GB2248758A - Herbicide spreader - Google Patents

Abstract

A spreader for granular herbicide comprises a hopper and herbicide transport assembly (2) for close-mounting behind an agricultural tractor (1). Flexible conduits (7) deliver herbicide from the transport assembly (2) to an array of distribution heads (8), mounted on a roller unit (3) that is pulled behind the tractor. A two-way valve is operative to deliver the herbicide to one or other, but not both at the same time, of the two laterally outermost distribution heads (8), so that the resulting distribution pattern of herbicide is an even spread of substantially the same width as the roller unit, but offset to the right or left of the roller unit so as to fall over previously rolled ground. <IMAGE>

Description

TITLE: Herbicide Spreader DESCRIPTION: Field of the Invention The invention relates to herbicide spreaders for the efficient application of granular herbicides.

Background Agricultural herbicides are generally applied to the ground at seed-sowing time, before the emergence of the sown seed. By killing off all the weeds which germinate on the initial preparation of the seed bed, but before the germination of the sown seed, the sown seed has a much stronger start in life. The most common method of herbicide application is by spraying the herbicide in liquid form, but there are a number of factors which make this method of application undesirable. Principally, there is the environmental problem of spray drift, with the possibility of defoliating hedges or crops in adjacent fields. Some herbicide sprays are effective only when sprayed immediately before rain. Others may be rendered ineffective, or less efficacious, by rain shortly after application.

Herbicides have, for a number of years, been available in solid granular form which avoids the environmental problems discussed above.

For example, Monsanto PLC market a solid granular herbicide under the Trademark AVADEX which can be spread from a wheeled applicator pulled by a low ground effect vehicle. The herbicide must be spread on to a fine firm-rolled seed bed soon after sowing and, therefore, prior to germination, the bed being such that the granules remain on the surface.

When it rains after application, the granules dissolve and form a ground cover film which kills all emergent weeds. Because the herbicide is applied in granular form, it is not as dependent on the weather as is a comparable herbicide in liquid form. The granules may remain on the surface for an extended period before the onset of rain initiates the formation of the ground cover film; or, alternatively, they may be applied during rain, without damaging their herbicidal effectiveness.

The need for a fine firm-rolled seed bed on to which the granular herbicide must be spread is one of the most serious disadvantages of using herbicides in solid granular form. After rolling, any passage over the land by a tractor would break up the surface, at least in the tracks of the tractor tyres, and the result would be the trace of tractor tracks left in uncontrolled weeds where the herbicide had failed to dissolve into a uniform film over the land. Furthermore, an additional passage over the land by a tractor might add to the land compaction, which is known to be undesirable. Those issues have given rise to the recommendation that the granular herbicide spreaders be towed behind low ground effect vehicles, so that there is minimum ground disturbance during spreading of the herbicide.Suitable low ground effect vehicles are the three-wheel and four-wheel All Terrain Vehicles (ATVs) which are currently popular, and each such vehicle is capable of pulling a wheeled herbicide spreader of width four metres without disturbing the surface of a rolled seed bed. Application is, however, slow and, therefore, expensive in terms of man-hours.

There remains, therefore, a need for an alternative and preferably more efficient spreader for granular herbicides.

Summary of the Invention The invention provides a spreader for granular herbicides, comprising a hopper assembly and herbicide transport mechanism for mounting on a three-point linkage of an agricultural tractor, for transporting the granular herbicide to an array of distribution heads mounted on a roller unit that is to be towed behind the tractor, and a two-way valve for directing the herbicide to one or other, but not both at the same time, of the two laterally outermost distribution heads in the array, so that the resulting distribution pattern of herbicide is an even spread of substantially the same width as the roller unit, but offset to the right or left of the roller unit depending on the position of the two-way valve.

Using the spreader of the invention, the seed bed can be rolled and the herbicide applied in a single operation. Moreover, there are no missed patches or areas of overlap or double application, such as there might be using an ATV to pull a wheeled applicator. The very point of using an ATV has been to leave no visible imprint, so that there is little or no visible guide to enable the operator to avoid missed patches and overlap areas. On the contrary, the spreader of the invention leaves a very visible imprint in the form of the roller track imprint, and this is very easy indeed to follow when traversing a parallel path.

The use of the two-way valve gives an asymmetric distribution pattern which is of substantially the same width as the roller, but offset to the right or to the left of the roller according to the position of the two-way valve. The operator controls the valve, so as to direct that offset on the side of previously rolled ground, so that there is little or no tendency to apply the herbicide to ground which is still to be rolled.

Preferably, the hopper and herbicide transport mechanism are mounted on a frame for close coupling to the rear of the tractor. The mechanism for transporting the herbicide down the flexible conduits preferably comprises a fan unit for entraining the granules, of herbicide in an air current. The fan unit may, in use, be powered by a drive belt from a take-off shaft of the tractor.

Preferably, a ground-engaging wheel or spoked hub is mounted on the same mounting as the hopper and herbicide transport mechanism, for varying the delivery rate of the herbicide to the transport mechanism as a function of the rate of travel over the ground. It is important that the wheel or spoked hub should not be fouled and damaged by the drawbar of the roller when the tractor is turning about and, preferably, it can be lifted hydraulically out of the path of engagement with the drawbar, under operator control, prior to turning about. In addition, the wheel or spoked hub may, if desired, be mounted on a swing arm that is pivotable about a vertical axis, so that, if the operator turns without effecting lifting of the wheel or spoked hub, the swing arm merely folds at the pivot and breaks away when fouled by the drawbar, thus avoiding damage.

Preferably, the frame mounting the hopper and herbicide transport mechanism is arranged for ease of removal from the tractor, and preferably the distribution heads and associated flexible conduits are equally easily removable from the roller. The roller can then be used with or without the herbicide spreader in place, and yet the whole can easily and rapidly be assembled on the farm prior to driving the roller to the field.

The roller may be a single or multiple-ganged roller. The spreader of the invention can easily be designed not to interfere with the folding mechanism associated with the road-transport mode of a three-ganged roller.

Drawings Figure 1 is a schematic side view of a tractor towing a ganged roller and provided with a spreader according to the invention; Figure 2 is a perspective view, also schematic, of the basic frame for mounting the hopper assembly and herbicide transport mechanism; Figure 3 is a schematic plan view of a rear frame for mounting the distribution heads over a three-ganged roller, shown in broken lines; Figure 4 is a schematic view from the tractor cab of the hopper assembly and herbicide transport mechanism of Figure 1, mounted on the frame of Figure 2; Figure 5 is a schematic plan view of an improved spreader according to the invention pulled by a tractor; and Figure 6 is a schematic plan view of the same spreader in the next subsequent pass of the tractor, with the position of the two-way valve reversed.

Referring first to Figure 1, a tractor (1) carries a hopper and herbicide transport assembly (2) on its three-point linkage, and tows a three-ganged roller unit (3) through its drawbar. The upper and lower links of the tractor's three-point linkage are indicated as (4) and (5) respectively, but the drawbar is not shown.

Four flexible conduits (7) are detachably mounted on the rear frame (6) cf the roller (3) and terminate in distribution heads (8) for distribution of the granular herbicide blown down the conduits by a current of air from the hopper and transport assembly (2). Each distribution head (8) comprises a nozzle for directing the herbicide against an inclined plate, the distance between the nozzle and the plate being variable to vary the distribution pattern of the herbicide in use. The nozzle/plate distances are set in use so that the five distribution heads (8) arranged across the rear of the roller provide a uniform distribution pattern across substantially the exact width of the roller (3).

Also shown in Figure 1 is a spider wheel (9) on a pivoted arm (10) which can be raised hydraulically to above the level of the drawbar in the direction of arrow 'A'. The spider wheel (9) contacts the ground in use and its rate of rotation is used to control the rate of delivery of herbicide from the hopper assembly to establish a regulated rate of application.

It is important that the hopper assembly and herbicide transport mechanism be close coupled to the tractor, to reduce as far as possible the overhang over the drawbar of the roller unit. Figure 2 shows how this may be achieved, with mounting points (11) for the lower links (5) of the tractor's three-point linkage, being offset rearwardly relative to the support frame (12), and a mounting point (13) for the upper link (4).

Figure 3 illustrates the rear frame (6) of the three-ganged roller unit (3). This rear frame (6) preferably has channel section members (21) pinned and bolted to it for transportation of the five flexible conduits (7) from the hopper assembly (2) down to the distribution heads (8), thus giving ease of removal. Ganged rollers are foldable for road transport, with the outer rollers being raised along the axes 'B' shown in chain-dotted lines.

Figure 4 illustrates the hopper assembly, which comprises two hoppers (14) and (15), and the herbicide transport mechanism (16). The transport mechanism (16) comprises a fan (17) driven by a belt drive contained in a belt-drive housing (18) and powered by a take-off shaft (19) from the tractor (1). Herbicide dispensed from the hoppers (14) and (15), at a rate demanded by the spider wheel (9) is entrained in a cyclone stream of air and transported down the flexible conduits (7) to the distribution heads (8).

As already explained, the spider wheel (9), which is directly connected to the herbicide transport mechanism (16) preferably via an additional frame (22), can be raised by hydraulics (23) to clear the drawbar of the roller unit (3), for turning the tractor at the end of each pass. A valuable safety feature is the provision of a pivot at (20), allowing the arm (10) to break away to the left as viewed in Figure 4 if fouled by the drawbar, but permitting spring return to the correctly aligned position on re-establishment of straight forward movement.

Figures 5 and 6 illustrate the use of the two-way valve. The tractor (1) is pulling a three-ganged roller (3) on which is mounted a herbicide spreader according to Figures 1 to 4. There are five distribution heads (8) and (8') incorporated into the spreader, the heads (8') on the extreme right and extreme left of the array being controlled by a two-way valve (not shown) in the tractor cab. Figure 5 shows how the head (8') of the left-hand side of the tractor (1) is closed when the previously rolled ground is to the right, giving an asymmetric distribution pattern (24) which is offset to the right. Figure 6 shows how, in the next pass, the position of the two-way valve is reversed, so that the distribution pattern (24) is again offset in the direction of the previously rolled ground. In this way, the wastage of herbicide applied to unrolled ground is reduced to a minimum.

Claims (7)

ClAIMS:

1. A spreader for granular herbicides, comprising a hopper assembly and herbicide transport mechanism for mounting on a three-point linkage of an agricultural tractor, for transporting the granular herbicide to an array of distribution heads mounted on a roller unit that is to be towed behind the tractor, and a two-way valve for directing the herbicide to one or other, but not both at the same time, of the two laterally outermost distribution heads in the array, so that the resulting distribution pattern of herbicide is an even spread of substantially the same width as the roller unit, but offset to the right or left of the roller unit depending on the position of the two-way valve.

2. A herbicide spreader as claimed in Claim 1, wherein the roller is a three-ganged roller and there are five distribution heads in the array.

3. A herbicide spreader as claimed in either preceding claim, wherein the hopper and herbicide transport mechanism are mounted on a frame for close coupling to the rear of the tractor.

4. A herbicide spreader as claimed in any preceding claim, wherein the herbicide transport mechanism comprises a fan unit for entraining the granules of herbicide in an air current.

5. A herbicide spreader as claimed in Claim 4, wherein the fan unit is powered by a drive belt from a take-off shaft of the tractor.

6. A herbicide spreader as claimed in any preceding claim, further comprising a ground-engaging wheel or spoked hub, mounted on the same mounting as the hopper and herbicide transport mechanism, for varying the delivery rate of the herbicide to the transport mechanism as a function of the rate of travel over the ground.

7. A spreader for granular herbicides, substantially as described herein with reference to the drawings.