GB2523120A

GB2523120A - Agricultural mower

Info

Publication number: GB2523120A
Application number: GB1402477.2A
Authority: GB
Inventors: Richard John Lovell Burman; David J Mehaffy
Original assignee: Kidd Farm Machinery Ltd
Current assignee: Kidd Farm Machinery Ltd
Priority date: 2014-02-12
Filing date: 2014-02-12
Publication date: 2015-08-19
Anticipated expiration: 2034-02-12
Also published as: GB201402477D0; GB2523120B

Abstract

An agricultural mower having a plurality of rotors, each rotor comprising one or more cutting blades arranged to rotate about a rotational axis extending substantially vertically when in use; wherein each rotor has a respective gearbox 11a, 11b, 13a, 13b, 13c arranged to drive the rotor; wherein drive shafts 14a, 14b, 14c extend between the gearboxes; and wherein the plurality of rotors are arranged in first and second rows, the first and second rows being offset from each other in a fore/aft direction of the mower. The mower may comprise a base portion 3 and a wing portion 4, 5 wherein at least one of the rotors is mounted to the base portion and at least another one of the rotors is mounted to the wing portion, wherein the wing portion is pivotable relative to the base portion

Description

Agricultural Mower

Field of the Invention

The present invention relates to an agricultural mower.

Background to the Invention

Agricultural mowers are devices used for cutting grass, field crops or other plants growing on the ground, for example to clear an area or to cut grass or other crops for use as hay or silage. A common design of mower comprises a body which is adapted to he towed behind a tractor, and a rotor comprising cutting blades which rotate about a vertical axes, or alternatively a plurality of rotors arranged in a line across the width of the body.

Mowers with a single rotor suffer from the disadvantage of a relatively narrow cutting width and high weight since the rotor is large and is therefore heavy and requires heavy support components. Mowers with a line of rotors can provide a wider cutting width hut these still tend to be heavy and the gaps between adjacent rotors leave lines of un-cut material when the mower is operated. The problem caused by gaps between adjacent rotors may be eliminated by reducing the spacing between adjacent rotors such that the cutting diameters of adjacent rotors overlap, and timing the rotors so that the blades do not collide. However, this puts a heavy load on the gearbox and increases the cost and complexity of the mower, and if one rotor fails the device is rendered inoperable.

Summary of the Invention

A first aspect of the invention provides an agricultural mower having a plurality of rotors; each rotor comprising one or more cutting blades arranged to rotate about a rotational axis extending substantially vertically when in use; wherein each rotor has a respective gearbox arranged to drive the rotor; wherein drive shafts extend between the gearboxes; and wherein the plurality of rotors are arranged in first. and second rows, the first and second rows being offset from each other in a fore/aft direction of the mower.

An agricultural mower is a device for cutting grass or other plants growing on the ground. The mower may he a simple mower or alternatively may he adapted to perform further operations in addition to cutting, for example collecting cut material or placing cut material into rows or piles.

By providing a plurabty of rotors arranged in two consecutive rows, the mower can he made more compact and lighter than a conventional mower including a single brge rotor or a small number of large rotors arranged in a single row. lii particular the mower may be shorter in its fore/aft direction and therefore more compact and lighter.

Drive shafts extending between the gearhoxes provide a robust and reliable drive mechanism to drive the respective gearhoxes associated with each rotor.

With respect to the rotor axes, extending substantially vertically means substantially vertically when the mower is on substantially level ground and the rotors are operable to rotate. It will be appreciated that the rotational axes may face in another direction when the mower is on highly uneven ground or when the mower is not in its intended orientation, for example if it is stored on its side. Further it will be appreciated that the rotational axes may not be disposed exactly vertically but may instead be inclined, br example at a small angle to the vertical, while still being substantially vertical.

The fore/aft direction is a direction substantially parallel to the direction of travel of the mower in use. As will be explained below, the mower may have a single direction of use (in which ease the fore and aft directions will always be the same), or alternatively the mower may be adapted to be used in both directions in a push or pull conbiguration (in which case the lore and alt directions may switch depending on the direction of use).

The gearhoxes ob two adjacent rotors may he coupled together by a single driveshabt which is connected directly to the respective gearboxes of the rotors, or alternatively there may be one or more additional intervening components, for example a further gearbox and/or an additional driveshaft.

Each row may comprise one or a plurality of rotors. The rotors making up each row are preferably arranged along a substantially straight line which is substantially perpendicular to the direction of travel of the mower in use. However, other arrangements are possible. for example rotors may be arranged along a curved line or in a chevron formation, or along a straight line which is offset at an angle to the direction perpendicular to the fore/aft direction. The two rows are preferably substantially parallel. Substantially parallel means that the rows may be exactly S parallel with each other or alternatively that the angle between the rows is small, for example less than 20 degrees. Alternatively the angle between the rows may he greater. for example 20 degrees or more.

Each gearbox associated with a respeclive one of the rotors has an input coupled to a driveshaft and an output which drives the rotor, the input and output being connected by gears. Some or all of the gearhoxes may provide an increased speed at the output such that thc rotor speed is greater than the input speed. For example, one or more of the gearboxes may have a gear ratio of between 1:1.5 and 1:2.5. For example. a gearbox may have a gear ratio of I: 1.93 such that a drive shaft speed of 1000rpm results in a rotor speed ol 1930rpm. The gearhoxes may he adapted to drive all ol the drive shafts at the same speed and all of the rotors at the same speed which may or may not be equal to the speed of the drive shafts. Alternatively the gearboxes may be adapted to drive different drive shafts at different speeds and/or to drive different rotors at different speeds. The mower may further comprise an intermediate gearbox which does not directly drive a rotor, but which supplies drive power to one or more gearboxes associated with specific rotors. The intermediate gearbox preferably has an input and two outputs and has a gear ratio of 1:1.

Each rotor has a cutting diameter defined by the path of the outer-most tip of the cutting blades, and the rotors may he spaced apart such that the cutting diameters of the rotors do not overlap. The rotors may be spaced apart such that the cutting blade(s) of each rotor do not overlap with the cutting blade(s) of the adjacent rotor(s) as they rotate when viewed from a vertical direction. Therefore the cutting blades of the respective rotors do not collide with each other when the rotors arc operated, and the rotors do not need to be timed to avoid collisions. For example, if each rotor has a cutting diameter ol 900mm and the iirst and second rows are spaced apart by 450mm in the fore/aft direction, each rotor may be spaced apart from the adjacent rotor(s) in the other row by approximately 800mm such that the cutting diameters do not overlap.

The offset between the first and second rows in the fore/aft direction is preferably comparatively small compared to the cutting diameters of the rotors and the spacing between adjacent rotors in a direction perpendicular to the fore/aft direction in order to minimise the length awl weight of the mower. The fore/aft offset between the first S and second rows is preferaffly between 20% and 80% of the cutting diameters of the rotors, more preferaffly between 30% and 70% of the cutting diameters, more preferably between 40% and 60% of the cutting diameters, awl most. preferably between 45% and 55% of the cutting diameters, although other offsets arc possible.

The offsct betwecn the first and second rows may be equal to approximately 50% of the cutting diameter of the rotors. For example, if each rotor has a cutting diameter of 900mm, the first and second rows may be spaced apart by approximately 450mm in the lore/aft direction.

Each rotor has a cutting width in a direction perpendic&ar to the fore/aft direction of the mower, and the rotors may he spaced apart such that the cutting widths of the rotors overlap with each other when viewed from a direction parallel to the fore/aft direction of the mower. Therefore the mower does not leave a gap between adjacent pairs of rotors in which material is not cut. Preferably each rotor cutting width overlaps with the cutting width(s) of the or each adjacent rotor such that no gaps are left across the entire cutting width of the mower.

A plurality of rotors may be connected together in series such that each rotor in the series is driven by one or more adjacent rotors via drive shafts connected between the gearboxes of the respective rotors and/or drives one or more adjacent rotors via drive shafts connected between the gearhoxes of the respective rotors.

The gearbox of a rotor at an end of a series only receives drive power from a gearbox of another rotor in that series. The ge' -box of a rotor at an intermediate position in a series transmits drive power to the gearbox(es) of one or more other rotors in that series, as well as receiving drive power either from the gearbox of another rotor in that series or from a separate drive shaft used to deliver drive power to that series.

Preferably the rotors forming the first row are connected together in a first series and the rotors forming the second row are connected together in a second series. In a preferred embodiment power is supplied to the first series by a drive shaft which is coupled directly to the gearbox of one rotor in the first series, and power is supplied to the second series by a drive shaft coupled to an intermediate gearbox which does not directly drive a rotor, but which supplies drive power to the rotors in the second series.

In other embodiments rotors from the first and second rows may be coupled together in a single series or rotors forming part of a single row may he coupled together in more than one separate series.

The mower may comprise a base portion and a wing portion. wherein at least one of the rotors is mounted to the base portion and at least another one of the rotors is mounted to the wing portion, wherein the wing portion is pivotable relative to the base portion between a deployed position and a raised, retracted position. Alternatively the mower may not include wing portions and all rotors may be mounted to a single base portion.

In one embodiment at least one rotor of the first row and at least one rotor of the second row are mounted to the base portion and at least one rotor of ihe first row and at least one rotor of the second row are mounted to the wing portion. Alternatively the base portion and/or the wing portion may include one or more rotors from a single row only. Preferably the mower includes two wing portions mounted on opposing side edges of the base portion. In the deployed position the rotational axes of the rotors mounted to the wing portions are substantially parallel to the rotational axes of the rotors mounted to the base portion. The mower may therefore have a comparatively large width when the wing portions are deployed for cutting a wide area and a reduced width when the wing portions are retracted for ease of movement and storage of the mower. The wing portions may each comprise a skid at their outer-most side ends with respect to the base portion.

A drive shaft may be coupled to a gearbox mounted to the base portion and to the gearbox of a rotor mounted to the wing portion. A rotor mounted to the wing portion may therefore he driven by the same drive mechanism as the base portion-mounted rotors. The base portion-mounted gearbox which drives the gearbox of the wing portion-mounted rotor may be a gearbox of a specific base portion-mounted rotor or alternatively may he an intermediate gearbox which does not directly drive a rotor, hut which supplies drive power to one or more gearhoxes associated with specific rotors.

Where multiple rotors are mounted to the wing portion. a second drive shaft may be coupled to a further gearbox mounted to the base portion and to the gearbox of a second rotor mounted to the wing portion. Where the base portion and wing portion both comprise rotors from the first and second rows, preferably a wing portion-mounted rotor of the first row is driven by the gearbox of a base portion-mounted rotor of the first row, and a wing portion-mounted rotor of the second row is driven by the gearbox of a base portion-mounted rotor of the second row.

Where the mower includes two wing portions an equivalent rotor and drive arrangement is preferably mirrored on the second wing portion.

The drive shaft connected between the base portion-mounted gearbox and the gearbox of the wing portion-mounted rotor may he a telescoping drive shaft. The telescoping dnve shaft can extend and contract to account for relative movement of the gearboxes as the wing is pivoted relative to the base portion. The telescoping drive shaft preferably comprises a plurality of telescoping drive shaft elements and includes at IS least one universal joint to accommodate relative movement between the gearhoxes.

The gearbox of the wing portion-mounted rotor which is coupled to a base portion-mounted gearbox by a drive shaft may be further coupled to the gearbox of another wing portion-mounted rotor by a further driveshaft coupled between the respective gearhoxes. Any number of lurther rotors located on a wing portion may he connected in series and powered by the same power source as the base portion-mounted rotors.

Each rotor may comprise at least two cutting blades. For example each rotor may comprise 2,3 or 4 cutting blades. In addition, each rotor may comprise at least two mulching elements. The cutting blades (and mulching elements if present) of each rotor are preferably mounted to a rotating central huh.

The cutting blade(s) of each rotor may have a cutting diameter in the range 600mm to 1800mm, preferably within the range 700mm to 1200mm, more preferably within the range 800mm to 1000mm. and most preferably a cutting diameter of approximately 900mm. A cutting diameter of at least 600mm ensures that the number of rotors and associated gearboxes and drive shafts is not too large compared to the effective span of the mower. A cutting diameter of less than 1800mm ensures that the loads placed on the drive shafts does not become excessive, necessitating larger and heavier drive shafts, gearhoxes, and supporting components.

The mower may further comprise mounting means for mounting the mower to a vehicle used to move the mower in use, the mounting means acting to substantially prevent rotation of the mower relative to a vehicle to which the mower is mounted about an axis extending substantially vertically. The mower may therefore he mounted to the front or rear of a vehicle used to move the mower in use, for example a tractor, and may be pulled or pushed by the vehicle. This is in contrast to a traditional trailed mower which pivots or articulates relative to the driving tractor and so cannot normally be pushed due to jackknifing. Alternatively the mower may he trailed instead of mounted.

The mounting means may comprise a three point hitch. A three point hitch is a an attachment. mechanism including three separate attachment points in a triangle formation which substantially prevents relative movement between the vehicle (ie the tractor) and the mower, and which supports at least a portion of the weight of the mower. Preferably the three point hiich allows the mower to be pivoted upwardly about a horitonta axis perpendicular to the fore/aft axis of the mower while the mower is still connected to the vehicle. The three point hitch may be adapted to hold the mower in a raised configuration away from the ground.

The mower may further comprise one or more wheels adapted to run over the ground as the mower is moved in use. The wheels are preferably mounted on pivoting casters to aid with tuming and steering. Preferably the wheds are located on an opposite side of the mower to the mounting means in the fore/aft direction. Preferably the weight of the mower is supported entirely or primarily by the three point hitch in use and the wheels have a minimal (or zero) load bearing function. Alternatively the wheels may contact the ground continuous'y and have a significant load bearing function.

Alternatively wheels may not he necessary where the entire weight of the mower is supported by the three point hitch and/or skids attached to the base portion and/or wing portions of the mower.

The mower may be adapted to be coupled to a power take-off shaft extending from a vehicle used to move the mower in use so that each of the rotors is powered by the power take-off shaft. As discussed above, the rotors do not each need to receive power directly from the power take-off shaft hut may instead receive power from the power take-off shaft via one or more gearboxes, for example gearboxes of other rotors and/or intermediate gearboxes. and via one or more intermediate drive shafts. The drive shaft connecting the vehide to the mower is preferably an extendible drive shaft, allowing for pivoting of the mower about a horizontal axis of the three point hitch.

A second aspect of the invention provides apparatus for mowing an area of ground comprising a tractor and an agricultural mower according to the first aspect of the invention detachably mounted to the tractor.

Brief description of the drawings

Embodiments of the invention will now he discussed with reference to the following drawings in which: Figure 1 shows an agricultural mower in accordance with the invention mounted to a tractor; Figure 2 shows the mower of figure 1 in a retracted position; Figures 3 and 4 show top and bottom views of the mower of figure 1; Figure 5 shoes a rotor and gearbox assembly; Figure 6 shows a rotor with blades attached to a hub; Figure 7 shows an agricultural mower in an alternative embodiment. mounted to a tractor; and FigureS shows the mower of figure 7 in a retracted position.

Detailed Description of Embodiment(s)

Figure 1 shows an agricultural mower 1 mounted to a tractor 2. The mower is used to cut grass or other plants growing on the ground. The mower 1 comprises a base portion 3 and two wing portions 4, 5 pivotally mounted on opposite sides of the base portion on hinges. The wing portions 4, 5 can he held in a deployed position as shown in figure 1 by actuators 6 (shown in figure 4) when the mower is in use. When the mower is not in use, the wing portions 4, 5 can be pivoted upwardly and held in a retracted position as shown in figure 2 by the actuators, thereby reducing the width of the mower for transport or storage. The width of the base is preferably approximately the same as the width of the tractor.

The mower has a plurahty of rotors ba, lob, 12a, 12h, l2c projecting downwardly from the base portion and the wing portions, as shown in figure 3. Each rotor comprises a plurality of cutting blades 7 and a plurality of mulching blades 8 mounted to a central hub 9 which rotates about a vertical axis in use. The rotor l2a is shown in figure 5 and the cutting liadcs, mulching blades and hub arc shown in figure 6.

The rotors are arranged in two rows with the rotors l0a. lOb, forming a first row A and the rotors 12a, 12h. 12c forming a second row B, the first and second rows being offset from each other in the fore/aft direction of the mower, as shown in figure 3.

The first row is the front row when the mower is attached to the rear of a tractor as shown in figure 1 but the second row may equally be the front row when the mower is mounted to the front of a tractor as will he explained in detail below.

Whcn the mower is in usc. thc rotors lOa, lOb, 12a, 12b. 12c arc driven by a network of drive shafts and gearboxes which will be discussed in detail below so that each rotor rotates and cuts material growing from the ground. As can he seen from figure 3. the rotors are spaced apart such that their cutting diameters do not overlap.

Therefore the cutting rotors cannot collide with each other in usc and the rotors do not need to be timed. However, the cutting widths of the rotors (perpendicular to the lore/all direction) do overlap so that no gaps of un-cut material are belt between the rotors as the mower is moved forward in use.

Each rotor is provided with a respective gearbox bla, bIb, b3a, b3h, 13c arranged to drive the rotor, as can be seen in figures 1 and 4. The front row includes an intermediate gearbox 15 located between the rotors ba and lob. The intermediate gearbox 15 is driven by a primary drive shaft 16 coupled to a power take-off shaft (or PTO) of the tractor. The intermediate gearbox acts as a splitter gearbox with one input and three outputs, and drives three drive shafts l4a. 14b, l4c coupled respectively to inputs of gearboxes 1 la. 1 lb and 13a which respectively drive rotors bOa, lOb. 12a. In the first row, gearbox lla drives rotor lOa. and gearbox llb drives rotor lOb. In the second row, gearbox 13a, in addition to driving rotor 12a. comprises two outputs which drive a pair of drive shafts 1 4f, I 4g which are respectively coupled to gearboxes 13b, 13c which drive wing portion-mounted rotors 12b, 12c. In this way the gearboxes 13a, 13b, 13c of the second row are connected in series with each other, and in parallel with the gearhoxes of the first row. The drive shafts 14f, 14g are telescoping drive shafts and include universal joints at each end to account for relative movement between the gearboxes when the wing portions 4. 5 are pivoted upwardly with respect to the base portion 3. Therefore the wing portions may he raised without disconnecting the driveshafts.

The intermediate gearbox 14 is a 1:1 gearbox which simply splits the drive power received between three outputs at the same speed to power the gearboxes 1 la. 1 lb. 13a. Gearboxes lla and lib each have a gear ratio of 1:1.93. Therefore when the primary driveshaft 16 rotates at 1000rpm, the gearboxes 11 a and 1 lb drive the rotors I Oa and I Oh at 1930rpm. Gearbox I 3a has a gear ratio ol 1:1.84, and therefore drives the rotor 12a as well as gearboxes 13b and l3c at 1840rpm. Gearboxes l3b and l3c each have a gear ratio of 1:1 and therefore drive the rotors 12b and 12c at 1840rpm.

In other embodiments the gear ratios may he different, for example such that each rotor is driven at the same speed.

The mower 1 is attached to the tractor via a three-point hitch mounting system 20 including three attachment points 21, 22, 23. The three-point hitch prevents articulation of the mower relative to the tractor about a vertical axis so the mower can he readily pushed as well as puflcd without jackknifing. The mower may therefore be attached to the front or hack of a tractor (or other vehicle) and operated in either direction. The three-point hitch 20 allows the mower 1 to be pivoted upwardly about the two lower attachment points 21. 22 while the mower is still attached to the tractor 2. This may be done either by detaching the arm 24 connecting the tractor to the upper attachment point 23 or by shortening the telescoping arm 24. The primary drvc shaft 16 is a telescoping drive shaft and comprises a universal joint at each end to account br rdative movement between the tractor 2 and the mower I when the mower is pivoted upwardly on its three point hitch 20.

The mower 1 further comprises wheels 30 mounted on pivoting casters extending from the rear edge of the base portion 3. Optionally wheels may also be mounted to the rear edges of the wing portions 4, 5 (as shown in figures 7 and 8 in relation to another embodiment of the invention). The wheels 30 are not adapted to carry a significant portion of the weight of the mower, which is instead supported by the three-point hitch 20 in normal use on fiat ground. The wing portions 4, 5 further include skids 31 at their outboard edges which again (10 not carry a significant portion of the weight of the mower in normal use on flat ground. The whcels and/or skids may bc omitted in other embodiments.

The mower may additionally comprise guards which cover and protect the drive shafts and/or gearboxes, although these have been omitted from the drawings for improved clarity.

In another embodiment the front row may additionally comprise wing-mounted rotors lOc and lOd driven respectively by gearboxes 1 ic, lid such that both the first and second rows extend onto the wing portions, as shown schematically from above and below in figures 7 and 8. In this second embodiment the same reference numerals as previously used are retained for identical or equivalent components. and the drive shafts are not shown for increased clarity. In this embodiment gearbox 1 la, in addition to driving rotor lOa. comprises an output which drives a drive shaft coupled to gearbox 1 ic which drives the wing portion-mounted rotor lOc. Similarly, gearbox lib. in addition to driving rotor lob, comprises an output which drives a drive shaft coupled to gearbox I Id which drives the wing portion-mounted rotor lOd. In this way the gearhoxes I Ia, I Ib, I Ic, lid of the first row are connected in series with each other, and in parallel with the gearboxes of the first row. The additional drive shafts extending between the base portion and the wing portions to the gearboxes lie, 1 ld are telescoping drive shafts and include universal joints at each end to account for relative movement between the gearboxes when the wing portions 4, 5 are pivoted upwardly with respect to the base portion 3. In this second embodiment the wing portions are also provided with wheels 30.

The skilled person wifl appreciate that the above-described embodiments are for illustrative purposes only, and that other embodiments falling within the scope of the invention are envisaged. Several non-limiting examples of alternative embodiments

are discussed in the summary section.

Claims

Claims 1. An agricultural mower having a plurality of rotors; each rotor comprising one or more cutting blades arranged to rotate about a rotational axis extending substantially vertically when in use: wherein each rotor has a respective gearbox arrangcd to drive thc rotor; whercin drivc shafts extend between the gearboxes; and wherein the p'urality of rotors are arranged in first and second rows, the first and second rows being offset from each other in a lore/alt direction ol the mower.
2. An agricultural mower according to claim 1. wherein each rotor has a cutting diameter defined by the path of the outer-most tip of the cutting blades, wherein the rotors are spaced apart such that the cutting diameters of the rotors do not overlap.
3. An agricultural mower according to claim 1 or 2, wherein each rotor has a cutting width in a direction perpendicular to the fore/aft direction of the mower, wherein the rotors are spaced apart such that the cutting widths of the rotors overlap with each other when viewed from a direction parallel to the fore/aft direction of the agricultural mower.
4. An agricultural mower according to any preceding claim, wherein a plurality of rotors are connected together in series such that each rotor in the series is driven by one or more adjacent rotors via drive shafts connected between the gearboxes of the respective rotors and/or drives one or more adjacent rotors via drive shafts connected between the gearboxes of the respective rotors.
5. An agricultural mower according to any preceding claim, comprising a base portion and a wing portion. wherein at least one of the rotors is mounted to the base portion and at least another one of the rotors is mounted to the wing portion, wherein the wing portion is pivotable relative to the base portion between a deployed position and a raised, retracted position.
6. An agricultural mower according to claim 5. wherein a drive shaft is coupled to a gearbox mounted to the base portion and to the gearbox of a rotor mounted to the wing portion.
7. An agricultural mower according to claim 6, whcrein thc drive shaft connccted between the base portion-mounted gearbox and the gearbox of the wing portion-mounted rotor is a telescoping drive shaft.
8. An agricultural mower according to claim 7, wherein the gem' *box of the wing portion-mounted rotor which is coupled to a base portion-mounted gearbox by a drive shaft is lurther coupled to (he gearbox of another wing portion-mounted rotor by a further driveshaft coupled between the respective gearboxes.
9. An agricultural mower according to any preceding claim, wherein each rotor comprises at least two cutting blades.
10. An agricultural mower according to any preceding claim, wherein the cutting blade(s) of each rotor have a cutting diameter in the range 600mm to 1800mm.preferably within the range 700mm to 1200mm, more preferably within the range 800mm to 1000mm. and most preferably a cutting diameter of approximately 900mm.
11. An agricultural mower according to any preceding claim, further comprising mounting means for mounting the mower to a vehicle used to move the mower in use, the mounting means acting to substantially prevent rotation of the mower relative to a vehicle to which the mower is mounted about an axis extending substantially vertically.
12. An agricultural mower according to claim 11. wherein the mounting means comprises a three point hitch.
13. An agricultural mower according to daim 11 or 12, further comprising one or more wheels adapted to run over the ground as the mower is moved in use.
14. An agricultural mower according to any preceding claim, wherein the agricultural mower is adapted to be coupled to a power take-off shaft extending from a vehicle used to move the mower in use so that each of the rotors is powered by the power take-off shaft.
15. Apparatus for mowing an ama of ground comprising a tractor and an agricultural mower according to any preceding claim detachably mounted to the tractor.