A support structure for a trolley-assist system for mining vehicles

Abstract

A support structure 100 comprising: a column 102 with a free-standing reusable base 112, a beam 104 which pivots around an axis (228, Fig. 2) upwards towards the column from a steady-state position, which beam supports an overhead power cable (402, 404, Fig. 4). The beam may be coupled to the upper end of the column via a first hinge joint 120 and / or a releasable mount (224, Fig. 2). The beam may also be pivotable about a longitudinal axis of the column, perhaps using two hinges, which may be formed as a biaxial hinge (226, 228, Fig. 2). In steady state the beam may be supported by means such as a cable 122a, 122b or strut in tension, or a strut in compression. The cable may be attached to the top of the column and the outer end of the beam. The support structure may be: part of a trolley-assist system (Fig. 4) for mining vehicles; one of a plurality of support structures; positioned adjacent a mine haul road; supporting an overhead power cable (402, 404, Fig. 4) for a mining vehicle 316.

Description

Technical Field The present disclosure relates to a support structure, for a trolley-assist system for mining vehicles. In particular, the present disclosure relates to a support structure comprising a pivotable beam. The present disclosure also relates to a trolley-assist system for mining vehicles, a method of assembly of the support structure, and a mining hauling system. Background A trolley assist system is a system in which mining vehicles, such as haul trucks, in open pit mines, are propelled by electrical power along a mining vehicle haul road. This is known to be advantageous because the use of electrical power leads to high savings on fuel costs and reduced CO2 emissions in comparison to well-known systems that may use diesel fuel. However, these trolley-assist systems still require a substantial amount of investment and maintenance to fulfil such advantages. It is known that the terrain of the support surface or the mining vehicle haul road for the trolleyassist system can be naturally variable, uneven or undulating. The terrain may also change over time. Therefore, when using these trolley-assist systems, the mining vehicle haul roads may need be adequately maintained, because uneven surfaces can lead to excessive deflections in the support structures of the trolley-assist systems transmitted by passing mining vehicles. These deflections applied to structural parts of known trolley-assist systems can damage and reduce the lifetime of some of the structural components of the trolley-assist system. As a result, the inventors have appreciated that it would be desirable to provide a support structure for a trolley-assist system that is more adaptable to variable terrain in the mining vehicle haul road, while also being straightforward to install. Summary of Disclosure Embodiments described herein provide a support structure, for a trolley-assist system for mining vehicles, a trolley-assist system for mining vehicles, and a method of assembly of the support structure as defined in the appended independent claims, to which reference should now be made. Preferred or advantageous features of the disclosure are set out in the dependent sub-claims. The present disclosure relates to a support structure, for a trolley-assist system for mining vehicles. The support structure may comprise a column having a first end configured to be coupled to a base, and a second end. The base may be a free-standing reusable base. The support structure may comprise a beam having a first end and a second end. The first end may be coupled to the column proximate the second end such that it is pivotable about an axis orthogonal to a longitudinal axis of the column and orthogonal to a longitudinal axis of the beam. The beam may be configured to support an overhead power cable of a trolley-assist system for providing electrical power to a mining vehicle. The beam may be arranged such that it is only pivotable, about the axis orthogonal to the longitudinal axis of the column and orthogonal to the longitudinal axis of the beam, from a steady-state position towards the second end of the column. According to a first aspect of the present disclosure, there is provided a support structure, for a trolley-assist system for mining vehicles. The support structure comprises a column having a first end configured to be coupled to a base, and a second end. The base is a free-standing reusable base. The support structure further comprises a beam having a first end and a second end. The first end of the beam is coupled to the column proximate the second end. The first end of the beam is coupled to the column proximate the second end such that it is pivotable about an axis orthogonal to a longitudinal axis of the column and orthogonal to a longitudinal axis of the beam. The beam is configured to support an overhead power cable of a trolley-assist system for providing electrical power to a mining vehicle. The beam is arranged such that it is only pivotable, about the axis orthogonal to the longitudinal axis of the column and orthogonal to the longitudinal axis of the beam, from a steady-state position towards the second end of the column. Providing a beam that is coupled such that it is only pivotable about an axis orthogonal to a longitudinal axis of the column and orthogonal to a longitudinal axis of the beam, in particular, only pivotable from a steady-state position towards the second end of the column, is advantageous because it provides a support structure with improved adjustability if the terrain of a mining vehicle haul road is uneven or changes over time. When a mining vehicle travels over these uneven surfaces, it may bounce, leading to oscillations in the overhead cable that can apply an upward pressure on the beam. The beam being pivotably coupled allows the beam to move upwardly in response to any upward forces applied by the mining vehicle. Consequently, this further advantageously, reduces the risk of damage to the beam and / or the support structure as a whole. Further, the relative positioning of the beam can be adjusted easily, particularly in comparison to the known prior art, where the beam is fixedly coupled to the column, thereby fixed relative to the column. The beam being pivotable may reduce installation times and costs. This is because the effort needed with regards to setting and aligning the beam with respect to the column may be reduced. The beam being pivotable ensures that the necessary clearance is maintained between the beam and the overhead power cable. Further still, maintenance costs may be reduced because the beam is less likely to be misaligned or misplaced due to uneven surfaces or terrain. In the present disclosure, the second end of the column preferably refers the upper end of the column, in use. The steady-state position preferably refers to a resting position, in other words, the position the beam returns to after being deflected or pivoted relative to the column or after undergoing a pivoting movement. The column may be configured to be releasably coupled at its first end to a free-standing reusable base. The free-standing reusable base advantageously provides a support for the support structure. The beam may be releasably coupled to the column. The beam may be releasably coupled to the column proximate the second end of the column. The beam may be coupled to the column via a first hinge joint. The first hinge joint advantageously enables relative movement between the beam and the column. The hinge joint may be configured such that, in use, the beam is pivotable in an upward direction. In the present disclosure, upward direction refers to a direction away from the support surface and towards the upper end of the column. The first hinge joint may be releasably securable to the column. The first hinge joint may be releasably securable to the beam. The beam may be pivotable about a longitudinal axis of the column. In other words, the beam may be pivotable from the steady-state position towards the second end of the column and also pivotable about the longitudinal axis of the column. The beam being able to also pivot about the longitudinal axis of the column, further ensures that the beam is able to better withstand forces applied to it and enable more favourable relative movement between the beam and the column. Consequently, this reduces the likely of damage of the beam and the support structure as a whole. The beam may be coupled to the column via a second hinge joint. The second hinge joint advantageously enable further relative movement between the beam and the column, such that the beam can pivot about the longitudinal axis of the column. The second hinge joint may be configured to restrict the movement of the beam about the longitudinal axis of the column. The second hinge joint may be configured to restrict angular movement of the beam about the longitudinal axis of the column. The second hinge joint may be configured to restrict angular movement of the beam about the longitudinal axis of the column to a maximum angle of 90 degrees. In other words, the second hinge joint may be configured such that the beam may not be able to pivot about the longitudinal axis of the column by an angle greater than 90 degrees. The second hinge joint may be configured to restrict angular movement of the beam about the longitudinal axis of the column to a maximum angle of 60 degrees. The second hinge joint may be configured to restrict angular movement of the beam about the longitudinal axis of the column to a maximum angle of 45 degrees. This may prevent excessive relative motion of the beam with respect to the column in order to minimise any damage and reduce any resulting excessive misalignment of the overhead power cable over the mining vehicle haul road or track. The second hinge joint may be releasably securable to the column. The second hinge joint may be releasably securable to the beam. The first hinge joint and the second hinge joint may be formed as a biaxial hinge joint. The beam may be coupled to the column via a biaxial hinge joint. The biaxial hinge joint permits pivoting or angular movement of the beam about two axes. The biaxial hinge joint may prevent rotation of the beam. The biaxial hinge joint may be releasably securable to the column and / or the beam. The biaxial hinge joint may be adjusted easily to level the beam compared to the known prior art, whereby the beam is fixed relative to the column. As such, the biaxial hinge joint may reduce installation times and costs. In a steady-state position, the beam may be substantially orthogonal to the column. In other words, the beam and the column may be substantially perpendicular to each other. The beam may be pivotable such that it only moves from a steady-state position towards the second end of the column and back to the steady-state position. In other words, the beam may be coupled such that it does not pivot or move from the steady-state position towards the first end of the column. Advantageously, this ensures that any necessary clearance or distance between the beam and the overhead power cable is maintained. The trolley-assist system may further comprise support means configured to support the beam when in the steady-state position. The support means may advantageously assist in ensuring the beam does not pivot or move from the steady-state position towards the first end of the column. In other words, the support means may restrict movement of the beam in a particular direction. The support means may be configured to be in tension when the beam is in the steady-state position. This may ensure that the beam always returns to the steady-state position as a resting position. The support means may further comprise at least one tensioning cable. The at least one tensioning cable may be configured to further support the beam, which may be cantilevered. The support means may comprise at least one tensioning strut. A first end of the support means may be coupled adjacent the second end of the column and a second end of the support means may be coupled proximate the second end of the beam. The support means being coupled in this manner, in particular, to the second end of the beam minimises the tension required to prevent the beam for pivoting below the steady-state position. Where the support means comprises more than one tensioning cable, the first end of each tensioning cable may be coupled adjacent the second end of the column. Each tensioning cable may be coupled at their first ends to the same location adjacent the second end of the column. The second end of each tensioning cable may be coupled to a corresponding location on the beam. In other words, the second end of each tensioning cable may be coupled to a different point of the beam. The or each tensioning cable may be coupled at a first end to the column and at a second end to the beam. The tensioning cable may advantageously ensure the beam does not pivot about the column such that the angle between the second end portion (or top or upper portion above the beam) of the column and the upper surface of the beam exceeds a pre-determined angle. For example, such a pre-determined angle may be about 90 degrees. This may also ensure that the necessary clearance between the beam and the overhead power cable is maintained. In other words, the tensioning cable may ensure that the beam does not bend or deflect downwards, away from the second, top end of the column and towards the mining haul road. The support means may be configured, or further configured, to be in compression when the beam is in the steady-state position. The support means may comprise at least one compression member. The compression member may be coupled at a first end to a portion of the column below the beam. The compression member may be coupled at a second end to the beam. The compression member may comprise at least one compression strut. The compression member may comprise at least one hydraulic compression member. The support means may comprise at least one tension strut or cable and at least one compression member, such as a compression strut or a hydraulic compression member. The support structure may further comprise a mount configured to releasably couple the beam to the column. The beam may be hingedly or pivotably coupled to the mount. The beam may be hingedly or pivotably coupled to the mount such that the beam is pivotable about the axis orthogonal to the longitudinal axis of the column and orthogonal to the longitudinal axis of the beam. The beam may also be hingedly or pivotably coupled to the mount such that the beam is pivotable about the longitudinal axis of the column. The mount may be releasably coupled to the column. The mount may be configured to be slidable along the column. The mount may comprise a clamp assembly for coupling to the column. This advantageously provides a modular support structure, whereby the parts of the support structure can be moved or adjusted independently. This also allows the positioning of the beam with respect to length of the column to be adjusted easily if needed. The mount may support the hinge joint. The mount may support the biaxial hinge joint. The mount may be configured to releasably couple the beam to the column via the hinge joint. The support structure may comprise a bracket coupled to the mount. The bracket may be hingedly or pivotably coupled to the mount. The beam may be coupled to the bracket. The beam may be hingedly or pivotably coupled to the bracket. The beam may be coupled to the mount via the bracket. The bracket may be hingedly or pivotably coupled to the mount such that the bracket is pivotable about the longitudinal axis of the column. The beam may be hingedly or pivotably coupled to the bracket. The beam may be hingedly or pivotably coupled to the bracket such that the beam is pivotable about the axis orthogonal to the longitudinal axis of the column and orthogonal to the longitudinal axis of the beam or bracket. The longitudinal axis of the bracket may coincide with or be parallel to the longitudinal axis of the beam. The mount may be configured to restrict the pivotable or angular movement of the beam relative to the column. The mount may be configured to restrict the pivotable or angular movement of the beam relative to the column to no more than about 90 degrees. The mount may be configured to restrict the pivotable or angular movement of the beam relative to the column to no more than about 60 degrees. The mount may be configured to restrict the pivotable or angular movement of the beam relative to the column to no more than about 45 degrees. The mount may be configured to restrict the pivotable or angular movement of the bracket relative to the column to no more than about 90 degrees. The mount may be configured to restrict the pivotable or angular movement of the bracket relative to the column to no more than about 60 degrees. The mount may be configured to restrict the pivotable or angular movement of the beam bracket to the column to no more than about 45 degrees. The mount may comprise restricting elements that are configured to restrict the pivotable or angular movement of the bracket or beam relative to the column. The beam or bracket may be located between the restricting elements. The restricting elements may be located on either side of the bracket or beam, and may be configured to obstruct the bracket or beam from pivoting further in each direction. Each restricting element may comprise a pin. The present disclosure also relates to a trolley-assist system for mining vehicles. The system may comprise a plurality of bases. The bases may be free-standing reusable bases. The system may comprise a plurality of support structures according to the first aspect. Each support structure may be mounted to a corresponding free-standing reusable base. According to a second aspect of the present disclosure, there is provided trolley-assist system for mining vehicles. The system comprises a plurality of a plurality of bases. The bases are free-standing reusable bases. The system further comprises a plurality of support structures according to the first aspect. Each support structure is mounted to a corresponding freestanding reusable base. Providing a trolley-assist system for mining vehicles according to the second aspect advantageously provides a system which will have a longer lifetime. This is because the beam being pivotable coupled, as defined in the first aspect, allows the support structure to better withstand and accommodate oscillations and forces applied to it. In particular, upward forces that are applied by a mining vehicle travelling along uneven terrain. Therefore, the support structure is less likely to be damaged by these forces compared to known prior art trolleyassist systems. Each free-standing reusable base is configured to support a corresponding support structure. The reusable base ensures the support structure is maintained in a desired orientation and position. The reusable base is free-standing with respect to a support surface. A support surface may be the ground of the mine or the surface of, or adjacent to, a mining vehicle haul road. The system comprising a plurality of free-standing reusable bases advantageously provides a trolley-assist system that is more portable and reusable. This is because the free-standing nature of the base with respect to the support surface, allows the base to be installed and then easily relocated and re-used without the need for detaching the base from the support surface. The support surface may be the ground of the mine or the surface of, or adjacent to, a mining vehicle haul road. As a result, the reusable base can be relocated and placed in a required position during assembly of a trolley-assist system. Once the reusable base is in position, a support structure can then be releasably coupled to the support structure. The present inventors have recognised and appreciated that the terrain of the ground, support surface or mine, and the entry and access roads of the site, can change over time. Therefore, providing a reusable base that fulfils the required function of supporting the support structure of a trolley-assist system while also being capable of being more easily relocated and adjusted, in the event the terrain of the support surface changes, is advantageous. It allows for a trolley-assist system that is adaptable and flexible to environmental changes. The portability and reusability of the reusable base is further advantageous because it reduces material waste and costs compared to existing arrangements, whereby at least the foundation block or base member is permanently fixed to the support surface and cannot be reused or relocated. Therefore, in such arrangements, a new foundation base has to be used if the location needs to be adjusted due to changes in the terrain or mining vehicle haul road or if the trolley-assist system requires relocation. The reusable base may not be coupled or attached to a support surface. The reusable base may not be permanently coupled or attached to a support surface. In other words, the reusable base may be configured to rest on a support surface. The trolley-assist system may comprise an overhead power cable. The overhead power cable is electrically conductive. The overhead power cable is configured to provide power (electrical power) to a mining vehicle using the trolley-assist system. The beam of the support structure may support the overhead power cable. The beam may provide a support for the overhead power cable such that the overhead power cable is positioned substantially centrally with respect to a mining vehicle haul road or track. The plurality of support structures may comprise two end support structures and at least one intermediate support structure. The overhead power cable may extend between the two end support structures via the at least one intermediate support structure. The two end structures may respectively be located at the beginning and the end of the trolley-assist system. The length of the trolley line may be increased by increasing the number of intermediate support structures between the two end support structures. The trolley-assist system may further comprise a catenary support or messenger cable configured to be supported by the plurality of support structures. The support cable may extend between the two end support structures via the at least one intermediate support structure. The support cable may be configured to be supported by the beams of the plurality of the support structures. The support cable may be configured to support the overhead power cable. The overhead power cable may be suspended from the support cable. The overhead power cable may be supported below the support cable. The support cable may be configured to support the overhead power cable via dropper cables. The trolley-assist system may further comprise a tensioning system configured to adjust the tension in the catenary support cable. The tensioning system may comprise a pulley coupled to a support structure, preferably coupled to one of the end support structures, and tensioning weights coupled to an end of the catenary support cable. The present disclosure also relates to a method of assembly of a support structure according to the first aspect. The method may comprise positioning the column adjacent a mining vehicle haul road. The method may further comprise pivotably coupling the beam to the column. The method may comprise mounting an overhead power cable for providing electrical power to a mining vehicle to the beam. According to a third aspect of the present disclosure, there is provided a method of assembly of a support structure according to the first aspect. The method comprises positioning the column adjacent a mining vehicle haul road. The method further comprises pivotably coupling the beam to the column. The method comprises mounting an overhead power cable for providing electrical power to a mining vehicle to the beam. The method may further comprise arranging the beam such that the longitudinal axis of the beam is substantially parallel to the haul road when in the steady-state position. This may advantageously ensure the necessary clearance is maintained between the beam and the haul road. The method may further comprise arranging the beam such that the longitudinal axis of the beam is substantially orthogonal to the haul road when in the steady-state position. Positioning the column may comprise levelling the column with respect to a support surface. This advantageously ensures the column is in the desired orientation with respect to the support surface. This may involve levelling a reusable base with respect to a support surface. The column may be positioned such that it is substantially vertical. The present disclosure also relates to a mining hauling system. The mining hauling system may comprise a trolley-assist system according to the second aspect and at least one mining vehicle. According to a fifth aspect of the present disclosure, there is provided a mining hauling system. The mining hauling system comprises a trolley-assist system according to the third aspect of the present disclosure and at least one mining vehicle. The mining vehicle may comprise a mining haul truck. The mining haul truck may be configured to draw power from the trolley-assist system, in particular the overhead power cable. The mining vehicle may comprise a power drawing element for drawing electrical power from the overhead power line of the trolley-assist system. The power drawing element may comprise a current collector. The power drawing element may comprise a pantograph. The payload or hauling capacity of the mining vehicle may be at least 50 tonnes. The payload or hauling capacity of the mining vehicle may be at least 100 tonnes. The mining vehicle may be a hybrid vehicle. The mining vehicle may comprise a hybrid powertrain. The mining vehicle may comprise a diesel-electric powertrain. It will be appreciated that features described in relation to one aspect of the present disclosure may also be applied equally to all of the other aspects of the present disclosure. Features described in relation to the first aspect of the present disclosure may be applied equally to the second aspect of the present disclosure and vice versa. For example, features of the support structure described in relation to the first aspect may be applied, mutatis mutandis, to the trolley-assist system of the second aspect. It will further be appreciated that particular combinations of the various features described and defined in any aspects of the invention may be implemented and / or supplied and / or used independently. Detailed Description Specific embodiments of the disclosure will now be described with reference to the figures, in which: Figure 1 shows a side view of a support structure of a trolley-assist system mounted to a freestanding reusable base; Figure 2 shows a magnified perspective view of a biaxial hinge joint coupling a beam to a column; Figure 3a shows a magnified perspective view of a first connection point between a support means and the column; Figure 3b shows a magnified perspective view of a second connection point between a support means and the beam; Figure 4 shows a side view of a trolley-assist system comprising a plurality of reusable bases and support structures Figure 5 shows a flow diagram of a method in accordance with the present disclosure; and Figure 6 shows a flow diagram of a further method in accordance with the present disclosure; Specific Description Figure 1 illustrates a support structure 100 of a trolley-assist system for mining vehicles. The support structure 100 comprises a column 102 and beam 104. The column 102 has a first end which is coupled to a free-standing reusable base 106. The first end of the column 102 comprises a flange 108. The flange 108 is releasably coupled to a corresponding flange 110 of the reusable base 106 via connecting means, such as a plurality of bolts and nuts. As shown in Figure 1, the column 102 is substantially vertical. The reusable base 106 is free-standing with respect to a support surface. The reusable base 106 comprises a reusable base member 112 and a support portion 114. The support portion 114 is offset from the central axis of the base member 112. The support portion 114 is a column. The support portion 114 protrudes from the upper surface of the base member 112. Although not shown, the base member 112 comprises a recess for receiving a first end of the support portion 114. The base member 112 further comprises a reinforcing portion 116. The reinforcing portion 116 extends around a portion of the support portion 114, as shown. The reinforcing portion 116 is integral to the base member 112. The reinforcing portion 116 extends from the upper surface of the base member 112. The reusable base member 112 comprises a plurality of lifting hooks 118. The lifting hooks 118 allow the reusable base member 112 to be picked up, by a crane for example, and positioned in the desired location. Although not shown in the Figures, the reusable base member 112 may be formed of at least two sections. The at least two sections may be coupled to one another via connecting means, such as tie bolts. This advantageously provides at least two sections which are secured to one another when needed, for example, to support the support structure 100, but that can be independently moved and arranged. Because each section can be transported individually, this may reduce the burden on the machinery used to transport the reusable base 106, because the weight will be reduced in comparison to transporting the whole reusable base 106. For example, a 60 tonne (60,000 kg) crane could be used instead of a 100 tonne (100,000 kg) crane that would be required if the base was a single part. Further, as shown in Figure 1, the beam 104 has a first end and a second end. The first end is coupled to the column 102 proximate the second end of the column 102. The first end of the beam 104 is coupled to the column 102 via a hinge joint 120, shown in more detail in Figure 2, such that the beam 104 is pivotable about an axis orthogonal to a longitudinal axis of the column 102 and orthogonal to a longitudinal axis of the beam 104. The beam 104 is arranged such that it is only pivotable, about the axis orthogonal to the longitudinal axis of the column 102 and orthogonal to the longitudinal axis of the beam 104, from a steady-state position towards the second end of the column 102. The beam 104, as shown in Figure 1, is in the steady-state position. As such, in use, the beam 104 is pivotable from the steady-state position towards the second end of the column 102. In other words, the beam 104 can pivot in a direction such that the angle between the beam 104 and the portion of the column 102 above the hinge joint 120 decreases. This allows the support structure 100 as a whole to better withstand forces applied to it from the mining vehicle and / or the overhead power cable bouncing, for example. The beam 104 returns to the steady-state position when no upward force is applied. The support structure 100 comprises support means 122a, 122b which support the beam 104 in the steady-state position. The support means 122a, 122b also prevents the beam 104 from pivoting beyond the steady-state position. In other words, the support means 122a, 122b prevents the beam 104 from pivoting towards the first end of the column 102. The support means 122a, 122b , as shown in Figure 1, comprise two tensioning cables 122a, 122b. A first end of each tensioning cable 122a, 122b is coupled to the second end of the column 102, as shown in more detail in Figure 3. Each first end of the tensioning cable 122a, 122b is coupled to the same point at the second end of the column 102. In particular, each first end of the tensioning cable 122a, 122b is coupled to a bracket 124 secured to the second end of the column 102. A second end of each tensioning cable 122a, 122b is coupled to the beam 104. A second end of each tensioning cable 122a, 122b is coupled to the beam 104 using a bracket 126 that is coupled or releasably coupled to the beam 104. A first one of the two tensioning cables 122b is coupled substantially adjacent the second end of the beam 104. A second one 122a of the two tensioning cable is coupled to the beam 104 about half way along the longitudinal axis of the beam 104. The tensioning cables 122a, 122b ensure the beam 104 only pivots about the axis orthogonal to the longitudinal axis of the column 102 and orthogonal to the longitudinal axis of the beam 104, from a steady-state position towards the second end of the column 102. In alternative examples not shown in the Figures, the support means 122a, 122b is configured, or further configured, to be in compression when the beam 104 is in the steady-state position. The beam 104 supports an overhead power cable of the trolley-assist system (shown in Figure 4). The overhead power cable is the cable that provides electrical power to a mining vehicle. Although not shown, the beam 104 may be coupled to a support cable (shown in Figure 4). The support cable may be coupled to the beam 104 via a connecting means 128. The support cable is configured to support the overhead power cable. The support cable may be configured to support the overhead power cable via droppers and / or hangers 130. In other words, the beam 104 may be coupled to the overhead power cable indirectly via the support cable. A mining hauling system comprises a trolley-assist system comprising a plurality of support structures 100 and at least one mining vehicle 316. As shown in Figure 1, the mining vehicle 316 can be powered by the trolley assist system via a pantograph 318. The pantograph 318 is mounted on the roof of the vehicle 316 to collect power. The pantograph 318 makes contact with the overhead power cable (not shown, but shown in Figure 5). The pantograph may use friction to collect electricity from the overheard power cable. The overhead power cable is coupled to the beam 104 via a plurality of droppers 320. The overhead power cable (not shown, but shown in Figure 5) feeds electricity to the vehicle 316 via the pantograph 318, thereby powering the mining vehicle 316. The support cable is coupled to the beam 104 via a plurality of support elements 322. Although not shown, the support cable provides support to the overhead power cable (see Figure 5). The overhead power cable is suspended from the support cable. Figure 2 illustrates a magnified view of the hinge joint 120. The beam 104 is coupled to the column 102 via the hinge joint 120. The hinge joint 120 is a biaxial hinge joint. The biaxial hinge joint 120 allows the beam 104 to pivot about the axis orthogonal to the longitudinal axis of the column 102 and orthogonal to the longitudinal axis of the beam 104. The biaxial hinge joint 120 may allow the beam 104 to pivot an angle of about 45 degrees. The biaxial hinge joint 120 also allows the beam 104 to pivot about the longitudinal axis of the column 102. The biaxial hinge joint 120 allows the beam 104 to pivot about the longitudinal axis of the column 102 by about 30 degrees. The hinge joint 120 is secured to the column 102 via a bracket 224. The bracket 224 is releasably coupled to the column 102 via a plurality of threaded rods and washers. The biaxial hinge joint 120 is releasably coupled to the bracket 224 via a connecting means, such as a pin 226. The first end of the beam 104 is releasably coupled to the hinge joint 120 via a connecting means, such as a further pin 228. Figure 3a illustrates the first end of the tensioning cables 122a, 122b being coupled to the second end of the column 102. The first end of each tensioning cable 122a, 122b is coupled to a clamp housing 330. The clamp housing 330 is secured to the second end of the column 102 via a bracket 332. Figure 3b illustrates the second end of a tensioning cable 122a, 122b being coupled to a portion of the beam 104. The second end of the tensioning cable 122a, 122b is coupled to the beam 104 via a further bracket 334 that is coupled to the beam 104 via straps 336 and / or bolts. The coupling techniques provided in Figure 3a and Figure 3b are advantageous because they are secure but allow for easy adjustment if needed. As shown in Figure 4, the present disclosure also provides a trolley-assist system 400. The trolley-assist system 400 comprising a plurality of free-standing reusable bases 106, each comprising a reusable base member 112 and a support portion 114. The system 400 comprises a plurality of support structures 100, two end support structures 100a, 100b and at least one intermediate support structure positioned between the end support structures 100a, 100b. Each support structure 100 is mounted to a corresponding free-standing reusable base 106.. Although Figure 4 illustrates three support structures mounted to corresponding freestanding reusable bases 106, the number of support structures 100 mounted to a corresponding free-standing reusable base 106 is dependent on the length of the mining vehicle haul road. The overhead power cable 402 extends between the support structures of the system 400. The catenary or support cable 404, supports the overhead power cable 402 and extends between each support structure 100. The overhead power cable 402 is suspended from the support cable 404 via dropper cables 407. Figure 5 illustrates an example method 500 of assembly of a support structure embodying the present disclosure. The method comprises step 502. Step 502 comprises positioning the column 102 adjacent a mining vehicle haul road. Positioning the column 102 adjacent the mining vehicle haul road comprises positioning a reusable base 106 adjacent the mining vehicle haul road and releasably coupling the column 102 to the reusable base 106. In particular, releasably coupling the column 102 to the support portion 114 of the reusable base 100. The method further comprises step 504. Step 504 comprises pivotably coupling the beam 104 to the column 102. This includes pivotably coupling the beam 104 to the column 102 via the biaxial hinge joint 120. Therefore, step 504 comprises coupling the beam 104 to the column 102 via the biaxial hinge joint 120 such that the beam 104 is pivotable about the axis orthogonal to the longitudinal axis of the column 102 and orthogonal to the longitudinal axis of the beam 104. The method further comprises step 506. Step 506 comprises mounting an overhead power cable 402 for providing electrical power to a mining vehicle to the beam 104. Step 506 may comprise mounting the overhead power cable 402 to the beam via a support cable 404. The support cable 404 be arranged to support the overhead power cable 402. Figure 6 illustrates a further example method 600 of assembly of a support structure embodying the present disclosure. Some of the steps of method 600 are identical to method 500, in particular steps 602, 604 and 606 which are identical to steps 502, 504 and 506. The method 600 further comprises step 605. Step 605 comprises arranging the beam 104 such that the longitudinal axis of the beam 104 is substantially parallel to the haul road when in the steady-state position. Step 605 may further comprise arranging the beam 104 such that the longitudinal axis of the beam 104 is substantially orthogonal to the haul road when in the steady-state position. Steps 502, 602 regarding positioning the column 102 adjacent the mining vehicle haul road may comprise a further step of levelling the column 102 with respect to a support surface. The support surface is the ground. Further, steps 502, 602 may comprise positioning the column 104 such that it is substantially vertical.

Claims

1. A support structure, for a trolley-assist system for mining vehicles, comprising:a column having a first end configured to be coupled to a free-standing reusable base, and a second end; anda beam having a first end and a second end, the first end coupled to the column proximate the second end such that it is pivotable about an axis orthogonal to a longitudinal axis of the column and orthogonal to a longitudinal axis of the beam, the beam being configured to support an overhead power cable of a trolley-assist system for providing electrical power to a mining vehicle,wherein the beam is arranged such that it is only pivotable, about the axis orthogonal to the longitudinal axis of the column and orthogonal to the longitudinal axis of the beam, from a steady-state position towards the second end of the column.

2. The support structure according to claim 1, wherein the beam is coupled to the column via a first hinge joint.

3. The support structure according to claim 1 or 2, wherein the beam is further pivotable about a longitudinal axis of the column.

4. The support structure according to claim 3, wherein the beam is coupled to the column via a second hinge joint.

5. The support structure according to claim 4, wherein the first hinge joint and the second hinge joint are formed as a biaxial hinge joint.

6. The support structure according to any preceding claim, wherein, in the steady-state position, the beam is substantially orthogonal to the column.

7. The support structure according to any preceding claim, further comprising support means configured to support the beam when in the steady-state position.

8. The support structure according to claim 7, wherein the support means is configured to be in tension when the beam is in the steady-state position.

9. The support structure according to claim 8, wherein the support means comprises at least one tensioning cable.

10. The support structure according to claim 8 or 9, wherein the support means comprises at least one tensioning strut.

11. The support structure according to any of claims 7 to 10, wherein a first end of the support means is coupled adjacent the second end of the column and a second end of the support means is coupled proximate the second end of the beam.

12. The support structure according to any of claims 7 to 11, wherein the support means is configured, or further configured, to be in compression when the beam is in the steady-state position.

13. The support structure according to claim 12, wherein the support means comprises at least one compression strut.

14. The support structure according to any of the preceding claims, further comprising a mount configured to releasably couple the beam to the column.

15. A trolley-assist system for mining vehicles comprising:a plurality of free-standing reusable bases; anda plurality of support structures according to any of the preceding claims, wherein each support structure is mounted to a corresponding free-standing reusable base.

16. A method of assembly of a support structure according to any of claims 1 to 14, comprising: positioning the column adjacent a mining vehicle haul road;pivotably coupling the beam to the column; andmounting an overhead power cable for providing electrical power to a mining vehicle to the beam.

17. The method of assembly according to claim 16, further comprising arranging the beam such that the longitudinal axis of the beam is substantially parallel to the haul road when in the steady-state position.

18. The method of assembly according to claim 17, further comprising arranging the beam such that the longitudinal axis of the beam is substantially orthogonal to the haul road when in the steady-state position.5 19. The method of assembly according to claim 16, 17 or 18, wherein positioning the columncomprises levelling the column with respect to a support surface.

20. The method of assembly according to claim 16, 17, 18 or 19, wherein the column is positioned such that it is substantially vertical.

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