GB2037558A - Rotary grass mowing machines - Google Patents

Abstract

A rotary grass mowing machine comprises a casing (3) providing a chamber (11) with a downwardly facing inlet (13) and a lateral passage (15) extending from the chamber, and having a blade (5) disposed within the chamber and rotatable so as to sweep a plane disposed generally parallel to the ground (8). In order to avoid danger from stones discharged with cuttings through the passage, an upright deflector (31) suitably made of plastic or a hinged metal sheet, is mounted within and extends across the passage in a lower part thereof. The defector is spaced a substantial distance from the plane swept by the blade so that stones struck during rotation of the blade are projected against the deflector and fall to ground whilst cuttings entrained in the air flow are discharged through the passage above the deflector. A baffle (27) may also be provided to prevent stones passing above the deflector. <IMAGE>

Description

SPECIFICATION Rotary grass mowing machines This invention relates to rotary grass mowing machines and particularly to rotary grass mowing machines comprising a casing, having a top and a depending skirt which together provide a chamber with a downwardly facing inlet and a lateral passage extending from the chamber for discharge of cuttings, a rotatable blade disposed within the chamber of the casing and a driving shaft extending through the top of the casing and on which the blade is mounted so as to sweep a plane which in operation is disposed generally parallel to the ground and to cause a flow of air through the inlet transversely with respect to said plane.Machines of the kind set forth may be provided with more than one rotatable blade within the casing and may also be provided in the form of a pedestrian controlled machine, or as a ride-on machine which is adapted to be mounted on a self-propelled vehicle, when a number of mowing machines may be arranged to afford an increased width of swath. With the ride-on type of machine, the rotary grass mowing machine may be one of a number of alternative pieces of equipment for use with a basic tractor unit. Alternatively, the basic tractor unit may be fitted up with one or more rotary heads as a specialised machine for grass cutting only.

Inherent in many machines of the above kind is the danger of stones or other heavy objects hit by the blade being projected at high speed through the lateral passage. A variety of ways of reducing this danger have been proposed. For example, in some machines, stones entering the discharge passage with cuttings are directed up to the roof, and they are there given a downward component of momentum and exit from the passage to fall to the ground quite close to the machine so that there is no danger of stones flying upwardly to hit an operator or bystander but a person standing close to the machine is still at risk. Alternatively, a shield of some kind may be provided at the exit of the passage in order to prevent high speed discharge of stones with the cuttings.However, this tends to blockthe exit, and cause clogging of cuttings although it does reduce the danger of discharge of stones.

According to the present invention there is provided an improved rotary grass mowing machine of the kind set forth, wherein the blade is located adjacent the inlet of the chamber and an upright deflector is mounted within and extends across the lateral passage in a lower part thereof and is spaced a substantial distance from the plane swept by the blade so that stones struck during rotation of the blade are projected against the deflector and fall to ground whilst cuttings entrained in the air flow transverse to the blade pass out of the casing through the lateral passage above the deflector.

Preferably, a baffle is mounted within the chamber above the level of the plane swept by the blade and extends inwardly from the deflector towards the axis of rotation of the blade, and advantageously, in plan view of the machine, the inner edge of the baffle is disposed adjacent the periphery of the plane swept by the blade. The deflector can suitably depend from the baffle.

Advantageously, the deflector is adapted to absorb energy from stones impinging thereon. The deflector may be a hingedly mounted plate and suitably comprises plastics material, such as polyurethane.

To reduce the likelihood of stones being projected beneath the deflector, the lower edge of the deflector is preferably located below the level of the inlet of the chamber.

Preferably, the blade, at respective opposite ends, is formed along the trailing edges thereof with upturned portions serving to enhance air flow transversely with respect to the plane swept by the blade.

In one embodiment of the invention, the machine is a pedestrian controlled machine and the lateral passage is tapered from the chamber so as to divert the outflow of cuttings from the passage away from the pedestrian controller. Where the machine is adapted to be mounted on a self-propelled vehicle, the passage may be tapered or, alternatively, the width of the passage may be substantially uniform along its length so as to distribute cuttings over a wider area. The outer end portion of the passage may be inclined upwardly or downwardly from the chamber.

The invention will now be described, by way of example, with reference to the accompanying, somewhat diagrammatic drawings in which: Figure 1 is a plan view of one embodiment of a rotary grass mowing machine according to this invention; Figure 2 is a cross-sectional view taken along the line ll-ll of Figure 1; Figure 3 is a plan view of a second embodiment of the invention; and Figure 4 is a cross sectional view taken along the line IV-IV of Figure 3.

Throughout the drawings like parts are identified by the same reference numerals.

Referring to the drawings, a rotary grass mowing machine, generally indicated by the reference numeral 1, comprises a casing 3, carried on ground engaging wheels 4, in which is disposed a rotatable blade 5. The casing 3 is formed with a flat top 7 and a peripheral depending skirt 9 of substantial depth.

The top 7 and skirt 9 together form a chamber 11 with a downwardly facing inlet 13. A lateral passage 15, for the discharge of cuttings, extends from the chamber 11.

The rotatable blade 5 is disposed within the chamber 11 of the casing, and is mounted on a driv ing shaft 17 which is located in an upright bearing 19 supported at right angles to the top 7 of the casing.

The shaft 17 projects through the top 7 where there is provided a pulley 21 keyed to the shaft and by means of which a belt drive may be provided which is coupled to a driven member on a vehicle on which the machine is mounted. The blade is mounted on the shaft so that, in operation, the belt drive causes the blade to rotate, sweeping a plane generally paral lel to the casing top 7 and during cutting the plane will be parallel, or approximately so, with the ground 8. The rotation ofthe blade causes a flow of air through the inlet 13 transversely with respect to the plane swept by the blade.This axial flow of air is appreciably enhanced by the provision, at respective opposite ends of the blade, along the trailing edges thereof, of upturned portions 23, which are upwardly and rearwardly inclined with respect to the direction of cutting motion of the blade, indicated by an arrow in Figures 1 and 3, and which effectively serve as fan blades. The blade is mounted on the lower end of the shaft 17 at a relatively low level in relation to the depth of the chamber 11, and is located adjacentthe inlet 13 of the chamber. In operation, the blade rotates and grass is cut by cutting edges 25 formed on the leading edges of the blade at respective opposite ends. Stones and other matter may also be hit by the leading edges of the blade and be raised above the level of the plane swept by the blade.

Within the chamber 11 and above the level of the plane swept by the blade 5, there is provided a baffle 27 which extends within the lateral passage 15 and from the skirt 9 inwardly towards the shaft 17 and parallel with the top of the casing. An inner edge 29 of the baffle is concentric with the shaft and the blade axis, and, as shown in Figures 1 and 3, in plan view of the machine inner edge 29 is disposed adjacent the periphery of the plane swept by the blade.

The baffle inhibits the passage of stones, impacted by the blade, through the passage 15.

An upright deflector 31 is mounted within the lateral passage 15 so as to depend by means of a bracket 33 at its upper edge from the baffle 27. The deflector extends across the full width of the passage 15 in a lower part thereof so that stones projected towards the lower part of the passage impinge upon the deflector and are deflected to the ground instead of passing out of the machine with cuttings through exit 35 of the passage. The deflector is spaced a substantial distance from the plane swept by the blade and consequently stones hit by the blade and entering the passage generally acquire, prior to contacting the deflector, a downward component of velocity and fall below the level of the upper part 36 of the passage above the deflector.The deflector extends across the lower part of the passage 15 so asto provide an unimpeded path for cuttings through the upper part 36 of the passage, thereby reducing the risk of clogging. The baffle 27 acts as a safety measure to ensure that few, if any, stones which are projected upwards by the blade pass above the deflector 31. Cuttings, however, are entrained in the air flow transverse to the blade, are lifted above the level of the baffle 27 and pass out of the casing through the upper part 36 of the lateral passage above the deflector 31. Thus stones, which are not so uplifted, are separated from the cuttings and are projected beneath the baffle to the deflector. The stones generally already have a downward component of velocity and so they are deflected towards the ground 8.The deflector is formed of a tough polyurethane sheet which absorbs energy from stones, so that even if stones are moving upwardly when they hit the deflector, they will fall to ground after impact. The deflector may be hingedly supported along its upper edge by the baffle, to assist in absorbing impact of stones. By reason of the fact that the deflector is spaced a sub stantial distance from the sweep of the blade, the stones, after hitting the deflector, do not pass back into the plane swept by the blade so that the probability of stones being hit a second or even a third time by the blade is very smail so that the working life of the blade is extended. Instead, the stones fall from the deflector to the ground 8.The lower edge 37 of the deflector is located below the level of the inlet 13 to reduce the danger of stones passing beneath the deflector and injuring an operator or bystander.

The two embodiments of the invention which are illustrated respectively provide for upward and downward discharge of cuttings. To this end in the embodiment depicted in Figures 1 and 2 an outer end portion of the passage 15 is upwardly inclined from the chamber, and is formed by upright side walls 39 and a bottom part 41 which extends upwardly from the baffle and the upper edge of the deflector to the exit 35 of the passage. The embodiment of Figures 3 and 4 by contrast has an outer end portion of the passage 15 downwardly inclined from the chamber, with upright side walls 43 and a top part 45 which extends downwardly from the top wall 7 of the casing to the exit 35.

In both of the machines illustrated, the passage is provided at the rear of the machine, relative to forward motion thereof. The machines are suitable for pedestrian control and the passage is tapered from the chamber so as to divert the outflow of cuttings from the exit 35 of the passage away from the pedestrian controller. In a pedestrian controlled machine, however, the pulley 21 may be replaced by a motor, and the shaft 17 may be the engine shaft. Where the machine is adapted to be mounted on a selfpropelled vehicle, for example as a ride-on machine on a tractor, the passage may be tapered, as shown, to direct the cuttings in a particular direction or, alternatively, the side walls of the passage may be parallel so that the passage is of uniform width along its length to scatter cuttings over a wider area.

In operation, the blade 5 is rotated at a speed, normally around 3000 r.p.m., which is sufficient to cause a substantial draught of air transverse to the blade. Grass and like cuttings, cut by the cutting edges 25, are lifted well above the level of the plane swept by the blade so that they pass above the baffle and into the upper part 36 of the lateral passage 15 above the top of the deflector 31, to leave the machine through the exit 35 of the passage. In the embodiment illustrated in Figures 1 and 2 the outer end portion of the passage is upwardly inclined and the cuttings are scattered over the ground, whilst in the machine of Figures 3 and 4 the outer end portion of the passage inclines downwardly and cuttings are deposited on the ground.

Stones and other objects which enterthe chamber after impact by the blade are not caught up in the air flow. Some are projected against the skirt 9 of the casing while others are projected towards the lateral passage. Of these, a proportion will hit the baffle and be deflected downwardly but in any case most of the stones will be moving downwards by the time they reach the deflector which is spaced a substantial distance from the plane swept by the blade. On impact, the deflector absorbs energy from the stones, which fall safely to the ground without re-entering the plane swept by the blade. Accordingly, cuttings and stones are separated within the machine so that cuttings leave via passage 15 and exit 35, whilst stones fall back to ground.

Those skilled in the art will appreciate that many changes may be incorporated in the embodiments of the invention described without departing from the scope of the invention. Thus, for example, the drive to the shaft 17 may be a chain drive. The shape of the baffle 27 may differ appreciably from that shown, as may the mode of mounting the deflector within the passage. Also, the form of the passage may be varied although it would normally extend from the rear of the machine relative to forward motion thereof.

Whilst the machine described is mounted on wheels 4, in the case where the machine or several machines are supported on a ride-on vehicle, ground engaging skids could replace the wheels to facilitate floating of machine or machines over the ground contours.

Claims (15)

1. A rotary grass mowing machine comprising a casing, having a top and a depending skirt which together provide a chamber with a downwardly facing inlet and a lateral passage extending from the chamber for discharge of cuttings, a rotatable blade disposed within the chamber of the casing and a driving shaft extending through the top of the casing and on which the blade is mounted so as to sweep a plane which in operation is disposed generally parallel to the ground and to cause a flow of air through the inlet transversely with respect to said plane, wherein the blade is located adjacent the inlet of the chamber and an upright deflector is mounted within and extends across the lateral passage in a lower part thereof and is spaced a substantial distance from the plane swept by the blade so that stones struck during rotation of the blade are projected against the deflector and fall to ground whilst cuttings entrained in the air flow transverse to the blade pass out of the casing through the lateral passage above the deflector.

2. A rotary grass mowing machine as claimed in claim 1, wherein a baffle is mounted within the chamber above the level of the plane swept by the blade and extends inwardly from the deflector towards the axis of rotation of the blade.

3. A rotary grass mowing machine as claimed in claim 2, wherein the inner edge of the baffle in plan view of the machine is disposed adjacent the periphery of the plane swept by the blade.

4. A rotary grass mowing machine as claimed in claim 2 or claim 3, wherein the deflector depends from the baffle.

5. A rotary grass mowing machine as claimed in any preceding claim, wherein the deflector is adapted to absorb energy from stones impinging thereon.

6. A rotary grass mowing machine as claimed in claim 5, wherein the deflector comprises a hingedly mounted plate.

7. A rotary grass mowing machine as claimed in any preceding claim, wherein the deflector comprises plastics material.

8. A rotary grass mowing machine as claimed in any preceding claim, wherein the lower edge of the deflector is located below the level of the inlet of the chamber.

9. A rotary grass mowing machine as claimed in any preceding claim, wherein the blade, at respective opposite ends, is formed along the trailing edges thereof with upturned portions serving to enhance air flow transversely with respect to the plane swept by the blade.

10. A rotary grass mowing machine as claimed in claim 9, wherein the upturned portions of the blade are upwardly and rearwardly inclined with respect to the direction of cutting motion of the blade.

11. A rotary grass mowing machine as claimed in any preceding claim, wherein the machine is pedestrian controlled, and the lateral passage is tapered from the chamber so as to divert the outflow of cuttings from the passage away from the pedestrian controller.

12. A rotary grass mowing machine as claimed in any one of claims 1 to 10, wherein the width of the passage is substantially uniform along its length.

13. A rotary grass mowing machine as claimed in any preceding claim, wherein an outer end portion of the passage inclines upwardly from the chamber.

14. A rotary grass mowing machine as claimed in any one of claims 1 to 12 wherein an outer end portion of the passage inclines downwardly from the chamber.

15. A rotary grass mowing machine constructed and adapted to operate substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.