GB2142811A - Soil cultivating implements - Google Patents

Abstract

A soil cultivating implement has a ground-engaging packer roller 8 located behind soil working members and substantially oblong scrapers 11 co-operate with the external surface of the roller 8 between groups of soil-penetrating teeth 10. Each scraper 11 is carried by a foot 12 mounted at the lower end of an upright arm 13 and each arm 13 is connected to a common carrier 20 of circular cross-section by at least one U-bolt 18 and a pair of clamping shoes 21. The nuts 19 of the U-bolt can be tightened so that each arm 13 can occupy a normal working position (full lines) in which its scraper 11 just makes scraping contact with the cylinder 9 but not such firm contact that rapid wear will occur. The degree of tightness of the nuts 19 is sufficient reliably to maintain this position under normal working conditions but, should a jagged stone or the like become tightly jammed between the neighbouring groups of teeth 10 so that it will tend to damage the scraper 11 and/or its mounting, the U-bolt 18 and shoes 21 will slip angularly around the common carrier 20 to move the scraper 11 into a withdrawn position (broken lines) before any damage occurs. <IMAGE>

Description

SPECIFICATION Soil cultivating implements This invention relates to soil cultivating implements or machines and particularly, but not exclusively, to those which are intended for the formation of seedbeds, such implements or machines being of the kind which comprise a plurality of soil working members and a ground-engaging-packer roller located to the rear of said soil working members relative to the intended direction of operative travel of the implement or machine, the packer roller comprising a cylinder upon which are arranged a plurality of groups of projecting teeth between which groups extend corresponding soil-shedding scrapers supported by lower end regions of upwardly extending arms that are connected to a carrier therefor. The term "implement(s) or machine(s)" is shortened to "implement(s)" alone throughout the remainder of this document for the sake of brevity.

The scrapers of such known implements are required to perform an efficient soil-shedding action without, however, becoming worn at a fast rate and initial, and subsequent, adjustments thereof to maintain this condition can prove difficult and time consuming, particularly when the implement in question is of relatively large working width. The present invention seeks very greatly to reduce the difficulty and tediousness of maintaining the scrapers in optimum soil-shedding positions, without becoming rapidly worn, and to provide a construction by which damage to the scrapers and their mountings from stones and other hard objects jammed between the roller teeth can be very significantly reduced, if not entirely eliminated.

According to the invention, there is provided a soil cultivating implement of the kind set forth, wherein said carrier is of circular or substantially circular cross-section and said arms are adjustably clamped to the carrier by means which is angularly displaceable around that carrier.

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 constructed in accordance with the invention shown connected to the rear of an agricultural tractor, Figure 2 is a section, to an enlarged scale, taken on the line Il-Il in Figure 1, Figure 3 is a rear elevation as seen in the direction indicated by an arrow Ill in Figure 2, and Figure 4 is a plan view as seen in the direction indicated by an arrow IV-IV in Figure 2.

Referring to the accompanying drawings, the soil cultivating implement that is illustrated therein is in the form of a rotary harrow that is intended principally, but not exclusively, for preparing seedbeds in previously used agricultural land. The implement comprises a hollow, box-section frame portion 1 that extends substantially horizontally transverse and usually, as illustrated, substantially horizontally perpendicular, to the intended direction of operative travel of the implement that is indicated in Figures 1 and 2 of the drawings by an arrow A.A plurality, of which there are twelve in the embodiment that is being described, of upwardly extending and usually vertically or substantially vertically disposed shafts 2 are rotatably mounted in upper and lower walls of the hollow frame portion 1 so as to lie in a single row that extends substantially horizontally perpendicular to the direction A with each shaft 2 parallel to its neighbours and with the longitudinal axes/axes -of rotation of the twelve shafts spaced apart from one another at regular intervals which advaritageously, as illustrated, but not essentially each have a magnitude of substantially 25 cms.Each shaft 2 projects downwardly from beneath the bottom of the hollow frame portion 1 and the downwardly projecting portion thereof has firmly but releaseably secured to it a corresponding soil working member that is not illustrated in the drawings. Each such rotary soil working member comprises a substantially horizontally disposed support or carrier having two arms which project in radially opposite directions from a central hub mounted on the downwardly projecting portion of the shaft 2 concerned. The outer ends of the two symetrically identical arms of each support or carrier are provided with corresponding sleeve-like holders in which upper fastening portions of soil working tools in the form of rigid tines are firmly but releaseably received.

The opposite ends of the hollow frame portion 1 are closed by corresponding substantially, but not exactly, oblong side plates 3 that extend substantially vertically parallel to one another and to the direction A, each side plate 3 projecting vertically above the top of the hollow frame portion 1 itself by a significant distance and also extending rearwardly behind that hollow frame portion 1 with respect to the direction A. Upper leading regions of the two side plates 3 are provided with substantially horizontally aligned pivots 4 upon which pivots 4 the leading ends of corresponding arms 5 are mounted so that those arms 5 are upwardly and downwardly turnable about the axis defined by the aligned pivots 4 immediately alongside the respective plates 3 at the sides of those plates 3 which face the centre of the implement.A major leading portion and a relatively short rear portion of each arm 5 are parallel or substan tially parallel to one another and are interconnected by a downwardly and rearwardly inclined portion. The relatively short rear portion of each arm 5 has bolted to it a corresponding downwardly and rearwardly inclined support 6 and a lower portion of each support 6 rotatably carries, by way of a horizontal bearing located in a corresponding bearing housing 7, a stub shaft which defines the axis of rotation a of a rear gound roller 8 of the implement.

Adjusting mechanisms 24 which comprise manually rotatable screw-threaded shanks having crank handles at their upper ends are mounted at the rear of the hollow frame portion 1 and alongside the corresponding side plates 3, each mechanism 24 being of a known construction that enables its screwthreaded shank or spindle to be rotated in either direction without significant axial displacement. Each arm 5 carries a corresponding pivotally mounted block through which the screw-threaded shank or spindle of the corresponding mechanism 24 extends so that, upon rotating the crank handles at the upper ends of the mechanisms 24 in appropriate directions, the arms 5 will be turned either upwardly or downwardly relative to the hollow frame portion 1 and the soil working members carried by the shafts 2 about the substantially horizontal axis that is defined by the aligned pivots 4.Although the mechanisms 24 will themselves retain the arms 5, and thus the roller 8, in a chosen position relative to the frame portion 1 and its soil working members, arresting clamps 25 (Figure 2) are provided which can be tightened to interconnect upper regions of the supports 6 and rear edge regions of the frame portion side plates 3 significantly to reinforce the maintenance of any chosen level of the ground roller 8 relative to the frame portion 1. It is only necessary temporarily to loosen the arresting clamps 25 when an adjustment of this level is to be made.

The rear ground roller 8 of the implement is a so-called packer roller that is freely rotatable about its longitudinal axis a, the roller 8 comprising a circular cross-section cylinder 9 having an external diameter of substantially 30 cms. The outer surface of the cylinder 9 is furnished at regular intervals along its length with groups or crowns of plate-formation tinelike teeth 10, the general plane of each group of teeth 10 being substantially vertically perpendicular to the axis a. The teeth 10 are made in integral pairs and the shape of each such pair can be seen best in Figure 2 of the drawings from which it will also be apparent that each group of teeth 10 comprises a total of ten teeth and thus five integral pairs thereof.Each pair is welded to the outer surface of the cylinder 9 and it is noted that it is not essential that the teeth 10 should be formed in pairs nor that each group of teeth should comprise ten of them. Up to five teeth 10 may be formed integrally from a single sheet of plate-like material and be welded or otherwise rigidly secured to the outer surface of the cylinder 9. Generally speaking, the greater the number of teeth 10 in each integral assembly thereof, the smaller the number of welding operations that are required to secure all---of the teeth 10 to the outer surface of the cylinder 9 with corresponding reductions in assembly time, material used, and consequent production costs.

The teeth 10 in each group as illustrated in Figure 2 of the drawings are spaced apart from one another at regular 36 intervals around the axis a. Each tooth 10 has a rear edge, with respect to the intended direction of operative rotation (anti-clockwise, as seen in Figure 2) of the roller 8, that extends substantially radially with respect to the axis a and a leading compound-shaped edge of which a straight extension in said intended direction of operative rotation would be substantially tangential to the surface of the cylinder 9.This arrangement ensures that, when the teeth 10 bite into the ground surface during operative progress in the direction A, their substantially radially disposed edges offer a significantly greater resistance to progress through the soil than do their approximately S-shaped or compound-shaped edges with the result that the roller 8 tends to be continuously revolved at a steady speed that is proportional to the speed of travel in the direction A. The teeth 10 in each group may be turned angularly about the axis a relative to those in the or each neighbouring group.

There is a soil-shedding scraper 11 arranged to contact the external surface of the roller cylinder 9 between each successive ringshaped group of roller teeth 10, the scrapers 11 being themselves arranged in groups of five. Each scraper 11 is in the form of an oblong plate that is preferably, but not absolutely essentially, formed from spring steel.

Each scraper 11 is secured to a corresponding foot 12 by a bolt 1 5 whose shank extends through one of a pair of spaced slots 1 6 that both extend lengthwise of the corresponding scraper 11 mid-way across the width thereof.

The other slot 1 6 in the same scraper 11 receives a downwardly projecting pin 1 7 carried by the respective foot 1 2. This arrangement allows for lengthwise adjustment of each scraper 11, relative to the corresponding foot 12, to compensate for wear, and for the endfor-end reversal of each scraper 11 so that, once one scraping end thereof has been worn away to such an extent that no further adjust ment is possible, said scraper 11 can be temporarily removed from its foot 1 2 and be reversed in position so that the opposite end thereof can be substituted thus substantially doubling the life of each scraper 11 before eventual replacement can no longer be avoided.Each foot 1 2 is welded or otherwise rigidly secured to the lower end of a corresponding upright arm 1 3 of channel-shaped cross section, said arm 1 3 being disposed so that its web or base is foremost with respect to the direction A with its two limbs projecting rearwardly from the web or base in parallel relationship with one another and with the direction A. The feet 1 2 are secured to the lower ends of the arms 1 3 in such a way that, when the arms 1 3 are vertically disposed as shown in full lines in Figure 2 of the drawings the feet 1 2 extend obliquely downwardly and forwardly, with respect to the direction A, from their lower ends at a few degrees to the horizontal.Preferably, but not essentially, an angle of substantially 108 is enclosed between the longitudinal axis of each arm 1 3 and the general plane of the corresponding foot 12.

The upper ends of the webs or bases of five successively immediately neighbouring arms 1 3 are welded or otherwise rigidly secured to the rear of a corresponding adjusting plate 14 which plate 14 is provided, at its opposite ends, with corresponding pairs of upper and lower clamping shoes 21. A tubular carrier 20 of circular cross section rigidly interconnects two forwardly projecting support plates 22 that are parallel to one another and substantially parallel to the direction A, the leading ends of these support plates 22 being bolted to the short rear portion of the arms 5 by the same bolts 23 that couple those arm portions to the upper ends of the roller supports 6. The carrier 20 and its forwardly directed support plates 22 constitute a carrying frame for the successive groups of five scrapers 11.The adjusting plate 1 4 of each such group has the opposite screw-threaded ends of three relatively spaced U-bolts 1 8 entered through holes therein, said U-bolts 1 8 embracing the circular cross-section carrier 20 and their substantially horizontal shanks being provided with nuts 1 9 which can be tightened to clamp the adjusting plates 1 4 firmly to the carrier 20 or be loosened to allow the plates 14, and thus the corresponding arms 1 3 and scrapers 11, to be turned angularly about the longitudinal axis of the carrier 20.It will be noted from Figure 3 of the drawings that the holes in each plate 14 which receive the shanks of the corresponding U-bolts 18 also extend through the webs or bases, and thus between the rearwardly projecting limbs, of the arms 1 3 of the first, third and sixth arms 1 3 corresponding to each group of five scrapers 11 counting from either end of that group.

The circular cross-section carrier 20 extends substantially horizontally parallel to the axis of rotation a of the roller 8 at a level above that of the roller and substantially vertically above a rearmost region, with respect to the direction A, of the roller cylinder 9.

A lower rearmost end region of each support plate 22 is secured to the upper end of a corresponding downwardly and forwardly (with respect to the direction A) inclined arm 23A, the lower leading end of each such arm 23A being secured by a further bolt to one corner of the corresponding substantially square bearing housing 7 at the same axial end of the roller 8. The further bolts in question are, as can be seen in Figure 2 of the drawings, each one of a set of four which secures the corresponding bearing housing 7 to the lower rearmost end of one of the downwardly and rearwardly inclined supports 6.

When the scrapers 11 are to be adjusted for substantially optimum performance during the use of the implement, each group of five such scrapers 11 is dealt with by loosening the nuts 1 9 at the opposite ends of the three U-bolts 1 8 of the group so that the group, as a whole, can be turned angularly about the circular cross-section common carrier 20, the U-bolts 18 and shoes 21 acting as guides for such movements. Such guided movement is effected until, preferably, the leading and lower shorter edge of each oblong scraper 11 is just touching, or is very closely adjacent indeed to, the surface of the roller cylinder 9.

If necessary, at this time, any scraper 11 of the group of five that has its leading edge too far forwardly or too far rearwardly, may be adjusted in position relative to the corresponding foot 1 2 by loosening the corresponding bolt 1 5 and sliding said scraper 11 either rearwardly or forwardly employing the guide slots 16. Re-tightening of the bolt 1 5 concerned is all that is required to re-secure the adjusted scraper 11 relative to its carrying foot 1 2. Once the desired position of all five of the scrapers 11 of one of the groups relative to the surface of the roller cylinder 9 has been obtained, the nuts 1 9 are re-tightened to cause the U-bolts 1 8 and the clamping shoes 21 firmly to grip the common carrier 20.However, the nuts 1 9 are preferably only tightened to a predetermined extent using a torque-spanner or torque-wrench so that, as a result, each group of five scrapers 11 will normally maintain substantially the position shown in full lines in Figure 2 of the drawings in which the lower leading ends of its scrapers either just touch, or are very closely adjacent indeed to, the surface of the roller cylinder 9. If a stone, piece of wood or other hard object should become jammed between the teeth 10 of two neighbouring groups of those teeth, it will, as the roller 8 rotates in an anti-clockwise direction (as seen in Figure 2-of the drawings) about the axis a eventually meet the lower surface of the corresponding scraper 11.

A smooth and more or less spherical stone will tend to be dislodged from between the teeth 10 at either side of it by the scraper 11 concerned in the same way that said scraper 11 acts to shed mud, lumps of soil and the like from between the teeth 10 but a rough or jagged stone or rough piece of wood that is firmly jammed between the teeth 10 will, because of the continued rotation of the roller, exert an upwardly and rearwardly directed force against the lower surface of the scraper 11 which it meets, particularly if it catches against the corresponding bolt 1 5 and/or pin 1 7. The result is that a sufficient turning movement is exerted upon the complete group of five scrapers 11 to turn that group angularly about the common carrier 20 against the pre-set clamping force of the guiding U-bolts 18 and clamping shoes 21, the group turning rearwardly to a position such as the one shown in broken lines in Figure 2 of the drawings. This avoids the group of scrapers 11 being damaged by such a firmly jammed jagged stone, piece of wood or the like and, after manual removal of the offending object, the angularly displaced group of five scrapers 11 can be replaced into its effective position in the manner already described above. It will, of course, be realised that only rarely will jagged stones, pieces of wood and the like be met with, in previously employed agricultural land, that are of sufficient size to become firmly jammed between two neighbouring groups of the roller teeth 10.When the groups of scrapers 11 are being initially positioned, or are being repositioned, it is desirable to revolve the roller 8 about the axis a by hand so that a check can be made as to whether or not the clearance of the leading edges of the scrapers 11 relative to the roller cylinder 9 is substantially correct. As mentioned above, a nil clearance is ideal so that the roller 8 will still revolve readily whilst the scrapers 11 will perform an optimum soil-shedding function.

The opposite ends of the hollow frame portion 1 are provided, immediately beyond those ends, with corresponding shield plates 26 which shield plates extend substantially horizontally parallel to one another and to the direction A. Each shield plate 26 is carried by a corresponding arm which is turnable upwardly and downwardly about a portion of that arm which is journalled in brackets carried on top of the hollow frame portion 1 so as to define a substantially horizontal axis that is substantially parallel to the direction A. The lower ends of the shield plates 26 are shaped to slide forwardly over the ground surface in the direction A and their pivotal mountings enable them to move upwardly and downwardly, if required, to match undulations in the surface of the soil that are met with as the implement makes operative progress in the direction A.Each shield plate 26 co-operates with the immediately neighbouring rotary soil working member at one end of the row of the twelve such members in working the soil to substantially the same thorough extent as is produced by co-operation or neighbouring pairs of those members at locations closer to the centre of the implement. However, in addition, the shield plates 26 prevent the rapidly moving tines of the rotary soil working members from flinging stones and other hard objects laterally of the path of travel of the implement so that damage and injury attributable to this cause is very greately reduced, if not entirely eliminated. Each shaft 2 is provided, inside the hollow frame portion 1, with a corresponding straight- or spur-toothed pinion 27, the size of each pinion 27 being such that the twelve pinions 27 in the row have their teeth successively in mesh with one another.One of the centre pair of shafts 2 in the single row thereof has an upward extension through the top of the hollow frame portion 1 into a gear box 28 and bevel pinions and substantially horizontal shafts within the gear box 28 place the upward extension of said shaft 2 in driven connection with a rotary input shaft 30 of the gear box 28, the leading end of said input shaft 30 projecting forwardly in substantially the direction A from the front of the gear box and being splined or otherwise keyed to enable it to be placed in driven connection with a power take-off shaft at the rear of the agricultural tractor or other vehicle which moves and operates the implement by way of a known telescopic transmission shaft 31 having universal joints at its opposite ends.The rear of the gear box 28, with respect to the direction A, is provided with a change-speed gear 29 which is not illustrated in detail since its construction and operation are not the subject of the present invention. It suffices to say that the change-speed gear 29 has a removable cover beneath which the rearwardly projecting splined or otherwise keyed ends of two shafts can be interconnected by mounting the matchingly splined or otherwise keyed hubs of pairs of straight- or spur-toothed pinions of different sizes on those shaft ends. Each such pair of pin ions can be interchanged on the shaft ends, or be exchanged for an alternative pair of pinions, to give a chosen one of a number of different transmission ratios between the two shafts.Thus, the speed at which the twelve rotary soil working members will all revolve can be increased or decreased in response to a single more or less standard speed of rotation that is applied to the leading end of the rotary input shaft 30 of the gear 28 during the operation of the implement.

The chosen speed of rotation of the soil working members will depend upon the nature and condition of the soil that is to be cultivated and the particular purpose for which that soil is required after such cultivation.

The top and front of the frame portion 1, with respect to the direction A, is provided with a coupling member or trestle 32 that is of generally isosceles triangular configuration as seen in front or rear elevation. This coupling member or trestle 32 defines a pair of horizontally spaced apart lower coupling points and a single upper coupling point which may be employed in connecting the implement to the three-point lifting device or hitch of the same agricultural tractor or other vehicle that both moves and operates the implement in the use thereof. The three-point lifting device or hitch has an upper lifting link that is adjustable in length. Two steeply downwardly and rearwardly divergent tie beams strengtheningly connect substantially the apex of the coupling member or trestle 32 to widely spaced apart anchorages at the top and rear of the hollow frame portion 1.

In the use of the soil cultivating implement that has been described, its coupling member or trestle 32 is connected to the ends of the upper lifting link and lower lifting links of the three-point lifting device or hitch of the tractor or other vehicle which is to move and operate the implement and the telescopic transmission shaft 31 having universal joints at its opposite ends is used to place the rear power take-off shaft of the same tractor or vehicle in driving connection with the rotary input shaft 30 of the implement gear box 28.In addition to adjustment of the scrapers 11 that may possibly be required before work commences, it may also be necessary to adjust the changespeed gear 29 to increase or decrease the speed at which the soil working members will revolve and/or to change the maximum depth of penetration of the tines of those soil working members into the ground that is possible.

This latter adjustment is made by temporarily loosening the arresting clamps 25, operating the mechanisms 24 to raise or lower the bodily level of the roller 8 relative to that of the frame portion 1 and soil working members, and re-tightening the clamps 25. As the implement moves operatively in the direction A, each rotary soil working member, shaft 2 and pinion 27 will revolve in the opposite direction to the or each immediately neighbouring similar assembly due to the intermeshing arrangement of the pinions 27.Each rotary soil working member produces an individual strip of worked soil that extends in the direction A and the spacing between the tines of each soil working member is the same as, or a little greater than, the spacing between the axes of rotation of immediately neighbouring shafts 2 so that the strips worked by the individual members will successively overlap one another, or at least adjoin one another, to produce a single broad strip of worked soil that will have a width of substantially, but not necessarily exactly, 3 meters in the case of the example that is being described.It will be appreciated that smaller or larger working widths of the implement can be attained, without losing the advantageous spacing of substantially 25 cms between the longitudinal axes of neighbouring shafts 2, merely by increasing or decreasing the total number of those shafts 2 and, consequently, the total number of the rotary soil working members.

The groups or crowns of roller teeth 10 bite into the soil cultivated by the immediately preceding soil working members as the implement proceeds forwardly in the direction A and, due to the configuration of the teeth 10, as discussed above, the roller 8 revolved about the axis a at a uniform speed which is proportional to the speed of travel in the direction A. The roller cylinder 9 has a gentle compressing and consolidating effect upon the crumbled soil and assists in producing a seedbed of optimum characteristics for the germination of seeds and the subsequent onward growth of seedling plants.

As can be seen best in Figure 3 of the drawings, each scraper 11 extends throughout a major portion of the perpendicular distance between the two groups or crowns of teeth 10 by which it is flanked. The scrapers 11 very effectively shed mud and compacted soil from the roller 8 and it is noted that the general plane of each scraper 11 is, in the operative position of that scraper that is shown in full lines in Figure 2 of the drawings, inclined to an imaginary horizontal plane containing the axis of rotation a of the roller 8 at an angle that should not be less than 10 and which advantageously has a magnitude of substantially 30 . This arrangement causes the scrapers 11 to remove soil from between the groups or crowns of teeth in relatively small pieces rather than large lumps, these small pieces remaining within the sphere of effective action of the teeth 10 so that they can be crumbled thereby for useful addition to the seed bed that is being formed by the implement.

Substantially uniform wear of the five scra -pers 11 of one group can be compensated for by temporarily loosening the nuts 1 9 corresponding to that group and turning the whole group angularly about the common carrier 20 in a clockwise direction, as seen in Figure 2 of the drawings, through a small angle before retightening the nuts 1 9 to the desired extent preferably using, as discussed above, a torque spanner or torque wrench for this purpose.

Although convenient, it is not essential that the scrapers 11 should be arranged in groups and, if preferred, the arm 1 3 corresponding to each foot 1 2 and scraper 11 may be provided with an individual U-bolt 18, individual pair of nuts 1 9 and individual pair of upper and lower clamping shoes 21.As previously mentioned, once the leading lower edge of a scraper 11 has become worn to such an extent that re-positioning thereof relative to the corresponding foot 1 2 using the respective bolt 15, pin 1 7 and slots 1 6 is no longer possible. the bolt 1 5 concerned may be temporarily removed and the scraper 11 be re versed in position, end-for-end, so that the shorter edge thereof that was previously at the rear and upper end of the scraper becomes the fresh scraping edge at the lower leading end thereof. When, after extended use with appropriate adjustments in position, this edge, also, becomes so worn that no further adjustment is possible, the scraper 11 in question must be replaced by a new one.

The scrapers 11 can quickly and easily be brought to their optimum effective positions relative to the roller cylinder 9 in the manner that has been described above and that is illustrated in the accompanying drawings, particularly when said scrapers 11 are deployed in groups. The yieldability of the groups of scrapers 11, or of individual scrapers 11, about their common carrier 20 ensures that very rarely indeed, if ever, will jammed stones or other hard objects cause the scrapers 11 and/or their mountings to be damaged. Any scrapers 11 displaced by a jammed stone or other object can readily be restored to their operative positions.

Although certain features of the soil cultivating implement that have been described and/or that are illustrated in the accompanying drawings will be set forth in the following claims as inventive features, it is emphasized that the invention is not necessarily limited to those features and that it includes within its scope each of the parts of the soil cultivating implement that has been described, and/or that is illustrated in the accompanying drawings, both individually and in various combinations.

Claims (10)

1. A soil cultivating implement of the kind set forth, wherein said carrier is of circular or substantially circular cross-section and said arms are adjustably clamped to the carrier by means which is angularly displaceable around that carrier.

2. An implement as claimed in claim 1, wherein a plurality of said arms are united to form a group, said group being clamped to the carrier by at least two of said means.

3. An implement as claimed in claim 1 or 2, wherein a single carrying plate is provided for a plurality of said arms, and wherein a corresponding one of said means is provided at, or adjacent to, each end of the carrying plate.

4. An implement as claimed in any preceding claim, wherein each of said means affords a guide for the angular displaceability of said arms around the carrier.

5. An implement as claimed in claim 2 or claim 3, wherein said means includes screwthreaded nuts which are arranged so that they can be tightened to such an extent that angular displacement of the arms around said carrier during normal operation of the implement is prevented whereas a force of sufficient magnitude to prevent a threat of damage to at least one scraper and/or its mounting, when exerted upon said at least one scraper and/or its mounting, will overcome the clamping effect of said means and enable that means, together with at least one arm and said at least one scraper, to be displaced angularly around the carrier.

6. An implement as claimed in claim 5, wherein said means comprises U-bolts arranged around said carrier, the U-bolts having screw-threaded shanks with which said nuts co-operate.

7. An implement as claimed in claim 6, wherein the straight limbs of each U-bolt are horizontally or substantially horizontally disposed during normal operation of the implement.

8. An implement as claimed in any preceding claim, wherein each of said arms is vertically or substantially vertically disposed during normal operation of the implement, and wherein the lower end region of each arm carries a supporting foot for the corresponding scraper, the general plane of that foot being inclined to the longitudinal axis of the arm concerned at an angle of substantially 108 .

9. An implement as claimed in claim 8, wherein the construction of each scraper and of the corresponding supporting foot is such that said scraper can occupy either chosen one of two different effective scraping positions which are turned relative to one another through substantially 180 about the longitudinal axis of the corresponding arm.

10. A soil cultivating implement of the kind set forth, substantially as hereinbefore described with reference to the accompanying drawings.