GB2640580A

GB2640580A - A coupling device for a tractor and a trailing implement

Info

Publication number: GB2640580A
Application number: GB2405889.3A
Authority: GB
Inventors: Martin Lole Christopher
Original assignee: Greentec AS
Current assignee: Greentec AS
Priority date: 2024-04-26
Filing date: 2024-04-26
Publication date: 2025-10-29
Also published as: GB202405889D0

Abstract

A coupling device 40 for coupling a powered trailing implement such as a rotary mower 10 to a tractor 2 wherein the tractor has a pair of link arms 6 that are connected to the device. The coupling device has at least two leg members 44, each configured to be attachable to a link arm 6 of the tractor, a crossbar 42 extending between the leg members and an arm 43 extending rearwardly from the crossbar and being pivotably attached thereto, the arm being configured to be fixedly secured to the trailing implement 10. A single driveline shaft 14 extends from the tractor to the trailing implement and the pivot point 46 of the coupling device lies substantially mid-way along the single driveline shaft. The invention addresses potential issues such as positioning relative to turning requirements, guard damage and allowing the use of a cardan joint.

Description

A Coupling Device for a Tractor and a Trailing Implement.

Field of the Invention.

The present invention relates generally to agricultural apparatus, and more particularly to an improved coupling device for a trailing implement, especially a trailing rotary mower that is trailed behind a tractor.

Background

It is common practice to tow agricultural implements, such as rotary mowers including rotary wing (flex wing or batwing) mowers behind a tractor. The implements receive power via a driveline shaft connected to a power take off (PTO) shaft of the tractor. The power shafts are normally connected via constant velocity joints and the implement is pivotally attached to the rear of a tractor by the tractor drawbar, discussed in further detail below in relation to Figures 1A and 1B of the accompanying drawings.

The wings are included so that they can be raised for ease of transport. It is common for the extended width of the machines (that is, with wings lowered) to be in the region of 5 to 8m in width but the machines should be less than 3m to enable transportation on roads. Due to the layout of the machines it is impractical to have a multi PTO shaft arrangement. In this respect, the multi rotors are usually mounted to a gearbox and each of the rotor gearboxes are connected via driveshafts to a central gearbox that is mounted to the front of the machine.

To date, all trailed mowers are trailed via the drawbar hitch on the tractor whether it's a hitch below the PTO shaft or a hitch above the PTO shaft. This type of hitching presents a number of problems, the first problem being that the hitch is within the footprint of the tractor, i.e. when looking at the direction of travel the hitch is front of the lower link hitching point. This puts the pivot much closer to the PTO yoke at the tractor engine, and accordingly, at a much further distance from the yoke at the gearbox end of the PTO shaft. 1.

This positioning of the pivot can create problems when using a standard single cardan joint at each end of the PTO shaft. It is important that angles at each end of the shaft are small and as equal as possible. However, as shown in Figure 1C, the positioning of the pivot much closer to the PTO yoke means that the angles Al and A2 are not equal, and nor are lengths Ll and L2.

Typically the joint angles should not exceed 35 degrees under power. If the angle exceeds 35 degrees up to a maximum of 45 degrees whilst rotating, the PTO drive must be disengaged to turn the implement. Failure to do so would damage the single cardan joint. This is normally addressed by fitting a constant velocity joint (CV). A CV joint will allow the machine to continue to operate for brief periods whilst turning. However, CV joints are very expensive, heavy and often finger trapping when fitting.

Another common problem associated with attaching trailed mowers via the drawbar hitch on the tractor arrangement is that the rear link arms of the tractor when turning are constantly at risk of hitting the drive shaft. In doing so, damage may occur to the guards and the shield surrounding the driveshaft. These guards must be replaced quickly to comply with safety regulations but their replacement is very costly and time-consuming. Equally as likely, the telescopic tubes of the PTO shaft may be damaged which means the complete PTO shaft should be replaced. Damage to the tubes is also likely to cause damage to the shaft, the tractor PTO/gearbox shafts, their bearings or their oil seals resulting in an extremely expensive repair.

Thus, the conventional manner of attaching a powered trailing implement to a tractor clearly suffers from some significant drawbacks. The attachment of the hitch of the implement to the drawbar of the tractor results in the pivot point between the two vehicles being close to the tractor. This means that a constant velocity joint must be installed on the tractor end of the driveline shaft to accommodate tight turning angles. Furthermore, the link arms of the tractor remain exposed. This often causes the arms to collide with parts of the trailing implement when turning the tractor. This is particularly problematic if an arm collides with a guard that surrounds and shields the drive shafts. These guards must be replaced immediately if damaged due to safety regulations but are extremely costly to replace.

It is the aim of the present invention to provide an improved coupling device for coupling a tractor with a powered trailing implement, particularly but not exclusively a rotary mower, that overcomes, or at least alleviates, the abovementioned problems.

Summary of the Invention

According to a first aspect of the present invention there is provided a coupling device for connecting a trailing implement to a tractor, the coupling device comprising: at least two leg members each configured to be attachable to a link arm of a tractor; a crossbar extending between the leg members; and an arm extending rearwardly from the crossbar and being pivotably attached thereto, the arm being configured to be fixedly secured to a trailing implement.

The leg members may be formed integrally with the cross bar, for example, wherein the cross bar and leg members are in the form of a substantially n-shaped or U-shaped member. Alternatively, the leg members may be separate components that may be fastened to each end of the cross bar. Suitable fixing means, such as brackets and/or fasteners may be provided to secure each free end of the leg member to a respective link arm of the tractor. Preferably, the leg members are each pivotably mounted to the link arm of the tractor.

The arm is preferably pivotably attached to the crossbar substantially mid-way between the leg members. The arm is preferably attached to the crossbar by at least one joint, the at least one joint providing at least two directional movement, for example up and down movement or side to side movement. More preferably, the arm is attached to the crossbar by one or multiple joints to provide multi directional movement. Preferably, at least one pivot joint is provided to provide sideways movement of the arm with respect to the crossbar. More preferably, the arm is movable about both a vertical and lateral axis, thereby providing both up and down and side to side movement of the arm with respect to the crossbar.

The desired range of movement may be provided with multiple types of joints or, for example by a ball and socket or universal joint. The mounting of the leg members to a link arm of the tractor also allows for the tractor to raise and lower to the ground contour, pitching up and down.

In one embodiment, a housing or bracket is provided that is connected to the arm and is attached to the crossbar about a vertical axis to allow side to side movement. For example, the arm may be connected to a C-shaped bracket that surrounds the crossbar, the bracket being connected to the crossbar via a vertical pin extending between the upper and lower ends of the bracket. Optionally the arm may be attached to the crossbar to also allow a limited degree of up and down movement, for example being hingedly mounted to the housing or bracket or the housing or bracket may be provided with a gap or longitudinal slot to allow a limited range of vertical movement of the arm. The vertical axis provides for sideways movement of the arm with respect to the crossbar. Up and down movement of the arm with respect of the crossbar is optional and may also be provided by the connection between the leg members and the link arms of the tractor.

In an alternative embodiment, a housing may be provided that is fixedly secured to the crossbar and has a socket for a ball joint whereby the joint provides for both sideways and up and down movement of the arm with respect to the crossbar.

The arm is preferably secured to the trailing implement by at least one support member, preferably two support members, extending from the arm and attachable to the front of the trailing implement. Preferably, the support members extend laterally and rearwardly from the arm. It is preferable for the support members to be fixedly secured to the arm, for example, by welding.

In a preferred embodiment, the arm may be telescopically adjustable, for example, the arm may comprise a sleeve mounted on a rod, the sleeve being movable with respect to the rod and being provided with locking means, such as a locking pin, to secure the sleeve in a desired position along the length of the rod. Preferably, the sleeve is attached to the support members and the rod is attached to the crossbar. However, it is to be appreciated that alternative configurations may be provided to provide a telescopic arm, such as a square hollow section within another square hollow section. This enables the positioning of the pivot point to be adjustable forwards and backwards to maintain the pivot substantially central to a shaft length when the coupling device is mounted between the trailing implement and the tractor.

Optionally, a pair of stabilisers may be provided for supporting the coupling device when it is disconnected from the link arms of a tractor. More preferably, each stabiliser comprises a longitudinal prop that is slidably mounted to a part of the coupling device, the stabiliser being securable in a raised and a lowered position. The stabliser may be mounted to an end of the crossbar, each leg member, and/or a support member. For example, each stabiliser may be mounted with respect to the crossbar or leg member by a bracket attached to the crossbar or leg member that surrounds the stabiliser, the bracket having a locking pin for receipt within a recess of the stabiliser wherein the locking pin retains the stabiliser in its raised and lowered positions. Each stabiliser may be provided with a foot at its lower end.

It is to be appreciated that one or more component parts of the coupling device may be formed integrally or the parts may be formed separately and fixed together by suitable fastening means.

Optionally, at least one additional link member may extend from the crossbar or housing for connection to the tractor. For example, a link may extend from the crossbar in an opposing direction to the arm. In particular, an additional link member is preferably provided when the joint between the crossbar and arm is a multidirectional joint, such as a ball joint. The additional link member may extend from the housing attached to the crossbar.

A second aspect of the present invention provides a trailing implement, particularly but not exclusively a rotary mower, the trailing implement fitted with a coupling device according to the first aspect of the present invention.

The trailing implement is powered by the tractor. Preferably, a driveline shaft extends between the tractor and the implement, being connected thereto by non-constant velocity joints (also known as single cardan joints). Preferably the crossbar extends above the driveline shaft. More preferably still, the joint between the arm and the crossbar lies substantially midway along the driveline shaft, i.e. midway between a power take off shaft of the tractor and a drive shaft of the trailing implement.

A third aspect of the present invention provides a tractor coupled to a trailing implement by a coupling device according to the first aspect of the present invention, wherein the tractor has a pair of link arms extending from a rear of the tractor, the link arms being connected to the leg members of the coupling device and a single driveline shaft extends from the tractor to the trailing implement, preferably wherein each end of the driveline shaft has a standard, non-constant velocity joint, and wherein the pivot point of the coupling device lies substantially mid-way between the joints.

The single driveline shaft preferably extends below the coupling device, i.e. with the crossbar positioned above the shaft and the leg members extending downwardly, but it is to be appreciated that the shaft may extend above the coupling device. The coupling device is preferably secured to the tractor by only the two link arms. However, a third link member may be provided extending between the coupling device and the rear of the tractor, preferably extending from substantially the centre of the crossbar of the coupling device.

A fourth aspect of the present invention provides a method of coupling a trailing implement to a tractor, the method comprising the steps of: providing a coupling device according to the first aspect of the present invention; fixedly securing the arm of the device to a front of the trailing implement; pivotably or fixedly mounting each leg member of the device to a respective link arm at a rear of the tractor; and attaching a standard non-constant velocity joint to each end of a driveline shaft, one joint being attached to a power input of the trailing implement and the other joint being attached to a power take off shaft of the tractor, wherein the pivot point of the coupling device lies substantially mid-way between the standard joints.

The trailing implement preferably comprises a rotary mower, such as a flexi-wing or batwing mower. However, it is to be appreciated that the coupling device according to the invention is suitable for connecting other types of trailing implements that are towed by a tractor and powered thereby via a single driveline shaft.

Brief Description of the Drawings

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings in which: Figure 1A is a schematic side view of an example of a flexi-wing rotary mower attached to a tractor via a coupling mechanism according to the prior art; Figure 1B is a schematic top view of Figure 1A; Figure 1C is a schematic drawing of the PTO shaft and joints illustrating unequal angles and lengths using the coupling mechanism according to the prior art; Figure 2A is perspective side view illustrating a coupling device according to one embodiment of the present invention shown attaching a trailing implement in the form of a rotary mower to rear link arms of a tractor; Figure 2B is a top view illustrating the coupling device of Figure 2A; Figure 2C is a side view illustrating the coupling device of Figure 2A; Figure 3 is a schematic diagram illustrating the position of the pivot point when turning a tractor and the trailing implement provided by the coupling device of Figures 2A to 2C; Figure 4A is an isometric view illustrating a dual flexi-wing rotary mower attached to link arms of a tractor via the coupling device shown in Figures 2A to 2C and Figure 3; Figure 4B is a top view of Figure 4A; Figure 4C is a side view of Figure 4A; Figures 5A and 5B illustrate turning of a tractor coupled to a dual flexi-wing rotary mower via the coupling device shown in Figures 2A to 2C and Figure 3; Figure 6A is perspective side view illustrating a coupling device according to another embodiment of the present invention for attaching a trailing implement to rear link arms of a tractor; Figure 6B is a top view illustrating the coupling device of Figure 6A; Figure 6C is a side view illustrating the coupling device of Figure 6A; Figure 7A illustrates a coupling device according to yet another embodiment of the present invention, shown detached from a front part of a rotary motor; and Figure 7B is perspective side view of the coupling device shown in Figure 7A between a front part of single flexi-wing rotary mower and the rear of a tractor (only part of rear of tractor shown for simplicity).

Detailed Description

The present invention provides an improved coupling mechanism for attaching a trailing agricultural implement, particularly but not exclusively, a rotary mower such as a flexi wing mower or batwing mower, to the rear of a tractor.

Rotary mowers (known by various names such as utility mowers, maintenance mowers, batwing mowers and flexi wing mowers) enable mowing of large areas of grass. The rotary mowers are often provided with flexi wings wherein each wing deck may flex up and down individually as the mower passes over undulations in the ground, allowing for an even cut. The wings may also be lifted up off the ground for transport.

Figures 1A and 1B illustrate one example of a dual wing rotary mower 10 attached to the rear of a tractor 2 by a standard hitch and drawbar mechanism according to the prior art. The rear of the tractor has two wheels 3, an axle 4 with a drawbar 5, a pair of link arms 6 and a power take off (PTO) shaft 8. This shaft transfers power from the tractor to the mower 10. The link arms 6 are generally permanently attached to the rear of the tractor and may be moved up and down using a hydraulic system (not shown).

The rotary flexi wing mower 10 is attached to the tractor by a parallel levelling tow hitch 12 coupled to the drawbar 5 of the tractor which provides a pivot point for the implement behind the tractor. A drive line shaft 14 connects the PTO 8 of the tractor with the gearbox and drive shafts (identified collectively as 16 in the figures) of the mower. The illustrated mower has a central deck 18 and two flexi wing decks 20, each provided with rear wheels 22. However, it is to be appreciated that the mower may also be provided with only a single wing deck on one side of the central deck to provide an implement with a smaller mowing width or just the central deck may be provided. A hydraulic ram 24 and parallel linkage 26 is also connected to the axle of the rear wheels to allow the height to be adjusted. Rotating cutting blades (not shown) are provided under to the decks being powered via the gearbox and drive shafts. An appropriate hydraulic hose rack is also provided (not shown) for connection to the tractor.

Joints are provided at each end of the driveline shaft 14 to connect it to the tractor and mower respectively, allowing rotation of the parts. As will be appreciated, the angles between the centre line of the tractor drawbar and the centre line of the implement hitch may be large (greater than 50 degrees) during turning of the tractor. Furthermore, this turning angle is increased due to the pivot point being located much closer to the tractor than the mower (see Fig. 1C). As a result it is necessary to install expensive constant velocity joints 9, 19 at each end of the driveline shaft 14 where it connects to the tractor and the mower. These provide rotational power at various angles, allowing the same output velocity to be provided in relation to the input velocity, independent of the angle they are operated at. This contrasts with most other joints, which may provide a different output velocity at sharper angles even with the same input velocity. Additionally, and crucially, the driveline shaft 14 must be provided with a guard or shield over the shaft and joints to protect the user from injury. It is critical that all rotating parts of both the tractor, drive line shaft and the mower are guarded to prevent death or serious injury.

This type of coupling mechanism is not ideal for its end application. Most notably, the attachment of the mower hitch 12 to the tractor drawbar 5 can easily result in the operator accidentally hitting the tractor link arms 6 when turning the tractor (see arrow A in Figure 1B). This is particularly problematic because it frequently causes damage to the guards and shields of the rotating parts. These parts are extremely expensive to replace and if not repaired or replaced immediately, result in the mower being out of action. Furthermore, the sharp angles at the drawbar pivot point of the tractor necessitate the need for constant velocity joints at each end which are also extremely expensive.

The present invention solves these problems by providing an alternative coupling mechanism between the tractor and trailing implement, such as a rotary mower, which moves the pivot point further from the tractor.

The solution to the problem is firstly to put the towing pivot point (vertical axis y in Figure 2A) approximately, as near as possible to the centre between the two yokes of the driveline shaft 14. This ensures a substantially equal angle for Al and A2 and also provides approximately equal lengths Ll and L2, as shown in Figure 3 illustrating one embodiment of a coupling according to the present invention. This setup is technically correct, particularly for the long life of the PTO shaft and manufacturers guidelines and provides a clear benefit in that there is a big reduction in the cost of the PTO shaft, due to there being no need for a costly CV joint. Furthermore, the shaft is now much lighter and simpler to fit to the tractor output shaft.

Additionally, another advantage provided by a coupling device according to the present invention is that the vertical axis (y in Figure 2A) is moved the vertical axis outside of the footprint of the tractor, meaning that the link arms cannot hit the PTO shaft.

One embodiment of a preferred coupling device according to the present invention is illustrated in Figures 2A to 5B. Figures 2A to 2C illustrate expanded views of the coupling device 40, Figure 3 illustrates the positioning of the pivot point 46 substantially midway between the ends of the shaft 14, Figures 4A to 4C illustrate the coupling device connected to an in-line tractor and mower and Figures 5A and 5B illustrate the coupling device connected to a turning tractor and mower.

Identical features of a tractor 2 and rotary mower 10 already discussed in relation to Figures 1A and 1B are provided with the same reference numerals and only the differences will be discussed in detail. The coupling device 40 according to this embodiment provides for a semi-mounted trailing implement attached to the link arms 6 of the tractor 2 rather than to the drawbar 5. This moves the connection between the tractor and the trailing implement rearwardly by around 20-25cm (8-10 inches) and allows the pivot point 46 to be moved further down the driveline shaft 14.

In further detail, the coupling mechanism 40 comprises a U-shaped member having a crossbar 42 with legs 44 depending from each end. The free ends of the legs 44 are connectable to the end of each link arm 6 on the tractor. In this manner, the crossbar 42 is held above the driveline shaft 14. A central, vertical axis 46 is provided by a vertical pin passing through the crossbar about which a C-shaped bracket or housing 48 is pivotally mounted. A rearwardly extending arm 43 is attached to the bracket 48 to allow side to side movement of the arm about the vertical axis 46. Optionally (not shown) the arm may be attached to the crossbar to also allow a limited degree of up and down movement, for example being hingedly mounted to the housing or bracket. Up and down movement of the arm with respect of the crossbar is optional and may also be provided by the connection between the leg members and the link arms of the tractor. In this manner, the coupling device may for sideways and up and down movement of the trailing implement with respect to the tractor.

The rearwardly extending arm 43 is fixedly secured to the front part of the trailing implement, such as a rotary mower 10, by support members 47. In the illustrated embodiment, the arm 43 is telescopically adjustable, the arm comprising a sleeve and a rod 45, the rod being connected to the housing 48 and the sleeve being slidable with respect to the rod 45. The position of the sleeve with respect to the rod may be selected and locked in a desired position by suitable securing means. Alternatively, other configurations may be provided to allow the length of the arm to be adjustable, such as a square hollow section within another square hollow section.

In a preferred embodiment, and as shown in the figures, the coupling device also includes stabilisers with feet 49 mounted via a bracket to one or each support member 47. These may be fixed in a retracted position when the mower is coupled to the tractor but lowered to contact the ground thereby supporting the coupling device that remains attached to the mower when released from the tractor.

The coupling mechanism 40 overcomes a number of problems associated with the prior art. The use of the link arms 6 of the tractor moves the pivot point 46 between the trailer and the tractor rearwardly. As can be seen most clearly in Figure 2B and Figure 3, the pivot point 46 lies substantially midway between the tractor PTO shaft 8 and the shaft for the gear box of the rotary mower. This positioning significantly reduces the risk of any part of the tractor, in particular the link arms, colliding with and damaging parts of the mower during turning of the tractor. As illustrated by arrow B in Figures 5A and 5B, no parts of the tractor come into contact with the coupling device and rotary mower during normal turning angles of the tractor. This prevents damage occurring to the drive shaft guards. Furthermore, the positioning of the pivot point substantially midway along the driveline shaft reduces the size of the angles A1, A2 (see Figure 3) between the centre line of the tractor drawbar and the centre line of the implement hitch, thereby removing the need to install expensive constant velocity (CV) joints at each end of the driveline shaft. Instead, standard joints 50 may be used at each end of the shaft 14.

Thus, in a preferred embodiment of the invention, the coupling device provides hitching to the lower link arms 6 via a U shape so as to raise the vertical axis pivot (y axis) above the drive shaft 14. The pivot point 46 should be substantially central to the frame. The second part of the pivot is provided on a horizontal axis (z axis on Fig. 2A) allowing the tractor to roll to the left or the right to the direction of travel independently of the machine. A third pivot point (x axis on Fig. 2A) is achieved by the machine mounting pins rotating on the lower link arms 6. This pivot allows for the tractor to raise and lower to the ground contours, pitching up and down. It is preferable for the pivot on the second horizontal axis (z axis) to be adjustable forward and backwards to ensure the vertical axis (y axis) is somewhere central to the PTO shaft length. Once achieved that position can be maintained by a locking pin.

The coupling device enables three individual axes to allow for all movement needed but also for mounting only to the lower link arms. This makes unhitching simple and safe once lowered onto the stabilizers 49.

Figures 6A to 6C illustrate another embodiment of a coupling device according to the present invention. In further detail, the coupling mechanism 400 comprises a crossbar 420 having legs 440 depending from each end. The free ends of the legs 440 are fixedly connectable to the end of each link arm 6 on the tractor to position the crossbar 420 above the driveline shaft 14. The central, vertical axis 460 is provided on the crossbar about which a bracket or housing 480 is pivotally mounted via a pin extending through the crossbar The bracket is connected to a rearwardly extending swing arm 430 that can rotate about the pivot point of the vertical axis 460 and can be fixedly secured to the front part of the trailing implement, such as a rotary mower 10, by support members 470. The swing arm 430 is telescopically adjustable, the arm comprising a sleeve slidable with respect to an inner member 450 and being lockable in a desired position by suitable securing means. Optionally, the swing arm is connected to the bracket or housing 480 by an engagement member receivable within a short vertical slot to allow a limited range of vertical movement between the swing arm and the crossbar 420. In this manner, the coupling device allows for sideways and a small degree of up and down movement of the trailing implement with respect to the tractor. In this embodiment, stabilisers with feet 490 are mounted via a bracket to the end of each leg 440. These may be fixed in a retracted position when the mower is coupled to the tractor but lowered to contact the ground thereby supporting the coupling device that remains attached to the mower when released from the tractor.

Figures 7A and 7B of the accompanying drawings illustrate an alternative embodiment of a coupling mechanism 80 according to the present invention Again, for the sake of simplicity, features that are identical to features already discussed in relation to earlier figures are provided with the same reference numerals. Figure 7A illustrates part of the coupling device attached to link arms 6 that would be attached to a tractor. Figure 7B illustrates the complete coupling device 80 attached to a rotary mower 10 and tractor 2 as hereinbefore described. In this embodiment, the crossbar is formed integrally with the legs as a substantially n-shaped member 82, the end of each leg being provided with a bracket 85 for attachment to the end of each link arm 6 of the tractor. A housing 84 is provided substantially centrally surrounding the crossbar of the member 82, the housing supporting a ball or universal joint 86 which is connected to a swing arm 83. Additionally, a supplemental link member 88 is attached to the bracket 84 for attachment to the rear of the tractor (see Figure 7B).

Swing arm 83 is telescopically attached to an inner member 85 and fixed to the front of a rotary mower by support members 87 as with coupling device 40. The coupling device again includes stabilisers with feet 89 mounted via a bracket to the end of each leg of member 82. These may be in a retracted position when the mower is coupled to the tractor but lowered to contact the ground thereby supporting the coupling device that when released from the tractor.

The coupling device 80 provides the same advantages as couplings 40, 400 in that the rotary mower 10 is semi-mounted to the tractor via link arms 6 with the pivot point 86 moved rearwardly such that it lies substantially midway along the driveline shaft 14, thereby preventing link arms 6 colliding with the driveline shaft guard and enabling standard single cardan joints 50 to be installed at the end of the driveline shaft 14, removing the need to use expensive constant velocity joints.

Thus, a coupling device according to the present invention may include a ball or universal joint to provide an alternative type of hitching and this allows for movement in all directions. However, in order to operate effectively, the front hitch would need the third mounting point known as a top link 88. This type of hitching is less favorable when unhitching, as once unattached it proves to be unstable and difficult to secure safely. Nevertheless, suitable support members may be provided to address this issue.

While the coupling mechanism is illustrated with reference to coupling of a rotary mower to a tractor, it is to be appreciated that it could be used in relation to any type of light work trailing implement that does not extend too far behind the tractor, being connected to a tractor via a single input drive shaft. Furthermore, in an alternative embodiment, the pivot point provided substantially midway along the single driveline shaft may be provided beneath the shaft rather than above it. The coupling mechanism may include other variations, such as the swing arm being of a fixed length and/or being attached to the trailing implement via a single or more than two support members.

It is to be appreciated that modifications to the aforementioned coupling device may be made without departing from the principles embodied in the examples described and illustrated herein.

Claims

CLAIMS: 1. A coupling device for connecting a trailing implement to a tractor, the coupling device comprising: at least two leg members each configured to be attachable to a link arm of a tractor; a crossbar extending between the leg members; and an arm extending rearwardly from the crossbar and being pivotably attached thereto, the arm being configured to be fixedly secured to a trailing implement.
2. The coupling device as claimed in claim 1, wherein the arm is pivotably attached to the crossbar substantially mid-way between the leg members.
3. The coupling device as claimed in claim 1 or claim 2, wherein the arm is attached to the crossbar by at least one joint, the at least one joint providing at least two directional movement, for example up and down or side to side.
4. The coupling device as claimed in claim 3, wherein the arm is attached to the crossbar by one or multiple joints to provide multi directional movement.
5. The coupling device as claimed in any one of the preceding claims, wherein a housing or bracket is provided that is connected to the arm and is attached to the crossbar about a vertical axis to allow side to side movement.
6. The coupling device as claimed in claim 5, wherein the arm is connected to a C-shaped bracket that surrounds the crossbar, the bracket being connected to the crossbar via a vertical pin extending between an upper and a lower end of the bracket.
7. The coupling device as claimed in claim 4, wherein a housing is fixedly secured to the crossbar and has a socket for a ball joint connected to the arm, whereby the ball joint provides for both sideways and up and down movement of the arm with respect to the crossbar.
8. The coupling device as claimed in any one of the preceding claims, wherein the arm is secured to the trailing implement by at least one support member, preferably two support members, extending from the arm and attachable to the front of the trailing implement.
9. The coupling device as claimed in any one of the preceding claims, wherein the arm is telescopically adjustable.
10. The coupling device as claimed in any one of the preceding claims, wherein a pair of stabilisers is provided for supporting the coupling device when it is disconnected from the link arms of a tractor.
11. The coupling device as claimed in claim 10, wherein each stabiliser comprises a longitudinal prop that is slidably mounted to a part of the coupling device, the stabiliser being securable in a raised and a lowered position.
12. The coupling device as claimed in any one of the preceding claims, wherein at least one additional link member extends from the crossbar for connection to the tractor.
13. A trailing implement, particularly but not exclusively a rotary mower, the trailing implement fitted with a coupling device according to any one of the preceding claims.
14. A tractor coupled to a trailing implement by a coupling device according to any one of claims 1 to 12, wherein the tractor has a pair of link arms extending from a rear of the tractor, the link arms being pivotably or fixedly connected to the leg members of the coupling device and a single driveline shaft extends from the tractor to the trailing implement, and wherein the pivot point of the coupling device lies substantially mid-way along the single driveline shaft.
15. The tractor coupled to a trailing implement as claimed in claim 14, wherein each end of the driveline shaft has a standard, non-constant velocity joint.
16. The tractor coupled to a trailing implement as claimed in claim 14 or claim 15, wherein the single driveline shaft extends below the coupling device.
17. A method of coupling a trailing implement to a tractor, the method comprising the steps of: providing a coupling device according to any one of claims 1 to 12; fixedly securing the arm of the device to a front of the trailing implement; pivotably or fixedly securing each leg member of the device to a respective link arm at a rear of the tractor; and attaching a joint to each end of a driveline shaft, one joint being attached to a power input of the trailing implement and the other joint being attached to a power take off shaft of the tractor, wherein the pivot point of the coupling device lies substantially mid-way between the joints.
18. The method according to claim 16, wherein a standard non-constant velocity joint is attached to each end of the driveline shaft.