GB1598599A - Soil cultivating implements - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SOIL CULTIVATING IMPLEMENTS (71) We, C. VAN DER LELY N.V., of 10, Weverskade, Massland, The Netherlands, a Dutch Limited Liability Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to soil cultivating implements or machines of the kind which comprise a plurality of soil working members that are rotatable about corresponding nonhorizontal axes, each soil working member having a carrier provided with at least one soil working element which projects downwardly therefrom and which is freely pivot ally connected thereto. The expression "implement(s) or machine(s)" will be shortened to "implement(s)" alone throughout the remainder of this specification for the sake of brevity.

According to the invention, there is provided a soil cultivating implement of the kind set forth, wherein a soil working extension is provided on a freely pivotable support of each of at least some of said soil working elements, said support being connected to the respective carrier, and wherein each such extension is disposed perpendicular or substantially perpendicular to the length of the corresponding soil working element.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a plan view of a soil cultivating implement in accordance with the invention connected to the rear of an agricultural tractor, Figure 2 is an elevation, to an enlarged scale, illustrating one soil working member of the implement of Figure 1 in greater detail, Figure 3 is a plan view as seen in the direction indicated by an arrow III in Figure 2, Figure 4 is a section taken on the line IV-IV in Figure 2, and Figure 5 illustrates an alternative bearing construction and arrangement to that which can be seen at the top right-hand corner of Figure 4.

Referring to the accompanying drawings, and particularly to Figure 1 thereof, the soil cultivating implement which is illustrated comprises a hollow box-section frame portion 1 which extends substantially horizontally transverse, and usually (as illustrated) substantially horizontally perpendicular, to the intended direction of operative travel of the implement which is indicated by an arrow A in Figure 1 of the drawings. Eight parallel and non-horizontally disposed shafts 2 are rotatably mounted in the hollow frame portion 1 in a single row with their longitudinal axes (axes of rotation) a spaced apart from one another at regular intervals which advantageously, as in the embodiment illustrated, have magnitudes of substantially 375 millimetres. It will be noted that each shaft 2 will, during the operation of the implement, usually occupy a position in which it is vertically or substantially vertically disposed.

Each shaft 2 projects downwardly from beneath the bottom of the hollow frame portion 1 and the downwardly projecting portion thereof has a corresponding soil working member 3 firmly but releasably secured to it in a manner which will be further described below. Each shaft 2 is provided, inside the hollow frame portion 1, with a corresponding straight-toothed or spur-toothed pinion 4, the size and arrangement of the pinions 4 being such that the teeth of each pinion are in mesh with those of the or each immediately neighbouring pinion in the single row thereof. Although there are eight of the shaft 2, soil working members 3 and pinions 4 in the embodiment which is being described, it is noted that this is by no means essential and that smaller or larger numbers thereof could also be provided.

A substantially vertically disposed shaft 5 is rotatably mounted in the hollow frame portion 1 at a location which is close to the rear of that frame portion with respect to the direction A and substantially midway along the transverse length of the frame portion.

The shaft 5 projects above the top of the frame portion 1 and into a gear box 7 that is fastened on top of the frame portion 1. The shaft 5 carries, inside the frame portion 1, a straight-toothed or spur-toothed pinion 6 which is considerably smaller in size than any one of the identical pinions 4 and whose teeth are in driving mesh with one, but not the other, of the centre pair of pinions 4 of the row of eight such pinions. The upper end of the shaft 5 is provided, inside the gear box 7, with a bevel pinion (not shown) which is in driven mesh with a further bevel pinion (also not shown) carried by a substantially horizontally disposed shaft 8 that is in parallel or substantially parallel relationship with the direction A and whose leading splined or otherwise keyed end projects forwardly from the front of the gear box 7 so that said shaft 8 can serve as a rotary input shaft. When the implement is in use, the leading splined or otherwise keyed end of the shaft 8 is placed in driven connection with the rear power take-off shaft of an agricultural tractor or other operating vehicle by way of an intermediate telescopic transmission shaft 8A, which is of a construction that is known per se, having universal joints at its opposite ends. The opposite ends of the hollow frame portion 1 are closed by parallel and substantially vertically disposed side plates 9 that are both in parallel or substantially parallel relationship with the direction A. The side plates 9 of the frame portion 1 will be referred to again below.

Each of the rotary soil working members 3 comprises a substantially horizontally disposed carrier 10 (Figures 2 and 3), said carrier 10 having a central internally splined hub 11 that co-operates with matching external splines on the downwardly projecting portion of one of the shafts 2 (see Figure 3).

The central hub 11 of each carrier 10 is prevented from becoming axially detached from the corresponding shaft 2 by the provision of a fastening nut 12 and, preferably, a co-operating washer, the nut 12 being installed on a short screwthreaded lowermost part of the shaft 2 concerned. Preferably, as shown somewhat diagrammatically in Figure 2 of the drawings, a split pin or other fastening is provided so as positively to ensure that the nut 12 cannot work loose on the screwthreaded part of the corresponding shaft 2 as a result of, for example, the vibration and mechanical shocks to which the nut 12 is inevitably subject when the implement is in use.

Each carrier 10 comprises two diametrically opposed straight arms 13 which radiate, with respect to the corresponding axis a, from opposite sides of the hub 11 concerned.

The two arms 13 of each carrier 10 are of equal lengths and the radially outermost ends thereof have correspo ding substantially cylindrical and sleeve-like holders 14 integrally or at least rigidly secured to them.

At least an upper portion of each holder 14 is of gentle upwardly tapering configuration and each holder 14 projects both upwardly above, and downwardly beneath, the corresponding arm 13 although it will be evident from Figure 2 of the drawings that the extent of downward projection thereof beneath the corresponding arm 13 is greater than is the extent of upward projection thereof above that arm. The holders 14 occupy positions in which their longitudinal axes are obliquely inclined to both the horizontal and the vertical but, as seen in a horizontal direction that is perpendicular to the common longitudinal axis of the two arms 13 of one carrier 10 (i.e. as seen in Figure 2 of the drawings), the longitudinal axes of the corresponding two holders 14 both appear to be in parallel relationship with the axis of rotation a of the soil working member 3 concerned.

The hollow interior of each sleeve-like holder 14 is stepped and receives, from the lower end, a corresponding stub shaft 16 whose longitudinal axis b coincides with that of the sleeve 14 under consideration. Each such stub shaft 16 is pivotally/rotatably received in the corresponding holder 14 with the aid of opposed lower and upper tapered roller bearings 15, said bearings 15 cooperating with internal steps of the holder 14 concerned and with stepped portions of the stub shaft 16 which they surround. Thus, the lower bearing 15 of each pair has an outer race whose upper end abuts against an internal step of the corresponding holder 14 whilst, similarly, the corresponding upper bearing 15 has an outer race whose lower end abuts against a further, but spaced, internal step of said holder 14. The upper end of each stub shaft 16 is formed with an internally screwthreaded axially extending blind bore and, when said stub shaft 16 is installed in its holder 14, the shank of a bolt 17 co-operates with said bore in fastening a cap 18 thereto in such a position that said cap 18 substantially closes the upper end of the open interior of the holder 14 concerned. It will be seen from Figure 4 of the drawings that the head of each bolt 17 is recessed into the cap 18 with which it co-operates and that a rotary seal is provided between each cap 18 and the top of the underlying upper tapered roller bearing 15, it being remembered, of course, that the stub shafts 16 are turnable about the axes b inside the holders 14.

Figure 5 of the drawings illustrates an alternative embodiment in which stub shafts 1 6A are employed in place of the previously described stub shafts 16, said stub shafts 16A being free of steps throughout their lengths except at their lowermost ends which adjoin corresponding supports 19 that will be referred to again below. The stub shafts 16A are freely turnable in upper and lower plain bearings 15A whose outer surfaces are lodged in corresponding enlarged diameter portions of the central bores through corresponding holders 14A which holders 14A are identical, or substantially identical, in construction to those of the previously described holders 14, except that they are of smaller internal diameter. Each lower plain bearing 15A extends between the step at the lower end of the stub shaft 16A concerned and the lower end of a substantially central reduced diameter shoulder of the bore through the corresponding holder 14A whilst each upper plain bearing 15A extends between the upper end of said shoulder and the lower surface of a washer that is mounted at the upper end of the associated stub shaft 16A by one of the bolts 17 which is screwed axially into a blind bore of said stub shaft 16A, a resilient antiloosening washer preferably also being provided beneath the head of each bolt 17 as can be seen diagrammatically in Figure 5 of the drawings. It can also be seen in Figure 5 that the head of the bolts 17, the washers and the resilient washers that have just been mentioned are all disposed within a downwardly tapering recess 1 8A at the top of each holder 14A.

The intended directions of operative rotation of the soil working members 3 are indicated by arrows B in Figures 1 and 3 of the drawings and it can be seen that, with respect to the corresponding direction B, each stub shaft 16 or 1 6A is obliquely inclined upwardly and rearwardly from its lower to its upper end, the longitudinal axis b thereof being inclined at an angle a of substantially 15 to a plane N-N which contains the axis of rotation a of the member 3 concerned and which is perpendicular to a further plane M-M that contains the longitudinal axis b of one of the two stub shafts 16 or 16A of said member 3, the plane M-M also being in parallel relationship with the axis of rotation a of that member 3.

The lower end of each stepped stub shaft 16 or plain stub shaft 16A projects from beneath the bottom of the corresponding holder 14 or 14A and is there provided with one of the supports 19 to which reference has been made above. It will be seen from the drawings that, in the usual operative position of each soil working member 3 that is illustrated, the corresponding supports 19 extend obliquely downwardly and rearwardly with respect to the corresponding directions of rotation B and are of enlarged vertical extent towards those rear ends as compared with the leading ends thereof which are close to the stub shafts 16 or 1 6A concerned. The vertically enlarged rear end portion of each support 19 has the upper end of a corresponding soil working element 21 firmly but releasably secured to it by a pair of substantially horizontally disposed bolts 20 that are located at different horizontal levels, the "upper" bolt 20 being in advance of the "lower" bolt 20 with respect to the direction B concerned. Thus, during operation, each soil working element 21 will be located substantially constantly to the rear of the corresponding stub shaft axis b with respect to the corresponding direction of rotation B, said element 21 occupying a trailing disposition from top to bottom with respect to that direction B. The longitudinal axis of each strip-shaped element 21 is inclined at an angle of substantially 5" to the corresponding plane N-N (see Figure 4). Thus, the leading edge, with respect to the corresponding direction of rotation B, of each strip-shaped element 21, which leading edge is parallel to the longitudinal axis of the same element, is inclined to the longitudinal axis b of the stub shaft 16 or 16A concerned at an angle of substantially 20 . The strip-shaped material, which will usually be metallic, from which each element 21 is made will usually be in substantially tangential relationship with an imaginary circular cylindrical figure that is centred upon the corresponding axis of rotation a and the leading edge of said element 21, with respect to the corresponding direction of rotation B, is bevelled to form a cutting edge 22 (Figures 2 and 4). Each cutting edge 22 extends downwardly throughout substantially the whole of the free length of the element 21 concerned from the lower edge of the respective support 19.

Each support 19 is provided, towards the front thereof with respect to the corresponding direction of rotation B and in substantially axial register with the respective stub shaft 16 or 16A, with two laterally projecting opposed lugs 23, both lugs 23 thus being in substantially perpendicular relationship with the corresponding axis b. The two lugs 23 of each pair have a corresponding extension strip 25 firmly but releasably secured to them by two bolts 24. Each extension strip 25 extends perpendicularly from both sides of the general plane of the corresponding soil working element 21 at a location which is close to the leading edge of the uppermost end of that element. When, as will usually be the case, the corresponding axis of rotation a is vertically or substantially vertically disposed, each extension strip 25 is in obliquely inclined relationship with both the horizontal and the vertical, its rear edge, with respect to the corresponding direction of rotation B, being substantially straight throughout its length. The front edge thereof, with respect to the same direction B, is not straight but comprises two forwardly convergent straight portions that are of equal length and which meet at a somewhat shallow point which will usually, as illustrated, be coincident or substantially coincident with the corresponding plane M-M. The relative disposition of the hub 11, the arms 13 and holder 14 or 14A of each soil working member 3 is such that each stub shaft 16 or 1 6A is located substantially wholly in advance of the corresponding plane N-N with respect to the intended direction of operative rotation B of the soil working member 3 concerned (see Figure 3).

The relationship which has just been mentioned between the hub 11, arms 13 and holders 14 or 14A of each soil working member 3 is also such that, in an imaginary plane which is perpendicular to the axis of rotation a of that member 3, a line connecting one of the corresponding axes b and said axis of rotation a is inclined to the corresponding plane N-N at an angle of between 15 and 20 inclusive. Such an imaginary plane may, for example, contain the coincident longitudinal axes of the two arms 13 of the corresponding carrier 10 in which case said connecting line will be the longitudinal axis of the arm 13 concerned and will extend between a location on the corresponding axis b towards the upper end of the stub shaft 16 or 1 6A concerned and the axis of rotation a which coincides with the longitudinal axis of the shaft 2 to which the soil working member 3 is firmly but releasably secured. The opposite ends of each extension strip 25 are perpendicularly inclined to the rear edge, with respect to the corresponding direction B, of that strip and are thus obliquely inclined to the two straight and forwardly convergent portions of the leading edge of the same strip. Each soil working element 21 advantageously has an overall top to bottom length of substantially 300 millimetres and a width (as seen in Figure 4) of substantially 60 millimetres. The length, in a direction parallel to its rear edge, of each extension strip 25 is preferably substantially half the overall length of one of the soil working elements 21 and may thus, in the case of the embodiment which is being described, have a magnitude of substantially 150 millimetres.

The two side plates 9 of the hollow frame portion 1 are provided, close to their leading extremities, with corresponding strong pivots 26 which are substantially horizontally aligned in a direction which is substantially perpendicular, or at least transverse, to the direction A. Arms 27 which extend generally rearwardly from the pivots 26 with respect to the direction A are turnable upwardly and downwardly about those pivots 26 alongside the corresponding plates 9, said arms 27 projecting by some distance beyond the rear edges of the side plates 9. Each side plate 9 is substantially sector-shaped and a plurality of holes are formed close to the broad upright rear edge thereof at equal distances from the axis which is defined by the pivots 26. Each arm 27 is also formed with at least one hole at the same distance from the axis that is defined by the pivots 26 and retaining bolts 28 are provided for horizontal entry through the holes in the arms 27 and chosen ones of the holes in the side plates 9 to retain the arms 27 firmly but releasably in a corresponding angular setting about the axis which is defined by the strong pivots 26.

Substantially horizontally aligned bearings are carried by the rearmost ends of the arms 27 and an open-work ground roller 29, that extends throughout substantially the whole of the combined working width of the soil working members 3, is carried by said bearings in a freely rotatable manner. The roller 29 acts as a rotatable supporting member of the implement in partially supporting the latter from the ground surface when it is in operation. The roller 29 also acts, in its own right, as a further soil working member of the implement and will serve to crush any exceptionally unbroken lumps of soil that may remain at or near the surface thereof after treatment by the immediately foregoing soil working members 3. The roller 29 comprises a central axially extending and preferably tubular support 32 to which a plurality, such as five, of circular support plates 31 are fastened at regulated spaced apart intervals, two of said support plates 31 being located close to the opposite ends of the central support 32. The support plates 31 are substantially vertically disposed in parallel relationship with one another and parallel or substantially parallel relationship with the direction A and each of them is formed, close to its periphery, with a circular row of regularly spaced apart holes. A plurality of elongate elements 30 of either rod-shaped or tubular formation are entered lengthwise through the holes in the successive support plates 31 and are preferably so arranged that, as can be seen in Figure 1 of the drawings, they extend in a shallow helically wound pattern around the central support 32. The roller 29, is of course, bodily displaceable upwardly and downwardly relative to the frame portion 1 and to the soil working members 3 by turning the arms 27 upwardly or downwardly about the aligned pivots 26 in the manner described above, using the retaining bolts 28 to maintain any newly chosen level of the roller 29 relative to the frame portion 1 as long as may be required.

It will be appreciated that the level of the roller 29 which is chosen relative to that of the frame portion 1 and soil working mem bers 3 is a principal factor in determining the maximum depth of penetration of the soil working elements 21 of said members 3 into the ground which is possible when the implement is in operation.

Two supports 33 extend substantially hori zontally parallel to the direction A at loca tions above the top of the hollow frame portion 1 and at short distances inwardly towards the centre of that frame portion from the two side plates 9 thereof. The opposite ends of the supports 33 are secured to brackets which are mounted at the front and rear of the frame portion 1. Each support 33 carries, at the side thereof which faces towards the neighbouring end of the hollow frame portion 1, front and rear pairs of lugs 34 and each pair of lugs 34 has one end of a corresponding arm 35 turnably connected to it by a pivot pin which defines an axis that is substantially horizontally parallel to the direction A, the two pivot pins which correspond to the two pairs of lugs 34 which are carried by the same support 33 being in axially aligned relationship. The two arms 35 that correspond to each support 33 extend, in convergent relationship, towards the neighbouring end of the hollow frame portion 1 and over the upper edge of the corresponding end plate 9. The two arms 35 are then bent over downwardly and lower end regions thereof carry a corresponding substantially vertically disposed shield plate 36 which is in parallel or substantially parallel relationship with the direction A. The lower edges of the shield plates 36 are arranged to slide forwardly over the ground surface in the direction A during operation of the implement and rearwardly with respect to that direction during manoeuvring. Each shield plate 36 is upwardly and downwardly displaceable about the substantially horizontal axis which is defined by the pivot connections between the corresponding pair of arms 35 and the corresponding pairs of lugs 34 so that said shield plate 36 can turn upwardly and downwardly about said axis to match undulations in the surface of the ground which it may meet with during operation or manoeuvring. The two shield plates 36 are located close to the opposite ends of the row of eight soil working members 3 and cooperate with the two members 3 which are at the opposite ends of said row in crumbling the soil as intensively at the margins of the broad strip thereof that is worked by the implement as it is at locations which are closer to the middle of that broad strip. The shield plates 36 minimise ridging of the soil at the margins of the broad strip of worked land and substantially prevent stones and other hard objects from being flung laterally of the path of travel of the implement by the elements 21 of the rapidly rotating soil working members 3. The danger of injury or damage to bystanders, livestock and property from this cause is thus greatly reduced, if not entirely eliminated.

The front of the hollow frame portion 1, with respect to the direction A, is provided with a coupling member or trestle 37 at a location which is substantially midway between the general planes of the two frame portion side plates 9. The coupling member or trestle 37 is of substantially triangular configuration as seen in front or rear elevation and substantially the apex thereof is connected by downwardly divergent tie beams 39, for strengthening purposes, to locations which are close to the rear ends of two further substantially horizontal supports 38 that are similar in disposition to the supports 33 but that are located much closer to the midpoint of the hollow frame portion 1. The coupling member or trestle 37 is constructed and arranged for connecting the implement to the three-point lifting device or hitch at the rear of an agricultural tractor or other operating vehicle in a manner that is generally known per se and that is illustrated, somwhat diagrammatically, in Figure 1 of the drawings.

In the use of the soil cultivating implement that has been described, its coupling member or trestle 37 is connected to the rear ends of the upper and lower lifting links of a threepoint lifting device or hitch at the rear of an agricultural tractor or other operating vehicle and the known telescopic transmission shaft 8A which has universal joints at its opposite ends is employed to place the rear power take-off shaft of the same tractor or other vehicle in driving connection with the forwardly projecting leading end of the rotary input shaft 8 of the gear box 7. If required, the roller 29 may be bodily raised or lowered relative to the frame portion 1 and to the soil working members 3, before work commences, to adjust the maximum depth to which the soil working elements 21 of the members 3 will be able to penetrate into the ground. As the implement moves operatively in the direction A over soil that is to be cultivated, the drive that is applied to the rotary input shaft 8 of the gear box 7 for the rear power take-off shaft of the agricultural tractor or other operating vehicle causes the eight shafts 2 and soil working members 3 to revolve in the directions B that are indicated in Figures 1 and 3 of the drawings so that each member 3 will revolve in the opposite direction to its immediate neighbour or to both of its immediate neighbours. The soil working elements 21 of the various members 3, will, at this time, occupy substantially the positions thereof that are shown in the drawings, the effective spacing between the two elements 21 of each member 3 being greater than the distance between the axes of rotation a of immediately neighbouring members 3 so that the eight strips of land which are worked by the individual members 3 overlap one another. Each element 21 is freely turnable about the corresponding axis b which axis is located in front of that element 21 with respect to the corresponding direction of rotation B. Thus, each element 21 can move pivotally to match the constantly varying resistance to its passage through the soil in such a way as to ensure a minimum of power consumption by the implement and so as to enable any element 21 which is blocked by an embedded stone or the like to deflect to avoid that obstacle. The upward and rearward, with respect to the corresponding direction B, slope of each axis b greatly facilitates the deflectability of the corresponding element 21 which, if deflected laterally, will automatically rise in level. to a small extent as it turns about said axis b.

Despite the leading cutting edge 22 of each element 21, said element primarily produces a crumbling effect upon the soil rather than a slicing effect. In fact. the soil tends to break up along its own natural lines of fracture such as root paths, earth-worm burrows and the like. The extension strips 25 which extend perpendicularly, or at least transversely, with respect to the directions of rotation B of the soil working members 3, also cultivate the soil during the use of the implement and act panicularly upon an upper layer of the top soil which they vigorously displace and crumble.

It will be remembered that the extension strips 25 are releasably secured to the lugs 23 of each support 19 by a pair of bolts 24.

Thus. the extension strips 25 may be used, as shown in the drawings. or, alternatively. may be temporarily removed from the supports 19. Their provision or omission depends upon the particular cultivation work which is to be undertaken. For example, the use of the extension strips 25 is desirable during spring cultivations when seed beds are to be prepared whereas, in the autumn/fall season, the implement may be used in the prewintering cultivation of stubble fields and the like at which time a better result is obtained by temporarily removing the extension strips 25. It is acknowledged that, when all of the extension strips 25 are removed from the soil working members 3. the implement is no longer an implement in accordance with the invention which is as set forth in the follow

Claims (21)

ing claims. WHAT WE CLAIM IS:

1. A soil cultivating implement of the kind set forth, wherein a soil working extension is provided on a freely pivotable support of each of at least some of said soil working elements, said support being connected to the respective carrier, and wherein each such extension is disposed perpendicular or substantially perpendicular to the length of the corrcsponding soil working element.

2 An implement as claimed in claim 1, whercin the axes about which said soil working elements are freely pivotable are inclined upwardly at angles of substantially 20 to the fronts, with respect to the intended directions of operative rotation of the respective soil working members, of the corresanding soil working elements.

3. An implement as claimed in claim I or 2. wherein the axes about which said soil working elements are freely pivotable are located. during the operation of the implement, substantially constantly in front of the corresponding elements with respect to the directions of rotation, at that time. of the soil working members of which said elements form parts.

4. An implement as claimed in any preceding claim, wherein the axes about which said soil working elements are freely pivotable are inclined upwardly and rearwardly with respect to the intended directions of operative rotation of the corresponding soil working members.

5. An implement as claimed in any preceding claim, wherein the axes about which said soil working elements are freely pivotable are contained in planes that extend substantially parallel to the axes of rotation of the corresponding soil working members.

6. An implement as claimed in any preceding claim, wherein the carrier of each of at least said some of the soil working members comprises two arms that are in substantially coaxial relationship.

7. An implement as claimed in any preceding claim, wherein each axis about which one of said soil working elements is freely pivotable is inclined at an angle of substantially 15 to a plane which contains the axis of rotation of the corresponding soil working member and which is also perpendicular to a further plane that contains the pivotal axis concerned and that is parallel to said axis of rotation.

8. An implement as claimed in any preceding claim, wherein each soil working extension is mounted on the corresponding support in a releasable manner.

9. An implement as claimed in any preceding claim, wherein each soil working extension is of elongate configuration.

10. An implement as claimed in any preceding claim, wherein each soil working extension is secured in its appointed position by at least one fastening which is located substantially centrally thereof.

11. An implement as claimed in any preceding claim, wherein each soil working extension has a tip or point at the front thereof with respect to the intended direction of operative rotation of the corresponding soil working member.

12. An implement as claimed in claim 11, wherein said tip or point is afforded by the junction between two edge portions of the extension concerned that converge forwardly with respect to the intended direction of operative rotation of the corresponding soil working member.

13. An implement as claimed in claim 12, wherein said edge portions are both substantially straight.

14. An implement as claimed in claim 11 or 12, wherein said edge portions have substantially equal lengths.

15. An implement as claimed in any preceding claim, wherein the rear of each soil working extension, with respect to the intended direction of operative rotation of the corresponding soil working member, is substantially straight.

16. An implement as claimed in claim 15, wherein the opposite ends of each soil working extension are in substantially perpendicular relationship with said rear thereof.

17. An implement as claimed in claim 9 or in any one of claims 10 to 16 when read as appendant to claim 9, wherein each soil working extension has a length which is substantially half that of the corresponding soil working element.

18. An implement as claimed in any preceding claim, wherein the axes about which said soil working elements are freely pivotable are afforded by stub shafts or the like which are rotatably mounted in corresponding holders.

19. An implement a claimed in claim 18, wherein each holder is located substantially wholly in advance, with respect to the intended direction of operative rotation of the corresponding soil working member, of a plane which contains the axis of rotation of that soil working member and that is perpendicular to a further plane which contains the pivot axis concerned and which is parallel to said axis of rotation.

20. An implement as claimed in claim 3 or in any one of claims 4 to 19 when read as appendant to claim 3, wherein each soil cultivating element is of elongate configuration and substantially constantly occupies a trailing position with respect to the direction of rotation of the corresponding soil working member during the use of the implement.

21. A soil cultivating implement of the kind set forth, substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings or with reference to Figures 1 to 4 as modified by Figure 5 of those drawings.