Tracked vehicle

Abstract

A tracked vehicle 1 is provided with a suspension assembly including a bogie member, a plurality of roller wheels rotatably mounted to the bogie member and engaging a track of the vehicle, and a suspe

Description

FIELD OF THE INVENTION The present invention relates to improvements in tracked land vehicles. The invention is particularly applicable to high-speed, scale or miniature tracked vehicles, for example tracked vehicles having a length of less than 2.5m and / or a weight of less than 150Kg and a track that is able to rotate at a rate of at least 90rpm during normal use of the vehicle. BACKGROUND OF THE INVENTION Tracked vehicles find uses in many applications due to their superior ability to operate on uneven, soft, lose or steep terrain compared to wheeled vehicles. Conventional tracked vehicles include a body with a track assembly located on either side thereof, each of which generally includes a continuous looped track, a drive wheel provided at the front or rear of the vehicle that is configured to drive the track, and a plurality of roller wheels that are configured to engage the inner surface of the lower portion of the track loop and support the weight of the vehicle. The track assemblies may further include a tensioner wheel at the end of the vehicle opposite to the drive wheel that is configured to maintain the desired level of tension in the track loop, and a plurality of idler wheels that are configured to engage the inner surface of the upper portion of the track loop between the drive wheel and the tensioner wheel in order to support and guide the upper portion of the track loop. Some tracked vehicles are further provided with suspension systems that are configured to allow the roller wheels to move in a vertical direction with respect to the body of the vehicle. In some tracked vehicles with suspension systems the roller wheels are movable independently of each other, while in other cases the roller wheels are mounted to bogies that are able to pivot about an internal axis as well as moving in a vertical direction with respect to the body of the vehicle. Tracked vehicles with suspension systems are generally able to operate better at high speeds and over uneven, soft or lose terrain due to the ability of the roller wheels and the track to conform to the contours of the ground that the vehicle is operated on. However, movement of the roller wheels relative to the body of the vehicle results in changes in track tension, which can make the tracks more likely to move out of their intended locations and become disengaged from the wheels of the track assembly in tracked vehicles with suspension systems, especially when operated at high speeds on uneven terrain. Tracked vehicles can be provided with various additional features for preventing the tracks from moving out of their intended locations and becoming disengaged from the wheels of the track assemblies. For example, the tracks may be provided with inwardly extending lugs or projections that are configured to be engaged by the various wheels of the track assemblies and the drive wheels may be provided with anti-throw flanges at their inner and / or outer edges in order to resist unwanted lateral movement of the tracks. However, it is still possible for the tracks to move out of their intended locations or even be thrown off the wheels in known tracked vehicles, especially when operated at high speeds. Scale tracked vehicles (that is track vehicles of reduced size that are generally too small to accommodate a human pilot) are becoming increasingly popular due to their ability to operate in locations that are difficult or hazardous for humans or larger, manned vehicles to operate in. The above-mentioned issues may be particularly pronounced in the case of high-speed, scale tracked vehicles. The present invention aims to address disadvantages of known tracked vehicles, particularly high-speed, scale tracked vehicles. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a tracked vehicle comprising a suspension assembly, the suspension assembly including: a bogie member; a plurality of roller wheels that are rotatably mounted to the bogie member and configured to engage a track of the vehicle; and a suspension mechanism that connects the bogie member to a body of the vehicle and is configured to allow the bogie member to move in a vertical direction with respect to the body of the vehicle, the suspension mechanism being configured to at least substantially prevent the bogie member from pivoting with respect to the body of the vehicle while the bogie member remains at a given height with respect to the body of the vehicle such that the bogie member remains at least substantially level with respect to the body of the vehicle. It will be appreciated that the “vertical” movement of the bogie member that is permitted by the suspension mechanism need not be pure vertical movement. For example, the bogie member may be mounted to the body of the vehicle by at least one swing arm and configured to move with respect to the body of the vehicle about the attachment point of the swing arm. The bogie member may therefore also move in a fore / aft direction with respect to the body of the vehicle as it moves in the vertical direction. In conventional tracked vehicles including suspension systems, the roller wheels are generally either movable independently of each other or are mounted to bogies that are able to pivot about an internal axis in order to maximise the ability of the roller wheels to conform to the contours of the ground that the vehicle is operated on. However, the applicant has discovered that mounting the roller wheels to bogie members that are prevented from pivoting about an internal axis with respect to the body of the vehicle at least while the bogie member remains at a given height with respect to the body of the vehicle can offer performance and reliability advantages, especially in the case of high-speed, scale or miniature tracked vehicles, in which the tracks are more likely to slip with respect to the roller wheels than in larger and / or lower speed tracked vehicles. In addition to at least substantially preventing the bogie member from pivoting with respect to the body of the vehicle while the bogie member remains at a given height with respect to the body of the vehicle, the suspension mechanism may further be configured to at least substantially prevent the bogie member from pivoting with respect to the body of the vehicle during vertical movement of the bogie member with respect to the body of the vehicle such that the bogie member continues to remain at least substantially level with respect to the body of the vehicle as it moves in the vertical direction with respect to the body of the vehicle. The tracked vehicle is preferably a high-speed tracked vehicle, for example a tracked vehicle including a track that is able to rotate at a rate of at least 90rpm during normal use of the vehicle, and / or a scale tracked vehicle, for example a tracked vehicle with a length less of less than 2.5m or less than 1,5m and / or a weight of less than 150kg or less than 100kg. The tracked vehicle may be an unmanned and / or remote-controlled tracked vehicle. The track may comprise a belt, which may form a continuous loop. The belt portion of the track may be generally flat and may have a low thickness compared to its width. The track may further comprise a plurality of drive teeth and / or a centering formation that extend inwardly from an inner surface of the belt. The centering formation may comprise a plurality of discrete centering projections arranged in a row that extends around the inner surface of the belt, and may be located towards a mid-point of the belt. The drive teeth may be provided in first and second rows that extend around the inner surface of the belt, and may be located towards the edges of the belt on opposite sides of the centering formation. The track may further comprise a plurality of treads that extend outwardly from an outer surface of the belt and are configured to engage the ground during use of the vehicle. The treads may comprise distal ends that collectively define an outer contact surface of the track. The track may be formed of an elastomeric material, for example natural rubber, may be formed as a single, integrally molded component, and may include reinforcement, for example in the form of or Kevlar fiber reinforcement. The track may be spaced apart from the body of the vehicle in a lateral direction by a distance that is at least 50% of the width of the track in order to provide space between the vehicle body and the track to accommodate the suspension assembly. It will be appreciated that the tracked vehicle may include a plurality of the suspension assemblies, preferably a plurality of the suspension assemblies on a first side thereof which are engaged with a first track and a plurality of the suspension assemblies on a second side thereof which are engaged with a second track. Any features described below in relation to “the suspension assembly” may apply equally to multiple suspension assemblies or to all of the suspension assemblies of the vehicle. The vehicle may comprise at least three suspension assemblies on a first side thereof which are engaged with a first track and at least three suspension assemblies on a second side thereof which are engaged with a second track. At least two of the suspension assemblies provided on each side of the vehicle may be suspension assemblies according to the present invention. For example, the vehicle may comprise three suspension assemblies on each side thereof, of which at least the middle and rear suspension assemblies may be suspension assemblies according to the present invention. The fact that the bogie members of at least some of the suspension assemblies are at least substantially prevented from pivoting with respect to the body of the vehicle reduces the ability of the roller wheels to conform to the contours of the ground that the vehicle is operated on. However, it has been found that by including at least three independently movable bogies on each side of the vehicle the roller wheels are still able to conform to the contours of the ground sufficiently well to allow the vehicle to operate reliably at high speeds and on uneven ground even if at least some of the bogie members are at least substantially prevented from pivoting with respect to the body of the vehicle. The suspension mechanism may comprise a linkage mechanism including a first linkage member and a second linkage member, the first linkage member being pivotally connected to the body of the vehicle at a first pivot point and pivotally connected to the bogie member at a second pivot point, and the second linkage member being pivotally connected to the body of the vehicle at a third pivot point and pivotally connected to the bogie member at a fourth pivot point. The first and third pivot points may be located at the same height as each other and the second and fourth pivot points may be located at the same height as each other with respect to the body of the vehicle. The distance between the first and third pivot points in a fore-aft direction of the vehicle may be equal to the distance between the second and fourth pivot points in the fore-aft direction of the vehicle. One of the first and second linkage members may be located outboard of the other one of the first and second linkage members with respect to the vehicle body, and the first and second linkage members may overlap with each other when viewed from the side of the vehicle. Arranging the linkage members in this manner allows a more compact arrangement for the suspension assembly and allows multiple suspension assemblies to be arranged closer together. The vehicle may have a front and a rear, and the first and second linkage members may be trailing arms that extend away from the first and third pivot points in a direction towards the rear of the vehicle. The first linkage member may have a kinked or curved shape that extends from a line extending through the first and second pivot points in a direction towards the second linkage member when viewed from the side of the vehicle, and the second linkage member may have a kinked or curved shape that extends from a line extending through the third and fourth pivot points in a direction towards the first linkage member when viewed from the side of the vehicle. Providing the first and / or second linkage members with kinked or curved shapes may facilitate a more compact design for the suspension assembly and allow multiple suspension assemblies to be arranged closer together. For example, providing a rearward trailing arm with a shape that is kinked or curved in a forward direction may provide additional clearance space for a shock absorber, and providing a forward trailing arm with a shape that is kinked or curved in a rearward direction may provide additional clearance space into which a further suspension assembly may be deflected in use, thereby allowing multiple suspension assemblies to be arranged closer together in a more compact arrangement. At least one of the first and second linkage members may comprise an aperture extending therethrough for accommodating a shock absorber that is connected to the body of the vehicle and to the suspension assembly. The suspension mechanism may comprise at least one linkage member connecting the bogie member to the body of the vehicle that is configured to be deflected in a lateral direction during cornering of the vehicle in order to absorb cornering forces. Where the suspension mechanism comprises first and second linkage members as described above the first and second linkage members may both be configured to be deflected in a lateral direction in order to enable the suspension mechanism to absorb cornering forces. The laterally deflectable linkage member may have a lateral stiffness of less than 20,000N / m or less than 15,000N / m for every Kg of total vehicle weight (for example a lateral stiffness of less than 200,000N / m or less than 150,000N / m in the case of a vehicle with a total weight of 10Kg), and may be configured to be deflected in a lateral direction by a distance of at least 2.5% of the distance between the point at which it is connected to the body of the vehicle and the point at which it is connected to the bogie member during normal use of the vehicle. The laterally deflectable linkage member may be formed with a thin, plate-like construction, may be formed of a plastics material and / or may include one or more cut-outs or regions of reduced thickness in order to reduce its lateral stiffness. The bogie member may be located inboard of the track at a location between the track and the body of the vehicle. Providing the bogie member at a location inboard to the track (instead of within the track loop) facilitates the use of larger wheels, bogie members and other suspension system components, and allows multiple suspension assemblies to be arranged closer together in a more compact arrangement. The bogie member may be provided with a track guide that extends downwardly therefrom, the track guide being configured to engage an inner side edge of the track in order to prevent the track from moving off the roller wheels in a direction towards the body of the vehicle. A downwardly extending track guide that is configured to engage the inner side edge of the track has been found to be more effective at preventing the track from being thrown off the roller wheels in a direction towards the body of the vehicle than existing track guide solutions, and is particularly effective when used in combination with a non-pivoting bogie arrangement as a non-pivoting bogie arrangement will maintain the track guide in the optimal position and angle for engaging the inner side edge of the track during use of the vehicle. The track guide may comprise a plate-like body that extends in a plane that is parallel to the inner side edge of the track and parallel to a longitudinal direction of the vehicle. A track guide of this type is able to maximise the possible contact area with the inner side edge of the track, thereby increasing the effectiveness of the track guide. The track guide may extend to a lower edge that is located below the outer surface of the belt of the track but above the distal ends of the treads of the track. The track guide may, for example, extend to a level that is at least 25%, at least 40% or approximately 50% of the distance between the outer surface of the belt and the distal ends of the treads. Arranging the track guide to extend to a level below the outer surface of the belt but above the distal ends of the treads enables the belt guide to engage the side edge of the belt while minimising engagement with the ground during use of the vehicle. The track guide may be formed as a separate component that is mounted to the bogie member, for example by one or more bolts. The track guide is preferably readily detachable from the bogie member in order to facilitate replacement of the track guide. However, in other embodiments the track guide may alternatively be integrally formed as a part of the bogie member. The track guide may be formed of a low friction material or provided with a low friction coating. The low friction material or coating may, for example, be nylon or PTFE. Forming the track guide using a low friction material or providing the track guide with a low friction coating may help to reduce friction between the track guide and the track and / or between the track guide and the ground during use of the vehicle. The bogie member may be provided with a center guide that extends outwardly therefrom, the center guide comprising at least one guide member that is configured to engage the centering formation that extends inwardly from the inner surface of the belt of the track in order to prevent the track from moving in a lateral direction with respect to the bogie member. A center guide that extends outwardly from the bogie member and includes at least one guide member that is configured to engage an inwardly extending centering formation of the track has been found to be particularly effective when used in combination with a non-pivoting bogie arrangement as a non pivoting bogie arrangement will maintain the center guide in the optimal position and angle for engaging the centering formation of the track during use of the vehicle. The center guide may comprise a first guide member located on a first side of the centering formation and a second guide member located on an opposed second side of the centering formation. Alternatively, the center guide may comprise a single guide member, which may be received between two centering formations that extend inwardly from the inner surface of the belt. The center guide may comprise a mounting portion that is connected to the bogie member and extends outwardly therefrom in a lateral direction, and the guide member(s) may extend downwardly from the mounting portion in a direction towards the belt of the track. The guide member(s) may be plate-like and may extend in plane(s) that are parallel to a longitudinal direction of the track and / or the vehicle. The or each guide member may comprise a leading edge and a trailing edge, and may taper in thickness towards its leading and / or trailing edges. The tapered leading and / or trailing edges of the guide member(s) may form lead in features that reduce the probability of the guide member catching on the centering formation of the track during use of the vehicle. The roller wheels of the suspension assembly may include at least one front roller wheel and at least one rear roller wheel, and the guide member(s) may be located between the front roller wheel and the rear roller wheel of the suspension assembly. The guide member(s) may have an approximately triangular shape when viewed from the side, and may include a leading edge with a shape that corresponds to the shape of the front roller wheel and a trailing edge with a shape that corresponds to the shape of the rear roller wheel in order to facilitate a more compact arrangement of the center guide and roller wheels. The center guide may be formed as a separate component that is mounted to the bogie member, for example by one or more bolts. The center guide is preferably readily detachable from the bogie member in order to facilitate replacement of the center guide. However, in other embodiments the center guide may alternatively be integrally formed as a part of the bogie member. The tracked vehicle may further comprise an anti-oscillation device that extends outwardly from the body of the vehicle, the anti-oscillation device being configured to engage an upper portion of the track in order to limit oscillation of the track. The provision of an anti-oscillation device that extends outwardly from the body of the vehicle and is configured to engage an upper portion of the track in order to limit oscillation of the track has been found to be particularly advantageous for high-speed tracked vehicles, especially high-speed, scale tracked vehicles. The anti-oscillation device may comprise a plate-like engagement member that is configured to engage the upper portion of the track. The engagement member may extend in a plane that is at least substantially parallel to the upper portion of the track. The engagement member preferably extends across at least a majority of the width of the track, for example across at least 75% or at least 90% of the width of the track. The engagement member preferably has a length (in a direction aligned with the length direction of the track) that is significantly greater than its width. However, it is not necessary for the engagement member to extend over the full length of the track as viewed from above the vehicle. For example, the engagement member may have a length that is at least 30% or at least 40% of the length of the track but less than 75% or less than 60% of the length of the track as viewed from above the vehicle. The engagement member may include upwardly angled sections at its leading and / or trailing ends in order to reduce the probability of the track catching on the ends of the engagement member. The tracked vehicle may further comprise a plurality of upper idler wheels that are configured to engage the inner surface of the upper portion of the track, and the centering formation (for example the centering projections) may be configured to be received in or between the upper idler wheels. The engagement member of the antioscillation device may extend above at least one and preferably a plurality of the upper idler wheels. The distance between the anti-oscillation device and the outer contact surface of the track may be less than the distance by which the centering formation extends from the inner surface of the belt, preferably less than 80% of the distance by which the centering formation extends from the inner surface of the belt. By arranging the anti-oscillation device sufficiently close to the belt that the distance between the anti-oscillation device and the outer contact surface of the track is less than the distance by which the centering formation extends from the inner surface of the belt, the anti-oscillation device and the idler wheels are able to prevent the track from becoming fully disengaged from and slipping off the upper idler wheels even if the belt oscillates up to the level of the anti-oscillation device. The tracked vehicle may further comprise a drive wheel that is engaged with and configured to drive the track. The drive wheel may be provided with a track realignment device that extends outwardly from an inner side of the drive wheel in a direction towards the body of the vehicle. The track realignment device may comprise a body having a diameter that increases in the direction extending away from the drive wheel towards the body of the vehicle in order to define a ramped outer engagement surface that is configured to be engaged by the track of the vehicle if the track moves from its intended position with respect to the drive wheel in a direction towards the body of the vehicle. The ramped engagement surface of the track realignment device is able to resist movement of the track off the drive wheel in a direction towards the body of the vehicle and effectively guide the track back towards its intended position with respect to the drive wheel, thereby preventing the track from slipping off the drive wheel and becoming jammed between the drive wheel and the body of the vehicle. In addition, the fact that the diameter of the track realignment device increases in a direction towards the body of the vehicle means that the effective track length will increase if the track continues to move further away from its intended position towards the body of the vehicle, thereby increasing the restoring force that is applied to the track by the track realignment device as it moves further away from its intended position. A track realignment device of this type has been found to be significantly more effective at preventing track throws compared to the anti-throw flanges found on conventional tracked vehicles, which can prevent a track from moving out of its intended position but generally become ineffective after the track has started to throw. This has been found to be particularly advantageous in the case of high-speed tracked vehicles. The track realignment device may be configured to rotate together with the drive wheel. The track realignment device may, for example, by rigidly connected to the drive wheel. In this case the track realignment device may be able to continue to drive the track even while the track is not fully engaged with the main body of the drive wheel. The track realignment device may be formed as a separate component that is mounted to the drive wheel, for example by one or more bolts. However, in other embodiments the track realignment device may alternatively be integrally formed together with the main body of the drive wheel. The outer engagement surface of the track realignment device may be convexly curved such that the rate of increase in the diameter of the track realignment device decreases in the direction towards the body of the vehicle. Arranging the track realignment device to have a pitch that is highest at the end closest to the drive wheel and decreases towards the body of the vehicle allows the track realignment device to have increased track realignment performance at its end closest to the drive wheel in order to resist movement of the track if it begins to move from its intended position towards the body of the vehicle while also allowing the track realignment device to extend further towards the body of the vehicle without having an excessively large diameter at its point of maximum diameter. The outer engagement surface of the track realignment device may be provided with a plurality of protrusions and / or recesses. The protrusions and / or recesses may increase the ability of the track realignment device to grip the track and guide it back towards the drive wheel. The protrusions and / or recesses may be spaced apart around the circumference of the track realignment device with a spacing that at least substantially matches the spacing of the drive teeth of the track. The track realignment device may increase in diameter towards a point of maximum diameter. The diameter of the track realignment device at the point of maximum diameter is preferably at least 10% greater than the diameter of the track realignment device at its end closest to the drive wheel and / or at least 10% greater than the diameter of a track engaging portion of the drive wheel. The point of maximum diameter of the track realignment device may be located at or adjacent to a distal end of the track realignment device located furthest from the drive wheel. The track realignment device preferably extends away from the inner side of the drive wheel towards the body of the vehicle by a distance that is at least 50% of the width of the track and / or at least 50% of the distance between the inner edge of the drive wheel and a side of the body of the vehicle. The outer engagement surface of the track realignment device may extend away from the drive wheel at an angle of more than 10 degrees but less than 45 degrees relative to an axis of rotation of the drive wheel and / or the track realignment device. According to a further aspect of the present invention there is provided a tracked vehicle comprising a suspension assembly including at least one roller wheel that is configured to engage a track of the vehicle, the roller wheel being connected to a body of the vehicle by a linkage mechanism including at least one linkage member, the linkage member being pivotally connected to the body of the vehicle and configured to enable the roller wheel to move in a vertical direction with respect to the body of the vehicle, wherein the linkage member is configured to be deflected in a lateral direction during cornering of the vehicle in order to absorb cornering forces. The roller wheel may be connected to the linkage member via a bogie member that is pivotally connected to a distal end of the linkage member. In this case the suspension assembly may include a plurality of roller wheels that are each rotatably mounted to the bogie member. However, in other embodiments the roller wheel may be rotatably mounted to the distal end of the linkage member without any bogie member being present. The linkage member may have a lateral stiffness of less than 20,000N / m or less than 15,000N / m for every Kg of total vehicle weight, and may be configured to be deflected in a lateral direction by a distance of at least 2.5% of the distance between the point at which it is connected to the body of the vehicle and the point at which it is connected to the roller wheel or bogie member during normal use of the vehicle. The linkage member may be formed of a plastics material and / or may include one or more cut-outs or regions of reduced thickness in order to reduce its lateral stiffness. The linkage member may be a trailing linkage member. In other words, the point at which the linkage member is pivotally connected to the body of the vehicle may be located in front of the point at which the linkage member is connected to the roller wheel or bogie member with respect to a forward direction of the vehicle. The linkage member may have a kinked or curved shape when viewed from the side that extends forward of a line extending through the point at which the linkage member is pivotally connected to the body of the vehicle and the point at which the linkage member is connected to the wheel or bogie member. Providing the linkage member with a shape that is kinked or curved in a forward direction may provide additional clearance space for a shock absorber, which may be connected between the body of the vehicle and the linkage member. Where the roller wheel is connected to the linkage member via a bogie member, the linkage mechanism may further comprise an additional linkage member that is pivotally connected to the body of the vehicle and pivotally connected to the bogie member, the additional linkage member being configured to at least substantially prevent the bogie member from pivoting about an internal axis with respect to the body of the vehicle. However, in other embodiments the linkage mechanism may only include a single linkage member. Where the linkage mechanism further comprises an additional linkage member that is configured to at least substantially prevent the bogie member from pivoting about an internal axis with respect to the body of the vehicle, the additional linkage member may be a secondary linkage member having a lateral stiffness that is significantly less than that of the primary linkage member, for example a stiffness that is less than 10% of that of the primary linkage member. In this case the additional linkage member may serve primarily to resist pivoting of the bogie member without contributing significantly to the lateral rigidity of the suspension assembly. The additional linkage member may, for example, have a thin, plate-like construction with a relatively low thickness in a direction aligned with the lateral direction of the vehicle. The vehicle may further comprise any one or more of the other features described above in connection with the first aspect of the present invention. According to a further aspect of the present invention there is provided a tracked vehicle comprising a track, the track including a belt and a centering formation (for example in the form of a plurality of discrete centering projections) that extends inwardly from an inner surface of the belt and is configured to be received in or between a plurality of upper idler wheels of the vehicle, wherein the vehicle further comprises an anti-oscillation device that extends outwardly from the body of the vehicle, the anti-oscillation device being configured to engage an upper portion of the track in order to limit oscillation of the track, wherein the distance between the antioscillation device and an outer contact surface of the track is less than the distance by which the centering formation extends from the inner surface of the belt, preferably less than 80% of the distance by which the centering formation extends from the inner surface of the belt. The anti-oscillation device may comprise a plate-like engagement member that is configured to engage the upper portion of the track. The engagement member may extend in a plane that is at least substantially parallel to the upper portion of the track. The engagement member may extend across at least a majority of the width of the track, for example across at least 75% or at least 90% of the width of the track. The engagement member may have a length (in a direction aligned with the length direction of the track) that is significantly greater than its width. The engagement member may, for example, have a length that is at least 30% or at least 40% of the length of the track but less than 75% or less than 60% of the length of the track as viewed from above the vehicle. The vehicle may further comprise any one or more of the other features described above in connection with the first aspect of the present invention. According to a further aspect of the present invention there is provided a tracked vehicle comprising a track, a drive wheel that is engaged with and configured to drive the track, and a track realignment device that extends outwardly from an inner side of the drive wheel in a direction towards the body of the vehicle, the track realignment device comprising a body having a diameter that increases in the direction extending away from the drive wheel towards the body of the vehicle in order to define a ramped outer engagement surface that is configured to be engaged by the track of the vehicle if the track moves from its intended position with respect to the drive wheel in a direction towards the body of the vehicle. The track realignment device may be configured to rotate together with the drive wheel. The track realignment device may, for example, by rigidly connected to the drive wheel. The track realignment device may be formed as a separate component that is mounted to the drive wheel, for example by one or more bolts. However, in other embodiments the track realignment device may alternatively be integrally formed together with the main body of the drive wheel. The outer engagement surface of the track realignment device may be convexly curved such that the rate of increase in the diameter of the track realignment device decreases in the direction towards the body of the vehicle. The outer engagement surface of the track realignment device may be provided with a plurality of protrusions and / or recesses. The protrusions and / or recesses may be spaced apart around the circumference of the track realignment device with a spacing that at least substantially matches the spacing of the drive teeth of the track. The track realignment device may increase in diameter towards a point of maximum diameter. The diameter of the track realignment device at the point of maximum diameter may be at least 10% greater than the diameter of the track realignment device at its end closest to the drive wheel and / or at least 10% greater than the diameter of a track engaging portion of the drive wheel. The point of maximum diameter of the track realignment device may be located at or adjacent to a distal end of the track realignment device located furthest from the drive wheel. The track realignment device may extend away from the inner side of the drive wheel towards the body of the vehicle by a distance that is at least 50% of the width of the track and / or at least 50% of the distance between the inner edge of the drive wheel and a side of the body of the vehicle. The outer engagement surface of the track realignment device may extend away from the drive wheel at an angle of more than 10 degrees but less than 45 degrees relative to an axis of rotation of the drive wheel and / or the track realignment device. The vehicle may further comprise any one or more of the other features described above in connection with the first aspect of the present invention. According to a further aspect of the present invention there is provided an asymmetric track for a tracked vehicle, the track having a first side or outer side and a second side or inner side. The first side or outer side may be configured to face outwardly away from a body of a vehicle to which the track may be mounted in use, and the second side or inner side may be configured to face inwardly towards the body of the vehicle. The track may comprise a belt and a plurality of asymmetric treads that extend outwardly from an outer surface of the belt. Each of the treads may extend in a width direction of the belt between a first end or outer end located towards the first side or outer side of the track and a second end or inner end located towards the second side or inner side of the track, and may have a height H in a direction extending away from the outer surface of the belt. Each of the treads may comprise a central portion and an outer portion that extends from the central portion of the tread to the outer end of the tread. The height H of each of the treads may decrease across the width W1 of the outer portion of the tread in a direction from the central portion towards the outer end of the tread in order to provide a region of reduced tread height towards the outer side of the track. The region of reduced tread height provided towards the outer side of the track may be greater than any region of reduced tread height provided in the tread towards the inner side of the track. In other words, the treads may each include a greater degree of tread height relief towards the outer side of the track than towards the inner side of the track. The asymmetric shape of the track with increased tread height relief towards the outer side of the track allows improved cornering performance. In particular, the increased corner relief at the outer ends of the treads reduces the tendency of the treads to catch on the ground during high-speed cornering maneuvers, reduces the moment acting to peel the track away from roller wheels of the vehicle during high-speed cornering maneuvers, and allows improved vehicle control while drifting. The increased corner relief at the outer ends of the treads may also allow the treads to maintain a higher contact area with the ground if the track and / or the vehicle to which the track is mounted begins to roll during high-speed cornering maneuvers. The width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread may be at least 25% or at least 40% of the total width W of the tread (between the outer and inner ends of the tread). The width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread may be at least 1.5 times greater than the height H of the tread at its highest point. The height H of the tread at its highest point may be at least equal to the thickness of the belt of the track. Each of the treads may further comprise an inner portion that extends from the central portion of the tread to the inner end of the tread. The height H of each of the treads may decrease across the width W2 of the inner portion of the tread in a direction from the central portion towards the inner end of the tread. The width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread may be greater than the width \N2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread, and is preferably at least twice the width W2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread. The width W2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread may be less than 20% of the total width W of the tread. In some embodiments that width \N2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread may be at least 10% of the total width W of the tread in order to provide a significant region of reduced tread height towards the inner side of the track (albeit a smaller region of reduced tread height than the region of reduced tread height provided towards the outer side of the track). However, the treads are not required to be provided with regions of reduced tread height towards their inner ends, and the inner ends of the treads may alternatively extend outwardly from the belt in a direction that is perpendicular to the outer surface of the belt. The height H of the tread at the interface between the central portion of the tread and the inner portion of the tread may be at least substantially equal to the height H of the tread at the interface between the central portion of the tread and the outer portion of the tread. The height H of the tread may be at least substantially constant across the width W3 of the central portion of the tread. The outer portion of the tread may have a distal end facing away from the belt of the track that is convexly curved when viewed from a direction aligned with a length direction of the track such that the rate of decrease in the height H of the tread across the outer portion of the tread increases in the direction from the central portion towards the outer end of the tread. Providing the outer portions of the treads with curved distal ends has been found to further reduce the tendency of the treads to catch on the ground and further reduce the moment acting to peel the track away from roller wheels of the vehicle during high-speed cornering maneuvers. The radius of curvature of the distal end of the outer portion of the tread may increase in the direction from the central portion towards the outer end of the tread. Each of the treads may comprise a discrete protrusion that extends continuously between the inner and outer ends of the tread. The treads may extend across the full width of the track between an inner side edge of the belt and an outer side edge of the belt. In this case the inner ends of the treads may be aligned with the inner side edge of the belt and the outer ends of the treads may be aligned with the outer side edge of the belt. Each of the treads may comprise a wall that extends outwardly from the outer surface of the belt in a direction substantially perpendicular to the outer surface of the belt. The treads may decrease in height H progressively across their inner portions to a height of approximately 0mm at their inner ends and / or decrease in height H progressively across their outer portions to a height of approximately 0mm at their outer ends. Each of the treads may have a thickness in a direction aligned with a length direction of the belt that tapers inwardly in a direction extending away from the belt. The belt portion of the track may be generally flat, and may have a low thickness compared to its width. The track may further comprise a plurality of drive teeth and / or a centering formation that extend inwardly from an inner surface of the belt. The centering formation may comprise a plurality of discrete centering projections arranged in a row that extends around the inner surface of the belt, and may be located towards a mid-point of the belt. The drive teeth may be provided in first and second rows that extend around the inner surface of the belt, and may be located towards the edges of the belt on opposite sides of the centering formation. The track may be formed of an elastomeric material, for example natural rubber, may be formed as a single, integrally molded component, and may include reinforcement, for example in the form of or Kevlar fiber reinforcement. According to a further aspect of the present invention there is provided a tracked vehicle comprising a body, a first track as described above mounted on a first side of the body of the vehicle, and a second track as described above mounted on an opposed second side of the body of the vehicle, wherein the inner side of each of the tracks faces inwardly towards the body of the vehicle and the outer side of each of the tracks faces outwardly away from the body of the vehicle. The tracked vehicle may be a high-speed tracked vehicle, for example a tracked vehicle including a track that is able to rotate at a rate of at least 90rpm during normal use of the vehicle, and / or a scale tracked vehicle, for example a tracked vehicle with a length less of less than 2.5m or less than 1,5m and / or a weight of less than 150kg or less than 100kg. The tracked vehicle may be an unmanned and / or remote-controlled tracked vehicle. The vehicle may further comprise any one or more of the other features described above in connection with the first aspect of the present invention. The above summary of invention refers to multiple different aspects of the present invention. It will be appreciated that features described in connection with each of the aspects of the invention may be combined with features described in connection with other aspects of the invention unless those features are incompatible with each other. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described by way of non-limiting example only and with reference to the accompanying drawings, in which: Figures 1a to 1d schematically illustrate side, top, front and rear views of a tracked vehicle in accordance with one possible embodiment of the present invention; Figure 2 schematically illustrates a suspension assembly of the vehicle; Figure 3 schematically illustrates a bogie member forming part of the suspension assembly; Figures 4a and 4b schematically illustrate the suspension assembly with the track, wheels and vehicle body omitted; Figures 5a and 5b schematically illustrate the suspension assembly as seen from the front and rear of the vehicle; Figures 6a and 6b schematically illustrate the suspension assembly in a lower position and a higher position with respect to the body of the vehicle; Figure 7 schematically illustrates the rear right corner of the vehicle as seen from behind the vehicle; Figure 8 schematically illustrates an upper portion of one of the track assemblies of the vehicle; Figures 9a and 9b schematically illustrate a drive wheel and track realignment device of the vehicle; Figures 10a and 10b schematically illustrate the drive wheel and track realignment device in isolation; Figure 11 schematically illustrates a side view of a section of the track of the vehicle, and Figure 12 schematically illustrates a cross-section view of the track taken in a plane transverse to a length direction of the track. DETAILED DESCRIPTION OF EMBODIMENTS Figures 1a to 1d schematically illustrate side, top, front and rear views of an unmanned, scale, high-speed, remote-controlled, tracked vehicle 1 in accordance with one possible embodiment of the present invention. The vehicle 1 has a length of approximately 1m and a weight of approximately 22Kg. As shown in Figures 1 a to 1 d, the vehicle 1 has a front 1a, a rear 1b, a left side 1c, a right side 1 d, a top 1e and a bottom 1f. The vehicle 1 has a longitudinal axis X which extends between the front 1 a and rear 1 b of the vehicle 1 and which is horizontal when the vehicle 1 is unloaded and on flat, level ground. The vehicle 1 also has a transverse axis Y which extends between the left and right sides 1c, 1d of the vehicle 1 in a direction perpendicular to the longitudinal axis X. The vehicle 1 also has a vertical axis Z which extends between the top 1e and bottom 1f of the vehicle in a direction perpendicular to the longitudinal axis X and the transverse axis Y. The vehicle 1 comprises a body 2 and a pair of track assemblies 3 arranged on opposite sides of the body 2. The track assemblies 3 include a left side track assembly 3a on the left side 1c of the vehicle 1 and a right side track assembly 3b on the right side 1 d of the vehicle 1. The following description refers to a single track assembly 3. However, it will be appreciated that the left and right side track assemblies 3a, 3b have similar arrangements to each other, and that the features described below apply to both the left and right side track assemblies 3a, 3b. The track assembly 3 comprises a continuous, looped, ground-engaging track 4. The track 4 extends in a plane that is parallel to the longitudinal axis X of the vehicle, and has an outer side 4a that faces outwardly away from the body 2 of the vehicle 1 and an inner side 4b that faces inwardly towards the body 2 of the vehicle 1. As shown most clearly in Figures 1a, 11 and 12, the track 4 comprises a belt portion 5 which extends continuously around the length of the track 4 to form the looped shape of the track 4. The belt 5 of the track 4 extends between an outer side edge 5a on the outer side 4a of the track 4 and an inner side edge 5b on the inner side 4b of the track 4, is generally flat, and has a comparatively low thickness relative to its width. The track 4 further comprises a series of drive teeth 7 and a centering formation formed by a series of centering projections 6 that extend inwardly from an inner surface 5” of the belt 5 around the length of the track 4. The centering projections 6 are arranged in a single row that extends around the length of the track 4 at a location towards the mid-point of the belt 5 (half way between the side edges 5a, 5b of the belt 5), and the drive teeth 7 are arranged in two rows that extend around the length of the track 4 towards the side edges 5a, 5b of the belt 5 on opposing sides of the row of centering projections 6. The centering projections 6 and the drive teeth 7 each have a tapered shape that tapers inwardly in a direction extending away from the belt 5 of the track 4 when viewed from the side of the track 4. The centering projections 6 are significantly taller than the drive teeth 7, extending to a height that is several times greater than the height of the drive teeth 7. The track further comprises a plurality of treads 8 that extend outwardly from an outer surface 5’ of the belt 5 around the length of the track 4 and are configured to engage the ground during use of the vehicle 1. Each of the treads 8 comprises a discrete, wall-like projection that extends in a direction substantially perpendicular to the outer surface 5’ of the belt 5 of the track 4 between the side edges 5a, 5b of the belt 5. As shown most clearly in Figure 11, each of the treads 8 has a thickness (in a direction aligned with a length direction of the belt 5) that is smaller than its width (in a direction extending across the width of the belt 5) and its height (in a direction extending away from the outer surface 5’ of the belt 5), and that tapers inwardly in a direction extending away from the belt 5. As also shown in Figure 11, the spacing between the treads 8 along the length direction of the track 4 is twice that of the centering projections 6 and drive teeth 7, and one of the treads 8 is aligned with every second centering projection 6 and pair of drive teeth 7 along the length of the track 4. The treads 8 terminate in distal ends that face away from the belt 5 of the track 4, the distal ends of the treads 8 collectively defining an outer contact surface 9 of the track 4. Figures 1a to 1d illustrate the treads 8 as having a simple shape that is symmetrical about a centre line of the track 4. However, the treads 8 may alternatively have an asymmetric shape as described in more detail below with reference to Figure 12. The track 4 is formed as a single, integrally moulded component, is made of an elastomeric material, for example a natural rubber such as RSS3 Natural Rubber Latex, and includes Kevlar fiber reinforcement. As shown in Figures 1b, 1c and 1 d, the track is spaced apart from the side of the body 2 of the vehicle 1 by a distance that is approximately equal to the width of the track 4 in order to provide space to accommodate a suspension system which is described in more detail below. As shown most clearly in Figure 1a, the track assembly 3 further comprises a plurality of roller wheels 10 that are configured to engage the inner surface of the lower portion of the track 4 and support the weight of the vehicle 1, a drive wheel 11 that is configured to drive the track 4 in a forward or rearward direction, a tensioner wheel 12 that is configured to maintain the desired level of tension in the track 4, and a plurality of upper idler wheels 13 that are configured to engage the inner surface of the upper portion of the track 4 between the drive wheel 11 and the tensioner wheel 12 in order to support and guide the upper portion of the track 4. The roller wheels 10 are mounted to the body 2 of the vehicle 1 by a plurality of suspension assemblies 20 including a front suspension assembly, a middle suspension assembly, and a rear suspension assembly, each of which has two of the roller wheels 10 mounted thereto. One of the suspension assemblies 20 is illustrated in Figures 2 to 6b. Figure 2 illustrates the suspension assembly 20 connected to the body 2 of the vehicle 1. The adjacent suspension assemblies 20, the upper idler wheels 13 and the majority of the track 4 have been omitted from this drawing for clarity. Figure 3 illustrates a bogie member of the suspension assembly 20 in isolation. Figures 4a and 4b illustrate the suspension assembly 20 as seen from the side and from above in isolation from the body 2 of the vehicle 1 with the roller wheels 10 removed. Figures 5a and 5b illustrate the suspension assembly 20 as seen from the front and from the rear of the vehicle 1. Figures 6a and 6b illustrate the suspension assembly 20 in lower and higher positions with respect to the body 2 of the vehicle 1. As shown in Figures 2 to 6b, each of the suspension assemblies 20 comprises a bogie member 21 and a suspension mechanism 22 that connects the bogie member 21 to the body 2 of the vehicle 1. Each of the bogie members 21 is a generally planar, platelike component that extends in a vertical plane parallel to the longitudinal axis X of the vehicle 1. Each of the bogie members 21 includes three shafts 21a, 21b, 21c that extend outwardly therefrom, including a first shaft 21a that extends in a direction away from the body 2 of the vehicle 1 towards a front of the bogie member 21, a second shaft 21b that extends in the direction away from the body 2 of the vehicle 1 towards a rear of the bogie member 21, and a third shaft 21 c that extends in a direction towards the body 2 of the vehicle 1 at an intermediate location between the first and second shafts 21a, 21b. The first, second and third shafts 21a, 21b, 21c are all arranged at the same height as each other with respect to the bogie member 21 and the body 2 of the vehicle 1. A first one of the roller wheels 10 is rotatably mounted to the first shaft 21a and a second one of the roller wheels 10 is rotatably mounted to the second shaft 21 b. The roller wheels 10 are therefore located outboard of the bogie member 21 with respect to the body 2 of the vehicle, and are located at the same height as each other when the bogie member 21 is in a level configuration. As shown in Figures 2, 5a and 5b, each of the roller wheels 10 includes a first wheel portion 10a and a second wheel portion 10b that is connected to the first wheel portion 10a by a connecting portion 10c (although in other embodiments the first and second wheel portions 10a, 10b may be provided independently of each other, in which case the connecting portion 10c may be omitted). The connecting portion 10c has a reduced diameter compared to the first and second wheel portions 10a, 10b such that the first and second wheel portions 10a, 10b are spaced apart from each other in a direction aligned with a rotational axis of the roller wheel 10 by an annular gap 10d. As shown most clearly in Figures 5a and 5b, the first and second wheel sections 10a, 10b of each roller wheel 10 are configured to engage the inner surface of the belt 5 of the track 4 on opposing sides of the row of centering projections 6 (between the row of centering projections 6 and the rows of drive teeth 7) in order to transfer the weight of the vehicle 1 to the track 4, with the centering projections 6 being accommodated in the annular gap 10d as the belt 4 runs over the roller wheel 10. As shown most clearly in Figure 2, the suspension mechanism 22 of each of the suspension assemblies 20 comprises a first linkage member in the form of a trailing arm 23 which is pivotally connected to the body 2 of the vehicle 1 at a first end thereof and to the bogie member 21 of the suspension assembly 20 at a second end thereof. In particular, each of the trailing arms 23 comprises a first aperture at a proximal end thereof which is mounted to a shaft that extends outwardly from the body 2 of the vehicle 1 in order to pivotally connect the trailing arm 23 to the body 2 of the vehicle 1 at a first pivot point 23a, and a second aperture at a distal end thereof which is mounted to the third shaft 21 c of a respective one of the bogie members 21 in order to pivotally connect the trailing arm 23 to the bogie member 21 at a second pivot point 23b. Each of the trailing arms 23 is also connected to the body 2 of the vehicle 1 by a shock absorber 25 including a spring and a damper, which extends downwardly from the body 2 of the vehicle 1 and has a distal end that is received within an aperture 23c provided in the trailing arm 23 and secured to the trailing arm 23 by a mounting pin that extends across the aperture 23c. Each of the trailing arms 23 has a curved or kinked shape when viewed from the side of the vehicle 1 that extends forward of a line extending between its first and second pivot points 23a, 23b, which provides additional clearance space for the shock absorber 25, thereby facilitating a more compact design for the suspension mechanism 22 and the use of a larger shock absorber 25. Each of the trailing arms 23 is formed of Nylon 6, and is provided with a pair of cutouts in order to reduce its lateral stiffness. In particular, each of the trailing arms 23 is provided with a first cut-out in its upwardly / rearwardly facing edge that extends in a lateral direction through the thickness of the trailing arm 23, and a second cut-out that extends in a longitudinal direction of the trailing arm 23 around its upwardly / rearwardly facing edge, its downwardly / forwardly facing edge and both of its ends. The use of a plastics material to form the trailing arms 23 and the presence of the above-mentioned cut-outs result in the trailing arms 23 having a comparatively low lateral stiffness of approximately 240,000N / m, which allows the trailing arms 23 to deflect in a lateral direction by at least 2.5% of the distance between their first and second pivot points 23a, 23b during normal use of the vehicle 1. In this way the trailing arms 23 are able absorb cornering forces, thereby improving the high-speed cornering performance of the vehicle 1. As also shown in Figure 2, the suspension mechanisms 22 of the middle and rear suspension assemblies 20 further include a second linkage member in the form of a trailing anti-rotation arm 24, which is also pivotally connected to the body 2 of the vehicle 1 at a first end thereof and to the bogie member 21 of the suspension assembly 20 at a second end thereof. In particular, each of the anti-rotation arms 24 comprises a third aperture at a proximal end thereof which is mounted to a further shaft that extends outwardly from the body 2 of the vehicle 1 in order to pivotally connect the anti-rotation arm 24 to the body 2 of the vehicle 1 at a third pivot point 24a, and a fourth aperture at a distal end thereof which is mounted to the first shaft 21 a of a respective one of the bogie members 21 in order to pivotally connect the anti-rotation arm 24 to the bogie member 21 at a fourth pivot point 24b. For each of the middle and rear suspension assemblies 20, the third pivot point 24a (at which the anti-rotation arm 24 is pivotally connected to the body 2 of the vehicle 1) is located forward of and at the same height as the first pivot point 23a (at which the trailing arm 23 is pivotally connected to the body 2 of the vehicle 1), and the fourth pivot point 24b (at which the anti-rotation arm 24 is pivotally connected to the bogie member 21) is located forward of and at the same height as the second pivot point 23b (at which the trailing arm 23 is pivotally connected to the bogie member 21). In addition, distance between the first and third pivot points 23a, 24a in the fore-aft direction of the vehicle 1 is equal to the distance between the second and fourth pivot points 23b, 24b in the fore-aft direction of the vehicle 1. Each of the anti-rotation arms 24 has a bent shape that extends around the outside of the trailing arm 23 of its respective suspension assembly 20. This allows the antirotation arms 24 to overlap with the trailing arms 23 along a portion of their lengths, thereby facilitating a more compact arrangement of the suspension assemblies 20 in a fore-aft direction of the vehicle 1. Each of the anti-rotation arms 24 also has a curved or kinked shape when viewed from the side of the vehicle 1 that extends rearward of a line extending between its third and fourth pivot points 24a, 24b, which provides additional clearance space into which another one of the suspension assemblies 20 may be deflected in use, thereby allowing the suspension assemblies 20 to be arranged closer together in a more compact arrangement. Each of the anti-rotation arms 24 is formed of an aluminium alloy and has a thin, platelike construction with a relatively low thickness in a direction aligned with the transverse axis Y of the vehicle 1. The low thickness of the anti-rotation arms 24 results in the anti-rotation arms 24 having a very low lateral stiffness of approximately 20,000N / m. The anti-rotation arms 24 therefore do not contribute significantly to the lateral stiffness of the middle and rear suspension assemblies 20. However, the antirotation arms 24 have a significantly higher stiffness in the vertical and fore-aft directions of the vehicle 1, and form four-bar type linkage mechanisms together with the trailing arms 23 that allow the bogie members 21 of the middle and rear suspension assemblies 20 to move in a vertical direction with respect to the body 2 of the vehicle 1 when the suspension assemblies 20 are compressed, as shown in Figures 6a and 6b, but prevent the bogie members 21 of the middle and rear suspension assemblies 20 from pivoting about an internal axis during vertical movement with respect to the body 2 of the vehicle 1. The trailing arms 23 and anti-rotation arms 24 therefore keep the middle and rear bogie members 21 in a level orientation (at a constant angle with respect to the longitudinal axis X of the vehicle 1) and keep the roller wheels 10 that are mounted to the each of the middle and rear bogie members 21 at the same height as each other with respect to the body 2 of the vehicle 1 as the middle and rear bogie members 21 move with respect to the body 2 of the vehicle 1. As shown most clearly in Figures 2 and 7, each of the bogie members 21 is located inboard of the track 4 at a location between the track 4 and the body 2 of the vehicle 1 in order to facilitate the use of larger roller wheels 10, bogie members 21 and other suspension system components. Each bogie member 21 is also provided with a planar or plate-like track guide 30 that extends downwardly therefrom in a direction towards the ground in a plane that is parallel to the inner side 4b of the track 4 and to the longitudinal axis X of the vehicle 1. The track guide 30 extends downwardly from the bogie member 21 to a level below the outer surface 5’ of the belt 5 of the track 4. In particular, the track guide 30 extends to a lower edge 31 that is located approximately 40% of the distance between the outer surface 5’ of the belt 5 of the track 4 and the distal ends of the treads 8 of the track 4. The track guide 30 has a planar contact face 32 that is configured to engage the inner side 4b of the track 4 in order to prevent the track 4 from moving off the roller wheels 10 in a direction towards the body 2 of the vehicle 1. The track guide 30 tapers inwardly in thickness in a direction towards its lower edge 31, and has front and rear lower corners that are curved or chamfered in order to reduce the tendence of the track guide 30 to catch on the ground during use of the vehicle 1. The track guide 30 is formed of nylon or PTFE in order to minimise friction between the track guide 30 and the track 4 and between the track guide 30 and the ground during use of the vehicle 1, and is attached to the bogie member 21 by a plurality of bolts in order to be readily detachable therefrom to facilitate removal and replacement of the track guide 30. The fact that the bogie members 21 of the middle and rear suspension assemblies 20 are prevented from pivoting about an internal axis relative to the body 2 of the vehicle 1 when their suspension assemblies 20 are compressed enables the track guides 30 to function particularly effectively because the bogie members 21 are able to maintain their track guides 30 in the optimal position and angle for engaging the inner side 4b of the track 4 during use of the vehicle 1. As shown most clearly in Figures 2, 3, 6a and 6b, each bogie member 21 is also provided with a center guide 40 that is configured to engage the centering projections 6 of the belt 4 in order to prevent the track 4 from moving in a lateral direction with respect to the bogie member 21. The center guide 40 is mounted to the bogie member 21 by a mounting portion 41, which is removably connected to the bogie member 21 towards an upper edge thereof by a plurality of bolts. The mounting portion 41 takes the form of an elongate arm that extends outwardly from the bogie member 21 in a lateral direction away from the body 2 of the vehicle 1, and then curves downwardly in a direction towards the lower portion of the track 4. The center guide 40 further comprises a pair of guide members 42 which are integrally formed with the mounting portion 41 end extend downwardly from a distal end thereof in a direction towards the lower portion of the track 4 at a location between the front and rear roller wheels 10 of the bogie member 21. The guide members 42 are plate-like in form and extend in planes that are parallel to the length direction of the track 4 and to the longitudinal axis X of the vehicle 1. The guide members 42 increase in width (in a direction aligned with the length direction of the track 4 and the longitudinal axis X of the vehicle 1) in a direction towards the track 4 in a substantially triangular shape, and each have a flat distal end that extends parallel to belt 5 of the track 4 a small distance away from the inner surface of the belt 5 of the track 4. The leading and trailing edges of the guide members 42 substantially correspond to the shapes of the front and rear roller wheels 10 when viewed from the side in order to facilitate a more compact arrangement of the center guide 40 and roller wheels 10. The guide members 42 are spaced apart from each other in a lateral direction of the vehicle 1 in order to form a gap 43 therebetween that is sized to receive the centering projections 6 of the track 4. During use of the vehicle 1, the centering projections 6 of the track 4 pass between the guide members 42 as the track 4 moves past the bogie member 21, and the guide members 42 are able to engage the side edges of the centering projections 6 in order to prevent the track 4 from moving in a lateral direction with respect to the bogie member 21. The guide members 42 also taper in thickness towards their leading and trailing edges in order to reduce the probability of the guide members 42 catching on the centering projections 6. The fact that the bogie members 21 of the middle and rear suspension assemblies 20 are prevented from pivoting about an internal axis relative to the body 2 of the vehicle 1 when their suspension assemblies 20 are compressed enables the center guides 40 to function particularly effectively because the bogie members 21 are able to maintain their center guides 40 in the optimal position and angle for engaging the centering projections 6 of the track 4 during use of the vehicle 1. As shown in Figures 1, 7, 9a and 9b, the drive wheel 11 is rotatably mounted to the body 2 the vehicle 1 at a location towards the rear 1 b of the vehicle 1. The drive wheel 11 is connected via a gearbox (not shown) to a motor (not shown) located inside the body 2 of the vehicle 1 that is configured to rotate the drive wheel 10 in a forward or rearward direction. The motor is powered by a battery (not shown) located inside the body 2 of the vehicle 1 that is configured to supply power to the motor. The drive wheel 10 is capable of driving the track at speeds of up to 812rpm (track revolutions per minute). As shown in Figures 10a and 10b, the drive wheel 11 comprises a cylindrical body that is formed by first and second drum sections 11a, 11b. The first drum section 11a forms a first end of the cylindrical body located towards the body 2 of the vehicle 1 and the second drum section 11b forms an opposing second end of the cylindrical body located away from the body 2 of the vehicle 1. The first and second drum sections 11a, 11 b are connected together by a central connecting portion 11 c, and each include an end plate 11 d and a series of protrusions 11e in a circular arrangement that extend outwardly from the end plate 11d in a direction towards the other drum section 11a, 11 b in order to define an outer surface of the cylindrical body. The protrusions 11e on each of the first and second drum sections 11a, 11b are spaced apart from each other by a series of recesses 11f. The recesses 11f formed between the drive teeth 11 e are configured to receive the drive teeth 7 of the belt 4 therein as the drive wheel 11 and belt 4 rotate in order to prevent the belt 4 from slipping with respect to the drive wheel 11 and maximise the efficiency of the transmission of drive power from the drive wheel 11 to the belt 4. The protrusions 11 e of the first and second drum sections 11a, 11 b are spaced apart from each other by a gap 11g that is sufficiently wide to enable the centering projections 6 to pass therethrough as the belt 4 runs over the drive wheel 11 during use of the vehicle 1. The protrusions 11e are located slightly inboard of the outer edges of the end plates 11 d of the drive wheel 11. The end plates 11 d therefore each define a small retaining flange that extends outboard of the protrusions 11 e and is configured to engage one of the side edges 5a, 5b of the belt 5 of the track 4 in order to resist lateral movement of the track 4 with respect to the drive wheel 11. As shown in Figures 7, 9a, 9b, 10a and 10b, the drive wheel 11 is also provided with a track realignment device 50 that is mounted to the end plate 11 d of the first drum section 11a and extends away from the inner end of the drive wheel 11 in a direction towards the body 2 of the vehicle 1. The track realignment device 50 shares an axis of rotation with the drive wheel 11, and is configured to rotate together with the drive wheel 11 during use of the vehicle 1. The track realignment device 50 comprises a base wall 51 with a plurality of apertures 52 extending therethrough that are configured to receive a corresponding plurality of bolts in order to rigidly connect the track realignment device 50 to the drive wheel 11, and an annular wall 53 that extends outwardly from the base wall 51 around the perimeter thereof in a direction towards the body 2 of the vehicle 1. The annular wall 53 defines a main body of the track realignment device 50 and has an outer engagement surface 54 that is configured to be engaged by the track 4 if the track 4 moves out of its intended position with respect to the drive wheel 11 in a direction towards the body 2 of the vehicle 1. The annular wall 53 is angled outwardly away from the axis of rotation of the drive wheel 11 and track realignment device 50 in a direction extending away from the drive wheel 11 towards the body 2 of the vehicle 1 such that the width or diameter of the track realignment device 50 and its outer engagement surface 54 increase progressively in a direction towards the body 2 of the vehicle 1. The outer engagement surface 54 of the track realignment device 50 is also convexly curved, as best shown in Figures 9b and 10b, such that the rate of increase in the diameter of the track realignment device 50 and its outer engagement surface 54 decreases in a direction towards the body 2 of the vehicle 1. The track realignment device 50 extends away from the inner side of the drive wheel 11 towards the body 2 of the vehicle 1 by a distance that is approximately 75% of the width of the track 4 and approximately 75% of the distance between the inner side of the drive wheel 11 and the side of the body 2 of the vehicle 1. The track realignment device 50 increases in diameter by approximately 12% from its proximal end (adjacent to the drive wheel 11) to a point of maximum diameter located at or adjacent to its distal end (furthest from the drive wheel 11), and the diameter of the track realignment device 50 at its point of maximum diameter is approximately 16% greater than the diameter of the track engaging portion of the drive wheel 11 as defined by the outer surfaces of the protrusions 11 e. The ramped engagement surface 54 of the track realignment device 50 acts to guide the track 4 back towards the drive wheel 11 if it starts to move away from its intended position with respect to the drive wheel 11 in a direction towards the body 2 of the vehicle 1, and applies a restoring force that increases progressively if the track 4 continues to move further away from its intended position towards the body 2 of the vehicle 1. The track realignment device 50 is illustrated as having a smooth outer engagement surface 54 in Figures 7, 9a, 9b, 10a and 10b. However, in other embodiments the outer engagement surface 54 of the track realignment device 50 may be provided with a plurality of protrusions and / or recesses which may be spaced apart around the circumference of the track realignment device 50 with a spacing that at least substantially matches the spacing of the drive teeth 7 of the track 4 in order to increase the ability of the track realignment device 50 to grip the track 4 and guide it back towards the drive wheel 11. As shown in Figure 1a, the tensioner wheel 12 is rotatably mounted to a platform 12a that is mounted to the body 2 of the vehicle 1 by a biasing mechanism 12b at a location towards the front 1a of the vehicle 1. The biasing mechanism 12b is configured to bias the tensioner wheel 12 in an outward direction into engagement with the inner surface of the track 4 in order to maintain the desired level of tension in the track 4 as the suspension assemblies 20 move with respect to the body 2 of the vehicle 1. As also shown in Figure 1a, the upper idler wheels 13 are rotatably mounted to the body 2 of the vehicle 1 in a row that extends in a direction between the drive wheel 11 and the tensioner wheel 12. As shown in Figure 8, each of the upper idler wheels 13 comprises a first wheel portion 13a and a second wheel portion 13b that is connected to the first wheel portion 13a by a connecting portion 13c (although in other embodiments the first and second wheel portions 13a, 13b may be provided independently of each other, in which case the connecting portion 13c may be omitted). The connecting portion 13c has a reduced diameter compared to the first and second wheel portions 13a, 13b such that the first and second wheel portions 13a, 13b are spaced apart from each other in a direction aligned with a rotational axis of the idler wheel 13 by an annular gap 13d. The first and second wheel sections 13a, 13b are configured to engage the inner surface of the belt 5 of the track 4 on opposing sides of the row of centering projections 6 (between the row of centering projections 6 and the rows of drive teeth 7) in order to support and guide the upper portion of the track 4 between the drive wheel 11 and the tensioner wheel 12 and the annular gap 13d is configured to receive the centering projections 6 therein as the belt 4 moves over the idler wheel 13. As shown most clearly in Figure 8, the vehicle 1 further comprises a pair of antioscillation devices 60 that extend outwardly from the sides of the body 2 of the vehicle 1 above the tracks 4 on either side of the vehicle 1. Each each of the anti-oscillation devices 60 comprises a mounting portion 61 that is connected to the body 2 of the vehicle by a plurality of bolts, and a plate-like engagement member 62 that extends outwardly from the mounting portion 61 in a direction away from the body 2 of the vehicle 1. Each engagement member 62 extends in a plane that is substantially parallel to the upper portion of the track 4 over which it is located, extends across the majority of the width of the track 4, has a length (in a direction aligned with the length direction of the track 4) that is approximately 45% of the length of the track 4 as viewed from above the vehicle 1, and extends directly above a plurality of the upper idler wheels 13. The engagement members 62 each include upwardly angled sections at their leading and trailing ends in order to reduce the probability of the track 4 catching on the ends of the engagement members 62 as the track 4 moves over the upper idler wheels 13. Each of the anti-oscillation devices 60 is arranged sufficiently close to the track 4 over which it is located that the distance between the lower surface of the engagement member 62 and the outer ends of the treads 8 of the track 4 is no more than 80% of the distance by which the centering projections 6 extend from the inner surface of the belt 5 of the track 4. The engagement members 62 of the anti-oscillation devices 60 are configured to engage the upper portions of the tracks 4 if the tracks 4 begin to oscillate during use of the vehicle 1 in order to limit the amplitude of oscillations. As the distance between the lower surface of the engagement member 62 and the outer ends of the treads 8 of the track 4 is less than the distance by which the centering projections 6 extend from the inner surface of the belt 5 of the track 4, the centering projections 6 will still be retained between the first and second wheel portions 13a, 13b of the upper idler wheels 13 even if the track 4 oscillates up to the level of the engagement members 62 of the anti-oscillation devices 60, thereby preventing the upper portion of the track 4 from becoming fully disengaged from and slipping off the upper idler wheels 13. As mentioned above, the tracks 4 of the vehicle 1 may include treads 8 with an asymmetric shape as illustrated in Figure 12. The following description refers to a single track 4. However, the features described below apply equally to each of the left and right side tracks 4, which are mirror images of each other. As shown in Figure 12, each of the treads 8 extends outwardly from the outer surface 5’ of the belt 5 of the track 4 across the width of the track 4 between an outer end 8a which is aligned with the outer side edge 5a of the belt 5 on the outer side 4a of the track 4 and an inner end 8b which is aligned with the inner side edge 5b of the belt 5 on the inner side 4b of the track 4. Each tread 8 includes a central portion 8c provided towards the middle of the track 4, an outer portion 8d that extends from a first side of the central portion 8c to the outer end 8a of the tread 8, and an inner portion 8e that extends from an opposed second side of the central portion 8c to the inner end 8b of the tread 8. Each tread 8 has a height H in a direction extending away from the outer surface 5’ of the belt 5 of the track 4 which is greatest in the central portion 8c of the tread 8. The height of each tread 8 is approximately constant across the width W3 of the central portion 8c of the tread 8. However, the height H of each tread 8 decreases progressively across the width W1 of the outer portion 8d of the tread 8 in a direction from the central portion 8c towards the outer end 8a of the tread 8 in order to provide a region of reduced tread height towards the outer side 4a of the track 4. The height H of each tread 8 also decreases progressively across the width W2 of the inner portion 8e of the tread 8 in a direction from the central portion 8c towards the inner end 8b of the tread 8 in order to provide a region of reduced tread height towards the inner side 4b of the track 4. However, the width W1 of the outer portion 8d of the tread 8 over which the height H of the tread 8 decreases towards the outer end 8a of the tread 8 is significantly greater than the width W2 of the inner portion 8e of the tread 8 over which the height H of the tread 8 decreases towards the inner end 8b of the tread 8. The treads 8 therefore have larger regions of reduced tread height towards the outer side 4a of the track 4 (which faces outwardly away from the body 2 of the vehicle 1) than towards the inner side 4b of the track 4 (which faces inwardly towards the body 2 of the vehicle 1). This has been found to allow improved cornering performance, in particular by reducing the tendency of the treads 8 to catch on the ground and by reducing the moment acting to peel the track 4 away from the roller wheels 10 during high-speed cornering maneuvers. In the present embodiment the width W1 of the outer portion 8d of each tread 8 over which the height H of the tread 8 decreases towards the outer end 8a of the tread 8 is approximately 50% of the total width W of the tread 8 and approximately 3 times greater than the width W2 of the inner portion 8e over which the height H of the tread 8 decreases towards the inner end 8b of the tread 8. In addition, the width W1 of the outer portion 8d of each tread 8 over which the height H of the tread 8 decreases towards the outer end 8a of the tread 8 is approximately 2.25 times greater than the height H of the tread 8 at its highest point, which is itself approximately 2 times greater than the thickness t of the belt 5 of the track 4. However, it will be appreciated that other values may be used in other embodiments. In addition, in other embodiments the treads 8 may not include regions of reduced tread height towards their inner ends 8b, in which case the inner ends 8b of the treads 8 may extend outwardly from the belt 5 of the track 4 in a direction that is perpendicular to the outer surface 5’ of the belt 5. The outer portion 8d of each of the treads 8 has a distal end 8f facing away from the belt 5 of the track 4 that is convexly curved when viewed from a direction aligned with the length direction of the track 4 (as in Figure 12) such that the rate of decrease in the height H of the tread 8 across the outer portion 8d of the tread 8 increases in the direction from the central portion 8c towards the outer end 8a of the tread 8. The radius of curvature of the distal end 8f of the outer portion 8d also increases in the direction from the central portion 8c towards the outer end 8a of the tread 8. This configuration has been found to further reduce the tendency of the treads 8 to catch on the ground and further reduce the moment acting to peel the track 4 away from roller wheels 10 during high-speed cornering maneuvers. It will be appreciated that many modifications may be made to the above-described embodiment(s) without departing from the scope of the present invention as defined in the appended claims. This specification defines the positions and orientations of various features using relative terms such as vertical, horizontal, above, below etc.. It will be appreciated that these terms refer to the positions and orientations of features when the vehicle is on flat, level ground, and do not preclude use of the vehicle in other orientations.

Claims

1. A tracked vehicle comprising a suspension assembly, the suspension assembly including:a bogie member;a plurality of roller wheels that are rotatably mounted to the bogie member and configured to engage a track of the vehicle; anda suspension mechanism that connects the bogie member to a body of the vehicle and is configured to allow the bogie member to move in a vertical direction with respect to the body of the vehicle, the suspension mechanism being configured to at least substantially prevent the bogie member from pivoting with respect to the body of the vehicle while the bogie member remains at a given height with respect to the body of the vehicle.

2. A tracked vehicle according to Claim 1, wherein the suspension mechanism is further configured to at least substantially prevent the bogie member from pivoting with respect to the body of the vehicle during vertical movement of the bogie member with respect to the body of the vehicle.

3. A tracked vehicle according to Claim 1 or Claim 2, wherein the suspension mechanism comprises a linkage mechanism including a first linkage member and a second linkage member, the first linkage member being pivotally connected to the body of the vehicle at a first pivot point and pivotally connected to the bogie member at a second pivot point, and the second linkage member being pivotally connected to the body of the vehicle at a third pivot point and pivotally connected to the bogie member at a fourth pivot point.

4. A tracked vehicle according to Claim 3, wherein the vehicle has a front and a rear, wherein the first and second linkage members are trailing arms that extend away from the first and third pivot points in a direction towards the rear of the vehicle.

5. A tracked vehicle according to any preceding claim, wherein the suspension mechanism comprises at least one linkage member connecting the bogie member tothe body of the vehicle that is configured to be deflected in a lateral direction during cornering of the vehicle in order to absorb cornering forces.

6. A tracked vehicle according to Claim 5, wherein the laterally deflectable linkage member has a lateral stiffness of less than 20,000N / m or less than 15,000N / m for every Kg of total vehicle weight and / or is configured to be deflected in a lateral direction by a distance of at least 2.5% of the distance between the point at which it is connected to the body of the vehicle and the point at which it is connected to the bogie member during normal use of the vehicle.

7. A tracked vehicle according to any preceding claim, wherein the bogie member is located inboard of the track at a location between the track and the body of the vehicle.

8. A tracked vehicle according to any preceding claim, wherein the bogie member is provided with a track guide that extends downwardly therefrom, the track guide being configured to engage an inner side edge of the track in order to prevent the track from moving off the roller wheels in a direction towards the body of the vehicle.

9. A tracked vehicle according to Claim 8, wherein the track guide comprises a plate-like body that extends in a plane that is parallel to the inner side edge of the track and parallel to a longitudinal direction of the vehicle.

10. A tracked vehicle according to Claim 8 or Claim 9, wherein the track comprises a belt and a plurality of treads that extend outwardly from an outer surface of the belt of the track, wherein the track guide extends to a lower edge that is located below the outer surface of the belt of the track but above the distal ends of the treads of the track.

11. A tracked vehicle according to any preceding claim, wherein the bogie member is provided with a center guide that extends outwardly therefrom, wherein the track comprises a belt and a centering formation that extends inwardly from an inner surface of the belt, the center guide comprising at least one guide member that is configured to engage the centering formation in order to prevent the track from moving in a lateral direction with respect to the bogie member.

12. A tracked vehicle according to Claim 11, wherein the center guide comprises a first guide member located on a first side of the centering formation and a second guide member located on an opposed second side of the centering formation.

13. A tracked vehicle according to Claim 11 or Claim 12, wherein the guide member(s) are plate-like and extend in plane(s) that are parallel to a longitudinal direction of the track and / or the vehicle.

14. A tracked vehicle according to any preceding claim, further comprising an antioscillation device that extends outwardly from the body of the vehicle, the antioscillation device being configured to engage an upper portion of the track in order to limit oscillation of the track.

15. A tracked vehicle according to Claim 14, wherein the anti-oscillation device comprises a plate-like engagement member that extends in a plane that is at least substantially parallel to the upper portion of the track.

16. A tracked vehicle according to Claim 15, wherein the engagement member extends across at least 75% or at least 90% of the width of the track.

17. A tracked vehicle according to Claim 15 or Claim 16, wherein the engagement member has a length that is at least 30% or at least 40% of the length of the track but less than 75% or less than 60% of the length of the track as viewed from above the vehicle.

18. A tracked vehicle according to any of Claims 14 to 17, wherein the track comprises a belt and a centering formation that extends inwardly from an inner surface of the belt and is configured to be received in or between a plurality of upper idler wheels of the vehicle, wherein the distance between the anti-oscillation device and an outer contact surface of the track is less than the distance by which the centering formation extends from the inner surface of the belt, preferably less than 80% of the distance by which the centering formation extends from the inner surface of the belt.

19. A tracked vehicle according to any preceding claim further comprising a drive wheel that is engaged with and configured to drive the track, wherein the drive wheel is provided with a track realignment device that extends outwardly from an inner side of the drive wheel in a direction towards the body of the vehicle, the track realignment device comprising a body having a diameter that increases in the direction extending away from the drive wheel towards the body of the vehicle in order to define a ramped outer engagement surface that is configured to be engaged by the track of the vehicle if the track moves from its intended position with respect to the drive wheel in a direction towards the body of the vehicle.

20. A tracked vehicle according to Claim 19, wherein the track realignment device is configured to rotate together with the drive wheel.

21. A tracked vehicle according to Claim 19 or Claim 20, wherein the track realignment device extends away from the inner side of the drive wheel towards the body of the vehicle by a distance that is at least 50% of the width of the track and / or at least 50% of the distance between the inner edge of the drive wheel and a side of the body of the vehicle.

22. A tracked vehicle comprising a suspension assembly including at least one roller wheel that is configured to engage a track of the vehicle, the roller wheel being connected to a body of the vehicle by a linkage mechanism including at least one linkage member, the linkage member being pivotally connected to the body of the vehicle and configured to enable the roller wheel to move in a vertical direction with respect to the body of the vehicle, wherein the linkage member is configured to be deflected in a lateral direction during cornering of the vehicle in order to absorb cornering forces.

23. A tracked vehicle according to Claim 22, wherein the roller wheel is connected to the linkage member via a bogie member that is pivotally connected to a distal end of the linkage member.

24. A tracked vehicle according to Claim 22 or Claim 23, wherein the linkage member has a lateral stiffness of less than 20,000N / m or less than 15,000N / m forevery Kg of total vehicle weight and / or wherein the linkage member is configured to be deflected in a lateral direction by a distance of at least 2.5% of the distance between the point at which it is connected to the body of the vehicle and the point at which it is connected to the roller wheel or bogie member during normal use of the vehicle.

25. A tracked vehicle according to Claim 23 or Claim 24 when dependent on Claim 23, wherein the linkage mechanism further comprises an additional linkage member that is pivotally connected to the body of the vehicle and pivotally connected to the bogie member, the additional linkage member being configured to at least substantially prevent the bogie member from pivoting about an internal axis with respect to the body of the vehicle.

26. A tracked vehicle comprising a track, the track including a belt and a centering formation that extends inwardly from an inner surface of the belt and is configured to be received in or between a plurality of upper idler wheels of the vehicle, wherein the vehicle further comprises an anti-oscillation device that extends outwardly from the body of the vehicle, the anti-oscillation device being configured to engage an upper portion of the track in order to limit oscillation of the track, wherein the distance between the anti-oscillation device and an outer contact surface of the track is less than the distance by which the centering formation extends from the inner surface of the belt, preferably less than 80% of the distance by which the centering formation extends from the inner surface of the belt.

27. A tracked vehicle according to Claim 26, wherein the anti-oscillation device comprises a plate-like engagement member that extends in a plane that is at least substantially parallel to the upper portion of the track.

28. A tracked vehicle according to Claim 27, wherein the engagement member extends across at least 75% or at least 90% of the width of the track.

29. A tracked vehicle according to Claim 27 or Claim 28, wherein the engagement member has a length that is at least 30% or at least 40% of the length of the track but less than 75% or less than 60% of the length of the track as viewed from above the vehicle.

30. A tracked vehicle comprising a track, a drive wheel that is engaged with and configured to drive the track, and a track realignment device that extends outwardly from an inner side of the drive wheel in a direction towards the body of the vehicle, the track realignment device comprising a body having a diameter that increases in the direction extending away from the drive wheel towards the body of the vehicle in order to define a ramped outer engagement surface that is configured to be engaged by the track of the vehicle if the track moves from its intended position with respect to the drive wheel in a direction towards the body of the vehicle.

31. A tracked vehicle according to Claim 30, wherein track realignment device is configured to rotate together with the drive wheel.

32. A tracked vehicle according to Claim 30 or Claim 31, wherein the track realignment device extends away from the inner side of the drive wheel towards the body of the vehicle by a distance that is at least 50% of the width of the track and / or at least 50% of the distance between the inner edge of the drive wheel and a side of the body of the vehicle.

33. A tracked vehicle according to any preceding claim, wherein the vehicle is a high-speed, scale tracked vehicle, for example a tracked vehicle having a track that is able to rotate at a rate of at least 90rpm during normal use of the vehicle and a length of less than 2.5m or a weight of less than 150Kg.

34. An asymmetric track for a tracked vehicle, the track having an outer side and an inner side;wherein the track comprises a belt and a plurality of asymmetric treads that extend outwardly from an outer surface of the belt;wherein each of the treads extends in a width direction of the belt between an outer end located towards the outer side of the track and an inner end located towards the inner side of the track, and has a height H in a direction extending away from the outer surface of the belt;wherein each of the treads comprises a central portion and an outer portion that extends from the central portion of the tread to the outer end of the tread;wherein the height H of each of the treads decreases across the width W1 of the outer portion of the tread in a direction from the central portion towards the outer end of the tread in order to provide a region of reduced tread height towards the outer side of the track which is greater than any region of reduced tread height provided in the tread towards the inner side of the track.

35. A track according to Claim 34, wherein the width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread is at least 25% or at least 40% of the total width W of the tread.

36. A track according to Claim 34 or Claim 35, wherein the width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread is at least 1.5 times greater than the height H of the tread at its highest point.

37. A track according to any of Claims 34 to 36, wherein each of the treads further comprises an inner portion that extends from the central portion of the tread to the inner end of the tread, wherein the height H of each of the treads decreases across the width W2 of the inner portion of the tread in a direction from the central portion towards the inner end of the tread, wherein the width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread is greater than the width W2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread.

38. A track according to Claim 37, wherein the width W1 of the outer portion of the tread over which the height H of the tread decreases towards the outer end of the tread is at least twice the width \N2 of the inner portion of the tread over which the height H of the tread decreases towards the inner end of the tread.

39. A track according to any of Claims 34 to 40, wherein the outer portion of the tread has a distal end facing away from the belt of the track that is convexly curved when viewed from a direction aligned with a length direction of the track such that the rate of decrease in the height H of the tread across the outer portion of the tread increases in the direction from the central portion towards the outer end of the tread.

40. A tracked vehicle comprising a body, a first track according to any of Claims 34 to 39 mounted on a first side of the body of the vehicle, and a second track according to any of Claims 34 to 39 mounted on an opposed second side of the body of the vehicle, wherein the inner side of each of the tracks faces inwardly towards the body of the vehicle and the outer side of each of the tracks faces outwardly away from the body of the vehicle.

41. A tracked vehicle according to Claim 40, wherein the vehicle is a high-speed, scale tracked vehicle, for example a tracked vehicle having a track that is able to rotate at a rate of at least 90rpm during normal use of the vehicle and a length of less than 2.5m or a weight of less than 150Kg.

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