Wheel chairs have been used since the late seventeenth century to assist people to manoeuvre themselves. Over the years many different kinds of wheelchairs have been invented to suit people with different needs.
Conventionally modern wheelchairs are either self propelled or driven by motors with different adaptations available. The following is a brief overview of what is available today.
Manual or self-propelled wheelchairs are propelled by the occupant, usually by using large rear wheels, from 20-26 inches in average diameter, and resembling those of bicycle wheels. The user moves the chair by pushing on the handrims, which are circular tubing on the outside of the large wheels. Skilled users can control speed and turning and often learn to balance the chair on its rear wheels - do a "wheelie". The wheelie is not just for show - a rider that can control the chair in this manner can climb and descend curbs and move over small obstacles.
Attendant-propelled chairs are designed to be propelled by an attendant using the handles, and thus the back wheels are rimless and often smaller. These chairs are often used as 'transfer chairs' to move a patient when a better alternative is unavailable. Special airplane transfer chairs are available on most airlines, designed to fit narrow airplane aisles and transfer a wheelchair-using passenger to and from their seat on the plane.
Powerchairs may be designed specifically for indoor use, outdoor use, or both. Powerchairs are generally prescribed for persons who have difficulty using a manual chair due to arm, hand, shoulder or more general disabling conditions, and do not have the leg strength to propel a manual chair with their feet. A person with full function of the arms and upper torso will generally be prescribed a manual chair, or find that their insurance will not cover a powerchair.
The user typically controls speed and direction by operating a joystick on a controller. Many other input devices can be used if the user lacks coordination or the use of the hands or fingers, such as chin controls and puff/suck scanners for those with C2-3 spinal cord lesions or head injuries. This controller is the most delicate and usually the most expensive part of the chair. Powerchairs can offer various powered functions such as tilt, recline, leg elevation, seat elevation, and others useful or necessary to health and function.
Powerchairs use electric motors to move the wheels. They are usually powered by 4 or 5 amp deep-cycle rechargeable batteries, similar to those used to power outboard boat engines. These are available in 'wet' or 'dry options; most these days prefer 'dry' cell batteries, and airlines will not allow the transport of 'wet' batteries. Many powerchairs carry an on-board charger which can be plugged into a standard wall outlet; older or more portable models may have a separate charger unit.
A basic standard manual wheelchair incorporates a seat and back, two small front (caster) wheels and two large wheels, one on each side, and a foot rest.
Wheelchairs are often variations on this basic design, but there are many types of wheelchairs, and they are often highly customized for the individual user's needs. The seat size (width and depth), seat-to-floor height, footrests/leg rests, front caster outriggers, adjustable backrests, controls, and many other features can be customized on, or added to, many basic models, while some users, often those with specialized needs, may have wheelchairs custom-built.
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 neck, mounts or carrying devices for crutches, walkers or oxygen tanks, drink holders, and clothing protectors.
Experiments have also been made with unusual variant wheels, like the omniwheel or the mecanum wheel. These allow more directional movement options. The electric wheelchair shown on the right is fitted with Mecanum wheels (sometimes known as Ilon wheels) which give it complete freedom of movement. It can be driven forwards, backwards, sideways, and diagonally, and also turned round on the spot or turned around while moving, all operated from a simple joystick.