AU675883B2 - An earthworking implement - Google Patents

Description

"AN EARTH ORKING IMPLEMENT" THIS INVENTION relates to an implement for soil working. In particular, the invention is directed to an agricultural implement for working soil in an energy efficient manner, with minimum disturbance to the soil surface. The soil may be worked for the purpose of tilling, soil loosening, seeding, fertilising or other cultivating purposes, as well as for non-agricultural tasks such as trench f-rming. _ ΛCKGROUND ART

Soil working is a necessary part of crop cultivation. The soil is turned or otherwise worked for the purpose of loosening the soil and thereby facilitating root growth, and/or for the purpose of aerating the soil to add nitrogen and other nutrients. Conventional soil working implements, such as mouldboard ploughs, apply compressive forces to the soil to turn it. Since soil is strong under compression, such soil working operations use considerable energy, thereby imposing higher power requirements on the tractor pulling the implement. Furthermore, such compressive forces tend to compact the soil.

There are recognised benefits in having a layer of mulch on the soil surface. The mulch helps retains moisture in the soil, and prevents erosion. In pastures, the soil is covered by grasses which not only provide feed but also hold the soil surface together. Although it is often desirable to loosen and/or aerate the subsoil, most conventional tillage implements destroy any surface layer or sward, and remove surface cohesion. Conventional implements leave a very loose layer of soil on the ground surface. The loose _ surface layer is susceptible to erosion by wind and rain.

A known soil working implement, referred to as "an opposed disc plough", comprises two spaced-apart dish-shaped upright discs having their convex surfaces outermost. The discs are angled to each other so that they are widely divergent in the direction of travel. In use, the discs are pulled through the soil to lift and turn the soil between the discs and form a ridge of broken earth. Each disc functions, in effect, as a ploughshare and mouldboard. However, the known opposed disc plough suffers from the disadvantages mentioned above. Namely, it uses considerable energy as it applies compressive forces to the soil to move it. It also requires a strong tractive force, particularly in adhesive soils. Further, the surface of the worked soil is broken up substantially and is vulnerable to erosion.

British patent specifications nos. 1493346 and 1574412 describe soil loosening implements having fixed blades drawn edgewise through the ground. The blades are orientated at an acute angle to the vertical, and are profiled to loosen and lift the soil. Although such implements cause less disruption to the soil surface, they require relatively high forces to pull them through the ground, due to frictional resistance between the static earth and the large surfaces of the moving blades. Further, unbalanced lateral forces on the blades may cause the towing vehicle to lose stability and crab. Yet further, the blades are subject to rapid wear in abrasive soils. It is an object of the present invention to provide an earthworking implement which overcomes or ameliorates the abovedescribed disadvantages, or which at least provides the consumer with a useful choice.

SUMMARY OF THE INVENTION In one broad form, the present invention provides an earthworking implement comprising a pair of spaced-apart substantially planar members adapted to be inserted at least partially in the ground and moved generally edgewise therealong, characterised in that each planar member is mounted for rotation about a respective transverse axis, and in that the pair of planar members are orientated so that they are divergent in both the direction of travel and in an upward direction, wherein in use, the section of soil between the planar members is lifted relative to the ground before falling back into a trough formed in the ground by the planar members.

Typically, the planar members are flat circular discs, such as coulters. The discs are suitably mounted on stub axles for rotation about their respective central axis. The peripheral edge portion of each disc may suitably be notched, rippled, fluted or corrugated to assist rotation of the disc as it moves relative to the ground.

Advantageously, the stub axles are adjustably mounted on respective arms. The arms are pivotally mounted and biased to an operating position by springs or other biasing members. In this manner, the discs are resiliently biased to their operation position, but may deflect to track around rocks or other obstacles. In an alternative embodiment, each planar member comprises a central hub having a plurality of radially extending tines or prongs, the ends of which may be angled.

Typically, the earthworking implement is mounted behind a tractor and drawn along the ground. However, smaller versions of the implement may be hand pulled or pushed.

As the planar members are moved through the ground, a wedge of soil between the blades (generally of trapezial or triangular section) is separated from, and lifted relative to, the surrounding ground. The inclined sides of this wedge-like section are cut by the leading edges of the planar members. The bottom edge of this section is defined by the line of tensile failure between the section and the subjacent ground.

The section of soil between the planar members is slightly compressed as it passes between the planar members since the planar members converge rearwardly. As the planar members are divergent in the upward direction, the squeezing of the soil section (coupled with the rotation of the planar members) imparts a tensile force to the soil drawing the section upwardly. This causes the section to separate from the soil by tensile failure. Since soil is generally much weaker in tension than compression, less energy is required to separate the section of soil from the surrounding soil. Tillage energy usage per volume of soil tilled is therefore minimised.

The compressive forces applied to the soil by the planar member are relatively low. Further, the lateral compression forces on the wedge of soil balance each other, leaving a nett upward lifting force on the soil.

As the planar members are free to rotate with travel through the ground, there is little frictional force on the implement.

Moreover, there is minimal disruption of the surface layer of the soil.

The implement can also comprise one or more conduits for delivering seeds, fertiliser, water, etc. into the ground. A conduit may be provided for either or both planar members. The conduit has an opening adjacent the trailing face of its associated planar member, and delivers seeds, fertiliser, water or other materials into the groove formed in the ground by the obliquely angled planar member. The delivered material is therefore inserted between the side of the wedge cut by the planar member and the adjacent ground. In this manner, the implement can function also as a seeder, fertiliser or the like.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described by way of example, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a rear perspective view of an earthworking implement according to one embodiment of the invention;

Fig. 2 is a schematic plan view of the discs of Fig. 1; Fig. 3 is a schematic end elevational view of the discs of Fig. 1;

Fig. 4 is a schematic perspective view illustrating the operation of the implement of Fig. 1;

Fig. 5 is a schematic sectional view illustrating the operation of the implement of Fig. 1; and

Fig. 6 is a schematic perspective view of another embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS As shown in Fig. 1, an earthworking implement

10 comprises a pair of spaced-apart planar members in the form of relatively thin discs 11, 12 (also known as coulters). The discs 11, 12 of the illustrated embodiment are provided with fluted or corrugated peripheral edge portions. However, the discs may be smooth edge coulters, notched coulters, offset fluted coulters, offset rippled coulters, offset bubble coulters or any other suitable type of disc-like component. Each disc 11, 12 is rotatably mounted on a respective stub axle 13, 14 by a suitable bearing arrangement.

Each stub axle 13, 14 has a flange 13A, 14A extending from its housing to enable it to be mounted to a respective support arm 15, 16 via an L-shaped bracket 13B, 14B. The brackets 13B, 14B are adjustably mounted to respective support arms 15, 16. The adjustable mounting along the length of the support arms 15, 16 enables the spacing between the discs 11, 12 to be varied.

The arms 15, 16 of the illustrated embodiment are pivotally mounted to a common pivot pin 17 such that the arms 15, 16 pivot about a common axis generally coplanar with the direction of travel. However, the support arms may alternatively pivot about separate pivot axes.

Lever arms 18, 19 are connected respectively to arms 15, 16 and extend radially from pivot pin 17. Respective coil springs 20, 21 are connected between the ends of lever arms 18, 19 and an adjustable fitting 22 mounted on a central arm 23, as shown in Fig. 1. The central arm 23 is adapted to be mounted to a tool bar 24 at the rear of a tractor or similar vehicle.

The springs 20, 21 bias the bottom edges of the disc 11, 12 towards each other. However, the bottom edges of the discs 11, 12 may be pulled apart against the bias of the springs 20, 21. Thus, in use, the discs may deflect or track around rocks or other obstacles.

The spacing between the bottom edges of the discs 11, 12 can also be varied by the adjustable fitting 22 which varies the angular orientation of the discs 11, 12 relative to the vertical.

A tube 25, or similar conduit, can be located adjacent the trailing face of each disc 11, 12. The bottom opening of the tube 25 is located near the bottom edge of its respective disc, while the upper end of the tube is connected to a supply of material to be delivered into the ground. The function of the tube 25 will be described in more detail later. As can be seen more clearly in Figs. 2 and 3, the discs 11, 12 are orientated so that they are divergent in both the direction of travel, and in the upward direction. (For clarity, the discs 11, 12 are shown schematically as simple discs in these drawings, and details of their mounting and other components of the implement are omitted for clarity).

Referring to the plan view of Fig. 2, it can be seen that the discs are divergent in the direction of travel of the implement during normal operation (illustrated by the arrow). In other words, the trailing edges of the disc 11, 12 are closer together than their leading edges. The divergence of the discs 11, 12 is not great. Typically, the plane of each disc is angled outwardly from the direction of travel by about 14°, although the orientation of the disc can be varied to suit particular applications.

Referring to the end elevational view of Fig. 3, it is apparent that the discs 11, 12 are also divergent in the upward direction. That is, the discs are cambered so that their lower edges are closer together than their upper edges. Typically, the plane of each disc is angled outwardly from the vertical by about 45°, although the orientation may be varied to suit particular applications.

The operation of the implement 10 is illustrated schematically in Figs. 4 and 5. In use, the discs 11, 12 are lowered into the ground to the desired depth. The implement is then pulled in the direction of travel at substantially the same depth by the tractor or other towing vehicle. As the discs 11, 12 move through the soil, they rotate about their respective stub axles, the fluted or corrugated edges of the discs assisting the rotation of the discs. Since the discs rotate, there is relatively litfe friction for the pulling vehicle to overcome.

As the discs 11, 12 move through the soil, they cut a wedge-shaped section 26 which is generally of trapezial shape, or of triangular shape if the discs are closer together. Due to the orientation of the discs, and their rotation, this wedge section 26 is lifted relative to the surrounding soil, causing tensile failure along line 27 as shown in Fig. 5. Since soil is much weaker in tension that compression, far less energy is required to cause the separation of this section of soil from the surrounding ground. The laterally inward forces applied to the wedge section 26 by the discs 11, 12 balance each other, leaving a nett upward force on the section.

After having been separated from, and lifted relative to, the surrounding soil, the wedge section 26 falls back into its associated trench under gravity once the discs 11, 12 have passed by. The separation and lifting of the section helps aerate the soil and loosen the soil.

It is to be noted that the surface layer 28 of the section 26 is minimally affected by the edgewise passage of the discs 11, 12. Thus, any grasses or mulch layer on the surface 28 is relatively undisturbed, and surface cohesion is maintained even though the subsoil has been loosened. The implement 10 of this invention is also suitable for use as a seeder, fertiliser or other device for introducing materials into the subsoil. Such seeds, fertiliser or other materials can be fed through the tubes 25 located behind each disc. As the disc is angled to the direction of travel, it opens up a groove in the soil as it moves along the ground. The outlet of tube 25 is suitably positioned to deliver the seeds, fertiliser or other material into the groove so formed. This groove is automatically closed by the wedge of soil 26 falling back into the channel cut in the soil. The seeds etc. are therefore held between the wedge 26 and the surrounding soil. If desired, a press wheel may be mounted to each flange 13A, 14A to press close the groove formed by the respective disc 11, 12. If the discs are spaced relatively wide apart and/or inserted only a small distance into the ground, e.g. when sowing seed at very shallow depths, the discs may lift two triangular sections of soil, one adjacent the bottom edge of each disc. A plurality of pairs of discs 11, 12 may be mounted behind a tractor as shown in Fig. 5B of Australian provisional application no. PM3115, the disclosure of which is incorporated herein by reference.

The implement 10 may be designed for towing by a tractor or the like, or for manual operation. The discs 11, 12 are dimensioned to suit the particular application. For example, the discs may vary from 150mm diameter, 2mm thickness discs for a hand-operated garden tool, to 1500mm diameter, 20mm thickness discs for a tractor mounted implement.

The implement 10 can be used for lawn or turf maintenance, e.g. to loosen an existing sward. The implement 10 may also be used for non- agricultural tasks, such as trench digging. Once the discs have passed through the ground, the cut section 26 can be removed easily to leave a trench. The removal of the cut section 26 can be mechanised by mounting a suitably shaped fitting to the rear of the implement to lift the section 26 out of the trench. The implement may also be used to assist removal of a cable from the ground by passing the discs along opposite sides of the cable to loosen the soil surrounding the cable. Other applications of the implement will be apparent to those skilled in the art.

In the embodiment of Fig. 6, the solid discs 11, 12 are replaced by spoked wheels 30 each comprising a hub 31 and a plurality of radially extending tynes 32. The tynes may have hooked shaped ends 33 to assist operation of the implement.

The foregoing describes only some embodiments of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention. For example, a slender bearing housing may be mounted on the outside of each disc to mount the disc to its respective arm. This leaves the soil flow path between the discs essentially unobstructed (by the stub axle housings or other components) . Each bearing housing travels in the slot or groove cut in the ground by its respective disc, thereby allowing the operating depth of the implement to be greater than the radius of the discs.

Claims (11)

CLAIMS :

1. An earthworking implement comprising a pair of spaced-apart substantially planar members adapted to be inserted at least partially in the ground and moved generally edgewise therealong, characterised in that each planar member is mounted for rotation about its transverse axis, and in that the pair of planar members are orientated so that they are divergent in both the direction of travel and in an upward direction, wherein in use, the section of soil between the planar members is lifted relative to the ground before falling back into a trough formed in the ground by the planar members.

2. An implement as claimed in claim 1, wherein each planar member is a substantially flat circular disc rotatable about a central transverse axis.

3. An implement as claimed in claim 2, wherein each disc has a fluted or corrugated peripheral edge portion.

4. An implement as claimed in claim 2, wherein each disc is angled at approximately 14° to the direction of travel.

5. An implement as claimed in claim 2, wherein each disc is angled at approximately 45° to the vertical plane.

6. An implement as claimed in claim 1, wherein each planar member is rotatably mounted on a stub axle which in turn is mounted to a pivotable support arm.

7. An implement as claimed in claim 6, wherein a bearing is provided between each planar member and its respective stub axle, the bearing having a housing located generally on the outermost side of the planar member.

8. An implement as claimed in claim 6, wherein the support arms are each biased to a predetermined operating position.

9. An implement as claimed in claim 6, wherein the support arms are pivotable about a common axis.

10. An implement as claimed in claim 1, wherein each substantially planar member comprises a hub having a plurality of radial tynes.

11. An implement as claimed in claim 1 further comprising a conduit mounted adjacent the trailing side of at least one of the planar members, said conduit having an outlet positioned to deliver material into a groove formed in the ground by the planar member.