Traction bar, ramp apparatus and haulage vehicle

Abstract

A traction-increasing bar 100 for providing grip to traffic on a surface 102 is provided. Bar 100 has a base 104 couplable to the surface, first and second sides 106, 108 extending perpendicular to th

Description

Field of the Invention The present invention relates to traction enhancing devices. In particular, the present invention relates to traction bars for ramps and haulage vehicles. Background of the Invention In many industries, specialised vehicles are transported between work sites by haulage vehicles. For example, vehicular machinery required on a construction site is transported to the site on a trailer or rigid truck where the machinery is operated. It is advantageous to load specialised vehicles under their own steam onto haulage vehicles, i.e., to drive the specialised vehicle onto the haulage vehicle, rather than using a third piece of equipment, such as a crane. For efficiency, haulage vehicles must be adapted to carry a wide range of specialised vehicles having different sizes, shapes, tractive elements etc. For example, some specialised vehicles comprise wheels and tyres while others comprise endless tracks for ground engagement. Various accessories and devices have been developed to adapt haulage vehicles for the loading and unloading of a variety of specialised vehicles. One such device is the traction bar which aims to provide grip to vehicles driving up a ramp or sloped part of a deck while being loaded onto a haulage vehicle, such as a trailer or rigid truck. Traction bars may be provided along sides, sometimes called side raves, of a ramp or sloped part of a deck. Traction bars are often attached to the side rave via welded joints. In use, traction bars intermesh with treads of a vehicle’s tyres or with plates, or shoes, of a vehicle’s tracks to assist the machine ascend the slope. Typically, these traction bars are formed from rolled section steel, in readily available shapes such as round, square, or equal angle bar. Summary of the Invention At its most general, the present invention provides a traction enhancing device, substantially in the shape of a bar, attachable to a surface, such as a ramp or slope, to provide grip, or traction, to traffic, e.g., vehicles such as construction machinery, travelling across the surface. According to a first aspect of the invention, there is provided a traction bar configured to provide grip to traffic travelling across a surface, the traction bar comprising: a base configured to be coupled to the surface; a first side disposed at a first end of the base and a second side disposed at a second, opposite, end of the base, the first side and the second side each being arranged to extend in a direction substantially perpendicular to the base; and a top side connecting a distal end of the first side to a distal end of the second side; wherein a length of the first side is greater than a length of the second side such that the top side is sloped with respect to the base. As the first side is longer than the second side, the top side must be sloped with respect to the base. As such, a cross-sectional shape of the traction bar may be asymmetrical. As an example, a cross-sectional shape of the traction bar may be substantially right trapezium shaped. The sloped top side may be substantially straight and inclined with respect to the base. Alternatively, the sloped top side may comprise a curve or a plurality of curves. The top side may comprise a curved portion and a straight portion. The top side may be sloped in any suitable way to connect distal ends of the first and second sides. The traction bar of the present invention has a uniquely advantageous shape. The longer first side, extending substantially perpendicularly to the base, offers a secure and strong ledge, or shelf, to traffic travelling across a surface for improved grip. Simultaneously, the shorter second side and sloped top side provide a substantially tapering shape to the bar so that the bar is compact and avoids being damaged or becoming detached from the surface by a pinching action of tractive elements of traffic travelling across a surface. Some conventional traction bars comprise a base and opposite sides having equal height such that a top side is substantially parallel to the base. For example, such a bar may have a rectangular cross-sectional shape. These bars are prone to being gripped or pinched by the surface engaging parts of the vehicles travelling over the surface. For example, treads of tyres or track plates of vehicle tracks may engage with both (similar height) sides of the bar to grip or pinch the bar. As the vehicle passes over the bar, the gripping or pinching action may not reliably be released and the vehicle may damage the traction bar or even rip it from the surface. Other traction bars comprise a shape that inhibits the gripping or pinching action by vehicles travelling over the surface by providing a substantially curved or rounded bar. For example, such a bar may have a circular cross-sectional shape. While these bars are less likely to be damaged by vehicles gripping them while travelling over them, their shape demands large welds, particularly as the curve radius increases, which lead to substantially weaker attachment than other bars. So, these bars are also prone to becoming detached from the surface in normal use due to large welds providing weak attachment. The large welds are also more difficult and expensive to execute. Moreover, rounded bars provide substantially less grip to vehicles as the surface engaging parts of the vehicles often slide over the curved surfaces of the rounded bars. In general, shapes that do not provide a side that is substantially perpendicular to the surface over which the vehicle travels have been found to provide insufficient grip. A compounding issue has been that, to improve strength and robustness, additional materials, e.g., timber or steel, are often added to ramps or slopes between the side raves where the traction bars are disposed. For example, timber may be added to a ramp for reinforcement, e.g., underneath a top, grip-providing surface, or even as the top surface, raising a height of the top surface. To effectively provide grip, the traction bars must protrude over these additional materials, so their addition has led to a steady increase in a required height of traction bars. For rectangular bars, taller / larger bars merely provide greater leverage for vehicles to grip them and rip them off. For rounded bars, increasing the size, and therefore radius, makes the weld attachment even weaker. So, increasing the size of existing traction bars has not provided a solution and an innovative new traction bar shape is required. The asymmetry of the traction bar of the present invention provides the dual advantages of providing sufficient and secure grip to vehicles and reduced risk of damage or detachment during normal use. Further, base of the traction bar of the present invention is simple and cost-effective to weld securely in place. Historically, readily available material shapes such as round or square bars have been preferred for cost reasons and other, asymmetrical, shapes have not been considered. The long first edge perpendicular to the base provides sufficient grip to a vehicle. The short second edge and sloped top side do not provide to a vehicle sufficient purchase on the bar as a whole for the vehicle to grip the bar and damage or detach it. In this way, the present invention overcomes the problem associated with earlier traction bars. In some embodiments, the top side comprises a curved portion arranged proximate the distal end of the first side. By providing a curved portion at the distal end of the first side, the traction bar tapers to a curved point rather than a sharp point. In this way, a risk of causing damage to vehicles travelling over the traction bar may be reduced and the safety of the traction bar may be improved. In some embodiments, the top side comprises a further curved portion arranged proximate the distal end of the second side to further remove sharp corners from the traction bar. In some embodiments, the length of the first side is at least 2 times greater than the length of the second side. The second side being less than or equal to half the height of the first side has been found to reduce a risk of the traction bar being damaged or detached by a vehicle in use. In some embodiments, the length of the first side is at least 3 times greater than the length of the second side. The second side being less than or equal to a third the height of the first side has been found to further reduce a risk of the traction bar being damaged or detached by a vehicle in use. In some embodiments, the length of the first side is around 3.75 times greater than the length of the second side. The inventors have found that a ratio of first side length to second side length of approximately 1:3.75 (e.g., 8:30) provides an optimal shape for providing grip while reducing a risk of the traction bar being damaged or detached by a vehicle in use. The height of the traction bar may be selected with reference to the surface to which it is configured to be coupled. For example, where a traction bar is configured to be coupled to a ramp having recessed side raves or additional, reinforcing, materials provided between the side raves, a greater overall traction bar height may be selected. The traction bars of the present invention may be used with a spacer, e.g., a cuboid bar placed between the traction bar and the surface, to increase a height of the traction bar without requiring adjustment of the traction bar itself. In some embodiments, the first side and the second side are arranged substantially parallel to one another. In other words, in some embodiments the base is flat. In this way, the traction bar may be formed from a readily available bar material, e.g., square bar. In some embodiments, the traction bar may be formed of a sheet material, rather than a bar material. In some embodiments, a width of the traction bar is substantially equal to the length of the base such that the traction bar is substantially unobstructive to the surface. In this way the traction bar may be used by vehicles require extra traction and may be avoided by vehicles which do not, or which require a substantially flat surface. For example, a vehicle comprising a roller or rollers may find traction bars to present a significant obstacle. In this way, traction bars may be installed on a surface without limiting the suitability of the surface for vehicles. In some embodiments, the width of the traction bar is greater than the length of the base such that the traction bar extends transversely across the surface. A surface may be provided with traction bars that extend across a portion of the surface from one side to the other. In some embodiments, the traction bar may extend across a majority of, or substantially a whole of, the surface. In this way, the traction bar may provide traction across a wider area and may be more effective for vehicles requiring additional traction. In some embodiments, at least one of the first end of the base and the second end of the base comprises a chamfer configured to increase a coupling surface area of the traction bar. In this way, a greater surface area of the bar available for joining to welding wire during welding is provided. As a result, greater penetration for the welding wire into the bar is achieved and a stronger weld is provided. According to a further aspect of the invention, there is provided a ramp apparatus configured to provide a path between a first level and a second level, the ramp apparatus comprising a ramp and a plurality of traction bars according to the first aspect. The ramp apparatus may be configured to be connected to a vehicle such as a trailer, rigid truck or haulage vehicle. The ramp apparatus may provide a sloping surface between a first level and a second level. The ramp apparatus may be one of a pair of ramps, or a half ramp. Each ramp of a pair may be configured to support one side of a vehicle, e.g., one track. The ramp may be a hinged ramp, e.g., configured to be rotated between a stowed and a deployed position. The ramp may comprise a hinge, i.e., the ramp may itself be foldable, such that a first portion of the ramp may be rotated with respect to a second portion of the ramp between a stowed and a deployed position. The ramp may comprise a first sloping surface having a first gradient and a second sloping surface having a second gradient. In some embodiments, for each traction bar, the base is configured to be arranged substantially parallel to a path surface of the ramp. In this way, a secure joint may be formed between the traction bar and the ramp. For example, it may be simple and secure to weld the traction bar to the ramp. In some embodiments, for each traction bar, the first side is arranged substantially parallel to a top edge of the ramp. In this way, the traction bars are arranged substantially parallel to one another. In this way, when vehicles travel up or down the ramp, the first sides of the traction bars may be arranged substantially perpendicular to the direction of travel to provide maximum traction to the vehicles. In some embodiments, for each traction bar, the first side is arranged closer to a top edge of the ramp than the second side. In this way, for a vehicle travelling up the ramp, the first side provides a secure ledge or shelf to grip on to and push off from. Similarly, when a vehicle is travelling down the ramp, the first side provides a secure ledge or shelf to arrest or decelerate the descending vehicle and provide grip. In both directions, the first side counters gravity to provide grip to a vehicle. In some embodiments, each traction bar is separated from any adjacent traction bar by a predetermined interval. For example, the predetermined interval may be a common or widely adopted interval (or pitch) between track plates of a tracked vehicle so that adjacent tracks of a vehicle may engage with adjacent traction bars to provide enhanced grip. In some embodiments, the predetermined intervals between adjacent traction bars are substantially uneven such that the traction bars are not evenly spaced. In other words, a pitch of the traction bars may be uneven. In this way, the ramp apparatus may be suitable for a variety of tracked vehicles having a variety of track plate lengths. In some embodiments, each traction bar is arranged substantially equidistant from a peripheral side edge of the ramp. In this case, the ramp apparatus may be one of a pair of ramps. The traction bars may be arranged on a side rave of the ramp. The traction bars may be substantially aligned along the side rave of the ramp. In some embodiments, each traction barof a first subset of the plurality of traction bars is arranged substantially equidistant from a first peripheral side edge of the ramp; and each traction bar of a second subset of the plurality of traction bars arranged substantially equidistant from a second peripheral side edge of the ramp. In this case, the ramp apparatus may be configured to support a vehicle across the vehicle’s whole width. The ramp apparatus may extend as wide as or wider than the width of an axle of the vehicle. Traction bars may be disposed in two subsets along opposite peripheral side edges of the ramp, e.g., along opposite side raves. In some cases, a third, or even a fourth, subset of traction bars may be provided between the first and second subset such that traction bars are spaced across a width of the ramp. The subsets of traction bars may be evenly spaced to provide predictable grip and avoid insufficient traction, or a loss of traction, causing rotation of a vehicle on the ramp. In some embodiments, each traction bar of the first subset is arranged offset from a respective traction bar of the second subset such that, for each traction bar, a distance the top edge of the ramp is substantially unique. For example, a first traction bar of the first subset may be arranged closest to the top edge of the ramp, followed by the first traction bar of the second subset, then the second traction bar of the first subset, second traction bar of the second subset and so on. In this way, for a vehicle engaging with both subsets of traction bars, an effective distance in the direct of travel between subsequent traction bars may be halved. Thereby, the arrangement effectively provides traction bars at smaller intervals (higher frequency) without increasing a number of traction bars required. In this way, a grip provided by a given number of traction bars to a vehicle engaging with both subsets of traction bars may be increased. Such a vehicle may be a vehicle spanning the width of the ramp apparatus. In some embodiments, the traction bars are arranged substantially parallel to one another. In this way, all the traction bars on the ramp apparatus may be well aligned act to improve a grip long the ramp in the direction of travel. In some embodiments, the ramp comprises a textured surface arranged to provide additional traction. The textured surface may comprise a mesh surface or a patterned, e.g., ridged, surface. Other types of textured surface may also be used. The textured surface may be formed of resilient materials such as steel for longevity of the surface. In some embodiments, the textured surface is arranged to provide additional traction over a strong but low traction surface such as steel plate or timber boards. The textured surface may be arranged to be under wheels or tracks of vehicles travelling along the ramp. Where a textured surface is provided, the traction bars of the ramp apparatus may be larger and / or taller to protrude sufficiently above the textured surface to provide grip to vehicles. According to a third aspect of the invention, there is provided a haulage vehicle for transporting a subject vehicle, the haulage vehicle comprising a deck configured to receive the subject vehicle; wherein the deck comprises a sloped portion comprising: a surface configured to receive and support the subject vehicle; and a plurality of traction bars according to the first aspect, the plurality of traction bars being configured to provide grip to the subject vehicle during loading and / or unloading from the deck via the sloped portion. The haulage vehicle may be a trailer, e.g., a trailer configured to transport vehicles. Alternatively, the haulage vehicle may be a rigid truck. The subject vehicle may be a specialised vehicle such as an item of construction machinery or equipment. The subject vehicle may be a tracked vehicle, i.e., comprising endless tracks. For example, the subject vehicle may comprise a tracked excavator or loader. The sloped portion of the deck of the haulage vehicle may share many features with the ramp apparatus of the previous aspect of the invention. Accordingly, features disclosed with respect to the ramp apparatus may also be used on the sloped portion of the deck of the haulage vehicle. In some embodiments, for each traction bar, the first side is arranged closer to a top edge of the sloped portion than the second side. In this way, for a vehicle travelling up the sloped portion, the first side provides a secure ledge or shelf to grip on to and push off from. Similarly, when a vehicle is travelling down the sloped portion, the first side provides a secure ledge or shelf to arrest or decelerate the descending vehicle and provide grip. In both directions, the first side counters gravity to provide grip to a vehicle. In some embodiments, each traction bar is separated from any adjacent traction bar by a predetermined interval; and wherein the predetermined intervals between adjacent traction bars are substantially uneven such that the traction bars are not evenly spaced. In other words, a pitch of the traction bars may be uneven. In this way, the ramp apparatus may be suitable for a variety of tracked vehicles having a variety of track plate lengths. In some embodiments, each traction barof a first subset of the plurality of traction bars is arranged substantially equidistant from a first peripheral side edge of the sloped portion; and each traction bar of a second subset of the plurality of traction bars arranged substantially equidistant from a second peripheral side edge of the sloped portion. Accordingly, the sloped portion may be configured to support a vehicle across the vehicle’s whole width. The sloped portion may extend as wide as or wider than the width of an axle of the vehicle. Traction bars may be disposed in two subsets along opposite peripheral side edges of the sloped portion, e.g., along opposite side raves. In some cases, a third, or even a fourth, subset of traction bars may be provided between the first and second subset such that traction bars are spaced across a width of the sloped portion. The subsets of traction bars may be evenly spaced to provide predictable grip and avoid insufficient traction, or a loss of traction, causing rotation of a vehicle on the sloped portion. In some embodiments, each traction bar of the first subset is arranged offset from a respective traction bar of the second subset such that, for each traction bar, a distance the top edge of the sloped portion is substantially unique. For example, a first traction bar of the first subset may be arranged closest to the top edge of the sloped portion, followed by the first traction bar of the second subset, then the second traction bar of the first subset, second traction bar of the second subset and so on. In this way, for a vehicle engaging with both subsets of traction bars, an effective distance in the direct of travel between subsequent traction bars may be halved. Thereby, the arrangement effectively provides traction bars at smaller intervals (higher frequency) without increasing a number of traction bars required. In this way, a grip provided by a given number of traction bars to a vehicle engaging with both subsets of traction bars may be increased. Such a vehicle may be a vehicle spanning the width of the sloped portion. Brief Description of the Drawings Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 shows a schematic view of an example of a traction bar according to the prior art; Figure 2A shows a side view of a traction bar according to an embodiment of the first aspect of the present invention; Figure 2B shows an isometric view of the traction bar of Fig. 2A in use; Figure 3 shows a schematic diagram of the traction bar of Fig. 2A in use; and Figure 4 shows an isometric view of a deck of a haulage vehicle according to an embodiment of a further aspect of the present invention. Detailed Description With reference to Figure 1, there is illustrated a schematic view of an example of a traction bar A according to the prior art. The traction bar A is substantially cuboidal in shape, having a substantially square cross section. The cross section of traction bar A is substantially symmetrical. The traction bar A is arranged on a sloping surface B and extends transversely inwards from an edge of the sloping surface B. Three track shoes C1, C2, C3 of a tracked vehicle are shown in Fig 1. The tracked vehicle is travelling up the ramp in the direction shown by arrow D. Accordingly, as the vehicle progresses in the direction D, the track shoes will be laid down on the surface B in the order C1, C2, C3. As the vehicle passes the traction bar A, the track shoes will be picked up off the surface B in the order C1, C2, C3. In Fig. 1, the first track shoe C1 is laid down on the surface B is downhill of the traction bar A and the second track shoe C2 is about to be laid down on the surface B uphill of traction bar A. When the second track shoe C2 is laid down, the traction bar A will be disposed between track shoes C1 and C2. At that point, the straight and substantially equal height sides A’ of the traction bar A will each be engaged with a side of the track shoes C1 and C2. Next the third track shoe C3 will be laid down on the surface B uphill of traction bar A and the second track shoe C2. When the first track shoe C1 is lifted up, i.e., once the vehicle has mostly passed over the traction bar A along the ramp in the direction D, the traction bar A may be pinched between the first track shoe C1 and the second track shoe C2. Due to the relatively large area of engagement between the sides of the traction bar A and the track shoes C1 and C2, the track shoes C1 and C2 may exert a firm grip on the traction bar A. The force gripping the traction bar A may overcome the force holding the traction bar A on the surface B and the tracked vehicle may lift the traction bar A off the surface B. In this way, the tracked vehicle may detach the traction bars of the prior art from surfaces, rendering them unable to provide traction to other vehicles, or to the vehicle in question as it descends the surface B (travelling in the opposite direction to the arrow D). With reference to Figure 2A and 2B, there is illustrated a traction bar 100 according to the present invention. The traction bar 100 is configured to provide grip to traffic travelling across a surface 102. The traction bar 100 comprises a base 104. The base 104 is configured to be coupled to the surface 102’. The traction bar 100 comprises a first side 106 disposed at a first end 104’ of the base 104. The traction bar 100 also comprises a second side 108 disposed at a second, opposite, end 104” of the base 104. The first side 106 and the second side 108 are each arranged to extend in a direction substantially perpendicular to the base 104. The traction bar 100 further comprises a top side 110. The top side 110 connects a distal end 106’ of the first side 106 to a distal end 108’ of the second side 108. A length of the first side 106 is greater than a length of the second side 108 such that the top side 110 is sloped with respect to the base 104. The top side 110 comprises a curved portion 110’ arranged proximate the distal end 106’ of the first side 106. The curved portion 110’ provides a rounded and not sharp edge to the traction bar 100 to reduce a risk of injury or damage caused by such a sharp point. The first side 106 and the second side 108 are arranged substantially parallel to one another and substantially perpendicular to the base 104. The length of the first side 106 is around 3.75 times greater than the length of the second side 108. The length of the first side 106 is measured between the base 104 and a highest point of the curved portion 110’. The length of the second side 108 is measured between the base 104 and a lowest point of the top side 110. A chamfer may be provided at the first end 104’ of the base 104 and / or the second end 104” of the base 104 to increase a coupling surface area of the traction bar 100. In use, the chamfer may be filled by a weld such that the shape of the traction bar in use is substantially similar to the shape shown in Figs. 2A and 2B. As shown in Fig. 2B, a width of the traction bar 100 is substantially equal to the length of the base 104 such that the traction bar 100 is substantially unobstructive to the surface 102. The surface 102’ may, for example, be a side rave of the surface 102. In the embodiment of Fig. 2B, the base 104 is arranged substantially parallel to the surface 102’ while the first side 106 is arranged substantially parallel to a top edge of the surface 102 and closer to the top edge than the second side 108. The surface 102 comprises a textured surface 102” arranged to provide additional traction. In Fig. 2B, the texture surface 102” is a steel mesh. With reference to Figure 3, there is illustrated a schematic view of the traction bar 100 in use. The traction bar 100 is arranged on a sloping surface 102 and extends transversely inwards from an edge of the sloping surface 102. The first, longer, surface 106 of the traction bar 100 is arranged uphill of the second, shorter, surface 108. Three track shoes C1, C2, C3 of a tracked vehicle are shown in Fig 3. The tracked vehicle is travelling up the surface 102 in the direction shown by arrow D. Accordingly, as the vehicle progresses in the direction D, the track shoes will be laid down on the surface 102 in the order C1 -> C2 -> C3. As the vehicle passes the traction bar 100, the track shoes will be picked up off the surface 102 in the order C1 -> C2 -> C3. In Fig. 3, the first track shoe C1 is laid down on the surface B is downhill of the traction bar 100 and the second track shoe C2 is about to be laid down on the surface B uphill of traction bar 100. When the second track shoe C2 is laid down, the traction bar 100 will be disposed between track shoes C1 and C2. At that point, the first side 106 of the traction bar 100 will engage with a downhill side of the second track shoe C2. In this way, the tracked vehicle may derive grip from the traction bar 100. Contemporaneously, because the second side 108 is shorter than the first side 106, the second side 108 of the traction bar 100 will not engage, or will engage only over a small area, with the uphill side of track shoe C1. Next the third track shoe C3 will be laid down on the surface 102 uphill of traction bar 100 and the second track shoe C2. When the first track shoe C1 is lifted up, i.e., once the vehicle has mostly passed over the traction bar 100 along the surface 102 in the direction D, the traction bar 100 may not be pinched between the first track shoe C1 and the second track shoe C2. Due to the relatively small height of the second side 108 of the traction bar 100, only a small proportion, if any, of the height of the uphill side of the first track shoe C1 may be engaged with the traction bar and therefore the first track shoe C1 may be unstable in that engagement. So, the first track shoe C1 may slide over the second side 108 and top side 110 of the traction bar and not grip the traction bar 100. Further, the first track shoe C1 may exert a force on the second side 108 relatively close to the base 104, as the second side 108 is short. Therefore, a moment arm of the force exerted on the traction bar 100 by the first track shoe C1 is reduced such that a torque exerted on the traction bar 100 by the first track shoe C1 is reduced. The reduced torque may be insufficient to dislodge the traction bar 100 and instead, the first track shoe C1 may slide over the second side 108 and top side 110 of the traction bar and not grip the traction bar 100. As such, any force exerted on the traction bar 100 by the track shoes C1 and C2 may not be sufficient to grip the traction bar 100 and overcome the force holding the traction bar 100 on the surface 102. So, the shape of the traction bar 100 may avoid a tracked vehicle lifting the traction bar 100 off the surface 102. In this way, the traction bar 100 of the present invention overcomes or ameliorates the problem of traction bars of the prior art being detached from surfaces by tracked vehicles in normal use. Figure 4 shows an isometric view of a deck 400 of a haulage vehicle according to the present invention. The haulage vehicle may be suitable for transporting a subject vehicle. The subject vehicle may be a specialised vehicle configured to perform a specific task at a site and not configured for long distance transport, e.g., between sites. Such a vehicle may include a construction vehicle such as an excavator. The haulage vehicle of Fig. 4 comprises the deck 400 which is configured to receive the subject vehicle. The deck 400 comprises a sloped portion 402. In the embodiment of Fig. 4, the sloped portion 402 comprises a first sloping surface 402’ having a first gradient and a second sloping surface 402” having a second gradient. The sloped portion 402 comprises a surface 404 configured to receive and support the subject vehicle. The sloped portion 402 further comprises a plurality of traction bars 406. In Fig. 4, the traction bars 406 are the traction bar 100 of Fig. 2A and 2B. The plurality of traction bars 406 is configured to provide grip to the subject vehicle during loading and / or unloading from the deck 400 via the sloped portion 402. As shown in Fig. 4, the first, longer, side of each traction bar 406 is arranged substantially parallel to a top edge 408 of the ramp. The traction bars 406 are arranged substantially parallel to one another and the first, longer, side of each traction bar 406 is arranged closer to a top edge 408 of the sloped portion 402 than the second, shorter, side. In Fig. 4, the traction bars 406 are arranged in a first subset arranged on a left hand side 410 of the deck 400 and a second subset arranged on a right hand side 412 of the deck 400. Each traction bar 406 of the first subset is arranged substantially equidistant from a first peripheral side edge, the left hand side 410, of the sloped portion 402. Each traction bar 406 of the second subset is arranged substantially equidistant from a second peripheral side edge, the right hand side 412, of the sloped portion 402. In each subset, each traction bar 406 is separated from adjacent traction bars 406 by a predetermined interval. In Fig. 4, the predetermined interval between adjacent traction bars 406 is substantially identical for all the traction bars 406. In this way, the traction bars are evenly spaced to provide traction in an even distribution along the sloped portion 402. In other embodiments, the predetermined interval between adjacent traction bars 406 in the first subset may be a first interval, while the interval between adjacent traction bars 406 in the second subset may be a second, different, interval. In this way, the first subset of traction bars 406 may be spaced for suitability with a first type of vehicle, while the second subset of traction bars 406 may be spaced for suitability with a second type of vehicle. In other embodiments, the predetermined intervals between adjacent traction bars 406 may be substantially uneven such that the traction bars 406 are not evenly spaced. In this way, the traction bars 406 may be spaced for suitability with a wide variety of vehicles. In some embodiments, each traction bar 406 of the first subset may be arranged offset from a respective traction bar 406 of the second subset such that, for each traction bar, a distance from the top edge 408 of the sloped portion 402 is substantially unique. In this way, when viewed in order along a direction of travel along the sloped portion 402, the traction bars 406 may be provided alternately by the first subset and the second subset in a stepwise manner. In this way, the effective frequency of the traction bars 406 may be doubled without providing twice as many traction bars 406. In an example, the traction bars of each subset are evenly spaced to provide a regular stepwise arrangement of traction bars. The sloped portion 402 comprises a textured surface 414 arranged to provide additional traction. In Fig. 4, the textured surface 414 comprises a steel mesh, e.g., a painted steel mesh. The present invention is not limited to the specific examples or structures illustrated. Further embodiments within the scope of the present invention may be envisaged that have not been described above, for example, the traction bar be used to provide traction to any suitable surface, ramp or vehicle. The traction bar may comprise any suitable shape or size. The traction bar may be formed of any suitable materials and using any suitable manufacturing methods. The traction bar may be attached to a surface in any suitable manner. For example, the traction bar may be attached the surface by a fastener. In another example, the traction bar may be formed integrally with the surface. The ramp apparatus and / or haulage vehicle may comprise a greater or lesser number of components than are illustrated in the figures. For example, the deck of the haulage vehicle may comprise any suitable number and type of traction bars. Traction bars of different configurations may be used together on a haulage vehicle. To provide a resilient traction bar to provide grip to traffic travelling across a surface, an innovative traction bar configured to resist damage or detachment in normal use is required. The device of the present invention provides an innovative shape to enable the bar to provide sufficient grip to a vehicle travelling over it, while resisting being gripped or pinched and ripped away from the surface by the passing vehicle. There has been herein described a traction bar configured to provide grip to traffic travelling across a surface, the traction bar comprising: a base configured to be coupled to the surface; a first side disposed at a first end of the base and a second side disposed at a second, opposite, end of the base, the first side and the second side each being arranged to extend in a direction substantially perpendicular to the base; and a top side connecting a distal end of the first side to a distal end of the second side; wherein a length of the first side is greater than a length of the second side such that the top side is sloped with respect to the base. There is also described a ramp apparatus and a haulage vehicle each comprising a plurality of traction bars configured to provide grip during loading and / or unloading operations.

Claims

1. A traction bar configured to provide grip to traffic travelling across a surface, the traction bar comprising:a base configured to be coupled to the surface;a first side disposed at a first end of the base and a second side disposed at a second, opposite, end of the base, the first side and the second side each being arranged to extend in a direction substantially perpendicular to the base; anda top side connecting a distal end of the first side to a distal end of the second side;wherein a length of the first side is greater than a length of the second side such that the top side is sloped with respect to the base.

2. The traction bar of claim 1, wherein the top side comprises a curved portion arranged proximate the distal end of the first side.

3. The traction bar of claim 1 or claim 2, wherein the length of the first side is at least 2 times greater than the length of the second side.

4. The traction bar of any preceding claim wherein the length of the first side is at least 3 times greater than the length of the second side.

5. The traction bar of any preceding claim wherein the length of the first side is around 3.75 times greater than the length of the second side.

6. The traction bar of any preceding claim, wherein the first side and the second side are arranged substantially parallel to one another.

7. The traction bar of any preceding claim, wherein a width of the traction bar is substantially equal to the length of the base such that the traction bar is substantially unobstructive to the surface.

8. The traction bar of any one of claims 1 to 6, wherein the width of the traction bar is greater than the length of the base such that the traction bar extends transversely across the surface.

9. The traction bar of any preceding claim, wherein at least one of the first end of the base and the second end of the base comprises a chamfer configured to increase a coupling surface area of the traction bar.

10. A ramp apparatus configured to provide a path between a first level and a second level, the ramp apparatus comprising a ramp and a plurality of traction bars according to any preceding claim.

11. The ramp apparatus of claim 10, wherein, for each traction bar, the base is configured to be arranged substantially parallel to a path surface of the ramp.

12. The ramp apparatus of claim 10 or claim 11, wherein, for each traction bar, the first side is arranged substantially parallel to a top edge of the ramp.

13. The ramp apparatus of any one of claims 10 to 12, wherein, for each traction bar, the first side is arranged closer to a top edge of the ramp than the second side.

14. The ramp apparatus of any one of claims 10 to 12, wherein each traction bar is separated from any adjacent traction bar by a predetermined interval.

15. The ramp apparatus of claim 14, wherein the predetermined intervals between adjacent traction bars are substantially uneven such that the traction bars are not evenly spaced.

16. The ramp apparatus of any one of claims 10 to 15, wherein each traction bar is arranged substantially equidistant from a peripheral side edge of the ramp.

17. The ramp apparatus of any one of claims 10 to 15, wherein each traction bar of a first subset of the plurality of traction bars is arranged substantially equidistant from a first peripheral side edge of the ramp; andeach traction bar of a second subset of the plurality of traction bars arranged substantially equidistant from a second peripheral side edge of the ramp.

18. The ramp apparatus of claim 17, wherein each traction bar of the first subset is arranged offset from a respective traction bar of the second subset such that, for each traction bar, a distance the top edge of the ramp is substantially unique.

19. The ramp apparatus of any one of claims 10 to 18, wherein the traction bars are arranged substantially parallel to one another.

20. The ramp apparatus of any one of claims 10 to 19, wherein the ramp comprises a textured surface arranged to provide additional traction.

21. A haulage vehicle for transporting a subject vehicle, the haulage vehicle comprising a deck configured to receive the subject vehicle; wherein the deck comprises a sloped portion comprising:a surface configured to receive and support the subject vehicle; anda plurality of traction bars according to any one of claims 1 to 8, the plurality of traction bars being configured to provide grip to the subject vehicle during loading and / or unloading from the deck via the sloped portion.

22. The haulage vehicle of claim 21, wherein, for each traction bar, the first side is arranged closer to a top edge of the sloped portion than the second side.

23. The haulage vehicle of claim 21 or claim 22, wherein each traction bar is separated from any adjacent traction bar by a predetermined interval; andwherein the predetermined intervals between adjacent traction bars are substantially uneven such that the traction bars are not evenly spaced.

24. The haulage vehicle of any one of claims 21 to 23, wherein each traction bar of a first subset of the plurality of traction bars is arranged substantially equidistant from a first peripheral side edge of the sloped portion; andeach traction bar of a second subset of the plurality of traction bars arranged substantially equidistant from a second peripheral side edge of the sloped portion.

25. The haulage vehicle of claim 24, wherein each traction bar of the first subset is arranged offset from a respective traction bar of the second subset such that, for each traction bar, a distance the top edge of the sloped portion is substantially unique.

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