Excavator vehicle

The present invention relates to an excavator vehicle, kits for the production of an excavator vehicle and a kit for the production of an attachment for an excavator vehicle.

Excavator vehicle are well-known to those skilled in the art. Many of these are designed to operate in wide chambers, not least because wide chambers are generally more economically viable than narrow chambers. It is, however, sometimes desirable to work in narrow chambers, especially when the price of the material being excavated warrants working in a narrow chamber. There are many potential problems associated with operating in a narrow chamber. It may be difficult to move a vehicle, and therefore moving a vehicle, for example backwards and forwards to move a material-collecting vehicle apron may be difficult or impossible. Furthermore, vehicles specifically designed to operate in small, narrow chambers ma be generally less effective for use in wider chambers. Workin in a narrow chamber may present greater safety concerns than working in a wide chamber, not least when an operator tries t leave the vehicle. Narrow chambers may be tilted laterally, for example, and this may cause excavators to tip sideways. Narrow chambers may have a steep incline or decline and this can present problems in removing excavated material. The excavator vehicle of the present inventions seeks to

ameliorate one or more of the problems mentioned above.

In accordance with a first aspect of the present invention, there is provided an excavator vehicle comprising: a first means for moving the excavator vehicle, the first means being associated with the left side of the excavator vehicle; and a second means for moving the excavator vehicle, the second means being associated with the right side of the excavator vehicle, the first means being attachable in a wide operating position and in a narrow operating position, and the second means being attachable in a wide operating position and in a narrow operating position.

The excavator vehicle of the first aspect of the present invention provides a vehicle which is adaptable to operate in narrow chambers and in wider chambers.

For the avoidance of doubt, it is hereby stated that the first and second means are releasably attachable in the wide and narrow operating positions. In operation, the first means and second means may be attached in ^■ the narrow or wide operating positions. Then, the first means and second means may be moved to the other of the narrow and wide positions, and attached in the other of the narrow and wide positions.

One or both of the first and second means for moving the excavator may comprise one or more ground-contacting wheels. One or both of the first and second means for moving the excavator may comprise one or more ground-contacting tracks.

If the first means is attached in the wide position, then the second means is typically attached in the wide position.

Conversely, if the first means is attached in the narrow position, then the second means is typically attached in the n arrow position.

The first and second means for moving the vehicle may each be configurable in a first configuration for engaging ground beneath the excavator vehicle (such as a chamber floor) and a second configuration for engaging the ground to the side of the excavator (such as a chamber wall) . It is typical for both of the first and the second means to be configured in the first configuration, or for one of the first and fourth means to be in the first configuration and the other of the first and fourth means to be in the second configuration. Whilst possible, it would be unusual for both the first and fourth means to be in the second configuration.

The excavator may comprise an excavator attachment for moving excavated material. For example, the excavator attachment may comprise a bucket or scoop for moving excavated material.

The excavator may comprise an excavator attachment for excavating material from a substrate. For example, the excavator attachment may comprise a cutter, such as a rotary cutter. The excavator attachment may comprise a cutter and a bucket or scoop for moving excavated material. Such an attachment may be used to both cut material from a substrate and to move excavated material (typically for collection by the excavator) .

The excavator may comprise an excavator frame for supporting one or more excavator components. When the first means and second means are in the narrow positions, then the first means and second means may be inwards of the frame. When the first means and second means are in the wide positions, then the first means and second means may be outwards of the frame.

This arrangement provides an adaptable excavator which is capable of operating in narrow and wide chambers.

The excavator may comprise an apron for the collection of excavated material. The apron may optionally forward- projecting apron. The apron may optionally be operable between a contracted operational configuration and an expanded operational configuration.

The excavator of the present invention may be advantageously used in both narrow and wide chambers and seams. Furthermore, the ability to expand the apron means that, when working in narrow seams, it is possible to present a larger apron for collection of material and therefore it may not be necessary to re-position the apron by moving the vehicle backwards and forwards (which may not be possible in a narrow chamber) . The contracted operational configuration is typically a narrow configuration. The expanded operational configuration is typically a wide configuration.

The surface area of the apron in the expanded configuration may be greater than the surface area of the apron in the contracted configuration.

The apron may comprise a central portion and at least one side portion (and optionally two side portions) . At least one side portion (and optionally two side portions) may be movable relative to the central portion. If the apron comprises two side portions, the central portion is typically located between two side portions. The side portion (s) may be movable relative to the central portion between the contracted

operational configuration and the expanded operational

configuration. Each of the side portions may rotate between the contracted and expanded operational configurations. The side portion (s) may optionally be pivotally mounted for rotation relative to the central portion. Optionally, an edge of each side portion is proximate to an edge of the central portion. Each side portion may optionally be associated with a means for moving the side portion. The means for moving the side portion may optionally comprise a variable length member. The variable length member may be in the form of a piston. Varying of the length of the variable length member typically causes movement of the side portion relative to the non- movable central portion.

The excavator may be provided with an aperture for receiving excavated material from the apron, the aperture being provided in proximity to a conveyor for moving excavated material.

Typically, excavated material is collected on the apron and is passed through the aperture to the conveyor. The central portion of the apron may optionally extend forward from said aperture. The side portions of the apron may typically extend to the side of the aperture. In this way, the apron may inhibit loss of excavated material and may direct excavated material into said aperture. The excavator may optionally be provided with a material-deflecting surface to the rear of said aperture. This surface may encourage excavated material to enter the aperture.

The apron may typically have a front edge, the front edge being shorter when the apron is in the contracted

configuration than when the apron is in the expanded

configuration .

The apron may comprise one or more movable plates.

The apron may comprise at least two plates, at least one of which is typically movable. Two or more plates may at least partially overlap, at least when the apron is in the

contracted configuration and optionally when the apron is in the expanded configuration. The overlap of the plates provides the apron surface for the collection of excavated material.

The apron may optionally comprise three plates, two of which are movable relative to the third plate. Optionally, the two movable plates at least partially overlap with the third plate. The third plate is typically a central plate, and the two movable plates comprise two lateral plates, one to either side of the central plate. The two lateral plates may be arranged for pivotal movement. The degree of overlap between a lateral plate and the central plate depends on whether the apron is in a contracted configuration or an expanded

configuration. The two lateral plates may optionally be movable independently of each other. This may be advantageous, for example, if it is undesirable to move one of the lateral plates. Alternatively, the two lateral plates may not be movable independently of one another. This may provide an excavator which is simpler to operate and which is cheaper.

The apron may be provided with at least one (and preferably at least two) walls for retaining excavated material on the apron. The apron may comprise two lateral edges, a wall being provided on each of the two lateral edges. At least one wall may extend rearwardly from the front edge of the apron.

If the apron comprises three plates (two of which are movable relative to the third plate) , then a wall may be provided on each of the two plates which are movable relative to the third plate. If the two movable plates comprise lateral plates, a wall may be provided on each lateral plate. At least one (and preferably both) of the walls may optionally be pivotally attached to an excavator structure to facilitate pivotal movement of the wall and associated plate.

It has been discovered that providing the mounting point on the wall (as opposed to on the plate) decreases the risk of the apron becoming jammed by excavated material and therefore becoming inoperable. The apron may be provided with a central portion and two or more lateral portions, the lateral portions being movable relative to the central portion. The lateral portions may be arranged for pivotal movement. At least one and preferably each lateral portion may comprise a base portion which at least partially overlaps with the central portion when the apron is in the contracted configuration (and optionally at least partially overlaps with the central portion when the apron is in the expanded configuration) . At least one and preferably each lateral portion may comprise a wall portion for retaining excavated material on the apron. At least one (and preferably both) of the wall portions may optionally be pivotally attached to an excavator structure to facilitate pivotal movement of the respective lateral portion.

A variable length member may be provided for moving one of the movable plates or movable lateral portions. The variable length member may be in the form of a piston. One end of the variable length member may be attached to the movable plate or movable lateral portion and the other end of the variable length member may be attached to the non-movable plate (or non-movable central portion) . Attachment of the ends of the variable length member may be pivotal. Varying of the length of the variable length member typically causes movement of the movable plate or lateral portion relative to the non-movable plate or central portion.

The excavator may comprise an excavator vehicle, main body. The excavator may comprise an excavator arm for attachment to the main body, the arm being attachable to an excavator attachment. The excavator may also comprise and an elongate beam for attachment to the excavator main body, the elongate beam being operable to move an excavating attachment along the longitudinal axis of the beam. The excavator may typically operate with the excavator arm or the beam. The arm may typically be used for driving a heading into a chamber, and the beam may typically be used to excavate material which is out of reach of the excavating attachment attached to the arm.

Those skilled in the art will realise that the elongate beam is not necessarily provided with an excavating attachment, merely that the beam is operable to move an excavating

attachment in the described manner, if an attachment is fitted to the beam.

The excavator may be provided with an excavator attachment which is suitable for attachment to the arm and one which is suitable for attachment to the beam. The one which is suitable for attachment to the beam may comprise a T-shaped attachment, optionally comprising a central portion for attachment to the beam and cutting portions either side of the central portion. The excavator attachment suitable for attachment to the arm may comprise a cutter portion for cutting material from a substrate and a bucket portion for collecting excavated material .

The arm may have a first arm portion which may be pivotally attachable to the excavator main body, and a second arm portion pivotally attached to the first arm portion. The arm may further comprise a third arm portion pivotally attached to the second arm portion. The second arm portion may be

pivotally attachable to an excavating attachment. The third arm portion may be pivotally attachable to an excavating attachment .

The beam may be operable to move an excavating attachment along the length of the beam.

The excavator vehicle may comprise, or be connectable to, a power pack for powering the excavator vehicle thereby

rendering the vehicle operable. The excavator vehicle may comprise a seat for an operator.

Movement of at least part of the seat in a pre-determined manner may cause at least part of the excavator vehicle to be inoperable .

It is occasionally necessary to leave the excavator vehicle in a hurry. The applicant has found that it is desirable to provide a mechanism to disable at least part of the excavator vehicle before leaving the vehicle, a process which may otherwise bring the leaving user into close proximity with parts of the excavator, the movement of which may be

undesirable when the operator is in proximity.

Those skilled in the art will realise that movement of the at least part of the seat may well, of course, render the seat inoperable. The at least part of the excavator which is caused to be inoperable is not the seat.

Those skilled in the art should recognise that not all movements of the seat necessarily render the excavator vehicle (or part thereof) inoperable. For example, the seat (or part thereof) may be adjustable to suit the size of the user. For example, seat may be movable in a forwards/backwards direction and/or in an up/down direction to suit the size of the operator .

Said movement of the seat or part thereof in said predetermined manner may create an escape path for the operator in the event of an emergency.

The seat may comprise a seat back. The seat back may

optionally be moveable in said pre-determined manner to cause at least part of the excavator vehicle to be inoperable, for example, by folding the seat back forwards or backwards. Alternatively, the seat back may be removable so as to cause at least part of the excavator vehicle to be inoperable.

The seat may be associated with a vehicle main body. The power pack, if present, may be located remote from the vehicle main body.

The excavator may optionally be powered by a fluid, for example being hydraulically powered or being powered by liquid fuel, and therefore the power pack may comprise a means for providing fluid to the excavator vehicle. In this case, the excavator vehicle may comprise a valve, operable between first and second states, wherein in the first state a first flow path is established to permit fluid to be transmitted to the vehicle (or part thereof) so that the vehicle (or part thereof) is operable, and in the second state there is no flow path to the excavator (or part thereof) so that the excavator (or part thereof) is inoperable. In this case, said, predetermined movement of the seat (or part thereof) causes the valve to be in the second state. The connection between the seat (or part thereof) and the valve may be provided by one or more of one or more cables, one or more rods or a cam. In the second state, a flow path may be established to a return fluid circuit so that pressure does not build-up in a hydraulic circuit .

The excavator may optionally be electrically powered, and therefore the power pack may comprise means for providing electrical energy to the excavator vehicle. In this case, the excavator vehicle may be provided with a switch for cutting power to the excavator vehicle (or part thereof) , said predetermined movement of the seat (or part thereof) causing the switch to be actuated. Those skilled in the art will realise that causing the excavator (or part thereof) to be inoperable does not

necessarily mean that power is cut from the excavator (or part thereof) . For example, the pre-determined movement of the seat (or part thereof) could disengage part of the excavator from a driving mechanism so that the disengaged part no longer moves. For example, said pre-determined movement may disengage a conveyor from the driving mechanism by the use of a clutch which may be disengaged when the seat is moved. The excavator vehicle may have a front and a rear, said predetermined movement of the seat (or part thereof) renders inoperable at least one component of the excavator vehicle which is located at least partly to the rear of the seat. In this connection, the excavator may optionally comprise a conveyor which may optionally extend to the rear of the seat. The pre-determined movement of the seat (or part thereof) may cause the conveyor to stop. This is particularly advantageous when the conveyor comprises an auger or screw conveyor since placement of feet into an operating auger conveyor would be bad.

The seat may be provided with a locking mechanism. The locking mechanism may be operable between a first state in which said movement of the seat (or part thereof) is resisted and a second state in which said movement of the seat (or part thereof) is not resisted. Alternatively, the locking mechanism may comprise a frangible locking portion. Such a locking portion may be broken on the application of a considerable force to the seat (or part thereof) .

When the seat is ready for use it may be considered to be in a deployed position. If the seat is in the deployed position, then the excavator (or part thereof) is operable. Returning the seat into the deployed position from the state in which the excavator (or part thereof) is inoperable may make the vehicle (or part thereof) operable once more (subject to the actuation of any other safety features as is discussed below) .

The excavator may be provided with further safety features, for example, a dead man's switch should cause the excavator to be inoperable in the event that the dead man' s switch is released. The dead man's switch may comprise a pedal. If pressure is lifted from the pedal, then the switch excavator becomes inoperable. However, such dead man's switches are not fool-proof and may fail, and therefore the present invention provides an additional safety feature to reduce the risk to the operator.

The excavator may comprise a conveyor for moving excavated material. The conveyor may comprise a rotatable screw for moving excavated material. The screw may be at least partially disposed within an enclosure. The enclosure may be provided with an aperture for egress of excavated material. The

enclosure may be provided with a movable aperture-defining portion for adjusting the size and/or the position of the aperture.

The ability to adjust the position of the aperture enables the conveyor to deliver excavated material efficiently to a collection point.

The enclosure is typically provided to retain the excavated material in close proximity to the screw so that the screw may move the excavated material.

The conveyor may be considered to have a longitudinal axis parallel to the screw axis. The aperture defining portion may be movable so as to vary the angular position of the aperture relative to the longitudinal axis of the conveyor. This may be of particular use when the excavator is working when on a tilt. For example, the movable aperture defining portion may comprise a rotatable sleeve provided with an aperture, the sleeve being rotatable so as to vary the angular position of the aperture relative to the longitudinal axis of the

conveyor. Alternatively or additionally, the moveable aperture defining portion may comprise one or more movable shutters, operable to define an aperture for the egress of excavated material, the shutters being moveable to vary the angular position of the aperture relative to the longitudinal axis of the conveyor. The one or more moveable shutters may also be movable to vary the size of the aperture.

The conveyor is typically elongate. The enclosure is typically in the form of a housing. The housing may be cylindrical, typically in the form of a right circular cylinder. The aperture for egress of excavated material is typically located at or near one end of the conveyor. The conveyor typically has a front associated with the front of the excavator vehicle and a rear associated with the rear of the excavator vehicle, the aperture for egress of excavated material being located closer to the rear of the conveyor than the front of the conveyor. The excavator vehicle typically comprises an excavator main body having a front and a rear. The conveyor typically extends past the rear of the excavator main body. This enables a receptacle or removing conveyor (not being the conveyor mentioned above) to be placed so as to receive excavated material from the conveyor of the excavator of the present invention. The conveyor of the excavator of the present invention may be movable so as to vary the angle of pitch of the conveyor.

The excavator of the present invention may comprise an apron for the collection of excavated material, the conveyor being located so as to receive excavated material from the apron. The apron is typically located forward of the conveyor.

The excavator may comprise an excavator attachment comprising a first excavator attachment portion comprising a scoop, and a first cutter device of a first type for excavating rock or the like, the first cutter device being interchangeable with a second cutter device of a second type.

The scoop may be in the form of a bucket.

The first excavator attachment portion may comprise a first configuration for mating with a corresponding configuration provided on the first and second cutter devices. For example, the first configuration may be in the form of a female configuration for receipt of a male configuration provided on the first and second cutter devices. Alternatively, the first configuration may be in the form of a male configuration for insertion into a female configuration provided on the first and second cutter devices. The female configuration may be in the form of a recess. The male configuration may be in the form of a protrusion. The first cutter device may optionally comprise a single rotary cutter of elongate configuration mountable to the first excavator attachment portion so that the cutter device has a proximal end associated with the scoop and a distal end remote from the scoop. The second cutter device may optionally comprise two rotary cutters. The second cutter device may comprise a T-shaped device.

The excavator may be provided with a third means for moving the vehicle, said third means for moving the vehicle being associated with an upper part of the vehicle. The third means for moving the vehicle may advantageously engage with a roof or wall of a chamber. This may be of particular use in the event that the chamber is laterally tilted (as sometimes happens for a narrow chamber) in which case the third means for moving the vehicle may be arranged to engage the wall of the chamber.

The excavator may comprise a fourth means for moving the vehicle, the fourth means for moving the vehicle being associated with an upper part of the vehicle.

The excavator may be provided with a cab for the protection of the operator or a roof. The third means (and fourth means, if present) for moving the vehicle may optionally be attached to the cab or the roof.

The third means for moving the vehicle may be located to the left or right hand side of the excavator (as opposed to being located on a centre line of the excavator) .

If a fourth means for moving the vehicle is present, then the third means for moving the vehicle may be located to one or the left or right hand side of the vehicle and the fourth means for moving the vehicle may be located to the other of the left or right side of the vehicle.

The third means (and fourth means, if present) for moving the vehicle typically comprises a surface for contacting the ground so as to enable movement of the vehicle. The third (and fourth means, if present) for moving the excavator may be arranged so that said surface is for contacting ground beneath the excavator or to the side of the excavator. In narrow chambers or in chambers which are tilted, it may be desirable for a wheel or track surface to contact a chamber wall, as opposed to a chamber floor. The first means and second means for moving the vehicle typically comprises a surface for contacting the ground so as to enable movement of the vehicle. The first and second means for moving the excavator may typically be arranged so that said surface is for contacting ground beneath the excavator. However, the first and second means for moving the excavator may be arranged so that said surface is for contacting ground to the side of the excavator.

The first means, second means, third means and fourth means for moving the vehicle may comprise a caterpillar track, for example .

The first means, second means, third means (if present) and fourth means (if present) for moving the vehicle may each be ^' individually selected from a ground-engaging track arrangement (such as a caterpillar track arrangement) and a set of one or more ground-engaging wheels. The first aspect of the present invention therefore provides: an excavator vehicle comprising: a first ground-engaging track arrangement or a first set of one or more ground-engaging wheels, the first ground-engaging track arrangement or the first set of one or more ground engaging wheels being associated with the left side of the excavator vehicle; and a second ground-engaging track arrangement or a second set of one or more ground-engaging wheels, the second ground-engaging track arrangement or the second set of one or more ground engaging wheels being associated with the right side of the excavator vehicle; the first ground-engaging track arrangement or the first set of one or more ground-engaging wheels being attachable in a wide operating position and in a narrow operating position, and the second ground-engaging track arrangement or the second set of one or more ground-engaging wheels second means being attachable in a wide operating position and in a narrow operating position.

The excavator vehicle may comprise a single, single-width track arrangement for engaging ground beneath the excavator vehicle, the single-width track arrangement being operable to move the excavator vehicle.

The single-width track arrangement facilitates the production of a very narrow vehicle that may be used in very confined spaces. Furthermore, it has been found that using a dual-width track arrangement in which there are two tracks side-by-side has caused unexpected problems. For example, spoil may accumulate between the two tracks and cause jamming of one or both of the two tracks, which may cause the machine to "crab" sideways and/or for damage to be caused to the gearbox. For the avoidance of doubt, in this particular embodiment, the excavator vehicle has only one single-width track arrangement for engaging ground beneath the excavator vehicle to move the vehicle, and no other vehicle-moving track arrangement for engaging with the ground beneath the vehicle. As mentioned below, the excavator vehicle may be provided with powered tracks or other ground-engaging means (such as powered wheels) for engaging ground to the sides of the excavator vehicle and/or above the excavator vehicle.

The single-width track arrangement may comprise a single track for engaging ground beneath the vehicle. Alternatively, the single-width track arrangement may comprise a plurality of tracks, mutually spaced along the length of the single-width track arrangement .

The single width track arrangement may optionally be less than lm wide .

The excavator vehicle may comprise a vehicle main body located beneath which the single-width track arrangement is located. The word "beneath" is indicative of the position of the single-width track arrangement when the excavator vehicle is in an upright orientation. The single-width track arrangement may optionally extend along the length of the vehicle main body.

The single-width track arrangement may optionally be located laterally centrally in relation to vehicle main body.

The excavator vehicle may comprise a motor for powering the track (s) of the single-width track arrangement, and optionally a gear box associated with said motor and said track (s) of the single-width track arrangement. The. gear box and motor are optionally provided as part of a module which is removably attached. This facilitates the quick removal of the module to service and fix any problems in said gear box or motor. The module may be removably attached to a chassis unit comprising rollers for guiding the track. The module may be attached to the chassis unit using bolts and the like which facilitate removal of the module. The module may be located at or near one end of the single-width track arrangement. The module may be located towards or at the rear of the vehicle. This facilitates relatively easy access to the module. The module may be, in normal use, located within a space defined by a track of the single-width track arrangement.

The single-width track arrangement engages ground beneath the excavator vehicle. The excavator vehicle may optionally be provided with one or more powered tracks (or other ground- engaging means, such as wheels) for engaging ground to the side of the excavator, or above the excavator. Optionally, the excavator vehicle may be provided with one or more of : a powered track (or other ground-engaging means) for engaging ground to one lateral side of the excavator (say, the left), a powered track (or other ground-engaging means) for engaging ground to another lateral side of the excavator (say, the right) , and a powered track (or other ground-engaging means) for engaging ground above the excavator. A powered track (or other ground-engaging means) for engaging ground to a lateral side of the excavator vehicle may be attachable to the

excavator main body in a plurality of positions. For example, the powered track (or other ground-engaging means) may be attachable to the excavator main body in a first position and in a second position, the first position bei-ng above- the — second position when the excavator is in an upright

orientation. Additionally or alternatively, the powered track (or other ground-engaging means) may be attachable to the excavator main body in a forward position and an aft position.

The excavator vehicle may optionally be provided with one of more ground-contacting supports, such as one or more skids or rollers. Such supports may contact the ground and provide support to the excavator vehicle, but typically do not assist in the routine forwards and backwards movement of the

excavator vehicle. One or more support may be provided for contacting ground beneath the excavator vehicle, but to one lateral side of the vehicle. The vehicle may be provided with one or more supports for contacting ground beneath, but to one lateral side of, the vehicle and one or more supports for contacting ground beneath, and to another lateral side of, the vehicle. Therefore, the vehicle may be provided with a support which contacts the floor of a chamber to the left of the vehicle main body, and a support which contacts the floor of the chamber to the right of the vehicle main body. Such an arrangement may help prevent the excavator from tipping over. One or more support may be provided for contacting ground to one lateral side of the vehicle and one or more supports may be provided for contacting ground to another lateral side of the vehicle.

One or more of the ground contacting supports may be

retractable or removably attachable to a ground-contacting support mount. Said mount may optionally be removably attached to the vehicle main body. In very confined environments, such as very narrow seams, there will be no room for said supports.

One or more ground-contacting support mounts may be arranged to receive a lifting arrangement (such as a jack or ram) . The lifting arrangement may be interchangeable with a ground- contacting support. The support (such as a skid or rollers) would be removed and replaced by the lifting arrangement. Such a lifting arrangement may be used to support the excavator vehicle, should any work need to be performed on said vehicle. Alternatively or additionally, the lifting arrangement may be used to free-up the vehicle, should it become stuck or jammed, as may happen occasionally in the environments in which the excavator vehicle typically works.

The excavator vehicle may be provided with one or more

laterally-extensible rams. The one or more rams may be

operable to contact a wall to the side of the excavator vehicle. The rams may be used to free-up the vehicle if it has become stuck or jammed. A first lateral side of the excavator vehicle may be provided with one or more rams and a second lateral side of the excavator vehicle may be provided with one or more rams . In accordance with a second aspect of the present invention, there is provided an excavator vehicle comprising a forward- projecting apron for the collection of excavated material, the apron being operable between a contracted operational

configuration and an expanded operational configuration.

The excavator of the present invention may be advantageously used in both narrow and wide chambers and seams. Furthermore, the ability to expand the apron means that, when working in narrow seams, it is possible to present a larger apron for collection of material and therefore it may not be necessary to re-position the apron by moving the vehicle backwards and forwards (which may not be possible in a narrow chamber) .

The excavator vehicle may further comprise an attachment for moving excavated material towards the apron. The attachment may comprise a portion for excavating material from a

substrate .

The surface area of the apron in the expanded configuration may be greater than the surface area of the apron in the contracted configuration. The contracted operational configuration is typically a narrow configuration. The expanded operational configuration is typically a wide configuration.

The apron may comprise a central portion and at least one side portion (and optionally two side portions) . At least one side portion (and optionally two side portions) may be movable relative to the central portion. If the apron comprises two side portions, the central portion is typically located between two side portions. The side portion (s) may be movable relative to the central portion between the contracted operational configuration and the expanded operational configuration. Each of the side portions may rotate between the contracted and expanded operational configurations. The side portion (s) may optionally be pivotally mounted for rotation relative to the central portion. Optionally, an edge of each side portion is proximate to an edge of the central portion. Each side portion may optionally be associated with a means for moving the side portion. The means for moving the side portion may optionally comprise a variable length member. The variable length member may be in the form of a piston. Varying of the length of the variable length member typically causes movement of the side portion relative to the non- movable central portion.

The excavator may be provided with an aperture for receiving excavated material from the apron, the aperture being provided in proximity to a conveyor for moving excavated material.

Typically, excavated material is collected on the apron and is passed through the aperture to the conveyor. The central portion of the apron may optionally extend forward from said aperture. The side portions of the apron may typically extend to the side of the aperture. In this way, the apron may inhibit loss of excavated material and may direct excavated material into said aperture. The excavator may optionally be provided with a material-deflecting surface to the rear of said aperture. This surface may encourage excavated material to enter the aperture. The apron may typically have a front edge, the front edge being shorter when the apron is in the contracted

configuration than when the apron is in the expanded

configuration .

The apron may comprise one or more movable plates. The apron may comprise at least two plates, at least one of which is typically movable. Two or more plates may at least partially overlap, at least when the apron is in the contracted configuration and optionally when the apron is in the expanded configuration. The overlap of the plates provides the apron surface for the collection of excavated material. The apron may optionally comprise three plates, two of which are movable relative to the third plate. Optionally, the two movable plates at least partially overlap with the third plate. The third plate is typically a central plate, and the two movable plates comprise two lateral plates, one to either side of the central plate. The two lateral plates may be arranged for pivotal movement. The degree of overlap between a lateral plate and the central plate depends on whether the ^' apron is in a contracted configuration or an expanded

configuration. The two lateral plates may optionally be movable independently of each other. This may be advantageous, for example, if it is undesirable to move one of the lateral plates. Alternatively, the two lateral plates may not be movable independently of one another. This may provide an excavator which is simpler to operate and which is cheaper. The apron may be provided with at least one (and preferably at least two) walls for retaining excavated material on the apron. The apron may comprise two lateral edges, a wall being provided on each of the two lateral edges. At least one wall may extend rearwardly from the front edge of the apron. If the apron comprises three plates (two of which are movable relative to the third plate) , then a wall may be provided on each of the two plates which are movable relative to the third plate. If the two movable plates comprise lateral plates, a wall may be provided on each lateral plate. At least one (and preferably both) of the walls may optionally be pivotally attached to an excavator structure to facilitate pivotal movement of the wall and associated plate. It has been discovered that providing the mounting point on the wall (as opposed to on the plate) decreases the risk of the apron becoming jammed by excavated material and therefore becoming inoperable.

The apron may be provided with a central portion and two or more lateral portions, the lateral portions being movable relative to the central portion. The lateral portions may be arranged for pivotal movement. At least one and preferably each lateral portion may comprise a base portion which at least partially overlaps with the central portion when the apron is in the contracted configuration (and optionally at least partially overlaps with the central portion when the apron is in the expanded configuration) . At least one and preferably each lateral portion may comprise a wall portion for retaining excavated material on the apron. At least one (and preferably both) of the wall portions may optionally be pivotally attached to an excavator structure to facilitate pivotal movement of the respective lateral portion.

A variable length member may be provided for moving one of the movable plates or movable lateral portions. The variable length member may be in the form of a piston. One end of the variable length member may be attached to the movable plate or movable lateral portion and the other end of the variable length member may be attached to the non-movable plate (or non-movable central portion) . Attachment of the ends of the variable length member may be pivotal. Varying of the length of the variable length member typically causes movement of the movable plate or lateral portion relative to the non-movable plate or central portion. The excavator vehicle of the second aspect of the present invention may comprise any of the features described above in relation to the excavator vehicle of the first aspect of the present invention.

In accordance with a third aspect of the present invention, there is provided an excavator vehicle kit comprising:

(i) an excavator vehicle main body;

(ii) an excavator arm for attachment to the excavator vehicle main body, the arm being attachable to an excavator attachment; and

(iii) an elongate beam for attachment to the excavator

main body, the elongate beam being operable to move an excavating attachment along the longitudinal axis of the beam.

The excavating vehicle kit of the third aspect of the present invention provides an adaptable machine which may operate with the excavator arm or the beam. The arm may typically be used for driving a heading into a chamber, and the beam may typically be used to excavate material which is out of reach of the excavating attachment attached to the arm.

Those skilled in the art will realise that in the excavator kit of the present invention neither the arm nor the elongate beam is necessarily provided with an excavating attachment, merely that the arm is attachable to an excavating attachment and that the beam is operable to move an excavating attachment in the described manner, if an attachment is fitted to the beam or arm.

The excavator vehicle kit may be provided with more than one excavating attachment, for example, one which is suitable for attachment to the arm and one which is suitable for attachment to the beam. The one which is suitable for attachment to the beam may comprise a T-shaped attachment, optionally comprising a central portion for attachment to the beam and cutting portions either side of the central portion. The excavator attachment suitable for attachment to the arm may comprise a cutter portion for cutting material from a substrate and a bucket portion for collecting excavated material.

The arm may have a first arm portion which may be pivotally attachable to the excavator main body, and a second arm portion pivotally attached to the first arm portion. The arm may further comprise a third arm portion pivotally attached to the second arm portion. The second arm portion may be

pivotally attachable to an excavating attachment. The third arm portion may be pivotally attachable to an excavating attachment .

The beam may be operable to move an excavating attachment along the length of the beam.

The excavator vehicle may comprise, or be connectable to, a power pack for powering the excavator vehicle thereby

rendering the vehicle operable.

The excavator vehicle kit of the third aspect of the present invention may comprise any of the features described above in relation to the excavator vehicle of the first aspect of the present invention.

In accordance with a fourth aspect of the present invention, there is provided an excavator vehicle for excavating

material, the excavator vehicle comprising, or being

connectable to, a power pack for powering the excavator vehicle thereby rendering the vehicle operable, the excavator vehicle comprising a seat for an operator of the excavator vehicle, movement of at least part of the seat in a pre-determined manner causing at least part of the excavator vehicle to be inoperable. It is occasionally necessary to leave the excavator vehicle in a hurry. The applicant has found that it is desirable to provide a mechanism to disable at least part of the excavator vehicle before leaving the vehicle, a process which may bring the leaving user into close proximity with parts of the excavator, the movement of which may be undesirable when the operator is in proximity.

Those skilled in the art will realise that movement of the at least part of the seat may well, of course, render the seat inoperable. The at least part of the excavator which is caused to be inoperable is not the seat.

Those skilled in the art should recognise that not all movements of the seat necessarily render the excavator vehicle (or part thereof) inoperable. For example, the seat (or part thereof) may be adjustable to suit the size of the user. For example, seat may be movable in a forwards/backwards direction and/or in an up/down direction to suit the size of the operator.

Said movement of the seat or part thereof in said predetermined manner may create an escape path for the operator in the event of an emergency.

The seat may comprise a seat back. The seat back may

optionally be moveable in said pre-determined manner to cause at least part of the excavator vehicle to be inoperable, for example, by folding the seat back forwards or backwards.

Alternatively, the seat back may be removable so as to cause at least part of the excavator vehicle to be inoperable. The seat may be associated with a vehicle main body. The power pack, if present, may be located remote from the vehicle main body.

The excavator may optionally be powered by a fluid, for example being hydraulically powered or being powered by liquid fuel, and therefore the power pack may comprise a means for providing fluid to the excavator vehicle. In this case, the excavator vehicle may comprise a valve, operable between first and second states, wherein in the first state a first flow path is established to permit f.luid to be transmitted to the vehicle (or part thereof) so that the vehicle (or part thereof) is operable, and in the second state there is no flow path to the excavator (or part thereof) so that the excavator (or part thereof) is inoperable. In this case, said pre- determined movement of the seat (or part thereof) causes the valve to be in the second state. The connection between the seat (or part thereof) and the valve may be provided by one or more of one or more cables, one or more rods or a cam. In the second state, a flow path may be established to a return fluid circuit so that pressure does not build-up in a hydraulic circuit.

The excavator may optionally be electrically powered, and therefore the power pack may comprise means for providing electrical energy to the excavator vehicle. In this case, the excavator vehicle may be provided with a switch for cutting power to the excavator vehicle (or part thereof) , said predetermined movement of the seat (or part thereof) causing the switch to be actuated.

Those skilled in the art will realise that causing the excavator (or part thereof) to be inoperable does not

necessarily mean that power is cut from the excavator (or part thereof) . For example, the pre-determined movement of the seat (or part thereof) could disengage part of the excavator from a driving mechanism so that the disengaged part no longer moves. For example, said pre-determined movement may disengage a conveyor from the driving mechanism by the use of a clutch which may be disengaged when the seat is moved.

The excavator vehicle may have a front and a rear, said predetermined movement of the seat (or part thereof) renders inoperable at least one component of the excavator vehicle which is located at least partly to the rear of the seat. In this connection, the excavator may optionally comprise a conveyor which may optionally extend to the rear of the seat. The pre-determined movement of the seat (or part thereof) may cause the conveyor to stop. This is particularly advantageous when the conveyor comprises an auger or screw conveyor since placement of feet into an operating auger conveyor would be bad.

The seat may be provided with a locking mechanism. The locking mechanism may be operable between a first state in which said movement of the seat (or part thereof) is resisted and a second state in which said movement of the seat (or part thereof) is not resisted. Alternatively, the locking mechanism may comprise a frangible locking portion. Such a locking portion may be broken on the application of a considerable force to the seat (or part thereof) .

When the seat is ready for use it may be considered to be in a deployed position. If the seat is in the deployed position, then the excavator (or part thereof) is operable. Returning the seat into the deployed position from the state in which the excavator (or part thereof) is inoperable may make the vehicle (or part thereof) operable once more (subject to the actuation of any other safety features as is discussed below) . The excavator may be provided with further safety features, for example, a dead man's switch should cause the excavator to be inoperable in the event that the dead man' s switch is released. However, such dead man's switches are not fool-proof and may fail, and therefore the present invention provides an additional safety feature to reduce the risk to the operator.

The excavator vehicle of the fourth aspect of the present invention may comprise any of the features described above in relation to the excavator vehicle of the first aspect of the present invention.

In accordance with a fifth aspect of the present invention there is provided an excavator vehicle comprising a conveyor for moving excavated material, the conveyor comprising a rotatable screw for moving excavated material, the screw being at least partially disposed within an enclosure, the enclosure being provided with an aperture for egress of excavated material, the enclosure being provided with a movable

aperture-defining portion for adjusting the size and/or the position of the aperture. The excavator of the fifth aspect of the present invention may be of particular benefit when the excavator is to be operated in a tilted chamber. The ability to adjust the position of the aperture enables the conveyor to deliver excavated material efficiently to a collection point. The enclosure is typically provided to retain the excavated material in close proximity to the screw so that the screw may move the excavated material.

The conveyor may be considered to have a longitudinal axis parallel to the screw axis. The aperture defining portion may be movable so as to vary the angular position of the aperture relative to the longitudinal axis of the conveyor. This may be of particular use when the excavator is working when on a tilt. For example, the movable aperture defining portion may comprise a rotatable sleeve provided with an aperture, the sleeve being rotatable so as to vary the angular position of the aperture relative to the longitudinal axis of the

conveyor. Alternatively or additionally, the moveable aperture defining portion may comprise one or more movable shutters, operable to define an aperture for the egress of excavated material, the shutters being moveable to vary the angular position of the aperture relative to the longitudinal axis of the conveyor. The one or more moveable shutters may also be movable to vary the size of the aperture.

The conveyor is typically elongate. The enclosure is typically in the form of a housing. The housing may be cylindrical, typically in the form of a right circular cylinder. The aperture for egress of excavated material is typically located at or near one end of the conveyor. The conveyor typically has a front associated with the front of the excavator vehicle and a rear associated with the rear of the excavator vehicle, the aperture for egress of excavated material being located closer to the rear of the conveyor than the front of the conveyor. The excavator vehicle typically comprises an excavator main body having a front and a rear. The conveyor typically extends past the rear of the excavator main body. This enables a receptacle or removing conveyor (not being the conveyor mentioned above) to be placed so as to receive excavated material from the conveyor of the excavator of the present invention. The conveyor of the excavator of the present invention may be movable so as to vary the angle of pitch of the conveyor.

The excavator vehicle of the fifth aspect of the present invention may comprise any of the features described above in relation to the excavator vehicle of the first aspect of the present invention.

In accordance with a sixth aspect of the present invention, there is provided an excavator vehicle having a first means for moving the excavator vehicle, the first means for moving the vehicle being associated with the bottom of the vehicle, and optionally a second means for moving the vehicle, said second means for moving the vehicle being associated with an upper part of the vehicle. The second means for moving the vehicle, if present, may advantageously engage with a roof or wall of a chamber. This may be of particular. use in the event that the chamber is laterally tilted (as sometimes happens for a narrow chamber) in which case the second means for moving the vehicle may be arranged to engage the wall of the chamber.

The excavator may comprise a third means for moving the vehicle, the third means for moving the vehicle being

associated with an upper part of the vehicle.

The excavator may be provided with a cab for the protection of the operator or a roof. The second means (and third means, if present) for moving the vehicle may optionally be attached to the cab or the roof.

The second means for moving the vehicle, if present, may be located to the left or right hand side of the excavator (as opposed to being located on a centre line of the excavator) .

If a third means for moving the vehicle is present, then the second means for moving the vehicle may be located to one or the left or right hand side of the vehicle and the third means for moving the vehicle may be located to the other of the left or right side of the vehicle. The second means (and third means, if present) for moving the vehicle typically comprises a surface for contacting the ground so as to enable movement of the vehicle. The second (and third means, if present) for moving the excavator may be arranged so that said surface is for contacting ground above the excavator or to the side of the excavator. In narrow chambers or in chambers which are tilted, it may be desirable for a wheel or track surface to contact a chamber wall, as opposed to a chamber ceiling. The excavator vehicle may comprise a fourth means for moving the vehicle, the fourth means being associated with the bottom of the vehicle. The first means (and fourth means, if present) for moving the vehicle typically comprises a surface for contacting the ground so as to enable movement of the vehicle. The first (and fourth means, if present) for moving the excavator may typically be arranged so that said surface is for contacting ground beneath the excavator. However, the first (and fourth, if present) means for moving the excavator may be arranged so that said surface is for contacting ground to the side of the excavator. The first and fourth means for moving the vehicle may each be configurable in a first

configuration for engaging ground beneath the excavator vehicle (such as a chamber floor) and a second configuration for engaging the ground to the side of the excavator (such as a chamber wall) . The first means is attachable in the first and second configurations. The fourth means is attachable in the first and second configurations. For the avoidance of doubt, it is hereby stated that the first and fourth means are releasably detachable in the first and second configurations. In operation, the first means may be attached in the first or second configuration, and then moved to the other of the first and second configuration. Likewise, in operation, the fourth means may be attached in the first or second configuration, and then moved to the other of the first and second configu ation .

It is typical for both of the first and the fourth means to be configured in the first configuration, or for one of the first and fourth means to be in the first configuration and the other of the first and fourth means to be in the second configuration. Whilst possible, it would be unusual for both the first and fourth means to be in the second configuration.

The first means, second means, third means (if present) and fourth means (if present) for moving the vehicle may comprise a caterpillar track, for example. The first means, second means, third means (if present) and fourth means (if present) for moving the vehicle may be individually selected from a ground-engaging track arrangement and a set of one or more ground-engaging wheels. The sixth aspect of the present invention therefore provides: an excavator vehicle having a first ground-engaging track arrangement or a first set of one or more ground-engaging wheels, the first ground-engaging track arrangement or the first set of one or more ground-engaging wheels being'

associated with the bottom of the vehicle, and optionally a second ground-engaging track arrangement or a second set of one or more ground-engaging wheels, said second ground- engaging track arrangement or a second set of one or more ground-engaging wheels being associated with an upper part of the vehicle.

The excavator vehicle of the sixth aspect of the present invention may comprise any of the features described above in relation to the excavator vehicle of the first aspect of the present invention. For example, the vehicle may comprise a single, single-width track arrangement for engaging ground beneath the vehicle.

In accordance with a seventh aspect of the present invention, there is provided an excavator attachment kit for an

excavator, the kit comprising:

(i) a first excavator attachment portion comprising a scoop,

(ii) a first cutter device of a first type for excavating rock or the like; and

(iii) a second cutter device of a second type for

excavating rock or the like; the first and second cutter devices being interchangeably mountabie to the first excavator attachment portion so as to form an excavator attachment comprising the first excavator attachment portion and a cutter device.

The scoop may be in the form of a bucket.

The first cutter device may optionally comprise a single rotary cutter of elongate configuration mountabie to the first excavator attachment portion so that the cutter device has a proximal end associated with the scoop and a distal end remote from the scoop.

The second cutter device may optionally comprise one or more rotary cutters. The second cutter device may comprise a T- shaped device.

The first excavator attachment portion may comprise a first configuration for mating with a corresponding configuration provided on the first and second cutter devices. For example, the first configuration may be in the form of a female configuration for receipt of a male configuration provided on the first and second cutter devices. Alternatively, the first configuration may be in the form of a. male configuration for insertion into a female configuration provided on the first and second cutter devices. The female configuration may be in the form of a recess. The male configuration may be in the form of a protrusion.

For the avoidance of doubt, the features below are applicable to the excavators of the first, second, third, fourth, fifth, sixth and ninth aspects of the present invention except where the teachings of the features below are incompatible with the statements made above in relation to the excavators of the present invention.

The excavator may comprise an excavator main body. If the excavator comprises an apron, then the apron may be located at or in proximity to the front of the main body. If the

excavator comprises a conveyor, then the conveyor may extend from the apron to the rear of the main body, the conveyor, in use, moving excavated material from the front to the rear of the main body.

The excavator may comprise an arm. The arm may be provided with an attachment for excavating material and/or moving said excavated material towards the apron.

It is preferred that the arm is mounted for rotational

movement. The arm may be rotatably attached to the excavator main body, attachment of the arm to the main body providing a first pivotal axis, the arm being rotatable in relation to the main body through an angle of at least 150 degrees about said first pivotal axis.

The arm may be attached to the main body at, or in proximity to, the front of the main body. This is a convenient

arrangement for excavating material in front of the main body. It is further preferred that the arm is rotatable in relation to the main body through an angle of at least 300 degrees (and more preferably through an angle of at least 350 degrees) about the first pivotal axis. Such a rotational motion allows the arm to act as a crane. It also assists in storage of the arm.

If the arm is rotatable through 180 degrees or less, it is preferred that the excavator is provided with one or more rams for rotating the arm about the first pivotal axis. If the arm is rotatable through more than 180 degrees, it is preferred that the excavator may be provided with a slew ring and motor for rotating the arm about the first pivotal axis.

It is preferred that the arm is articulated, with a first arm portion associated with the main body connected to a second arm portion by a joint. The second arm portion may be attached to an excavator attachment or may be attached to a third arm portion, in which case the third arm portion may be attached to an excavator attachment.

The excavator may be provided with a cab for protecting an operator.

The excavator main body may have a width of from 0.4 to 2m, optionally from 0.4 to 1.5m and further optionally from 0.5 to lm.

The excavator may typically be provided with, or connectable to, a power pack for providing power to the excavator.

The excavator may optionally be provided with one or more power transmission conduits for connection to a power pack. Such power transmission conduits may be electrical cables or may be conduits for the transmission of hydraulic fluid, for example . The excavator may be provided with a power transmission conduit receiving arrangement for connection to the one or more power transmission conduits. For example, the excavator may be provided with the female or male parts of an electrical connection, the corresponding male or female part being provided on the one or more power transmission conduits.

Alternatively, the excavator may be provided with the male or female parts of a hydraulic fluid connection, the

corresponding male or female part being provided on the one or more power transmission conduits.

The excavator may be provided with means for moving the excavator, such as caterpillar track arrangements or ground- contacting wheels. An excavator may typically be provided with a first means for moving the vehicle, said first means being associated with the left hand side of the vehicle, and a second means for moving the vehicle, said second means being associated with the right hand side of the vehicle. For example, the excavator vehicle may be provided with a left side caterpillar track and a right side caterpillar track. The first means and second means for moving the vehicle typically each comprise a surface for contacting the ground so as to enable movement of the vehicle. The first and second means for moving the excavator may each be independently arranged so that said surface may contact ground beneath the excavator or to the side of the excavator. In narrow chambers or in

chambers which are tilted, it may be desirable for a wheel or track surface to contact a chamber wall, as opposed to a chamber floor.

The excavator may comprise one or more laterally extendable jacks. Such jacks typically extend out of the side of the excavator to engage a wall of the chamber. Such engagement may be used to inhibit movement of the excavator during the excavation process. Furthermore, the jacks may be used to move the excavator laterally, which can be beneficial, for example, to move the excavator around an obstruction. The excavator may typically comprise at least one pair of laterally extendable jacks, the jacks in each pair being associated with different lateral sides of the excavator and being extendable in

different directions (typically being extendable in opposite directions) . The excavator may comprise two of said pairs of jacks, a first pair being associated with the front of the excavator and a second pair being associated with the rear of the excavator. The first pair may be located at or near the front of the excavator main body. The second pair may be located at or near the rear of the excavator main body.

The excavator may comprise one or more lateral bumpers or buffers. The bumpers of buffers may reduce the likelihood of the excavator being damaged. The bumpers or buffers may be located on the side of the excavator main body. Typically, the excavator may comprise one or more left-hand lateral bumpers or buffers and one of more right-hand lateral buffers or bumpers. At least one lateral bumper or buffer may comprise a rotatable wheel or roller. At least one lateral bumper or buffer may comprise a plurality of wheels or rollers.

Alternatively or additionally, at least one or more lateral bumper or buffer may comprise an elongate member extending in a direction from the front to the rear of the vehicle. The elongate member may extend from the front of the main body to the rear of the main body.

In the statements above, the main body may be a prime mover for moving the excavator. The excavator main body does not include any of the apron, the conveyor or arm.

In accordance with an eighth aspect of the present invention there is provided a method of operating an excavator vehicle comprising a screw conveyor for moving excavated material, the method comprising operating the screw conveyor when the excavator vehicle is tilted laterally from the vertical by an angle of at least 5°. It has been found that screw conveyors perform well compared to other conveyors when the excavator is tilted sideways.

"Laterally" indicates that the excavator is tilted to the side, for example the left or right (as opposed to forwards or backwards) . The vertical may be readily determined by a person skilled in the art, for example, by using a plumb line.

The excavator vehicle may be tilted laterally by at least 10°, optionally by at least 20°, optionally by at least 30°, optionally by up to 90°, optionally by 70° or less and

optionally by 50° or less. The conveyor typically extends in rearwardly from near the front of the conveyor. The excavator vehicle used in the method of the eighth aspect of the present invention may comprise those features described above in relation to the excavator vehicles of the first, second, fourth, fifth and sixth aspects of the present invention. Indeed, the excavator vehicle used in the method of the eighth aspect of the present invention may be the excavator vehicle of the first, second, fourth, fifth, sixth and ninth aspects of the present

invention . In accordance with a ninth aspect of the present invention, there is provided an excavator vehicle comprising a single, single-width track arrangement for engaging ground beneath the excavator vehicle, the single-width track arrangement being operable to move the excavator vehicle. The single-width track arrangement facilitates the production of a very narrow vehicle that may be used in very confined spaces. Furthermore, it has been found that using a dual-width track arrangement in which there are two tracks side-by-side has caused unexpected problems. For example, spoil may accumulate between the two tracks and cause jamming of one or both of the two tracks, which may cause the machine to "crab" sideways and/or for damage to be caused to the gearbox. For the avoidance of doubt, the excavator vehicle has only one single-width track arrangement for engaging ground beneath the excavator vehicle to move the vehicle and no other vehicle- moving track arrangement for engaging with the ground beneath the vehicle. As mentioned below, the excavator vehicle may be provided with powered tracks or other ground-engaging means (such as powered wheels) for engaging ground to the sides of the excavator vehicle and/or above the excavator vehicle.

The single-width track arrangement typically only has one operating position i.e. it cannot be moved to a different operating position, nor can it be moved to a different orientation so that it can engage with ground to the side of the excavator, for example. The position of the single-width track arrangement is therefore fixed in one operating

position. Those skilled in the art will realise that the track arrangement may be removed for maintenance or the like, and that parts of the track arrangement will move.

The single-width track arrangement may comprise a single track for engaging ground beneath the vehicle. Alternatively, the single-width track arrangement may comprise a plurality of tracks, mutually spaced along the length of the single-width track arrangement.

The single width track arrangement may optionally be less than lm wide . The excavator vehicle may comprise a vehicle main body located beneath which the single-width track arrangement is located. The word "beneath" is indicative of the position of the single-width track arrangement when the excavator vehicle is in an upright orientation. The single-width track arrangement may optionally extend along the length of the vehicle main body.

The single-width track arrangement may optionally be located laterally centrally in relation to vehicle main body.

The excavator vehicle may comprise a motor for powering the track (s) of the single-width track arrangement, and optionally a gear box associated with said motor and said track (s) of the single-width track arrangement. The gear box and motor are optionally provided as part of a module which is removably attached. This facilitates the quick removal of the module to service and fix any problems in said gear box or motor. The module may be removably attached to a chassis unit comprising rollers for guiding the track. The module may be attached to the chassis unit using bolts and the like which facilitate removal of the module. The module may be located at or near one end of the single-width track arrangement. The module may be located towards or at the rear of the vehicle. This facilitates relatively easy access to the module. The module may be, in normal use, located within a space defined by a track of the single-width track arrangement.

The single-width track arrangement engages ground beneath the excavator vehicle. The excavator vehicle may optionally be provided with one or more powered tracks (or other ground- engaging means, such as wheels) for engaging ground to the side of the excavator, or above the excavator. Optionally, the excavator vehicle may be provided with one or more of: a powered track (or other ground-engaging means) for engaging ground to one lateral side of the excavator (say, the left), a powered track (or other ground-engaging means) for engaging ground to another lateral side of the excavator (say, the right), and a powered track (or other ground-engaging means) for engaging ground above the excavator. A powered track (or other ground-engaging means) for engaging ground to a lateral side of the excavator vehicle may be attachable to the

excavator main body in a plurality of positions. For example, the powered track (or other ground-engaging means) may be attachable to the excavator main body in a first position and in a second position, the first position being above the second position when the excavator is in an upright

orientation. Additionally or alternatively, the powered track (or other ground-engaging means) may be attachable to the excavator main body in a forward position and an aft position.

The excavator vehicle may optionally be provided with one of more ground-contacting supports, such as one or more skids or rollers. Such supports may contact the ground and provide support to the excavator vehicle, but typically do not assist in the routine forwards and backwards movement of the

excavator vehicle. One or more support may be provided for contacting ground beneath the excavator vehicle, but to one lateral side of the vehicle. The vehicle may be provided with one or more supports for contacting ground beneath, but to one lateral side of, the vehicle and one or more supports for contacting ground beneath, and to another lateral side of, the vehicle. Therefore, the vehicle may be provided with a support which contacts the floor of a chamber to the left of the vehicle main body, and a support which contacts the floor of the chamber to the right of the vehicle main body. Such an arrangement may help prevent the excavator from tipping over. One or more support may be provided for contacting ground to one lateral side of the vehicle and one or more supports may be provided for contacting ground to another lateral side of the vehicle.

One or more of the ground contacting supports may be

retractable or removably attachable to a ground-contacting support mount. Said mount may optionally be removably attached to the vehicle main body. In very confined environments, such as very narrow seams, there will be no room for said supports.

One or more ground-contacting support mounts may be arranged to receive a lifting arrangement (such as a jack or ram) . The lifting arrangement may be interchangeable with a ground- contacting support. The support (such as a skid or rollers) would be removed and replaced by the lifting arrangement. Such a lifting arrangement may be used to support the excavator vehicle, should any work need to be performed on said vehicle. Alternatively or additionally, the lifting arrangement may be used to free-up the vehicle, should it become stuck or jammed, as may happen occasionally in the environments in which the excavator vehicle typically works.

The excavator vehicle may be provided with one or more

laterally-extensible rams. The one or more rams may be

operable to contact a wall to the side of the excavator vehicle. The rams may be used to free-up the vehicle if it has become stuck or jammed. A first lateral side of the excavator vehicle may be provided with one or more rams and a second lateral side of the excavator vehicle may be provided with one or more rams .

The excavator vehicle of the ninth aspect of the present invention may comprise those features described above in relation to the excavator vehicle of the first aspect of the present invention, unless the presence of those features is incompatible with the excavator vehicle of the ninth aspect of the present invention. For example, whilst the excavator vehicle of the ninth aspect of the present invention may have powered tracks for engaging walls to the side of the vehicle, the excavator vehicle of the ninth aspect of the present invention can only have one single-width track arrangement for engaging ground below the vehicle. In particular, the

excavator of the ninth aspect of the present invention may optionally comprise an excavator arm, cutting attachment and apron, as described above in relation to the first aspect of the present invention.

The invention will now be described by way of example only with reference to the following figures of which:

Figure 1A is a plan view of an example of an excavator in accordance with the first, second, fourth and fifth aspects of the present invention;

Figure IB is a side view of the excavator of Fig. 1A;

Figure 1C is. an end-on front view of the excavator of Fig. 1A;

Figure ID is an end-on rear view of the excavator of Fig. 1A;

Figure 2A is a plan view of a further example of an excavator in accordance with the first, second, fourth, fifth and sixth aspects of the present invention;

Figure 2B is a side view of the excavator of Fig. 2A;

Figure 2C is an end-on front view of the excavator of Fig. 2A;

Figure 2D is an end-on rear view of the excavator of Fig. 2A; Figure 3A is a plan view of a further example of an excavator in accordance with the first, second, fourth, fifth and sixth aspects of the present invention;

Figure 3B is a side view of the excavator of Fig. 3A; Figure 3C is an end-on front view of the excavator of Fig. 3A;

Figure 3D is an end-on rear view of the excavator of Fig. 3A;

Figure 4 is a rear perspective view of an example of part of an excavator in accordance with the fifth aspect of the present invention;

Figure 5 is a perspective view from above of part of the excavator of Figure 4;

Figure 6 is a perspective view of an example of a beam-mounted cutter for use in an excavator kit in accordance with the third aspect of the present invention;

Figure 7 is a perspective view of an example of a cutter for use in an excavator attachment kit in accordance with the seventh aspect of the present invention;

Figures 8a-8e are end views of an example of an excavator, with ground-engaging tracks in different orientations, ; and

Figure 9 is a rear view of an excavator being used in an example of a method in accordance with the eighth aspect of the present invention;

Figure 10 is a perspective view of an example of an excavator in accordance with the second, fifth, sixth and ninth aspects of the present invention;

Figure 11 is an exploded view of the single-width track arrangement of the excavator of Fig. 10;

Figure 12A is a schematic front-on view of the excavator of Fig. 10 showing two lateral supports attached and a powered track provided for engaging ground to a lateral side of the vehicle; Figure 12B is a schematic front-on view of the excavator if Fig. 12A, but with the lateral supports removed, and with a powered track provided for engaging ground above the vehicle (such as the ceiling of a chamber) ; and Figure 12C is a schematic front-on view of the excavator if Fig. 12A, but with the lateral supports removed, and with a powered track provided for engaging ground to a different lateral of the vehicle.

A first example of an excavator in accordance with the present invention is shown in Figures 1A-D. The excavator vehicle is denoted generally by reference numeral 1, and is generally designed for use in narrow chambers. The excavator 1 comprises a frame 2 (having right hand 2a and left hand 2b frame parts) , to which is mounted right hand 3a and left hand 3b

caterpillars. The caterpillars 3a, 3b comprise ground- contacting tracks 4a, 4b which are driven by a powered, toothed wheel (only one of which is shown as reference numeral 5) as is well-known to those skilled in the art. The excavator 1 is provided with an arm 10, which is attached for pivotal movement about axis B. The arm 10 comprises a lower portion

10a pivotally attached at one end at pivot point 11. The lower portion 10a is pivotally attached at point 13 to upper arm portion 10b. Upper arm portion 10b is pivotally attached to an excavator attachment 14 at pivot point 12. The excavator 1 further comprises a conveyor 6 which comprises a screw 8 disposed within a housing 7. The screw 8 is arranged so that one end of the screw 8 receives excavated material from the apron 15. Operation of the vehicle of Figures 1A-D will now be described . Excavator attachment 14 comprises a bucket portion 14A for collecting excavated material and a cutter device 14B for cutting material from a substrate. The cutter device 14B is a rotary cutter and has a cutting head of a generally hemispherical shape. The cutting head is provided with a plurality of cutting teeth. In use, the cutting head rotates, providing a cutting action when the cutter head is urged into contact with a substrate. In use, the operator operates the attachment by causing the attachment 14 to rotate about pivot point 12 so that the cutter device 14B is presented to a substrate to be cut. The operator then urges the head of cutter device 14B into contact with the substrate as is well-known to those skilled in the art. The operator moves the cutter head 14B as is desired in order to cut the substrate. Once material has been excavated, the operator uses the bucket portion 14A of the attachment 14 to move excavated material onto apron 15. Apron 15 is arranged to receive excavated material. The apron 15 comprises a central portion 20 and right 21 and left 22 hand apron portions. Each of the right 21 and left 22 apron portions comprises floor parts 17a, 17b and walls 16a, 16b. The right hand and left hand apron portions are movable relative to the central apron portion, thereby providing an expandable apron. Floor parts 17a, 17b overlap with the central portion 20 of the apron. Movement of the right hand and left hand apron portions causes the area of the apron to increase or decrease, depending on the direction of movement. The walls 16a, 16b help retain excavated material on the apron. The left hand and right hand apron portions are pivotally mounted. The ability to increase the size of the apron is desirable when it is difficult to manoeuvre the vehicle in order to reposition the apron to collect more excavated material. Bucket portion 14A is used to move excavated material up the apron 15 to the conveyor 6. The conveyor 6 comprises a rotatable screw 8 disposed within a generally cylindrical housing 7. Rotation of the screw 8 moves excavated material along the conveyor 6 in the same manner as an Archimedean screw. The housing 7 keeps the excavated material in close proximity to the screw 8. The pitch angle of the conveyor may be altered as desired using piston 9. Material leaves the conveyor 6 via aperture A. Aperture A is provided in a rotatable portion 24 of the housing 7. The rotatable portion 24 is rotatable about the longitudinal axis of the conveyor, and therefore the angle of the aperture relative to the longitudinal axis of the conveyor may be altered. This is desirable should the excavator have to be used in a laterally- sloping chamber.

Material which leaves aperture A is collected by an additional conveyor (not shown) positioned beneath aperture A.

The excavator 1 of the present invention will typically be used in narrow chambers. In the event of an emergency, it may be desirable for the operator 0 to leave the vehicle 1. There will not be an escape route forward of the vehicle, and there is unlikely to be escape routes to the side of the vehicle. Therefore, the only possible escape route will be to the rear of the vehicle. Bearing this in mind, the excavator seat 23 may inhibit the ease with which an operator could exit the vehicle in the event of an emergency. The back portion 23A of the seat 23 is therefore movable so that it does not inhibit the operator's egress from the vehicle. The back portion 23A is pivotally mounted at one end (the end remote from the top of the seat back) so that the seat back may be rotated rearwardly so that the back portion 23A lies flat and

therefore provides less of an obstruction to the operator. The seat back 23A may, of course, be arranged so that it may be rotated forwards so that the pack portion 23A lies flat.

Rotation of the seat back 23A causes rotation of a cam (not shown) which actuates a valve (not shown) which disables the excavator 1 as will now be described.

The excavator 1 is hydraulically powered. The excavator 1 is connectable to a remotely-located power pack (not shown) which provides high-pressure fluid for the operation of the

excavator 1. Rotation of the seat back 23A to the flat position causes rotation of the cam which actuates a valve. In the unactuated state, the valve permits hydraulic fluid to flow to those powered components of the excavator (including, but not limited to the pistons for moving the arm 10, the conveyor 6, the piston 9 for moving the conveyor 6 and the drive wheel 5 for driving the right hand 3a and left hand 3b caterpillars) . In the actuated state, the valve shuts-off supply of hydraulic fluid to those powered components of the excavator 1. In this state, the valve diverts fluid to a return circuit (not shown) which returns fluid to the power pack. The diversion of fluid to the return circuit prevents the build-up of pressure that may occur if the valve was merely arranged to inhibit flow to fluid to the powered components.

In Figures 1A-1D, the right hand 3a and left hand 3b

caterpillars are shown outside the frame 2. The caterpillars 3a, 3b may be located inside the frame as will now be

described with reference to Figures 2A-2D. A further example of an excavator in accordance with the present invention is shown in Figures 2A-2D. The excavator is generally denoted by reference numeral 101. Excavator 101 has many technical features in common with excavator of Figures 1A-1D, and those features in common are labelled using the same reference numerals which are used in Figures 1A-1D. Like the excavator of Figures 1A-1D, the excavator of Figures 2A-2D comprises left hand 3b and right hand 3a caterpillars. However, in excavator 101 the caterpillars 3a, 3b are located internally of the frame 2. The configuration shown in Figures 2A-2D is especially preferred for working in narrow chambers. The excavator 101 of Figures 2A-2D has several features which are not present in the excavator 1 of Figures 1A-1D. The excavator

101 comprises a cab 102 which protects the operator 0. The cab

102 also provides an attachment platform for wheels 103a, 103b. The two wheels 103a, 103b are mounted on the left hand side of the cab 102. The wheels 103a, 103b are powered and may be used to move the excavator 101 by engaging a wall. The wheels may engage a wall, for example, when the excavator 101 is operating in a chamber which tilts the excavator 101 to the left.

In Figures 1A-1D, the right hand 3a and left hand 3b

caterpillars are shown outside the frame 2. The caterpillars 3a, 3b may be located inside the frame as will now be

described with reference to Figures 3A-3D. A further example of an excavator in accordance with the present invention is shown in Figures 3A-3D. The excavator is generally denoted by reference numeral 201. Excavator 201 has many technical features in common with excavators of Figures 1A-1D and

Figures 2A-2D, and those features in common are labelled using the same reference numerals which are used in Figures 1A-1D and Figures 2A-2D. Like the excavator of Figures 1A-1D, the excavator of Figures 3A-3D comprises left hand 3b and right hand 3a caterpillars. However, in excavator 201 the

caterpillars 3a, 3b are located internally of the frame 2. The configuration shown in Figures 3A-3D is especially preferred for working in narrow chambers. The cab 102 provides an attachment platform for a caterpillar track 204 which is driven by a powered axle 205. The

caterpillar track 204 is mounted on the left hand side of the cab 102. The powered caterpillar track 204 may be used to move the excavator 201 by engaging a wall. The track may engage a wall, for example, when the excavator 201 is operating in a chamber which tilts the excavator 201 to the left. The excavator 201 is provided right side 210 and left side 211 skids. The skids 210, 211 comprise elongate metal members which are fixed to the right hand 2a and left hand 2b frame parts. The skids act like bumpers or buffers to help keep the excavator upright and to help inhibit damage to parts of the excavator 201. The excavator 201 is also provided with two laterally-extendable rear jacks 206, 207 and two laterally- extendable front jacks 208, 209. The jacks have two prime uses. The first is to engage the side walls of the chamber to inhibit unwanted movement of the excavator which may occur, for example, during the excavation process. The second use is to move the excavator laterally to avoid obstructions. ^>

An alternative expandable apron will now be described with reference to Figures 4 and 5. The apron is denoted generally by reference numeral 1001. The apron 1001 comprises a central portion 1002 and two side portions 1003, 1004. The side portions help retain excavated material on the apron 1001. The side portions 1003, 1004 are pivotally attached. Three pivotal attachment points 1012, 1013, 1014 are shown in Figure 4. Side portions 1003, 1004 are attached to rear plates 1003a, 1004a which are attached to one end of pistons 1005, 1006

respectively at points 1008, 1010. The other end of each piston 1005, 1006 is attached to backplate 1020 at points 1007, 1009. Actuation of pistons 1005, 1006 causes the pistons to change length which causes pivotal movement of apron side portions 1003, 1004. This causes the apron to expand or contract, depending on whether the piston is lengthening or shortening . Apron side portions 1003, 1004 extend to the side of aperture 1121. Backplate 1020 is to the rear of aperture 1121.

Excavated material passes through aperture 1121 onto screw 8.

The speed of rotation of the screw 8 is variable. This allows the user to control the rate of movement of excavated material through the screw.

Figures 8a-8e show an example of an excavator according to the present invention. The excavator is generally denoted by reference numeral 2000. The excavator 2000 comprises an excavator body 2001, two lower caterpillar tracks 2002, 2003 and an upper caterpillar track 2004. Caterpillar tracks 2002, 2003 are releasably attached to the excavator body 2001. In Figure 8a, the caterpillar tracks 2002, 2003 are attached in a narrow configuration. Furthermore, the caterpillar tracks 2002, 2003 are arranged to contact ground beneath the

excavator 2000. The upper caterpillar track 2004 is attached on the left hand side of the excavator 2000. The upper

caterpillar track 2004 is releasably attached so that it may be moved from the left side to the right side, as is shown in Figure 8b. Each of the lower caterpillar tracks 2002, 2003 is attachable in one of two configurations. In one configuration, the lower caterpillar track is arranged for engaging the ground beneath the excavator, and in another configuration the lower caterpillar track is arranged for engaging the ground to the side of the excavator. For example, in Figure 8c,

caterpillar track 2002 is arranged to engage the ground to the side of the excavator vehicle, whilst caterpillar track 2003 is arranged to engage the ground beneath the excavator

vehicle. In Figure 8c, the upper caterpillar track 2004 is located on the left hand side of the vehicle. In Figure 8d, caterpillar track 2003 is arranged to engage the ground to the side of the excavator vehicle, whilst caterpillar track 2002 is arranged to engage the ground beneath the excavator vehicle. In Figure 8d, the upper caterpillar track 2004 is located on the right hand side of the vehicle. The arrangement of Figure 8c may be useful when the chamber is on a tilt to the left. Likewise, the arrangement of Figure 8d may be useful when the chamber is on a tilt to the right.

Figure 8e shows another alternative arrangement of the

excavator. In Figure 8e, the lower caterpillar tracks 2002, 2003 are attached in a wide configuration, and the upper caterpillar track has been removed . Figure 9 shows an excavator vehicle used in an example of a method in accordance with the eighth aspect of the present invention. The excavator vehicle is denoted generally by reference numeral 1, is shown from the rear and is essentially the same as the excavator vehicle described above in relation to Figures 1A-1D. The excavator vehicle 1 comprises a screw conveyor 6 for moving excavated material, left hand caterpillar tracks 3b and right hand caterpillar tracks 3a. The screw conveyor 6 extends from near the front of the excavator vehicle 1 to the rear. The

excavator vehicle 1 is located in a chamber C to be excavated. The walls of chamber C have been omitted for clarity. The excavator vehicle 1 is tiled at an angle a to the vertical shown as arrow V. The vertical may be determined using a plumb line, for example. The angle a is, in this case, about 15°. The conveyor 6 is capable of moving excavated material to the rear of the excavator vehicle 1 without significant amounts of material being lost from the conveyor or without significant amounts of material becoming stuck in, on or around the conveyor. Other conveyors (such as chain or belt conveyors) do not work well when the excavator is tilted.

The angle a need not be 15°, but may typically be from about 5° to about 90°. If the angle is high, then a different arrangement of caterpillar tracks may be used, such as those described above in relation to the excavator vehicle of

Figures 8a and 8c. Those skilled in the art will realise that the excavator of Figures 1A-1D and Figure 9 may operate when the lateral tilt angle from the vertical is less than 5°. When the tilt angle is less than 5°, other conveyors (such as belt and chain conveyors) work well, and therefore the screw conveyor does not have such an advantage over other conveyors.

Figure 10 is a perspective view of an example of an excavator in accordance with the second, fifth, sixth and ninth aspects of the present invention. The excavator is denoted generally by reference numeral 3000, and comprises a single, single- width track arrangement 3002 for contacting the floor and moving the excavator vehicle 3000. The single-width track arrangement 3002 is located beneath the excavator main body 3001. The excavator vehicle 3000 comprises many of the

features of the excavator vehicles described above in relation to Figures 1-9. For example, the excavator vehicle 3000 comprises an arm 10 and an excavating attachment 14 comprising a bucket portion 14a and a cutter head 14b, which operate as described above to excavate and move excavated material to an apron 1001 located at the front of the vehicle main body 3001. The apron 1001 essentially operates as described above in relation to Figs. 4 and 5, and is arranged so that excavated material can be moved from the apron 1001 to an conveyor 6 comprising a screw or auger (not shown) . The conveyor 6 operates to move excavated material to the rear of the

excavator vehicle 3000, and is arranged to deposit excavated material to a receptacle (not shown) or a conveyor (not shown) for transferring excavated material away from the vehicle. The excavator vehicle 3000 is hydraulically powered as described above in relation to the excavator vehicle of Figs. 1A-1D. The excavator vehicle 3000 comprises only a single, single- width track arrangement for contacting ground beneath the excavator vehicle 3000 (no other means for contacting ground beneath the vehicle and propelling the vehicle in a generally forwards and backwards manner is provided) ; this facilitates the production of a very narrow excavator vehicle 3000 which can be used in extremely confined spaces. The environments in which the excavator vehicle may be used may be extremely confined and the excavator may sometimes become stuck or may tip laterally, and cannot be moved using the single-width track arrangement 3002. To assist in the freeing-up of the excavator vehicle 3000, it has been found to be advantageous to provide rams 3007, 3008 on each lateral side of the

vehicle. These rams are extensible so as to engage with the walls of a chamber and exert a lateral force on the vehicle, thereby freeing it if it has become jammed, or righting it if the vehicle has tipped laterally. Additional rams (not shown) are provided on the lateral side of the excavator vehicle 3000 which is not visible in Fig. 10. The single-width track arrangement 3002 comprises a single continuous track

comprising a series of plates 3003 linked together to form a continuous track as is well known to those skilled in the art.

Excavator 3000 may be provided with lateral supporting skids as shown schematically in Fig. 12a. The supports 3101, 3102 are provided one to each side of the vehicle main body 3000. Each support 3101, 3102 is releasably attached to the vehicle main body (for example, at position 3008 or 3009 in Fig. 10 and at corresponding positions on the other lateral side of the vehicle not shown in Fig. 10) so that the supports can be removed when not needed and/or when the environment is too confined for the supports to be used. Each support 3101, 3012 comprises a support mount 3103, 3104, each of which is

provided with a ground-contacting skid 3105, 3106 which is releasably attached to the respective support mount. The ground-contacting skids may be interchanged with a jack (not shown) or the like. The jacks may be used to support the weight of the excavator vehicle so that servicing or other work may be performed in safety. Alternatively or

additionally, the jacks may be used to free-up the vehicle, should it become stuck or should it tip over.

The excavator vehicle is also provided with a ground-engaging powered track 3050. This track is attachable to the excavator 3000 in a variety of positions as shown in Figs. 12a, b, c so that it can engage with a chamber wall or the ceiling, and assist in the movement of the vehicle 3000.

Figure 11 is an exploded view of the single-width track arrangement 3002. The track itself has been omitted for the purpose of clarity. The single-width track arrangement 3002 comprises a chassis portion 3004 located forward of a module 3005 comprising a motor 3010 and a gear box 3011. The module 3005 is provided with flanges 3015 for releasable attachment to corresponding flanges 3016 provided on the chassis portion 3004. The releasable attachment of the module 3005 has been found to be advantageous in helping to improve access to the motor and gear box. The module 3005 comprises driving gears 3011a, 3011b for engaging with, and driving, the track. The single-width track arrangement further comprises pinch guards 3013, 3014 located to respective sides of the central portion 3012 of the chassis portion 3004. A plurality of upper rollers 3018a-c and lower rollers 3017a-e are provided to guide the track, as will be well-known to those skilled in the art. A tensioning arrangement 3019 is provided to adjust the tension in the track. The tensioning arrangement 3019 comprises end rollers 2023a, b rotatably mounted on axle 3020. The rollers, in use, engage with the track. Axle 3020 is, in use, located in slot 3022 and axle 3020 may be moved in a longitudinal direction against the tension applied by spring 3021. The longitudinal position of the axle 3020 determines the tension in the track. The excavators of Figures 1A-1D, 2A-2D, 3A-3D, 10, 11 and 12A- C comprise an arm and an apron. The arm and apron may be replaced by a beam beam-mounted cutter, such as that shown in Figure 6. The beam 501 is attached to the excavator frame 2 at attachment points 502, 503. A cutter attachment 504 is attached to the beam 501 and is movable along the length of the beam 501. The cutter attachment 504 is in this case, a T- shaped attachment with a laterally-extending rotary cutter 505. The rotary cutter 505 comprises a plurality of cutting teeth (not shown) . The beam-mounted cutter is typically used to excavate material which is not accessible using the arm. The interchangeability of the arm and beam-mounted cutter is therefore of great benefit.

The excavators of Figures 1A-1D, 2A-2D, 3A-3D, 10, 11 and 12A- C comprise excavator attachment 14. Excavator attachment 14 comprises a bucket portion 14a and a cutter device 14b. Figure 7 shows an alternative excavator attachment 601 comprising bucket portion 14a and a different cutter device 606. Cutter device 606 is essentially T-shaped and comprises a laterally- extending elongate, rotary cutter 610. The rotary cutter 610 is provided with a plurality of cutting teeth, one of which

611 is labelled. The cutter device 606 is interchangeable with cutter device 14b. Each cutter device 14b, 606 comprises a hub 14c, 608. The hub 14c, 608 is provided with a motor for powering the cutter device. Each cutter device 14b, 606 is provided with a male member 609 which is inserted into a receiving space 607 (shown in dotted lines) provided in the bucket portion 14a. The excavator above is described as having a portion of the housing of the auger conveyor which is rotatable so that the angle of the aperture defined in the housing can be varied. This need not be the case. For example, the orientation of the housing (and therefore the aperture) may be fixed.

Alternatively, the size and orientation of the aperture may be altered by providing one or more shutters which may be used to close or open a relatively large aperture, thereby defining the size and shape of the aperture through which excavated material may pass.

Where, in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable

equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present

invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent

claims .