BLADE LEVELLING APPARATUS WITH PROVISION FOR MOUNTED ACCESSORIES

Abstract

The present invention is directed to levelling apparatus, typically as used on tractors, excavators and skid-steer vehicles, and references the levelling assembly and mounting options including directly to the existing blade of vehicles as well as other mounting arrangements. Preferred embodiments of a levelling apparatus include a blade body portion and body mounting portion connected by an arrangement of fixed and adjustable linkages, preferably hydraulic, to allow movement of the blade body portion (relative to the body mounting portion) in substantially an up and down direction, as well as rotational movement about an axis perpendicular to the general plane of an attached blade.

Claims

1. A blade leveling assembly comprising a body mounting portion and a blade body portion; said two body portions being connected by body connecting linkages which allow a substantially up and down vertical movement of the blade body portion, relative to the body mounting portion, and in which the inclination of a blade associated with the blade body portion remains substantially the same regardless of its vertical position; the body connecting linkages also allowing a rotational movement of the blade body portion, relative to the body attachment portion, about a rotational axis substantially perpendicular to the general plane of said blade; said body connecting linkages including linear actuators, there being at least one being present either side of the middle of the blade levelling assembly when viewed in plan; said body connecting linkages also including at least one pivot-ended stabilising linkage either side of the middle of the levelling assembly when viewed in plan; and wherein the body connecting linkages assist in maintaining relative movement of the body portions to within the rotational and vertical movements as defined above; there being provided on the blade body portion side supporting elements, positioned at the side edges of the blade body portion; said leveling assembly also including a rotatable accessory mounting portion in turn comprising a transverse accessory mount capable of at least partial rotation about an axis parallel to the general plane of the blade, said rotatable portion being positioned forward of the blade, and above the level of the blade, there being included mount rotation means controlling the rotational attitude of said transverse accessory mount.

2. A blade leveling assembly as claimed in claim 1 in which said rotatable accessory mounting portion extends between said side supporting elements and is mounted thereto.

3. A blade leveling assembly as claimed in claim 1 in which said side supporting elements comprise vertical side support guards positioned either side of the blade portion and extending forwardly thereof.

4. A blade leveling assembly as claimed in claim 1 in which said mount rotation means is capable of alternating said accessory mounting portion, with an attached assembly, between at least accessory retracted, and accessory engaged, positions.

5. A blade leveling assembly as claimed in claim 4 in which said mount rotation means comprises a linear actuator pivotably connected at one end to said transverse accessory mount, and to the blade body portion at its distal end.

6. A blade leveling assembly as claimed in claim 1 in which said mount rotation means is able to be engaged in a free mode, allowing substantially free rotation of the accessory when in an accessory engaged mode.

7. A blade leveling assembly as claimed in claim 1 in which affixed to said rotatable accessory mounting portion is a rotatable drum assembly.

8. A blade leveling assembly as claimed in claim 1 in which said rotatable drum assembly comprises drum side mounts to which a rotatable drum portion is connected, said drum side mounts connected to said transverse accessory mount and configured to act in conjunction with same to allow the arrangement to alternate between an accessory retracted position in which said rotatable drum portion is above the ground, as well as the level of the lowest edge of the blade assembly, and an accessory engaged position in which the drum is contactable, or in proximity, with the ground.

9. A blade leveling assembly as claimed in claim 8 in which said rotatable drum assembly includes drum power means for effecting powered rotation of said rotatable drum portion.

10. A blade leveling assembly as claimed in claim 9 in which said drum power means is positioned within the body of the drum.

11. A blade leveling assembly as claimed in claim 10 in which said drum power means comprises an inboard hydraulic motor positioned either end within the body of the drum.

12. A blade leveling assembly as claimed in claim 1 in which affixed or attachable to said rotatable accessory mounting portion is scarifier assembly comprising one or more scarifier modules comprising a plurality of tines.

13. A blade leveling assembly as claimed in claim 12 in which the arrangement of the transverse accessory mount and said scarifier modules is such that at least part of a scarifier module can bear against a scarifier support portion to its rear during operation in an accessory engaged mode.

14. A blade leveling assembly as claimed in claim 13 in which said scarifier support portion comprises either or both of the mouldboard portion and blade portion of the blade body portion.

15. A blade leveling assembly as claimed in claim 1 further characterized in that said body mounting portion and a blade body portion being connected by first and second sets of connecting linkages; said first set of two connecting linkages characterised by (i) when viewed in plan, being connected to said body mounting portion near its middle, (ii) when viewed in plan being connected to said blade body portion outwardly of its middle; said second set of two connecting linkages characterised by (i) when viewed in plan, being connected to said body mounting portion outwardly of its middle, and (ii) when viewed in plan being connected to said blade body portion outwardly of its middle, and by a distance substantially the same from the middle as its connection to said body mounting portion; and wherein either or both of said first and second set of linkages comprise adjustable length actuators.

16. A blade leveling assembly as claimed in claim 15 in which operation of said second set of linkages can effect changes in the pitch of the blade body portion.

17. A blade leveling assembly as claimed in claim 15 in which operation of said first set of linkages can effect changes in the yaw of the blade body portion

18. A blade leveling assembly as claimed in claim 5 in which said mount rotation means is able to be engaged in a free mode, allowing substantially free rotation of the accessory when in an accessory engaged mode.

Description

DESCRIPTION OF DRAWINGS

[0119] FIG. 1 is a partial plan view of one preferred embodiment of the present invention,

[0120] FIG. 2 is a perspective view of the embodiment of FIG. 1 in an alternative configuration,

[0121] FIGS. 3a, 3b, and 3c are front views of the embodiment of FIG. 1 with the blade lowered, raised, and inclined (about a forward axis), respectively,

[0122] FIG. 4 is a perspective view of an alternative embodiment of the present invention in a folded configuration,

[0123] FIG. 5 is a side diagrammatic view of the embodiment of FIG. 3,

[0124] FIG. 6 is a side diagrammatic view of FIG. 4 in an extended configuration,

[0125] FIG. 7 is a perspective view of the embodiment in FIG. 6,

[0126] FIG. 8 is a side diagrammatic view of a further embodiment of the present invention attached to the existing blade of a vehicle, and

[0127] FIG. 9 is a perspective view of the embodiment of FIG. 8,

[0128] FIG. 10 is a partial perspective view of an embodiment of a blade levelling assembly showing an embodiment of a rotatable accessory mounting portion, without fitted accessory, in an accessory retracted position,

[0129] FIG. 11 is a part side view of the embodiment of FIG. 10 with an embodiment of an accessory comprising a power drum fitted and in a position between retracted and engaged configurations,

[0130] FIG. 12 is a side perspective view of an embodiment of a blade levelling assembly with the embodiment of a power drum of FIG. 12 in an accessory engaged position,

[0131] FIG. 13 is a cross-sectional transverse plane diagrammatic view of a power drum as used in the embodiments of FIGS. 11 and 12,

[0132] FIG. 14 is a side perspective view of an embodiment of a blade levelling assembly illustrating laser guidance receivers and mounts,

[0133] FIG. 15 is a perspective view of an embodiment of a scarifier accessory module,

[0134] FIG. 16 is a top-side perspective view of an alternative embodiment of a blade levelling assembly showing a fixed transverse mount arrangement with an embodiment of a scarifier module, and an alternative embodiment of a forward support carriage arrangement,

[0135] FIG. 17 is a top side perspective view of a further embodiment of a blade levelling capable of yaw and pitch adjustment of the blade body portion.

[0136] FIG. 18 is a side diagrammatic view of the embodiment of FIG. 17 in which the blade body portion is pitched forwardly, and

[0137] FIG. 19 is a plan diagrammatic view of the embodiment of FIGS. 17 and 18 with wheels in folded position and in which the yaw of the blade body portion about a vertical z-axis has been adjusted.

DESCRIPTION OF PREFERRED EMBODIMENT

[0138] With reference to the drawings (particularly FIGS. 1 and 2), and by way of example only, there is provided a levelling assembly (generally indicated by arrow 1) comprising a body attachment portion (generally indicated by arrow 2) and a blade body portion (generally indicated by arrow 3);

[0139] the two body portions (2, 3) being connected by body connecting linkages (5-7) which allow a substantially translational movement of the blade body portion (3), substantially parallel and relative to the blade body portion (2)see for instance FIGS. 3a and 3b;

[0140] the body connecting linkages (5-7) also allowing a rotational movement of the blade body portion (3), relative to the body attachment portion (2), about a rotational axis substantially in the direction of forward travel (9) of the assembly (1)see for instance FIG. 3c;

[0141] said body connecting linkages including linear actuators (5a, b), there being at least one linear actuator (5) being present either side of the middle (10) of the levelling assembly (1) when viewed in plan;

[0142] said body connecting linkages (5-7) also including at least one pivot-ended stabilising linkage (6-7) either side of the middle (10) of the levelling assembly (1) when viewed in plan;

[0143] and wherein the body connecting linkages (5-7) assist in maintaining relative movement of the body portions to as described above.

[0144] The body attachment portion (2) includes a quick-hitch arrangement (4) such as commonly used on skid-steer tractors.

[0145] With reference to FIGS. 3 in the illustrated embodiment (1) there are two hydraulically controlled upper linear actuators (5a, b) which can be independently controlled to alter the relationship of each end of the blade portion (3) relative to the body attachment portion (2). This is best illustrated in FIG. 2, where right hand actuator (5b) is contracted relative to left hand actuator (5a) to adopt a configuration such as shown in FIG. 3c. While lower linkages (7) may comprise connecting arms, these may also comprise hydraulically controlled lower linear actuators which work in cooperation with actuators (5) to allow the blade body portion to adopt the configurations shown in FIGS. 3, and combinations thereof. This arrangement can also allow for alteration of the inclination of the blade (11) about a transverse axis, under the control of the operator.

[0146] The stabilising linkages, pivot-ended linkages (6a, b) (7a, b) have ball joint ends where they attach to at least one of the body portions (2, 3) which is necessary to allow for the permitted relative movements of the body portions (2, 3). In the present invention a spherical bush is used in the jointsthis joint (14) can be clearly seen in the stabilising arms (6) where they (in this embodiment) attach to a central mounting point (15) on the body mounting portion (2).

[0147] The geometry of the remaining connecting linkages (stabilising arms (6-7)) assist in maintaining the relationship between the two body portions (2, 3) as movement occurs (such as shown in FIG. 3). In this arrangement the distance of separation between the body portions (2, 3) remains substantially the same, as does their relative forward/rearward inclinations (i.e. inclination being rotation about a transverse axis) relative to each other (though some flexibility is allowed here in the design of the geometry in various embodiments).

[0148] The primary permitted relative movements between the body portions (2, 3) are, when viewed from the front and wherein the body attachment portion (2) is considered fixed in position, relative upward and downward movement of the blade body portion (3) relative to the body attachment portion (2), as well as allowing relative upward and downward movement of each end of the blade body portion (3) relative to the body attachment portion (2)allowing also for inclination of the blade portion (3) (relative to the body attachment portion (2)), such as shown in FIG. 2.

[0149] Accordingly there is provided a precise alteration of the elevation and rotational inclination of the blade relative to the quick hitch (4) (which follows the roll inclination of the vehicle in response to ground contours) without the need for heavy and expensive quick hitch rotational attachments. The arrangement of the illustrated embodiment theoretically provides for faster (quick response movements are important for a moving vehicle) changes to the elevation and rotational inclination of the blade, as well as being much more precise.

[0150] The actuators can also be coupled to a laser levelling control system (sensors or emitters can be mounted on arms (not shown) which fix at positions (12) on the blade portion (3)) so that the blade (11) is maintained at true ground elevation and the horizontal, regardless of any pitching and rolling movements of the vehicle to which it (1) is attached. As mentioned above, the quicker responsiveness of the present embodiment also allows the vehicle to travel faster.

[0151] Preliminary trials by the inventor, have indicated that the present invention when used with a laser levelling system can level ground to a much higher degree of precision (3 mm compared to 10 mm) approximately 12 times faster than when using a similar arrangement with a prior art device. This represents a very significant advance in the art in terms of productivity and precision. Accordingly this also opens the present invention up to other applications where a tool on a moving vehicle needs to be maintained at a precise inclination and elevation.

[0152] In FIGS. 4 and 5 we see a folding embodiment of the present invention, where a provided stabilising arm assembly (30) has a folding end portion (31) on which a ground contacting stabilising wheel arrangement (32) is mounted.

[0153] In FIG. 5 the reduced front to rear length of the apparatus is evident, as are the potential transport benefits. Similarly, the closer proximity of the blade (11) to the front of the apparatus, for close work, can be gauged.

[0154] In FIGS. 6 and 7 we see a further embodiment suitable for attachment to an excavator. Rather than a quick hitch (4) we have an arm arrangement (50) to which is pivotably attached (53) a T-pin (51) comprising a quick hitch adaptor (which may be of different quick connect configurations) to which the quick hitch adaptor (54) of an excavator's (not shown) dipper arm (52) may be attached. This arrangement makes the levelling assembly available for use with excavators, a new and novel arrangement which significantly improves the versatility of both excavators and levelling devices.

[0155] In FIGS. 8 and 9 we see an alternative mounting system to the ubiquitous quick hitch (4), the body mounting portion (70) attaching to the existing blade (71) of a vehicle (not shown for simplicity).

[0156] Here at least one upper hook portion (72) affixed to the body mounting portion (70) hooks over the top of the existing blade (71). A contacting bar (78) may be provided on the body mounting portion (70) to help accommodate the different curves of blades and reduce possible damage to the blade (71).

[0157] A lower hook portion (73) connected by a flexible linkage (74) to an adjustable linking element (75), in turn connected to an element (79) associated with the body mounting portion (70), helps secure the levelling assembly (1) to the existing blade (71) as the adjustable element(s) (75) are tightened. The adjustable element (75) may simply be a turnbuckle in a preferred element, and may be provided with an arm (76) to help tighten the turnbuckle, and provide additional stabilisation when the distal end of the arm (76) is connected to a point (77) on the blade body portion (3) after tightening.

[0158] In FIG. 10 we see an embodiment of a modified leveller assembly including a rotatable accessory mounting portion (101) comprising a transverse accessory mount (102), in simplest form comprising rectangular hollow section bar, connected at each end to side supporting elements (in this case comprising side guards) (106) by rotatable mounts (105) allowing at least partial rotation of the mount (102) about a transverse axis substantially in parallel with the general plane of the blade (11) or mouldboard (107) of the blade body portion.

[0159] Linkage tabs (104a,b) allow for control of the rotation of the mount (102) by allowing the connection of mount rotation means comprising linear actuators (103a,b). In preferred embodiments these are hydraulic and capable of progressive and continuous control by the operator, and/or could be linked into an automated control system. In this figure the mount (102) is shown in an accessory retracted position.

[0160] In FIGS. 11 and 12 we see the inclusion of a power drum assembly (generally indicated by arrow 110) such as a Harley rake (114) to the rear of structure support wheel (32). Features such as teeth or studs (115) may be provided on the Harley rake drum (114). While the invention allows for such an assembly (110) to be attached directly to side supports (106) by a rotatable mount (e.g. 105) at each end, the preferred arrangements utilise the rotatable transverse accessory mount (101) of the embodiment of FIG. 10 for easier fitment and removal of accessories (e.g. 110).

[0161] FIG. 12 provides a perspective view of the embodiment of FIG. 10 with the power drum accessory (110) of FIG. 11 (and such as detailed in FIG. 13) fitted and in the engaged position.

[0162] FIG. 13 illustrates a preferred power drum accessory (110) arrangement such as would be used in preferred embodiments as described in relation to FIGS. 11 and 13. As mentioned in the main body of the specification it is desirable for operators to be able to work close to boundaries and obstructionse.g. foundation walls, kerbing, marker poles, etc. In practice this can usually be achieved in embodiments of the invention by minimising protrusions outside of the width of the blade (11), or as more readily seen in the pictures, outside of the side guards 106.

[0163] While the power drum could utilise a compact external hydraulic motor at each end the option for preferred embodiments is predominantly inboard hydraulic motors (112a,b) positioned largely within the drum (114) itself. In this situation only the protective cap and mount (111a,b) need extend outside of the planes defined by the side guards (106) while allowing the drum (114) to extend the full width within the extended vertical planes defined by the side guards (106).

[0164] The protrusions (115) from the drum (114) are defined by choice, and may be replaceable elements or formed into drum (114) itself. The user is open to choice here. Various types of teeth, blades, features may be provided along with different combinations thereoffor instance the user choice for breaking asphalt and road-seal may be different from dethatching and preparing areas covered with vegetation.

[0165] Less destructive drum choices are also envisagedfor instance the power drum may comprise a brush for finishing and screeding areas, finishing landscaped areas or lightly covering sown seed, or even removing excess materials and debris on finished areas (e.g. gravel chips on finish tar sealed roading and sidewalks etc). It is intended that there will be user choice in the selection of the properties of the power drum in a power drum assembly (110).

[0166] FIG. 14 illustrates a different perspective view of the embodiment of FIG. 12, and also shows the laser receiver unit (116a,b) guide poles (117a,b) which can employed with various embodiments of a levelling assembly (1) to enable it to be used a laser guidance and levelling system, or full 3D guidance system, such as becoming more common in the industry. There are various manufacturers of such systems (including, for instance, Leica) which can provide accessory guidance and control systems able to work with position transmitters and solutions for use on various sites (and types of site). A potentially realisable advantage of various embodiments of the present invention is that when such laser assisted systems are used, any mounted accessories on the blade body portion also operate under the same laser assisted control as the blade and benefit from the advantages thereof. Hence a levelling assembly of the present invention to which various accessories can be fitted provides a useful advance in the industrythe multiple linkage arrangement connecting the blade body portion to the body attachment portion allows for angling of the accessory under operator control and/or in response to laser assisted control systems. No prior art accessories such Harley rakes/power drums, scarifiers, etc are able to be angled in response to changing ground contours and this represents a significant disadvantage (multiple passes with different accessories) in terms of time and accuracy for land and site preparation and contouring.

[0167] The following specifications in relation to the embodiments of FIG. 10 through 15 are not intended to be limiting but representative only of a currently most preferred embodiment, and to provide additional information to the skilled reader in understanding a best preferred embodiment of the invention. However, it should be appreciated that many of these parameters are open to user choice and to suit a particular job. [0168] Typical Drum diameter: 170 mm (without teeth) [0169] Typical Drum working width: 1.940 mm [0170] Drum type: Steel, reversible in operation without affecting levelling operation [0171] Typical Motor displacement (per side): 160-380 cc, depending on base machine size and hydraulic flow [0172] Typical Drum speed: adjustable from 0 to 240 RPM [0173] Typical Shaft diameter: 50 mm [0174] Typical Number of teeth: 96 [0175] Typical Tooth type: 16 mm tungsten with button or flat top, depending on type of work [0176] Typical Tooth height (from surface of drum): 30 mm [0177] Typical Type of drive: Direct with resilient internal toothed drive [0178] Typical Lubrication and maintenance points: zero, grease free pivots, internal, oil lubricated bearings [0179] Typical Drum support bearings: 2internal, oil lubricated, maintenance free [0180] Typical Angle of retraction: 90 degrees to operating plane [0181] Typical Engagement depth: Infinitely adjustable in operation from 100 above to 70 mm below blade height [0182] Typical Stone barrier set height: 3 position in 40 mm increments [0183] Typical Clearance height with drum removed: 560 mm [0184] Typical Drum forward length from blade: 540 mm [0185] Typical Drive motor extension width past side wing gusset: 20 mm [0186] Typical Weight of drum and mount structure: 200 KG [0187] Typical Weight of pivot mounting structure: 40 KG [0188] Typical Locking mechanism: Over centre latch mechanism with positive tension in lock position [0189] Typical Tilt from level: adjustable in manual or automatic mode, 0 to +/12 degrees [0190] Typical Control method: proportional hydraulic positioning using electronic machine control [0191] Typical Grade Control: continuous automatic from 2D laser or 3D data file, Dual GNSS or TPS capable [0192] Typical Tooth engagement depth: manual set via hydraulic cylinders [0193] Typical Maximum main fall: set by laser, typical 0-15% [0194] Typical Maximum cross fall: set by laser, typical 0-15% [0195] Typical Accuracy of cut: Typical +/3 mm from registered grade [0196] Typical laser system providerLeica

[0197] FIG. 15 illustrates another accessory which may be fitted by an operator to an accessory mount (102). In this case a scarifier module (121) comprises a plurality of tines (123) are connected to an accessory mount portion (122) for fitting to the transverse mount (102). A pivot pin(s) (not shown) aligned with axis 124 allows for forward pivoting of the tines (123) allowing for them to drag freely when the levelling assembly is being reversed in operation. Alignment pins (125a, b) maintain spacing of the tines.

[0198] Apertures (126) and (127) in the mount and tine portions respectively allow an operator to temporarily lift the tines (123) and place a pin in to lock them in an up position. This can be useful for improving visibility for the operator in certain operations where the tines are not required. This can still used in conjunction with rotation of the transverse mount (102) to further lift the tines (123).

[0199] Not visible is a rear tab or bar at the rear of the mount ribs (128) which limits rearward travel of the tines (123) during forward movement of the levelling assembly (1), and to allow the tines (123) of the module (121) to be raised when the accessory bar is moved to an accessory retracted position.

[0200] It should also be envisaged that the scarifier modules could be positioned directly in front of the blade and mouldboards of the levelling assembly to allow them to be used in conjunction with another accessory on a transverse accessory mount (102), allowing an operator to readily use both in conjunction or alternate between use of the two accessories with relative ease of operation and adjustment. It should also be appreciated that a single scarifier module extending the full width of the mount (102) could be used, or multiple smaller modules used as required.

[0201] FIG. 16 illustrates a further modification to various embodiments of the present invention. In practice it is sometimes necessary for operators to work around obstructions on a sitethese may be foundations for pillars or columns, and such like. As an alternative to the larger folding wheel carriage assembly (31, 32) of some embodiments of the invention, a simplified pivoting carriage with single pivot (132) can be provided and attached to a forwardly extending support (133), which may be fixed or removable. This arrangement gives a greater unobstructed distance (134) between the wheels (134) and projected general vertical plane of the side guards. This increased clearance make it easier for an operator to work close to, and around, obstructionspotentially providing a cleaner job with minimal manual follow up to finish problem areas. It should be noted that in a number of situations a forward carriage is desirable to help stop the levelling assembly (1) from nosing down into softer materials and maintaining a more accurate natural level for the tractor and levelling assembly combination.

[0202] As a variation of the aforesaid embodiments, there are occasionally situations where an operator may require additional flexibility in terms of being able to manipulate the orientation of the blade body portion (203). Such operations may include tilting the blade body portion forwardly or rearwardly (about a transverse axisi.e. altering the pitch of the blade body portion). Other operations may include rotating the angle of the blade body portion (203) about a vertical z axisi.e. a yaw type movement. And various combinations of these operations and that of previously described embodiments. It should also be appreciated that these operations also affect any accessories which may also be mounted on the blade body portion (203).

[0203] In order to achieve these additional operations, various linkages of the previous embodiments (e,g, FIG. 8) may be substituted with linear actuators.

[0204] FIG. 17 refers a modification of embodiments such as shown in FIG. 8. For instance, to achieve pitch adjustment, linkages (7) (e.g. FIG. 8) of the previous embodiments are substituted with linear (typically hydraulic) actuators (207). These can be lengthened or shortened (ideally in tandem) to adjust pitchwe shall assume that other linkages/actuators remain at constant length while visualising this. Once a desired pitch has been achieved, their length may be maintained to retain this relative pitch (though see also more sophisticated embodiments discussed later). The beauty of this arrangement is that the actuators (207) function primarily as adjustable linkages, enabling these variant embodiments (e.g. FIG. 17) to still operate in the manner of the embodiment of FIG. 1 (for instance).

[0205] Providing linear actuators (206) to replace linkages (6) of FIG. 1 allows for the aforesaid yaw-like adjustments to be made. Here the operation is a little different and will typically involve extending one actuator (206) while retracting the other (206). The geometry is also a little different and these actions may also cause some roll-movement of the blade body portion (203). While this might be acceptable in some embodiments, providing actuators (207) instead of fixed length linkages (e.g.7) can help compensate and allow adjustment to reduce these other pitch and/or roll changes when adjusting yaw.

[0206] In practice it is likely that an operator may employ changes to any one or more of pitch, yaw, and roll simultaneously. It is envisaged that in most cases the operation of such advanced embodiments of the present invention will be in conjunction with laser assisted control systemssuch as, for instance, provided by companies such as Leica. In these cases a control system for the actuators (205, 206, 207 where provided) will be coupled with the laser assisted control system to ensure the blade body portion (203) is maintained at the correct attitude/position as the leveller and vehicle travels across terrain.

[0207] It is envisaged that even with laser assisted embodiments, the operator may have direct (or indirect fly-by-wire type) control over pitch and yaw, as these are often more influenced by the type of terrain and material that the levelling assembly is working on. It also envisaged that these embodiments may also be used on non-laser assisted embodiments of a leveller assembly with direct control of the actuators (205-207 where provided) by the operator. There may also be fly-by-wire type assisted operation using computational means with a control system to enable the operator to more easily attain a particular attitude of the blade body portion (203)it is envisaged that such embodiments might even used modified joysticks or roller-ball type controls for the operator, rather than individual controls for each actuator and/or set thereof (i.e. 205-207 where provided).

[0208] FIG. 18 illustrates the embodiment of FIG. 17 in which actuators (207) have been shortened to enable the blade body portion to pitch forward relative to the ground (220)3. Once these actuators (207) have been set and maintained at the required length, and assuming also that actuators (206) are also maintained at constant length (assuming these are present instead of linkages (6)) then operation of actuators (205) will raise and lower the blade body portion (203) while maintaining substantially the same pitch. In fact, operation of actuators will be substantially the same in effect as for the embodiment of FIG. 1.

[0209] FIG. 19 illustrates the embodiment of FIG. 10 where the yaw (rotation about vertical z-axis) has been adjusted. Here, due to the geometry of the actuators, this also involves some adjustment of all the actuators (205, 206, 207) and not just actuators (206). The operations of raising, lowering, and roll such as illustrated in FIGS. 3 are still possible though some additional adjustment to actuators (206, 207) may be required in addition to operation of actuators (205) if relative pitch and yaw attitudes are to be accurately maintained.

[0210] It should be envisaged that the embodiments of FIGS. 17 through 19 may also be further modified with the retractable mounting arrangements of figures

[0211] Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the spirit or scope of the present invention as described herein.

[0212] It should also be understood that the term comprise where used herein is not to be considered to be used in a limiting sense. Accordingly, comprise does not represent nor define an exclusive set of items, but includes the possibility of other components and items being added to the list.

[0213] This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being authoritative disclosure on the true state of the prior art but rather as referencing considerations brought to the mind and attention of the inventor when developing this invention.