GB2553182A

GB2553182A - Rotary mower

Info

Publication number: GB2553182A
Application number: GB1708244.7A
Authority: GB
Inventors: Cooper Christopher
Original assignee: Hayter Ltd
Current assignee: Hayter Ltd
Priority date: 2016-05-23
Filing date: 2017-05-23
Publication date: 2018-02-28
Anticipated expiration: 2037-05-23
Also published as: GB201708244D0; GB201608992D0; GB2553182B

Abstract

A rotary mower 10 having a cutter blade which, in use, is tilted at an angle to the ground which angle varies as the height of the cut is adjusted. There may be a mechanism with a control lever 16 which when actuated simultaneously adjusts the height of cut and the tilt of the blade. The control lever 16 may be a manual lever. The tilt angle variation may be linear with respect to the cutting height. The rotary mower 10 may have a housing 11 which the blade is mounted in, and front wheels 12 and rear roller 13 mounted on the housing 11. A cuttings collector may be detachably mounted to the mower 10.

Description

(54) Title of the Invention: Rotary mower Abstract Title: Rotary Mower (57) A rotary mower 10 having a cutter blade which, in use, is tilted at an angle to the ground which angle varies as the height of the cut is adjusted. There may be a mechanism with a control lever 16 which when actuated simultaneously adjusts the height of cut and the tilt of the blade. The control lever 16 may be a manual lever. The tilt angle variation may be linear with respect to the cutting height. The rotary mower 10 may have a housing 11 which the blade is mounted in, and front wheels 12 and rear roller 13 mounted on the housing 11. A cuttings collector may be detachably mounted to the mower 10.

Grass Height

ROTARY MOWER

Field and Background

The present invention relates to rotary mowers.

Rotary mowers generally comprise a cutter blade which is adapted to be rotated in a generally horizontal plane by an electric motor, or a petrol or diesel engine. The blade is typically accommodated in a chamber in a housing. The chamber is shaped to direct cuttings to a cuttings collector which is detachably mounted on the housing.

The housing is typically supported on four ground engaging wheels or two ground engaging wheels and a ground engaging roller and the height of the cut can be adjusted by raising or lowering the housing relative to the wheels thereby raising or lowering the blade relative to the ground. Various raising and lowering mechanisms are known for raising and lowering the housing relative to the ground so that the blade is at all times parallel to the ground.

A particular issue with parallel plane rotary mowers is this. It is on the one hand unsightly for a mown lawn to exhibit a wash board, that is half-moon shaped swathes of bent cut grass, and on the other hand detrimental to mower efficiency and blade life for the blade to be longer in contact than necessary with the grass during the course of its rotation. Moreover this remaining in contact with the grass stands to reduce the efficiency of the blade in impelling cuttings into the cutting collector. Thus it can become necessary for a gardener to empty the cuttings collector long before it is full. It is also the case that a mower user, observing that grass cuttings are escaping from below the motor housing can find that the cuttings collector is nowhere near full.

The present invention is aimed at improving mower efficiency and at the same time improving the filling of cuttings collectors.

-2We have found that the utilization of the cuttings collector can be increased by tilting the blade so that it is not parallel to the ground. Moreover, we have found that the optimum angle depends on the length of the cuttings. As most home owners who invest in a quality rotary mower tend to cut their lawns on a regular basis we have found that, in practice, the length of the cuttings is roughly related to the height of the blade and consequently the tilt of the blade can be related to the height of the cut.

It is known to provide a tilting mechanism which is separate and distinct from the raising and lowering mechanism, which tilting mechanism can be actuated to tilt the blade independently of the height of the blade to facilitate cutting coarse grass and weeds and to distribute cuttings as mulch when a cuttings collector is not being used. However, these arrangements do not in any way address the technical problem of the present invention.

The present invention provides a rotary mower having a cutter blade which, in use, is tilted at an angle to the ground which angle varies as the height of the cut is adjusted, by employing a raising/lowering device which effects tilt change in the same operation.

According to a feature of the invention, the rotary mower may have a control lever operated raising and lowering mechanism for adjusting the height of the cutter blade, which, when actuated, simultaneously adjusts the height of the cut and the tilt of the blade.

It has been found particularly suitable for the blade to be tilted 0.5° downwards toward the front of the mower, at the lowest cut height. The lowest cut height is typically of the order of 13mm.

As indicated above a manual lever is customary for raising and lowering the housing. Embodiments of the invention incorporate a manual lever also, with an associated linkage, configured to increase the tilt angle as the cutting height is increased.

-3Typically there may be seven cutting height positions, with cutting height varying from 13mm to 60mm and tilt varying simultaneously, and perhaps linearly, from 0.5° to 1.1° downwards towards the front of the mower.

A particular advantage of thus varying the tilt, where the tilt angle is fixed in relation to the mower housing, is that the accompanying increase of mower housing lift toward the rear of the mower allows an increased air flow into the housing below therefrom. This increases the air pressure and flow into the cuttings collector and accordingly the extent to which the cuttings collector can be fully filled before cuttings flying out from beneath the housing indicate a reduction in cuttings collector collection.

Not only, moreover, is the range 0.5° to 1.1° over a Height of Cut (HOC) range of 1.1mm to 60mm adequate to minimize wash, increase mower efficiency as regards both power use and cuttings collection, but it also means that the range of heights of the driver handles is not so great that at either the lower height or the greater the height of the handle is uncomfortable to the user.

-4Description of Particular Embodiments

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:Figure 1 is a schematic side view of one embodiment of a rotary mower in accordance with the present invention in its lowermost position;

Figure 2 is a schematic side view of the rotary mower in Figure 1 in its uppermost position; and

Figure 3 is a graph indicating the performance benefit accruing from the invention.

Shown in Figures 1 and 2 is a rotary mower 10 comprising a housing 11. Within the housing is a motor and a cutter blade (not shown) while mounted thereupon are front wheels 12 and a rear roller 13. Detachably mounted on the housing 11 above the roller 13 is a cuttings collector (not shown).

The cutter blade is mounted in the housing 11 with a tilt of 0.5° downward forward from horizontal.

The front wheels 12 are mounted at points 14a upon plates 14 which in turn are rotatably mounted to the housing 11 at points 14b. The rear roller 13 is mounted upon a plate 15 at point 15a and this is rotatably attached to the housing 11 at point 15b. A manual control lever 16 is rigidly mounted on the plate 15. A link 17 connects the plates 14 and 15, being pivotally attached thereto at points 14c and 15b. A gate (not shown) is mounted on the housing 11 and has seven notches therealong to receive the lever 16, thus anchoring the lever 16 at any one of seven positions.

By the arrangement just described the cutting height and the tilt angle can be adjusted by moving the control lever 16 between the notches.

In a particular embodiment the cutter blade heights and tilts are set out in the Table 1 below:

-5Table 1

HOC#	HOC (mm)	Forward Pitch (°)
1	13	0.5
2	21	0.6
3	29	0.7
4	37	0.8
5	44	0.9
6	52	1.0
7	60	1.1

The table shows that for seven different cutting height configurations the cutting height varies in stages from 13mm to 60mm and the pitch (tilt downwards toward the front of the mower) from 0.5° to 1.1°.

For use with the cuttings collector mounted on the housing 11, the cutting height is set 10 at the maximum appropriate for the first cut using the lever 16, the mower motor is started and mowing commenced. Upon completion of the first cut the lever 16 is moved to a “lower” notch and the next run commenced. When a lot of the grass cuttings fly out from beneath the housing 11, then, with the motor and/or cutter blade preferably stopped, the cuttings collector is removed from the housing, when it may be emptied. It will be appreciated that with longer grass surrounding the front and sides of the housing

11, the cutter blade readily functions to draw air in from the rear of the housing and direct it, laden with cuttings, into the cuttings collector. When the cuttings collector begins to refuse to accept grass cuttings, they will fly out beneath the housing 11 to the rear thereof. With the housing raised more to the rear thereof, as prescribed in this invention, air take up is optimized.

In Figure 3 the vertical (y) axis represents grass height and the horizontal (x) axis, performance. The grey area represents the length and condition of the grass and the dotted line represents cutting/collection performance. The graph demonstrates the improvement of performance as the cut height is increased. The performance is measured by a combination of motor fuel consumption (watts in the case of an electrical

-6motor and petrol in the case of a petrol motor) and length of run before grass escaping the housing indicates either a full cuttings collector or refusal to accept more cuttings therein.

Claims

1. A rotary mower having a cutter blade which, in use, is tilted at an angle to the ground which angle varies as the height of the cut is adjusted.

2. A rotary mower as claimed in claim 1 and having a raising and lowering mechanism for adjusting the height of the cutter blade, with a control lever which, when actuated, simultaneously adjusts the height of the cut and the tilt of the blade.

3. A rotary mower as claimed in claim 1 or claim 2 and wherein the cutter blade is 0.5° downwards toward the front of the mower, at the lowest cut height.

4. A rotary mower as claimed in claim 3 and wherein the lowest cut height is of the order of 13mm.

5. A rotary mower as claimed in any one of the preceding claims and having a manual lever, with an associated linkage, configured to increase the tilt angle as the cutting height is increased.

6. A rotary mower as claimed in any one of the preceding claims and incorporating seven cutting height positions, with cutting height varying from 13mm to 60mm and tilt varying simultaneously, from 0.5° to 1.1°.

7. A rotary mower as claimed in any one of the preceding claims and wherein the tilt variation is linear with respect to cutting height.

8. A rotary mower as claimed in any one of the preceding claims and having a housing within which is mounted the cutter blade and upon which are mounted front wheels and a rear roller.

9. A rotary mower as claimed in any one of the preceding claims and to which is detachably mounted a cuttings collector.