the lifting chamber. The lawn mower may be in accordance with any of the above aspects of the invention and may have any of the optional features described herein.

According to a fourth aspect of the present invention, there is provided a lawnmower comprising: a housing which is open at a bottom surface thereof and defines a cutting chamber on the bottom surface; a cutting element located in the cutting chamber; and a handle comprising a portion arranged for grasping by a user, the handle and the housing being connected together by a resilient coupling which, through a lowermost bottom surface, tends to bias the housing to lift the cutting chamber.

Thus, by providing a resilient coupling, any tendency of the cutting chamber to tilt towards the ground is at least partially ameliorated. This tendency may for example be due to the lifting chamber being provided on the floor separately from the cutting chamber, or due to the suction source being provided in the cutting chamber, or simply because the mower is not perfectly balanced. Furthermore, the resilient coupling may tend to be weight balanced for the handle, thus providing a handle that feels light in the user's hand.

The handle is pivotable relative to the housing about the resilient coupling; typically, with the lowermost floor, pivoting is usually about a horizontal axis. The resilient coupling may apply a biasing torque about the horizontal axis.

Preferably, the resilient coupling will comprise a torsion spring, although either an extension spring or a compression spring may be used.

Where the cutting chamber is located at the front of the housing and the lifting chamber is located at the rear of the housing (typically the front being furthest from the second portion), the resilient coupling will generally tend to tilt the front of the housing upwards.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a front elevation view of a lawn mower according to an embodiment of the present invention;

FIG. 2 shows a vertical cross-sectional view through the lawn mower of FIG. 1, taken along line A-A of FIG. 1;

FIG. 3 shows a vertical cross-sectional view through the lawn mower of FIG. 1, taken along line B-B of FIG. 1;

FIG. 4 shows a bottom side plan view of the lawn mower of FIG. 1;

FIG. 5 shows a perspective view of the drive system of the lawn mower of FIG. 1 from the top thereof;

FIG. 6 shows a perspective view of the transmission system of FIG. 5 from a bottom side thereof;

FIGS. 7 and 8 show partial cross-sectional views of the lawn mower of FIG. 1 taken along line A-A of FIG. 1, showing the cantilever motor mounting plate in two extreme adjustment positions; and

fig. 9 shows a partial cross-sectional view of the front of the lawn mower of fig. 1, showing airflow through the holes in the housing.

A lawn mower according to an embodiment of the present invention is shown in the drawings. The mower is a suspended mower. The lawn mower includes: a housing 1 which is open on a bottom surface 2 thereof; in use, this surface will be lowermost, facing the grass to be cut. The housing 1 defines two open chambers on the bottom surface 2: a cutting chamber 3 and a lifting chamber 4. The housing 1 also supports a handle 5 which can be grasped by a user.

A handle 5 is attached to the housing at the rear of the housing; in use, a user will walk behind the mower pushing it in through the rearmost handle 5.

The cutting chamber 3 is at the front of the mower and contains a cutting element (which is a rotary blade) 6. The blade 6 is rotatably mounted on a substantially vertical (relative to the ground and the floor 2 above the ground) axis 7. The cutting chamber is generally circular in profile (as shown in the plan view of figure 4 of the drawings) so as to surround the blade 6 but leave some clearance.

A lift chamber 4 is located behind the cutting chamber 3, at the rear of the mower. A lifting force generating member in the form of an impeller 8 is mounted for rotation about a generally vertical (relative to the ground and the floor 2 above the ground) axis 9. The impeller 8 is a mixed flow fan which has the advantage of being particularly quiet in operation.

In fact, the fact that the impeller 8 is mounted in the lifting chamber 4 and runs at a different speed to the blades and the motor output shaft allows a wider choice of impellers to be selected than if the impellers were running directly with the motor output and are therefore limited to a specific operating speed. Furthermore, because the impeller provides the airflow where it is needed, the inherent loss of locating the impeller in a chamber remote from the lift chamber and delivering the airflow into that chamber is greatly reduced.

The blade 6 and impeller 8 are driven to rotate about their

respective axes

7,9, as described below. The cutting element 6 and the impeller 8 can be driven at different speeds to perform their respective functions. The blade 6 will cut the grass and the impeller will force a layer of air downwards, thus lifting the mower off the grass to easily move the mower.

To drive the blade 6 and impeller 8, a drive train 10 is provided, shown in more detail in figures 5 and 6 of the drawings. The drive train 10 includes a central electric motor 11 mounted on an elongate mounting plate 12. The motor 11 has an output shaft 13, and energizing the motor 11 causes the output shaft 13 to rotate.

The mounting plate 12 supports two

pulleys

14, 15, one at each end of the mounting plate; each pulley is free to rotate relative to the mounting plate 12. Each

pulley

14, 15 is connected to the output shaft 13 by a

belt

16, 17. The

belts

16, 17 and pulleys 14, 15 thus represent two belt drives, so that rotation of the output shaft 13 is transmitted to the

pulleys

14, 15. Note that the

pulleys

14, 15 have different diameters, which means that for a given rotational speed of the output shaft 13, the rotational speed at which the pulleys rotate will be different. The belt drive transmits the rotation of the output shaft about axis 18 to the axes of

rotation

19, 20 of

pulleys

14, 15;

axes

19, 20 are spaced from axis 18.

The blade 6 will be mounted on the main shaft 21 of the pulley 15 and the impeller 8 will be mounted on the main shaft 22 of the pulley 14. The pulley 15 is larger than the pulley 14, which means that the impeller 8 coupled to the smaller pulley will rotate faster than the blade 6. Furthermore, the axis 19 will coincide with the vertical axis 7, while the axis 20 will coincide with the vertical axis 9.

As can be observed from fig. 7 and 8 of the drawings (not shown in the other drawings), this arrangement allows the motor 11 to be located in the centre of the casing 1; assuming that the motor 11 is one of the heaviest parts of the mower, being able to locate the motor 11 in the centre of the housing (rather than, say, above the lift chamber 4) means that a more balanced mower results.

A mounting plate 12 is fixed to the casing 1 and at the end carrying a pulley 14 coupled to the impeller; the fixing lug 39 will be fixed to the housing using screws. Although this means that the impeller end of the mounting plate is fixed relative to the housing 1, both the housing 1 and the mounting plate 12 are flexible to some extent. This means that the mounting plate 12 is cantilevered to the housing 1 and therefore the blade end can move freely in a near vertical manner.

This can be used to allow the height of the blade 6 relative to the housing to be adjusted and thus at which height the grass will be cut. A lever 23 is provided supported on the housing 1 so as to bias the housing against the plurality of detents to provide a plurality of fixed positions of the lever. The lever 23 includes a shaft 38 having a crank portion 37 that operates in the slot 24 in the mounting plate 12. Rotation of the lever 23 about the axis 38 causes the crank portion 37 to force the end of the blade 6 of the mounting plate 12 to be driven up or down by the crank portion of the lever 23. Thus, the height of the blade 6 can be easily adjusted by a user without having to invert the mower or access the bottom side (which is typically dirty) or in any way physically contact the blade.

The mower further comprises a removable grass box 24. The grass box 24 has a perforated bottom side 36 which is located above the impeller 8 when the grass box 24 is placed on the mower. When rotated by the motor 11, the impeller 8 draws air from the grass box 24 into the lift chamber 4 through the perforated bottom side 36. The grass box 24 is connected to the cutting chamber 3 by a grass channel 25. Thus, due to the negative pressure (relative to atmospheric pressure) in the grass box 24, air will be drawn into the grass box from the cutting chamber through the grass channel 25 with the grass drawn.

It should be noted that the grass channel 25 provides a path for grass from the blades 6 to the grass box 24; as can be seen in fig. 3, there is a straight path 26 in the area shown in that figure. This means that cut grass is less likely to adhere to the sides of the cutting chamber 3 or grass channel 25 because it does not have any corners to negotiate. Furthermore, because the grass is lifted off the blades 6 by suction from the grass box 24, there is no need to shape the blades for throwing the grass in a particular direction or for generating any air flow; a simple straight edge blade can be used.

As shown in figure 9 of the drawings, there is provided an aperture 26 in the housing which allows air to enter into the cutting chamber 3. This will release the negative pressure (relative to atmospheric pressure) that will build up in the cutting chamber 3 due to the suction of air into the grass box 24. Without such an aperture 26, the negative pressure would tend to draw the housing surrounding the cutting chamber 3 down towards the ground, tending to tilt the mower towards its front and make it inflexible to manoeuvre.

To avoid objects protruding from the bore 26 through the blade, a part-cylindrical wall 27 is provided which is coaxial with the blade 6 but of slightly larger radius and surrounds the blade to block any straight path from the blade to the bore. Because the part-cylindrical wall presents a smooth surface for cut grass or the like, there may be little accumulation of cut grass on this surface. Air will follow a curved path 28 into the cutting chamber 3 before the cut grass is drawn from the blades and along the path 26 into the grass box 24.

As described above, the handle 5 is supported by the housing 1. The handle 5 is connected at a lower end to the housing 1 to pivot about a horizontal axis 34. The upper portion 30 of the handle 5 carries a control 31 of the mower, such as an on/off switch. The handle 5 is generally U-shaped, the user grasping the bar of the U adjacent to the control member 31, and each end of the U is coupled to the housing.

The handle 5 is mounted on the housing 1 by means of an elastic coupling (such as a torsion spring) 32. The resilient coupling 32 allows the handle 5 to rotate relative to the housing 24 about a horizontal axis 34, while tending to bias the handle 5 relative to the housing 1 such that the handle 5 tends to tilt the housing 1 backwards in the direction of arrow 35. Since the lift chamber 4 is located at the rear of the housing, the combined effect tends to counteract the tendency of the mower to tilt forward and tends to balance the weight of the handle 5 for the user. Thus, the lawn mower is more stable and the user feels more comfortable.

Claims

1. A suspended mower comprising: a housing open at a bottom surface thereof and defining a closed cutting chamber and a separate closed lifting chamber on the bottom surface; a cutting element located in the cutting chamber; and a lifting force generating member located in the lifting chamber; wherein the cutting element and the lifting force generating member are mounted for rotation about a substantially vertical axis substantially perpendicular to the bottom surface;

wherein the cutting element is mounted on a cantilevered member that is secured to the housing at a mounting point remote from the cutting element; the bending of at least one of the housing and the cantilevered member allows the cutting element to move relative to the housing generally along a vertical axis of the cutting element.

2. The mower of claim 1 wherein the lift generating member comprises an impeller.

3. The mower of claim 1 or claim 2 including a motor and a lift transmission, the motor having an output shaft, the lift transmission having an input rotatable about a first lift transmission axis and an output rotatable about a second lift transmission axis, the first and second lift transmission axes being spaced apart from one another, the input being coupled to the output to transmit rotation of the input to rotate the output, the input being coupled to the output shaft of the motor and the output being coupled to the lift force generating member.

4. The mower of claim 3 including a cutting transmission having an input rotatable about a first cutting transmission axis and an output rotatable about a second cutting transmission axis, the first and second cutting transmission axes being spaced apart from one another, the input rotatable about the first cutting transmission axis being coupled to the output rotatable about the second cutting transmission axis to transmit rotation of the input rotatable about the first cutting transmission axis to rotate the output rotatable about the second cutting transmission axis, the input rotatable about the first cutting transmission axis being coupled to the output shaft of the motor and the output rotatable about the second cutting transmission axis being coupled to the cutting element.

5. The mower of claim 4 wherein the first cutting drive axis and the first lift drive axis are coincident with the output shaft of the motor, the second cutting drive axis is coincident with the vertical axis of the cutting element, and the second lift drive axis is coincident with the vertical axis of the lift force generating member.

6. The lawnmower of claim 3, wherein the motor is disposed closer to a center of an extending direction of the housing than an edge of the extending direction of the housing in a horizontal plane.

7. A lawnmower as claimed in claim 3 comprising a grass box for collecting cut grass, the motor not being surrounded by any part of the grass box.

8. The mower of claim 4 including an adjuster that drives bending of at least one of the cantilevered member and the housing to move the cutting element.

9. The lawnmower of claim 8, wherein the adjuster is manipulable by a user with the bottom surface lowermost.

10. A lawnmower as claimed in claim 8 or claim 9, the adjuster comprising a crank bar having a crank portion that operates in a slot in the cantilevered member, rotation of the crank bar causing movement of the cantilevered member relative to the housing.

11. A lawnmower as claimed in any one of claims 8 to 9 wherein the cantilever member supports the motor.

12. The mower of claim 11 wherein the cantilevered member supports the lifting transmission and the cutting transmission.

13. A lawnmower as claimed in claim 1 or claim 2 wherein the cutting chamber is provided with a source of suction so that cut grass can exit the cutting element.

14. The mower of claim 13 comprising a path for directing cut grass from the cutting element toward the suction source and a grass box at the end of the path distal from the cutting element, the path being straight.

15. A lawnmower as claimed in claim 14 arranged such that air can be drawn from the cutting chamber into the lifting chamber via the grass box.

16. The lawnmower of claim 13, wherein at least one aperture is provided in the housing surrounding the cutting chamber to allow airflow into the cutting chamber.

17. A lawnmower as claimed in claim 16 wherein the or each aperture is located above the cutting element.

18. A lawnmower as claimed in claim 16 or claim 17 wherein a wall is provided in the cutting chamber between the or each aperture and the cutting element.

19. A lawnmower as claimed in claim 18 wherein the wall physically separates the cutting element from the or each aperture but allows airflow from the or each aperture through the cutting element, the wall defining a bend in the path of air between the or each aperture and the cutting element.

20. The mower of claim 18 wherein the wall is in the form of a portion of a surface of a cylinder.

21. A lawnmower as claimed in claim 1 or claim 2 comprising a handle comprising a portion arranged to be grasped by a user, the handle being mounted on the housing by a resilient coupling which tends to bias the housing with the lowermost floor to lift the cutting chamber.

22. The lawnmower of claim 21, wherein with the bottom surface lowermost, the handle is pivotable about the resilient coupling relative to the housing about a horizontal axis, the handle having only a single degree of rotational freedom relative to the housing.

23. The lawnmower of claim 21, wherein with the cutting chamber at a front of the housing and the lifting chamber at a rear of the housing, the resilient coupling will tend to tilt the front of the housing upward.

24. The mower of claim 2 wherein the impeller is a mixed flow fan.

25. The lawnmower of claim 20, wherein the wall is coaxial with the cutting element.

26. A lawn mower, comprising: a housing opened at a bottom surface thereof and defining a cutting chamber; a cutting element in the cutting chamber, the cutting element mounted for rotation about a substantially vertical axis; and a cantilevered member on which the cutting element is mounted; the cantilevered member is secured to the housing at a mounting point distal from the cutting element; the bending of at least one of the housing and the cantilevered member allows the cutting element to move relative to the housing generally along a vertical axis of the cutting element.

27. The lawnmower of claim 26, comprising an adjuster that drives bending of at least one of the cantilevered member and the housing to move the cutting element.

28. The lawnmower of claim 27, wherein the adjuster is manipulated by a user with the bottom surface lowermost.

29. A lawnmower as claimed in claim 27 or claim 28 wherein the adjuster comprises a crank bar having a crank portion that operates in a slot in the cantilevered member, rotation of the crank bar causing movement of the cantilevered member relative to the housing.

30. The lawnmower of claim 29, wherein the adjuster comprises a locking mechanism whereby the position of the cantilevered member is fixable relative to the housing to thereby fix the position of the cutting element relative to the housing along the vertical axis of the cutting element.

31. The mower of claim 30 wherein the locking mechanism comprises a lever secured to the crank bar, the lever biased against the housing, the adjuster having a plurality of discrete positions, the adjuster locking the position of the cutting element at the discrete positions along a vertical axis of the cutting element; the discrete positions are defined by locators in the housing.

32. A lawnmower as claimed in any one of claims 26 to 28 wherein the cantilever member supports a motor of the lawnmower.

33. The mower of claim 32 including a cutting transmission having an input rotatable about a first cutting transmission axis and an output rotatable about a second cutting transmission axis, the first and second cutting transmission axes being spaced apart from one another, the input coupled to the output to transmit rotation of the input to rotate the output, the input coupled to an output shaft of the motor and the output coupled to the cutting element, the cutting transmission also supported by the cantilevered member.

34. A lawn mower, comprising: a housing opened at a bottom surface thereof and defining a cutting chamber and a lifting chamber on the bottom surface; a cutting element located in the cutting chamber; a lifting force generating device arranged to generate a lifting force in the lifting chamber, the housing surrounding the cutting chamber having at least one aperture provided therein to allow airflow into the cutting chamber; and a wall located in the cutting chamber between the or each aperture and the cutting element.

35. A lawnmower as claimed in claim 34 wherein the or each aperture is located above the cutting element.

36. A lawnmower as claimed in claim 34 wherein the wall physically separates the cutting element from the or each aperture but allows airflow from the or each aperture through the cutting element, the wall defining a bend in the path of air between the or each aperture and the cutting element.

37. A lawnmower as claimed in claim 34 or claim 36 wherein the wall is in the form of part of a cylindrical surface.

38. A lawn mower, comprising: a housing opened at a bottom surface thereof and defining a cutting chamber thereon; a cutting element located in the cutting chamber; and a handle comprising a portion arranged to be grasped by a user, the handle and the housing being connected together by a resilient coupling which, through the lowermost said floor, tends to bias the housing to lift the cutting chamber.

39. The lawnmower of claim 38, wherein the handle is pivotable relative to the housing about the resilient coupling.

40. A lawnmower as claimed in claim 39 wherein the handle is pivotable about the resilient coupling relative to the housing about a horizontal axis by the lowermost floor.

41. The lawnmower of claim 40, wherein the handle has only a single degree of rotational freedom relative to the housing.

42. The mower of claim 40 or claim 41 wherein the resilient coupling applies a biasing torque about the horizontal axis.

43. A lawnmower as claimed in any one of claims 38 to 41 wherein the resilient coupling comprises a torsion spring.

44. A lawnmower as claimed in any one of claims 38 to 41 wherein the housing is provided with a lift chamber on a bottom surface, the lawnmower comprising lift generating means arranged to generate a lift force in the lift chamber.

45. The mower of claim 44 wherein the cutting chamber is located at a front of the housing and the lifting chamber is located at a rear of the housing, the resilient coupling tending to tilt the front of the housing upward.