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On 3 Wheels Everyday

By Melvin Hunt,2014-05-12 17:26
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On 3 Wheels Everyday

    ON 3 WHEELS EVERYDAY MEETING THE CRITERIA OF

    REMOTE AUSTRALIAN WHEELCHAIR USERS.

    Stephen Hales, ILC Queensland.

Abstract.

    In recent years several wheelchair users in remote Australia have been fortunate enough to find funds for costly beach wheelchairs. Some products have seen very little use however; the author observing a new chair disassembled and packed away in a cupboard covered in cobwebs, while the wheelchair user moved about the sandy area outside his home in his everyday wheelchair. This paper reviews trials of the prototype WorldMade 3 wheel rural wheelchair made by the UK based development organisation Motivation. Designed for the needs of less well financed wheelchair users in rural areas in developing countries, the wheelchair is individually assembled to size for the user in a regional location, providing an efficient base for manual mobility, with provision for skin care and seating needs. The prototype was trialled across a wide range of terrain and wheelchair user activity levels. A restricted choice of rear wheel and castor options was trialled to meet different environment extremes and budgets. The effectiveness of the one design to provide for diverse user needs and environments is discussed in reference to the challenging criteria for an everyday wheelchair in remote Australia.

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    Wheelchair users in remote Australia face numerous challenges in obtaining appropriately designed wheelchairs, as raised in some earlier discussions (ILC WA 1994, Hales 2001, Hales & Sloane 2001).

    Local manufacturers and suppliers considering importing new designs need confidence that a new product can be viable, which translates to a certain level demand from the market of wheelchair users.

    Funding bodies have their own requirements for suppliers to provide quality assured service, and structures to deliver savings for government.

    Looking back on over five years experience prescribing wheelchairs for people in remote Queensland communities, the following criteria are proposed as being of critical importance in determining whether a new wheelchair design will be viable as an everyday wheelchair in remote Australia.

1) Easily Funded.

    Many remote area wheelchair users are indigenous and rely on government funding schemes to pay the full cost of their wheelchair. Few people in remote Queensland communities contribute over the current $1200 subsidy. Some active users pay off installments or save a lump sum payment to obtain a higher quality wheelchair. Others find funding from different schemes or charitable sources though this is the exception, not the rule.

2) Suited to Multiple User Needs and Locations.

    Therapists often choose wheelchairs they know well, preferring a predictable outcome for several diagnoses. Common user diagnoses of full time wheelchair users include spinal injuries, hemiplegia (CVA, head injury), lower limb amputation and conditions associated with old age. Congenital disabilities such as Cerebral Palsy or Spina Bifida are not uncommon.

Wheelchair users in remote Australia have consistently needed provision for:

    a) Size should fit the user in terms of seat width and reach to push rings, seat depth, seat to footrest

    adjustment, back and arm heights.

    b) Posture support, skin and pressure care needs specific for the individual

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c) Efficient base for propulsion indoors and extreme outdoor areas, or at least safe push assisted

    transport in the chair outdoors

    d) Transfers in/out of the chair, lateral or standing

    e) Transport of the wheelchair by car, small plane and for some, restraint in public or private vans or

    minibuses

Meeting these criteria is particularly challenging given the variations in terrain and wheelchair user activity

    levels. Adapting regular wheelchairs with wider tyres provided only minor improvements in access to sand,

    steep and rough terrain. These “non standard items” can be difficult to fund as they are upgrades often

    considered “lifestyle choices”.

Radical increases in castors with 300mm diameter front wheels and a longer wheelbase on the Bushranger 4-

    wheeler (Figure 1) improved obstacle climbing and rough terrain access for a wheelchair user with hemiplegia

    and ataxia on hard ground, but made little difference on sand (Hales 2001).

Significant advances in sand access were achieved using beach wheelchairs with wide low-pressure tyres and

    a slightly tippy frame design. Some remote area wheelchair users have obtained funds for costly beach

    wheelchairs but some of those chairs have ended up seeing very limited use. One user tipped over backwards

    after waves lifted the buoyant front wheels, abandoning the chair from then on. Another living on a sand island

    found it difficult to transfer to the beach wheelchair once outside the home, persisting with their everyday

    wheelchair for most mobility around the soft sand community.

Two isolated wheelchair users in Queensland used the 3-wheeled Bushranger (Figure 2) as their everyday

    wheelchair. The long frame was not suited to tight indoor spaces, but the 3-wheel design was stable on

    uneven terrain, and extended wheelbase useful for steep forward tip angles.

Very active users have consistently stayed with compact designs for everyday use, opting for wide BMX tyres

    on the rear wheels. Most choose less adaptation of front castors, using 100-150mm diameter castors and

    negotiating soft or very rough ground mostly on the rear wheels, the front wheels acting more as stabilizers

    when coming to ground between push strokes.

While one wheelchair design cannot suit all users and locations, there must sufficient demand in the market for

    a product to be manufactured or imported in an ongoing manner, and ultimately become viable for remote

    wheelchair users.

3) Available, Reliable and Appropriate Technology.

Products must be available for trial before a firm order can be made. To be stocked by a regional supplier the

    product must be supplied by government, or have significant appeal for private purchasers in the area.

To be considered reliable and safe, funding bodies expect wheelchairs to have passed Australian Standards

    strength and stability tests, or to have passed International or European Standards with documentation

    checked by an engineer for approval.

Some funding bodies have extra requirements relating to reliability. In Queensland contracted suppliers must

    be Quality Assured and wheelchairs are expected to last a minimum lifespan, currently five years.

    Prescribers are asked to check that the user or carer can undertake the daily care and maintenance of the

    wheelchair. A maintenance checklist is issued with each new chair.

While regular cleaning, lubrication and tightening of loose parts can increase wheelchair lifespan; many never

    get around to these maintenance activities. There is wide variation in the build quality of wheelchairs on the

    funding bodies contract and each user has a different impact on the wheelchair. Some users are very active

    outdoors. Others are heavier or exert stronger forces due to ataxia or spasm. With such variation in users and

    products, lifespan has been found to be variable from 1-10 years. Repairs may be required within a number of

    weeks, or not for several years. To last the expected lifespan then, there must be a local or regional source

    of parts, service and repairs, such as Cairns for example to servicing Cape York and the Torres Strait. That

    supplier/repairer orders parts that are often specific to the make of wheelchair from the manufacturer / agent /

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distributor, usually in a capital city. Parts need be stocked or delays of six weeks or more are not uncommon

    waiting for items to be made or ordered in from overseas.

But wheelchair users could have more reliable mobility and repair costs reduced if common faults were

    eliminated by more appropriate technology design (National Forum of Independent Living Centres 1994,

    Hales & Sloane 2001). Common faults include:

    ? Early failure of moving parts such as spoked wheels, bearings (wheel and castor fork bolt bearings) and

    wheel locks

    ? Premature rusting of steel rims, brakes and fasteners, needing replacement long before the stainless steel

    or alloy frames

    ? Stretched or torn upholstery, cushions and footrests getting lost in transit compromising skin care and

    posture support

    ? Lack of adjustment for growth

    Figure 1 Bushranger 4 wheeler

    Figure 2: Bushranger 3 wheeler

Method.

This paper reviews trials of the prototype WorldMade 3 wheel rural wheelchair by UK development

    organisation Motivation. To assess the effectiveness of this design in meeting the criteria for an everyday

    wheelchair, the prototype was trialled with eight very different wheelchair users, seven indigenous and one

    non-indigenous, each in geographically diverse locations, as shown in Table 1 below. Locations are not

    named to provide at least a base level of anonymity.

It was also identified as important to demonstrate the design and obtain feedback in relation to the criteria from

    potential prescribers, private purchasers and those involved in approving funding or modifications. Therapists

    in remote areas; those working with outreach services or in regional cities prescribing for people returning to

    remote communities, were identified as potential prescribers. Home and Community Care (HACC)

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    Coordinators using wheelchairs for outdoor access were identified as potential purchasers. Local Area Coordinators often involved in finding one-off funding for individuals were identified as also having potential interest in the product. Engineers involved in Standards certification and approving product modifications, and advisors approving wheelchair funding were consulted. Sessions held with representatives of each of these groups are outlined in Table 2.

WorldMade (WM) 3 wheel rural wheelchair design and assembly set up for user.

    The WM wheelchair was designed for both active, confident wheelchair users with spinal injuries preferring a tippy rear wheel balance position; as well as amputees or others needing a very stable set up (Figure 3). Balance position is changed by moving the seat forwards / backward along the T-frame chassis and re-attaching clamps.

The marine ply timber seat is mounted to a T-frame chassis with 26” rear wheels mounting to cambar blocks

    on each side of the T, providing four degrees cambar.

    The seat is individually assembled to size for the user. Two alloy side panels are fixed to the seat and the backrest support brackets, from which the folding backrest is mounted. A contoured shell supports the skinned foam back pad, which has a pronounced lumbar curve. The shell can be set at tall and low settings.

    Push handles are angled out away from the apex of the back shell to provide a neutral upper limb position for an assistant to push, yet narrow enough not to interfere with scapula movement when pushing from the top of the push rings.

    The dual density foam cushion is thicker at the rear. A distinct ischial well and pommel raise are provided to encourage slight abduction of the thighs and weight bearing through the upper thighs and hips. A black fabric cover can be adjusted after cutting the cushion to length and width to fit the user.

    A marine ply footrest has an aluminium base plate and non-skid vinyl top layer. Velcro straps help support to both sides of the footrest and allow height adjustability of the calf strap. The footrest is angle and height adjustable with a rounded plastic sleeve and neoprene liner supplied to conceal a adjustment hardware and protect the user’s skin.

    Two marine ply arm supports with rounded top are designed to support the elbows and provide mechanical advantage for pressure lifts.

    “Off the shelf” alloy brakes are mounted under the seat. When pushed to lock position brake handles are well below cushion level to allow lateral transfers.

    A 220x60mm front castor wheel is set in a welded alloy fork from the end of the T-frame. The solid rubber castor tyre had been turned down to provide a narrow running surface at the centre on harder ground. Rear wheels were fitted with 26 x 1.95” BMX bike tyres with a knobbie tread.

    The WM chair was tried in the tippy balance position for all wheelchair users who participated in the study. Attempts were made to trial with above knee amputees but this was not successful within the time frame of the study, though may occur in future.

    Different tyre and wheel combinations were tried to enhance sand and water access. These were sourced and fitted in Australia after import. Early in the study a 12” diameter x 8” wide Roleez low pressure beach wheel was fitted for soft sand trials. The 26 x1.95” standard rear wheels were replaced mid-way through the study

    with a relatively smooth tread, downhill racer mountain bike tyre, 26 x 2.5” size, on 38mm heavy duty alloy rims. Table 1 lists the wheel configurations tried with each user.

    Trials involving both soft sand access plus full submersion were conducted late in the study by the author. The first involved two foamed urethane golf buggy wheels, 275 x 85mm, set together on one axle to provide a wide running surface on sand and non-pneumatic wheel kit less likely to float when submersed. The second trial involved the Roleez wheel half filled with water, the remaining volume of the tyre filled re-inflated with air.

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Table 1: Summary of wheelchair user trials.

    Age, gender & Location & Wheel Configuration Criteria assessed diagnosis Environments

    44yo male Regional city, paved Standard wheel kit Assessed posture support, T4 complete spinal areas outdoor and maneuverability and dynamics injury indoors of wheelchair

    30yo male Indoors and outdoors at Standard wheel kit 2 day trial to assess mobility T6 complete spinal remote outstation in indoors, on rough outdoor injury monsoonal savannah terrain, lateral transfers to/from

     country, plus further trial 4WD vehicle. Discussed

    indoors and outdoors at feasibility for everyday

    house in small isolated wheelchair, fold and transport,

    town seating and pressure care,

     maintenance.

    59yo male Remote island std rear wheels w Roleez 2hr trial at assessed feasibility Neuropathy, community, beach and beach wheel as the user’s primary everyday immobility road areas wheelchair, used mostly for

     longer distance mobility around

     community, beach fishing and

    hunting with family out bush.

    59yo female Remote mainland 26x2.5” rear tyres + 2hr trial comparing WM chair to T12 complete community, beach and Roleez beach wheel 4-wheel beach wheelchair, for spinal injury road areas soft sand access. To determine

     which was most suitabile for

    beach and local area camping

    access

    61yo male, lower Island off North std rear wheels and 1hr trial to compare to beach thoracic Queensland coastline, Roleez beach wheel wheelchair for sand and spondylotithesis outdoors on roads, shallow water access

    beach and shallow water

    46yo male Seaside community in Std rear wheels + 26 x Trial to assess beach and water L4/5 complete remote mainland 2.5” wide tyres, both w access for boat transfer spinal injury location, beach and boat Roleez beach wheel

    ramp access

    69yo male Wet tropics coastal Std wheel kit and with To assess if feasible for limited chronic illness, community, indoors at Roleez beach wheel indoor use and for outings with weakness home and access to local HACC service

    sandy creek bank

    26yo male, Outside home set in Std wheel kit To determine suitability of Cerebral Palsy bushland, wet tropics seating and backrest for mildly (mildly involved coastal community involved seating needs spastic

    quadriplegia)

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Table 2: Summary of sessions held with potential prescribers, purchasers and others with a key

    interest in the product.

Original product presentation by WorldMade Designer Ray Mines to Rehabilitation Engineers, Medical

    Aids Subsidy Scheme (MASS) Mobility Aids Advisor and MASS Engineer, Spinal Outreach Team

    Physiotherapists at Rehabilitation Engineering Centre, Brisbane

The product was demonstrated on eight further occasions with opportunity for feedback to:

    ? Occupational Therapists North West Queensland Allied Health Service Mt Isa, Thursday Island

    Hospital + Townsville Hospital

    ? MASS Mobility Aids Advisor Townsville ? MASS Mobility Aids Advisor + 1 Physiotherapist Cairns

    ? HACC Coordinators in Bamaga, Wujal Wujal ? Meeting of remote area Local Area Coordinators, Disability Services Queensland, Mareeba

Results And Discussion.

Nearly all of the criteria could be assessed over the various user trials, sessions with prescibers and author

    trials.

1) Easily Funded

    This criteria was not able to be assessed fully as the product is still at pre-production stage. Motivation aim for

    the production costs to remain very low, using mass production in a single size / one colour / standard parts

    format, transported by container, unassembled to a regional location. The goal is for costs to not exceed

    US$100 per wheelchair, delivered to regional point of distribution.

Transport within Australia, product trial, prescription and assembly for the individual user, plus any adaptations

    such as different wheels would occur at the regional centres’ expense. Costs incurred within Australian can be

    substantial; $350+ to build wider rear wheels, $250+ to make a fork and fit a low pressure beach wheel at

    front, etc. It is unlikely that the final price would exceed the $1200 subsidy in Queensland, but there may be

    challenges from funding bodies, insisting users self fund wider wheels for the “lifestyle preference” of beach or

    bush use.

All three Mobility Aids Advisors consulted felt they could approve the wheelchair for individual users living in

    very remote areas, though they would need to be very confident that the user would not want a standard 4-

    wheel wheelchair from the MASS scheme as well as the WM chair, as only one wheelchair can be supplied.

Local Area Coordinators and HACC Coordinators felt they could fundraise or apply for one-off funds for the

    chair. It the price was less than $300-$500 it was seen as extremely easy to purchase without special

    approvals.

2) Suited to Multiple Users and Locations

A variety of diagnostic groups were represented, each with different outcomes in relation t user and location

    criteria, as described below.

a) Size: The prototype had a seat width of 40cm, a seat depth of 46cm, though actual seat depth was 43cm

    in front of the backrest pad.

    Seat width was adequate for all eight users who tried the chair turning push rings through a ? turn arc.

    Seat depth was adequate for all except one tall user who would ideally have had a 48cm seat depth.

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    The high back position and pre-contoured backrest pad were not tried again after the first wheelchair user, with T4 complete spinal injury could not maintain his posture against the backrest when at rest. This was consistent with overseas feedback that the back was too upright, reported to the author prior to initial delivery of the WM wheelchair in Australia. A more reclined back pad was made from foam scraps and substituted for the original. The tall back height was not used again throughout the trials except with the user with cerebral palsy. All other users achieved sufficient stability from the lower back height, though the taller user (mentioned above in relation to seat depth) would have had more comfort at the tall setting.

    Seat to footrest was not long enough for the two taller users over 180cm tall, but had already been shortened on the prototype prior to its arrival in Australia. The pre-shortened size would likely suit all users up to 185cm or possibly a little taller.

    None of the wheelchair users were able to keep their whole foot flat on the footrest, most sitting with toes and metatarsal heads touching, heels in the air. A more neutral angle was supposed to be achievable by swapping mount brackets around but was not significant enough to obtain full foot support. This was complicated by the footrest being so far back to allow for the front wheel, and the long seat depth. Users ended up sitting at around 90-100+ degrees knee flexion, so the footrest needed to be zero degrees, level with the floor.

    b) Posture support, skin and pressure care needs were well designed for the sample of eight wheelchair

    users. The user with Cerebral Palsy achieved some correction of his non-fixed kypho-scoliosis against the reclined back pad. He was also able to maintain legs in the midline on the WM cushion and solid seat his

    legs were windswept on his slung seat, folding wheelchair. Seat angle varied from 7.5 to 10 degrees on the solid seat board, 2.5 to 5 degrees at cushion surface. Taking into account compression of the seat and back cushions when seated, all users probably ended up close to 95 degrees seat to back angle against the reclined back pad

    All users maintained their pelvis toward the rear of the cushion for the duration of the trials. While encouraging this result is not conclusive as the focus for many trials was on mobility, rather than posture over the course of the day. Longer trials over weeks or months would be required to ensure there was no tendency towards sacral sitting.

    The ischial well is narrow enabling narrower hip width adults to support the greater trochanters. With the footrest lowered to promote thigh load (Figure 4), peak pressures around the ischial tuberosities were reduced, as confirmed by pressure mapping study with the user with T6 complete spinal injury. At 10yrs post injury he was quite thin over the buttocks but had put on a lot of abdominal and upper body weight. Figure 5 shows the 3-dimensional Xsensor map for this user; the pressure peak on the left linked to clothing bunched around his left greater trochanter. Pressures around the ischial tuberosities (ITs) ranged from 60-129mmHg with an average of 106mmHg, comparing favourably with much more expensive pressure reduction cushions made in the West.

    The cushion cover is somewhat multi-stretch and has minimum moisture resistance, possibly sufficient for small spills but was not able to hold back any volume of fluid, as occurred in one of the trials.

    The two T-nuts positioned at the rear middle section of the seat, are a potential threat to skin care if the user ends up sitting without their cushion for any period of time. These secure the backrest locking strip to the seat and have potential to be altered if a different locking system or fastening was used.

    c) Efficient base for propulsion indoors and extreme outdoor areas

    As described in a) above, users were able to achieve easy reach to push rings. If the seat had been narrower she may have achieved better reach, but for women there is often a compromise between allowing sufficient hip width and shoulder to push rim relationship.

    Both men with spinal injuries in the remote areas felt the 26” wheels helped provide a powerful push stroke. The user with T6 injury was very efficient getting around inside his home, with no collisions with walls or furniture.

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    On soft sand with 26x2.5” tyres, the user with L4/5 spinal injury could not push for more than a few push strokes at a time, the wheels bogging up just under rim level. He stated that he would have persisted with these wheels when he was younger, but at this time his shoulders were not up to the task. Recent innovations by Colors USA with their massive Fatso rear wheels (Figure 6) provide inspiration for more successful floatation of the drive wheels on soft sand. If such a wheel could be sourced or made in Australia, it could be used on the WorldMade wheelchair. Equally likely though is for active users to swap them for their conventional wheels on arrival at the beach, fitting to a conventional frame.

    Both remote area spinal injured men were asked if the chair would suit use as an everyday wheelchair. The user with L4/5 injury preferred to think of the WM chair for beach and boat access, while the user with T6 injury was very keen to use the chair full time. Both felt the chair was tippy enough while the user with T4 spinal injury in the city felt it should be more tippy. The woman with T12 spinal injury and man with CP felt the chair was too tippy at the tippy position, but neither seemed appropriate for the stable setting, as that would likely have discouraged them using what active skills they had.

    Several people commented that the design of the push handles and tippy set up made the chair very easy to push. When the chair was pushed from behind onto soft sand with the 220x60mm front castor, it immediately bogged in up to castor axle level; the footrest bottomed out and stopped the chair moving further forward. With the standard wheels and castor then, the chair would need to be pulled backwards over soft sand, or used by very active users wheel standing along with each push stroke. When the chair was pushed with the Roleez sand wheel, it barely made an impression on the sand while the rear wheels bogged in slightly (Figure 7). The carer for the woman with T12 spinal injury felt the WM wheelchair was as easy to push over soft sand as a four wheel beach wheelchair, and easier to control direction than the beach design. The seated user however felt insecure when left unattended with rear wheels slightly bogged into the sand, feeling like the chair could tip over backwards too easily (Figure 8).

    Further assessment of extreme outdoor access was undertaken in relation to steep forward tip angles and submersion. Users could not cope with anything steeper forward angles than 1in 4. For slopes of 1 in 3 or greater the chair must be tipped onto rear wheels to descend.

    The success on soft sand was followed by some difficulties out in the water for two users, one who wanted to join his family when fishing, the other wanting to transfer to a boat. The Roleez beach wheel became very buoyant once 30 to 35cm under water and users without very dynamic sitting balance would have been quickly tipped over backwards. Even slight waves brought on by a gentle breeze triggered this tipping action. Both users needed to get out a bit deeper, between 40 to 60cm deep to achieve their respective goals.

    Submersion trials conducted by the author later in the study were also unsuccessful. The pair of golf buggy wheels floated uncontrollably once 40cm deep. When the Roleez beach wheel was half full of water it became incredibly difficult to transport the chair, the front end dropping uncontrollably when trying to lift out of the car. Despite the extra 2-3kg weight up front, the chair still floated once 35cm deep (Figure 9). Further trials will be required to resist floatation. The original 220x60mm castor wheel was not tried underwater and is unlikely to float. But given the immediate bogging experienced with this castor wheel on the beach, it would likely be seen as a less than ideal solution by many users.

    d) Transfers: Most of the therapists and engineers immediate reaction was to declare the chair unsuitable

    for users doing standing transfers. Only two therapists put forward the view that alert wheelchair users could work around the fixed footrest and central beam.

    Users doing lateral transfers hesitated, unsure of what to hold onto to move across onto the seat. Each eventually made the transfer then had to re-position legs over the central beam afterwards, adding an unfamiliar part to the transfer routine. There was one exception, a 73yo above knee amputee who tried to transfer to the chair with two people assisting. She was caught up on the metal side guards which project 8cm in front of the wheels when the seat is brought forward on the chassis to the stable balance position. She was unable to transfer and trial the chair unfortunately.

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    Several users and therapists stated they would like to have something more to get a grip on while

    transferring. The timber side panels while useful for pressure lifts, were not of use for standing or lateral

    transfers.

e) Transport

    Two of the eight wheelchair users felt that transporting the wheelchair was not a problem. Some of the

    other wheelchair users were uncertain about transport, and one felt the front end needed to fold or detach

    from just in front of the footrest. Several service providers also felt the frame was too long for easy

    transport.

    With rear wheels removed and backrest folded forward, the chair was approximately 120cm long by 60cm

    wide by 70cm tall. After numerous car, taxi and aircraft trips made over the course of the trials, the

    wheelchair was found to:

    ? fit in the boot of large six cylinder sedan vehicles with back folded and wheels removed

    ? fit in four wheel drive stationwagons with back folded and wheels still attached

    ? fit Metro, Islander and Twin Otter aircraft which fly to approximately half of Queensland’s most remote

    communities

    ? not fit in any plane of 7 seats or less, except Islanders which are used for only a minority of the shorter

    flights in the Torres Strait

    ? secure easily to wheelchair restraint assemblies, hooks anchoring around the front seat support and

    rear seat support brackets (Figure 10)

3) Available, Reliable and Appropriate Technology

    As a prototype the chair is not in production and there appear to be numerous hurdles to making it available to people in remote Australia. The chair was of interest to all eight wheelchair users but only two would have

    liked it as an everyday chair to the extent they would forego funding of a conventional wheelchair. Even then, there was some uncertainty about one of these wheelchair users future living situation, so few prescribers

    would risk applying for a bulky 3 wheeler when he could end up living in the city for periods of time. Three

    others had a strong interest in the product as a second chair for regular use, several times a month. The

    remaining three wheelchair users were uncertain, possibly using the chair occasionally on outings, with one

    user insisting the chair must not float for him to use it.

Demand for the chair from remote area wheelchair users may well be a trickle. If the product had wider appeal

    as a second wheelchair for users in metropolitan areas then demand may grow to more encouraging levels for

    potential suppliers.

Plans for distributing the product involve selling by the container, 300 at a time in order to achieve the

    economical pricing hope for. It is difficult to see how one state or territory, or single importer could justify such a large order in the beginning for an outlay of US$30 000.

Significant interest was expressed by a wheelchair user in North Queensland who is also a supplier, but the

    need for Quality Assurance and high overheads were serious disincentives for that individual to become an

    importer. He could certainly be relied upon as a point of assembly and for sourcing parts and repairs as he has been the primary repairer for the region for many years.

The criteria of reliability ensured by Standards Testing and that of 5-year lifespan could not be assessed as

    the product is still to be tested to European Standards.

How well the product met the appropriate technology design challenge was assessed. The solid seat and

    backrest supports provide a low maintenance system and while foam cushioning will perish in less than five

    years with daily use, alternatives can be used, the original copied locally, or genuine replacements may be

    able to be sourced.

Potential sources of corrosion have been reduced. The chassis, brackets and clamps, backrest shell, side

    panels and push handles are aluminium. All parts are joined using the same diameter stainless steel allen

    bolts in various lengths, locked by 13mm nuts or T-nuts. All of this joining and assembly hardware is stainless

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    steel. Not only is this maintenance free, but very simple having to use a single open ended spanner and allen key to do all adjustments.

Very hard Vesconite bushes are used instead of steel roller bearings to run front and rear wheels, and for

    rotation of the castor pintle or fork bolt. Their performance was noted to exceed that of nylon bushes at free spinning providing some confidence they will last longer than nylon too.

    Axles and wheel nuts, axle sleeves and the pintle or fork bolt itself are all steel, and the backrest locking strip is spring steel. Surface rust appeared on all of these within six months, needing wire brushing and lubrication to restore.

    Marine ply used for the seat, footrest and arm supports is waterproof, and can be replaced or substituted in most localities without the repairer feeling outside their skill level. It was noted that the arm supports could easily get lost. To make new arm supports requires steam bending of plywood to achieve a quarter turn at the top, not be easily replicated in a remote location, though many local people could improvise an alternative. The footrest is very robust and by virtue of its position between front and rear wheels this is a safe design choice.

    The castor barrel block inserted into the end of the T-frame conceals the top of the castor fork bolt, helping prevent corrosion or clogging from substances entering the top of the assembly. To change or maintain the castor fork and fork bolt requires a rolled steel pin to be punched out, best attempted by someone with mechanical experience.

The “off-the-shelf” brakes are of some concern as they have plastic bushes, known to last as little as 18

    months before loosening so much they shift mid-transfer, especially for people with higher spinal injuries.

Conclsions.

    The prototype WorldMade 3 wheel rural wheelchair attracted considerable interest from wheelchair users, presribers, potential buyers, engineers and funding bodies. But there are serious doubts as to whether the product could attract sufficient orders to come by bulk shipment of 300 wheelchairs, and therefore achieve the low pricing goals. If smaller numbers are imported the price will rise which could stifle demand.

    Ultimately the product needs to have high demand to succeed. This could be achieved by ensuring those whose criteria were only partly met in this study, have their needs fully met by modifying the design. The inability to transport the chair in small aircraft is a critical shortcoming which would have to be overcome. Given the feedback relating to standing transfers and potential falls around the footrest, a folding footrest should be considered. A balance setting between tippy and stable would allow adjustment to suit all users, rather than a focus on active and passive. If the product can roll out a standard width door, across the soft sand, and withstand occasional submersion without steel parts rusting, and resist floatation, it may well end up going where other products fear to tread.

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