Grass treatment device and system

Abstract

A grass treatment device comprises a traction frame 10 with a driven rear roller or wheel and a tool frame 30 with a grass treatment tool and a front roller or wheel. The grass treatment tool can be a

Description

TECHNICAL FIELD The present invention relates to grass treatment devices, e.g. mowers. The invention is particularly related to fixed head grass treatment devices, e.g. fixed head reel mowers. BACKGROUND Grass treatment devices are used for treating grass surfaces such as lawns, playing fields, parkland and golf courses. Types of grass treatment device may include mowers, cleaners and scarifiers. Reel mowers are known for cleanly and precisely cutting grass at low heights. Reel mowers typically comprise a cutting unit having a cutting reel and a bedknife. The cutting reel comprises a set of blades which spin and cut the blades of grass against the bedknife as the reel mower is moved along the grass surface. The inclination angle of the bedknife with respect to the ground (also referred to as the “attitude angle”) and the distance between the centre of the cutting reel and the front edge of the bedknife in the front-rear direction (also referred to as the “behind centre distance”) are factors that affect the quality of cut for a desired height of cut. Reel mowers can be categorised into two types - fixed head mowers and floating head mowers. In fixed head mowers, the cutting unit is rigidly mounted to a frame which carries a rear traction roller positioned behind the cutting unit and a front roller positioned in front of the cutting unit. The rear traction roller and the front roller engage the ground during use and the rear traction roller can be driven by e.g. an internal combustion engine or a battery and electric motor to propel the mower along the ground. In some fixed head mowers, the front roller is provided with a height adjustment mechanism to allow the user to adjust the height of cut. However, adjustment of the front roller will also result in a change to the bedknife attitude angle and the behind centre distance, which can result in these variables falling outside the optimal range for the desired height of cut. Therefore, only small adjustments can be made without compromising the quality of cut. In floating head mowers, the mower comprises a mower frame which carries a rear traction roller, similar to a fixed head mower. However, the cutting unit in a floating head mower is mounted to the mower frame in a suspended (i.e. non-rigid) manner that allows the cutting unit to move relative to the mower frame so that the cutting unit can follow the contours of the ground independently of the mower frame. In floating head mowers, the cutting unit will also typically comprise a rear (non-driven) roller in addition to a front roller for supporting the cutting unit on the ground. In some floating head mowers, both the front roller and the rear roller of the cutting unit are provided with independent height adjustment mechanisms, which gives the user greater freedom to select an optimal bedknife attitude and behind centre distance for a desired height of cut. Although floating head mowers generally allow the mower to maintain a consistent cutting height over bumpy ground and can provide greater adjustment of the position of the cutting unit, floating head mowers are typically more expensive, less balanced (as they are more front heavy) and more difficult to maintain due to the presence of more moving parts compared to fixed head mowers. For generally flat surfaces, fixed head mowers can offer a cheaper, simpler and more reliable option. However, as discussed above, fixed head mowers only offer a narrow range of optimal positioning of the cutting unit, which means that the mower cannot be used for a wide range of heights of cut without compromising quality of cut. SUMMARY OF THE INVENTION In a first aspect, the present invention provides a grass treatment device system comprising a grass treatment device. The grass treatment device comprises a traction frame carrying a rear ground engaging member and a drive system configured to drive rotation of the rear ground engaging member. The grass treatment device further comprises a tool frame carrying a grass treatment tool and a front ground engaging member. The system further comprises a plurality of exchangeable connection members, each connection member being configured to rigidly couple the tool frame to the traction frame in a different position relative to the traction frame, wherein the vertical position and / or angular position of the tool frame relative to the traction frame is different in each position. Each connection member may be removably attachable to the tool frame and to the traction frame. Each connection member may comprise a plurality of engagement features, each engagement feature being configured to engage a corresponding feature on the tool frame or the traction frame, wherein when the engagement features are engaged with their corresponding features on the tool frame or the traction frame, the tool frame is set in a particular position relative to the traction frame. The overall spatial arrangement of the engagement features may be different for each connection member. The plurality of engagement features may comprise a first group of engagement features configured to engage with corresponding features of the tool frame and a second group of engagement features configured to engage with corresponding features of the traction frame, wherein the position of the first group of engagement features relative to the second group of engagement features is different for each connection member. The spatial arrangement of the engagement features within the first group may be the same for each connection member and the spatial arrangement of the engagement features within the second group may be the same for each connection member. The plurality of engagement features may comprise at least one aperture or recess configured to engage a corresponding protruding feature on the tool frame or the traction frame. The plurality of engagement features may comprise at least one recess extending inwardly from the outer perimeter of the connection member, and the at least one recess may be configured to engage a corresponding protruding feature on the tool frame or the traction frame in a direction perpendicular to the longitudinal axis of the protruding feature. The connection member may further comprise a plurality of fastening features arranged relative to the engagement features such that when the plurality of engagement features are engaged with their corresponding features on the tool frame and the traction frame, each fastening feature is aligned with a corresponding feature on the tool frame or the traction frame to receive a fastener to attach the connection memberto the tool frame or the traction frame. The plurality of fastening features comprises at least one aperture or recess configured to align with a corresponding aperture or recess in the tool frame or the traction frame. The plurality of connection members may comprise a plurality of pairs of connection members arranged on opposing lateral sides of the grass treatment device. The tool frame may further comprise a height adjustment mechanism configured to allow the vertical position of the front ground engaging member to be adjusted relative to the tool frame. The grass treatment device may be a mower and the grass treatment tool may comprise a cutting reel and a bedknife for cutting grass. The mower may be a reel mower. The mower may be a fixed head mower. The grass treatment device may be a fixed head grass treatment device. In another aspect, the present invention provides a grass treatment device comprising a traction frame carrying a rear ground engaging member and a drive system configured to drive rotation of the rear ground engaging member. The device further comprises a tool frame carrying a grass treatment tool and a front ground engaging member. The device further a coupling structure configured to rigidly couple the tool frame in a set position relative to the traction frame. The coupling structure is further configured to allow the position of the tool frame to be changed and set in a different position having a different vertical position and / or angular position relative to the traction frame. The coupling structure may comprise a connection member configured to set the tool frame at a particular vertical position and angular position relative to the traction frame. The connection member may be removably attached to the tool frame and the traction frame to allow the connection member to be exchanged with a different connection member to change the position of the tool frame relative to the traction frame. The connection member may comprise any of the feature mentioned in relation to the first aspect of the invention described above. The coupling structure may comprise a guideway that defines a path along which the tool frame can move relative to the traction frame. The guideway may be configured such that movement of the tool frame along the path changes the vertical position and / or angular position of the tool frame relative to the traction frame. The guideway may define a linear or curved (e.g. arcuate) path. The coupling structure may comprise a fastener retained in the guideway. Tightening the fastener may set the position of the tool frame relative to the traction frame. Loosening the fastener may allow the tool frame to move along the path to change its position relative to the traction frame. The tool frame and the traction frame may comprise a plurality of interlocking teeth. The coupling structure may be configured to allow the interlocking teeth to disengage when the coupling structure is loosened (e.g. when the above-mentioned fastener is loosened) to allow the position of the tool frame to be changed relative to the traction frame. The grass treatment device may further comprise a linear actuator configured to move the tool frame along the path defined by the guideway, and a control system comprising a controller configured to control the linear actuator to move the tool frame a particular distance along the path. The path may linear or curved (e.g. arcuate). The tool frame may further comprise a height adjustment mechanism configured to allow the vertical position of the front ground engaging member to be adjusted relative to the tool frame. The grass treatment device may be a mower and the grass treatment tool may comprise a cutting reel and a bedknife for cutting grass. The mower may be a fixed head mower. The mower may be a reel mower. The grass treatment device may be a fixed head grass treatment device. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of a mower. Figure 2 is a side view of the mower. Figure 3 is a perspective view of the traction unit of the mower. Figure 4 is a perspective view of the cutting unit of the mower. Figure 5 is an exploded view of the mower, showing the traction unit, cutting unit, and a pair of connection members. Figure 6 is an exploded view showing the engagement and fastening features of the connection member and the corresponding features of the tool frame and the traction frame. Figure 7 is a plan view of a first example connection member. Figure 8 is a plan view of a second example connection member. Figure 9 is a side view of the mower with the first example connection member attached. Figure 10 is a side view of the mower with the second example connection member attached. Figure 11 is a partial perspective view of an alternative connection member coupled to the tool unit and the traction unit. Figure 12 is an exploded view of Figure 11. DETAILED DESCRIPTION Figures 1 and 2 show a grass treatment device in the form of a mower 1 for cutting grass. The mower 1 comprises a traction unit 10 at the rear end of the mower 1 and a cutting unit 30 at the front end of the mower 1. Figure 3 shows the traction unit 10 in isolation. The traction unit 10 comprises a rear ground engaging member that rotates about a horizontal axis transverse to the forward direction to propel the mower 1 along the ground in use. In this example, the rear ground engaging member is a rear traction roller 12 which extends transversely across the traction unit 10 but could also take the form of other rolling elements such as one or more wheels. The traction unit 10 further comprises a drive system 14 configured to rotationallydrive the traction roller 12 to propel the mower 1 along the ground. The drive system 14 may be any suitable drive system for driving rotation of the traction drum and may include an internal combustion engine or an electric motor powered by a battery pack, for example. The traction unit 10 further comprises a traction frame 18 that carries the traction roller 12 and the drive system 14. The illustrated traction frame 18 comprises two laterally spaced side plates 20 between which the traction roller 12 is mounted for rotational movement about its longitudinal axis. A handle 16 may be mounted to the traction frame 18 which the user may grip in use to guide the direction of the mower 1 or manually push the mower 1. The handle 16 may comprise one or more controls configured to provide inputs to a control system of the drive system. For example, the handle 16 may comprise a control for starting and stopping propulsion of the mower 1 and may comprise a control for controlling the speed of the mower 1. Figure 4 shows the cutting unit 30 in isolation. The cutting unit 30 comprises a cutting reel 36 and a bedknife 40 (visible in Figure 2) which are arranged for cutting grass in a manner well known in the art. The cutting reel 36 comprises a plurality of circumferentially spaced, helical blades and is arranged to rotate about a transverse horizontal axis. The bedknife 40 is stationary relative to the cutting reel 35 and is positioned near the bottom of the cutting reel 36 so that the front edge of the bedknife 40 lightly contacts the blades of the cutting reel 36. As the cutting reel 36 rotates, the blades of the cutting reel sweep blades of grass against the stationary bedknife to cut them using a shearing action. The cutting unit 30 further comprises a tool frame 42 which carries the cutting reel 36 and the bedknife 40. The tool frame 42 comprises two laterally spaced side plates 44 between which the reel cutter 36 is mounted for rotation. The cutting unit 30 further comprises a front ground engaging member in the form of a front roller 32. The front roller 32 supports the mower 1 in conjunction with the rear traction roller 12 for rolling movement along the ground. The front roller 32 extends transversely across the cutting unit and is mounted on the tool frame 42 for rotation about a transverse horizontal axis. The front roller 32 is arranged in front of the cutting reel 36 so that the cutting reel 36 is located between the front roller 32 and the rear traction roller 12 when the cutting unit 30 is coupled to the traction unit 10. The cutting unit 30 may further comprise a height adjustment mechanism 34 configured to allow the vertical position of the front roller 32 to be adjusted relative to the tool frame 42. The height adjustment mechanism 34 may take any suitable form for allowing the front roller 32 to be moved up and down relative to the tool frame 42. For example, the height adjustment mechanism 34 may comprise threaded shafts that are coupled to either end of the front roller 32 and are received in threaded structures mounted to the tool frame 42 such that rotation of the threaded shafts results in upward or downward movement of the front roller 32 relative to the tool frame 42. An example height adjustment mechanism that may be used with the invention is disclosed in PCT publication no. WO 2007 / 003871 A1, which is hereby incorporated by reference in its entirety. The tool frame 42 is rigidly coupled to the traction frame 18 via a coupling structure in the form of a pair of laterally spaced connection members 50 arranged on either side of the mower 1, which can be seen in Figures 1 and 2, and in the exploded view of Figure 5. Each connection member 50 is removably attached to both the tool frame 42 and the traction frame 18. Each connection member 50 is removably attached at a front end of the traction frame 18 and a rear end of the traction frame 42. In the illustrated example, each connection member 50 is removably attached to a side plate 44 of the tool frame 42 and a side plate 20 of the traction frame 18. The connection members 50 can be attached to the tool frame 42 and the traction frame 18 using any suitable fasteners that can readily be undone, e.g. threaded fasteners, such as screws or bolts. Once the connection members 50 are attached to the tool frame 42 and the traction frame 18, the cutting unit 30 is retained in a fixed position relative to the traction frame 18 and cannot move or rotate relative to the traction frame 18. In this example, each connection member 50 is in the form of a plate orientated in a generally vertical plane, but other forms and shapes and orientations could be used depending on the configuration of the tool frame 42 and the traction frame 18. Furthermore, although the connection members 50 have been provided as a pair of laterally spaced connection members 50 for stability, the mower 1 could comprise only one connection member 50 or more than two connection members 50 arranged at any suitable locations on the tool frame 42 and the traction frame 18 to rigidly couple the cutting unit 30 to the traction unit 10. The connection member 50 comprises a plurality of engagement features configured to align with and engage corresponding features on the tool frame 42 and the traction frame 18. The engagement features may comprise a plurality of apertures or recesses, each configured to engage (receive) a corresponding protruding feature on the tool frame 42 or the traction frame 18. In this illustrated example, most clearly shown in the exploded view of Figure 6, the engagement features of the connection member 50 comprise apertures 52a, 52b, 52c which are dimensioned to receive the heads of bolts 46a, 46b, 46c that protrude horizontally in a transverse direction from the side of the tool frame 42. The diameter of the apertures 52a, 52b, 52c is slightly larger than the diameter of the heads of bolts 46a, 46b, 46c so that at least a portion of the bolt heads are received inside the apertures. The protruding features of the tool frame 42 do not need to be bolt heads and could be any suitable protrudingfeature that can be received in the apertures 52a, 52b, 52c of the connection member 50. The engagement features of the connection member 50 further comprise recesses 54a, 54b in the form of notches which extend inwardly from the outer perimeter of the connection member 50. The recesses 54a, 54b are dimensioned to receive the shafts of bolts 22a, 22b that protrude horizontally in a transverse direction from the side of the traction frame 18. The protruding features of the traction frame 18 do not need to be in the form of bolt shafts and could instead be any suitable protruding feature that can be received in the recesses 54a, 54b. Given that the recesses 54a, 54b extend inwardly from the outer perimeter of the connection member 50, each shaft of the bolts 22a, 22b can be received in a corresponding recess 54a, 54b via the opening in the outer perimeter of the connection member 50, i.e. in a direction perpendicular to the longitudinal axis of the protruding bolts 22a, 22b. This is in contrast to the apertures 52a, 52b, 52c of the connection member 50, which can only receive the heads of bolts 46a, 46b, 46c, in a direction paralleltothe longitudinal axis ofthe bolt heads. The provision of the recesses 54a, 54b allows for a convenient method of coupling the tool frame 42 to the traction frame 18, which will be explained later. The engagement features are spatially arranged on the connection member 50 such that when the engagement features are brought into engagement with their corresponding features on the tool frame 42 and the traction frame 18, the tool frame 42 is brought into a particular position with respect to the traction frame 18 that is associated with that connection member 50. The connection member 50 further comprises a plurality of fastening features, each configured to align with a corresponding feature of the tool frame 42 or the traction frame 18 to allow the connection member 50 to be removably attached to the tool frame 42 or the traction frame 18 via a fastener. In the illustrated example, the fastening features are provided in the form of apertures 56a, 56b configured to align with corresponding apertures 48, 24 in the tool frame 42 and the traction frame 18 respectively. The fastening features do not need to be in the form of apertures and other forms are possible, e.g. recesses extending inwardly from an outer perimeter of the connection member 50. The engagement features and the fastening features are configured (spatially arranged) such that when the engagement features of the connection member 50 are engaged with their corresponding features on the tool frame 42 and the traction frame 18, the fastening features are aligned with their corresponding features on tool frame 42 and the traction frame 18. In the current example, when apertures 52a, 52b, 52c, of the connection member 50 are engaged with the heads of bolts 46a, 46b, 46c of the tool frame 42 (i.e. when the heads of bolts 46a-46c have been received in the apertures 52a-52c respectively), aperture 56a of the connection member 50 is aligned with aperture 48 in the tool frame 42 to allow a fastener 58a to be received though the connection member 50 and the tool frame 42 to attach them together. Similarly, when recesses 54a, 54b are engaged with the shafts of bolts 22a, 22b of the traction frame 18 (i.e. when the shafts of bolts 22a, 22b have been received in recesses 56a, 56b), aperture 56b of the connection member 50 is aligned with aperture 24 of the traction frame 18 to allow a fastener 58b to be received though the connection member 50 and the traction frame 18 to attach them together. The invention is not limited to having one fastening feature that aligns with a corresponding feature on the tool frame 42 and one fastening feature that aligns with a corresponding feature on the traction frame 18. The connection member 50 can comprises more than one fastening feature for aligning with corresponding features on the tool frame 42 and / or more than one fastening feature for aligning with corresponding features on the traction frame 18. In this case, more than one fastener can be used to attach the connection member 50 to the tool frame 42 and / or more than one fastener can be used to attach the connection member 50 to the traction frame 18. The engagement features can thus serve the dual function of conveniently bringing the tool frame 42 into a particular position relative to the traction frame 18 and conveniently bringing the fastening features into alignment with corresponding features on the tool frame 42 and the traction frame 18. However, the engagement features are not required to perform both functions (i.e. each of these functions is optional). Once the pair of connection members 50 has been attached to both the tool frame 42 and the traction frame 18, the tool frame 42 is rigidly coupled to the traction frame 18 and cannot move or rotate relative to the traction frame 18. Although the connection member 50 shown in the illustrated example has three engagement features 52a-52c for engaging three corresponding features 46a-46c of the tool frame 42, and two engagement features 54a, 54b for engaging two corresponding features 22a, 22b of the traction frame 18, the number of engagement features is not limited to these particular amounts. In some examples, no engagement features are provided. In other examples, only one engagement feature is provided for engaging with either the tool frame 42 or the traction frame 18. In other examples, only one engagement feature is provided for engaging with the tool frame 42 and only one engagement feature is provided for engaging with the traction frame 18. In these examples, the engagement features and corresponding features on the tool frame 42 and traction frame 18 may be non-circular / non-cylindrical such that when the engagement features are engaged, the connection member 50 cannot rotate relative to the tool frame 42 or the traction frame 18, to more easily bring the fastening features into alignment. In other examples, at least two engagement features are provided for engaging the tool fra me 42 and / or the traction frame 18. In these examples, the provision of at least two engagement features helps prevent rotation of the connection member 50 relative to the tool frame 42 or the traction frame 18 when the engagement features and their corresponding features are circular / cylindrical, which helps to bring the fastening features into alignment. A greater number of engagement features also helps to spread the load acting on the connection plates 50 more evenly when the connection plates 50 are attached to the tool frame 42 and the traction frame 18. In some examples, an engagement feature could also function as a fastening feature. In the example shown in Figure 6, when a recess 56a, 56b has received a shaft of a bolt 22a, 22b, the head of one or both of the bolts 22a, 22b can optionally be tightened against the connection member 50 to thereby attach the connection member to the traction frame 18. Instead of the engagement features of the connection member 50 being in the form of apertures or recesses for engaging protruding features of the tool frame 42 and the traction frame 18, the engagement features of the connection member 50 could be in the form of protrusions configured to be receive in corresponding apertures or recesses in the tool frame 42 and the traction frame 18. As mentioned above, the provision of engagement features in the form of recesses 54a, 54b that can receive the shafts of bolts 22a, 22b in a direction perpendicular to the longitudinal axis of the transversely extending bolts 22a, 22b allows the cutting unit 30 to be mounted to the traction unit 10 using the following convenient method. First, the traction unit 18 is preferably moved into a tilted back position in which the handle 16 is resting against the ground for stability. The pair of connection members 50 is then attached to the tool frame 42 by aligning the apertures 52a, 52b, 52c with the heads of protruding bolts 46a, 46b, 46c and receivinga fastenerthrough the now-aligned apertures 56a and 48 of the connection members 50 and the tool frame 42. The cutting unit 30, with the connection members 50 attached, is then placed in front of the traction unit (if not already located there) and “hooked” onto the traction frame 18 by lifting up the rear end of the tool frame 42 and placing the connection members 50 over the shafts of the transversely extending bolts 22a on either side of the traction frame 18 such that the bolt shafts are received into the recesses 54a of the connection members 50. The rear end of the cutting unit 30 can then be released, as the weight of the cutting unit 30 is now being supported by the shafts of the bolts 22a on the traction frame 18 and the front roller 32. The front end of the cutting unit 30 is then lifted and rotated upwards about a transverse axis extending through the longitudinal axis of the shafts of the bolts 22a until the recesses 54b of the connection members 50 receive the shafts of transversely extending bolts 22b on either side of the traction frame 18. Because the recesses 54a, 54b of the connection plates 50 are now engaged with the shafts of bolts 22a, 22b of the traction frame 18, the apertures 56b of the connection plates 50 are now aligned with corresponding apertures 24 on either side of the traction frame 18. The connection members 50 can then be attached to the traction frame 18 by receiving a fastener through the now-aligned apertures 56b, 24. The tool frame 42 is now rigidly coupled to the traction frame 18 via the connection plates 50 that are attached between the tool frame 42 and the traction frame 18. The configuration of the engagement features of the connection members 50 therefore allows for a convenient, fast and efficient method for coupling the cutting unit 30 to the traction unit 10 in which the connection members 50 are attached to the cutting unit 30 first, and are then used to bring the cutting unit 30 into alignment with the traction unit 10 so that the connection members 50 can be attached to the traction unit 10 cutting unit 30. In particular, the person performing the coupling does not need to try and support the full weight of the cutting unit 30 and / or the traction unit 10 (which are generally heavy machines) while trying to hold the cutting unit 30 and the traction unit 10 in alignment so that the connection members 50 can be attached to them. Although this coupling method has been described in relation to a pair of connection members 50, this method is not limited to examples having a pair of connection members 50 and instead could be used with a single connection member 50 (e.g. located centrally in the transverse direction) or more than two connection members 50. Although the above-described configuration of the connection member 50 of the illustrated example allows for the above-described coupling method to be performed, the invention is not limited to a connection member 50 which is configured to allow the above-described coupling method to be performed. Instead of providing engagement features in the form of apertures for engaging features of the tool frame 42 and engagement features in the form of recesses for engaging features of the traction frame, these features could be swapped around so that recesses in the connection member 50 are provided for engaging bolt shafts on tool frame 42 and apertures are provided for engaging bolt heads on the traction frame 18. In this case, the method can be changed to attach the connection member 50 to the traction frame 18 first, followed by engaging the bolt shafts of the tool frame 42 with the recesses in the connection member 50. To allow the weight of the tool frame 42 to be supported by the connection member 50 during the last step, one of the recesses would need to be configured so that it can be entered from the outer perimeter in a downwards direction. Because the tool frame 42 and the traction frame 18 are coupled together via one or more detachable connection members 50, the connection members 50 can be exchanged with differently configured connection members 50 such that the tool frame 42 is brought into a different position with respect to the traction frame 18 when the differently configured connection members 50 are used to couple the tool frame 42 and the traction frame 18. As a result of this different position, the tool frame 42 will be at a different vertical position and / or angular position relative to the traction frame 18, and hence the cutting reel and bedknife (or any other tool carried by the tool frame) will be at a different height and / or inclination angle relative to the ground. Figures 7 and 8 show plan views of two different connection members 50a, 50b for bringing the tool frame 42 into two different positions with respect to the traction frame 18. Each connection member 50a, 50b has a different overall spatial arrangement of engagement features 52a, 52b, 52c, 54a, 54b such that when the engagement features of the connection member 50a, 50b are engaged with their corresponding features 46a, 46b, 46c, 22a, 22b on the tool frame 42 and the traction frame 18, the tool frame 42 is in a different position with respect to the traction frame 18. In the present example, each connection member 50a, 50b comprises a first group of engagement features 52a-52c for engaging corresponding features 46a-46c of the tool frame 42 and a second group of engagement features 54a, 54b for engaging corresponding features 22a, 22b of traction frame 18. Within the first group, the spatial arrangement of the engagement features is the same for each connection member 50a, 50b. Within the second group, the spatial arrangement of the engagement features is the same for each connection member 50a, 50b. This is because the features 46a-46c, 22a, 22b of the tool frame 42 and the traction frame 18 that engage the engagement features have a fixed spatial arrangement with respect to their respective frames. However, what can differ between the different connection members 50a, 50b is the relative position of the first group relative to the second group. Comparing the connection member 50a shown in Figure 7 with the connection member 50b shown in Figure 8, it can be seen that the first group of engagement features 52a-52c of connection member 50b is positioned lower relative to the second group of engagement features 54a, 54b compared to connection member 50a. The first group of engagement features 52a-52c in connection member 50b is also positioned at a slightly different angular position relative to the second group of engagement features 54a, 54b compared to connection member 50a. The position of the fastening feature 56a relative to the first group of engagement features 52a-52c, and the position of the fastening feature 56b relative to the second group of engagement features 54a, 54b is also the same for both connection members 50a, 50b. Figures 9 and 10 showthe effect of exchanging connection member 50a with connection member 50b on the position of the tool frame 42 relative to the traction frame 18. In these figures, a vertical distance between the rotational axis of the cutting reel and a common arbitrary horizontal plane is labelled, and an inclination angle between a common arbitrary surface on the tool frame 18 and the common horizontal plane is labelled. It can be seen that exchanging connection member 50a with connection member 50b lowers the tool frame 18 relative to the traction frame 10 and hence decreases the height of the cutting reel 36 and bedknife 40 relative to the ground. The angular position of the tool frame 42 also changes relative to the traction frame 18 such that the inclination angle of the cutting unit 30 and hence the bedknife attitude angle decreases relative to the ground. Thus, by exchanging the connection member(s) 50 of the device with connection member(s) having a different overall spatial arrangement of engagement features, the vertical and / or the angular position of the tool frame 42 relative to the traction frame 18, and hence the height and inclination angle of a grass treatment tool mounted to the tool frame 42, can be changed in a fixed head grass treatment device. In the context of a fixed head mower with a reel cutting unit, the invention provides a plurality of connection members 50, each of which are configured (via the overall spatial arrangement of the engagement features) to position the cutting unit 30 at particular cutting height above the ground in combination with an optimal bedknife attitude angle for that cutting height. The user can thus conveniently choose and attach a connection member 50 that corresponds to a desired height of cut, which will simultaneously set the cutting unit 30 at an optimal inclination angle for that height of cut. The horizontal position of the tool frame 42 relative to the traction frame 18 can also be changed (optionally in combination with changing the vertical and / or angular position) by exchanging a connection member 50 with a different connection member 50 that has a different horizontal distance between the first group of engagement features and the second group of engagement features. Furthermore, the height adjustment mechanism 34 of the front roller 32 can be used to make further, finer adjustments to the height and the inclination angle of the cutting unit 30 relative to the ground after settingthe height and inclination angle with a particular connection member 50. Exchanging the connection members 50 can thus be used to provide “macro” adjustments to the height and inclination angle of the cutting unit 30 (because exchanging the connection members 50 allows the position of the tool frame 42 relative to the traction frame 18 to be changed), and the height adjustment mechanism 34 of the front roller 32 can be used to make “micro” adjustments (because adjusting the height of the front roller 32 can only move the coupled tool frame 42 and traction frame 18 as a single unit). The invention is not limited to using different connection plates 50 to set the tool frame 42 in different positions relative to the traction frame 18. In another example shown in Figure 11, the coupling structure for rigidly coupling the tool frame 42 to the traction frame 18 comprises a connection member 150, which can be provided as a pair of connection members 150 arranged on either side of the grass treatment device. The connection member 150 is attached to the tool frame 42 using at least one fastener (e.g. a bolt or screw) received through a corresponding aperture in the connection member 150 and an aligned aperture in the tool frame 42. The connection member further comprises a guideway 151 in the form of a slot defined in the connection member 150. As shown in Figure 11, more than one guideway 151 may be provided. The connection member 150 is attached to the traction frame 18 using a fastener 153 (e.g. a bolt or screw) that is received and retained in the guideway 151 and an aperture in the traction frame 18. When the fastener 153 is loosened (but still retained within theguideway), the tool frame 42 and the attached connection member 150 can be moved relative to the traction frame 18alonga path that is defined bythe guideway 151. To set the tool frame 42 in a particular position relative to the traction frame 18, the fastener 153 is tightened so that the tool frame 42 can no longer move relative to the traction frame 18, thereby rigidly coupling the tool frame 42 to the traction frame 18. The guideway 151 is configured such that movement of the tool frame 42 along path defined by the guideway 151 results in a change to the vertical and / or angular position of the tool frame 42 relative to the traction frame 18. The guideway 151 may be curved (e.g. arcuate) or linear. A plurality of exchangeable connection members 150 may be provided, each connection member 150 having a guideway 151 that defines a different path for changing the vertical and / or angular position of the tool frame 42 relative to the traction frame 18 in a different manner. As shown in Figure 12, the tool frame 42 and the traction frame 18 may comprise a plurality of interlocking teeth 155 to allow the position of the tool frame 42 to be adjusted relative to the traction frame 18 in predetermined increments defined bythe size and arrangement of the teeth. The interlocking teeth 155 also help to prevent inadvertent movement of the tool frame 42 relative to the traction frame 18 after the fastener 153 has been tightened. To allowthe toolframe 42 and the traction frame 18 to be moved relative to each other after the fastener 153 has been loosened, the guideway 151 and the aperture 157 in the traction frame 18 may be wide enough to allowthe tool frame 42 and the traction frame 18 to pulled apart slightly to disengage the interlocked teeth 155. To set the tool frame 42 in a new position relative to the traction frame 18, the tool frame 42 and the traction frame 18 are pushed back towards each other to re-engage the teeth and the fastener 153 is re-tightened. Instead of the connection member 150 and the traction frame 18 being attached via a fastener 153 received through the guideway 151, the connection member 150 and the tool frame 42 may be attached via a fastener received through the guideway 151. In this case, the connection member 150 remains rigidly attached to the traction frame 18 and the position of the tool frame 42 can be adjusted relative to the traction frame 18 and the attached connection member 150. Instead of providing the connection member 150 as a separate component to the tool frame 42 and the traction frame 18, the connection member 150 may instead be provided as an integral portion of the tool frame 42 or the traction frame 18. In each of the above examples, the position of the tool frame 42 relative to the traction frame 18 can be adjusted manually by the user. However, the position of the tool frame 42 could also be adjusted in an automated manner. In an example, the tool frame 42 is coupled to the traction frame 18 via a guideway which defines a path along which the tool frame 42 can travel relative to the traction frame 18. The grass treatment device further comprises a linear actuator configured to move the tool frame 42 along the path defined by the guideway. The guideway is configured such that movement of the tool frame 42 along path defined by the guideway results in a change to the vertical and / or angular position of the tool frame 42 relative to the traction frame 18. The guideway may be curved (e.g. arcuate) or linear. More than one guideway and more than one linear actuator may be provided to move the tool frame 42 in different directions relative to the traction frame 18. The grass treatment device further comprises a control system comprising a controller connected to the linear actuator. The controller and the linear actuator are connected to a power source. The controller is configured to send control signals to the linear actuator to control its linear displacement to move the tool frame 42 along the path by a particular distance. The control system may comprise an input device provided on the handle 16 or another component of the grass treatment device to allow the user to command the control system to move the tool frame 42 along the path by a desired distance. The control system may also be calibrated such that a user can input a desired height of cut, which will result in the linear actuator being controlled to move the tool frame 42 along the path to a particular position that will result in the cutting unit 30 being positioned at a particular height above the ground, and at an optimal inclination angle due to the path of the guideway. The invention thus provides a relatively quick and efficient way of maintaining a high quality of cut across a greater range of heights of cut in a fixed head mower because it provides a way to change the position of the cutting unit relative to the traction unit, which was not possible in traditional fixed head mowers. Although the invention has been described above in the context of a fixed head mower comprising a cutting unit for cutting grass, the invention is not limited to a grass treatment device that performs grass cutting. The cutting unit could instead be swapped out for other grass treatment tools in which the height and inclination angle of the grass treatment tool relative to the ground is important for optimal performance. An example of an alternative grass treatment tool that would benefit from the present invention is a turf cleaning unit which comprises a rotating brush and a comb. The comb is configured to lift debris from the grass and the rotating brush is configured to engage the comb to propel debris from the comb into a container. An example turf cleaning unit is disclosed in PCT publication no. WO 2019 / 109068 A1, which is hereby incorporated by reference in its entirety. It is important that the turf cleaning unit is positioned at the correct height and angle for the device to function properly and therefore a fixed head grass treatment device comprising the turf cleaning unit would benefit from the ability to set the turf cleaning unit at different heights and angles combinations provided by the present invention. Another example of an alternative grass treatment tool that would benefit from the present invention is a scarifierwhich typically comprises a plurality of blades mounted on a rotating shaft. As the shaft rotates, the blades cut channels into the turf and in doing so remove unwanted organic matter. Again, setting the scarifier at the correct height and angle is important for the scarifier to function properly and thus a fixed head grass treatment device comprising a scarifier would also benefit from the present invention. The tool frame 42 may conveniently be configured as a common frame on which different grass treatment tools (e.g. reel cutting unit, turf cleaning unit, scarifier unit) can be mounted and swapped. The grass treatment tools may be formed as cassettes or cartridges with a common mounting interface for releasably mounting to the same tool frame 42.

Claims

1. A grass treatment device system comprising:a grass treatment device comprising:a traction frame carrying a rear ground engaging member and a drive system configured to drive rotation of the rear ground engaging member; anda tool frame carrying a grass treatment tool and a front ground engaging member;the system further comprising a plurality of exchangeable connection members, each connection member being configured to rigidly couple the tool frame to the traction frame in a different position relative to the traction frame, wherein the vertical position and / or angular position of the tool frame relative to the traction frame is different in each position.

2. The grass treatment device system according to claim 1, wherein each connection member is removably attachable to the tool frame and to the traction frame.

3. The grass treatment device system according to claim 1 or claim 2, wherein each connection member comprises a plurality of engagement features, each engagement feature being configured to engage a corresponding feature on the tool frame or the traction frame, wherein when the engagement features are engaged with their corresponding features on the tool frame or the traction frame, the tool frame is set in a particular position relative to the traction frame.

4. The grass treatment device system according to claim 3, wherein the overall spatial arrangement of the engagement features is different for each connection member.

5. The grass treatment device system according to claim 3 or claim 4, wherein the plurality of engagement features comprises a first group of engagement features configured to engage with corresponding features of the tool frame and a second group of engagement features configured to engage with corresponding features of the traction frame, wherein the position ofthe first group of engagement features relative to the second group of engagement features is different for each connection member.

6. The grass treatment device system according to claim 5, wherein the spatial arrangement of the engagement features within the first group is the same for each connection member and the spatial arrangement of the engagement features within the second group is the same for each connection member.

7. The grass treatment device system according to any one of claims 3 to 6, wherein theplurality of engagement features comprises at least one aperture or recess configured to engage a corresponding protruding feature on the tool frame or the traction frame.

8. The grass treatment device system according to claim 7, wherein the plurality of engagement features comprises at least one recess extending inwardly from the outer perimeter of the connection member, and the at least one recess is configured to engage a corresponding protruding feature on the tool frame or the traction frame in a direction perpendicular to the longitudinal axis of the protruding feature.

9. The grass treatment device system according to any one of claims 3 to 8, wherein the connection member further comprises a plurality of fastening features arranged relative to the engagement features such that when the plurality of engagement features are engaged with their corresponding features on the tool frame and the traction frame, each fastening feature is aligned with a corresponding feature on the tool frame or the traction frame to receive a fastener to attach the connection member to the tool frame or the traction frame.

10. The grass treatment device system according to claim 9, wherein the plurality of fastening features comprises at least one aperture configured to align with a corresponding aperture in the tool frame or the traction frame.

11. The grass treatment device system according to any one of the preceding claims, wherein the plurality of connection members comprises a plurality of pairs of connection members arranged on opposing lateral sides of the grass treatment device.

12. The grass treatment device of any one of the preceding claims, wherein the tool frame further comprises a height adjustment mechanism configured to allowthe vertical position of the front ground engaging member to be adjusted relative to the tool frame.

13. The grass treatment device of any one of the preceding claims, wherein the grass treatment device is a mower and the grass treatment tool comprises a cutting reel and a bedknife for cutting grass.

14. A grass treatment device comprising:a traction frame carrying a rear ground engaging member and a drive system configured to drive rotation of the rear ground engaging member; anda tool frame carrying a grass treatment tool and a front ground engaging member;a coupling structure configured to rigidly couple the tool frame in a set position relative to the traction frame;wherein the coupling structure is further configured to allow the position of the tool frame to be changed and set in a different position having a different vertical position and / or angular position relative to the traction frame.

15. The grass treatment device according to claim 14, wherein the coupling structure comprises a connection member configured to set the tool frame ata particular vertical position and angular position relative to the traction frame, wherein the connection member is removably attached to the tool frame and the traction frame to allow the connection member to be exchanged with a different connection member to change and set the tool frame in a different position relative to the traction frame.

16. The grass treatment device according to claim 14, wherein the coupling structure comprises a guideway that defines a path along which the tool frame can move relative to the traction frame; and the guideway is configured such that movement of the tool frame along the 5 path changes the vertical position and / or angular position of the tool frame relative to the traction frame.

17. The grass treatment device according to claim 16, further comprising a linear actuator configured to move the tool frame along the path, and a control system comprising a controller 10 configured to control the linear actuator to move the tool frame a particular distance along the path.

18. The grass treatment device according to any one of claims 14 to 17, wherein the tool frame further comprises a height adjustment mechanism configured to allow the vertical position 15 of the front ground engaging member to be adjusted relative to the tool frame.

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