Wheelchair
A wheelchair is a mobilized form of chair using two or more wheels, a footrest, and an armrest usually cushioned. It is used when walking is difficult or impossible to do due to illnesses, injury, disabilities, or age-related health conditions. Wheelchairs provide mobility, postural support, and freedom to those who cannot walk or have difficulty walking, enabling them to move around, participate in everyday activities, and live life on their own terms.
Wheelchairs come in a wide variety of formats to meet the specific needs of their users. They may include specialized seating adaptions, and individualized controls, and may be specific to particular activities, as with sports wheelchairs and beach wheelchairs. The most widely recognized distinction is between motorized wheelchairs, where propulsion is provided by batteries and electric motors, and manual wheelchairs, where the propulsive force is provided either by the wheelchair user or occupant pushing the wheelchair by hand, by someone else pushing from the rear using the handle, or pushing from the side using a handle attachment.
History
The Sanskrit grammarian Pāṇini mentions the Sanskrit word parpafor wheelchair in his .Image:Recueil d'ouvrages curieux de mathematique et de mecanique; ou, Description du cabinet de monsieur Grollier de Serviere. Avec près de 100 planches en taille-douce .jpg|thumb|120px|alt=Nicolas Grollier de Servière wheelchair in his Cabinet of curiosities|Nicolas Grollier de Servière wheelchair in his Cabinet of curiosities
The earliest records of wheeled furniture are an inscription found on a stone slate in China and a child's bed depicted in a frieze on a Greek vase, both dating between the 6th and 5th century BC. The first records of wheeled seats being used for transporting disabled people date to three centuries later in China; the Chinese used early wheelbarrows to move people as well as heavy objects. A distinction between the two functions was not made for another several hundred years, until around AD 525, when images of wheeled chairs made specifically to carry people began to occur in Chinese art.
Although Europeans eventually developed a similar design, this method of transportation did not exist until 1595 when an unknown inventor from Spain built one for King Phillip II. Although it was an elaborate chair having both armrests and leg rests, the design still had shortcomings since it did not feature an efficient propulsion mechanism and thus required assistance to propel it. This makes the design more comparable to a modern-day highchair or portable throne for the wealthy than to a modern-day wheelchair for disabled people.
In 1655, Stephan Farffler, a 22-year-old paraplegic watchmaker, built the world's first self-propelling chair on a three-wheel chassis using a system of cranks and cogwheels. However, the device resembled a handcycle more than a wheelchair since the design included hand cranks mounted at the front wheel.
A self-propelled wheelchair was made for the Parliamentarian commander-in-chief Sir Thomas Fairfax due to the many injuries he had received during the English Civil War, and he used it during the final years of his life. The wheelchair of Thomas Fairfax is currently on display at the National Civil War Centre in Newark-on-Trent.
The invalid carriage or Bath chair brought the technology into more common use from around 1760.
In 1887, wheelchairs were introduced to Atlantic City so invalid tourists could rent them to enjoy the Boardwalk. Soon, many healthy tourists also rented the decorated "rolling chairs" and servants to push them as a show of decadence and treatment they could never experience at home.
Modern wheelchairs
In 1933 Harry C. Jennings Sr. and his disabled friend Herbert Everest, both mechanical engineers, invented the first lightweight, steel, folding, portable wheelchair. Everest had previously broken his back in a mining accident. Everest and Jennings saw the business potential of the invention and went on to become the first mass-market manufacturer of wheelchairs. Their "X-brace" design is still in common use, albeit with updated materials and other improvements. The X-brace idea came to Jennings from the men's folding "camp chairs/stools", rotated 90 degrees, used in the outdoors and at the mines.Types
There are a wide variety of types of wheelchairs, differing by propulsion method, mechanisms of control, and technology used. Some wheelchairs are designed for general everyday use, others for single activities, or to address specific access needs. Innovation within the wheelchair industry is relatively common, but many innovations ultimately fall by the wayside, either from over-specialization or from failing to come to market at an accessible price point. The iBOT is perhaps the best-known example of this in recent years.Manual self-propelled wheelchairs
A self-propelled manual wheelchair incorporates a frame, seat, one or two footplates, and four wheels: usually two caster wheels at the front and two large wheels at the back. There will generally also be a separate seat cushion. The larger rear wheels usually have push-rims of slightly smaller diameter projecting just beyond the tyre; these allow the user to manoeuvre the chair by pushing on them without requiring them to grasp the tyres. Manual wheelchairs generally have brakes that bear on the tyres of the rear wheels, however, these are solely a parking brakes and in-motion braking is provided by the user's palms bearing directly on the push-rims. As this causes friction and heat build-up, particularly on long downslopes, many wheelchair users will choose to wear padded wheelchair gloves. Manual wheelchairs often have two push handles at the upper rear of the frame to allow for manual propulsion by a second person; however, many active wheelchair users will remove these to prevent unwanted pushing from people who believe they are being helpful.Everyday manual wheelchairs come in two major varieties, folding or rigid. Folding chairs are generally low-end designs, whose predominant advantage is being able to fold, generally by bringing the two sides together. This is an advantage for people who need to store the wheelchair frequently or to put it in a small vehicle. Rigid wheelchairs have permanently welded joints and many fewer moving parts. This reduces the energy required to push the chair by eliminating many points where the chair would flex and absorb energy as it moves. Welded rather than folding joints also reduce the overall weight of the chair. Rigid chairs typically feature instant-release rear wheels and backrests that fold down flat, allowing the user to dismantle the chair quickly for storage in a car. A few wheelchairs attempt to combine the features of both designs by providing a fold-to-rigid mechanism in which the joints are mechanically locked when the wheelchair is in use.
Many rigid models are made with light materials such as aluminium and titanium, and wheelchairs of composite materials such as carbon-fibre have started to appear. Ultra lightweight rigid wheelchairs are commonly known as 'active user chairs' as they are ideally suited to independent use. Another innovation in rigid chair design is the installation of shock absorbers, such as "Frog Legs", which cushion the bumps over which the chair rolls. These shock absorbers may be added to the front wheels, to the rear wheels, or both. Rigid chairs also have the option for their rear wheels to have a camber, or tilt, which angles the tops of the wheels in toward the chair. This allows for more mechanically efficient propulsion by the user and also makes it easier to hold a straight line while moving across a slope. Sport wheelchairs often have large camber angles to improve stability.
Rigid-framed chairs are generally made to measure, to suit both the specific size of the user and their needs and preferences around areas such as the "tippyness" of the chair – determined by the distance between the center of gravity and the rear axle. Experienced users with sufficient upper-body strength can generally balance the chair on its rear wheels, a "wheelie", and the "tippyness" of the chair controls the ease with which this can be initiated. The wheelie allows a wheelchair user to climb and descend curbs and move more easily over small obstacles and irregular ground such as cobbles.
The rear wheels of self-propelled wheelchairs typically range from in diameter, and commonly resemble bicycle wheels. Wheels are rubber-tired and may be solid, pneumatic or gel-filled. The wheels of folding chairs may be permanently attached, but those for rigid chairs are commonly fitted with quick-release axles activated by depressing a button at the centre of the wheel.
All major varieties of wheelchairs can be highly customized for the user's needs. Such customization may encompass the seat dimensions, height, seat angle, footplates, leg rests, front caster outriggers, adjustable backrests and controls. Various optional accessories are available, such as anti-tip bars or wheels, safety belts, adjustable backrests, tilt and/or recline features, extra support for limbs or head and neck, holders for crutches, walkers or oxygen tanks, drink holders, and mud and wheel-guards as clothing protectors.
Light weight and high costs are related to the manual wheelchair market. At the low-cost end, heavy, folding steel chairs with sling seats and little adaptability dominate. Users may be temporarily disabled, or using such a chair as a loaner, or simply unable to afford better. These chairs are common as "loaners" at large facilities such as airports, amusement parks and shopping centers. A slightly higher price band sees the same folding design produced in aluminium. The high end of the market contains ultra-light models, extensive seating options and accessories, all-terrain features, and so forth. The most expensive manual chairs may rival the cost of a small car.