AGRICULTURAL TILLING SYSTEM AND COMPONENTS

Abstract

An agricultural tilling assembly has an elongate structure, and at least one ground engaging tool sub-assembly. The sub-assembly includes a hub having a mounting portion, a ground engaging tool securable to the hub or integrally formed therewith, and a weight having a body with an open aperture having a mouth, the mouth configured for enabling the weight plate to be threaded over the elongate structure so that the elongate structure extends through the aperture, and the open aperture configured so that the weight plate is maneuverable over a portion of a length of the hub whilst in situ on the elongate structure and to be beatable on the mounting portion. The ground engaging tool is connectable to a respective one of the hubs of the tilling assembly whilst that hub is retained interconnected in situ on the tilling assembly, and without removing another ground engaging tool from the tilling assembly.

Claims

1. An agricultural tilling assembly comprising: an elongate structure; a plurality of ground engaging tool sub-assemblies that each include a hub, a ground engaging tool, and fasteners, wherein the ground engaging tool sub-assemblies are assembled to form the elongate structure, with the ground engaging tools being spaced apart in the elongate direction of the elongate structure; and a plurality of weight plates that each have: two major faces that are spaced apart by a peripheral edge surface, and one or more through holes through which to pass fasteners of a respective ground engaging tool sub-assembly to secure the weight plate to that ground engaging tool sub-assembly, wherein pairs of adjacent interconnected ground engaging tool sub-assemblies, of which one of those adjacent interconnected ground engaging tool sub-assemblies has one or more of the weight plates secured thereto and between the two respective ground engaging tools by the respective fasteners, are pivotable relative to one another.

2. The agricultural tilling assembly of claim 1, wherein pairs of adjacent interconnected ground engaging tool sub-assemblies are pivotable relative to one another through a range of relative pivot angles subtending approximately 80° to 90° in at least one plane.

3. The agricultural tilling assembly of claim 1, wherein pairs of adjacent interconnected ground engaging tool sub-assemblies are pivotable relative to one another through a range of relative pivot angles subtending approximately 50° to 60° in at least one plane.

4. The agricultural tilling assembly of claim 1, wherein each ground engaging tool sub-assembly is configured such that two or more weight plates are securable by the respective fasteners in a series that extends in the elongate direction from one side of the respective ground engaging tool.

5. The agricultural tilling assembly of claim 4, wherein each ground engaging tool sub-assembly is configured such that when two or more weight plates are secured to respective fasteners in the series, major faces of adjacent pairs of weight plates are in abutment.

6. The agricultural tilling assembly of claim 4, wherein each ground engaging tool sub-assembly is configured such that up to and including four weight plates are securable by the respective fasteners in a series that extends in the elongate direction from one side of the respective ground engaging tool.

7. The agricultural tilling assembly of claim 1, wherein each major face of each weight plate is a generally annular sector of at least 180°.

8. The agricultural tilling assembly of claim 7, wherein each weight plate is configured such that the peripheral edge surface has two circumferential end portions between which a gap is defined, and such that an inner cavity is defined by a radially inward portion of that peripheral edge surface, such that the weight can be located around an article by passing the article through the gap and into the inner cavity, wherein the width of the gap is less than the largest diameter of the inner cavity.

9. The agricultural tilling assembly of claim 1, wherein the peripheral edge surface of each weight plate has a radially inward portion, wherein the radially inward portion of the peripheral edge surface has reflection symmetry along a single axis, and is rotationally asymmetrical.

10. The agricultural tilling assembly of claim 9, wherein each weight plate is configured such that: the radially inward portion of the peripheral edge surface includes one or more inwardly projecting lobes, and at least one of the through holes is formed in a respective one of the lobes.

11. The agricultural tilling assembly of claim 1, wherein the hub of each ground engaging tool sub-assembly includes a hook, and an eye, and wherein the ground engaging tool sub-assemblies are assembled by interlinking the hooks and eyes of adjacent hubs to form the elongate structure.

12. The agricultural tilling assembly of claim 1, wherein the hub of each ground engaging tool sub-assembly includes through holes through which to pass the respective fasteners for securing the weight plates to the hub.

13. The agricultural tilling assembly of claim 11, wherein the hub of each ground engaging tool sub-assembly includes: through holes through which to pass the respective fasteners for securing the weight plates to the hub, and each through hole in the hub has a hexagonal recess to receive the head of one of the fasteners.

14. The agricultural tilling assembly of claim 1, wherein the hub of each ground engaging tool sub-assembly has a mounting portion, and the respective ground engaging tool is arranged to be secured to the hub or is integrally formed therewith.

15. The agricultural tilling assembly of claim 1, wherein the ground engaging tool of each ground engaging tool sub-assembly is a disc having a concave side and a convex side, and wherein the ground engaging tool sub-assemblies are configured such that the weight plates are securable to the convex side of the respective discs.

16. The agricultural tilling assembly of claim 15, wherein the ground engaging tool sub-assemblies are assembled such that the directions of concavity of the discs are oriented in substantially the same direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0132] In order that the invention may be more easily understood, embodiments will now be described, by way of examples only, with reference to the accompanying drawings, in which:

[0133] FIG. 1: is a side view of an agricultural disc chain harrow according to a first embodiment of the present invention;

[0134] FIG. 2: is a plan view of the agricultural disc chain harrow of FIG. 1;

[0135] FIG. 3: is a front perspective view of one of the disc chain assemblies shown in FIG. 1;

[0136] FIG. 4: is a first side view of the disc chain assembly of FIG. 3;

[0137] FIG. 5: is a second side view of the disc chain assembly of FIG. 3;

[0138] FIG. 6: is a first plan view of two connected disc chain assemblies of FIG. 3, showing possible range of relative pivoting movement of the two connected assemblies in a first plane;

[0139] FIG. 7: is a second plan view of two connected disc chain assemblies of FIG. 3, showing possible range of relative pivoting movement of the two connected assemblies in a second plane;

[0140] FIG. 8: is an exploded view of the disc chain assembly of FIG. 3;

[0141] FIG. 9: is a front perspective view of the hub of the disc chain assembly of FIG. 3;

[0142] FIG. 10: is a rear perspective view of the hub of the disc chain assembly of FIG. 3;

[0143] FIG. 11: is a rear perspective view of one of the weights of the disc chain assembly of FIG. 3;

[0144] FIG. 12: is a front view of the weight shown in FIG. 11;

[0145] FIG. 13: is a vertical section of the weight, as viewed along the line A-A in FIG. 12;

[0146] FIG. 14: is a front view of the disc of the disc chain assembly of FIG. 3;

[0147] FIG. 15: is a vertical section of the disc, as viewed along the line B-B in FIG. 14;

[0148] FIG. 16: is an exploded view of a disc chain assembly according to a second embodiment of the present invention;

[0149] FIG. 17: is a perspective view of a first weight of the disc chain assembly of FIG. 16;

[0150] FIG. 18: is a front view of the weight shown in FIG. 17;

[0151] FIG. 19: is a perspective view of a second weight of the disc chain assembly of FIG. 16;

[0152] FIG. 20: is a front view of the weight shown in FIG. 19;

[0153] FIG. 21: is a schematic end view showing assembly of disc segments onto the hub of FIG. 16;

[0154] FIG. 22: is a front view of a segmented disc chain part according to a third embodiment of the present invention;

[0155] FIG. 23: is a side view of the segmented disc chain part of FIG. 22;

[0156] FIG. 24: is a rear view of the segmented disc chain part of FIG. 22;

[0157] FIG. 25: is a side view of an agricultural disc chain harrow according to a fourth embodiment of the present invention;

[0158] FIG. 26: is a side elevation of an agricultural disc chain harrow according to a sixth embodiment of the present invention;

[0159] FIG. 27: is a front perspective view of one of the disc chain assemblies shown in FIG. 26;

[0160] FIG. 28: is a rear perspective view of the disc chain assembly of FIG. 27;

[0161] FIG. 29: is an exploded view of the disc chain assembly of FIG. 27;

[0162] FIG. 30: is a rear perspective view of one of the half hubs of the disc chain assembly of FIG. 27;

[0163] FIG. 31: is a rear view of the half hub of FIG. 30;

[0164] FIG. 32: is a front view of the half hub of FIG. 30;

[0165] FIG. 33: is a top view of the half hub of FIG. 30;

[0166] FIG. 34: is a front view of a disc according to a fifth embodiment of the present invention, the disc being for use in an agricultural disc chain harrow;

[0167] FIG. 35: is a perspective view of the disc of FIG. 34 is a distorted configuration for assembly onto an agricultural disc chain harrow.

DETAILED DESCRIPTION

[0168] FIGS. 1 and 2 show an agricultural tilling assembly in accordance with an embodiment of the invention. In this particular embodiment, the tilling assembly is an agricultural disc chain harrow 10. The disc chain harrow 10 has an elongate structure, and a number of ground engaging tool sub-assemblies 12 that, in this embodiment, are secured within the elongate structure. As will be appreciated from the description that follows, in this embodiment the ground engaging tool sub-assemblies 12 are assembled to form the elongate structure.

[0169] FIGS. 3 to 15 show one of the sub-assemblies 12, and its component parts, in detail. For simplicity, the description of these figures will generally refer to a single sub-assembly 12.

[0170] The sub-assembly 12 includes a hub 14, a ground engaging tool 16, and weights 18. The ground engaging tool 16 in these figures is a disc, however it will be understood that the invention is not limited to discs. In this example, the disc 16 is arranged to be releasably secured to the hub 14.

[0171] As shown in FIGS. 9 and 10, each hub 14 includes a hook 15b, and an eye 15a. The disc chain harrow 10 is assembled by interlinking the hooks and eyes 15b, 15a of adjacent hubs 14 in the harrow 10. In this particular embodiment, the hook 15b includes a transverse hole through 17a which to pass a fastener 17b. When installed, the fastener 17b prevents the end of the hook 15b disengaging from the eye 15a.

[0172] In use, disc chain harrow 10 is mounted to a harrow frame (not shown), which is towed behind a vehicle (such as a tractor, also not shown). The disc chain harrow 10 may be one of several assemblies that are mounted on the frame. The discs 16 are placed on the ground and then drawn over the ground. In this way, the discs engage the ground and will perform a harrowing function.

[0173] As shown in FIG. 10, the hub 14 has a weight mounting portion 20. In this particular embodiment, the assembly 12 is configured to mount up to four weights of differing mass. In the Figure, the assembly 12 is shown with a full complement of four weights 18.

[0174] FIGS. 11 to 13 show one of the weights 18 in detail. The weight 18 has a body with an open aperture (inner cavity 22) formed with a mouth (gap 24). The gap 24 provides a through way to the inner cavity 22. The gap 24 is configured to enable the weight 18 to be threaded over the elongate structure (in other words, passed or fed over the elongate structure), so that the elongate structure extends through, and is located within, the inner cavity 22. Further, the inner cavity 22 is configured so that the weight 18, in at least a first orientation relative to the elongate structure, and can be thereafter manoeuvred over at least a portion of a length of the hub 14 whilst that hub 14 is in situ on the elongate structure. The weight 18 is then locatable on the mounting portions 20.

[0175] The ability to add or remove weights 18 from the harrow 10 without requiring partial or full disassembly of the harrow 10 is a significant benefit. If the ground penetration is observed to be insufficient, weights can be added relatively quickly.

[0176] Conversely, if the harrow 10 is too aggressive, weights can be removed relatively quickly.

[0177] In the example of FIGS. 1 and 2, weights 18 can be threaded over the hooks and eyes 15b, 15a, and manoeuvred into position for securing against the hub 14 on “eye side”. In this way, weight can be added to the disc chain harrow 10, without requiring disassembly of the harrow 10 into its separate sub-assemblies 12. Conversely, weights 18 can be removed from the harrow 10 in situ, by a reversal of the installation procedure.

[0178] Each weight 18 has two major faces 26 that are spaced apart by a peripheral edge surface 28. Each major face 26 is a generally annular sector of at least 180°, so that the gap 24 is defined between two circumferential end portions 30a, 30b of the peripheral edge surface 28. The inner cavity 22 is defined by a radially inward portion 32 of that peripheral edge surface 28. The weight 18 is locatable around the hub 14 by passing the hub 14 through the gap 24 and into the inner cavity 22.

[0179] As is particularly evident from FIG. 12, the width of the gap 24 is less than the largest diameter of the inner cavity 22.

[0180] The inner cavity 22 has a non-circular radially inward portion 32 of the peripheral edge surface 28. In this example, the radially inward portion 32 adopts a generally X-shape (in other words, cross shape), as shown in FIG. 12. When the weight 18 is located on the mounting portion 20, the weight 18 is rotationally fixed relative to the hub 14. As will be observed from FIG. 12, in this embodiment, the radially inward portion 32 of the peripheral edge surface 28 has reflection symmetry along a single axis (which is indicated by the line S-S in FIG. 12), and is also rotationally asymmetrical.

[0181] In this example, the weight mounting portion 20 includes four recessed portions 34. Each recessed portion 34 is shaped to receive one of four inwardly projecting lobes 36 that are formed by the radially inward portion 32. Between the recessed portions 32 and the eye 15a, the weight mounting portion 20 includes an outer surface with a shape that complements that of the peripheral edge surface 28. Each of the recessed portions 34 has a general V-shape, to receive the generally V-shaped lobe 36.

[0182] The hub 14 includes four through holes 38 through which to pass bolts 40 to secure the weights 18 to the hub 14. As shown in FIG. 9, on the “hook-side” of the hub 14, each through hole 38 has a hexagonal recess to receive the head of one of the bolts 40. As shown in FIG. 8, the sub-assembly 12 includes nuts 42, four of which are to engage the bolts 40.

[0183] As shown FIG. 13, the weights 18 are configured with the lobes 36 being offset from the radially outer peripheral edge surface 28. This offset enables the weight to be positioned up against the disc 16, when both are mounted to the hub. FIGS. 6 and 7 show an interconnected pair of disc sub-assemblies 12. In each of these Figures, the “upper” sub-assembly (designated as 12U) is pivoted relative to the “lower” sub-assembly (designated as 12L). FIG. 6 indicates angle α, which is smallest maximum pivot angle that can be achieved between two adjacent and interconnected sub-assemblies 12U, 12L before the two sub-assemblies interfere and block further movement in this particular plane. Angle a is approximately 25° to 30°. FIG. 7 indicates angle β, which is largest maximum pivot angle that can be achieved between two adjacent and interconnected sub-assemblies 12U, 12L before the two sub-assemblies interfere and block further movement in this particular plane. Angle β is approximately 40° to 45°.

[0184] FIGS. 14 and 15 show the disc 16 in detail. The disc 16 has a body with an aperture 44. In this example, the disc 16 is concave, and has a circular chisel edge blade. However, the concavity, peripheral shape, and edge formation is not specific to this invention.

[0185] The aperture 44 defines an inner peripheral edge 46. The disc 16 is locatable around a disc mounting portion 48 of the hub 14. The aperture 44 is non-circular and, in this particular example, adopts a generally X-shape (in other words, cross shape), as shown in FIG. 14.

[0186] The disc 16 includes four inwardly projecting lobes 50 that surround the aperture 44. Further, the disc mounting portion 48 includes four recessed portions 52 that are each shaped to receive one of the lobes 50. Each of the recessed portions 52 has a general V-shape, to receive the generally V-shaped lobe 50. Thus, when the disc 16 is located on the mounting portion 48, the disc 16 is rotationally fixed relative to the hub 14.

[0187] The hub 14 includes four through holes 54 within the disc mounting portion 38. Additionally, the disc 16 includes four through holes 55 through which to pass bolts 56 to secure the disc 16 to the hub 14. As shown in FIG. 9, on the “eye-side” of the hub 14, each through hole 54 has a hexagonal recess to receive one of the nuts 42 that is to mate with one of the bolts 40 used to secure the disc 16 to the hub 14.

[0188] The embodiment shown in FIGS. 1 to 15 has an elongate structure of the disc chain harrow is formed from interlinked hubs that can be separated, if desired. Discs are removably mounted to one side of the hubs, and weights are removably mounted to the opposing side of the hubs. In certain alternative embodiments, the discs can be permanently fixed to an elongate structure. For example, discs can be welded to, or otherwise permanently secured, to a chain. In such embodiments, the inner annular portion of the discs can provide a hub onto which weights can be secured.

[0189] FIG. 16 shows, in an exploded view, a disc sub-assembly 112 according to another embodiment of the present invention. Component parts and features of the disc sub-assembly 112 that are similar to those of the disc sub-assembly 12 have the same reference numerals with the prefix “1”.

[0190] The ground engaging tool, which is also a disc 116 for a disc chain harrow, is formed so that it can be connected to a respective one of the hubs 114 of a disc chain harrow assembly (not shown, but formed of a plurality of sub-assemblies 112) whilst that hub 114 is retained interconnected in situ on the harrow assembly, and without the necessity to remove any other disc 112.

[0191] The ability to replace discs 116 from the harrow 10 without requiring partial or full disassembly of the harrow is a significant benefit. In the event that disc 116 are worn excessively, or are damaged, the worn discs 116 can be removed and replaced relatively quickly.

[0192] The discs 116 are shown in FIGS. 16 and FIGS. 21. In this particular embodiment, each of the discs 116 if formed of two disc segments 116a 116b. Each segment 116a, 116b includes a radially inner mounting portion 144 that, when assembled onto the hub 114 is in abutment with the hub 114.

[0193] Each segment 116a, 116b also has a radially outer ground engaging portion 160 that is supported on the respective radially inner mounting portion 144. In this particular embodiment, the disc 116 that is assembled by the two segments 116a, 116b is concave, and has a circular chisel edge blade.

[0194] The radially inner mounting portion 144 has a generally annular sector shape so as to provide two circumferential end portions 162 that each extend at least partly radially with respect to the hub 114. Further, the radially inner mounting portion 144 forms mounting formations for use in securing the mounting portion 144 to the hub 114. In this embodiment, each disc segment 116a, 116b includes two inwardly projecting lobes 150 that surround the radially inner mounting portion 144. Further, the disc mounting portion 148 on the hub 114 includes four recessed portions 152 that are each shaped to receive one of the lobes 150.

[0195] Each disc segment 116a, 116b includes two through holes 155 through which to pass bolts 156 to secure the respective segment to the hub 114.

[0196] The disc sub-assembly 112 has four weights 118a, 118b, 118c, 118d. Weights 118a to 118c are identical, but weight 118d is of slightly different construction. Weight 118a is shown in FIGS. 17 and 18, and weight 118b is shown in FIGS. 19 and 20.

[0197] Weight 118a is substantially similar to the weights 18 shown in FIGS. 12 and 13. The weight 118a differs in that the major faces 126 are both planar. Weights 118a to 118c are secured to the hub 114 in the same manner that weights 18 are secured to the hub 14.

[0198] Weight 118d differs from the weights 118a to 118c in that it has eight inwardly projecting lobes 136, and none of the lobes have through holes. As is evident from FIG. 16, weight 118d is assembled between the disc segments 116a, 116b, and at least one of the other weights 118a to 118c. The weight 118d is held in place by clamping force of the bolts 140 holding the set of weight 118 onto the hub 114.

[0199] FIGS. 22 to 24 show a disc segment 216 according to another embodiment of the present invention. The disc segment 216 is substantially similar to the disc segments 116a, 116b. Features of the disc segment 216 that are similar to those of the disc segments 116a, 116b have the same reference numerals with the prefix “1” replaced with “2”.

[0200] Disc segment 216 additionally includes a first circumferentially projecting connector, which in this embodiment is in the form of a tongue 264. The tongue projects circumferentially from an annular end face of the disc segment 216. Further, the disc segment 216 includes a second connector that is shaped to co-operate with the tongue 264. In this particular embodiment, the second connector is a keeper 266 that is shaped to receive the tongue 264.

[0201] When the disc segment 216 is secured to the hub of a disc chain harrow assembly together with another like disc segment, the tongue of each disc segment 216 is to be positioned within the keep 266. In this way, the tongue and keeper pairs 264, 266 co-operate to minimize deflection of the blade edges at the interface between the two disc segments 216.

[0202] In this example, each of the tongue 264 and keeper 266 are located on a rear side of the disc segment 216, having regard to the side of the assembled disc that is intended to approach un-tilled ground.

[0203] FIG. 25 shows an agricultural disc chain harrow 310 according to another embodiment of the present invention. Component parts and features of the harrow 310 that are similar to those of the harrow 10 have the same reference numerals with the prefix “3”.

[0204] The discs of each disc sub-assembly 312 are segmented, such that each disc is assembled from two disc segments 316, in a similar manner to the disc segments 116, 216. In this particular embodiment, each disc segment 316 includes a first circumferentially projecting connector, which in this embodiment is in the form of a tongue 364 includes a through hole 368. The tongue 364 projects circumferentially from an annular end face of the disc segment 316.

[0205] In this example, each second connector is in the form of a through hole 366. When two disc segments 316 are secured to a respective one of the hubs 314, the through hole 368 of the tongue 364, and the through hole second connector 366 are aligned so as to permit a fastener (not shown in FIG. 25) to be passed through the aligned through holes 366, 368.

[0206] FIG. 26 shows an agricultural tilling assembly in accordance with an embodiment of the invention. In this particular embodiment, the tilling assembly is an agricultural disc chain harrow 410. The disc chain harrow 410 has an elongate structure, which in this embodiment is the form of a steel multi-strand cable 415, and a number of ground engaging tool sub-assemblies 412. Each sub-assembly 412 is secured to the cable 415, as described in further detail below.

[0207] FIGS. 27 to 29 show one of the sub-assemblies 412, and its component parts, in detail. For simplicity, the description of these figures will generally refer to a single sub-assembly 412.

[0208] The sub-assembly 412 includes a hub 414, a ground engaging tool 416, and weights 418. The ground engaging tool 416 in these figures is a disc, however it will be understood that the invention is not limited to discs. In this example, the disc 416 is arranged to be releasably secured to the hub 14.

[0209] In use, disc chain harrow 410 is mounted to a harrow frame (not shown), which is towed behind a vehicle (such as a tractor, also not shown). The disc chain harrow 410 may be one of several assemblies that are mounted on the frame. The discs 416 are placed on the ground and then dragged over the ground. In this way, the discs engage the ground and will perform a harrowing function. Opposing ends of the cable 415 are provided with end connectors 470 to facilitate connection of the cable 415 to components of the harrow frame.

[0210] In this embodiment, the hub 414 is formed so as to be mountable on the cable 415, without the necessity to remove any in situ hubs 414 that are already mounted on the cable. To this end, the hub 414 comprising at least two separable parts 472a 472b (hereinafter referred to individually as “separable part 472”), one of which is shown in detail in FIGS. 30 to 33.

[0211] Each separable part 472 includes an abutment face 474 with a recessed portion 476 into which to receive the cable 415, and first retaining formations. Each separable part 472 also includes a mounting face 480, and a second retaining formations. In use of the hub 414, the two separable parts 472 are positioned with the abutment faces 474 facing one another, and the mounting faces 480 adjacent one another, as is evident from FIGS. 27 and 28. In this configuration, the recessed portions 476 are aligned to form a through way in which the cable 415 is located.

[0212] The first retaining formations 478 in each separable part include a pair of transverse holes 478a, 478b, and the hub 414 further has two nut and bolt fasteners 484. The bolt shanks of these fasteners 484 pass through the transverse holes 478a, 478b in the two separable parts 472 and mate with their corresponding nut.

[0213] On the external side of the separable part 472—in other words, opposite the abutment face 474—one of the transverse holes 478a includes a nut-shaped recess to receive a nut, while the other of the transverse holes 478b has a clearance around the hole to allow a tool to engage the head of the bolt.

[0214] The second retaining formations are used in securing the disc 416 against the mounting faces 480. In this embodiment, the second retaining formations in each separable part 472 include a pair of axial holes 482 and the hub 414 further has four nuts and bolt fasteners 486. The bolt shanks of these fasteners 486 pass through holes 455 in the disc 416 and the axial holes 482 in the two separable parts 472, and mate with their corresponding nut. Tensioning the fasteners 486 thus secures the disc 416 to the hub 414.

[0215] On the rear side of the separable part 472—in other words, opposite the mounting face 480—each of the axial holes 482 includes a nut-shaped recess to receive a nut of one of the fasteners 486. As shown in FIG. 27, the heads of the bolts are accessible from the front, working face of the disc 416.

[0216] The recessed portions 476 are configured such that tensioning the fasteners 476 applies a clamping force to the cable 415. In addition, as shown particularly in FIGS. 31 and 32, the abutment face of each separable part 472 include engagement formations within the recessed portion 476. In this embodiment, the engagement formations are in the forms of ribs 488. When the hub 414 is mounted on the cable 415, the ribs 488 engage the outer surface of the cable 415 and resist relative movement between the hub 414 and cable 415.

[0217] The mounting face 480 of each separable part 472 has a pair of location formations 490 that facilitate location of the disc 416 on the mounting faces 480 relative to the axial holes 482. Each of the location formations 490 has a shape that compliments the lobes 450 on the disc 416.

[0218] Each of the separable parts 472 includes a third retaining formation 492, and the hub 414 further has a locking member 494. The third retaining formations 492 and locking member 494 are shaped to interengage with one another. A weight 418 is locatable around the hub 414, and the locking member 494 brought into interengagement with the third retaining formations 492 and operated to retain the weight 418 in position on the hub 414. The weight 418 has a peripheral edge surface that defines an inner cavity 422. The hub 414 has an outer surface shape that complements that of the inner cavity 422.

[0219] As shown in FIGS. 28 and 29, the locking member 494 includes a clip portion that interengages with the third retaining formations 492, and a pair of threaded fasteners that extend through internally threaded apertures in the clip portion. In use, the threaded fasteners are operable to bear against the weight 418 to thereby retain the weight 418 in position on the hub 414. As will be appreciated from FIG. 28, the weight 418 is captured between the disc 416 and the fasteners of the locking member 494.

[0220] The harrow 410 enables the spacing between adjacent hubs 414 to be varied quickly. The spacing can be varied by removing or adding a number of hubs from the cable 415, or by adjusting the positioning of each hub along the length of the cable 415 and adding or removing hubs as required. In this way, the farmer has an ability to adjust the harrow to better suit the needs of the particular soil or soil condition of the ground to be harrowed.

[0221] FIGS. 34 and 35 show a ground engaging tool 516 for mounting on a hub (not shown) of an elongate agricultural tilling assembly according to another embodiment. The ground engaging tool 516 in these figures is a disc, however it will be understood that the invention is not limited to discs.

[0222] The disc 516 includes a mounting portion 551 that has a generally annular shape, and that defines a radially inner edge that is to locate about the hub, and mounting holes 555 for use in securing the mounting portion 551 to the hub. The disc also has a radially outer ground engaging portion 553 that is supported by the mounting portion.

[0223] The disc 516 is formed with a first slit 596 that extends between the radially inner edge and the radially outer edge portion of the disc 516. In this particular embodiment, the disc 516 is formed with a second slit 598 that extends from the radially inner edge to a terminal end that is spaced inwardly of the radially outer edge portion of the disc 516. In this embodiment, the terminal end of the second slit 598 includes a stress-relieving formation 599.

[0224] The disc 516 is resiliently deflectable to adopt a configuration in which the first slit 596 is open. FIG. 35 shows the disc in a deflected configuration. In this configuration, the yield stress of the disc material has not been exceeded, and upon removal of the deflecting force the disc 516 will be restored to its natural configuration.

[0225] As will be appreciated, when the disc 516 is in the deflected configuration, a throughway is formed enabling the disc 516 to be threaded over a part of the elongate agricultural tilling assembly. By way of example only, when in the deflected configuration, the disc 516 could be passed over the eye 15a of the harrow 10, or alternatively over the cable 415 of the harrow 410.

[0226] In the illustrated embodiments, the ground engaging tool is generally disc shaped such that the radially outer ground engaging portion is a radially outward facing blade edge that engages the ground. It will be appreciated that the ground engaging tool can have different ground engaging portions, without departing from the invention. For example, the ground engaging tool could be a dog-leg harrow, a spiked-wheel, a scalloped or saw-tooth blade.

[0227] Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0228] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0229] While a particular embodiment of the present agricultural tilling system and components has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.