WO2012162750A1

WO2012162750A1 - A screw propelled vehicle

Info

Publication number: WO2012162750A1
Application number: PCT/AU2012/000619
Authority: WO
Inventors: Dean Timothy BEAGLEY; Stephen John PERALDINI
Original assignee: Mcdowall Affleck Pty Ltd
Priority date: 2011-06-03
Filing date: 2012-06-01
Publication date: 2012-12-06

Abstract

A screw propelled vehicle is described. The vehicle comprises a chassis and at least two elongate drums coupled to the chassis. Each drum is rotatable and has at least one spiraled flight. Each drum is also arranged, in use, to engage material so as to propel the vehicle as the drums rotate. The vehicle also comprises a drive system for imparting torque to the drums so as to enable the drums to rotate, and a ballast system arranged to enable ballast to be added to or removed from the vehicle.

Description

A SCREW PROPELLED VEHICLE Field of the Invention

The present invention relates to a screw propelled vehicle.

Background of the Invention

Screw propelled vehicles, such as amphirols, can be used to traverse terrain such as mud, residue ponds, marshland and the like. Further, amphirols can be used to reclaim such terrain, for example by being used to create drainage channels to allow for liquid drainage and/or by

compressing the terrain to allow liquid to settle above the terrain to assist with drainage.

Such terrain can cause damage to an amphirol, particularly to its drive system. This in turn leads to down time for the amphirol to allow for repairs to be carried out, therefore adding to the cost of operating the amphirol.

Summary of the Invention

Throughout the specification, the term "screw propelled vehicle" is used to refer to a vehicle that is propelled by the rotation of at least one threaded drum. Such vehicles are also known as "amphirols", and any reference to an "amphirol" is to be taken to also refer to a screw propelled vehicle. Although amphirols can be amphibious, it will be appreciated that the present invention also relates to semi-amphibious vehicles, or vehicles that are designed to traverse mud, residue ponds, marshland and other semi-aquatic terrain. In accordance with an aspect of the present invention, there is provided a screw propelled vehicle comprising: a chassis;

at least two elongate drums coupled to the chassis, each drum being rotatable and having at least one spiraled flight, each drum being arranged, in use, to engage material so as to propel the vehicle as the drums rotate; a drive system for imparting torque to the drums so as to enable the drums to rotate; and

a ballast system arranged to enable ballast to be added to or removed from the vehicle.

In one embodiment, the ballast system is arranged to enable a redistribution of a mass of the vehicle.

In one example, the ballast system comprises one or more ballast tanks coupled to the vehicle, the or each ballast tank being fillable and dischargable with ballast, such as water, such that the mass of the vehicle can be altered and/or redistributed. It will be appreciated that the mass of the vehicle includes a mass of ballast that has been added to the vehicle.

The or each ballast tank may be arranged throughout the vehicle so as to facilitate altering a mass associated with different regions of the vehicle. In one example, the or each ballast tank is arranged symmetrically throughout the vehicle with respect to a longitudinal axis and/or a transverse axis of the vehicle.

In one example, at least one of the drums is a component of the ballast system, the drum being arranged to enable ballast to be added to or removed from the drum. In one embodiment, the drum is arranged to enable a

redistribution of a mass of the vehicle. In one

embodiment, at least a portion of the drum is arranged so as to be fillable and dischargable with ballast. That is, at least a portion of the drum may function as a ballast tank .

Having the drum functioning as a component of the ballast system may be advantageous in improving a stability of the vehicle since increasing the mass of the drum lowers a centre of gravity of the vehicle, and can reduce or even eliminate the number of ballast tanks that may otherwise be reguired as components of the ballast system. The ballast system may provide the advantage of enabling the mass of the vehicle to be altered, thereby providing means for controlling an amount of compaction of the material as the vehicle moves over the material. This, in turn, also provides a means for controlling an amount of dewatering of the material as a result of the compaction of the material.

The ballast system may also provide the advantage of allowing a pitch, roll and/or yaw of the vehicle to be controlled.

In one embodiment, the ballast system is controllable, such as via a control system, so as to enable a mass of the vehicle to be altered and/or redistributed.

In accordance with a further aspect of the present invention, there is provided a screw propelled vehicle comprising : a chassis;

at least two elongate drums coupled to the chassis, each drum being rotatable and having at least one spiraled flight, each drum being arranged, in use, to engage material so as to propel the vehicle as the drums rotate; and

a drive system for imparting torque to the drums so as to enable the drums to rotate; wherein

at least one of the drums comprises a plurality of spiraled flights disposed on an outer surface of the at least one drum.

In one example, the drum comprises a plurality of flights having a double helix-like configuration. It will be appreciated that the drum may comprise any number of flights .

The flights may have a pitch in the range of 600mm to 3750mm.

A helix angle of the flights with respect to an outer surface of the drum may be in the range of 45^° to 81^°.

The flights may have a height in the range of 75mm to 200mm, and a thickness in the range of 6mm to 20mm.

Further, the flights may vary in height in the range of 75mm to 200mm along a length of the drum. The length of the drum along which the flights vary in height may include a length of at least one of the cylindrical portions.

Each flight may extend for one or more revolutions about an axis of rotation of the drum and along a length of the drum. In one specific embodiment, each flight extends for substantially 4½ revolutions about the axis of rotation of the drum and along a length of the drum. In an alternative embodiment, the drum comprises four flights, each flight extending for between 1 and 3 revolutions about the axis of rotation of the drum and along the length of the drum.

The drum may comprise a central cylindrical portion that is abutted at each end by respective contiguous

frustoconical portions.

The cylindrical and frustoconical portions may be formed from rolled steel plate. In one embodiment, each frustoconical portion is adapted to be coupled to a bearing assembly or a drive shaft. In one example, each frustoconical portion comprises a flange portion, the flange portion being adapted to be coupled to a bearing assembly or a drive assembly.

The drum may comprise strengthening elements arranged to increase a strength of the drum. In one example, the strengthening elements comprise stiffener plates arranged at each end, and internal of, the cylindrical portion so as to provide support for the cylindrical portion. The stiffener plates may have a substantially annular shape.

The strengthening elements may also comprise a plurality of substantially triangular stiffener plates arranged so as to abut an outer surface of a respective stiffener plate and an inner surface of a respective frustoconical portion, the substantially triangular stiffener plates providing support for the respective frustoconical portion .

The strengthening elements may also comprise a plurality of substantially triangular stiffener plates arranged to abut an adjacent surface of a respective flange portion and an outer surface of a respective frustoconical portion so as to provide support for the flange and/or

frustoconical portions.

In one embodiment, the drum comprises wear plates . In one example, the drum comprises a wear resistant strip surrounding an outer region of at least one end of the cylindrical portion, and a wear resistant strip

surrounding an outer region of at least one frustoconical portion. Each wear resistant strip may be formed from rolled steel plate. Each wear resistant strip may also be adapted to receive wear plates. The wear plates may be arranged in a substantially crisscross pattern. Further, or alternatively, at least one wear resistant strip may comprise weld beads . The weld beads may be arranged in a substantially crisscross pattern.

Components of the drum may be welded together in a manner so as to strengthen the drum. In one example, a join between the wear resistant strip surrounding the outer region of the end of the cylindrical portion and the wear resistant strip surrounding the outer region of an adjacent frustoconical portion is welded so as to protect the join.

The drum may have a length in the range of 3000mm to 7000mm. The cylindrical portion may have a diameter in the range of 900mm to 1600mm. At least one frustoconical portion may be arranged so as to provide a substantially smooth transition between an outer surface of the frustoconical portion and an outer surface of its respective cylindrical portion. In one embodiment, this is achieved by varying an angle between a tangent of the outer surface of the frustoconical portion and a radial axis of the drum. In one embodiment, the angle between the tangent of the outer surface of the frustoconical portion and the radial axis of the drum is substantially 90° at a region where the frustoconical portion transitions to the cylindrical portion. The angle between the tangent of the outer surface of the

frustoconical portion and the radial axis of the drum may reduce to an angle that is less than 90° at a region remote from the transition between the frustoconical portion and the cylindrical portion.

It will be appreciated that walls of the frustoconical portions may curve towards the flange portions, for example in a hemispherical fashion.

At least a portion of the drum may comprise a friction reducing coating. In one particular example, the drum comprises stainless steel. The stainless steel may be coated in friction reducing coating.

a drive system for imparting torque tothe drums so as to enable the drums to rotate; wherein

each drum is coupled to the chassis via a drive assembly, each drive assembly being arranged to allow for the transmission of power from a power source of the drive system to a respective drum while substantially reducing, or preventing, ingress of the material into an interior of the drive assembly and/or an interior of the drums.

At least one drive assembly may comprise a drive motor and a coupling assembly for coupling the drive motor to a respective drum, the coupling assembly comprising a bearing and sealing assembly and a drive shaft, the drive shaft being arranged to be received by the drive motor and the bearing and sealing assembly being arranged to substantially reduce, or prevent, ingress of the material into the interior of the drive assembly and/or an interior of the drums.

The bearing and sealing assembly may comprise a bearing assembly for receiving the drive shaft and a first seal assembly for sealing a junction between the drive shaft and the bearing assembly.

In one embodiment, the first seal assembly comprises first and second bearing assembly seals and a sealing ring, the first bearing assembly seal being received in a recess in a surface of the drive shaft adjacent the junction, the second bearing assembly seal abutting the first bearing assembly seal and being received in a recess in a surface of the bearing assembly adjacent the junction, the sealing ring encircling the abutment between the first and second bearing seals and being received in further recesses in the adjacent surfaces of each of the drive shaft and the bearing assembly. The sealing ring may comprise polyurethane .

The bearing and sealing assembly may comprise a second seal assembly for providing a seal between the bearing assembly and the drive motor. In one embodiment, the second seal assembly comprises a drive motor seal arranged between the bearing assembly and the drive motor. An inner seal of the drive motor seal may be retained against the bearing assembly by an inner seal retainer and an outer seal of the drive motor seal may be retained against the drive motor by an outer seal retainer.

A drive motor seal adapter may be provided between the outer seal and the drive motor and coupled to the drive motor so as to provide a means for indirectly coupling the outer seal to the drive motor.

The drive motor seal adapter may comprise sealable holes, a cavity of the drive motor seal adapter being filled with grease via the holes prior to sealing the holes. The bearing and sealing assembly may comprise a deflector assembly arranged so as to encircle the drive motor seal. The deflector assembly may comprise at least one aperture so as to facilitate drainage and flushing of the deflector assembly.

For further sealing, a seal may be fitted to the drive shaft at a region adjacent drive motor engaging teeth of the drive shaft. This seal may be fitted to the drive shaft prior to assembly of the drive motor onto the drive shaft . The drive shaft may be formed from one piece, as opposed to two piece drive shafts which are typically used in conventional drive assemblies and which are prone to failure at a joint between the two drive shaft pieces. A one piece drive shaft may also assist in reducing a distance that the coupled drive motor extends towards the rear of the vehicle, thereby reducing a need to provide ballast at an opposite end of the vehicle to balance the vehicle . The coupling assembly may be used for any appropriate application, and is not restricted to use with the vehicle .

The coupling assembly may be arranged so as to allow its respective drum to be filled and emptied with ballast. In one embodiment, the coupling assembly comprises a ballast inlet and outlet in fluid communication with an interior of the drum so as to allow the drum to be filled and emptied with ballast.

In each of the above aspects of the present invention, the drums may be arranged so as to provide buoyancy to the vehicle . Brief Description of the Drawings

In order that the present invention may be more clearly ascertained, embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure la is a rear isometric view of a screw propelled vehicle in accordance with an embodiment of the present invention;

Figure lb is a rear view of the vehicle of Figure la;

Figure lc is a front perspective view of the vehicle of Figure la and showing a ballast system;

Figure 2 is an isometric view of a ballast tank the ballast system of Figure lc;

Figure 3 is a side view of a drum of the vehicle Figure la showing internal ballast tanks;

Figure 4a is a side view of a drum of the vehicle of Figure la;

Figure 4b is a front view of a flange of the drum of Figure 4a;

Figure 4c is a front view of a stiffener plate of the drum of Figure 4a;

Figure 4d is a side view of a stiffener plate of Figure 4a; Figure 4e is a side view of a stiffener plate of Figure 4a; Figure 4f is a schematic diagram of joins between components of the drum of Figure 4a showing the placement of welds;

Figure 4g is a side view of an alternative drum of the vehicle of Figure la;

Figure 5 is a schematic diagram of a drive motor and coupling assembly of the vehicle of Figure la; and Figure 6 is an exploded view diagram of the coupling assembly of Figure 5.

Detailed Description of the Embodiments

Figure 1 shows a screw propelled vehicle 10 in accordance with an embodiment of the present invention. The vehicle 10 can be used for traversing terrain such as residue ponds and muddy environments that would otherwise be inaccessible to conventional earthmoving equipment. The vehicle 10 can therefore be used to assist with reclaiming such terrain, for example by being used to form drainage channels or by compressing the terrain to allow liquid to settle on top of the terrain for more convenient drainage of the liquid. In this example, the vehicle 10 comprises a chassis 12, two elongate drums 14 coupled to the chassis 12 and a drive system for imparting torque to the drums 14. The chassis comprises an operator cabin 16 from which the vehicle 10 can be operated and comprises controls for operating the vehicle 10, such as a joystick. Each drum 14 is rotatable and comprises at least one spiraled flight 18. The drums 14 function so as to propel the vehicle over the terrain, and to add buoyancy to the vehicle 10 so as to prevent the vehicle 10 from sinking into the terrain.

The drums 14 are arranged, in use, to engage material such as mud, and to propel the vehicle 10 as the drums 14 rotate. The drive system comprises an engine 20, a hydraulic system 22, and hydraulic drive motors 24 and associated coupling assemblies 100 (see Figure 6) for coupling each drive motor 24 to a respective first end of each drum 14. The drive system is arranged to transfer power from the engine 20 via the hydraulic system 22 to the hydraulic drive motors 24 to rotate the drums 14. Each drum 14 is coupled at a second end thereof to the chassis 12 via a respective bearing assembly 25. The drums 14 may be substantially hollow, or at least partially hollow, thereby increasing the buoyancy of the vehicle 10.

The vehicle 10 also comprises a ballast system 26 (see Figure lc) arranged so as to enable ballast to be added to or removed from the vehicle 10. In this example, the ballast system 26 comprises a plurality of ballast tanks 28, each ballast tank 28 being coupled to the chassis 12 and being arranged to be fillable and dischargable with ballast, such as water. As such, and with reference to Figure 2, each ballast tank 28 comprises an inlet 30 disposed on a top surface of the ballast tank 28, the inlet 30 being arranged to allow the ballast tank 28 to be filled with ballast. The inlet 30 may be a one way valve, or be arranged to receive a cap so as to seal the ballast tank 28 after the ballast tank 28 has been filled with the desired amount of ballast. The ballast tank 28 also comprises an outlet 32 disposed on a lower surface of the ballast tank 28, the outlet 32 being arranged to allow the ballast tank 28 to be emptied. The outlet 32 may be a tap, or otherwise adapted so as to allow an amount of ballast to be controllably released from the ballast tank 28.

Each ballast tank 28 can be filled and/or emptied to a desired amount, and therefore a mass of the vehicle 10 can be increased at locations where the ballast tanks 28 are situated. It will be appreciated that the mass of the vehicle includes a mass of ballast that has been added to the vehicle.

This allows for trimming of the vehicle 10. In this example, the ballast tanks 28 are distributed

substantially uniformly throughout the vehicle, with a ballast tank 28 being located at each of a forward left, forward right, rear left and rear right position of the vehicle 10. This arrangement facilitates control of a pitch and roll of the vehicle.

In one embodiment, the ballast system 26 is controllable, such as via a control system (not shown) , so as to allow a mass of the vehicle 10 to be altered and/or redistributed in an automated fashion.

The control system can be arranged to receive instructions from an operator of the vehicle, the instructions relating to a desired alteration and/or redistribution of the mass of the vehicle 10, and to instruct the ballast system 26 to carry out the desired alteration and/or redistribution of the mass of the vehicle 10.

The control system will typically comprise an interface system, the interface system comprising a monitor for displaying relevant information to the vehicle operator, and an input device such as a keyboard to enable the vehicle operator to input instructions to the control system. The control system will also typically comprise a computing device that is arranged to receive instructions from the interface system, process the instructions using a processor of the computing device, and instruct the ballast system 26 to change or redistribute an amount of ballast of the system 26 so as to effect the alteration and/or redistribution of the mass of the vehicle 10.

In one example, individual ballast tanks or ballast compartments of the ballast system 26 are in fluid communication with one another, for example via a valve and pump system, such that the ballast system 26 can redistribute the ballast so as to redistribute the mass of the vehicle 10.

It will be appreciated that the drums 14 may be used as a component of the ballast system 26, either solely or in addition to the ballast tanks 28. For example, at least one drum 14 can be arranged to enable ballast to be added to or removed from the drum. In one embodiment, the drum is arranged to enable a redistribution of a mass of the vehicle. As such, and with reference to Figure 3, at least a portion of the drum 14 can be arranged so as to be fillable and dischargable with ballast. For example the drum 14, which would otherwise be substantially hollow, can comprise forward and rear ballast regions 34, 36 and having a similar configuration to the ballast tanks 28 for receiving and emptying ballast, therefore enabling the mass of the drum 14 to be altered and/or redistributed.

Providing a drum 14 arranged to have an alterable and/or redistributable mass allows the drum 14 to function as a component of the ballast system 26 and may provide the advantage of improving a stability of the vehicle 10. For example, the mass of the drums 14 can be increased, thereby lowering a centre of gravity of the vehicle 10.

Further, the ballast system 26 in general provides the advantage of enabling the mass of the vehicle 10 to be altered, thereby providing means for controlling an amount of compaction of the material as the vehicle moves over the material. This, in turn, also provides a means for controlling an amount of dewatering of the material as a result of the compaction of the material.

The ballast system 26 also provides the advantage of allowing a pitch of the vehicle 10 to be controlled, and/or a roll of the vehicle to be controlled. The ballast system 26 therefore allows the vehicle 10 to be readily adapted to different terrain scenarios and conditions.

A more detailed description of the drums 14 will now be provided with reference to Figure 4. Referring initially to Figure 4a, the drum 14 comprises a central cylindrical portion 40 abutted by two

frustoconical portions 42, each of the cylindrical and frustoconical portions 40, 42 being formed, in this example, from rolled steel plate. A steel flange 44 is attached, such as by welding, to an end of each

frustoconical portion 42. A front view of the flange 44 is shown in Figure 4b. The flange 44 comprises a plurality of holes 46 and a spigot 47 for facilitating coupling of each flange 44 to a respective bearing assembly 25 or drive shaft 104 of the drive motor 24.

The drum 14 also comprises first and second flights 48, 50 that spiral in a helical fashion along an outer surface of the drum 14. In this example, the flights 48, 50 are arranged at 180° to each other with respect to the outer cylindrical surface of the drum 14 such that they form a double helix configuration. It will be appreciated that any number of flights can be arranged along the outer surface of the drum 14, preferably with the flights being spaced apart from each other by equal amounts. An example of a drum 14 comprising four flights is described later with reference to Figure 4g.

The flights 48, 50 are formed from steel and are welded to the outer surface of the drum 14. Each flight 48, 50 extends for approximately 4 ½ revolutions about an axis of rotation of the drum 14 and along a length of the drum 14, approximately 4 revolutions of which are along a length of the cylindrical portion 40. It will be appreciated that each flight may extend for one or more revolutions about an axis of rotation of the drum 14 and along a length of the drum 14.

The drum 14 also comprises a number of strengthening and wear resistant features, which will now be described. The drum 14 comprises stiffener plates 52 arranged at each end, and internal, of the cylindrical portion 40 so as to provide support for the cylindrical portion 40. The stiffener plates 52, which have an annular shape as shown in Figure 4c, are formed from steel and are welded to an inner surface at end regions of the cylindrical portion 40.

The drum 14 also comprises a plurality of triangular stiffener plates 54 (see Figure 4d) arranged so as to abut an outer surface of a respective stiffener plate 52 and an inner surface of a respective frustoconical portion 42. The stiffener plates 54 function so as to provide support for the frustoconical portions 42. In this example, each frustoconical portion 42 is supported by four stiffener plates 54, each stiffener plate 54 being welded into position, the stiffener plates 54 being spaced

equidistantly around the inner surface of the

frustoconical portions 42.

The drum 14 also comprises a plurality of substantially triangular stiffener plates 56 (see Figure 4e) arranged so as to abut an adjacent surface of a respective flange 44 and an adjacent outer surface of each frustoconical portion 42. The stiffener plates 56 can function to provide support for the flange 44 and/or the frustoconical portions 42. In this example, each frustoconical portion 42/flange 44 is supported by eight stiffener plates 56, each stiffener plate 56 being welded into position and being spaced equidistantly around the outer surface of the frustoconical portions 42. The drums 14 may also comprise wear plates or have some appropriate form of wear reducing treatment. In this example, each drum 14 comprises a wear resistant strip 58 surrounding each end of the cylindrical portion 40, and a wear resistant strip 60 surrounding a region of each frustoconical portion 42 adjacent the cylindrical portion 40. Each wear resistant strip 58, 60 is formed from rolled steel plate. The wear resistant strips 58, 60 are adapted so as to receive high wear weld beads 62. The weld beads 62 are arranged in a crisscross pattern. The drums 14 may also be arranged to receive wear plates arranged in a crisscross manner .

Components of the drum 14 can be welded together in a manner so as to further strengthen the drum 14 and/or to reduce an amount of wear to the drum 14. An example of this is shown in Figure 4f. Figure 4f shows a partial cross section of a region at which the frustoconical portion 42 is joined to the cylindrical portion 40. In particular, the cylindrical portion 40 is welded to the stiffener plate 52 at an inner corner therebetween so as to form weld 64. The frustoconical portion 42, stiffener plate 54 and stiffener plate 52 are welded at a join therebetween to form weld 66. A weld 68 is provided to join the cylindrical portion 40, frustoconical portion 42 and wear resistant strips 58, 60 together, with a further weld 70 being provided between the wear resistant strips 58, 60 so as to provide additional protection for the joint therebetween. It will be appreciated that surfaces of the drum 14 that can come into contact with the material can be coated in a friction reducing coating so as to reduce the amount of friction between such surfaces and the material, thereby increasing an efficiency of the vehicle 10 and further reducing wear. Such surfaces may also be coated in a wear reducing coating so as to reduce wear.

It will also be appreciated that the components of the drum 14 can be formed from any appropriate material, and particularly from materials that can assist in reducing wear to the drum 14. For example, components of the drum 14 can be formed from stainless steel. In the example shown in Figure 4a, the cylindrical portion 40 has a length of 4800mm, the frustoconical portions 42 have a length of 680mm, and the flights 48, 50 have a pitch of 1250mm, although it will be appreciated that the dimensions of the cylindrical portion 40, the

frustoconical portions 42 and the flights 48, 50 may be any appropriate dimensions. For example, the flights 48, 50 may have a pitch in a range of 600mm to 3750mm.

A helix angle of the flights 48, 50 with respect to an outer surface of the drum 14 may be in the range of 45^° to 81^°.

The flights 48, 50 may have a height in the range of 75mm to 200mm, and a thickness in the range of 6mm to 20mm. Further, the flights 48, 50 may vary in height in the range of 75mm to 200mmm along a length of the drum 14. The length of the drum along which the flights vary in height may include a length of at least one of the cylindrical portions .

The drum 14 may have a length in the range of 3000mm to 7000mm.

The cylindrical portion 40 may have a diameter in the range of 900mm to 1600mm. In the example of Figure 4a, the cylindrical portion 40 has a diameter of approximately 1200mm. In an alternative embodiment, the cylindrical portion 40 has a diameter of 1400mm.

Each frustoconical portion 42 can be arranged so as to provide a substantially smooth transition between an outer surface of the frustoconical portion 42 and an outer surface of its respective cylindrical portion 40. In one embodiment, this is achieved by varying an angle between a tangent of the outer surface of the frustoconical portion 42 and a radial axis of the drum 14. In one embodiment, the angle between the tangent of the outer surface of the frustoconical portion 42 and the radial axis of the drum

14 is substantially 90° at a region where the frustoconical portion 42 transitions to the cylindrical portion 40. The angle between the tangent of the outer surface of the frustoconical portion 42 and the radial axis of the drum 14 can reduce to an angle less than 90° at a region remote from the transition between the frustoconical portion 42 and the cylindrical portion 40

It will be appreciated that walls of the frustoconical portions 42 may curve towards the flange portions 44, for example in a hemispherical fashion.

Figure 4g illustrates an example drum 14' comprising four flights 48, 49, 50, 51. The flights 48, 49, 50, 51 have a different pitch than flights of the drum 14 of Figure 4a. In particular, the flights 48, 49, 50, 51 of drum 14' have a pitch of 2500mm and extend for approximately 2 rotations about an axis of rotation of the drum 14' along a length of the cylindrical portion 40. It will be appreciated that the flights may extend for between 1 and 3 revolutions about the axis of rotation of the drum 14 and along the length of the drum 14. The flights 48, 49, 50, 51 are arranged at 90° to each other with respect to the outer cylindrical surface of the drum 14. In this example, the cylindrical portion is 4800mm in length. The drum 14' of Figure 4g shares all other features with the drum 14 of Figure 4a, including wear resistant strips and high wear weld beads 62 (not shown in Figure 4g) and the same strengthening features, including stiffener plates 52, 54, 56.

Providing a drum 14' having an increased number of flights can increase a maximum ground speed of the vehicle 10. In this example, the diameter of the cylindrical portion 40 of the drum 14' is 1200mm, although it will be appreciated that the diameter of the drum 14' may be any appropriate diameter, including a diameter of 1400mm. It will also be appreciated that increasing a diameter of the drum 14' can increase a maximum ground speed of the vehicle 10. The drive system will now be described in more detail.

As described earlier with reference to Figure 1, each drum 14 is driven by a respective hydraulic motor 24. The hydraulic motors 24 in turn ultimately derive their power from the engine 20 by way of the hydraulic system 22, the hydraulic system 22 comprising a hydraulic oil reservoir and hydraulic lines (not shown) for transferring power from the engine 20 to the hydraulic motors 24.

Each hydraulic motor 24 is coupled to its respective drum 14 via the coupling assembly 100 shown in Figures 5 and 6. The coupling assembly 100 comprises a bearing and sealing assembly 102 and a drive shaft 104, the drive shaft 104 being arranged to be received by the motor 24 and coupled to the flange 44 of the drum 14.

The bearing and sealing assembly 102 functions as a bearing for the drive shaft 104 and as a sealing system for preventing the ingress of undesirable material, such as ground material like mud, into components of the drive motor 24 and coupling assembly 100. In particular, the bearing and sealing assembly 102 is arranged so as to prevent the ingress of material into a bearing 106 of the bearing and sealing assembly 102 and/or the drive motor 24.

The bearing and sealing assembly 102 comprises a bearing 106 and a bearing housing 108 arranged to receive the bearing 106. The bearing 106 receives a sleeve 110 and nut 112, the sleeve 110 and nut 112 being arranged to receive the drive shaft 104. The bearing and sealing assembly 102 is sealed at a junction 114 between the drive shaft 104 and the bearing housing 108 by first and second bearing assembly seals 116, 118 and a polyurethane ring 120. The first bearing assembly seal 116 is received in a correspondingly shaped recess in a surface of the drive shaft 104 adjacent the junction 114. The second bearing assembly seal 118 abuts the first bearing assembly seal 116 and is received in a correspondingly shaped recess in a surface of the bearing housing 108 adjacent the junction 114. The polyurethane ring 120 encircles the abutment between the first and second bearing seals 116, 118 and is received in

correspondingly shaped recesses in the adjacent surfaces of each of the drive shaft 104 and bearing housing 108.

The bearing and sealing assembly 102 is also sealed at the drive motor 24. This sealing is provided by the following components .

A bearing housing cover 122 is coupled to the bearing housing assembly 108, such as by screws, with an o-ring 124 providing sealing therebetween. A drive motor seal adapter 126 is coupled to the drive motor 24, such as by screws, with an o-ring 128 providing sealing therebetween. The screws are sealed with a silicone elastomer after tightening. An end of the drive motor seal adapter 126 opposite the drive motor 24 is arranged to receive a seal 130 for providing a seal between the motor seal adapter 126 and the drive shaft 104.

The drive motor seal adapter 126 comprises sealable holes, a cavity of the drive motor seal adapter 126 being filled with grease via the holes prior to sealing the holes. A drive motor seal 132 is arranged between the bearing housing cover 122 and the drive motor seal adapter 126. The drive motor seal 132 is retained by an inner seal retainer 134 and an outer seal retainer 136. The inner seal retainer 134 sandwiches an inner seal 138 of the drive motor seal 132 between the inner seal retainer 134 and the bearing housing cover 122 and is held by bolts extending through the inner seal retainer 134 and the inner seal 138 into corresponding holes of the bearing housing cover 122, the bolts being tightened against the inner seal retainer 134 with a spring washer arranged therebetween. The outer seal retainer 136 sandwiches an outer seal 140 of the drive motor seal 132 between the outer seal retainer 136 and the drive motor seal adapter 126 and is held by bolts extending through the outer seal retainer 136 and the outer seal 140 into corresponding holes of the drive motor seal adapter 126, the bolts being tightened against the outer seal retainer 136 with a spring washer arranged therebetween.

Further protection is provided by a deflector assembly comprising upper and lower deflectors 142, 144 which are arranged so as to encircle the drive motor seal 132, the upper and lower deflectors being bolted to the drive motor seal adapter 126. Each of the upper and lower deflectors 142, 144 comprise a hole so as to facilitate drainage and flushing of the deflector assembly.

For further sealing, an o-ring 146 is fitted to the drive shaft 104 at a corresponding recess 148 adjacent drive motor engaging teeth 150. The o-ring 146 is fitted to the drive shaft 104 prior to assembly of the drive motor 24 onto the drive shaft 104. In this example, the drive shaft 104 is formed from one piece, as opposed to two piece drive shafts which are typically used in conventional drive assemblies and which are prone to failure at a joint between the two drive shaft pieces. The one piece drive shaft 104 can also assist in reducing the distance that the coupled drive motor 24 extends towards the rear of the vehicle 10, thereby reducing the need to provide ballast at an opposite end of the vehicle 10 to balance the vehicle 10.

The coupling assembly 100 may be arranged so as to allow its respective drum 14 to be filled and emptied with ballast. For example, the coupling assembly 100 can comprise a ballast inlet and outlet in fluid communication with an interior of the drum 14 so as to allow the drum 14 to be filled and emptied with ballast.

Further, it will be appreciated that the coupling assembly 100 could be used for any appropriate application, and is not restricted to use with the vehicle 10 described hereinabove .

The drive assembly may be arranged so as to allow the filling and discharging of the suitable substance from the drums .

Although the invention has been described with reference to particular examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. 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.

Claims

Claims :

1. A screw propelled vehicle comprising:

a chassis;

2. The vehicle of claim 1, wherein the ballast system is arranged to enable a redistribution of a mass of the vehicle .

3. The vehicle of claim 2, wherein the ballast system comprises one or more ballast tanks coupled to the vehicle, the or each ballast tank being fillable and dischargable with ballast such that the mass of the vehicle can be altered and/or redistributed.

4. The vehicle of claim 3, wherein the or each ballast tank is arranged throughout the vehicle so as to

facilitate altering a mass associated with different regions of the vehicle.

5. The vehicle of claim 4, wherein the or each ballast tank is arranged symmetrically throughout the vehicle with respect to a longitudinal axis and/or a transverse axis of the vehicle.

6. The vehicle of any of the preceding claims, wherein at least one of the drums is a component of the ballast system, the drum being arranged to enable ballast to be added to or removed from the drum.

7. The vehicle of claim 6, wherein the drum is arranged to enable a redistribution of a mass of the vehicle.

8. The vehicle of any one of the preceding claims wherein the ballast system is arranged to enable a pitch, roll and/or yaw of the vehicle to be controlled.

9. The vehicle of any one of the preceding claims, wherein the vehicle comprises a control system that is arranged to control the ballast system so as to enable a mass of the vehicle to be altered and/or redistributed.

10. A screw propelled vehicle comprising:

a chassis;

11. The vehicle of claim 10, wherein each flight extends for one or more revolutions about an axis of rotation of the drum and along a length of the drum.

12. The vehicle of claim 10 or claim 11, wherein the drum comprises a plurality of flights having a double helixlike configuration.

13. The vehicle of claim 12, wherein each flight extends for substantially 4½ revolutions about an axis of rotation of the drum and along a length of the drum.

14. The vehicle of claim 10 or claim 11, wherein the drum comprises four spiraled flights.

15. The vehicle of claim 14, wherein each flight extends for between 1 and 3 revolutions about the axis of rotation of the drum and along the length of the drum.

16. The vehicle of any one of claims 10 to 15, wherein the flights have a pitch in the range of 600mm to 3750mm.

17. The vehicle of any one of claims 10 to 16, wherein a helix angle of the flights with respect to an outer surface of the drum may be in the range of 45^° to 81^°.

18. The vehicle of any one of claims 10 to 17, wherein the flights have a height in the range of 75mm to 200mm.

19. The vehicle of any one of claims 10 to 18, wherein the flights have a thickness in the range of 6mm to 20mm.

20. The vehicle of any one of claims 10 to 17, wherein the flights vary in height in the range of 75mm to 200mm along a length of the drum.

21. The vehicle of any one of claims 10 to 18, wherein the drum comprises a central cylindrical portion that is abutted at each end by respective contiguous frustoconical portions .

22. The vehicle of claim 22, wherein the cylindrical and frustoconical portions are formed from rolled steel plate.

23. The vehicle of claim 21 or claim 22, wherein each frustoconical portion is adapted to be coupled to a bearing assembly or a drive shaft.

24. The vehicle of claim 23, wherein each frustoconical portion comprises a flange portion, the flange portion being adapted to be coupled to a bearing assembly or a drive assembly.

25. The vehicle of claim 24, wherein walls of the frustoconical portions curve towards the flange portions.

26. The vehicle of any one of claims 21 to 25, wherein at least one frustoconical portion is arranged so as to provide a substantially smooth transition between an outer surface of the frustoconical portion and an outer surface of its respective cylindrical portion.

27. The vehicle of claim 26, wherein an angle between a tangent of the outer surface of the frustoconical portion and a radial axis of the drum is substantially 90° at a region where the frustoconical portion transitions to the cylindrical portion, and wherein the angle between the tangent of the outer surface of the frustoconical portion and the radial axis of the drum reduces to an angle that is less than 90° at a region remote from the transition between the frustoconical portion and the cylindrical portion .

28. The vehicle of any one of claims 10 to 27, wherein the drum comprises strengthening elements arranged to increase a strength of the drum.

29. The vehicle of claim 28, wherein the strengthening elements comprise stiffener plates arranged at each end, and internal of, the cylindrical portion so as to provide support for the cylindrical portion.

30. The vehicle of claim 29, wherein the stiffener plates have a substantially annular shape.

31. The vehicle of any one of claims 28 to 30, wherein the strengthening elements comprise a plurality of substantially triangular stiffener plates arranged so as to abut an outer surface of a respective stiffener plate and an inner surface of a respective frustoconical portion, the substantially triangular stiffener plates providing support for the respective frustoconical portion .

32. The vehicle of any one of claims 28 to 31, wherein the strengthening elements comprise a plurality of substantially triangular stiffener plates arranged to abut an adjacent surface of a respective flange portion and an outer surface of a respective frustoconical portion so as to provide support for the flange and/or frustoconical portions .

33. The vehicle of any one of claims 10 to 32, wherein the drum comprises wear plates.

34. The vehicle of any one of claims 10 to 33, wherein the drum comprises a wear resistant strip surrounding an outer region of at least one end of a cylindrical portion of the drum, and a wear resistant strip surrounding an outer region of at least one adjacent frustoconical end portion of the drum.

35. The vehicle of claim 34, wherein each wear resistant strip is formed from rolled steel plate.

36. The vehicle of claim 34 or claim 35, wherein each wear resistant strip is adapted to receive wear plates.

37. The vehicle of claim 36, wherein the wear plates are arranged in a substantially crisscross pattern.

38. The vehicle of claim 34 or claim 35, wherein at least one wear resistant strip may comprise weld beads.

39. The vehicle of claim 38, wherein the weld beads are arranged in a substantially crisscross pattern.

40. The vehicle of any one of claims 34 to 39, wherein a join between the wear resistant strip surrounding the outer region of the end of the cylindrical portion and the wear resistant strip surrounding the outer region of an adjacent frustoconical portion is welded so as to protect the join.

41. The vehicle of any one of claims 10 to 40, wherein the drum has a length in the range of 3000mm to 7000mm.

42. The vehicle of any one of claims 10 to 41, wherein the cylindrical portion has a diameter in the range of

900mm to 1600mm.

43. The vehicle of any one of claims 10 to 42, wherein at least a portion of the drum comprises a friction reducing coating.

44. The vehicle of any one of claims 10 to 43, wherein the drum comprises stainless steel

45. A screw propelled vehicle comprising:

a chassis;

46. The vehicle of claim 45, wherein at least one drive assembly comprises a drive motor and a coupling assembly for coupling the drive motor to a respective drum, the coupling assembly comprising a bearing and sealing assembly and a drive shaft, the drive shaft being arranged to be received by the drive motor and the bearing and sealing assembly being arranged to substantially reduce, or prevent, ingress of the material into the interior of the drive assembly and/or an interior of the drums.

47. The vehicle of claim 46, wherein the bearing and sealing assembly comprises a bearing assembly for

receiving the drive shaft and a first seal assembly for sealing a junction between the drive shaft and the bearing assembly.

48. The vehicle of claim 47, wherein the first seal assembly comprises first and second bearing assembly seals and a sealing ring, the first bearing assembly seal being received in a recess in a surface of the drive shaft adjacent the junction, the second bearing assembly seal abutting the first bearing assembly seal and being received in a recess in a surface of the bearing assembly adjacent the junction, the sealing ring encircling the abutment between the first and second bearing seals and being received in further recesses in the adjacent surfaces of each of the drive shaft and the bearing assembly.

49. The vehicle of claim 47 or claim 48, wherein the bearing and sealing assembly comprises a second seal assembly for providing a seal between the bearing assembly and the drive motor.

50. The vehicle of claim 49, wherein the second seal assembly comprises a drive motor seal arranged between the bearing assembly and the drive motor.

51. The vehicle of claim 50, wherein an inner seal of the drive motor seal is retained against the bearing assembly by an inner seal retainer and an outer seal of the drive motor seal is retained against the drive motor by an outer seal retainer.

52. The vehicle of claim 51, wherein a drive motor seal adapter is provided between the outer seal and the drive motor and coupled to the drive motor so as to provide a means for indirectly coupling the outer seal to the drive motor.

53. The vehicle of claim 52, wherein the drive motor seal adapter comprise sealable holes, a cavity of the drive motor seal adapter being filled with grease via the holes prior to sealing the holes.

54. The vehicle of any one of claims 50 to 53, wherein the bearing and sealing assembly comprises a deflector assembly arranged so as to encircle the drive motor seal.

55. The vehicle of claim 54, wherein the deflector assembly comprises at least one aperture so as to

facilitate drainage and flushing of the deflector

assembly.

56. The vehicle of any one of claims 46 to 55, further comprising a seal fitted to the drive shaft at a region adjacent drive motor engaging teeth of the drive shaft.

57. The vehicle of claim 56, wherein the seal is fitted to the drive shaft prior to assembly of the drive motor onto the drive shaft.

58. The vehicle of any one of claims 46 to 57, wherein the drive shaft is formed from one piece.

59. The vehicle of any one of claims 45 to 58, wherein the coupling assembly is arranged so as to allow its respective drum to be filled and emptied with ballast.

60. The vehicle of claim 59, wherein the coupling assembly comprises a ballast inlet and outlet in fluid communication with an interior of the drum so as to allow the drum to be filled and emptied with ballast.