SIMPLE WHEELCHAIRS & OTHER VEHICLES

INTRODUCTION

Wheelchairs which are cheap, strong and can be locally manufactured, are required by the thousands by many economically poor countries of the world to-day. In these countries there are millions of crawling patients, not only with severe poliomyelitis but also with paraplegia and quadriplegia due to spinal tuberculosis, injuries and transverse myelitis. There are also numerous patients with severely deformed or amputated limbs due to trauma, untreated congenital deformities, severe osteomyelitis, pyogenic and tuberculous arthritis and leprosy. The necessity for a wheelchair may be urgent, as the penalty for lack of mobility in developing countries is usually an early death through neglect and starvation.

It will be many years before adequate surgical treatment will be available for most of these patients, and even with simple calipers and simple operations to correct deformities, there will still be many thousands of patients who, through the severity of their deformities or paralysis, or the weakness of their arms, will require wheelchairs for the rest of their lives.

Wheelchairs as manufactured in Europe and North America cost several hundred dollars, and sometimes much usual more by the time they reach most developing countries. They have the advantage of lightness and of being collapsible. They have the very marked disadvantage, apart from cost, of being unable to stand up to rough roads and of being difficult to repair locally. A very simple wheelchair is, therefore, necessary and has been designed by the author in an effort to find a solution to this problem.

In an effort to design a suitable chair, the first prototypes were made out of old broken metal frame chairs which were rewelded, with a supporting frame for the wheels added. Canvas seats and backs were made out. of old canvas mail bags, bogie wheels were obtained from old hospital trolleys and wooden chocks were used for brakes. More sophisticated versions of this chair were developed from this initial prototype. The design considerations involved will first be discussed before the technical details of construction are described, as these may have a bearing on modifications of the chair for different countries, and in different conditions.

DESIGN CONSIDERATIONS FOR WHEELCHAIRS IN DEVELOPING COUNTRIES

The design of a suitable wheelchair for developing countries presents several problems. It must be simple enough to be manufactured locally out of easily available materials with semi-skilled labour, cheap enough to be a practical proposition and strong enough to stand up to rough roads, mud, dust and water.

The wheelchairs which will be described fulfill these criteria. They can be manufactured in any simple metal workshop, and all the materials required for their construction axe usually readily available in economically poor countries. The retail cost of materials is relatively cheap US $50-100, and this could be reduced considerably if materials were bought wholesale, or if old frame chairs were available at minimal cost.

Eight prototypes of different types were extensively tested over several months before the present designs were settled upon (Fig. 31(q) - (v)). Over 1,000 have been made to date, and hard usage for over seven years has not produced any wear except in that easily replaceable spindles and ball bearings of the main wheels and the cheaper types of bogie wheel. This is in contradistinction to the imported wheelchairs which all needed extensive repairs after much less use.

Patient-propelled wheelchairs, in addition, should be a compromise of being low enough for patients with weak arms to climb in and out of easily, and yet high enough to clear potholes and small drains without outside help. They should not be too wide, as this decreases their usefulness on paths, increases the difficulties of propulsion, and makes it difficult to get through the usual narrow doors of houses. The width of the wheelchairs described depends on the frame chair used, but it is a little wider than a conventional wheelchair due to the necessity of supporting both ends of the axles of the main wheels. The advantages of using cheap and universally available bicycle wheels in manufacture, however, far outweigh disadvantages of width. If necessary, the chair can be narrowed by removing segments of the transverse struts and re-welding them.

The ability to be collapsible is of secondary importance to strength and cheapness of construction. This is especially so in countries where private cars are the exception rather than the rule, and where buses and taxis, when available, have roof racks which can take wheelchairs and bicycles without difficulty.

The size of the main propulsion wheels is 28, the usual size available in developing countries, and therefore cheap and easily repairable. In countries where the standard bicycle wheels are of a different size, this size, of course, should be used. The large wheels afford good tractive power for a patient with weak arms, and are far better over rough ground than small wheels in an unsprung chassis. The centre of gravity of the patient should be just behind the axis of the wheels to obtain maximum tractive effect on the main wheels. This will also enable a patient to tilt the chair forward by sliding forward in the chair to get the bogie wheel out of a drain or pothole, as well as facilitating getting in and out of the chair. A single trailing bogie wheel will allow both main driving wheels to be always on the ground, especially in uneven country. This is not so with two wheels.

The bicycle wheel tyres were originally used instead of propulsion rails for propelling the chair forward, as they were cheaper, and many patients prefer to use the tyres themselves when clean. A propulsion rail, however, can also be attached without the necessity of widening the external frame. The extra cost of materials is approximately and can be easily attached. (Fig. 31(v)).

Bogie wheels were experimented with, taking into consideration both size and position; 4,5, 6 and 8 sizes were tried with single or double wheels either in the front or the back. Front bogie wheels, whether single or double, were discarded in patient-propelled wheelchairs for rough road use, as they were easily obstructed by potholes and gullies. A single trailing wheel not only becomes obstructed less, but can also be tilted out of a pothole. It also acts as a prop to prevent the wheelchair tilting backwards when going up hills.

The size of the bogie wheel depends on availability and cost. The larger wheels are heavier, more expensive and more difficult to obtain. They are, however, better on rough ground; 5 or 6 wheels are probably the best compromise, but 4 wheels are cheaper and have proved fairly satisfactory where patients do not have to go over rough surfaces. Bogie wheels have been found on the whole to be hard-wearing, but poor quality ones may wear at the spindle. It has been found advisable, therefore, to bolt rather than to weld the bogie wheel on to the back plate in order to facilitate renewal of worn wheels.

The use of old chairs as the main frame has the advantage that the basic chair is available without the necessity of a jig. Once mass-production starts, however, the manufacture of the entire chair should be embarked upon from scratch, and modifications introduced if necessary. The use of three-quarter inch conduit tubing can make the chair easier to manufacture, but heavier; three-quarter inch furniture tubing is lighter and stronger, but will require a tube-bending machine.

Various other chairs were experimented with and three types of wheelchair will be described. Attempts were also made to use wooden frame chairs. These proved easier to fit with bicycle wheels, but using a supporting frame of 1.5 x 0.25(38 mm x 64 mm) flat steel instead of tubing screwed to the chair. Although this proved fairly satisfactory for gentle indoor use, these chairs did not stand up to hard usage or outdoor conditions, and were heavier and more cumbersome.

The important point in the design and mass-production of wheelchairs for economically poor countries, as with other appliances is the necessity of keeping the design simple and cheap. Overenthusiastic workshop supervisors should not be allowed to make too many complicated additions at the expense of quantity and strength. The production line should concentrate on the simplest satisfactory design, and modifications should be added as required. These include foot-boards, specially built up foot rests, arm rests and extra narrow or high seats with a head rest, if necessary. A scaled down wheelchair can be made for children.

In the case of paraplegic patients 3 foam plastic or other padding is essential for the seat, and this should be covered by waterproof material to keep it in place. If cost allows, however, all wheelchairs should be padded with 3 foam plastic for the seats and 2 foam plastic for the backs. In the case of patients who cannot propel themselves, two bogie wheels at the front should be put in place of the back wheel (Fig. 31(v)),, and a strut added to prevent the chair tilting backwards. The external frame should be welded so that the axis of the wheels is now level with the back of the seat and the centre of gravity of the chair, therefore, in front of this. The top of the type I chair, however, is ideal for pushing and does not require modification in any way. A piece of 0.75 (19mm.) tubing for pushing is present on the type III chair.

Another modification of the standard wheelchair is a double tubing extension forward in the place of bogie wheels in order to turn the wheelchair into a vehicle suitable for being towed by a bicycle. Numerous modifications and types of this pedicab are naturally possible on the various types of chair available. A frame of 0.25 (6.4mm) or 0.375 (8 mm) mild steel rod can also be easily attached to a chair, and to this is added a detachable canvas awning with a front and back transparent panel. This totally encloses the chair and makes it weatherproof in the rainy season. It should be possible to detach the whole frame completely as well., and the canvas panels on the front, sides and back should be made so that they can be rolled up to the roof and fastened there when not temporarily required. The technical details of manufacture of simple type I and III wheelchairs are illustrated in Figs. 31(q) - (y).

TYPE I WHEELCHAIR — MATERIALS

a. Basic chair — 0.75(1.9cm) outside diameter furniture tubing - 22 feet(693cm).

b. External frame — 0.75 furniture tubing 14 feet(427cm).

c. Brake — 0.25 (0.6cm) steel rod, 3.5 feet (107cm).

d. Handle — 1 x 0.125(2.5cm x 0.3cm) steel flat 12(30.5cm) .

e. Gate — 3/4 x 0.125(1-9 x 0.3cm) steel flat, 1 foot (30.5 cm).

f. Wheel supports — 1.5 x 0.25(3.8 x 0.6 cm), 1 foot steel flat.

g. Castor supports

Angle — 1 x 0.25(2-5 x 0.3cm) steel angle, 3 feet (91.4cm).

Plate — 4 x 0.25(10.2 x 0.6cm) steel flat 6 feet(15.2cm).

h. Main wheels x 2 — 28(122cm) complete with tyre, tube & valve.

i. Bogie wheel — 5 castor(12.7cm) or 4 or 6.

j. Seat and back — 3/8 plywood 6.25 square feet.

k. Paint

White undercoat — 0.25 pint(148 ml).

White finishing coat — 0.25 pint.

Wood stain — 0.25 pint.

l. Miscellaneous

Bolts and nuts — 4.

Woodscrews No.10 — 1.25 - 8.

TYPE III WHEELCHAIR MATERIALS

a. Basic chair — 0.75(1.9cm) Outside diameter 14 feet(427cm) furniture tubing.

b. Seat frame — 0.75(305 cm). furniture tubing - 10 feet.

c. Support frame

0.75furniture tubing.

1(2.5 cm) furniture tubing — 1.75 feet(53.3 cm).

d. Castor supports — 0.25(0.64) — 25 square inches(161 square cm).

e. Main wheels x 2 — 28(71 cm) complete with tyre, tube & valve.

f. Bogie wheel — 5 castor(12.7cm) or 4 or 6.

g. Hand rim — 0.5(1.27 cm) furniture tubing — 13 feet(396 cm).

h Brake

O.75 furniture tubing — 10(25.4 cm).

0.185 x 0.75(0.48 x 1.9 cm) — 2 feet(61 cm).

0.5(1.27 cm) furniture tubing — 4(10 cm).

0.375(0.96 cm) steel rod — 2.33 feet(71 cm).

i Brake lock

0.185(0.48 x 1.9 cm) flat steel — 3(7.6 cm).

0.25 x 0.5(0.64 x 1.27 cm) rivets — 2.

j. Seat and back — 0.375(8mm) plywood 1.7 square feet(48 square cm).

k. Seat — 0.375 (8 mm) plywood 1.5 square feet(40square cm).

l. Foot support — 0.375 (8mm) plywood 0.75 square feet(20 square cm).

m. Padding

3(7.6 cm) foam for seat — 2.7 square feet (71.5 square cm)

2(5.1cm) foam for back — 2.7 square feet (71.5 square cm).

Artificial leather covering — 7.5 square feet (201 square cm).

n. Paint

Grey undercoat — 0.5 pint(296 ml).

White finishing coat — 0.5 pint.

Thinner — 1 pint.

o. Miscellaneous

Bolts and nuts — 0.375 x 0.75(0.8 x 1.9 cm) 4.

Woodscrews No.10 — 1.25 - 10.

Electrodes(No 12) 1.25 — 2

Welding rods — 10

Glue

THREE-WHEELED CHAIRS (Hand-propelled) - Figs. 31(w), (x), (y).

There are a variety of hand-propelled chairs on the market in economically rich countries, but these are not made to stand up to rough roads. Alternatively, a simple, rugged, cheap chair can be built from a simple locally produced wheelchair by welding a front bicycle wheel fork with a single 20 wheel in front, and two 28 bicycle rear wheels at the back. Propulsion is by bicycle pedals and chain direct on to the front wheel, and two ordinary bicycle brakes are used on the back wheels. The addition of a three-speed gear,front and back lights, a simple hood, a horn and a luggage carrier under the seat can all improve this. The three-wheel chair illustrated (Figs. 31(w), (x) and (y)) is one in which simple bicycle components have been adapted to an ordinary type III wheelchair. This three-wheel chair has proved itself on rough roads, and can be propelled for long distances much more easily, and much faster, than the ordinary wheelchairs with two main wheels. Numerous prototypes were tried out with a variety of propulsion mechanisms before the chair illustrated went into production. Despite this, further modifications in the future will probably help to stabilise the chair further and improve on its propulsion. A motorised version is also being designed.

MECHANICALLY PROPELLED CHAIRS

Most manufacturers of wheelchairs sell a variety of chairs, from electrically propelled wheelchairs to sophisticated three-wheel chairs with small two-stroke and even four-stroke engines. An ingenious handyman in a workshop in a developing country could easily adapt a locally produced three-wheel chair to propulsion by means of an old lawn mower or motor scooter engine.

CARS ADAPTED FOR DISABLED DRIVERS

Standard cars, adapted with controls for invalid drivers, are usually a much more practical proposition for the disabled who can afford them in developing countries than invalid cars themselves. They may initially cost more, but they stand up to rough roads much better than invalid cars designed for well surfaced roads, and they are much safer.

SUPPORTS FOR THE SEVERELY DISABLED

These are illustrated in Figs. 31(za) and (zb). Such supports may have a very real place for the severely disabled in economically poor countries.

BALKAN BEAMS (Figs. 31(zb) and (zc))

Simple orthopaedic beams which can be used to support limbs both postoperatively and during physiotherapy are illustrated. They are much cheaper and lighter than imported types of beam, and are easily made locally out of angle iron or furniture tubing as shown.