A basic manual wheelchair incorporates a seat, foot rests and four wheels: two, caster wheels at the front and two large wheels at the back. The two larger wheels in the back usually have handrims; two metal or plastic circles approximately 3/4" thick. The handrims have a diameter normally only slightly smaller than the wheels they are attached to. Most wheelchairs have two push handles at the top of the back to allow for manual propulsion by a second person.
Other varieties of wheelchair are often variations on this basic design, but can be highly customised for the user's needs. Such customisations may encompass the seat dimensions, height, seat angle (also called seat dump or squeeze), footrests, leg rests, front caster outriggers, adjustable backrests and controls.
Wooden wheelchair dating to the early part of the 20th century
Everyday manual wheelchairs come in two major designs—folding or rigid. The rigid chairs, which are increasingly preferred by active users, 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 as it moves. Welding the joints also reduces 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.
Many rigid models are now made with ultralight materials such as aircraft aluminium and titanium. One major manufacturer, Tilite, builds only ultralights. Another innovation in rigid chair design is the installation of polymer shock absorbers, such as FrogLegs, which cushion the bumps over which the chair rolls. These shock absorbers may be added to the front wheels or to the rear wheels, or both. Rigid chairs also have the option for their rear wheels to have a camber. Wheels can have a camber, or tilt, which angles the tops of the wheels in toward the chair. This allows for better propulsion by the user which is desired by long-term users. Sport wheelchairs have large camber angles to improve stability.
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.
Transport wheelchairs are usually light, folding chairs with four small wheels. These chairs are designed to be pushed by a caregiver to provide mobility for patients outside the home or more common medical settings.
Experiments have also been made with unusual variant wheels, like the omniwheel or the mecanum wheel. These allow for a broader spectrum of movement.
Wheelchair fitted with Mecanum wheels, taken at an exhibition in the early 1980s.
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.
Manually propelled
Manual wheelchairs are those that require human power to move them. Many manual wheelchairs can be folded for storage or placement into a vehicle, although modern wheelchairs are just as likely to be rigid framed.
Manual or self-propelled wheelchairs are propelled by the occupant, usually by turning the large rear wheels, from 20-24 inches (51–61 cm)in average diameter, and resembling bicycle wheels. The user moves the chair by pushing on the handrims, which are made of circular tubing attached to the outside of the large wheels. The handrims have a diameter that is slightly less than that of the rear 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 who can control the chair in this manner can climb and descend curbs and move over small obstacles.
Foot propulsion of the wheelchair by the occupant is also common for patients who have limited hand movement capabilities or simply do not wish to use their hands for propulsion. Foot propulsion also allows patients to exercise their legs to increase blood flow and limit further disability.
One-arm drive enables a user to guide and propel a wheelchair from one side. Two handrims, one smaller than the other, are located on one side of the chair, left or right. On most models the outer, or smaller rim, is connected to the opposite wheel by a folding axle. When both handrims are grasped together, the chair may be propelled forward or backward in a straight line. When either handrim is moved independently, the chair will turn left or right in response to the handrim used. Another alternative is a LeverDrive chair that propels the chair forwards by using a lever that is pumped back and forth.[6] Some chairs are also configured to allow the occupant to propel using one or both feet instead of using the rims.
Attendant-propelled chairs (or transport wheelchairs) 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, possibly within a hospital, as a temporary option, or in areas where a user's standard chair is unavailable. These chairs are commonly seen in airports. Special airplane transfer chairs are available on most airlines, designed to fit narrow airplane aisles and transfer wheelchair-using passengers to and from their seats on the plane.
Wheelbase chairs are wheeled platforms with specially molded seating systems interfaced with them for users with a more complicated posture. A molded seating system involves taking a cast of a person's best achievable seated position and then either carving the shape from memory foam or forming a plastic mesh around it. This seat is then covered, framed, and attached to a wheelbase.
Light weight and high cost are related in the manual wheelchairs market. At the low-cost end, heavy, tubular 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. Heavy unmodified manual chairs are common as "loaners" at large facilities such as airports, amusement parks and shopping centers. In a higher price range, and more commonly used by persons with long-term disabilities, are major manufacturer lightweight chairs with more options. The high end of the market contains ultra-light models, extensive seating options and accessories, all-terrain features, and so forth. Reclining wheelchairs have handbrake-like controls attached to the push handles or posts supporting the backrest which, when pressed by the caregiver, allow the backrest to recline from is normal upright position (at 90 degrees) to varying angles up to 180 degrees.
Electric-powered
An electric-powered wheelchair is a wheelchair that is moved via the means of an electric motor and navigational controls, usually a small joystick mounted on the armrest, rather than manual power. For users who cannot manage a manual joystick, headswitches, chin-operated joysticks, sip-and-puff or other specialist controls may allow independent operation of the wheelchair.
Other variants
A dynamic tilt wheelchair is one that can in which the seating surfaces can be tilted to various angles. This was developed by an orthotist, Hugh Barclay, who worked with disabled children and observed that postural deformities such as scoliosis could be supported or partially corrected by allowing the wheelchair user to relax in a tilted position. Invented in Kingston, Ontario, Canada, the early 1980s, the dynamic tilt wheelchair type is now manufactured by a number of companies and used all around the world. This revolutionary adaptation of wheelchair design provides individuals with very complex health needs the opportunity to be mobile.
A Standing wheelchair is one that supports the user in a nearly standing position. They can be used as both a wheelchair and a standing frame, allowing the user to sit or stand in the wheelchair as they wish. They often go from sitting to standing with a hydraulic pump or electric-powered assist. Some options are provided with a manual propel model and power stand, while others have full power, tilt, recline and variations of power stand functions available as a rehabilitative medical device. The benefits of such a device include, but are not limited to: aiding independence and productivity, raising self-esteem and psychological well-being, heightening social status, extending access, relief of pressure, reduction of pressure sores, improved functional reach, improved respiration, reduced occurrence of UTI, improved flexibility, help in maintaining bone mineral density, improved passive range motion, reduction in abnormal muscle tone and spasticity, and skeletal deformities
A bariatric wheelchair is one designed to support larger weights; most standard chairs are designed to support no more than 250 lb (113 kg) on average.
Pediatric wheelchairs are another available subset of wheelchairs. Hemi wheelchairs have lower seats which are designed for easy foot propulsion. The decreased seat height also allows them to be used by children and shorter individuals.
A knee scooter is a related device which may be substituted for a wheelchair when an injury has occurred to only one leg, below the knee. The patient rests the injured leg on the scooter, grasps the handlebars, and pushes with the uninjured leg.
A power-assisted wheelchair is a recent development that uses the frame & seating of a typical manual chair while replacing the standard rear wheels with wheels that have small battery-powered motors in the hubs. A floating rim design senses the pressure applied by the users push & activates the motors proportionately. This results in the convenience, small size & light-weight of a manual chair while providing motorised assistance for rough/uneven terrain & steep slopes that would otherwise be difficult or impossible to navigate, especially by those with limited upper-body function.