GB2338637A

GB2338637A - Mowing blade

Info

Publication number: GB2338637A
Application number: GB9914749A
Authority: GB
Inventors: Ernest George Newell
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-06-25
Filing date: 1999-06-24
Publication date: 1999-12-29
Also published as: GB9813630D0; GB2338637A8; GB9914749D0

Abstract

A mowing blade particularly suitable to rotary mowers has a blade rotatable about a vertical axis A. The blade is formed with a planar plate 10 whose outer periphery is of polygonal shape. The corners of the polygon 11 are turned up or down out of the plane of the plate and the angle may be in a range of 0‹ to 45‹ to the plane. In one arrangement (figs 5 and 6) the side edges of the plate are turned up or down throughout their length. The plate may be square or triangular (figs 3 and 4) in plan view.

Description

2338637 1 MOWING BLADE This invention relates to mowing blades

particularly for mowers known as rotary mowers having a blade or blades rotatable about a vertical axis or axes.

Conventionally rotary mowers have blades mounted at the ends of arms and rotatable about a central vertical axis.

An object of the invention is to provide an improved mower blade for rotary mowers.

According to the invention a mowing blade for mowers comprises a planar plate whose outer periphery is of polygonal shape, the corners of the polygon being turned up or down out of the plane of the plate, the blade having a central fixing for securing the blade for rotation 10 about its central axis, the axis of rotation lying transverse to the plane of the plate.

Preferably the corners are turned up or down at an angle of between 0' and 45' to the plane of the plate.

Conveniently the plate is formed of metal suited to the duties of the blade.

The blade may find particular application to rotary mowers having a blade rotatable about 15 a vertical axis, including mowers providing an air cushion on which the mower is supported. However the blade may be used with other rotary mowers mounted on wheels or rollers.

The blade may be used in conjunction with other similar blades set across the width of a mower and having common drive means.

Conveniently the blade is of triangular shape having three corners but the blade may also be 20 of square shape with four corners, or even of five or more sided shapes.

2 The blade may be used on an air cushion mower and on wheeled or roller mounted rotary mowers. The blade may have the corners directed upwardly from the plane of the plate or the corners may be turned downwardly towards the ground with each kind of mower.

Further features of the invention will appear from the following description of embodiments 5 of the invention given by way of example only and with reference to the drawings, in which:

Fig 1 is a plan view of a mower blade according to one embodiment of the invention, Fig 2 is a cross-section on the line 2-2 in Fig 1, Fig 3 is a plan view of another embodiment of mower blade, Fig 4 is a section on the line 4-4 in Fig 3, Fig 5 is a plan view of another embodiment of mower blade, and Fig 6 is a section on the line 6-6 in Fig 5.

Referring to the drawings and firstly to Figs 1 and 2 there is shown a mower blade for use in a rotary mower and arranged for rotation about a substantially vertical axis A. The mower blade 10 is in the form of a square plate which is generally planar and has the four corners of the square upturned as at 11 at an angle of between 0' and 45% preferably at 10' to 40' to the plane of the plate which is in the same plane to the surface being mown. The plate 10 is formed of metal sheet in which there is formed a central opening 12 by which the blade is attachable to the mower and the portions 11 are bent over from the plane sheet. The sheet is formed of material suited to the duty of the blade and may be of plastics, spring steel or 20 mild steel.

In rotation of the blade 10 in the direction R as shown in Fig 1 the blade effects a cutting action along the leading edges of the blade which are those parts of the edges marked C in 3 Fig 1, cutting therefore taking place over the leading edges of the upturned portions 11 and over part of the planar surface of the blade adjacent its edge, ie from the centre point of the edge to the outer point of each edge.

The blade 10 is attachable to the vertical drive shaft 15 of the mower and is secured to said 5 shaft 15 by fixing means 16 which may be of any convenient kind which enables the blade 10 to be replaced when wear takes place.

As shown in Figs 1 and 2 the upturned portions 11 extend upwardly out of the plane 10 but the blade 10 may be secured in a position inverted compared with that shown so that the portions 11 are then directed downwardly from the plane of the blade 10, the portions 11 then providing the cutting edges of the blade 10.

The position of the blade 10, as shown in Figs 1 and 2, may be more suitable for air cushion supported mowers so that the lower surface of the blade 10 may act in some respect to support the mower in relation to the ground. For other rotary mowers in which the mower is supported on wheels and/or rollers the blade 10 may be in the inverted position, as described. However the blade 10 in the position shown in the drawings or in the inverted position may be used in both kinds of mower.

The mower will usually be provided with a shroud or shield 18 which surrounds the blade 10 to prevent inadvertent contact with the blade by the user.

Referring now to Figs 3 and 4 there is shown a blade 20 which, in this case, is of generally triangular shape, each of the points of the triangle having an upturned portion 2 1. In other respects the blade 20 is similar to the blade 10 as described in relation to Figs 1 and 2.

Referring now to Figs 5 and 6 there is shown another blade 30 of generally triangular shape in plan view which is rotatable about an upright axis A and in this case the edges of each side of the triangle are upturned as at 31 to extend from corner to corner of the triangle.

4 The blade 30 rotates about the axis A in a direction R in which case the cutting edges are at C, or in the reverse direction. The edges are upturned at 31 at an angle of 0-45', preferably 10-40', to the horizontal and the outer edges of the upturned portions constitute the cutting edges. Alternatively the blade is mounted inverted so that the edges 31 are down turned. It will be appreciated that in this arrangement the blade is also upturned at the corners of the triangle.

The cutting blades of the invention may be mounted to be resiliently vertically moveable to accommodate undulations and irregularities in the ground surface over which they travel. For example the mounting for the blade may be on an arm which can move up and down to 10 adjust the depth of cut and/or to accommodate changes in the ground contours.

Instead of the fixing arrangement shown the centre of the blade 10 or 20 may be provided with an upwardly convex depression on its upper surface so that fixing elements do not protrude beyond the lower surface of the blade.

The mower blade of the invention may be employed on all kinds of rotary mowing machines and also on machines used by farmers to cut standing crops. In the latter case there may be provided the cutting blade of the invention located across the width of a mowing machine and arranged to effect cutting across the full width of the machine. This may be either by closely spacing the blades, synchronising the speeds so that the blades overlap. Alternatively blades may be spaced apart and further blades may be located in the spacings between the first set of blades. Generally the blades will be driven from common drive means by any suitable drive arrangement.

A spacer may be fitted to the underside of the blade 10 in the form, for example, of a disc of the desired thickness whether the blade is located with upturned or downtumed corners. Particularly in the latter case the spacer provides a limit on the closeness of the blade to the ground. Such a spacer is shown at 25 in Fig 4.

The mower blade of the invention has been found to effect cutting efficiently even over uneven surfaces and discontinuities.

6

Claims

1. A mowing blade for mowers which comprises a planar plate whose outer periphery is of polygonal shape, the corners of the polygon being turned up or down out of the plane of the plate, the blade having a central fixing for securing the blade for rotation about its central axis, the axis of rotation lying transverse to the plane of the plate.

A mowing blade according to claim 1 in which the corners are turned up or down at an angle of between 0' and 45' to the plane of the plate.

A mowing blade according to claim 1 or 2 wherein the corners are turned up or down at an angle of between 10' and 40' to the plane of the plate.

4. A mowing blade wherein the plate is of generally triangular shape in plan view having three corners.

5.

A mowing blade according to any one of the preceding claims wherein the plane of the plate is turned up or down along the side edges.

6. A mowing blade according to claims 1-3 wherein the plate is of square shape in plan view having four corners each of which are turned up or down out of the plane of the plate.

7 A mowing blade according to any one of the preceding claims in which the blade is locatable in use with the corners turned up or in the inverted position with the corners turned down out of the plane of the plate.

8. A mowing blade according to any one of the preceding claims wherein the blade is formed of metal.

7 9.

A mowing blade according to any one of the preceding claims wherein the plate is arranged for vertical movement relative to the ground surface to be mown.

10. A mowing blade for rotary mowers substantially as described with reference to Figs 1 and 2, 3 and 4 or Figs 5 and 6 of the drawings.