Suspension system for a ski vehicle

Abstract

The present invention discloses a ski vehicle comprising a seat 8 with a foot rest 16 connected to an interchangeable suspension system 3 to allow the user to adjust the suspension dynamics to match t

Description

The present invention relates to a ski vehicle (also known as a para-ski, adapted ski, adaptive ski, sit-ski or mono-ski) with an interchangeable suspension system to allow the user to adjust the suspension dynamics to match their skiing / sliding preferences, desired descent characteristics, and disability. US20100109267A1 discloses a ski vehicle for traveling along a surface. The ski vehicle includes a frame comprising a seat supporting member; a steering column rotatably coupled to the frame; a front ski, coupled to the steering column; a rear ski, coupled to the frame, the front and rear skis for supporting the ski vehicle on the surface; and a seat, coupled to the seat supporting member of the frame, for supporting a rider, the seat supporting member of the frame having sufficient length to allow a ski lift chair to slide thereunder. The ski vehicle has a minimum design rider weight, and the weight distribution of the vehicle is selected so that the vehicle is secured on the ski lift chair when the seat is slid over the chair and a rider of at least the design rider weight is sitting on the seat. The ski vehicle may also have a rear swing-arm having first, second and third corners, the first corner movably coupled to the frame and the second corner pivotably coupled to a pivot point on the frame such that the swing-arm pivots about the pivot point when the first corner is moved. The rear ski may be coupled to the rear swing-arm. US20160144882A1 discloses a para-alpine ski, typically a dual-runner sit-ski, has a seat and undercarriage that a user / skier can—under no force(s) save his / her own—cause to raise to a height sufficient so as to permit boarding—totally unassisted if needs be—of the user-skier and his / her entire para-alpine ski onto a moving carry chair of a standard ski-slope chair lift. Upon disembarking the ski slope chair lift, the user-skier can lower his / her seat for skiing, again without assistance. When the same sit-ski is used to ferry a total invalid , then a trained instructor or guide who normally stands at, and steers from, the back of the sitski can stand alongside the sit-ski and its occupant at the point of loading the chair lift, and can trigger the sit-ski seat and its occupantto rise, again permitting that the chair of a standard ski-slope chair lift may be adroitly mounted. The current designs of sit-skis only use a fixed suspension unit (shock absorber) that cannot be changed for another suspension unit. They also do not allow for a change of height of the sit-ski by changing a component of the entire suspension unit system (the suspension unit system is made up of the upper suspension mount / shock linkage, the suspension unit, the lower suspension unit mount and all related attaching components). The present invention allows users to choose the suspension unit that works best for their skiing ability and their disability. It allows users to choose a suspension system that can be changed easily. Furthermore, it also allows users to select a suspension set-up that not only suits their needs and skiing ability, but matches the intended style of skiing or terrain they intend to ski on, such as off-piste skiing or freestyle skiing. The secondary function of changeable suspension unit mounts is that the height of the sit-ski frame and therefore the height of the skier's position (the height from the surface of the snow to the skier in the seating position) can be changed without necessarily changing the suspension unit or shock absorber. Different shaped suspension unit mounts can provide a change in overall height since the ski vehicle's frame is suspended and relies on the reactionary force of the suspension unit to stop it from collapsing. Embodiments of the invention can include the following components: a. The deck: this section runs almost laterally and supports the weight of the skier. The seat, footrest, uprights, and the upper shock absorber mounts are all attached to the deck. b. Upper suspension system linkage / upper mount: this part links the deck to the suspension directly or via a separate upper suspension mount. It allows the sit-ski some vertical movement so that it can reach the required height to access a ski chair lift. The present invention offers different shapes and sizes of the shock linkage unit / upper suspension mount to match the intended suspension unit choice by the user. c. Lower suspension system mount / lower mount: this part can be provided in a range of different shapes and sizes with different mounting hole characteristics and allow for different sizes and performance of suspension unit or shock absorber to be mounted correctly within the sit-ski frame. d. The suspension unit or shock absorber: in general, the suspension unit or shock absorber is attached to the sit-ski frame at each end via an upper mount and the lower mount. This part is manufactured by a third-party and can be changed as mentioned above. e. The base / block: this part is the base of the ski that fits directly into the binding of the ski. It also provides the lower attachments of the four uprights. Furthermore, it also provides a surface for the lower suspension unit mount to be located and attached in a range of positions. Fixing components (bolts, bushings, bearings, washers, nuts etc.): these provide of all the attachments required to assemble both the range of suspension systems and the sit-ski in general. These parts are made by third-party manufacturers and the components work in the following exemplary manner. The base sits within the bindings attached to the ski vehicle. From the base, the uprights are attached via bearings and bolts to create a pivot on each upright at the point where it attaches to the base. Also attached to the base is the lower shock mount which is fixed to the base via attachments (e.g. bolts). It can be moved into different positions depending on what the user requires. Furthermore, there are a range of lower shock mounts that can be fitted to the base, all via the same attachment process. From the lower suspension unit mount, the suspension unit or shock absorber is connected via a pivot involving bushings and bolts. At the top of the suspension unit or shock absorber is the upper suspension system mount. The connection between the top of the shock absorber and the upper suspension system is pivotable via bushings and bolts. Furthermore, there are also a range of upper mount options, and they are interchangeable depending on the suspension unit or shock absorber chosen by the sit-skier. The upper suspension unit mount is connected to the main deck of the ski via nuts, bolts and bearings. The user can choose an 'off the market' suspension unit or shock absorber that matches their requirements. For example, they might choose a motorcycle shock or a downhill mountain bike shock. Due to the different sizes, both in length, diameter and compression strength of different suspension units or shock absorbers along with the different eyelet diameters and overall shape, it is therefore necessary to supply a range of upper and lower suspension unit mounts that can universally fit the frame of the sit-ski but independently fit the desired choice of suspension unit or shock absorber. Therefore, both the lower mount and upper mount are designed in kits that will fit an individual brand of suspension unit or shock absorber. The secondary feature and function of the invention is that the height of the ski vehicle can be adjusted via a change in the suspension unit mounts but not necessarily changing the suspension unit or shock absorber. The ski vehicle frame is pivoted in a parallelogram and uses the reactionary force of the suspension unit to stay at a specific height. Since the suspension system is made up of three major components (the upper mount, the suspension unit and the lower mount), then changing just one of these components' shape or size can adjust the skiing height of the entire ski vehicle. The mounts take into account the length, width, compression force and eyelet size of the suspension shock absorber. The mounts are not limited to one material and are engineered and designed to suit the choice of shock absorber that the skier chooses but universally attach to the base of the ski vehicle and to the upper deck of the ski vehicle. The present invention can be made from different materials that suit the shape of the different mounts and the intended forces that will run through them. Aluminium alloy, steel alloy, magnesium alloy, titanium alloy, carbon fibre composite, glass re-enforced plastic, PETG plastic, nylon, Kevlar, PTFE or a plastic alloy could be selected as a material for the mounts. The present invention can be used in the following manner: 1. the user supports the frame of the ski vehicle so it will not collapse when the shock is removed; 2. once supported, the user with a tool can loosen the bolts that hold the upper mount or shock absorber to the frame (the upper mount and the shock absorber are one and the same or are two parts); 3. the user again using a tool can loosen fully the bolts that support the lower mount to the base; 4. now the user can remove the whole suspension system in one, that includes the lower mount, the shock absorber and the upper mount (these three pieces can be removed separately or as one piece attached together); 5. the user then chooses their desired suspension unitor shock absorber and selects the appropriate lower and upper mounts that match specific dimension of suspension unit; 6. the user now reverses the process with the new self-selected suspension unit and mounts. Attaching, via tools, the lower mount, the upper mount and suspension unit; 7. the user carries out basic mechanical testing to ensure that the movement of the ski vehicle frame and suspension unit is working as desired, and bolts are sufficiently tightened so that the ski vehicle is ready to use. The advantage of the present invention is that it can be used in a range of different sporting devices and vehicles. Any sporting equipment or vehicle using a suspension unit or shock absorber could utilize an interchangeable suspension unit to match the requirements of the user and the intended use of the equipment or vehicle e.g. in a variety of terrain choices, on road, off road, snow, forestry track, downhill mountain bike track, BMX style park. It can also be used for mountain bikes, motorbikes, motocross, cars, off-road vehicles, all-terrain vehicles (ATVs), vehicles carrying different loads throughout their use, wheelchairs, mobility scooters, electronic scooters, scooters, snowmobiles. According to embodiments of the present invention, there are provided sit-ski suspension systems as described in the claims. The invention may be produced in various ways and embodiments thereof will now be described, by way of example only, reference being made to the accompanying drawings, in which: - FIGURE 1 depicts an exemplary ski vehicle, in a side view; FIGURE 2 depicts the ski vehicle of Figure 1, in a perspective view; FIGURE 3 depicts the ski vehicle of Figure 1, in a rear view; FIGURE 4 depicts the ski vehicle of Figure 1, with the legs (uprights) removed, in a side view; FIGURE 5 depicts an interchangeable suspension system for a ski vehicle according to an embodiment of the invention, including a shock absorber / suspension unit in a side view, with upper mount and lower mount attached; FIGURE 6 depicts the interchangeable suspension system for a ski vehicle of Figure 5 in a perspective view; FIGURE 7 depicts an interchangeable suspension system for a ski vehicle according to an embodiment of the invention, including a shock absorber / suspension unit in perspective view attached to the base via a universal footprint attachment; FIGURE 8 depicts an interchangeable suspension system for a ski vehicle of according to an embodiment of the invention, in an exploded perspective view; FIGURE 9 depicts the attachment of legs (uprights) of a ski vehicle base, in exploded perspective view; FIGURE 10 depicts an example of a lower mount and its attachment to a universal footprint of the base; FIGURE 11 depicts an example of an upper mount option and its attachment to a universal footprint of the deck; FIGURE 12 depicts examples of commercially available shock absorbers / suspension units, in side view; FIGURE 13 depicts examples of upper mounts (shock linkages), in side view; FIGURE 14 depicts examples of lower mounts (shock linkages), in side view; FIGURE 15 depicts various interchangeable suspension systems for a ski vehicle according to embodiments of the invention; wherein different suspension units / shock absorbers are attached to corresponding upper mounts / shock linkages and lower mounts in a perspective view. Additionally, two 'rigid suspension systems' are shown, where the lower and upper mounts are designed as one monocoque rigid unit spanning from the base to the deck; FIGURE 16 depicts various interchangeable suspension systems for a ski vehicle of Figure 15, in side view; FIGURE 17 depicts an interchangeable suspension system for a ski vehicle of according to an embodiment of the invention, with the legs and base removed; FIGURE 18 depicts an interchangeable suspension system for a ski vehicle according to an embodiment of the invention with the near side (left side) legs removed, the lower mount removed and the base removed; FIGURE 19 depicts an interchangeable suspension system for a ski vehicle according to an embodiment of the invention, with the upper mount removed and attached to the base and said base attached within the ski and bindings; FIGURE 20 depicts an interchangeable suspension system for a ski vehicle according to a first exemplary embodiment of the invention and its effect on the skier's position in relation to the height from the ground and position over the front of the ski; FIGURE 21 depicts an interchangeable suspension system for a ski vehicle according to a second exemplary embodiment of the invention and its effect on the skier's position in relation to the height from the ground and position over the front of the ski; FIGURE 22 depicts an interchangeable suspension system for a ski vehicle of according to a third exemplary embodiment of the invention and its effect on the skier's position in relation to the height from the ground and position over the front of the ski; FIGURE 23 depicts an interchangeable suspension system for a ski vehicle of according to a fourth exemplary embodiment of the invention and its effect on the skier's position in relation to the height from the ground and position over the front of the ski; FIGURE 24 depicts an interchangeable suspension system for a ski vehicle of according to a rigid suspension embodiment of the invention and its effect on the skier's position in relation to the height from the ground and position over the front of the ski; FIGURE 25 depicts a base for a ski vehicle for use with an interchangeable suspension system according to an embodiment of the invention, in perspective view; FIGURE 26 depicts a base for a ski vehicle for use with an interchangeable suspension system according to an embodiment of the invention, in side view; FIGURE 27 depicts a base for a ski vehicle for use with an interchangeable suspension system according to an embodiment of the invention, in front view; FIGURE 28 depicts a base for a ski vehicle for use with an interchangeable suspension system according to an embodiment of the invention, in top down view; FIGURE 29 depicts a base for a ski vehicle for use with an interchangeable suspension system according to an embodiment of the invention, in a second perspective view; FIGURE 30 depicts a lower mount of an interchangeable suspension system according to an embodiment of the invention, in perspective view; FIGURE 31 depicts a lower mount of an interchangeable suspension system according to an embodiment of the invention attached to a base of ski vehicle, in perspective view; FIGURE 32 depicts a lower mount of an interchangeable suspension system according to an embodiment of the invention, in top down view; FIGURE 33 depicts a lower mount of an interchangeable suspension system according to an embodiment of the invention, in a second perspective view; FIGURE 34 depicts an upper mount of an interchangeable suspension system according to an embodiment of the invention, in perspective view; FIGURE 35 depicts an upper mount of an interchangeable suspension system according to an embodiment of the invention, in side view; and, FIGURE 36 depicts an upper mount of an interchangeable suspension system according to an embodiment of the invention, in top down view. With reference to Figures 1 to 4 there is shown a sit-ski type ski vehicle comprising a base 1 connected to a ski 15 by a binding 13. Various types of ski and bindings are well-known to the person skilled in the art. The base 1 comprises a portion of a "universal mounting" (described in relation to Figures 9 to 11) feature, lower mount 2 also includes a portion of the "universal mounting" feature, by which the base and lower mount are detachably connected. The "universal mounting" allows for multiple types of base and lower mount to be connected and in different position to suit the specific needs of the skier and suspension equipment (shock and links) being used. An upper mount 4 (shown in Figure 4) also includes a "universal mounting" feature, by which it is connected to a deck 5 also including a portion of the "universal mounting". A shock absorber 3 is shown removably connected between the upper mount 4 and lower mount 2, the mount may be formed with specific connection features to receive specific shock absorbers. All mounts according to the claimed invention are formed with the universal mounting required to detachably engage with corresponding mountings on the deck 5 and base 1. Also shown in Figure 1 are the sit-ski seat (8) and "uprights" (6,7) pivotably connecting the deck to the base. The interchangeable suspension system in its entirety fits within the frame of the sit-ski and is critical to the good functioning of the sit-ski. The user can make use of the invention by removing and reinstalling different elements to gain the required performance from their sit-ski. Simple tools allow the user to unbolt the lower mount 2 from the base 1 and the upper mount 4 (upper linkage) from the deck 5. Furthermore, the user can detach the suspension unit 3 from the mounts 2,4 via a bolt and bushing assembly or other suitable connection means. Then another set of mounts and suspension unit can be reattached via bolting and tools in the same process but reversed. The sit-ski and interchangeable suspension system can be realised in different ways using different materials and designs across all parts and their variations that suit the desired suspension choices and preference of the skier. Starting with the base and moving upwards; this could be produced from an aluminium alloy block. It could be designed so the dimensions and shape fits into normal ski binding. A computer numerical control (CNC) milling process or a manual milling process could achieve the realisation of this shape from aluminium alloy. The base 1 includes axle points front and rear to support the front legs 7 and rears legs 6 respectively. The rear legs could be attached to the rear axle to form one unit in regard to their operation. The front legs are attached to the front axle. The aluminium base could be drilled side to side both at the front and the rear. The insertion of a PTFE (polytetrafluoroethylene) tube into the base would become the outer bearing surface, the rear or front legs would have an axle attached that would insert through the PTFE tube. A shouldered steel bolt could then be inserted through the centre of the rear / front leg assembly and the base and consequently bolted the other side. The axles and therefore the legs can thus rotate freely in respect to the base. Incorporated in the design of the upper side or face of the base 1 is a mounting surface for the lower mount 2. The invention covers a range of suitable lower mounts each with the same universal footprints. A large range of lower and upper shock mounts exist, which are not limited to one size, material or design but rather can suit the needs of the skier's shock selection and skiing preferences. In an example the lower mount 2, locates on the top surface of the base 1. Three in-line holes that are drilled into the base mounting surface at a perpendicular orientation to the surface and are consequently threaded. The lower mount is located on to the base in line with the three threaded holes in the base. A set of three bolts with washers then run through the lower shock mount into the base, they can be tightened to securely gain a firm and solid connection of these two parts. One way in which the lower mount can be constructed is by pre-drilling sheet metal such as chromoly steel (steel alloy) and bending the strip of chromoly steel twice along its width. The consequent shape would be that of a U. Then predrilled holes would line up left to right to which the axle and lower end of the shock absorber 3 (suspension unit) can be mounted. Third party manufactured parts or 'off the shelf' parts can provide a bearing / bushing surface along with a shouldered bolt as an axle for the joint of the lower mount 2 with the shock absorber / suspension unit 3. The components such as shouldered bolts and nuts could be utilised as the attaching components for these bearings. Both ends of the shock absorber / suspension unit 3 can connect to the upper mount 4 and lower mount 2 using this set up. The shock absorber or suspension can thus rotate freely in a perpendicular plane to that of lower and upper mount. The upper end of the shock absorber connects to the upper mount 4. In specific embodiments the shock and upper mount can be a singular rigid unit. However, in other embodiments the upper shock mount could be made of two or more moving parts. This would allow the sit-ski seat and deck to lift in height to permit the user to utilise chairlifts (a common form of ascending a mountain side in a ski resort). In this case, the upper mount and linkage include a suitable opening that has been manufactured with axle holes to mount the shock absorber. Third party manufactured axles and bushings could then securely attach the shock. The upper side of the upper shock mount / shock linkage can have predrilled holes that allow bolts and washers to be located so it can be attached to underside of the deck. Each design of the upper shock mount / shock linkage uses universal dimensions to mount it to the underside of the deck thus allowing interchange of different upper shock mounts / shock linkages to be performed by the user or designated mechanic for the sit-ski. The fabrication of the upper shock mount / shock linkage may be manufactured using a high-grade, 3D-printed nylon or nylon / carbon fibre alloy, making use of computer aided design (CAD) to design the shape for the 3D printer slicer program. The slicer sends the correct coding to the 3D printer to perform the additive manufacture of this part. The deck can be fabricated through a matrix of aluminium alloy tubing and aluminium alloy plate welded together. The under-plate section of the deck has pre-drilled through holes to accept the location of the upper shock mount / shock linkage. Third party or 'off the shelf' bolts, washers and nuts would be used to attach the parts with standard workshop tools. This interchange could be performed by the user of the ski or his / her designated mechanic, in some cases this could be the ski instructor. The deck has pre-drilled holes within the flanks to allow ceramic bearings to be fitted via an interference fit. The front and rear legs with their respective axles are and attached to the deck with shouldered bolts and internal threads that are prefabricated in the aforementioned plated flanks of the deck. In addition, the sit-ski features a footrest, bucket style seat and respective straps for the user to secure themselves to the sit-ski. The deck can have locating holes predrilled in plate aluminium alloy for a pre-bent steel footrest to be attached. A range of different bucket seats of different shapes and sizes can be attached to the deck via bolts and nuts. The seats could be manufactured in Acrylonitrile Butadiene Styrene (ABS) plastic via injection moulding. In addition, there may be further pre-drilled holes in the structure of the deck to allow for a range of strapping locations for the user to choose where to locate straps that support their feet, lower legs, upper legs (lap strap) and chest. With reference to Figures 5 and 6 there is shown an exemplary interchangeable suspension system comprising the three principal elements of the lower mount 2, the suspension unit 3 and the upper mount or upper shock linkage 4. These elements are interchangeable depending on the desires of the user and the requirement they might have; such that different construction of each element can be used in conjunction with one another. The mounts (upper and lower) are generally specific to each suspension unit as each suspension unit has a range of characteristics, however it is also possible that a change of just the lower mount can deliver the desired effect for the characteristics of the sit-ski and in the right circumstances i.e. when the suspension units are similar in design this could also be possible. Detaching and attaching to the sit-ski frame; the ability to remove the suspension system is done so via detaching the upper and lower mounts 3,4 in any order. The upper mount 4 is removed from the deck 5 via unscrewing the coupling member e.g. the four bolts 21 which couple themselves into the deck. Similarly, the lower mount attaches to the base 1 in a similar fashion. Removal is carried out by unscrewing the bolts 20 and the lower mount comes away from the base. In this example, the upper mount 4 has a hinged pivot and an aluminium body that suits the needs of this suspension characteristics. In all cases, the installation of new mounts and suspension have similar connection configurations (universal mounting system) which may comprise bolt placements, diameters, thread pitch and allow any number of upper and lower mounts to fit the base and deck respectively via a universal design of attachments. With reference to Figures 7 and 8 in this example, a suspension unit 3 or shock absorber connects to the upper mount 4 and lower mounts 2 by similar sized holes in both the suspension unit and the mount. The suspension unit 3 has a lower end connecting means 50 which is lined with a lower mount bushing 45 for example, with 10mm internal diameter. Likewise at the connecting means 51 at the upper end the suspension unit is aligned with an upper mount bushing with the same internal diameter of 10mm. A shouldered bolt 17,18 with a diameter to suit the internal bushing diameter is pass through both mount and end hole of the suspension unit. However, washers 32,40 are placed between these parts across the bolt to avoid rubbing and aid freedom of rotational movement. The shouldered bolt and bushing assembly provide a wear resistant, single plane of rotation joint between the mounts and the suspension unit. To complete the assembly a nut 35, 33 and further washers are added at the end of the shouldered bolt to ensure that the assembly stays together, and no lateral movement of the bolt can take place. With reference to Figures 9 and 10 there is shown an example of the attachment of the lower mount 2 to the base 1. In the example the base has a universal set up or footprint of pre-threaded holes 43 that allow the attachment of the lower mount 2 via bolts 41 of the same size thread and depth. The lower mount 2 sits on top of the base 1 and is removed or installed by running threaded bolts through holes in the base of the lower mount and tightening them into the base footprint, washers 42 sit on the bolts 41 to prevent marking the material of the lower mount, and also spreading the load of the bolts 41 around the holes of the lower mount 2 to prevent cracking. To carry out the tightening or loosening of the bolts, then simple tools can complete this task - the user or mechanic could use a spanner (crescent wrench) or Allen key (hex key wrench) or a combination of the two. The example in the figures uses hexagonal ended bolts but the embodiment may use other headed bolts such as cap screw Allen head bolts. With reference to Figure 11, there is shown an example of the upper mount 4 connecting to the deck 5 in a universal way, allowing a range of upper mounts to be attached to the underside of the deck 5. A uniform design across all upper mounts attaching surface means that threaded bolts 37 can run through the attaching surface and into pre-threaded holes 39 in the underside of the deck that have this universal footprint of holes to allow the interchange of mounts. Washers are used between the bolts 37 and upper mount to stop marking and spread loads across the hole entry. In this example 4 bolts in a square formation are used to attached to the same formation in the underside of the deck, whilst not limited to this design, any mounting means according to the invention will allow the interchange of varied mounts on to the same deck 5. In this example simple tools such as spanner (crescent wrench) and Allen key (hex key wrench) could be used to loosen bolts, remove the mount and replace the desired mount. With reference to Figures 12 and 16 there are examples of an array of suspension units (Figure 12), upper mounts (Figure 13), lower mounts (Figure 14) and interchange suspension systems (Figures 15,16) that could be fitted in to the sit-ski frame by the user, mechanic or instructor. Each example demonstrates the variance in suspension units 3,3' and thus the varied designs of the lower mounts 2 and the upper mounts 4. Once the user has selected their desired suspension system, then they can attach one of these systems into the sit-ski frame with tools. The rigid bars 3', attach in much the same universal way, the lower end on to the base 1 and the upper end on underside of the deck 5. These have been illustrated here as two possible embodiments or options for a sit-skier who wishes to have a rigid sit-ski at certain height. Unlike the suspension units themselves which are commercially available devices these rigid bars 3' are a unique design. With reference to Figures 17, 18 and 19, show various stages of construction / deconstruction of an interchangeable suspension system for a ski vehicle according to embodiments of the present invention. With reference to Figures 20 to 24, there are shown various complete embodiments of an interchangeable suspension system for a ski vehicle according to the present invention, showing the ability to alter the vehicle dynamics but maintain the simplicity of adapting the vehicle due to the universal nature of the interchangeable suspension system. Specifically Figure 20 demonstrates an option where the sit-skier is able to select a set-up that gives a higher skiing height position in relation to the skier and the ground. In addition, a more upright body position is achieved, and the skier has a smaller, stiffer suspension unit with less travel. As an example, this setup would perhaps suit a beginner or someone with poorer mid body core strength. The terrain and style of skiing would suit well-maintained, on-piste slopes, and the style of linked small turn skiing (commonly referred to as linked parallel turns in able-bodied skiing). Specifically Figure 21 demonstrates an option where the user has selected a suspension system that has increased the height of the sit-ski via a long suspension unit 3. The mounts 2,4 are of low profile and thus all the relevant height gain is in the suspension shock unit 3. This set up has a higher skiing height in relation to the snow. The large suspension travel, increased dampening and rebound would suit a bumpy terrain or a terrain involving tricks, such a terrain as a mogul field or snow park would be recommended. Specifically Figure 22 demonstrates an option where the ski frame would suit an all-rounder or polyvalent style of skier or perhaps a good benchmark for persons who have poor core strength. This set up sees the ski height as mid-level, the seat position at rear to mid-level and the suspension unit of similar mid-level performance. A standard sized mountain bike coil suspension unit is used here and thus provides the most cost-efficient option. Specifically Figure 23 demonstrates an option where there is a shorter suspension unit 3 and corresponding mounts 2, 4. The seating position is lower and also further forward over the ski. This dynamic change in position alone would be preferable for racing and the small shock suited to a groomed piste where the impact forces are low. Specifically Figure 24 demonstrates an option where the suspension system is entirely rigid and one single part 3, bringing together the lower mount 2, upper mounts 4 and associated joining components in to one entity. This example of a long rigid system provides the user an option to raise the height of the skiing position and to focus on aspects of their technique that isolate skiing without the use of the suspension. In addition, this option would be recommended for those who do not experience back pain with their injury or disease. With reference to Figures 25 to 29, there is shown an alternative example of the base 1, showing the flat attaching area for the lower mounts 2. This flat area combines the use of 8 threaded holes and 6 'male' cylindrical protrusions. Any lower mount can be attached securely to this area, provided it has corresponding holes for threaded bolts to run through. Furthermore, the lower mounts have corresponding 'female' cylindrical cavities to accept the 'male' protrusions on the base mounting surface. These provide extra security once attached, and also a guide when mounting the lower mount. The example has a mounting surface for the lower mount at the front half and two-hole options for the front leg axle to run through, and at the rear there are three holes for the possible location of the rear leg axle to run through. This would be a choice by the skier as to how they want to sit-ski to perform. In this embodiment, suitable materials could be used to achieve the task for which it is intended, including but not limited to ABS, nylon, polyurethane, carbon composite, carbon fibre, glass fibre, could all be acceptable via injection moulding, cold pour moulding / vacuum casting or a fibre lay up manufacturing process. Metals could also be a manufacturing consideration, such as aluminium alloy or titanium alloy or steel alloy and manufactured by a combination of casting, CNC mill, waterjet mill, laser cutting, manual mill or metal 3D printing. Other 3D printed materials could also be a consideration, including but not limited to, nylon, carbon fibre, fibre glass, nylon / carbon composite, ABS, polyurethane (PU), polycarbonate (PC), polyethylene terephthalate glycol (PETG), or PETG composite such as carbon / PETG. In addition fibrous material manufacture such as lay up moulding or vacuum moulding using but not limited to carbon fibre, Kevlar fibre, glass fibre with resins could be equally suitable as a material and manufacturing choice. With reference to Figures 30, 32, 33 there is shown an alternative example of the lower mount 2. On the top surface there is a rectangular pattern of eight holes that are counter sunk. These will accommodate the eight bolts that will run through and thread into the base 1 (Figures 25 to 29) on the base attachment area. Running laterally, from the right side of the lower mount to the left side, near the front, are the mounting holes for the lower suspension pivot axle that connects the lower amount and the suspension unit. These encased holes, have bushings mounted within, in order to accommodate a rotational friction and pressure on the lower suspension pivot axle. The well within the middle of this example accommodates the suspension unit 3. The suspension unit to be used in this example has an air pressure cylinder permanently attached to the side. The well in centre of the lower mount accommodates this both in it stationary position and through the suspension unit's range of rotation experienced when the sit-ski is in use. Furthermore, at the front right-side corner of the lower mount, the design has exposed half of the shaft that houses the front right mounting bolt. This area is to allow adequate space for the air valve that this particular suspension unit has and allows the user to attach an air pump to the suspension unit (to increase or decrease suspension unit pressure) without interference. The underside of the lower mount shown in Figure 33 has eight holes that match the universal attachment area of the base 1 are visible in a rectangular fashion. Also visible in this view are the cavities that match the universal base protrusions thus creating a male to female attachment of the lower mount and the base 1 in addition to the threaded bolts. Figure 31 depicts the lower mount 2 (as shown in Figures 30, 32, 33) couple to the base 1 (as shown in Figures 25 to 29). With reference to Figure 34, 35 and 36 there is shown an alternative example of the upper mount 3. The upper mount has several features, firstly it is a single piece with no moving parts within and no pivoting section (as described in some other embodiments). At the rear of the mount there is a lateral hole that extends through, within this hole sits a metal bushing such as a brass bushing tube. A shouldered bolt runs through the deck, through the upper mount and back through the deck 5. The shouldered bolt has washers placed along its length to stop rubbing between the deck 5 and upper mount. A simple nut and washer can be placed at the end of the shouldered bolt to secure the entire attachment. Similarly to the lower mount, the upper mount can be removed and reinstalled (or other options of the upper mounts). This can be achieved by undoingthe nut on the upper mount axle shouldered bolt and removing it via sliding it out from both the deck and upper mount. The upper mount then becomes free form the deck 5. Two lugs, both symmetrical and placed opposite each other are shown on the right and left side. These acts as a latching location system for the upper mount when the sit-ski is in ski mode. The sit-ski has two modes one of which is the skiing mode and the other being lift assist mode'. Lift assist mode requires that the sit-ski seating area can temporarily gain in height to access a chairlift typical of that found in any ski resort. In this embodiment the upper mount provides an additional function of pivoting and thus providing a temporary gain in height for seating area of the sit-ski. At the front of this embodiment is shown the attachment area consisting of two 'forks' for the mounting of the top of the suspension unit 3 which may be an eyelet. The gap in the centre of the mount between the forks is sufficiently wide enough for the upper eyelet of the suspension unit and is of adequate width to allow the suspension unit features to be accommodated and to move freely in a rotational plane. The attachment to the eyelet in top of the suspension unit is via an 10mm diameter shouldered bolt through bushings of internal diameter of 10mm in the eye of the suspension unit. There are also bushings with a 10mm internal diameter within each side of the front 'forks' of the upper mount. A shouldered bolt is passed through both the upper mount forks and the upper eyelet of the suspension unit. Washers are placed along the length of the bolt and a nut is used to secure the bolt. Not all suspension units use an eyelet style connection system, thus this is another reason why a range of embodiments of the upper mounts is included within the scope of the invention. On the top side of the upper mount there is a raised semi spherical dome. This sits with in a female counterpart cavity on the underside of the deck 5 and ensures that when the sit-ski is in ski mode that it is seated correctly. The present invention overcomes the problems of the prior art by providing an interchangeable suspension system. The features described in the foregoing description, or the following claims, or the accompanying drawings may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof. Index 1 - base 2 - lower mount 3 - suspension unit / shock absorber 3' - rigid suspension 4 - upper mount 5 - deck 6, 7 - uprights / legs 8 - ski seat 9, 10 - upright through holes to connect legs to deck 11, 12 - upright through holes to connect legs to base 13 - back-end ski binding 14 - front end ski binding 15 - ski 16 - seat support / footrest 17 - bolt to connect suspension to lower mount 18 - bolt to connect suspension to upper mount 19 - lower mount connect aperture for connecting to suspension unit 20 - lower mount to base connecting bolt 21 - upper mount to deck connecting bolt 32, 37, 38, 40-washer 33, 34, 35 - nut 36 - bolt to connect leg to base 37, 41-bolt 39 - deck pre threaded hole 42 - washer 43 - base pre-threaded hole 44 - lower mount to base connecting aperture 45 - bushing for lower mount connect aperture for connecting to suspension unit 19 46,47 - bushing for bolt to connect leg to base 36 50 - suspension lower end connecting means / eyelet 51 - suspension upper end connecting means / eyelet

Claims

28 03 251. A ski vehicle suspension system comprising:a deck having in use an upper side for receiving a ski seat and a lower side with an upper mount connection area:a base having in use a lower side for connecting to a ski binding and an upper side with a lower mount connection area;an upper mount having at least one deck locating feature for detachably coupling to the upper mount connection area of the deck;a lower mount having at least one base locating feature for detachably coupling to the lower mount connection area of the base;a suspension member having an upper mount coupling means and a lower mount coupling means; and,wherein the upper mount and lower mount each further comprise suspension member coupling means for releasably coupling a suspension member therebetween.

2. The ski vehicle suspension system according to any previous claim, wherein the lower mount connection area comprises an array of mounting elements.

3. The ski vehicle suspension system according to claim 2, wherein the array of mounting elements comprises apertures and protrusions.28 03 254. The ski vehicle suspension system of claim 3, wherein the apertures are located substantially around a perimeter of the lower mount connection area and the protrusions are located substantially central of the lower mount connection area.

5. The ski vehicle suspension system according to any previous claim, wherein the at least one base locating feature comprises an array of mounting features.

6. The ski vehicle suspension system according to claim 5, wherein the array of mounting features comprises apertures and recesses.

7. The ski vehicle suspension system according to claim 6, wherein the apertures are located substantially around a perimeter of the lower mount and the recess are located substantially central of the lower mount.

8. The ski vehicle suspension system according any of claims 2 to 4 and 5 to 7, wherein the lower mount connection area co-locates with the base locating features.

9. The ski vehicle suspension system according to claim 8 when dependent on claims 3 or 4, and, claims 6 or 7, wherein the co-located apertures are configured to receive an affixing means to releasably affix the lower mount to the base and thereby the ski binding.28 03 2510. The ski vehicle suspension system according to any previous claim, wherein the upper mount connection area comprises at least one mounting element.

11. The ski vehicle suspension system according to any previous claim, wherein the at least one deck locating feature comprises a first deck locating feature, wherein the first deck locating feature comprises two laterally extending protrusions either side of the mount and defining a borehole therebetween.

12. The ski vehicle suspension system according to claim 11, wherein the at least one deck locating feature comprises a second deck locating feature.

13. The ski vehicle suspension system according to claim 12, wherein the second deck locating feature comprises a laterally extending channel through the upper mount.

14. The ski vehicle suspension system according to any of claims 11 to 13, wherein the upper mount connection area co-locates with the at least one deck locating feature.

15. The ski vehicle suspension system according to claim 14, wherein the colocated features are configured to receiving an affixing means to releasably affix the upper mount to the deck.28 03 2516. The ski vehicle suspension system according to any previous claim, wherein lower mount suspension coupling member comprises a receiving well to locate the suspension member within a portion of the lower mount.

17. The ski vehicle suspension system according to any previous claim, wherein upper mount suspension coupling member comprises a receiving space to locate the suspension member within a portion of the upper mount.

18. The ski vehicle suspension system according to previous claims 16 and 17, wherein the upper mount coupling means of the suspension member and the lower mount coupling means of the suspension member, co-locate with the receiving well and receiving space, both coupling means, receiving well and receiving space are configured to receiving an affixing means to releasably affix the upper mount and lower mount to the suspension member.

19. The ski vehicle suspension system of any previous claim, wherein the ski vehicle is a sit-ski.

20. A ski vehicle assembly comprising two or more different ski vehicle suspension systems according to any previous claim, wherein the upper mount, lower mount and suspension member are interchangeable between the two or more systems.

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