The present invention relates to motors and is particularly applicable to motors used in the mining industry as part of an apparatus for excavating tunnels . Background of the Invention

In a typical micro tunnelling operation, a tunnel boring machine has wall clamps which are engaged against the wall of a mine shaft by hydraulic rams . These clamps rest in front of the tunnel casing which is composed of rings of segmented reinforced segment laid in position. Axial rams then, push against the casing to provide a thrust force for the cutting head of the boring machine. The walls clamps provide torque resistance for the cutting head.

Cuttings are typically placed on a conveyor belt for transportation to the surface , although some machines produce a slurry for pumping to the surface.

Micro tunnelling machines are generally designated as tunnel boring machines of less than 2 metres in diameter .

A typical micro tunnelling apparatus incorporates a motor which drives a central shaft which is connected to the cutting head. The motor is controlled to spin the shaft which spins the cutting head in a typical excavating operation .

Current motor designs for micro tunnelling apparatuses do not allow for flexibility of the operation of the cutting head. Furthermore the overall design of micro tunnellers incorporating conventional motors limits excavating operations to essentially straight tunnels or tunnels with a long radius of curvature.

The present invention provides an alternative type of motor for driving a shaft in an excavating device and in general covers an apparatus for driving a shaft. Summary of the Invention

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According to one aspect of the present invention there is provided an apparatus for driving a shaft in an excavating device comprising a plurality of linear actuating devices driven by fluid, a wobble plate device coupled to a shaft and a coupling means coupling the linear actuator devices to the wobble plate device, whereby controlled operation of the linear actuator devices results in linear reciprocating motion of the linear actuating devices being converted to rotational motion of the shaft through the coupling means and wobble plate device .

It is preferred that the linear actuating devices include any devices which are able to increase and decrease in axial length . Thus hydraulic and pneumatic rams are included along with cylinders with piston rods or equivalent devices .

It is preferred that the linear actuating devices each comprise a cylinder with an actuable rod such as a piston rod. Preferably each piston rod is driven by water.

The apparatus may include a controller which controls movement of the piston rods .

The apparatus preferably includes a plurality of valves which are controlled by the controller to move the piston rods.

Each cylinder may have an associated valve and a venting port.

Each valve may be controlled by a solenoid of the control means . The coupling means may comprise couplings between ends of each rod and ends of a coupling device .

The coupling device may comprise a plurality of radially extending coupling members .

Preferably each coupling member is coupled to one rod.

Each coupling member may have an outer end with a bearing surface which allows a degree of linear and

rotational movement relative to the rod with which it is coupled.

Each coupling member may form a universal joint with one of the rods . Preferably each bearing surface is substantially spherical in shape .

The degree of movement between the coupling members and each rod may be dependent upon physical dimensions of components of the apparatus . The degree of movement between the coupling members and each rod is preferably dependent upon the degree of movement permissible for the wobble plate device .

The coupling means may include a bearing means which couples the coupling device with the wobble plate device .

Preferably the bearing means comprises an inner and outer race .

The coupling device may be seated inside the bearing means.

Preferably the bearing means is coupled with the wobble plate device .

The outer race may be located in a seating recess of the wobble plate device . Preferably the coupling device is seated in a recess of the inner race.

The wobble plate may be coupled to a spline section of the shaft.

Preferably the apparatus comprises a plurality of chambers including an oil chamber and water chamber.

Preferably the oil chamber houses at least part of the coupling means and/or wobble plate and/or cylinder rods .

The cylinders may be located in a separate chamber from the coupling means.

The wobble plate device may comprise a wobble plate with a lower recess for part of the bearing means.

Preferably movement of the bearing means within the lower recess rotates the wobble plate .

The wobble plate preferably has a frusto cylindrical shape . The bearing means preferably comprises a stepped cylindrical body having a first stepped region of a first diameter and a second stepped region of a second diameter less than the first diameter.

It is preferred that the first stepped region is configured to be seated in the recess of the wobble plate.

Preferably the stepped region is coupled to the plurality of radially extending coupling members .

Preferably the wobble plate device is coupled to a splined section of the shaft. Preferably the controller actuates the linear actuators in a predetermined sequence by controlling each associated valve .

Preferably when each valve is opened the linear actuator is actuated. Preferably each piston extends in length from its cylinder when its associated valve is opened.

Preferably half of the valves are open while the other half are closed in a normal operational mode of the motor . Preferably the apparatus comprises eight linear actuators each with an associated valve.

Each valve is preferably opened for the same amount of time .

Preferably each valve remains open until a predetermined number of other valves have opened.

According to one embodiment torque applied to the shaft by the motor is controlled by varying the time each valve is opened/closed.

It is preferred that each valve is opened for the same amount of time as other valves .

According to one embodiment each of the pistons are controlled by opening and closing associated valves to

produce a constant wobble of the wobble plate .

The present invention provides an alternative type of apparatus for excavating tunnels comprising a driving means , a cutting head driven by the driving means , a first clamping means comprising first clamps located at a front portion of the apparatus and a second clamping means comprising second clamping members located behind the first clamping means and wherein the first clamping means and the second clamping means are operable to move the apparatus forward.

Preferably the first clamping means and the second clamping means are operable with the driving means to move the apparatus in reverse/backwards .

The first clamping means is preferably located at the cutting head.

The first clamping means may be part of the cutting head.

Preferably the second clamping means is located at a mid section of the apparatus . The apparatus may comprise a main body with the driving means located at a rearward end and the cutting head at a forward end.

It is preferred that the first clamping means comprises a plurality of first clamps . Preferably the first clamps are operable to move radially inwardly and outwardly.

The second clamping means preferably comprises a plurality of second clamps .

The second clamps may be operable to move radially inwardly or outwardly.

The apparatus may include a control means to control movement of the first clamping means and the second clamping means .

The first clamping means may include a first ram means including first rams to move the first clamps. The first rams may be hydraulic rams . Each of the first clamps may be operable

independently of the others .

The second clamping means may include a second ram means including second rams to move the second clamps .

The second rams may be hydraulic rams . Each of the second clamps is preferably operable independently of the others .

Preferably the first ram means includes three hydraulic rams .

Preferably the second ram means includes six hydraulic rams.

Each first clamp may comprise a curved member. The curved member may be a generally planar member .

Each clamp may be in the form of a shell segment . Preferably each first clamp comprises at least one hydraulic ram attached to the underside of each curved member .

Each first clamp means preferably comprises three first clamps. Each second clamp means preferably comprises three second clamps .

Preferably the first clamps generally have a greater width than axial length .

The first clamps are preferably symmetrically arranged around the lateral periphery of the cutting head.

If the cutting head is generally cylindrical then the lateral periphery is the circumference .

The first clamps may be arranged radially with outer surfaces having substantially the same radius of curvature .

The outer surfaces of the first clamps may form parts of the circumference of the lateral periphery of the cutting head.

It is preferred that the second clamps generally have a greater axial length than width.

The second clamps may be symmetrically arranged around the lateral periphery of the main body behind the

first clamping means .

The main body may include a shaft . Preferably the cutting head is attached to the front end of the main body. The driving means may comprise a motor .

The motor may be a hydraulic motor which is water driven .

Preferably the apparatus includes a movement means for providing relative movement between the main body and the cutting head.

The movement means preferably provides relative movement between the first clamping means and second clamping means .

The movement means may comprise at least one axially moveable member.

The axially moveable member may be a hydraulic cylinder .

Preferably the movement means comprises a plurality of hydraulic cylinders . According to another aspect of the present invention there is provided a method for moving an apparatus for excavating tunnels comprising a driving means, a main body, a cutting head, a first clamping means having first clamping members located at a front end of the apparatus , a second clamping means having second clamping members located behind the first clamping members and a movement means and including the steps of clamping the first clamps to the inner surface of a tunnel , operating the movement means to draw the second clamping means towards the first clamping means, clamping the second clamping means , disengaging the first clamps from the inner surface of the tunnel and operating the movement means to push the first clamping means forward.

It is preferred that the first clamping means moves forward as the cutting head moves forward and cuts surrounding material .

The movement means may have any of the previously

preferred features .

The apparatus preferably includes steering means for steering the cutting head.

The steering means may comprise a controller which controls different movement of the components of the movement means .

The steering means may include levers which are moveable axially.

Preferably the steering means comprises hydraulic cylinders for actuating the levers.

The levers may comprise cylinder rods/rams . The middle section of the apparatus may include the control means .

The control means may control the steering means and movement means.

The control means preferably controls operation of valves to operate the steering means and movement means .

Preferably the control means in one mode of operation controls the movement means to move the apparatus backwards .

According to a preferred embodiment the apparatus includes water jets to displace material in the tunnel during reversal of the apparatus . According to one aspect of the present invention there is provided a system for controlling operation of a cutting head in an excavating process comprising a controller , a plurality of rams controlled by the controller, a cutting head operated by activation of the rams, wherein the controller actuates the rams whereby an off centre load is placed on the cutting head in a cutting operation .

The controller preferably actuates the rams so that the cutting head simulates a wobble action during the cutting operation.

Preferably during the wobble action an off centre load is applied to the cutting head.

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Preferably the system comprises three axial rams connected to the rear of the cutting head.

The rams may extend from cylinders located on the main body of an excavating machine . The rams may be arranged in a symmetrical pattern .

Preferably the controller includes a plurality of cutting modes for controlling operation of the rams .

It is preferred that the cutting modes include a rotary cutting mode in which rams are controlled to move the cutting head in a rotary motion during a cutting operation, a hammer cutting mode in which rams are controlled to move the cutting head in a reciprocating motion back and forth to make the cutting head impact on a material to be cut, a wobble cutting mode in which rams are controlled to move the cutting head in a wobble motion during a cutting operation .

The controller preferably controls the frequency and intensity of operation of each ram. The controller may include a feedback means for receiving data on a cutting operation by the cutting head . The feedback means may be utilised to optimise a cutting operation for a cutting mode . For example frequency, intensity of operation of one or more rams. The controller may include a speed/torque control means to allow for an alteration to the operating characteristics of the rams to: a . maintain operation of the cutting head within safety limits; or b. maximise cutting operational parameters such as cutting time, cutting force, etc.

During the wobble mode of cutting it is preferred that the axial rams are operated to provide an off-centre load on the cutting head. Preferably the controller controls axial pressure applied by each one of the rams .

Preferably the operational parameters which are

able to be controlled include angular speed, linear speed and torque .

It is preferred that in a wobble mode of operation the cutting head is tilted to a steering angle by differential pressure applied to the rams .

Preferably the system includes sensors for sensing displacement of the rams .

According to another aspect of the present invention there is provided a controller for controlling movement of a cutting head of an excavating apparatus comprising an input configured to receive data relating to a plurality of actuable rams coupled to a cutting head, the data including rotation speed of the rams and torque applied by the rams , an output configured to transmit control signals to the rams and a processor to transmit control signals to the output to actuate the rams to operate the cutting head in one of the plurality of cutting modes , including a wobble cutting mode in which the rams are operated whereby an off centre load is placed on the cutting head in a cutting operation.

Preferably the input includes a plurality of inputs and the output includes a plurality of outputs .

It is preferred that the controller includes a control interface for receiving command signals to select a mode of cutting.

Preferably the controller input is configured to receive data relating to torque and rotational speed of the cutting head.

Preferably the input is configured to receive signals from sensors sensing the angular speed and torque applied to a shaft coupled to the cutting head through the rams.

It is preferred that the processor is adapted to receive data from the sensed signals received at the input and process the data to optimise operation of the cutting head when operating in one of the cutting modes .

It is preferred that the processor includes an

optimising algorithm for optimising one of a plurality of parameters including rotational speed of the cutting head, axial pressure applied by the cutting head, torque applied to the cutting head and differential pressure applied by the rams .

According to another aspect of the present invention there is provided a controller for controlling a cutting head of an excavating apparatus comprising a ram control module for controlling operation of rams coupled to a cutting head, a cutting mode module which provides a plurality of cutting mode options including a wobble mode in which the rams coupled to the cutting head are controlled by the ram control module to provide an off centre load to the cutting head, and a command interface module which is configured to receive command instructions to operate the cutting head in one of the cutting modes .

Preferably the wobble mode includes changing the pitch and yaw of the cutting head by operation of the cutting rams . The cutting mode module may include a hammer mode in which the rams are controlled to reciprocate the cutting head back and forth .

The cutting mode module may include a rotary cutting module in which a shaft coupled with the rams is controlled by a motor control module of the controller to rotate the cutting head.

Preferably the controller includes an adaptive control module in which data received relating to operational characteristics of the cutting head is processed to produce control signals from the ram control module to optimise one or more of the operational parameters of the cutting head.

Preferably the operational parameters include axial pressure, torque, angular speed and linear speed. It is preferred that the operational parameters are optimised to optimise the rate of progress of the cutting head.

According to one embodiment the operational parameters are optimised to prevent breakage of the cutting head.

The controller preferably controls three rams 5 coupled to the cutting head.

The controller may include a steering module, which produces steering signals to the ram control module to apply a differential pressure to the rams to tilt the cutting head in a predetermined direction . l'O It should be understood that a module includes a computer program or part of a computer program, a sub program, a sub routine, hardware or wiring and electronic components .

It should be understood that rams include any

15 linearly actuable device which is able to apply an axial pressure to part of the cutting head. For example rams includes cylinders with pistons .

According to one embodiment the controller comprises a computer program. 0 According to another aspect of the present invention there is provided a controller for controlling movement of a cutting head of an excavating apparatus comprising a ram control module configured to produce ram control signals which control operation of rams coupled to 5 a cutting head and a steering module which is configured to produce steering signals to the ram control module to apply a differential pressure to the rams to tilt the cutting head in a predetermined direction .

The controller preferably includes a command 0 control module which is configured to receive command signals to steer the cutting head in the predetermined direction .

According to the present invention there is provided an apparatus for excavating a tunnel comprising a 5 cutting head with a first coupling portion, a support body with a second coupling portion, and a coupling means which couples the first coupling portion to the second coupling

portion, the coupling means comprising a plurality of links extendible or retractable and each having opposite ends connected to the first coupling portion and the second coupling portion respectively around a central axis of the apparatus and being arranged at an acute angle with respect to one adjacent link at each end, whereby the coupling means can be operated to move the cutting head according to one of a plurality of modes of operation, including partial rotation of the cutting head about the axial direction.

It is preferred that the coupling means provides the cutting head with 6 ° of freedom of movement .

Preferably the links form a truss structure. It is preferred that the links comprise elongate members .

The links may be in the form of linear actuators . Preferably each of the links extends in a direction offset at an acute angle with the axial direction . It is preferred that the links are arranged in pairs at opposite ends of the first and second coupling portions .

Preferably each link pair is placed at the vertex of an equilateral triangle (conceptually) . Preferably the upper and lower triangles are offset by 60° such that the linear actuators form the truss structure.

It is preferred that the cutting head is able to rotate about the axial direction approximately plus or minus 45 ° .

Preferably the links form a zigzag configuration between and around the periphery of each coupling portion. Preferably each link is substantially identical . According to another embodiment each link comprises active link members with joints including one or more of prismatic, spherical and universal joints. It is preferred that one or more joint is

passive .

Preferably the coupling means comprises a Stewart platform or hexapod/Gough platform.

The lateral peripheral length of the coupling portion may be larger than the other .

Alternatively the lateral peripheral length of each coupling portion is substantially the same.

Preferably if the lateral peripheral length of one coupling portion is greater than the other the coupling means comprises three pairs of parallel links.

The coupling means preferably allows 6 ° of freedom for moving the cutting head.

The coupling points of each link on one coupling portion preferably form an irregular hexagon . The coupling means may comprise six active prismatic joints.

The coupling means preferably comprises six UPS legs (U-universal , P-prismatic, S-spherical joints) to connect one connection portion which is a fixed base to the other connection portion which is a moving platform.

Alternatively the coupling means comprises a six PUS or six PSU structure.

According to one embodiment the prismatic joints are active while others are passive. . The body may comprise clamps to fix it to a surrounding surface when the cutting head is in operation .

Preferably the cutting head comprises one of a plurality of modes of operation including: i. percussive mode; ii . drag cutting mode _/ iii . orbital mode; and iv. wobble mode; wherein percussive mode involves reciprocating axial movement, drag cutting mode comprises rotating the cutting head back and forth using bi-directional bits, orbital mode comprises moving the cutting head in an orbital motion or oscillating disk motion and wobble mode

includes providing an off centre load on the cutting head.

It is preferred that the first coupling portion comprises a coupling flange of the cutting head.

It is preferred that the second coupling portion comprises a coupling flange of the support body.

The coupling flange may be in the form of a cylindrical portion with spherical joints for connection to the links .

Preferably each end of the linear actuators comprises a spherical joint.

Preferably each end of the linear actuators comprises a circular lug which is configured to couple with a spherical head of a bolt extending radially from the coupling portions . The cutting head may incorporate front clamps.

The support body may incorporate main clamps . The front clamps are preferably movable radially inwardly and outwardly.

The main clamps are preferably movable inwardly or outwardly .

The apparatus preferably includes a control means for controlling the coupling means .

The control means preferably includes a steering means for steering the cutting head. Preferably the steering means controls the links of the coupling means .

It is preferred that the apparatus excludes a rotatable shaft .

The apparatus preferably excludes a motor , universal joint and bearings.

To minimise water flow for micro tunnelling systems an alternative system for excavating material is provided comprising an excavating apparatus for excavating a tunnel comprising a cutter and motor and feed conduit to feed fluid under pressure to a cutting face and a return conduit to return fluid under pressure and cuttings to a collection zone.

The collection zone may be a reservoir . Preferably the collection zone is located above a ground surface .

The system may include a barrier located behind the cutter to limit pressure leakage from the system.

The barrier may comprise a feed opening through which the feed conduit extends to a front end of the apparatus .

The barrier may comprise a return opening to which a return conduit is attached.

The conduit may be supported on a drum to allow for extension and retraction of the conduit.

Preferably the return conduit has a small bore diameter . It is preferred that the barrier comprises a bladder which covers the excavated tunnel behind the excavating apparatus .

It is preferred that the conduits are supported by a drum. The drum is preferably located above a ground surface .

It is preferred that the cutter is driven by a water powered motor .

It is preferred that the conduits are flexible high pressure hoses.

It is preferred that the feed and return conduits each include a valve control to vary flow rates into and out of the system.

Brief Description of the Drawings A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which :

Figure 1 shows a cross-sectional view of a motor according to the preferred embodiment of the present invention ;

Figure 2 shows a side view of the motor according to the preferred embodiment;

Figure 3 shows an angled view of the motor shown in Figure 2;

Figure 4 shows an exploded view of the motor shown in Figures 1 to 3 ; Figure 5 shows a valve sequencing operation for controlling the motor according to the preferred embodiment;

Figure 6 shows an alternative valve sequencing operation ; Figure 7 shows a cross-sectional view of a motor according to another embodiment of the present invention;

Figure 8A shows a perspective view of a micro tunnelling apparatus in accordance with a preferred embodiment of the invention; Figures 8B to 8E show side views of the micro tunnelling apparatus shown in Figure 8A in different modes of operation;

Figure 9 shows an apparatus for excavating tunnels incorporating a controller according to a preferred embodiment of the present invention;

Figure 10 shows an angled view of an apparatus for excavating a tunnel according to a preferred embodiment of the present invention;

Figure 11 shows a side view of a Stewart platform coupling system used in the apparatus shown in Figure 10; and

Figure 12 shows a schematic diagram of a system for excavating material in accordance with a preferred embodiment of the present invention . Detailed Description of the Drawings

The motor according to the preferred embodiment was designed for a micro tunneller to provide high torque at low speeds and high power in a compact package powered by potable water . The overall length of the motor was minimised to enable a micro tunnelling apparatus to be designed with a tight radius of curvature for movement.

It is preferred that the motor has a length which

is less than half a metre . In addition in its preferred form the motor is a positive displacement hydraulic motor which requires low flow rates of water to minimise the environmental impact and to reduce energy consumption and 5 high pressure flow to maximise power. Due to the low viscosity and high pressure, a piston-based motor was i incorporated as this provides a more positive seal than rotary type pumps .

As shown in Figures 1 to 4 the motor consists of 10 a top section 11 incorporating a central shaft 12 with a lower section which is splined. The splined section 13 is coupled to a wobble plate 14 which is coupled to an axial/roller bearing 15. This bearing 15 is coupled to a wobble plate piece 16 consisting of six radiating pin 15 connectors 17 which are coupled to spherical joints on their outer ends 18, which in turn are coupled to spherical rod ends 19 on the end of axially extending pistons 20.

The wobble plate fitting 16 sits inside the 0 axial/roller bearing 15.

The wobble plate 14, axial/roller bearing 15, wobble plate fitting 16 and piston rods 19 are all concentric with the central longitudinal axis corresponding to the length of the shaft 12. 5 The pistons 20 slide in cylinders 21. The base of the cylinders 21 have valves 22 in a valve chamber 23 separated by a gasket from a chamber 24 housing cylinders 21.

The section of the motor which contains the shaft 0 axial and thrust bearing 15 is immersed in oil and is housed in a chamber 25 located between gasket plates 26 and 27 respectively. A further double gasket sealing section 28, 29 separates chambers 23 and 24. Oil is therefore retained in chambers 24 and 25 between gaskets 5 26 and 28.

A second seal is provided below the first to prevent water that may pass from the first from entering

the oil filled bearing chamber 25. A vent to the outside environment is provided between the two seals 28 and 29.

Figure 4 shows the motor 11 disassembled to allow a clearer view of the motor components. The motor 11 provides a swash plate-type action by fixing a cylinder block 70 and attaching wobble plate 14 directly to shaft 12 via an angled bearing in the form of axial-roller bearing 15. Instead of shoes sliding on a swash plate the load from the pistons 20 is transferred to the angled bearing via spherical rod and contact bearings immersed in oil sliding on stubs . This constitutes the wobble plate mechanism incorporating wobble plate 14, axial/roller bearing 15 and wobble plate fitting 16.

The above arrangement lowers the friction due to the use of rolling element bearings. Axial force from the pistons 20 acts on the outer race 30 of the axial/roller bearing 15 causing inner race 31 to rotate and hence drive the wobble plate and shaft 12.

By fixing the cylinder block eight cylinders are able to be concentrically arranged around the central axis of the motor. A solenoid controlled valve system incorporating the valves 22 is able to be located behind the cylinder chamber 24 and the valves can be sequentially operated by a central controller on the micro tunneller apparatus to electronically simulate normal operation of the motor. Therefore pistons pushing on the down side of the internal wobble plate mechanism are supplied with pressure and those on the upper side are vented to the outside through other solenoid valves . In operation the higher pressure water enters the bottom of the apparatus and is distributed to the inlet of the eight valves 22 through associated pipework 33. Water also bypasses the outside of the motor along conduits 34 in three passages located in the spaces between the four bolt holes. These passages are collected together above the gasket 26 at the bottom of the shaft 12 and supply water to the remainder of the micro tunneller and is

eventually used to flush cuttings from the cutting head of the micro tunneller apparatus .

The valves 22 supply water in sequence to the pistons in accordance with the sequencing provided by the controller. The pistons 20 which move within cylinders 21 reciprocate up and down to provide a wobbling motion for the wobble plate fitting to which they are coupled. The short chamber section between gaskets 28 and 29 serves to distribute water from the valves 22 to the cylinders 21. The pistons separate the water from the oil which resides in the chamber 25 and seals are designed to run with no lubrication and are adequate to prevent passage of water into the oil region .

The force from the pistons 20 is transferred via the spherical rod ends 19 to the inner wobble plate fitting 16 which sits inside the axial/roller bearing 15. This bearing 15 sits inside an offset cylindrical chamber 34 in the bottom of the wobble plate 14. The rod ends 19 slide up and down in the axial direction on short stubs as well as rotating on the spherical balls 18.

The force on the inside race 30 is transferred to the outer race 31 which causes it to spin due to the offset angle . The outer race held by the wobble plate fitting 16 runs in another pair of bearings at the rear of the engine. One of these is another axial (ball) /roller (needle) bearing and the other is needle radial bearing. Both of these use the wobble plate fitting 16 as the inner race of the bearing.

The spline 13 of the shaft 12 is placed inside the wobble plate piece 14. The spline 13 not only transfers torque to the shaft but also allows the shaft to slide up and down the inside of the motor in a lubricated environment to accommodate the change in the length of the micro tunneller apparatus . A seal is provided at the end of the motor to prevent oil leaking down the shaft and

Telfon bearings are placed along the length of the shaft to support it during operation .

Figure 7 shows another embodiment of the invention incorporating design changes to the motor 11.

The design of the wobble plate mechanism incorporates changes to the inner race and outer race 31,30 which are replaced by a single wobble plate race component 50 with an outer race section 51 incorporating a series of equi-spaced radially extending shafts 52 which house inner ends of wobble plate piece 16. The outer ends of the wobble piece 16 are coupled with spherical joints 53.

Figure 7 shows two pistons 54 of the eight pistons which correspond to pistons 20 of Figure 1. These two pistons follow the original design and are located opposite each other in a radial direction, ie. 180° apart. These pistons transfer power from linear to rotary motion and also prevent the rotation of the wobble plate.

The other six pistons represented by item 55 include a spherical joint 56 inside the piston to allow for a small figure eight motion of the wobble plate piece 16. The spherical joints 56 are fixed to the wobble plate piece 16 to prevent radial sliding motion relative to the wobble plate fitting 50.

In the embodiment of the invention shown in Figure 7 the cylinders 57 of the pistons 54, 55 are provided with water seals 58 at their lower ends and oil seals 59 at their upper ends. As shown, water enters the motor 11 through a central water conduit 60 and is distributed through radially extending pipework 61 to valves 62 , each associated with a respective one of the pistons/cylinders 54, 55, 57. Water which is passed by the valves 62 drives the pistons 54,55 and is vented through lateral venting passages 63 extending from a side wall of each of the cylinders 57.

The changes to the design of the motor shown in Figure 7 result in the elimination of gaskets 28 and 29 of the embodiment shown in Figure 1.

The controller which is not shown is normally

located above the top face of the motor casing 35. A normal sequencing operation for control of valves 22 is shown in Figure 5. The sequence shows that four of the valves which are located on the down stroking side of the wobble plate are open whilst the others are closed. While the valves are closed they are venting the contents of the piston to the outside. The rotary motion of the shaft pushes the pistons back to the top and forces the water out. The valves that are experiencing pressure are swapped from valve to valve to cause the linear to rotary valve motion .

The use of the sequenced valves allows operation of the motor in a number of unique ways that allow it to behave like a servo motor. These additional features of the motor include:

Full reversibility. By reversing the sequence of operation of the valves the motor can be reversed easily . This is useful in dealing with cutting head jams.

Full speed control . Changing the frequency of switching changes the operational speed of the motor. This helps reduce stress on the cutting head if hard material is encountered.

Stopping: Closing all valves stops the motor independently of the pump . Braking: Activating all valves forces the motor into a braking mode .

Full Torque at zero speed: All valves can be opened for a period with speed controlled by the frequency of operation . Full torque control: By activating only a single or multiple valves at various times this will result in control of the torque of the motor. This may be essential for protecting the cutting head if rock is encountered. A sequence for quarter torque is shown in Figure 6 in which only a single valve is opened at any time.

As shown in Figure 8A the micro tunnelling apparatus 110 consists of a water powered motor 111 at a

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tail end section thereof, a mid section with steering and navigation controls 112, a first clamping section 113 and a cutting head 114 located at the front of the apparatus .

The cutting head 114 is generally cylindrical in shape and has three peripheral cutting head clamps 115 which are equispaced around the circumference of the cutting head.

Three axial pushing and steering rams 116 extend beyond the front end of the micro tunnelling apparatus and are connected to the rear end of the cutting head 114 via a high torque, compact universal joint. The rearward ends of the rams are connected to the main shaft of the apparatus which extends from the front end to the front end of the water powered motor . The cutting head clamps 115 are supported on radially movable hydraulic rams (not shown) .

The rearward clamps 113 also numbered 3 and are also symmetrically arranged around the circumference of the cylindrically shaped main body of the apparatus . Each clamp 113 is supported at forward and rearward ends by radially movable hydraulic rams .

Both the cutting head clamps 115 and the main clamps 113 are generally planar and have a radius of curvature which closely matches the curvature of the periphery of the cutting head and main body of the micro tunnelling apparatus respectively .

Each of the clamps 113, 115 are controlled automatically by onboard software or alternatively a control station above ground transmits and receives information from a microprocessor controller in the control section of the apparatus . The control section thus controls operation of the motor, rams and clamps. It also contains a navigation computer which uses three differential gyroscopes , three accelerometers and three magnetometers to determine its heading and inclination.

All ram control, valve sequencing and steering is embedded within the apparatus, whilst supervisory control, position

information and condition monitoring information is re- laid to the surface control station. The control station will then be responsible for supervisory control , data logging and control of the surface infrastructure. The apparatus is operated as shown with reference to Figures 8B to 8E . In the first stage, which is the cutting cycle, Figure 8B shows the three major clamps 113 radially extended and engaged to the excavated wall . The front clamps 115 are fully retracted against the outer surface of the cutting head periphery. In this fully retracted mode the clamps provide a generally streamlined outer surface for the cutting head, thus providing minimal obstruction to forward motion of the cutting head 114.

With the clamps as described above a cutting head is operated to cut away the front face of the mine shaft.

In Figure 8C the three hydraulic cylinders are shown fully extended as a result of applying feed pressure to the cutting head while the main body of the apparatus remains fixed in position. It should be noted that only two rams are shown because of the side view hiding the third ram. The three hydraulic rams are also able to rotate as they are connected to the end of the motor shaft .

Proportional control allows a change to the angle of the cutting head to facilitate steering. Thus in such a situation there is a differential pressure applied to the hydraulic rams so that they are extended to different amounts . Thus as an example to move the cutting head downwardly the upper ram(s) would be extended further than the lower ram(s) .

With the cutting head 114 fully extended as shown in Figure 8D, the cutting head clamps 115 are then extended to engage the wall of the tunnel and pressure is released on the rearward clamps 113 so that they are retracted to the outer surface of the mid section of the apparatus . The pressure on the other side of the three axial rams is then used to drag the apparatus and

connecting hoses forward to the next position as shown in Figure 8E . Thus the micro tunneller apparatus moves in a similar fashion to an inch worm in that first the rearward clamps engage the wall of the mine shaft so that the cutting head can be pushed forward and then the forward clamps engage the wall of the mine shaft and the rest of the micro tunneller apparatus behind the cutting head is then effectively pulled forward by the cutting head. In this fashion the axial hydraulic rams when retracted move the micro tunneller forward.

The above process can then be continually repeated or alternatively a reverse sequence of operations can be performed to move the micro tunneller in reverse . This enables the micro tunneller to be reversed out of the tunnel for example if the tunnel prematurely collapses. In addition the micro tunneller is provided with water jets which are directed to the front and side walls of the tunnel to assist with displacement of any material that may remain in the hole . Alternatively to the above tension on the hose behind the micro tunneller may be used to receive the drill head.

As shown in Figure 9 a micro tunnelling apparatus 210 according to one embodiment of the invention consists of a water powered motor 211 at a tail end section, a mid section with a controller 212, a first clamping section 213 and a cutting head 214 with clamps 215.

The cutting head 214 is generally cylindrical in shape and has a cutting face with poly diamond composite (PDC) , drag bits for rotary cutting mode, and commercially available tungsten carbide hammer bits for hammer mode.

Three axial pushing and steering rams 216 extend beyond the front end of the micro tunnelling apparatus and are connected to the rear end of the cutting head 214 via a high torque compact universal joint. The rearward ends of the rams are connected to the main shaft of the apparatus which extends at its rear end to the front end

of a water powered motor .

An on board computer 212 controls operation of the motor 211, rams 216 and clamps 213 and 215. The controller also contains a navigation computer which uses three differential gyroscopes , three accelerometers and three magnetometers to determine its heading and inclination . All ram control , valve sequencing and steering is embedded within the control section 212 of the micro tunnelling apparatus 210. Supervisory control, position information and condition monitoring information is relayed to the controller from a surface control station . The control station will then be responsible for supervisory control, data logging and control of the surface infrastructure. The control section 212 incorporates a computer or microprocessor which is configured to receive command input signals from the surface control station and sensory data relating to torque applied to the cutting head, angular and linear speed of the cutting head, positional information on each of the rams 216 and data relating to the axial pressure applied by each ram. In addition the computer has outputs which control actuators for each of the rams 216 and speed of rotation of the shaft of the water powered motor . The computer is able to control operation of the rams 216 and water powered motor so that the cutting head can offer three different cutting modes . These include a rotary cutting mode in which the shaft spins along with the ram 216 and the cutting head 214. Another cutting mode is hammer mode cutting in which the three axial rams 216 are controlled by the computer to reciprocate the cutting head back and forth to allow the cutting head to impact on the face of the rock being cut. The rock is crushed under the cutting tip and flushed away by cutting fluid. In this mode the motor is controlled to allow the cutting head to be indexed to the next position for the next impact. The controller allows

complete control over the frequency and intensity of the hammer impacts to allow optimisation of the cutting mode without changes to hardware.

Another cutting mode possible is wobble mode cutting. In this mode the controller is able to sequence the operation of the three axial rams so that an off centre load can be placed on the cutting head. This increases the stress on individual bits of the cutting head allowing higher stresses to be placed upon the rock without any increase in the axial or torque loads of the micro tunnel apparatus 210. This type of cutting may increase stress on the rock in the order of ten times a conventional direct hammer mode of cutting .

A basic algorithm for cutting may be obtained as a derivative of the steering action. Basically, the control involves changing the pitch and yaw of the steering angle by the use of a sine and cosine function . The controller operates the rams 216 to tilt the cutting head 214 to a steering angle of 1° by differential pressure on the rams and feedback from the ram displacement sensors . The angle of the head is processed through 360° and this is converted to pitch and yaw steering angles using an algorithm exemplified below.

While "wobble mode" = true Angle = Angle + 10

Pitch_w = tilt * sin (Angle) Yaw_w = tilt * cos (Angle)

Go to steering algorithm to update pitch and yaw information . From timer wait for period = rateps/36

If angle = 360 then angle = 0

Unlike conventional micro tunnellers the cutting head is able to tilt at an angle with respect to the main body of the micro tunnelling apparatus . Thus tunnels can be excavated with a significantly greater angle of curvature to those possible with conventional micro tunnelling apparatuses . The controller can achieve this

by applying differential pressures to the axial rams so that the cutting head can move/tilt in any direction. The amount of tilt is dependent upon the differential length of the axial rams . In addition special spherical coupling joints between the cutting head and the outer ends of the rams 16 may be provided to enhance relative movement therebetween .

As shown in Figure 10 a micro tunnelling . apparatus 311 according to a preferred embodiment of the present invention consists of a cutting head section 312 and a main support body 313. A coupling system consisting of a Stewart platform 314 interconnects a rearward section

315 of the cutting head 312 and a front section 316 of the main body 313. As shown in more detail in Figure 11 the coupling system 314 consists of a zigzag arrangement of linear actuators 317, 318, 319, 320, 321 and 322. These linear actuators form a Stewart platform (or hexapod) and are used instead of axial rams and a motor to provide the actual load and a limited amount of rotation for the cutting head 312.

A Stewart platform is commonly used for flight simulators and as shown in Figure 11 consists of six linear actuators arranged in pairs at opposite ends of two platforms, which in this case are sections 315 and 316 respectively.

The end of each pair is placed at the vertex of a notional equilateral triangle located at sections 315 and

316 respectively. Thus formed upper and lower triangles are offset by 60° such that the linear actuators form a truss structure. The result is a very strong structure which also has 6° freedom of movement for the structure at either end of the linear actuators (in this case the cutting head 312 and main body 313) . As shown in Figure 11 each linear actuator is coupled through a round shaped lug 323a, 323b (at each end) to a spherical ball joint 324, 325 supported on a

radially extending bolt 326, 327 fixed to the circumference of a cylindrical flange 328, 329 of the rearward section 315 and front section 316 of the cutting head 312 and main body 313 respectively. As shown in Figure 11 three pairs of linear actuators are formed for each section 315, 316. Thus the ends of two adjacent linear actuators 319, 322 on flange section 315 are coupled to spherical ball joints 324 which are located in close proximity to each other . The linear actuators 319, 322 extend away from each other at approximately 300° and are connected to ball joints 325 of section 316. These ball joints 325 are spaced apart but are each located in close proximity to another ball joint 325 of another linear actuator 317, 321. The linear actuators 321 and 322 then diverge apart at a similar angle to the angle of divergence between linear actuators 322 and 319 from section 315. The result is three groupings of two spherical ball joints 324 and 325 respectively which are equally spaced around the periphery of a cylindrical flange 328, 329 respectively.

The main body 313 is also provided with radially extending main clamps 330. In a similar fashion the cutting head section 312 is provided with radially extending front clamps 331. By fixing either the cutting head section 312 or the main body 313 to the side walls of a tunnel, a Stewart platform coupling system is able to move the section which is not fixed. Thus as an example assuming the main body section is clamped to the side wall of a tunnel, the cutting head face 332 can be translated in three directions and rotated in three directions, by operation of the linear actuators 317 to 322.

Rotation of the cutting head section 312 can be achieved about the central axis of the apparatus 311 (extending through the centre longitudinally through the apparatus) . The rotation however is not complete and is limited to approximately plus or minus 45 ° . Thus to achieve full continuous rotation it would be necessary to

provide a drive system to . rotate the whole of the main body section 313 and thus the Stewart platform 314 and head section 312 attached to it.

Without having a motor to provide full rotational movement however, it is still possible to obtain useful operating characteristics for the cutting head section 312. For example to cut material it is possible to use a percussive mode in which the linear actuators (which function as rams) move axially to cause an impact, rotate slightly to assist fracture, withdraw and index for the next impact .

The stress on a rock can be increased by impacting the cutting head face at an angle to the rock face , i.e. by providing an off centre load. An orbital motion can also be achieved with the linear actuator arrangement described above in the plane of the rock face to spread the impacts more evenly and to reduce the number of picks .

A drag cutting mode can be achieved by having teeth engage on the rock face with the head rotated back and forth using bidirectional bits. Alternatively the unidirectional bits could be used to cut in only one direction, the head withdrawn rotated back and then reengaged for the next cut . An orbital action cutting can be achieved (for oscillating disk motion) so that more even wear of the bits can be achieved. This could also reduce the required number of bits .

Preferred advantages of the above apparatus include : i. An elimination of motor, shaft, motor controls, universal joint, bearings. ii . More axial force can be placed onto the rock . iii . Fewer moving parts are required. iv. Cutting can be via drag bits or percussive, v. To increase stress on the rock face the

cutter can cut the face at an angle (wobble cut) . vi . An oscillating disk type cutting action can be used. vii . Steering it still possible. viii. Overall length is reduced. ix. A tighter radius of turn is possible. The design of the apparatus described may also be changed so that the linear actuators can incorporate universal, prismatic and spherical joints between the sections 315 and 316. In such a situation one or more of these joints may be active.

As shown in Figure 12 a system according to the preferred embodiment consists of a micro tunneller apparatus 11 incorporating a motor 412 , hydraulic rams 413 and a cutter head. The motor is preferably a water powered motor which drives an axial shaft coupled to the cutter through axial rams 413.

A high pressure feed hose 415 wound on a drum 416 is connected to the micro tunneller 411 and extends through a barrier 417 in the form of a bladder which seals the excavated tunnel behind the micro tunneller 411.

A return hose 418 extends from an opening in the bladder 417 upto the drum 416. The drum is connected to a water pump 419 to pump water to the feed hose 415 and the pump 419 is connected to a water reservoir 420.

Return water and cuttings which pass through the return hose 418 are fed to a water analysis and treatment plant 421 which separates water from the cuttings and returns recycled water via conduit 422 to the water reservoir 420. The cuttings 423 are returned to the ground surface .

In operation water is pumped through the feed hose 415 to drive the water powered motor and to provide water under pressure to the cutting face. The pressurised water serves to flush the cuttings into the return hose 418 through the opening in bladder 417. The water and cuttings return to the surface at high velocity. If the

return hose was not used then large flow rates of water would be needed to return cuttings to the surface . These flow rates would be ten times that needed for typical micro tunnelling machine operations . This high flow however is needed to increase the velocity in the horizontal portion of the hole to a level where turbulent transport of the cuttings can occur.

By using a small diameter return hose 418, the internal velocity can be increased without the need to increase flow rate. A bore hole pressurisation system at the surface is needed to ensure the flow and hence the cuttings return via the return hose rather than the bore hole .

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country .

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention .