DRIVE LINKAGE FOR AGRICULTURAL DEVICE

Abstract: A mechanical linkage arrangement which can be used in an agricultural device like a soil agitator, a turf cutter or a turf aerator to impart motion from a drive means (65) to a reciprocable member (75) such as a cutting blade (76), is arranged such that if the drive means (65) is driven at a constant velocity, the velocity of the reciprocable member (75) varies and is a maximum about one extreme of its path of reciprocation. The arrangement may comprise a plurality of sequentially connected linkages (300, 301, 302, 303) including a first linkage (300) connected to the drive means (304) and a final linkage (303) connected to a reciprocable member, each subsequent linkage describing a reciprocating path in response to reciprocating motion of the preceding linkage. Each linkage is connected to respective supporting linkages (309, 310, 311) by connecting rods (312, 313, 314), the supporting linkages being mounted on a frame whereby to constrain the motions of the respective linkages within their respective reciprocating paths. In an arrangement having n linkages, for a single reciprocation of the first linkage the final linkage is driven through 2(<n-1>)reciprocations.

Description: DRIVE LINKAGE FOR AGRICULTURAL DEVICE The present invention relates to an improved drive linkage, and, in particular, to an improved drive linkage for an agricultural device, such as the type of 5 agricultural device used for soil agitation, turf aeration and turf cutting. Soil agitation devices are known and are intended to be used primarily in caring for turfed areas, such as the greens and fairways of golf courses, for example, although 10 they may be used in other more general agricultural applications. A soil agitation device generally includes a plurality of vertically spaced apart vertically orientated thin blades mounted to a frame and arranged to cut channels in surface soil and to break up soil 15 compaction as the device is moved along. The manner in which the blades are driven through the soil is of prime importance to the efficient functioning of the device. Turf aeration devices are known for providing small holes in surface turf, such as sports fields, for example, 20 in order to allow air to circulate within the turf and to promote healthy growth. One such device (see our Australian Patent No. 572915) includes a plurality of elongate rods mounted for vertical reciprocation on a frame, such that, during the reciprocation, each rod makes 25 a hole in the turf. As the device frame is moved along, therefore, a plurality of holes will be made in the turf to provide aeration. The way the rods are driven is very important to the efficient functioning of the device. A turf cutting device uses an elongate blade 30 travelling substantially parallel with the ground at turf depth in order to cut underneath the turf. The blade is supported at either end by two substantially vertical arms which are pivoted at their other ends to allow the blade to be moved backwards and forwards in a rocking motion to 35 chop into the turf. Motion is imparted to the vertical arms by a cam drive arrangement. SUBSTITUTE SHEET There are a number of prior art soil agitation devices, which each use different drives for the blades. In one prior art machine, the plurality of blades are resiliently mounted adjacent to each other and spaced apart by the distance required for the width of the parallel channels in the soil. A cylindrical bearing, driven by drive means about an axis offset from the central axis of the cylinder is arranged to transfer its eccentric motion to the blades via an elongate beam to cause the blades to move forwards and backwards in a rapidly oscillating manner as the machine is moved along the surϊace. In another prior art machine, an eccentric weight is mounted on the machine and is caused to rotate by drive means, the motion causing the whole machine to vibrate and thus causing the blades to resonate as they are pulled through the soil. Vibration of the parallel blades, whether forward and backward vibration, as in the first prior art example, or by resonation, as in the second prior art example, enables the blades to be pulled through the soil with less effort than if they were stationery relative to the machine and causes some decompaction of the soil adjacent to the blades. A further prior art machine drives the blades to move in an out of phase manner with respect to each other. Each blade is separately driven by an associated cylindrical bearing which is mounted eccentrically. Each cylindrical bearing is offset in its rotary action with respect to each other cylindrical bearing, so that each respective blade is impelled forwards at a different time. This "staggered" motion of the blades results in a reduction of shock vibration of the mounting frame. However, this machine and the other prior art machines discussed above, tend to tear any turf or crop rather than SUBSTITUTE M ET cutting cleanly through it. This is undesirable, particularly where the machine is being used to care for greens and sports fields. Greencare Pty Ltd had previously developed a soil agitation device which comprises a frame arranged to be towed or self-propelled and mounting at least one cutting blade arranged to penetrate the soil vertically and cut a channel therein as the frame moves along, the blade being mounted for reciprocating motion relative to the frame along a line coincident with the direction of cutting. In this device, each blade is mounted at the end of an arm mounted for pivotal movement to allow reciprocation of the blade through the soil. The arms are driven by means of a camshaft which mounts a plurality of cams, one for each arm. Corresponding cam followers are mounted on each arm and when the camshaft turns the cam follower contacts its respective cam and follows the cam profile to cause the arm to pivot and the blade to reciprocate.On the opposite side of each arm from the cam a resilient means is provided to bias the arm towards the cam. The present invention provides an alternative mechanical drive linkage which can advantageously be used to provide the required pivoting of the arm of a soil agitator and the correct reciprocation of the blades. The inventive drive linkage may also be adapted to drive the tyne arms in a turf aerator, such as the turf aerator disclosed in our Australian Patent No. 572915, and also to drive the substantially vertical arms in a turf cutter. In general, the inventive mechanical linkage could be used to drive any member which it is desired to drive in a reciprocating fashion. The present invention provides a substantially reciprocal implement connected by a plurality of linkages to a drive means, actuation of said drive means causing reciprocation of said implement. SUBSTITUTESHEET Said plurality of linkages preferably includes a first linkage which is connected to said drive means and describes a linear path in response to said drive means, and a second linkage describing a reciprocating path in response to the motion of said first linkage, and connected to said reciprocating member. Said drive means is preferably a means for converting a rotational motion into a substantially linear motion and preferably includes a member arranged to describe an orbital path and connected to drive said first linkage along said linear path in response to said orbital motion. Said drive means is preferably a rotational eccentric which is connected to said first linkage by a connecting rod. Said linkages are preferably arranged such that a second linkage connected to the reciprocating element carries out a plurality of reciprocations in response to a single traverse of a first path by a first linkage. Preferably, said linkages are arranged such that the velocity of reciprocation varies along the path of reciprocation, and preferably the velocity is at a maximum about one extreme of the reciprocation. The present invention further provides a mechanical linkage arrangement, for connecting a reciprocable member to a drive means and for driving the reciprocable member in a reciprocating fashion in response to actuation of the drive means, the mechanical linkage arrangement being arranged to impart motion to the reciprocable member such that if the drive means is travelling at a substantially constant velocity magnitude the magnitude of the velocity of the reciprocable member varies along its path of reciprocation and is a maximum about one extreme of the reciprocation. The linkage arrangement preferably comprises a plurality of sequentially connected linkages, including a SUBSTITUTE SHEET final linkage connected to the reciprocable member and a first linkage connected to the drive means. The linkages are preferably connected to each other and to the drive means by substantially rigid connecting members, such as connecting rods, for example. The linkages are also preferably supported and constrained within reciprocating paths of motion by supporting linkages mounted on a frame (i.e. where the drive is being used in an agricultural device, the frame of the device) and connected to the respective linkages by further connecting rods. there are preferably at least two linkages, being the first and final linkage, but there may be any number of linkages connected sequentially between the first and the final linkage. The linkage arrangement is preferably such that the final linkage carries out a plurality of traversals of its reciprocating path for each single traversal of the reciprocating path of the first linkage. Where there are n linkages, for each single reciprocation of the first linkage, the nth linkage will preferably make 2^ " ' traversals. The reciprocating paths of adjacent linkages in the sequence are preferably substantially perpendicular to each other. The drive means preferably comprises a drive member arranged to describe an orbital path, preferably a rotatable eccentric mounted on a drive shaft. The linkage arrangement is preferably utilised in an agricultural device, such as a soil agitator, turf cutter or turf aerater. The linkage of the present invention has a number of advantages in applications requiring reciprocation of an implement, such as the blade arm of a soil agitator or the tynes of a turf aerator, or the blade arms of a SUBSTITUTESHEET turfcutter. The linkage of the present invention is useful for all these applications. Where the drive means is an orbital member connected to the first linkage and the linkages are arranged such that the final linkage traverses the reciprocating path a plurality of times for a single traverse of the first path by the first linkage, a first advantage arises in the fact that the reciprocating member preferably travels through two reciprocations for one traverse of the orbit. The drive means preferably comprises an eccentric mounted on a drive shaft for rotation, the drive shaft extending from a gear box. This two reciprocation per single turn feature means that the member is reciprocated with substantial velocity and great efficiency. Secondly, because the reciprocating member is connected directly to the drive means by a linkage the member is "power driven" throughout its reciprocating cycle. There is no reliance on a resilient means such as a spring to cause any motion of the reciprocating member. The member is driven throughout the whole extent of reciprocation by the linkage. This results in a great reduction of noise and increase in efficiency over an arrangement, such as Greencare's earlier arrangement, where rotating cams and cam follower arrangements act to power the reciprocating arm of the soil agitation device. Thirdly, the linkages are preferably arranged such that the reciprocating member reaches its maximum velocity in an area about the outer most extent of its reciprocation. That is, where this invention is applied to drive the blade of a soil agitator, for example the blade will reach its maximum velocity as it cuts into the soil at the outer most extent of its reciprocation, and as it is pulled back from the soil just past the outer most extent of its reciprocation. In other words, "fast attack" and "fast drop off" are applied to the blade, SUBSTITUTE SHEET resulting in efficient cutting of soil without tearing of any turf and increased shock to the soil causing shattering and loosening of packed earth. Similarly, where the inventive linkage is applied to drive a tyne arm of a turf aerator, the maximum velocity will be reached as the tyne is about its outer-most extension, meaning that the tyne will be pushed very quickly in and out of the ground as the turf aerator is moved along, again preventing undue tearing of any turf. Similarly for the blade of a turf cutter. A further advantage allied to the above feature is that of "fast turnaround" of the reciprocating member at one extreme of its motion. The linkages are preferably arranged such that when the reciprocating member reaches one extreme of its motion it remains stationary at the extreme for a minimum amount of time before commencing its return stroke at maximum velocity. Where the drive means includes a member arranged to describe an orbital path these "fast turnaround", "fast attack" and "fast drop off" features can be achieved by arranging the linkages such that at the one extreme of the reciprocation the orbital angular motion of the member is being converted into maximum traverse of linear motion. In a preferred embodiment, where the mechanical linkage arrangement comprises only a first and final linkage in the sequence, this maximum velocity of the reciprocating member about the outer most extension of the reciprocation is preferably provided by the arrangement of linkages such that, when the first linkage is half way through the first path of motion the second linkage is at the outer most extreme of the second path of motion, and the drive means is applying force such that the first linkage is at its maximum velocity at the centre of its first path. The second and first paths of motion are preferably substantially perpendicular to each other. SUBSTITUTESHEET An advantage of the ability to turn a single reciprocation of the first linkage into a 2^ n" ) reciprocations of the final linkage is that for a slow drive means an extremely rapid, as rapid as desired, reciprocation of the final linkage can be obtained. In the preferred embodiment, the "throw" or length of path of each reciprocation for each linkage decreases as one goes along the sequence away from the first linkage. The present invention provides from a further aspect, a mechanical linkage arrangement, for connecting a reciprocable member to a drive means and for driving the reciprocable member in a reciprocating fashion in response to actuation of the drive means, the mechanical linkage arrangement comprising a plurality of sequentially connected linkages, including at least a first linkage connected to the drive means and at least a final linkage connected to the reciprocable member, each subsequent linkage in the sequence being arranged to describe a reciprocating path in response to reciprocating motion of the preceding linkage and wherein, in an arrangement having n linkages, for a single reciprocation of the first linkage the final linkage is driven through 2^ n ~ ' reciprocations. The present invention provides, from yet a further aspect, a mechanical linkage arrangement, comprising a drive means for driving a reciprocable member in a reciprocating fashion and a linkage arrangement connecting the drive means to the reciprocable member, the drive means comprising a rotatable eccentric mounted on a drive shaft, and the linkage arrangement comprising a plurality sequentially connected linkages, being connected by connecting rods, and being at least a first linkage connected to the eccentric by a connecting rod and at least a final linkage connected to the reciprocable member, each subsequent linkage in the sequence being SUBSTITUTESHEET arranged to describe a reciprocating path in response to reciprocating motion of the preceding linkage, each linkage in the sequence, apart from the final linkage, being connected to respective supporting linkages by connecting rods, the respective supporting linkages being mounted on a frame, whereby to constrain the motions of the respective sequentially connected linkages within their respective reciprocating paths. From yet a further aspect the present invention provides a device for agitating soil, comprising a frame arranged to be towed, pushed or self-propelled and mounting at least one cutting blade arranged to penetrate the soil and cut a channel therein as the frame moves along, the blade being mounted for reciprocating motion along a line coincident with the direction of cutting, and drive means for providing drive for causing reciprocating motion of the cutting blade, and a mechanical linkage for causing reciprocating motion of the cutting blade, the mechanical linkage including any or all of the features of the mechanical linkage discussed above. In a preferred embodiment, the mechanical linkage includes only a first and final linkage, the first linkage being connected to the drive means by a rigid connecting member and the final linkage being connected to a pivotable arm mounting the cutting blade. Preferably, the linkage is arranged to impart motion to the cutting blade such that the maximum velocity magnitude of motion occurs about the forwardmost extent of reciprocation of the blade giving rise to the advantages of "fast turnaround", "fast attack" and fast drop off" as discussed above. The device preferably mounts a plurality of blades and a plurality of reciprocating pivoted arms, there being provided a plurality of respective mechanical linkages connected to eccentrics mounted for rotation by a drive SUBSTITUTESHEET shaft in order to reciprocate the arms. The eccentrics are preferably arranged such that motion of the arms is staggered so that their relative motions are out of phase with each other. Preferably, the staggering is arranged so that a minimum number of blades are travelling forwards and cutting into the earth at the same time. From yet a further aspect, the present invention provides an aerating machine for turf, comprising a frame arranged to be towed, pushed or self-propelled and mounting a plurality of rigid tyne arms arranged for reciprocation such that a tyne at the end of each tyne arm is arranged to pierce the turf as the machine moves along, a drive means for providing drive for causing reciprocation of the tyne arms, and a mechanical linkage arrangement for connecting the drive means to each tyne arm, the mechanical linkage including any or all of the features of the mechanical linkage discussed above. In a preferred embodiment, the mechanical linkage includes only a first and final linkage, the first linkage being connected to the drive means by a rigid connecting member and the final linkage being connected to the tyne arm mounting the tyne. Preferably, the linkage is arranged to impart motion to the tyne arm such that the maximum velocity magnitude of motion occurs about the forwardmost extent of reciprocation of the tyne giving rise to the advantages of "fast turnaround", "fast attack" and "fast drop off" as discussed above. A plurality of linkages are preferably provided, one for each tyne arm. Said drive means preferably includes a rotatable eccentric in each case, the eccentrics being mounted on the drive shaft in a staggered fashion, so that respective tynes enter and leave the turf in a staggered manner. From yet a further aspect, the present invention SUBSTITUTESHEET provides a turf cutting device, comprising a frame arranged to be towed, pushed or self-propelled and mounting a turf cutting blade arranged to penetrate the turf and extending substantially horizontally between a pair of supporting arms mounted to the frame for reciprocation, drive means for providing drive for causing reciprocating motion of the arms, and a mechanical linkage arrangement connecting the drive means to each arm, the mechanical linkage arrangements including any or all of the features of the mechanical linkage discussed above. In a preferred embodiment, each mechanical linkage includes " only a first and final linkage, the first linkage being connected to the drive means by a rigid connecting member and the final linkage being connected to the respective supporting arm. Preferably, the linkage is arranged to impart motion to the cutting blade such that the maximum velocity magnitude of motion occurs about the forwardmost extent of reciprocation of the blade giving rise to the advantages of "fast turnaround", "fast attack" and "fast drop off", as discussed above. The drive means preferably includes an eccentric mounted on a drive shaft, one eccentric for each linkage, the eccentrics rotating synchronously so as to propel the respective supporting arms through their respective reciprocating paths in synchronism. Features and advantages of the present invention will become apparent from the following description of embodiments thereof, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a schematic front on view of a surface soil agitating device in accordance with an embodiment of the invention; Figure 2 is a schematic top plan view of the agitating device of Figure 1; SUBSTITUTESHEET Figure 3 is a schematic bottom plan view of the agitating device of Figure 1; Figure 4 is a side cross sectional view of the agitating device of Figure 1 along 1 in x-x of Figure 2; Figure 5 is a perspective view from the side illustrating in detail a mechanical drive linkage in accordance with an embodiment of the present invention connected to drive one of the blades of a soil agitating device such as illustrated in the preceding figures; Figure 6 is a schematic top plan view of a stabiliser arrangement for an arm supporting a cutting blade on a soil agitating device such as illustrated in the preceding figures; Figure 7 is a schematic side on view of a mechanical drive in accordance with the present invention driving the blade leg of a soil agitating device, for the purposes of explaining the operation of the drive; Figure 8 is a schematic view of a mechanical linkage in accordance with the present invention which incorporates four linkages; Figure 9 is a front view of a turf aerator in accordance with an embodiment of the invention disclosed in our Australian patent No. 572915, showing, for clarity, only two tyne arms; Figure 10 is a schematic side view of the turf aerator shown in Figure 9; Figure 11 is a side detailed view of a portion of the aerator shown in Figures 9 and 10; Figure 12 is a schematic side view of a turf cutter in accordance with an embodiment of the present invention; and Figure 13 is a schematic front view of a turf cutter in accordance with an embodiment of the present invention showing just the top of the frame and the arms supporting the turf cutting blade. Figure 14 is a detailed view of the roller mount and roller for the soil agitator of Figure 1. SUBSTITUTESHEET With reference to Figures 1 to 4, a soil agitating device in accordance with an embodiment of the invention will be described. The device, generally designated by reference numeral 1, comprises a metal frame 2, preferably steel, which mounts a plurality of reciprocal cutting blades 3 which are arranged to penetrate the soil as the device 1 is moved along the ground, causing decompaction of the soil by virtue of their reciprocating action and also acting to cut drainage channels in the soil. The reciprocating blades 3 are driven by drive means 4 and drive shaft 5 which mounts a plurality of staggered eccentrics 6, one for each cutting blade 3. Each drive eccentric 6 is connected to its respective cutting blade 3 by a mechanical linkage in accordance with an embodiment of the present invention, which will be described in more detail later with reference to Figure 5. The mechanical linkage and eccentric 6 drive are arranged to drive the cutting blades 3 so that they reciprocate in a staggered manner. If a "still picture" of the reciprocating blades 3 was taken at any time, the blades would not be parallel to each other but will be at different positions in their respective reciprocating actions. In this particular embodiment each eccentric 6 is staggered some 60° to each adjacent eccentric 6. This leads to a reciprocating action for the blades 3 such that the minimum number of blades 3 are travelling forward with respect to the frame 2 at the same time. This means that a minimum of vibration is transmitted to the frame 2, and the blades 3 move through the soil in a more efficient manner. In more detail, the frame 2 mounts six con rods 8, from a transverse bar 9 running across the top of the frame 2. The con rods 8 are each pivotably mounted at pivot points 10 to allow for reciprocating motion. The SUBSTITUTESHEET con rods 8 are also relatively long so that reciprocating motion about the pivot point 10 results in relatively little vertical motion of the end of the con rod 8 remote from the pivot point 10. The remote end of each con rod 8 is generally of flattened "blade-like" form and extends through a gap between a con rod stabiliser 11 only schematically illustrated in Figure 2 and described in more detail later with reference to Figure 6. The stabilisers 11 act to stabilise the remote end of each con rod 8 so that no lateral motion is allowed outside the plane of the reciprocating motion. A cutting blade 3 is attached to the flat end of each con rod 8 below the guide stabilisers 11. Each cutting blade 3 has a sharp forward edge and can be provided with a bullet 3a at its lower extremity for cutting drainage channels in the soil. A rear transverse beam 20, of the frame 2, which is here shown to be a hollow beam, supports a gear box 23. The gear box 23 has a socket 24 for an input shaft 24a to be provided for a towing vehicle. It also has an output drive shaft 5 running transverse to the gear box and the frame. When the gear box 23 is connected to the drive means of a towing vehicle (not shown) via the input shaft socket 24 power can be transmitted to turn the output drive shaft 5. At the rear end of the frame 2 independently supported by brackets 30 which are pivotably attached to the rear transverse beam 20, are three rollers 31, which are biased downwards, each aligned with a respective cutting blade 3, for smoothing down the turf or soil following agitation by the device. There are only three rollers 31, each roller 31 being of such a dimensional extent to extend across channels cut by two of the preceding cutting blades 3. We have found that this is the best arrangement for ensuring that rollers pivotable about a substantially vertical axis SUBSTITUTE SHPET press down the surface turf surrounded by the cut channels. Prior art devices utilise a single roller for each cutting blade, and are sometimes not effective. The rollers are also mounted so that they support part of the weight of the machine, and therefore need not be as heavy in themselves. This is achieved by a novel bracket 30 arrangement. Referring to Figure 14, the bracket 30 is mounted to the underside of frame 2 by a pivoting mounting 30a. The The mounting 30a is not shown itself, but comprises a horizontal pin passing through holes 30f, 30g in bracket 30 and also passes through a swivel eye bolt 30h connected to the frame 2. The swivel eye bolt allows for movement in three dimensions of the bracket 30 (pivoting on a vertical and horizontal axis). A block 30d is mounted in a housing 30i on bracket 30 and supported by a spring 30j. A roller 30k abuts against the underside of the frame 2, and assists on sideways motion of the bracket 30. the weight of the machine 1 causes the bracket 30c to pivot about mounting 30g until the roller 30k abuts against the frame 2. When the bracket 30 abuts the frame 2, the roller 31 is supporting the weight of the machine. This has the advantage that the rollers need not be as heavy as if they are merely being dragged behind the machine, because, in addition to the roller weight, the weight of the machine is also being utilised to press down on the soil or turf and smooth over the channels cut by the blades 3. The roller 31 may be a hollow steel cylinder. Wheels on the machine (not shown) may in fact be dispensed with totally, and the rollers used to support the machine, along with a tow bar from the towing vehicle. Wheels may, however, be provided at either side of the machine to facilitate motion over, the ground. The frame 2 may also be covered with a cowling (not shown) . SUBSTITUTESHEET The roller 31 is adjustable in height by means of pin 30m passing through bracket 30 and roller supporting bracket 3On through any pair of selected holes 30o, 3Op, 30q. A scraper blade 30r is mounted on roller support bracket 3On in proximity to roller 31. SUBSTITUTESHEET The rollers 31 may be adjustable in height in order to adjust the height of the machine from the ground. In operation, the device 1 will be towed by a tractor or other towing vehicle (not shown), with a drive connected from the towing vehicle to the device gear box. Note that, for the cutting blades 3, blades in accordance with our co-pending International patent application No PCT/AU91/00344 could be employed. An embodiment of the drive linkage of the present invention will now be explained in detail with reference to Figures 5 and 7. The mechanism comprises an eccentric 6 mounted for rotation on a shaft 5. The shaft 5 is connected to a gear box 23 which takes power from a drive shaft 24 as discussed above. Figure 5 is an exploded and detailed view of the drive mechanism used in the agitating device of Figures 1 through 4. The eccentric 6 in each case is connected to a further linkage point 50 midway along a supporting member 51 to drive a first linkage 55, by a drive member 52. The supporting member 51 is shown cut away with the top half thereof having been removed. It will be appreciated that in the operating mechanism the supporting member 51 will be complete. In the mechanism illustrated in Figures 1 to 4 the supporting member 51 is shown connected directly to the fist linkage 55, with no further linkage point 50. However, the connection arrangement of Figure 5 is preferred, as it allows for increased "throw" of the reciprocating path of the first linkage 55 with a minimum size of eccentric 6. On rotation of the eccentric 6 the first linkage 55 is caused to move along a predetermined first path. A supporting linkage 58 is connected to the first linkage 55 SUBSTITUTESHEET by a connecting rod 51. The connecting rod 51 is mounted at the linkage 58 to the frame 2 of the soil agitation device such that it is pivoted to the frame. Rotation of the eccentric 6 causes movement of the linkage 55 in a substantially vertical but arcuate path. The radius of the arc is the length of the member 57 with centre of radius at linkage 58. A second linkage 59 is connected to the pivoted con rod 8 which mounts the blade 3. The linkage 59 is also connected to the linkage 55 by rigid member 59a, 59b so that when the linkage 55 moves along the first path the linkage 59 moves along a second path. This causes motion of the blade in a reciprocating fashion, as the con rod 8 is pivoted to the frame of the agitating device at 10. It will be noted that a rigid member 59a, 59b, comprises two connecting rods. This is the preferred arrangement, although a single connecting rod may suffice in some cases. Figure 7 is a schematic diagram of the mechanical linkage of the invention which we will use to explain the operation thereof. Circle 65 and member 66 are a "mechanical equivalent" to eccentric 6 and connecting rod 52 of Figure 5. Circle 65 is arranged to rotate around point 0 therefore causing rotation of the point 67 on member 66 to traverse a substantially orbital path, generally coincident with the circumference of circle 65. Note that the orbital motion need not necessarily be circular, but could be any other type of orbital motion required. As circle 65 rotates, linkage 68, equivalent to linkage 55 of Figure.5, describes the path.illustrated by broken line 69. The path is substantially vertical but somewhat arcuate. Linkage 68 is constrained for movement in this first path by linkage 71, connecting rigid member 70 to a frame. Linkage 71 is equivalent to linkage 58 of Figure 5. It should be noted that linkage 71 and member 70 is a preferred feature of the invention only. There SUBSTITUTESHEET are other ways in which it would be possible to constrain the motion of linkage 68. For example, a slide type guide and follower arrangement could be used. The follower being mounted on linkage 68 to fit into the guide which would be mounted to the frame. Other means could also be used. As linkage 68 moves along path 69, the second linkage 72 is caused to move along path 73. Linkage 72 is connected to linkage 68 by a connecting rod 74. Con rod 75 which mounts the blade 76 follows the motion of the second linkage 72. Linkage 72, connecting rod 74, con rod 75 and blade 76 are equivalent to linkage 59, member 59a, 59b, connecting rod 8 and blade 3, respectively, in Figures 1 and 5 In operation, as circle 65 is at three o'clock linkage 68 is passing along path 69 through point M, and at this point it has its maximum velocity of motion. When point 67 reaches six o'clock on the circle, linkage 68 is at the lower extreme of its path of motion and its speed is at a minimum, by virtue of the geometry of the connection when point 67 is about the 3 o'clock point, most of the angular motion of circle 65 is being converted to vertical motion of 68 by rod 66; when point 67 is about 6 o'clock, there is only a little vertical motion for an equivalent angular traverse. Further, when the point 67 is at nine o'clock in the circle linkage 68 is again passing through the mid path point and at maximum velocity, and when point 67 is at twelve o'clock on the circle linkage 68 is at its upper extreme of motion and to and its velocity is again at a minimum. What this means for the second linkage 72, is that for each rotation of the circle 65 the linkage 72 will traverse its path of motion twice, and will be at its maximum velocity about point M on line 73. This "double action" of the con rod 75 in response to the single traverse of the path 69 by centre linkage 68 results in an increased efficiency of the device. Further, because of the geometry of the motion of the centre linkage 68, the velocity of the blade 76 is at a maximum as it cuts into the grass or soil, i.e. about the point where the blade is at its furthest extent (point M on the upper motion 73). This means that the grass or turf is cut as opposed to torn, by a chopping action. The geometry of the arrangement may be changed to give variation in stroke and where the maximum velocity occurs on the stroke. For example, the linkage could be arranged such that one stroke of the reciprocating member is shorter than the other. Further, because the linkage is connected at all times to the rod 75, the blade is always being power driven. Noise is much reduced and efficiency is increased. The eccentric 56 works in the same way as circle 65 and rod 66. The position of the centre linkage may be altered to vary the "double action" stroke. For example, one stroke may be arranged to be longer than the other stroke, ie, to give a short "chopping" action interspersed with a long stroke. The linkage may be arranged to give a positive rise to the stroke, by varying the geometry thereof. As can be seen from the detailed drawing of figure 5, the blade 3 is mounted on the con rod by means of nuts and bolts, A, B, and mounting plate C. In fact, a number of nuts and bolts, A, B, are utilised to mount the linkage. The linkages themselves are formed in a hinge like manner by hollow pins D rotatable within holes E through the linkages, and fastened by nuts and bolts A, B. The eccentric 6 is in the form of an enclosed bearing received within one end of the drive member 52. Suitable bearings are Nachi 6015/2NCL bearings. The conrods 8 are SUBSTITUTESHEET preferably of aluminium. A stabiliser arrangement for each turf cutting arm will now be described in detail with reference to Figure 6. The arrangement is generally designated by reference numeral 11, and is only schematically illustrated in Figure 2. The arrangement comprises four roller bearings 600, 601, 602, 603 mounted at either side of each con rod 8 on mountings 604, 605. The mountings may be made of metal. Pins 606, 607, 608, 609 pass through the mountings (which in cross section are an open "D" shape) and bearings 600, 601, 602, 603, and the bearings roll about the pins during reciprocating motion of the con rod 8. The bearings thus maintain the con rod in its reciprocating path, minimising any undesirable lateral motion. Screws 610, 611, 612, 613 are mounted in nuts 614, 615, 616, 617 in plates 618, 619 which are mounted to the frame 2 by brackets (not shown) . Adjustment of the screws within the nuts allows for adjustment of the rollers position against the con rod 8. Figure 8 is a schematic view of a mechanical linkage in accordance with the present invention which incorporates four linkages 300, 301, 302, 303. The first linkage 300 is connected to a driving eccentric 304 by a connecting rod 305. The linkages 300, 301, 302, 303 are connected to each other by respective connecting rods 306, 307, 308. The linkages 300, 301, 302 are also connected to supporting linkages 309, 310, 311, respectively, mounted on a stable frame (not shown, but may be the frame of an agricultural device, for example). The supporting linkages are connected to the linkages by supporting rods 312, 313, 314. The supporting linkages and rods constrain the linkages 300, 301, 302 within predetermined paths of reciprocation when the drive eccentric 304 is rotated. Final linkage 303, would, in operation, be attached to a reciprocable implement (not shown) . The arrangement SUBSTITUTESHEET is such that for each reciprocation of the first linkage, the final linkage 303 will traverse 2^ n ~ - 1 reciprocations, where n = number of linkages in the sequence. In other words, the final linkage 303 will traverse 8 reciprocations for every one reciprocation of the first linkage 300. The arrangement can be configured to make sure that maximum velocity magnitude occurs about the outer extreme of reciprocation of the linkage 303, by determining when the maximum magnitude of velocity of linkage 300 occurs and configuring the system, by positioning of linkages, such that this coincides with the final linkage 303 reaching its outer extreme of reciprocation. The turf aerator of our Australian patent No. 572915 may also utilize a mechanical linkage in accordance with the present invention. Referring to Figures 9 through 11, an aerator 110 of the invention has a frame 111. To frame 111 are mounted at least two ground engaging wheels 112. These wheels are mounted for rotation about an axle 113 extending transversely of the aerator. The wheels may function as depth wheels to provide for adjustability of the height at which the aerator travels over the ground. In one form the axle 113 may have a cranked portion and the position of this portion relative to the frame may be adjusted to provide for this height adjustment. This adjustment not only enables the height of the aerator to be varied between a transport position and an operating position but also enables adjustability of the aerator to achieve varying heights of the operating position. In the transport position the aerator may be freely towed by a vehicle to selected areas of turf to be aerated. The aerator 110 has a crankshaft 1-14 extending transversely of the frame 111. The crankshaft is supported by main bearings 115, 116 and 117 and carried by SUBSTITUTESHEET support members 118 integral with the frame 111. Whilst only one crankshaft 114 is illustrated where a wider aerator is required two crankshafts 114 may be coupled end to end. The aerator includes drive means for rotating the crankshaft. The drive means illustrated comprises a gearbox 120 having an input shaft 121 and an output shaft 112. The input shaft 121 may be coupled to a power take off of the towing vehicle. The gearbox is fixed relative to mount 123 secured to a member of the frame 111. The crankshaft 114 may be suitably driven from the gearbox via a drive chain 124 extending over drive sprockets 125, 126. Where there are two crankshafts they may be driven by respective drive chains from the output shaft of the gearbox or alternatively by a duplex chain meshing with respective single sprockets on adjacent ends of the crankshafts. This provides a simple, flexible coupling between separate crankshafts. Alternatively the shafts may be driven from their remote ends via suitable drives from spaced take off means on a common shaft or from the opposite ends of a conventional vehicle rigid rear driving axle assembly. A chain connection is convenient since it permits the respective crankshafts 114 to be timed with respect to one another to place the throws of one shaft out of phase with the throws of the adjacent shaft. This has the advantage of staggering tyne arms 130 and hence tynes 131 engage the ground in a staggered fashion resulting in smoother operation of the aerator. Tyne arms 130 are mounted relative to the crankshaft. A bearing 132 is located between the upper end of each arm 130 and the crankshaft. The frame has a transverse frame member 133 formed with a plurality of slots 134. It is within these slots that the arms 130 are located and travel. The arms are biased towards the rear of the slots by respective springs 135. These slots act SUBSTITUTESHEET as guides for the movement of the arms. Mounted at the lower end of each arm 130 is a tyne foot 136 which carries at least one tyne. Preferably two or more tynes are carried by the foot. The foot may be formed integral with the arm 130. It is preferred that it be detachable. Mounted at spaced intervals transversely across the aerator are a series of buffers 150. The number of buffers corresponds to the number of tyne arms 130. The buffers are mounted on a transverse frame member 151 and each comprise a roller 152 rotatably mounted on support 153 by axle 154. As the arms 130 are brought back into the slots 135 by springs 135 the buffers ensure that there is no jarring metal to metal contact during motion. If desired the rear of the slot may be cushioned in some suitable fashion. It will be seen that each time the arm 130 strikes the buffer 150 the roller 152 presents a different part of its periphery for the next buffering action. To ensure that turf is not lifted from the ground when the tynes are withdrawn the aerator is provided with a guard 160. The guard 160 is secured to a member of the frame and extends from this member past the area over which the tynes operate. The guard, during use, is in contact with the ground and may be biased against it. The guard has a forward inclined portion 161 attached to the frame and a rear ground engaging portion 162. The free end of the rear portion 152 has a turned up end 163. End 163 enables the aerator to be reversed without the guard prohibiting such movement. The rear portion is formed with a series of arms which when viewed in plan appear as a comb. A respective arm of this portion extends between adjacent tynes of the foot to ensure that withdrawal of the tynes does not result in lifting the turf. If desired the arms of the rear portion 162 may be SUBSTITUTESHEET provided with a raised portion 164. Raised portion 164 is positioned such that each foot moves over a respective raised portion during its aerating operation. In this way any material such as soil or turf lodged between the transversely spaced tynes may be dislodged from the foot. To assist in this action the forward and trailing bottom edges of the tyne feet may be bevelled. The operation of the aerator is as follows. The crankshaft is caused to rotate in the direction of arrow A, each bearing mount for the tyne arms will move towards bottom dead centre to engage the tynes in the ground. As the aerator advances the bearing mount for the tyne arms move rearwardly due to part rotation of the crankshaft and the tyne arm moves along the slots 134 against the action of springs 135. This action results in the tyne arms being maintained substantially vertical whilst the tynes are engaged in the ground. When each tyne is retracted from the ground by continued rotation of the crankshaft the springs 135 move the tyne arms in the slots 134 ready for the next downward thrust. The frame 111 may be adapted to be supported by a three point linkage and the crankshaft connected to a power take off of a towing vehicle. The drive for the crankshaft could be mechanical as illustrated or could be any other suitable drive such as hydraulic. Soil deflectors 164 may be provided for use with hollow tynes to deflect soil rearwardly as it is pushed up through the tynes. As an alternative to the crankshaft drive illustrated in Figures 7 through 9, a mechanical linkage in accordance with the present invention could be utilised to drive each tyne arm. Drive unit 120 and shaft 122 could be used to power a series of eccentrics mechanically linked to the tyne arms, causing powered reciprocation of the tyne arms. SUBSTITUTESHEET A further embodiment of the present invention as applied in a turf cutting device will now be described with reference to Figures 12 and 13. Both Figures 12 and 13 are schematic diagrams only of a turf cutter, showing the main features only. However a persons skilled in the art will be aware of construction and technicalities of such a device. The only difference between the turf cutter and a standard turf cutter is in the transmission of the drive to the turf cutting blade, which utilises a mechanical linkage in accordance with the present invention. The turf cutter comprises a frame 500 arranged to be pushed along by handle 501. A driving motor 502 may transmit drive to wheels 503 to assist motion of the turf cutter, in a known fashion. The frame 500 also mounts two pivoting supporting arms 504, 505 pivoted to the frame at pivot points 506, 507, respectively. The arms 504, 505 mount, at their ends opposite the pivot points 506, 507 a turf cutting blade 508 which extends substantially horizontally between the remote ends of arms 504, 505. In operation, as the turf cutter travels forwards, the arms 504, 505 are reciprocated backwards and forwards on the pivot points 506, 507, to cause the blade 508 to "chop" into the turf to cut it and therefore allow the turf to be taken up. In this embodiment, the drive means utilised is the mechanical linkage arrangement of the present invention. A wheel and chain arrangement 509, 510, transmits drive from the driving motor 502 to a wheel 511 supported on a drive shaft 512. The drive shaft 512 is mounted for rotation in known manner to the frame 500 of the turf cutter. Mounted on the driveshaft are eccentrics 513, 514, respectively, which transmit motion to driving rods 515, SUBSTITUTESHEET 516 mounted on the eccentrics by sealed bearings 517, 518. Driving rods 515, 516 connected to a first linkage 517, 518 respectively. A second linkage 519, 520 is connected to supporting arms 504, 505, respectively, and a supporting linkage 521, 522 is mounted to the frame 500 and connected to the first linkage 517, 518 in each case, by a supporting rod 523, 524. The mechanical linkage of the turf cutter is basically the same as that described in detail in relation to the soil agitation device embodiment of the present invention described above. In operation, rotation of the eccentric 513, 514 causes reciprocation of the first linkage 517, 518 along a reciprocating path. Each linkage 517, 518 is constrained for movement within its reciprocating path by supporting rods 523, 524 and supporting linkages 521, 522, respectively. Reciprocation of the respective first linkages 517, 518, causes reciprocation of the second linkages 519, 520, in a reciprocating path which is substantially perpendicular to the reciprocating path of the first linkage. In turn this causes reciprocation of the supporting arms 504, 505, and the desired motion of the turf cutting blade 508. The eccentrics 5 * 13, 514 are synchronised to ensure that both arms 504, 505 are reciprocated at the same time. The motion imported by the linkage arrangement is such that for every single turn of the eccentric the blade 508 travels through two reciprocations. Preferably, the linkage is also arranged such that maximum velocity magnitude of the blade occurs about the extreme of reciprocation furthest forward into the turf to give the advantages of "fast attack", "fast drop off" and "fast turnaround" discussed above. Elements 514, 516, 518, 520, 522, 524 are not shown SUBSTITUTESHEET in the drawing. It will be appreciated that they are the same as elements 513, 515, 517, 519, 521, 523. It will be appreciated by persons skilled in the art SUBSTITUTESHEET that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. SUBSTITUTESHEET

Claims: CLAIMS : - 1. A mechanical linkage arrangement, for connecting a reciprocable member to a drive means and for driving the reciprocable member in a reciprocating fashion in response to actuation of the drive means, the mechanical linkage arrangement being arranged to impart motion to the reciprocable member such that if the drive means is travelling at a substantially constant velocity magnitude the magnitude of the velocity of the reciprocable member varies along its path of reciprocation and is a maximum about one extreme of the reciprocation. 2. A mechanical linkage arrangement in accordance with claim 1, comprising first and second linkages, the first linkage being arranged to describe a reciprocating path in response to the drive means and the second linkage describing a reciprocating path in response to the motion of the first linkage. 3. A mechanical linkage arrangement in accordance with claim 2, arranged such that for a single reciprocation of the first linkage the second linkage is driven through a plurality of reciprocations. 4. A mechanical linkage arrangement in accordance with claims 2 or 3, wherein the second linkage is connected directly to the reciprocable member. 5. A mechanical linkage arrangement in accordance with any of claims 2 to 4, the first linkage being connected to a supporting linkage by a substantially rigid supporting member, the supporting linkage being mounted on a frame, whereby to constrain the motion of the first linkage in its reciprocating path. 6. A mechanical linkage arrangement in accordance with claim 5, wherein the first linkage is connected to the drive means via a substantially rigid connecting member. 7. A mechanical linkage arrangement in accordance with claims 5 or 6, wherein the connecting member is connected SUBSTITUTE SHEET to the supporting member by a further linkage which is approximately midway between the first linkage and the supporting linkage. 8. A mechanical linkage arrangement in accordance with any of claims 5 to 7, wherein the first linkage is connected to th second linkage by a first substantially rigid member. 9. A mechanical linkage arrangement in accordance with any one of claims 2 to 8, wherein the reciprocating paths of the fist and second linkages are substantially perpendicular to each other. 10. A mechanical linkage arrangement in accordance with any one of the preceding claims the drive means comprising a drive member arranged to describe an orbital path in response to drive and the mechanical linkage arrangement being arranged to convert the angular motion of the member to linear reciprocating motion of the reciprocable member. 11. A mechanical linkage arrangement in accordance with claim 10, the drive member being a rotating eccentric mounted on a drive shaft. 12. A mechanical linkage arrangement in accordance with claims 10 or 11, arranged such that at about one point on the orbital path the angular motion is converted onto maximum traverse of linear motion, being about one extreme of reciprocation of the reciprocating member. 13. A mechanical linkage arrangement in accordance with any of claims 2 to 12 wherein the linkage is arranged such that the first linkage velocity magnitude is at a maximum at the centre of its reciprocating path and the second linkage is at one extreme of its motion at that time. 14. A mechanical linkage arrangement in accordance with claim 1, comprising a plurality of sequentially connected linkages, being at least three linkages, a first linkage being arranged to describe a reciprocating path in response to the drive means, a second linkage connected to SUBSTITUTESHEET said first linkage and being arranged to describe a reciprocating path in response to the motion of the first linkage, a third linkage being connected to said second linkage and being arranged to describe a reciprocating path in response to motion of said second linkage, etc for any other sequentially connected linkages. 15. A mechanical linkage arrangement in accordance with claim 14, arranged such that, in an arrangement having n linkages, for a single reciprocation of the first linkage the nth linkage is driven through 2' n ~ ' reciprocation. 16. A mechanical linkage arrangement in accordance with claims 14 or 15, wherein each of the sequentially connected linkages, apart from the final linkage, which is connected to the reciprocable member, are connected to respective supporting linkages by respective substantially rigid supporting members, the respective supporting linkage being mounted on a frame, whereby to constrain the motions of the respective sequentially connected linkages within their respective reciprocating paths. 17. A mechanical linkage arrangement in accordance with claim 17, wherein the first linkage in the sequence is connected to th drive means via a substantially rigid connecting member. 18. A mechanical linkage arrangement in accordance with claims 16 or 17, wherein each linkage is connected to the subsequent linkage in the sequence by a substantially rigid member. 19. A mechanical linkage arrangement in accordance with claims 14 to 15, the drive means comprising a drive member arranged to describe an orbital path in response to drive and the mechanical linkage arrangement being arranged to convert the angular motion of the member to linear reciprocating motion of the reciprocable member. 20. A mechanical linkage arrangement in accordance with claim 19, the drive member being a rotating eccentric SUBSTITUTE SHEET mounted on a drive shaft. 21. A mechanical linkage arrangement in accordance with claims 19 or 20 arranged such that at about the angular motion is converted onto maximum traverse of linear motion, being about one extreme of reciprocation of the reciprocating member. 22. A mechanical linkage arrangement, for connecting a reciprocable member to a drive means and for driving the reciprocable member in a reciprocating fashion in response to actuation of the drive means, the mechanical linkage arrangement comprising a plurality of sequentially connected linkages, including at least a first linkage connected to the drive means and at least a final linkage connected to the reciprocable member, each subsequent linkage in the sequence being arranged to describe a reciprocating path in response to reciprocating motion of the preceding linkage and wherein, in an arrangement having n linkages, for a single reciprocation of the first linkage the final linkage is driven through 2^ n ~ ' reciprocations. 23. A mechanical linkage arrangement in accordance with claim 22, wherein each of the sequentially connected linkages, apart from the final linkage, which is connected to the reciprocable member, are connected to respective supporting linkages by respective substantially rigid supporting members, the respective supporting linkage being mounted on a frame, whereby to constrain the motions of th respective sequentially connected linkages within their respective reciprocating paths. 24. A mechanical linkage arrangement in accordance with claim 23, wherein the fist linkage in the sequence is connected to the rive means via a substantially rigid connecting member. 25. A mechanical linkage arrangement in accordance with claims 23 or 24, wherein each linkage is connected to the SUBSTITUTESHEET subsequent linkage in the sequence by a substantially rigid member. 25. A mechanical linkage arrangement in accordance with any one of claims 23 to 25, the drive mean comprising a drive member arranged to describe an orbital path in response to drive and the mechanical linkage arrangement being arranged to convert the angular motion of the member to linear reciprocating motion of the reciprocable member. 26. A mechanical linkage arrangement in accordance with claim 25, the drive member being a rotating eccentric mounted on a drive shaft. 27. A mechanical linkage arrangement in accordance with claims 25 or 26 arranged such that at about the angular motion is converted on to maximum traverse of linear motion, being about one extreme of reciprocation of the reciprocating member. 28. A mechanical linkage arrangement in accordance with any of claims 24 to 27, wherein there are only two sequentially connected linkages, being the first linkage and the final linkage. 29. A mechanical linkage arrangement in accordance with claim 28, wherein the connecting member is connected to the supporting member by a further linkage which is approximately midway between the first linkage and the supporting linkage. 30. A mechanical linkage arrangement in accordance with claims 28 or 29, wherein the reciprocating paths of the fist and second linkages are substantially perpendicular to each other. 31. A mechanical linkage arrangement, comprising a drive means for driving a reciprocable member in a reciprocating fashion and a linkage arrangement connecting the drive means to the reciprocable member, the drive means comprising a rotatable eccentric mounted on a drive shaft, and the linkage arrangement comprising a plurality SUBSTITUTESHEET sequentially connected linkages, being connected by connecting rods, and being at least a first linkage connected to the eccentric by a connecting rod and at least a final linkage connected to the reciprocable member, each subsequent linkage in the sequence being arranged to describe a reciprocating path in response to reciprocating motion of the preceding linkage, each linkage in the sequence, apart from the final linkage, being connected to respective supporting linkages by connecting rods, the respective supporting linkages being mounted on a frame, whereby to constrain the motions of the respective sequentially connected linkages within their respective reciprocating paths. 32. A mechanical linkage arrangement in accordance with claim 31, wherein there are only two sequentially connected linkages, being the first linkage and the final linkage. 33. A mechanical linkage arrangement in accordance with claim 32, wherein the connecting rod connecting the first linkage to the eccentric is connected to a further linkage on the connecting rod connecting the firs member to its respective supporting linkage. 34. A mechanical linkage arrangement in accordance with claims 32 or 33, wherein the reciprocating paths of the first and second linkages are substantially perpendicular to each other. 35. A mechanical linkage arrangement in accordance with any preceding claim wherein the linkages comprise huge links between connecting rods. 36. A device for agitating soil, comprising a frame arranged to be towed or pushed or self propelled and mounting at least one cutting blade arranged to penetrate the soil and cut a channel therein as the frame moves along, the blade being mounted for reciprocating motion along a line coincident with the direction of cutting, SUBSTITUTESHEET drive means for providing drive for causing reciprocating motion of the cutting blade, and a mechanical linkage arrangement connected to the drive means for causing reciprocating motion of the cutting blade, the mechanical linkage arrangement being the arrangement of any one of claims 1 to 21. 37. A device for agitating soil, comprising a frame arranged to be towed or pushed or self propelled and mounting at least one cutting blade arranged to penetrate the soil and cut a channel therein as the frame moves along, the blade being mounted for reciprocating motion along a line coincident with the direction of cutting, drive means for providing drive for causing reciprocating motion of the cutting blade, and a mechanical linkage arrangement connected to the drive means for causing reciprocating motion of the cutting blade, the mechanical linkage arrangement being the arrangement of any one of claims 22 to 35. 38. A device for agitating soil in accordance with claims 36 or 37, the cutting blade being supported by a pivotable arm to which the mechanical linkage is connected, the pivotable arm being stabilised between lateral stabilising members, comprising two paris of position adjustable rollers abutting the pivotable arm. 39. A device for agitating soil in accordance with claims 36, 37 or 38, wherein there are a plurality of cutting blades, and a plurality of rollers are mounted to the frame behind the cutting blades, each roller extending across the width of just over two blades. 40. A device in accordance with claim 39, wherein the weight of the rear of the device is supported by the roller. 41. A device in accordance with claims.39 or 40, wherein the rollers are adjustable in height position. 42. A turf cutting device, frame arranged to be towed or SUBSTITUTESHEET pushed or propelled and comprising a turf cutting blade arranged to penetrate the turf and extending substantially horizontally between a pair of supporting arms mounted to the frame for reciprocation, drive means for providing drive for causing reciprocating motion of the arms, and a mechanical linkage arrangement connecting the drive means to each arm, the mechanical linkage arrangements being in accordance with any one of claims 1 to 35. 43. An aerating machine for turf, comprising a frame arranged to be towed, pushed or self-propelled, said aerating machine comprising an aerator frame mounting a plurality of rigid tyne arms arranged for reciprocation such that a tyne at the end of each tyne arm is arranged to pierce the turf as the machine moves along, a drive means for providing drive for causing reciprocating motion of the tyne arms, and a mechanical linkage arrangement connecting the drive means to each tyne arm, the mechanical linkage arrangements being in accordance with any one of claims 1 to 35. 44. A roller support arrangement for a soil agitating device, comprising a bracket arranged to be pivotally mounted to a frame of the soil agitating device, being arranged to abut the frame whereby the roller takes the weight of the machine.

Inventors: LIVINGSTONE DAVID JOHN, LIVINGSTONE, DAVID, JOHN
Applicants: GREENCARE PTY LTD, GREENCARE PTY. LTD.
Application year: 1991
Main classification: A01B45
IPC codes: A01B33, A01B45, F16H21