AU2013201331B2 - Tillage apparatus - Google Patents

Abstract

An improved zero-till tillage apparatus is described. Embodiments include a double disk opener that is robust and can perform well in many different soil types and conditions, although the apparatus is versatile and can be used with plain or scalloped coulter disks or tyne openers. The apparatus includes a depth control assembly which provides an easy, reliable and uniform method for controlling the depth. In one embodiment this includes a spring pin arrangement with fixed increments which allows for quick, easy and uniform adjustment of multiple individual tillage units. The coulter disk arm is angled forward to provide a compact and unique design, as this keeps the press wheel much closer to coulter disk and the sowing boot. This allows tighter turning with less stress on the tillage apparatus and less soil drag. The apparatus is a true parallelogram unit so as to allow the opener to follow ground contours providing for more uniform seed placement. Additionally a slot arrangement is used to facilitate mounting of the parallelogram assembly. Height control is achieved using either a spring or hydraulic arrangement. '24 15 't21a 12 414 851b 26 51a 70 7 88,6 75 80 84c 7 84b Figure 1

Description

1 TILLAGE APPARATUS TECHNICAL FIELD [0001] The present invention relates to agricultural tillage apparatus. In a particular form the invention relates to a zero-till double disk opener apparatus. PRIORITY DOCUMENTS [0002] The present application claims priority from Australian Provisional Patent Application No. 2012900871 titled "Tillage Apparatus" and filed on 6 March 2012, the content of which is hereby incorporated by reference in its entirety. BACKGROUND [0003] Agricultural tillage apparatus are used to mechanically manipulate soil conditions for the enhancement of crop production. Various types of tillage exist such as no-till or zero-till, direct drill seeding and minimum tillage. No-till or zero-till apparatus refers to tillage apparatus which only disturbs the soil a necessary amount so as to place the seed and thus typically only the portion of the soil in the seed row is disturbed. [0004] Individual tillage apparatus typically comprise a frame, a mounting assembly, and a ground or soil engaging component. The ground engaging component is typically attached to a vertical shank which is attached to the frame. A contour or ground following member, typically a press wheel, is attached either to the shank or frame to follow the ground contour and to maintain the ground engagement component in a fixed relative geometry to the ground follower. Hence when the ground follower rises or falls the ground engaging component rises and falls in concert with the ground follower to ensure seeds are always placed at the desired depth. [0005] The mounting assembly allows mounting to the towing implement or frame which is towed by a vehicle such as tractor. The towing implement will typically have between about 10 and 30 individual tillage assemblies attached to one or more beams. The mounting assembly also includes a parallelogram (or other) arrangement to control the amount of down force onto the ground engaging apparatus so as to maintain the required soil depth penetration and hence the depth of seed placement. In a parallelogram arrangement a bias force is supplied between selected arms of the parallelogram to provide a downward force and to guide the ground engaging component and the follower.

2 [0006] Typical ground engaging components include an opener, which "opens" a continuous cleft, furrow or undercut in the soil to allow for subsurface seed and/or fertilizer deposition in a row. These opener components are also referred to as seed boots, seed shoes, seed openers, furrow openers, or seed furrow openers, disc openers, tynes, shares or tillage points. Soil opening for seed placement may or may not be preceded by soil and residue cutting components and/or row preparation components, depending on the type of opener used, the soil surface condition, and the required seeding practice for the type of crop and/or soil condition. The performance of an opener component will depend upon factors such as its travel velocity, the type and condition of soil, the level of residue, and the required seeding depth which is typically 30-50 mm for wheat, 5-10 mm for pasture and various other depths to suit the seed type being planted. [0007] Some zero-till apparatus use double disc openers as the ground engaging component in which two slightly off-centre disks are used to engage and open the ground to a desired depth to allow placement of a seed and (optionally) fertilizer. Double disk openers provide benefits such as more uniform seeding depth, reduction in draft forces, improved trash handling ability, reduced soil disturbance and faster sowing speeds. In some cases disc openers are more suitable than tynes when sowing into rocky conditions. Further sowing with a double disc opener leaves a smoother soil profile and will assist in reducing water run-off. However whilst double disk openers can provide zero-till benefits, they are often quite long, which leads to high stress on the components during tight turning operations, as well as having a tendency to drag the soil and thus excessively disturb the soil. [0008] Tillage apparatus typically include some form of depth control mechanism to control and maintain the depth of seed placement. However many of these are complicated, which adds further cost, and/or difficult and time consuming to adjust . Further in many cases there are many (eg 10-30) individual tillage units attached to a towing implement, and it is often difficult to uniformly adjust each unit. [0009] There is thus a need to provide an improved tillage apparatus, or at least provide users with a useful alternative. SUMMARY [0010] According to a first aspect, there is provided a tillage apparatus including: a support frame, a mounting assembly including a mounting portion for mounting to a towing implement; a parallelogram assembly for linking the mounting assembly to the support frame and adapted to allow height adjustment of the support frame relative to the towing implement, and including an adjustable down force controller apparatus to control the down force on the support frame; and 3 a ground engaging assembly attached to the support frame via a forward arm; a ground following assembly including a ground following member attached to the support frame via a rear arm; and a depth control assembly for controlling the depth of the ground engaging assembly relative to the ground following member and a depth selector which allows selection of one of a set of predefined depths of the ground engaging assembly relative to the ground following member within a depth range, wherein the rear arm is mounted on a shaft passing through the support frame and the depth control assembly includes a pin and a plurality of apertures to lock the angle of the rear arm with respect to the support frame. [0011] In a further aspect, the depth control assembly controls the angle of the forward arm with respect to the rear arm. The forward arm may be angled forward of the vertical so as to locate the ground engaging component under the mounting assembly, wherein the angle is selected to be as large as possible whilst providing clearance between the ground engaging component and mounting assembly. The angle may be in the range of 25' to 35'. The ground engaging component may be a double disk opener. The ground following member may be a press wheel. [0012] In a further aspect, the parallelogram assembly includes an upper rectangular frame and a lower rectangular frame which are mounted so that a plane containing the upper frame is kept parallel to a plane containing the lower rectangular frame, the upper rectangular frame including a first upper arm, a second upper arm, a first upper shaft and a first lower shaft, the first upper shaft located near one end of the first and second upper arm and connecting the first and second upper arms, and the first lower shaft located near the other end of the first and second upper arms and connecting the first and second upper arms to define the upper rectangular frame. The lower rectangular frame including a first lower arm, a second lower arm, a second upper shaft and a second lower shaft, the second upper shaft located near one end of the first and second lower arm and connecting the first and second lower arms, and the second lower shaft located near the other end of the first and second lower arms and connecting the first and second lower arms to define the lower rectangular frame. The mounting assembly includes a first plate and a horizontally spaced second plate for supporting a mount for receiving a towing implement beam (or arm). Further each of the first and second plates including a vertical slot with a centrally located rearward aperture to allow insertion of the first upper shaft and the first lower shaft and a cover plate receiving aperture. The mounting assembly also includes two cover plates (one for the first plate and one of the second plate), each with upper and lower apertures for receiving the first upper shaft and the first lower shaft, and a projection which is located in the cover plate receiving aperture to lock the cover plate in place. The support frame portion includes a first support plate and a horizontally spaced second support plate (via members, rods etc), and each of the first and second support plates including a vertical slot with a centrally located forward aperture to allow insertion of the second upper shaft and the second lower 4 shaft and a cover plate receiving aperture. Further (when assembled) the support frame includes two cover plates (one for each side of the support frame), each with upper and lower apertures for receiving the second upper shaft and the second lower shaft, and a projection which is located in the cover plate receiving aperture to lock the cover plate in place. [0013] In a further aspect, the adjustable down force controller apparatus may include an upper mount and a lower mount, the upper mount including a shaft which passes through an aperture in the first upper arm and the second upper arm of the parallelogram assembly, and the lower mount including a shaft which passes through an aperture in the first lower arm and the second lower arm of the parallelogram assembly. [0014] In a further aspect, the adjustable down force controller apparatus is a spring based down force controller including a centrally threaded rod with a bolt head mounted between the upper spring mount and lower spring mount with a bolt head, and an adjustment nut fastened to a lock plate, and a spring mounted coaxially with the threaded rod between the lock plate and the lower spring mount, wherein rotation of the bolt head adjusts the location of the lock plate along the threaded rod to control compression of the spring and down force transferred to the support frame. [0015] In a further aspect, the adjustable down force controller apparatus is a hydraulic apparatus to control the distance between the upper and lower mount so as to control the down force transferred to the support frame, and may further include a pressure gauge and a control line to allow an operator to remotely monitor and control the down force. A spring may be located between the upper and lower mount so as to provide a spring return mechanism to allow raising of the apparatus off the ground. [0016] In a further aspect, the support frame includes a first body plate that includes a first set of apertures and the rear arm includes a second set of apertures. The rear arm may further include a pin plate mounted on the rear arm, and the second set of apertures may be located in the pin plate. The pin may be mounted in a spring arm which is pivotally mounted to the support frame, wherein the spring arm provides a biasing force to force the pin in an aperture, and the spring arm may include a tab on the end opposite the pivot so as to allow removal of the pin from an aperture. The depth selector may be hydraulically controlled. BRIEF DESCRIPTION OF DRAWINGS [0017] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein: [0018] Figure 1 is an isometric view of tillage apparatus according to an embodiment; 5 [0019] Figures 2A and 2B are a side views of hydraulic tillage apparatus at a minimum and maximum height according to an embodiment; [0020] Figures 2C and 2D are a side views of spring tillage apparatus at a minimum and maximum height according to an embodiment; [0021] Figure 2E is a close up view of a slot arrangement according to an embodiment; [0022] Figure 2F is a close up view of a depth control assembly according to an embodiment; [0023] Figures 3A and 3B are side and rear views of a support frame, a forward arm, and a ground following rear arm according to an embodiment; [0024] Figure 3C and 3D are side and rear views of a first body plate according to an embodiment; [0025] Figure 3E is a side view of spring pin according to an embodiment; [0026] Figures 3F and 3G are side and rear views of pin plate according to an embodiment; [0027] Figure 4 is an isometric view of depth control assembly according to an embodiment; [0028] Figure 5 is an isometric view of parallelogram assembly according to an embodiment; [0029] Figure 6 is a top view of hydraulic down force controller according to an embodiment; and [0030] Figure 7 is an isometric view of multiple tillage apparatus mounted to a towing implement according to an embodiment. [0031] In the following description, like reference characters designate like or corresponding parts throughout the figures. DESCRIPTION OF EMBODIMENTS [0032] Referring now to Figure 1, there is shown an isometric view of a tillage apparatus (or tillage unit) 100 according to an embodiment. Figure 7 is an isometric view of 24 tillage units mounted to a three beams or arms of a towing implement (or towing frame) 1 2 3. Each tillage apparatus (or tillage unit) 100 includes a support frame 50, a mounting assembly 10, a parallelogram assembly 20 for linking the mounting assembly 10 to the support frame 50, a ground engaging assembly 60, a ground following assembly 70, and a depth control assembly 80. As will be discussed the parallelogram assembly is 6 adapted to allow height adjustment of the support frame relative to the towing frame and includes an adjustable down force controller apparatus to control the down force on the support frame. The adjustable down force controller may be a hydraulic down force controller 30 or a spring down force controller 40. The parallelogram assembly has a height range 95. Figures 2A and 2B show side views 210 220 of a hydraulic version at minimum and maximum heights respectively, and Figures 2C and 2D show side views 230 240 of a spring version at minimum and maximum heights respectively. [0033] In this embodiment the tillage apparatus is a double disk opener. The mounting assembly including a mounting portion 11 for mounting to a towing beam 1. The towing beam may be a square or diamond beam, or a beam with some other predefined profile. Figures 2A to 2D illustrate the location of various towing beams of a towing implement on which multiple individual tillage units (not shown to improve clarity) can be mounted. Figure 7 is an isometric view of multiple tillage apparatus mounted to a multiple towing beams of a towing implement. The ground engaging assembly 60 is attached to the support frame 50 via a forward arm 63. The ground following assembly 70 includes a ground following member 75, which travels over the ground 96, and is attached to the support frame 50 via a rear arm 73. In this embodiment the ground following member is a press wheel, but other arrangement such as a ball, runner, skid, etc. As will be discussed below the depth control assembly 80 controls the angle of the forward arm 63 with respect to the rear arm 73 so as to control the depth of the coulter disks with respect to the press wheel. These are further illustrated in figures 3A and 3B which provide side and rear views 310 320 of the support frame, a forward arm, and a ground following rear arm, and Figures 3C and 3D which provide side and rear views 330 340 of a first body plate 52 of the support frame 50. The embodiment of the depth control assembly is further illustrated in a close up side view 250 in Figure 2B, and an isometric view 400 in Figure 4. Further components are illustrated in Figure 3E which is a side view 350 of spring pin according to an embodiment, and Figures 3F and 3G which are side and rear views 360 370 of pin plate according to an embodiment. [0034] In this embodiment the double disk opener includes two offset 15" coulter disks 66 67 mounted on stub axles 64 65, onto which the bearings and hubs are mounted, which are attached to a forward arm 63 with a wishbone profile (illustrated in Figure 3B). The hubs may be 6 hole hubs with triple lipped sealed bearings. A single or double sowing boot (not shown) is located between the two disks to place a seed at the opened depth. The coulter disks are plain disks but could be scalloped, or replaced with an opening tyne. [0035] In order to provide a compact arrangement for the tillage apparatus, and thus reduce the overall length of the system shown in Figure 7, the forward arm 63 is angled forward of the vertical, as measured from reference mounting point 62 and when in the normal orientation as shown in Figures 2A to 2D. As shown in Figures 2A and 2C, the forward arm angle 61 is preferably selected to be as large as possible whilst providing clearance between the top of the ground engaging component (ie the top of the coulter 7 disks 66 67) and the lower surface of the mounting assembly 11, so as to locate the ground engaging component under the mounting assembly. For this embodiment the angle 61 is approximately 300. The angle could be varied, for example it could be the range of 25' to 35'. Other angles (eg 45' or more) may be used depending upon the choice of coulter disks or tynes, and materials selected (eg material strength). Using a compact baseline allows the system to perform tighter turns with less stress on components, and less dragging and disturbance of the soil. [0036] The tillage apparatus uses a parallelogram assembly as illustrated in Figures 1, 2A to 2D and isometric view 500 of Figure 5. The parallelogram assembly includes an upper rectangular frame and a lower rectangular frame which are mounted so that a plane containing the upper frame is kept parallel to a plane containing the lower rectangular frame. The upper rectangular frame including a first upper arm 21, a second upper arm 21a, a first upper shaft 24 and a first lower shaft 23. The first upper shaft 24 is located near one end of the first and second upper arms 21 21a and connects the first and second upper arms 21 21a. The first lower shaft 23 is located near the other end of the first and second upper arms 21 21a and connects the first and second upper arms 21 21a to define the upper rectangular frame. Similarly the lower rectangular frame includes a first lower arm 22, a second lower arm 22a, a second upper shaft 26 and a second lower shaft 25, with the second upper shaft 26 located near one end of the first and second lower arm 22 22a and connects the first and second lower arms 22 22a. The second lower shaft 25 is located near the other end of the first and second lower arms 22 22a and connects the first and second lower arms 22 22a to define the lower rectangular frame. [0037] The mounting assembly 10 includes a first plate 12 and a horizontally spaced second plate 12a for supporting a mounting portion 11 for receiving a towing implement mounting beam (or arm) 1. To provide for ease of manufacture and reduced cost of manufacture each of the first and second plates 12 12a include a vertical slot 14 with a centrally located rearward aperture 13 to allow insertion of the first upper shaft and the first lower shaft. Once inserted the upper shaft is located in the upper end of the slot and the lower shaft is inserted in the lower end of the slot. To lock the shafts (and thus frames) in place, a cover plate receiving aperture 15 and a cover plate 16 with upper and lower apertures for receiving the first upper shaft 24 and the first lower shaft 23 is provided. This additionally has a projection which is located or inserted into the cover plate receiving aperture 15 so as to lock the assembly together. This arrangement is shown in detail in close up view 240 of Figure 2A. Further Figure 5 shows an isometric view of the parallelogram assembly in which the upper cover plate has been omitted to more clearly illustrate the slot and shafts. [0038] Similarly the support frame portion includes a first support plate 52 and a horizontally spaced second support plate 56. These are spaced apart using support members (or rods, plates, beams etc) 51 a, 51b and 51c. Each of the first and second support plates 52 56 include a lower vertical slot 54 with a centrally located forward aperture 53 to allow insertion of the second upper shaft 26 and the second lower 8 shaft 25. Once inserted the second upper shaft is located in the upper end of the slot and the second lower shaft is inserted in the lower end of the slot. To lock the shafts (and thus frames) in place, a cover plate receiving aperture 55 and a cover plate with upper and lower apertures for receiving the second upper shaft 26 and the second lower shaft 25 is provided. This additionally has a projection which is located or inserted into the cover plate receiving aperture 55 so as to lock the assembly together. The support members 51b and 51c also act as stops to limit the travel of the upper and lower parallelogram arms (or frames) respectively, and thus restrict the vertical range of the support frame (with respect to the towing beam). [0039] The cover plates can be fastened in place using various fastening means. The projection may be threaded and a nut may be located on the inside to lock the cover plate in place. Other removable fastening arrangements may be used, or alternatively the cover plate could be welded in place. The upper rectangular frame could be assembled prior to insertion in to the slots (for example by welding the upper arms 21 21 a to the upper and lower shafts 23 24, otherwise fastened to ensure the correct spacing between the two arms, and could be assembled in situ. A similar approach could be used for the second rectangular frame. Preferably the shafts (or pins) are hardened components to reduce wear and thus ongoing maintenance. Further it is to be understood that the above embodiment is illustrative only, and that mechanical equivalents of the various components and mounting arrangements could be used to achieved the same or similar functionality. [0040] The adjustable down force controller apparatus may be a hydraulic or spring based and both include an upper mount and a lower mount (31, 32, 41, 42), with the upper mount including a shaft which passes through an aperture in the first upper arm 21 and the second upper arm 21a of the parallelogram assembly, and the lower mount including a shaft which passes through an aperture in the first lower arm 22 and the second lower arm 22a of the parallelogram assembly. Various arrangements could be used depending upon the arrangement of the mount and down force controller. For example a single shaft could be provided which passes through both upper arms and the mount, or two separate shafts could be provided on either side of the mount, each one passing through one of the upper arms and attached to the mount. [0041] Figure 1, 2C and 2D illustrate an embodiment of a spring based down force controller. In this embodiment the controller includes a centrally threaded rod 46 with a bolt head 43 mounted between the upper spring mount 41 and lower spring mount 42. The spring mounts are U shaped mounts. An adjustment nut 44 is fastened to a lock plate 45 and a spring 48 is mounted coaxially with the threaded rod 46 between the lock plate 45 and the lower spring mount 42. Rotation of the bolt head adjusts the location of the lock plate along the threaded rod to control compression of the spring and down force transferred to the support frame. The spring is thus arranged to push the support frame 50 down. This facilitates the application of a large down force with a relatively small spring compared to pulling 9 arrangements which have been used in some prior art arrangements. Further the use of a mechanical screw assembly allows easy adjustment of the compression of the main spring to decrease or increase pressure of both the opening coulters and the press wheel. Downward force can be increased to help cut through stubble residue and in drier conditions penetrate the soil for good seed placement. In this embodiment the spring breakout pressure can be adjusted up to 182kgs (400 lbs) and the unit has 254mm (10") of vertical ground following capability or vertical adjustment range (91). [0042] Figures 2C, 2D and 6 illustrate an embodiment of a hydraulic down force controller. In this embodiment the controller includes a hydraulic cylinder 34 and piston 33 arrangement which is used to control the distance between the upper 31 and lower mount 32 so as to control the down force transferred to the support frame. As shown in Figures 2A, 2B the upper mount 31 is the first upper shaft 24. In this embodiment a U shaped bracket is attached to the top of the cylinder 34 to receive the first upper shaft 24. The lower mount 32 is provided via a shaft which passes through the first lower arm 22, the lower end of the piston 33, and the second lower arm 22a (or two separate shafts could be provided, each attached to the lower mount and each passing through one of the arms 22 22a). The extension of the piston with respect to the cylinder will thus force the support frame downward with respect to the towing beam (or towing implement). An advantage of the use of a hydraulic down force controller is that a control line for the hydraulic cylinder can be provided to allow an operator to remotely monitor and control the down force from the tractor (or other location). [0043] A control line can be provided to the operator in a tractor to allow an operator to remotely control the pressure in the hydraulic unit, and thus down force (or vertical height of the support frame). To further assist an operator a pressure gauge can also be fitted to the hydraulic system to allow the operator to monitor the down pressure from the tractor. In this way the operator driving the tractor from the tractor seat can monitor and rapidly adjust the down force as required and in response to varying soil types and conditions. To further assist an operator to monitor and control the down force, the individual hydraulic units may be connected up to a hydraulic system which controls all of the individual units mounted to a towing beam or towing implement. A central control and monitoring system could then be provided to the operator so as to allow the operator to control all of the tillage units attached to a towing implement at once. This may be in the form of a single control or several controls may be provided each of which controls a group of tillage units (for example all units on a specific towing beam, or geographic area). [0044] To facilitate raising of the tillage unit for transport, a spring return can also be provided. Figure 6 is a top view 600 of the hydraulic spring force controller and further includes a spring 35 which is mounted between the upper and lower mounts 31 32 adjacent the hydraulic unit. The spring exerts a force to draw the mounts towards each other (ie minimise the extension distance) and thus when the pressure in the hydraulic unit is reduced or the hydraulic unit is switched off, the spring force will act to the raise the apparatus off the ground to facilitate transport. A further advantage is that as only the individual tillage 10 units are lifted off the ground, rather than the entire frame which may have 10 or more individual tillage units mounted on it, the lifting mechanism can be kept relatively simple and cheap. In this case, a spring mounted in parallel with the hydraulic unit in each individual tillage unit provides the functionality as compared to more complicated and expensive hydraulic lifter for the entire towing implement. [0045] Different crops require seeds to be sown at different depths, and to maximise the yield it is desirable to ensure uniform sowing of seeds at the depth appropriate to the crop. Thus it is desirable to provide a mechanism for setting the cutting depth of the bottom of the ground opener with respect to the bottom of the press wheel (ie where it contacts the ground) which can be adjusted when changing crops. As there is typically between 10 and 30 individual tillage units being towed, it is desirable that setting of the cutting depth for each tillage unit should be as simple and uniform as possible. [0046] A depth control assembly 80 for controlling the depth of the ground engaging assembly 60 relative to the ground following member (ie press wheel) 75 has been developed which includes a depth selector which allows selection of one of a set of predefined depths of the ground engaging assembly relative to the ground following member (or more specifically a reference point on the ground following member, such as the axle of the press wheel, or lower surface of a skid) within a depth range. The use of a common mechanism with predefined depth settings allows an operator to quickly select a predefined depth. This can then be performed on each individual unit, and the commonality of the design ensures uniform depth placement across all units. [0047] In the embodiment illustrated in Figures 1 to 7, the depth control assembly 80 is a spring pin adjustment system. Figure 4 shows an isometric view 400 of the spring pin adjustment system, Figure 2B shows a close up side view 250 and Figures 3A to 3G illustrated the various components. This system includes a spring pin depth selector which allows selection of 6mm depth increments over a 50mm range. However the size of the increment and actual range could be varied. For example finer control could be obtained using 5mm or 3mm increments or coarser control could be provided using 10mm increments. Similarly the range could be narrowed (eg to 30mm) or extended (eg to 70mm) depending upon the intended crops to be sowed. Figure 2B shows the different depths 95 associated with the different settings 84a-84d and 85a-85d. Each of the apertures could be colour coded or include some other visual indicator such as number or depth value, to assist the user in checking the correct depth has been selected. This allows the user to quickly confirm, such as by a visual inspection, that each unit in the array has been set to the correct (ie intended) depth. [0048] In this system the ground following rear arm 73 is pivotally mounted on a shaft 72 passing through or mounted between the first body plate 52 and the second body plate 56 of the support frame. The forward arm 63 of the ground engaging assembly is fixed to the support frame and this arrangement 11 allows the rear arm of the ground following assembly to pivot with respect to the support frame and thus the ground engaging assembly (and coulter disks). [0049] In this embodiment a pin and a plurality of apertures is used to lock the angle of the rear arm with respect to the support frame. In this embodiment a first set of apertures is provided in the rear arm portion 71 of the first body plate 52 of the support frame 50, and a second set of apertures is provided in a pin plate 86 mounted or fastened on the ground following rear arm 73 (such as by welding). The use of a pin plate provides a close fit (ie no or minimal gap) between the two sets of apertures. In this embodiment four apertures 84a, 84b, 84c, and 84d are provided in the rear arm portion 71 and four apertures 85a, 85b, 85c, and 85d are provided in the pin plate 86. These apertures are provided on a common arc with respect to the pivot point (shaft) 72. The combination of two overlapping sets of apertures provides a compact way to allow selection of a wide range of depths by insertion of a pin or projection into overlapping or coincident apertures. For example in the embodiment shown in side view 250 of figure 2B, the spring pin 83 is inserted through the first aperture 84a of the rear arm portion 71 and the second aperture 85b of the pin plate 86. The maximum depth is thus obtained by overlapping apertures 84a and 85d, and the minimum depth is obtained by overlapping apertures 84d and 85a. [0050] Further each set of apertures are joined using a common channel. This can assist in cleaning the apertures and/or manufacture of the channel. To assist in selection of a depth, a first alignment notch 88 is provided in the edge of the rear arm portion 71, and a second alignment notch 89 is provided in the edge of the pin plate 86. [0051] A spring pin is used to select the depth as shown in side view 350 of Figure 3E. The spring pin is a rectangular section of spring sheet steel to form an arm 82 which is pivotally mounted 81 to the rear arm portion 71 of the first body plate 52. The distal end of the arm 82 includes a projection 83, in this case a pin which is sized to fit into each of the apertures 84a-d and 85a-d. A tab 87 is provided in the distal end (after the pin on the end opposite the pivot) so as to allow removal of the pin from an aperture. The arm, being of resilient spring steel, is designed to provide a biasing force to force (ie engage) and maintain the pin into a selected set (or pair) of apertures. In one embodiment the spring sheet steel is 2mm thick. However other thicknesses may be used provided they retain sufficient resiliency to ensure the pin is maintained in the aperture in use (ie in use it is resistant to popping out due to knocks or other forces that arise during use). [0052] Other embodiments could utilise other arrangements. For example rather than use two overlapping sets of apertures, a single aperture could be provided in one of the plates, and multiple apertures provided in the other (eg one in the rear arm portion 71 and 8 in the pin plate 86 or eight in the rear arm portion 71 and one in the pin plate 86). Other alternatives to the spring pin could be used such as split pins, or nut and bolt fasteners. Further, more complicated arrangements for selecting one of a 12 predefined set of apertures could be provided. For example a dial arrangement could be used such that rotation of the dial causes the pin to be inserted into progressive apertures in a sequence. An automated system could also be used in which a hydraulic or electric motor system moves the rear arm relative to the first body plate 52 in fixed increments, or to move a pin out of an into a set of apertures. Whilst more complicated this would allow depth setting to be centrally controlled such as by an operator on the tractor or towing vehicle. [0053] Embodiments may use standard components such as 380mm (15") high carbon steel coulters, and a 3 80mm (15") press wheel. The ground engaging component may be a double (offset) coulter disk or an opener tyne. A single or double sowing boot may be used. Downward force can be increased to help cut through stubble residue and in drier conditions penetrate the soil for good seed placement. Downward pressure adjustment may be via a manual screw or hydraulic arrangement. The spring breakout pressure can be adjusted up to 182kgs (400 lbs) and the unit has 254mm (10") of vertical ground following capability (ie the vertical adjustment range 91). The overall length from towing beam to rear of the press wheel is relatively compact and between 924mm and 959mm. This is up to 30% shorter than prior art tillage units. An easy to use spring pin can be used to lock the press wheel arm into place, and thus control the depth. Depth can be uniformly varied using 6mm increments over a 50mm travel range. Preferably the tillage apparatus is manufactured from materials such as steel which are both strong and are suitable for use in outdoor environments for extended periods. Hardened components can be used in high load areas (eg shafts 23 24 25 26 of the parallelogram assembly or mounts 31 32 41 42) to extend operational life and reduce ongoing maintenance. [0054] Embodiments described herein provide an improved zero-till tillage apparatus. The double disk opener is robust and can perform well in many different soil types and conditions. Embodiments may use hardened pins in all high load areas to extend operational life and reduce maintenance. The use of a slot arrangement to mount the parallelogram assembly makes manufacture and assembly simpler and cheaper. Individual units can be individually mounted and replaced as required and allow mounting to square or diamond mounting frames. The forward angling of the coulter disk arm provides a compact and unique design, as the press wheel is kept much closer to coulter disk and the sowing boot. This allows tighter turning with less stress on the tillage apparatus and less soil drag. The hydraulic version of the double disc opener features a spring return mechanism for transport and can be conveniently controlled by the driver. Further, the pressure can be adjusted "on the go" from the tractor seat to suit soil types and conditions. The apparatus is a true parallelogram unit so as to allow the opener to follow ground contours providing for more uniform seed placement. The apparatus is versatile and can be used with plain or scalloped coulter disks or tyne openers. The depth control assembly provides an easy, reliable and uniform method for controlling the depth. The use of a spring pin arrangement with fixed increments allows for quick, easy and uniform adjustment of multiple individual tillage units.

13 [0055] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. [0056] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge. [0057] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

Claims (19)

1. A tillage apparatus including: a support frame, a mounting assembly including a mounting portion for mounting to a towing implement; a parallelogram assembly for linking the mounting assembly to the support frame and adapted to allow height adjustment of the support frame relative to the towing implement, and including an adjustable down force controller apparatus to control the down force on the support frame; and a ground engaging assembly attached to the support frame via a forward arm; a ground following assembly including a ground following member attached to the support frame via a rear arm; and a depth control assembly for controlling the depth of the ground engaging assembly relative to the ground following member and a depth selector which allows selection of one of a set of predefined depths of the ground engaging assembly relative to the ground following member within a depth range, wherein the rear arm is mounted on a shaft passing through the support frame and the depth control assembly includes a pin and a plurality of apertures to lock the angle of the rear arm with respect to the support frame.

2. The apparatus as claimed in claim 1, wherein the depth control assembly controls the angle of the forward arm with respect to the rear arm.

3. The apparatus as claimed in claim 1, wherein forward arm is angled forward of the vertical so as to locate the ground engaging component under the mounting assembly.

4. The apparatus as claimed in claim 3, wherein the angle is selected to be as large as possible whilst providing clearance between the ground engaging component and mounting assembly.

5. The apparatus as claimed in claim 3, wherein the angle is in the range of 25' to 35'.

6. The apparatus as claimed in claim 1, wherein the ground engaging component is a double disk opener.

7. The apparatus as claimed in claim 1, wherein the parallelogram assembly includes an upper rectangular frame and a lower rectangular frame which are mounted so that a plane containing the upper frame is kept parallel to a plane containing the lower rectangular frame, the upper rectangular frame including a first upper arm, a second upper arm, a first upper shaft and a first lower shaft, the first upper shaft located near one end of the first and second upper arm and connecting the first and second upper arms, and the first lower shaft located near the other end of the first and second upper arms and connecting the first and second unner arms to define the unner rectangular frame: 15 the lower rectangular frame including a first lower arm, a second lower arm, a second upper shaft and a second lower shaft, the second upper shaft located near one end of the first and second lower arm and connecting the first and second lower arms, and the second lower shaft located near the other end of the first and second lower arms and connecting the first and second lower arms to define the lower rectangular frame; and the mounting assembly includes a first plate and a horizontally spaced second plate for supporting a mount for receiving a towing implement mounting beam, and each of the first and second plates including a vertical slot with a centrally located rearward aperture to allow insertion of the first upper shaft and the first lower shaft, a cover plate receiving aperture, and a cover plate with upper and lower apertures for receiving the first upper shaft and the first lower shaft, and a projection which is located cover plate receiving aperture; and the support frame portion includes a first support plate and a horizontally spaced second support plate, and each of the first and second support plates including a vertical slot with a centrally located forward aperture to allow insertion of the second upper shaft and the second lower shaft, a cover plate receiving aperture, and a cover plate with upper and lower apertures for receiving the second upper shaft and the second lower shaft, and a projection which is located cover plate receiving aperture.

8. The apparatus as claimed in claim 7, wherein the adjustable down force controller apparatus includes an upper mount and a lower mount, the upper mount including a shaft which passes through an aperture in the first upper arm and the second upper arm of the parallelogram assembly, and the lower mount including a shaft which passes through an aperture in the first lower arm and the second lower arm of the parallelogram assembly.

9. The apparatus as claimed in claim 7, wherein the adjustable down force controller apparatus is a spring based down force controller including a centrally threaded rod with a bolt head mounted between the upper spring mount and lower spring mount with a bolt head, and an adjustment nut fastened to a lock plate, and a spring mounted coaxially with the threaded rod between the lock plate and the lower spring mount, wherein rotation of the bolt head adjusts the location of the lock plate along the threaded rod to control compression of the spring and down force transferred to the support frame.

10. The apparatus as claimed in claim 7, wherein the adjustable down force controller apparatus is a hydraulic apparatus to control the distance between the upper and lower mount so as to control the down force transferred to the support frame.

11. The apparatus as claimed in claim 10, wherein the adjustable down force controller apparatus includes a pressure gauge and a control line to allow an operator to remotely monitor and control the down force. 16

12. The apparatus as claimed in claim 10, wherein the adjustable down force controller apparatus further includes a spring is located between the upper and lower mount so as to provide a spring return mechanism to allow raising of the apparatus off the ground.

13. The apparatus as claimed in claim 1, wherein the support frame includes a first body plate that includes a first set of apertures, and the rear arm includes a second set of apertures.

14. The apparatus as claimed in claim 13, wherein the rear arm further includes a pin plate mounted on the rear arm, and the second set of apertures are located in the pin plate.

15. The apparatus as claimed in claim 1, wherein the pin is mounted in a spring arm which is pivotally mounted to the support frame, wherein the spring arm provides a biasing force to force the pin in an aperture.

16. The apparatus as claimed in claim 15, wherein the spring arm includes a tab on the end opposite the pivot so as to allow removal of the pin from an aperture.

17. The apparatus as claimed in any one of claims 1, or 13 to 14, wherein the depth selector is hydraulically adjustable.

18. The apparatus as claimed in any preceding claim, wherein the ground following member is a press wheel.

19. An apparatus substantially as herein described with reference to any one of the embodiments illustrated in the accompanying drawings.