AU2015213369B2

AU2015213369B2 - A plough

Info

Publication number: AU2015213369B2
Application number: AU2015213369A
Authority: AU
Inventors: Gavan Monk
Original assignee: Oregon House Pty Ltd
Current assignee: Oregon House Pty Ltd
Priority date: 2015-08-13
Filing date: 2015-08-13
Publication date: 2021-04-22
Anticipated expiration: 2035-08-13
Also published as: AU2015213369A1

Abstract

In one aspect there is disclosed a plough that includes a support frame, a plurality of gangs of discs, two or more wheel assemblies, a drive systems that rotates the gangs about respective vertical axes and a lock system. The lock system retains each gang at a selected angle of rotation relative to a longitudinal axis of the support frame. The system comprises a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang. Another aspect discloses a locking system for retaining gangs of discs at a selected angle of rotation. A further aspect disclosed is a method of operating a locking system. 6797189_1 (GHMatters) P100615.AU LEANNE 13/08/15 Figure 5 zUOClerm AUN0C6 N AUoscif

Description

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APLOUGH

TECHNICAL FIELD The present invention relates to ploughs for agriculture. More particularly, the invention relates to ploughs that have tilling instruments, such as gangs of discs, which are linked to a frame to move between a ploughing position and a transport position.

BACKGROUND ART To improve the ease of transporting ploughs, for example through narrow gates and on roads subjects to width restrictions on vehicles, conventional plough designs enable tilling instruments, such as gangs of discs, to be moved between a working or ploughing position and a transport or carrying position.

In the working position, the tilling instruments are spread to define a cutting width that is generally wider than the width of the tractor towing the plough to optimise ploughing efficiency. In other words, a plough having broad working width is preferable in order to reducing the number of passes required to plough a field. In the transport position, the tilling instruments are retracted. In the retracted position the tilling instruments are folded close to the frame, on which the tilling instruments are mounted, to minimise the draft width of the plough. The transport position therefore allows the plough to fit through gates that are narrower than the cutting width. Additionally, the plough may be sufficiently narrow in the transport position so that the width of the plough is less than width restrictions for vehicles that travel on roads. This avoids the necessity to obtain special permits to travel on roads, avoids the need to travel in a convoy with lead and trailing vehicles alerting other road users to the oversize load and travel being restricted to specific roads at low-traffic times.

One form of plough has support arms that extend from a central frame and that carry gangs of discs. The arms are linked to the frame to swing between a transport position and a working position. A set of wheels supports the arms.

Movement of the arms between the transport position and the working position may be controlled manually. However, this is a generally inconvenient and time consuming task. It is particularly problematic in the event that the angle of attack of the gangs of discs must be changed each time the terrain or soil conditions change during the course of working a field because a farmer must stop the plough and make the required changes manually. Additionally, the gangs need to be rotated in a specific order so that one gang does not interfere with another gang rotating to its required position. The sequencing arises because the rotational axes of the gangs are relatively close, so that the overall width of the plough in the transport position does not exceed vehicle width restrictions for roads, and because the gangs, in their ploughing position, need to overlap slightly along a central axis of the plough to ensure that soil between the rotational axes of the gangs is also ploughed.

The problem associated with manual movement of the tilling instruments is overcome by providing a hydraulic ram to move the tilling instruments and by enabling the hydraulic ram to be controlled remotely from the cab of a tractor. Typically, ploughs with multiple swing arms have at least two hydraulic rams that control the movement of the swing arms. Accordingly, as disclosed in international application PCT/AU2006/001484 (the contents of which are incorporated herein by reference), in the name of the same applicant as the subject application, a link system connects the gangs of discs to the hydraulic ram. Figures 7 and 8 show the link system in isolation. It comprises a single hydraulic ram to which four gangs of discs are linked through link rods and cams so that actuation of the hydraulic ram causes all four gangs of discs to move at once. The link system disclosed in PCT/AU2006/001484 is remotely actable from a cab of tractor coupled to the plough. Remote actuation is a safety measure because it ensures that the worker is remote from the plough when the gangs are rotated.

The link system enables all of the gangs to rotate simultaneously and so that the respective gangs do not interfere with each other during rotation to a new angle of attack or rotation to the ploughing position or transport position. Furthermore, the link system enables the angle of attack to be adjusted to a variety of angles between the transport position and a fully extended ploughing position. In terms of reducing time required to adjust the plough for different terrain or soil conditions, the simultaneous movement of all gangs and the control of the gangs from the cab of the tractor makes the link system very effective in reducing manual input to working the plough.

The applicant has, however, developed an improved alternative plough that still provides the benefits outlined above. In particular, the applicant is concerned with reducing the downtime of a plough associated with adjusting the tilling instruments between the transport position and the ploughing position and to different angles between those positions.

The above references to the background art, including references to conventional ploughs, do not constitute an admission that the art or ploughs form a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the plough disclosed herein.

SUMMARY OF THE DISCLOSURE In a first aspect there is disclosed a plough including:

(a) a support frame having a longitudinal axis and a draw bar at a forward end thereof for coupling the plough to a towing vehicle;

(b) a plurality of gangs of discs, each gang being independently coupled to the support frame for pivotable movement about a substantially vertical axis which enables the gangs of discs to be pivoted between a transport position in which the gangs of discs are arranged substantially parallel to the longitudinal axis to provide the plough with a minimum draft width and a ploughing position in which the gangs of discs are arranged for ploughing;

(c) two or more wheel assemblies, each assembly including one or more wheels mounted to legs which are linked to the support frame to enable adjustment of the vertical position of the wheels relative to the support frame;

(d) a drive system that rotates the gangs about their respective substantially vertical axes between the transport position and the ploughing position, the drive system being actuable remotely of the plough; and

(e) a lock system that retains each gang at a selected angle of rotation relative to the longitudinal axis, the lock system comprising a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang; and

wherein the second lock is mounted on the gang to define an arcuate path on rotation of the gang and the second lock is mounted in proximity to the support frame so that actuation of the second lock causes it to clamp the gang to the support frame.

The term "ploughing position" as used throughout this specification, including the claims, is taken to mean a range of positions that the gangs of discs may adopt for the purposes of operating the plough. More specifically, the range of positions are the different angles of attack that the gangs can adopt.

The second lock may be mounted to the gang so that it secures the gang to the support frame. Optionally, the second lock is a clamp that secures the gang to the support frame. Optionally, the first lock and the second lock are manual. According to an alternative option, the first lock is manual and the second lock is remotely actuable.

The first lock may include a pin and a series of separate seats formed in the support frame to receive the pin so that it extends into the rotational path of the gang at a desired angle of rotation for the gang and wherein the seats are spaced apart so that each seat is associated with a different desired angle of gang rotation.

The support frame includes an arcuate member adjacent the second lock, the arcuate member having a radius of curvature slightly less than the arcuate path of the second lock so that the second lock remains in proximity to the arcuate member at each of the different desired angles of gang rotation.

The second lock may be formed by a generally vertically oriented clamp plate that is pivotally mounted to a top side of each gang by a mounting plate so that the clamp plate can rotate in a generally vertical plane.

The clamp plate and the mounting plate may be located adjacent to the arcuate member so that the clamp plate overlaps the arcuate member.

The mounting plate may include outwardly extending wings to which are mounted support rollers that overlap the arcuate member and are configured to roll along a track on the actuate member to support the gangs in close proximity to the curved platform.

The second lock may include a hydraulic ram which is operable to cause the clamp plate to rotate in the vertical plane about its pivot mounting to the mounting plate to push down on the arcuate platform.

The second lock may include a lever pivotably mounted to an upper portion of the clamp plate and which causes the clamp plate to clamp the gang to the arcuate platform when the level is rotated downwardly relative to the pivot connection.

The seats of the first lock may be formed in the arcuate member.

The drive system may include a first hydraulic ram for each respective gang and wherein each first hydraulic ram extends between the support frame and the respective gang.

The drive system may include timing valves that are configured to operate the first hydraulic rams sequentially so that the gangs do not interfere with each other when rotating.

The drive system may be remotely actuable.

In a second aspect, there is disclosed a locking system for retaining gangs of discs, that is mounted to about a substantially vertical axis to a support frame of a plough to enable displacement along a rotational path to a selected angle of rotation relative a longitudinal axis of the plough, the locking system to including a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang

caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang and wherein the second lock is mounted on a gang to define an arcuate path on rotation of the gang and the second lock is mounted in proximity to the support frame so that actuation of the second lock causes it to clamp the gang to the support frame.

In a third aspect, there is disclosed a method of adjusting an angle of rotation of a gang of discs mounted to a plough about a substantially vertical axis, the angle of rotation being controlled by actuation of a drive system linked to the gang and by a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang

caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang, the method including:

(a) unlocking the second lock;

(b) adjusting the position of the first lock to stop the gangs at the new angle of rotation;

(c) operating the drive system so that the gang rotates until it abuts the first lock; and

(d) locking the second lock.

Steps (a), (c) and (d) may be performed by remote actuation of the drive system and the second lock.

The first lock may include a pin and a series of separate seats formed in a support frame of the plough to receive the pin so that it extends into the rotational path of the gang at a desired angle of rotation for the gang, the seats are spaced apart so that each seat is associated with a different desired angle of gang rotation and wherein step (b) includes manually adjusting the position of the first lock by placing it in a different seat.

BRIEF DESCRIPTION OF THE DRAWINGS Notwithstanding any other forms which may fall within the scope of the apparatus and method as set forth in the Summary, a specific embodiment will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a top plan view of a plough in accordance with an embodiment of the present invention with gangs of discs configured in one ploughing position.

Figure 2 is a front plan view of the plough in Figure 1 with the gangs of discs configured in the same ploughing position.

Figure 3 is an underside view of the plough in Figure 1 with the gangs of discs configured in the same ploughing position.

Figure 4 is a left side elevation of the plough in Figure 1 with the gangs of discs configured in the same ploughing position.

Figure 5 is a top plan view of a plough in Figure 1 with gangs of discs configured in the transport position.

Figure 6 is an underside view of the plough in Figure 5 with gangs of discs configured in the transport position.

Figure 7 is a photo of a second lock in accordance with an embodiment of the present invention. The second lock in this photo is a manual embodiment of the second lock and is in the locked position.

Figure 8 is a photo of the second lock in Figure 4 in the unlocked position.

Figure 9 is a photo of a second lock in accordance with an embodiment of the present invention. The second lock in this photo is a remotely actuated embodiment of the second lock and is in the locked position.

Figure 10 is a photo of the second lock in Figure 6 in the unlocked position.

DESCRIPTION OF EMBODIMENT An embodiment of the present invention is illustrated in Figures 1 to 10 in the form of a plough 10.

The plough comprises a frame 20 (Figures 1 and 2) with a draw bar 22 and gangs of discs 30, 40 pivotably mounted to the support frame at pivots 32, 34, 42 and 44. The plough 10 further comprises wheel assemblies 50 (Figures 1, 2, 4 and 5) for supporting the frame 20.

The plough 10 further comprises driving means for moving the gangs of discs between a ploughing position and a carrying position. The driving means is in the form of a hydraulic rams 70 (Figures 1 and 3) which link the gangs of discs 30, 40 to the frame 20 so that extension and retraction of the hydraulic rams 70 causes rotational movement of the gangs of discs 30, 40 about their respective pivots 32, 34, 42 and 44. The hydraulic rams 70, therefore, are used to position the gangs of discs 30, 40 at the ploughing position where the gangs of discs 30, 40 have one of a range of different angles of attack. The hydraulic rams 70 are also used to rotate the gangs of discs 30, 40 to the transport position (Figure 5) from ploughing position and back.

The frame 20 is a generally elongate and is formed of three primary, longitudinal tubular steel beams spaced apart by studs to form a rigid structure for supporting the gangs of discs 30, 40 during transport in a carrying position and during ploughing in the plough position. The draw bar assembly 22 is located at a forward end of the plough 10 for connection to a vehicle, such as a tractor, for towing the plough.

The gangs of discs 30, 40 are preferably similar to those disclosed in Australian patent no. 552035 (the content of which is incorporated herein by this reference) and, therefore, are not described here in detail.

The wheel assemblies 50 include wheels 51 mounted on legs 52 that are connected to the frame 20 by respective pivots 56. The legs 52, therefore, are able to rotate about the pivots 56 in a vertical plane that is parallel to a longitudinal axis of the frame 20. The legs 52 are also connected to the frame 20 hydraulic rams (not shown) that control the extent to which the legs are pivoted. The wheel assemblies 50, therefore, vary the vertical position of the wheels 51 with respect to the support frame 20. Accordingly, adjustment of the wheel assemblies 50 to a position in proximity to the frame 20 causes the gangs of discs 30, 40 to come into contact with the ground on which the plough 10 is located. Conversely, adjustment of the wheel assemblies 50 so that they are remote from the frame 20 causes the gangs of discs to be lifted above the ground such that the plough 10 can be transported, for example on roads or from field to field.

Naturally, the position of the wheel assemblies 50 relative to the frame 20 can be selected to be a position between the extreme positions to control the depth to which the gangs of discs 30, 40 penetrate the soil. In those positions, the wheel assemblies 50 travel in contact with the ground being ploughed and support the frame 20.

The gangs of discs 30, 40 are pivotably mounted to the frame 20 at a location longitudinally offset from the centre of the gang of discs 30, 40 to define a short end 36, 46 and a long end 38, 48 of each gang of discs 30, 40. The hydraulic rams 70 connect to the short ends 36, 46 of the gangs 30, 40 such that, when the gangs of discs 30, 40 pivot from a carrying position to a ploughing position the short ends 36, 46 rotate inwardly towards a longitudinal centre line of the plough 10 and the long ends 38, 48 swing outwardly from the frame 20.

The width of the plough 10 can be reduced by ensuring that the short ends 36, 46 extend inwardly toward the longitudinal centreline axis of the plough 10 of the frame 20. The gangs of discs 30 comprising the forward gangs of discs 30 are longitudinally offset along the frame 20 to avoid interference between the gangs of discs 30 when pivoting from the carrying position to the ploughing position and vice versa (Figure 3). For the same reason, the gangs of discs 40 of the rearward gangs of discs are also longitudinally offset along the frame 20.

Additionally, the hydraulic rams 70 are connected to hydraulic fluid lines that include sequence valves (not shown). The sequence of rotating the gangs 30, 40 from the transport position to the ploughing position is controlled by the sequence vales to ensure that they do not interfere with each other.

The frame 20 includes an arcuate member in the form of a curved platform 60 associated with each pivot 32, 34, 42 and 44. The platform 60 has an outer edge with a constant radius curve which is centered on the respective pivots 32, 34, 42 and 44. Along the upper side of the outer edge of the platform 60 is located a track 68.

The plough 10 includes a first lock (Figures 9 and 10) and a second lock (Figures 7 to 10) for each gang 34, 40 and which are operable to secure each gang at a selected angle of attack.

The first lock includes a series of six holes 62 which are disposed radially inwardly from the track 68 and which pass through the platform 60. The holes 62 are equally spaced along an outer extent of the platform 60 in the region that the gangs of discs 30, 40 are located for different angles of attack.

The first lock further includes a pin in the form of a bolt 66 which loosely fits in the holes 62 and extends through the platform 60 into the path defined by the gangs 30, 40 as they rotate about the pivots 32, 34, 42 and 44. In this way, the bolt 66 is able to abut the gang 30, 40 and arrest further rotational movement about the pivots 32, 34, 42 and 44. In this regard, the bolt 66 is located on the trailing side of the gangs 30, 40 so that rotational torque on the gangs 30, 40 caused by drag imparted during operation of the plough 10 is counteracted.

The plough 10 further includes a second lock which is formed by a generally vertically oriented clamp plate 72 mounted to a top side of each gang 30, 40 by a mounting plate 74. The clamp plate 72 is pivotably mounted to the mounting plate 74 so that it can rotate in a generally vertical plane. The clamp plate 72 and mounting plate 74 are located on the gangs 30, 40 adjacent to the curved platform 60 so that the clamp plate 72 overlaps the curved platform 60. The mounting plate 74 includes outwardly extending wings 76 to which are mounted support rollers 78 that also overlap the curved platform 60 and are configured to roll along the track 68 to support the gangs 30, 40 in close proximity to the curved platform 60.

In one form shown in Figures 9 and 10, the second lock includes a hydraulic 5 ram 80 extending from an upper part of the clamp plate 72 to the gangs 30,40 so that actuation of the hydraulic ram 80 causes the clamp plate 72 to rotate in the vertical plane about its pivot mounting to the mounting plate 74 to push forcibly down on the curved platform 60. The force applied by the hydraulic ram 80, once the clamp 72 is in contact with the curved platform, will pull the gangs 30, 40 upwardly to contact an underside of the curved platform 60, thereby clamping the gangs 30, 40 to the curved platform 60.

In an alternative form shown in Figures 7 and 8 the second lock includes, in place of the hydraulic ram 80, a lever 84 pivotably mounted to an upper portion of the clamp plate 72 and extending rearwardly therefrom. This form of the second lock further includes a fixed-length spacer bar 82 that extends from the gangs 30, 40 to a point on the lever 84 adjacent to the position at which the lever 84 is pivotably mounted to the upper part of the clamp plate 72. This configuration causes the clamp plate 72 to clamp the gangs 30, 40 to the curved platform 60 when the lever 84 is rotated downwardly relative to its pivot connection to the clamp plate 72, whereby the spacer bar 82 pushes the clamp plate 72 about its pivot mounting to the mounting plate 74 and into contact with the curved platform 60.

The spacer bar 82 includes a forked end 86 with respective aligned holes passing through each side of the forked end 86. A fixing pin 88 is passed through the holes when the lever 84 has been actuated to clamp the gangs 30, 40. In this position, the spacer bar 82 is generally parallel with the lever 84 so that there is a clear path between the holes in the forked end 86 on an underside of the spacer bar 82 so that the fixing pin 88 can be passed through the aligned holes, thereby locking the lever 84 to the spacer bar 82. Consequently, the second lock is actuated and clamps the gangs 30, 40 to the curved platform 60.

The curved platform includes a further hole 64 toward an end of the curved platform 60 opposite to the holes 62. The hole 64 performs the same function as the holes 62, but is utilised for receiving the bolt 66 when the gangs 30, 40 are in their respective transport position so as to prevent inadvertent rotation of the gangs 30, 40 out of their transport position during transport. The same applies to the second lock which may also be actuated when the gangs 30, 40 are located in their transport position.

Forming the first lock so that it interferes with the rotation of the gangs 30, 40 and forming the second lock so that it does not interfere with rotation of the gangs 30, 40 means that a worker need only get out of the cab of the towing vehicle once to change the angle of attack when the second lock includes the hydraulic ram 80 because operation of the second lock can be carried out remotely from the plough 10, typically in the cab of the towing vehicle.

More specifically, changing from one angle of attack of the gangs 30, 40 to another angle of attack involves remotely actuating the second lock to release the clamp plates 72 and then exiting the cab to manually relocate the bolts 66 in holes 62 corresponding to the newly selected angle of attack. The worker then returns to the cab to actuate the hydraulic rams 70 thereby causing the gangs 30 and 40 to rotate to the newly selected angle of attack at which point the gangs 30, 40 abut the bolts 66. The second lock is then remotely actuated to clamp the clamping plate 72 on the curved platform 60.

The time saved by having the worker exit the cab of the towing vehicle only once is very considerable compared to making manual adjustments on two or more separate occasions and returning to the cab between each manual adjustment. The applicant has found that, while locking mechanisms that extend into the path of the gangs 30, 40 provide good security, the combination of their manual operation and the remote operation of the gangs from the cab for safety reasons means that considerable time is spent moving between the plough 10 and the towing vehicle and is spent performing the manual adjustments. The reduced time for adjusting the angle of attack will provide greater impetus for farmers to adjust the angle of attack more frequently to the optimal angle based on the soil conditions and terrain. This includes making small adjustments that will provide improved soil conditions for crop cultivation.

In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus and method as disclosed herein.

Claims

1. A plough including:

(a) a support frame having a longitudinal axis and a draw bar at a forward end thereof for coupling the plough to a vehicle;

2. The plough defined in claim 1, wherein the second lock is mounted to the gang so that it secures the gang to the support frame.

3. The plough defined in claim 1 or claim 2, wherein the second lock is a clamp that secures the gang to the support frame.

4. The plough defined in any one of the preceding claims, wherein the first lock and the second lock are manual.

5. The plough defined in any one of claims 1 to 3, wherein the first lock is manual and the second lock is remotely actuable.

6. The plough defined in any one of the preceding claims, wherein the first lock includes a pin and a series of separate seats formed in the support frame to receive the pin so that it extends into the rotational path of the gang at a desired angle of rotation for the gang and wherein the seats are spaced apart so that each seat is associated with a different desired angle of gang rotation.

7. The plough defined in any one of the preceding claims, wherein the support frame includes an arcuate member adjacent the second lock, the arcuate member having a radius of curvature slightly less than the arcuate path of the second lock so that the second lock remains in proximity to the arcuate member at each of the different desired angles of gang rotation.

8. The plough defined in claim 7, wherein the second lock is formed by a generally vertically oriented clamp plate that is pivotally mounted to a top side of each gang by a mounting plate so that the clamp plate can rotate in a generally vertical plane.

9. The plough defined in claim 8, wherein the clamp plate and the mounting plate are located adjacent to the arcuate member so that the clamp plate overlaps the arcuate member.

10. The plough defined in claim 7 or claim 8, wherein the mounting plate includes outwardly extending wings to which are mounted support rollers that overlap the arcuate member and are configured to roll along a track on the actuate member to support the gangs in close proximity to the curved platform.

11. The plough defined in any one of claims 8 to 10, wherein the second lock includes a hydraulic ram which is operable to cause the clamp plate to rotate in the vertical plane about its pivot mounting to the mounting plate to push down on the arcuate platform.

12. The plough defined in any one of claims 8 to 10, wherein the second lock includes a lever pivotably mounted to an upper portion of the clamp plate and which causes the clamp plate to clamp the gang to the arcuate platform when the level is rotated downwardly relative to the pivot connection.

13. The plough defined in any one of claims 7 to 12, wherein the seats of the first lock may be formed in the arcuate member.

14. The plough defined in any one of the preceding claims, wherein the drive system includes a first hydraulic ram for each respective gang and wherein each first hydraulic ram extends between the support frame and the respective gang.

15. The plough defined in claim 9, wherein the drive system may include timing valves that are configured to operate the first hydraulic rams sequentially so that the gangs do not interfere with each other when rotating.

16. The plough defined in any one of the preceding claims, wherein the drive system is remotely actuable.

17. A locking system for retaining a gang of discs, that is mounted to about a substantially vertical axis to a support frame of a plough to enable displacement along a rotational path to a selected angle of rotation relative a longitudinal axis of the plough, the locking system including a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang and wherein the second lock is mounted on a gang to define an arcuate path on rotation of the gang and the second lock is mounted in proximity to the support frame so that actuation of the second lock causes it to clamp the gang to the support frame.

18. A method of adjusting an angle of rotation of a gang of discs, that is mounted to a plough about a substantially vertical axis, the angle of rotation being controlled by actuation of a drive system linked to the gang and by a first lock that intersects the rotational path of the gang to counteract rotational torque on the gang caused by drag during operation of the plough and a second lock that is independent from the first lock and which secures the gang at the selected angle of rotation and is free of the rotational path of the gang, the method including:

(a) unlocking the second lock;

(d) locking the second lock.

19. The method defined in claim 18, wherein steps (a), (c) and (d) are performed by remote actuation of the drive system and the second lock.

20. The method defined in claim 18 or claim 19, wherein the first lock includes a pin and a series of separate seats formed in a support frame of the plough to receive the pin so that it extends into the rotational path of the gang at a desired angle of rotation for the gang, the seats are spaced apart so that each seat is associated with a different desired angle of gang rotation and wherein step (b) includes manually adjusting the position of the first lock by placing it in a different seat.