GB2090712A - Soil cultivating equipment - Google Patents

Abstract

In a soil cultivating implement of the kind which comprises a row of rotary power driven soil working members 3, having tines 4, that is carried by a hollow elongate frame portion 1 that extends substantially horizontally perpendicular, or at least transverse, to the intended direction of operative travel A of the implement, screens 14 are arranged adjacent the opposite ends of the row of members 3 to co-operate with the nearest members 3 in cultivating the soil, said screens 14 taking the form of preferably resilient elongate elements 17 at least parts of which are non-horizontally disposed when the implement is in use. Advantageously, a carrier 15 of each screen 14 is connected to the hollow frame portion 1 so as to be upwardly and downwardly displaceable through the intermediary of an irregular quadrilateral linkage 16 comprising substantially horizontal pivots 11 and 13. <IMAGE>

Description

SPECIFICATION Soil cultivating implements This invention relates to soil cultivating implements or machines of the kind which comprise an elongate frame portion extending substantially horizontally perpendicular, or at least transverse, to the intended direction of operative travel of the implement or machine and carrying a plurality of soil working members that are rotatable about upwardly extending (non-horizontal) axes, an upright screen being provided at at least one end of the elongate frame portion which screen extends parallel or substantially parallel to said direction of operative travel and is arranged to co-operate with an adjacent one of said rotary soil working members in cultivating the soil.

The term "implement(s) or machine(s)" will be shortened to "implement(s)" alone throughout the remainder of this document for the sake of brevity.

The screens in known implements of the kind set forth are almost always of a solid formation in the nature of shield plates and are prone to be damaged by stones and other hard objects encountered during use. It is therefore an object of the present invention to reduce, if not completely eliminate, this disadvantage and, accordingly, one aspect of the invention provides a soil cultivating implement of the kind set forth, wherein the or each screen comprises a plurality of elongate elements at least parts of which are non-horizontally disposed when the implement is in operation.

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 shown connected to the rear of a n an agricultural tractor, Figure 2 is a side elevation, to a considerably enlarged scale, as seen in the direction indicated by an arrow II in Figure 1, Figure 3 is a front elevation of one side or end region of the implement as seen in the direction indicated by an arrow ill in Figure 2, Figure 4 is a view from the same standpoint and to the same scale as Figure 2 but illustrates an alternative embodiment, Figure 5 is a front elevation of one side or end region of the implement of Figure 4 as seen in the direction indicated by an arrowV in Figure 4, Figure 6 is an elevation from the same standpoint and to the same scale as Figures 2 and 4 but illustrates a third embodiment, and Figure 7 is a front elevation of one side or end region of the implement of Figure 6 as seen in the direction indicated by an arrow VII in Figure 6.

Referring firstly to Figures 1 to 3 of the accompanying drawings, the soil cultivating implement that is illustrated therein is in the nature of a rotary harrow and 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 1,2,4 and 6 of the drawings by an arrow A.A plurality, of which there are twelve in the example that is being described, of upwardly extending (non-horizontal) and usually vertically or substantially vertically disposed shafts 2 are rotatably journalled in bearings carried by the upper and lower walls of the frame portion 1 so as to lie in a single row in which the axes of rotation of the successive shafts 2 are spaced apart from one another at regular intervals which advantageously, but not essentially, have magnitudes of substantially 25 centimetres. The lowermost end of each shaft 2 projects downwardly from beneath the bottom of the hollow frame portion 1 and is there firmly but releasably provided with a corresponding rotary soil working member 3.Each member 3 has a diametrically opposed pair of cultivating members in the form of rigid tines 4 and the lowermost ends of the two tines 4 of each member are spaced apart from one another by a little greater distance than the spacing between the axes of rotation of immediately neighbouring shafts 2 so that, during operation, the strips of land which are worked by the individual members 3 will overlap one another to produce a single broad strip of worked soil which, in the case of the example that is being described, will have a width of substantially, but not necessarily exactly, 3 metres.

The opposite ends of the hollow frame portion 1 are closed by corresponding side plates 5 that are substantially vertically parallel to one another and usually parallel or substantially parallel to the direction A. The shapes of the plates 5 can be seen in Figure 2 of the drawings from which it will be apparent that each plate 5 has a greater vertical extent at the front thereof, with respect to the direction A, than it does at its rear. Each side plate 5 carries a corresponding strong substantially horizontal stub shaft 6 at a location which is just above the leading extremity, with respect to the direction A, of the hollow frame portion 1, the two stub shafts 6 being in axially aligned relationship.An arm 7 is turnable upwardly and downwardly about each stub shaft 6 and extends generally rearwardly with respect to the direction A from that stub shaft in closely adjacent relationship with the immediately neighbouring frame portion side plate 5. Rear regions of the two side plates 5 are formed with curved rows of holes 9 in which each hole 9 is at the same distance from the substantially horizontal axis defined by the aligned stub shafts 6 and each arm 7 is formed with at least one hole at the same distance from said axis so that, by turning the arms 7 upwardly and downwardly about the stub shafts 6, the hole, or at least one of the holes, can be brought into register with a chosen hole 9 in the immediately neighbouring side plate 5 whereupon a retaining bolt 8 can be entered through the registering holes to be subsequently tightened so that it will maintain the chosen angular position of the corresponding arm 7 about the axis defined by the aligned stub shafts 6 reliably and for as long as may be required.

The rearmost ends of the two arms 7 lie behind the row of soil working members 3 with respect to the direction A, being enlarged as compared with the remainders of the arms and being orientated obli quely downwardly and rearwardly. Substantially the lowermost extremities of these rearward portions of the two arms 7 carry substantially horizontally aligned bearings between which an open-work ground roller 10 of skeletal formation is mounted in afreely rotatable manner.The ground roller 10 comprises a central axially extending tubular shaft to which a plurality, such as five, of circular support plates are centrally secured at regularly spaced apart intervals, the skeletal curved ground-engaging surface of the roller 10 being afforded principally by a plurality, such as twelve, of tubular or rod-formation elongate elements which are entered lengthwise through substantially circumferential holes in the roller support plates so as, preferably and as shown in outline in Figure 1, to extend helically around the longitudinal axis of the roller in regularly spaced apart relationship from one another.The roller 10 provides a maximum depth control function for the tines 4 of the rotary soil working members 3 and serves, in its own right, as a soil working member to crush any lumps of soil exceptionally missed by the members 3 and to produce a gentle smoothing and levelling effect upon the surface of the ground that has immediately previously been dealt with by those members 3.

It can be seen in Figure 2 of the drawings that each frame portion side plate 5 has a leading edge which slopes downwardly and rearwardly, with respect to the direction A, away from the uppermost extremity thereof and that horizontal pivot pins 11 are carried by said plate 5 adjacent both the upper and lower leading corners of said plate 5. Upper and lower arms or links 12 have ends turnably connected to the corresponding side plate 5 by the upper and lower pivot pins 11 in a freely turnable manner and the opposite ends of the two arms or links 12 are turnably connected to a corresponding screen carrier 15 by respective horizontal pivots pins 13 which are parallel to the pivot pins 11.It will be realised that the two pivot pins 11 carried by the frame portion side plate 5 which is at the opposite end of said frame portion 1 to that which is visible in Figure 2 of the drawings are in substantially horizontal alignment with the two pivot pins 11 that can be seen in Figure 2 and that the parts 12, 13 and 15 which have just been described are symmetrically duplicated adjacent to the opposite end of the hollow frame portion 1. Each screen carrier 15 holds a corresponding screen 14 that extends generally rearwardly, with respect to the direction A, away from the leading carrier 15, each screen 14 also usually being directed obliquely downwardly and rearwardly when the implement is in operation (see the full line configuration that is illustrated in Figure 2).The leading screen 15 of each carrier 14 holds the corresponding pair of substantially horizontal pivot pins 13 and it will be noted that the perpendicular distance between those pivot pins 13 is less than is the perpendicular distance between the corresponding pair of pivot pins 11 mounted on the adjacent frame portion side plate 5. Advantageously, as shown, the distance between the pivot pins 13 is approximately half the distance between the pivot pins 11, the positions of the latter being such that a plane containing their two longitudinal axes is upwardly and forwardly inclined with respect to the direction A. The arms or links 12 are of the same length and it will be apparent from Figure 3 of the drawings that they are disposed inwardly of the corresponding screen carriers 15 at the sides thereof which face the centre of the implement.The pivot pins 11 and 13 afford substantially horizontal axes which are parallel to one another and substantially horizontally perpendicular, or at least transverse, to the direction A and they are located at the four corners of an irregular quadrilateral linkage 16, that is to say, a linkage which is not a parallelogram linkage and which has only two of its sides (afforded by the arms or links 12) of equal of substantially equal lengths.

The rear of each screen carrier 15 with respect to the direction A carries a plurality, such as five, of elongate elements 17 which are of strip formation.

The five, in this embodiment, elements 17 of each screen 14 extend parallel to one another in a vertical or substantially vertical plane and lie at regularly spaced apart distances from each other The five elements 17 are all straight and usually, when the implement is in operation, extend obliquely downwardly and rearwardly from the carrier 15 with respect to the direction A (see the position indicated in full lines in Figure 2). The leading end of each element 17 is firmly but releasably secured to the corresponding carrier 15 by a pair of spaced bolts and each element 17 is formed from a resilient material which is advantageously, but not essentially, spring steel. The broad flat sides of the elements 17 are all of elongate oblong shape (see Figure 2) and all five elements 17 of each shield 14 are of the same formation.As seen in side elevation (Figure 2), the rearmost ends of the elements 17, with respect to the direction A, are very close to the foremost region of the ground roller 10 with respect to the same direction.

Each rotary shaft 2 is provided, inside the hollow frame portion 1,with a corresponding straighttoothed or spur-toothed pinion 18 and the twelve pinions 18, in this embodiment, are of such sizes that each of them has its teeth in mesh with those of its immediate neighbour or both of its immediate neighbours so that, during operation, each pinion 18 in the single row or train thereof will revolve, together with the corresponding shaft 2 and soil working member 3, in the opposite direction to the or each immediately neighbouring similar assembly.

The opposite directions of rotation are indicated for two such assemblies by small arrows in Figure 1 of the drawings and it will be seen from Figure 3 thereof that the soil working members 3 are so positioned on the lowermost ends of the shafts 2 that, during operation, immediately neighbouring members 3 will not foul one another despite the fact that they are of greater working width than the spacing between the axes of rotation of immediately neighbouring shafts 2. One of the centre pair of twelve shafts 2, in this embodiment, has an upward extension through a top cover plate of the hollow frame portion 1 into a gear box 19 that incorporates, at its rear, a change-speed gear.It is not necessary to describe the construction of the gear box 19 and change-speed gear in any detail for the purposes of the present invention and it suffices to say that a chosen one of a number of pairs of intermeshing pinions of different sizes can be mounted in the change-speed gear for co-operation with the splined or otherwise keyed ends of a pair of substantially horizontal shafts to enable the rotary soil working members to be revolved at a faster or slower speed, as may be required, without having to change the initiating speed of rotation that is derived from the rear power take-off shaft of an agricultural tractor or other vehicle via a telescopic transmission shaft 20 (Figure 1) that is of a known construction having universal joints at its opposite ends.A central region of the front of the hollow frame portion 1, with respect to the direction A, is provided with a coupling member or trestle 21 that is of substantially triangular configuration as seen in front or rear elevation. This coupling member or trestle 21 is constructed and arranged to enable the implement to be connected to the three-point lifting device or hitch at the rear of an agricultural tractor or other operating vehicle in a manner that is shown in outline in Figure 1 of the drawings. The top and rear of the coupling member or trestle 21 is connected to the top and rear of the hollow frame portion 1 by a pair of steeply divergent downwardly extending tie beams.

In the use of the soil cultivating implement that has been described with reference to Figures 1 to 3 of the drawings, the implement is connected by the coupling member or trestle 21 to the three-point lifting device or hitch at the rear of an agricultural tractor or other operating vehicle in the manner that is shown in outline in Figure 1 of the drawings and a forwardly projecting substantially horizontal rotary input shaft of the gear box 19 is placed in driven connection with the rear power take-off shaft of the same tractor or other vehicle by way of the known telescopic transmission shaft 20 that has universal joints at its opposite ends.The change-speed gear at the rear of the gear box 19 is adjusted, if necessary, to give a speed of rotation of the soil working members 3 which is appropriate to the nature and condition of the land that is to be worked and to the depth of cultivation that is required. The maximum depth of penetration of the tines 4 of the soil working members 3 into the soil that is possible is adjusted, again if required, by temporarily removing the retaining bolts 8 and turning the arms 7 upwardly or downwardly about the strong stub shafts 6 to bring fresh holes in those arms into register with appropriate holes 9 in the frame portion side plates 5.The retaining bolts 8 are then replaced and tightened to dictate the level of the axis of rotation of the ground roller 10 relative to that of the frame portion 1 and thus, to a large extent, the greatest depth into the soil to which the tines 4 can penetrate.

As the implement moves in the direction A over land which is to be cultivated, the drive from the rotary input shaft of the gear box 19 is transmitted to the twelve, in this embodiment, rotary soil working members 3 via the upward extension of the shaft 2 which corresponds to a substantially central one of them and all of the members 3 revolve in directions which are opposite to the directions of rotation of their immediate neighbour or neighbours. As mentioned above, the twelve members 3 work individual strips of land which overlap one another to produce a single broad strip of worked soil having a width of substantially 3 metres in the case of the example that is being described.The members 3 at the opposite ends of the single row thereof co-operate with the respectively neighbouring screens 14 in crumbling and distributing soil displaced by the tines 4 in substantially the same way as occurs by the cooperation of immediately neighbouring pairs of members 3 at locations closer to the centre of the implement. The screens 4 also prevent significant ridging at the opposite margins of the broad strip of worked soil and guard against stones and other hard objects of any significant size being flung laterally of the path of travel of the implement so that the danger of injury or damage to persons, livestock and property from this cause is very greatly reduced, if not completely eliminated.The resilient elongate elements 17 of each screen 14 extend downwardly and rearwardly from their respective carriers 15 in dependence upon the maximum working depth of the soil working members 3 that has been pre-set by the positions of the arms 7 and, whilst said elements 17 have sufficient rigidity and resistance to provide the necessary counter-pressure for co-operation with the tines 4 of the neighbouring soil working members 3 to produce the required soil-crumbling and soil-distributing effect, their resiliency is none the less sufficient to enable them to flex outwardly when required to allow a momentarily trapped stone or other hard object of significant size to be released without damage to the implement and without any noticeable interruption in the cultivating operation.

As soon as such a momentarily trapped obstacle is released, the resilient elements 17 revert to their initial undeflected configurations. Where the neighbouring tines 4 move generally rearwardly with respect to the direction A alongside the elements 17, any mud, tangled grass or other adhering material tends to be moved lengthwise along said elements for eventual release at the rearmost ends thereof.

The relatively spaced arrangement of the elongate elements 17 allows the whole of each screen 14 to have a weight which will generally be less than that of a solid screen or shield plate of similar extent without, however, any reduction in efficiency.

If the leading end of one of the screens 14 should strike an obstacle, such as a stone embedded in the soil the whole screen can tilt upwardly as shown in broken lines in Figure 2, and to some extent rearwardly, in a very rapid manner by deflection of the corresponding irregular quadrilateral linkage 16.

In particular, the rear of the screen 14 will move upwardly more rapidly than the front thereof to protect the elements 17 from being bent, broken or otherwise damaged by the obstacle. However, the extent of the deflection is not usually so great that the co-operation between the tines 4 of the immediately neighbouring soil working member 3 and the elongate elements 17 of the deflected screen 14 is completely lost. In any case, as soon as the obstacle has been passed by continued movement in the direction A, gravity immediately causes the deflected screen 14to drop back into substantially the position which it occupied relative to the remainder ofthe implement prior to meeting said obstacle.

Figures 4 and 5 of the drawings illustrate an embodiment in which the frame portion side plates 5 of the first embodiment are replaced by frame portion side plates 22 having a different shape. A front region of each side plate 22 projects forwardly of the frame portion 1 by a considerable distance in substantially the direction A and each such front region carries a corresponding substantially horizontally disposed pivot pin 23 about which a corresponding screen 24 is freely upwardly and down wardlyturnable. Each screen 24 co-operates with the tines 4 of the immediately neighbouring rotary soil working member 3 in cultivating the soil, extends generally in the intended direction of operative travel A of the implement and is disposed in a upright position.The leading upper end of each screen 24, with respect to the direction A, comprises a substantially trapezoidal carrier 25, pivotally mounted on the associated pivot pin 23, the "base" edge of each carrier 25 being upwardly and rearwardly inclined from its lower end at an angle of substantially 45" to the horizontal (see Figure 4).

Each carrier 25 supports two pairs of resilient elongate elements 26, the two elements 26 of each pair being integral with one another and having a basically "hairpin" shape with the 180 bend that integrally interconnects the two elements 26 being releasably clamped against the outer surface of the corresponding carrier 25 by a shaped clamping plate 27 that is fastened in its operative position by a corresponding bolt 28.It will be seen from Figure 4 of the drawings that the arrangement of the two pairs of elements 26 is such that the four elements are regularly spaced part from one another and initially project downwardly and rearwardly from the carrier 25 concerned at angles of substantially 45 to the horizontal afterwhich they merge by way of shallow bends into straight rearwardly directed portions that are substantially horizontal when the implement is in use. The rearmost ends of the four elements 26 of each screen 24 are located, as seen in Figure 4 of the drawings, a very short distance in front of a foremost region of the ground roller 10.

The two elements 26 of each pair are preferably, but not essentially, formed from a single length of spring steel rod of circular cross-section. When the implement of Figures 4 and 5 of the drawings is in use, the two screens 24 at the opposite ends of the hollow frame portion 1 co-operate with the immediately neighbouring rotary soil working members 3 in cultivating the soil in much the same way as has already been described with reference to Figures 1 to 3 of the drawings but, in this case, the elements 26 are resiliently deflectable in all directions whilst the weight of each screen 24 may be very dramatically reduced as compared with a solid screen in the form of, for example, an upwardly and downwardly displaceable shield plate.Whilst, in view of the resilient deflectability of the elements 26, upward and downward displacement of each screen 24 about a single substantially horizontal axis (afforded by the corresponding pivot pin 23) will usually suffice, it will be appreciated that the screens 24 may be connected to the side plates 22 by irregular quadrilateral linkages substantially corresponding to the linkages 16 that have been described above if that is considered to be preferable.

Figures 6 and 7 of the drawings illustrate a further alternative embodiment in which, once again, the frame portion side plates 5 of Figures 1 to 3 of the drawings are replaced by frame portion side plates 29 that are of a different shape and which project considerably further above the top of the frame portion 1 than do the side plates 5 or the side plates 22 of the embodiment of Figures 3 and 4. In the embodiment of Figures 6 and 7 of the drawings, each side plate 29 has a corresponding screen 30 displaceably connected to it which screen 30 is again of upright configuration and is disposed so as to extend parallel or substantially parallel to the direction A.Each screen 30 comprises a carrier 33 formed with two oblique slots 32 which are spaced apart from one another in the direction A, each slot 32 being upwardly and forwardly inclined from its lower end, with respect to the direction A, at an angle of substantially 75 to the horizontal. Retaining bolts 31 are entered through the slots 32 and through registering holes in the adjoining side plate 29 and it will be apparent that the screens 30 are upwardly and downwardly adjustable in position relative to the corresponding side plates 29 merely by temporarily loosening the bolts 31, sliding the carriers 33 of said screens 30 upwardly or downwardly, as may be required, to fresh positions and re-tightening the bolts 31 to maintain those positions as long as may be required.

Each screen 30 comprises a plurality, such as nine, of elongate elements 34 in the form of resilient strips which may advantageously, but not essentially, be formed from spring steel. The upper end of each strip 34 is firmly but releasably secured to the corresponding carrier 33 by a pair of obliquely spaced apart bolts and it will be seen that each strip 34 extends parallel to the two slots 32 and to each of its companions that are regularly spaced apart from one another in substantially the direction A. The upper and lower extremities of the elements 34 are bevel cut so that the lowermost ends will all coincide with, or be very close to, a straight line that extends substantially horizontally parallel to the direction A when the implement is in use despite the upwardly and forwardly disposed orientation of the strips 34 themselves. Once again, as seen in side elevation (Figure 6), the rearmost extremity of each screen 30, with respect to the direction A, is located very closely in front of a leading region of the ground roller 10.

When the implement of Figures 6 and 7 of the drawings is being prepared for use, it is necessary to adjust the horizontal levels of the two screens 30, in the manner described above, to match the maximum depth setting of the tines 4 of the soil working members 3 which has been adopted since the screens 30 are not automatically upwardly and downwardly displaceable relative to the side plates 29. Despite the resilient formation of the elongate elements 34, they are of sufficient strength to provide the required counterpressure for soil cultivating co-operation with the tines 4 of the immediately neighbouring rotary members 3 when the implement is is operation so that soil crumbled between each screen 30 and the neighbouring member 3 is adequately cultivated and is spread uniformly rearwards for final treatment by the ground roller 10.The downward and rearward orientation of each element 34 tends to ensure that any adhering material such as soil, elongate stem debris and the like will be conducted rearwardly and downwardly along the elements 34 for eventual release at the lowermost ends thereof. If one of the screens 30 should meet a large stone, old root or other embedded obstacle, the resilient formation of its elements 34 will enable those elements to deflect sufficientlyfarto avoid being damaged by the obstacle and with only a momentary interruption, if any, to the cultivating action in the affected region of the implement. The resiliently deflected elements 34 will, of course, immediately revert to their original positions once the obstacle has been passed.

Although certain features of the soil cultivating implement embodiments 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 emphasised that the invention is not necessarily limited to those features and that it includes within its scope each part of each of the embodiments that has been described and/or that is illustrated in the accompanying drawings both individually and in various combinations.

Claims (14)

1. Asoil cultivating implementofthe kind set forth, wherein the or each screen comprises a plurality of elongate elements at least parts of which are non-horizontally disposed when the implement is in operation.

2. An implement as claimed in claim 1, wherein the or each screen is upwardly and downwardly displaceable relative to said frame portion through the intermediary of an irregular quadrilateral linkage whose pivotal axes are horizontally or substantially horizontally disposed.

3. A soil cultivating implement of the kind set forth, wherein the or each screen is upwardly and downwardly displaceable relative to said frame portion through the intermediary of an irregular quadrilateral linkage whose pivotal axes are horizontally or substantially horizontally disposed.

4. An implement as claimed in any preceding claim, wherein at least parts of the elongate elements of the or each screen are upwardly and forwardly inclined with respect to the direction of travel of the implement when that implement is in operation.

5. An implement as claimed in any preceding claim, wherein parts of the elongate elements of the or each screen are horizontally or substantially horizontally disposed when the implement is in operation.

6. An implement as claimed in any preceding claim, wherein each elongate element is eonnected to the remainder of the implement only at one end of that element.

7. An implement as claimed in claim 6, wherein each element is of rectilinear configuration from its free end throughout all or part of its length.

8. An implement as claimed in claim 7, wherein the elongate elements, or at least the rectilinear portions thereof, are inclined to a flat horizontal ground surface at an angle of substantially 75 .

9. An implement as claimed in claim 6 when read as appendantto claim 5, wherein, during the operation of the implement, the elongate elements extend substantially horizontally away from their free ends and then merge into upwardly directed portions by way of shallow bends.

10. An implement as claimed in claim 2 or claim 3 or in any one of claims 4 to 9 when read as appendant to either claim 2 or claim 3, wherein the or each irregular quadrilateral linkage comprises a pair of arms or links disposed one above the other, said arms or links being turnable relative to the frame portion about corresponding horizontal or substantially horizontal axes.

11. An implement as claimed in claim 10, wherein the spacing between the ends of the arms or links which are pivotally connected to said frame portion is greater than the spacing between the ends of the arms or links that are pivotally connected to the screen or corresponding screen.

12. An implement as claimed in claim 11,where- in the distance between the pivotal connections of said arms or links to the frame portion is substantially twice the distance between the pivotal connections of said arms or links to the screen or corresponding screen.

13. An implement as claimed in any one of claims 10 to 12, wherein the pivotal connection of the upper arm or link of the or each irregular quadrilateral linkage to said frame portion is in advance of the pivotal connection of the lower link of the same irregular quadrilateral linkage to that frame portion with respect to the intended direction of operative travel of the implement.

14. A soil cultivating implement of the kind set forth substantially as hereinbefore described with reference to Figures 1 to 3 or with reference to Figures 4 and 5 or Figures 6 and 7 of the accompanying drawings.