Glossary of Medical Terms

Powered Wheelchair Components

Frames - Many traditional-style models utilize the traditional cross-brace frame which allows the chair to be folded or collapsed for storage and transport once the batteries have been removed. Other traditional models and some power base chairs disassemble for transport. A number of chairs, however, are designed to be transported while carrying the user; consequently, they do not fold or disassemble.

Upholstery - for wheelchairs must withstand daily use in all kinds of weather. Consequently, manufacturers provide a variety of options to users, ranging from cloth to new synthetic fabrics to leather. Many manufacturers also offer a selection of upholstery colors, ranging from black to neon, to allow for individual selection and differing tastes among consumers.

Seating System - are sold separately from the wheelchairs themselves, as seating must be chosen on an individual basis. It is important when selecting a wheelchair or a seating system to ensure that the two components are compatible. Power base chairs, because of their more modular construction, frequently feature customized chair-style seating systems.

Brakes - Most powered chairs utilize a dynamic braking system in which the motor and brakes work together to slow and stop the chair when the joystick or other controller is released, and which automatically engages the brakes when the power is off or when the chair is not being powered in a forward or reverse motion with the controller.

Wheels/Tires - Power base chairs typically use four wheels of the same size, usually 8 to 10 inches in diameter. These chairs may have pneumatic, semi-pneumatic, or solid tires.

Footrests - A variety of footrest assemblies are available on both types of wheelchairs. They may be a rigid single unit, 90 degree-90 degree platforms, folding, flip-up, detachable, adjustable length, hemi- height, or have a combination of features.

Armrests - Armrests also come in several styles or with a combination of features. They may be full- or desk-length, or wraparound, and they may be fixed, removable, pivoting, and/or adjustable height.

Controls - Powered chairs generally include as a standard feature a manually controlled joystick to regulate the chair's speed and direction. However, most manufacturers offer customized control options to accommodate the varied abilities of the user, including sip-n-puff systems, head and chin switches, push-button controls, trackballs, and tillers. Many chairs also have programmable control features which allow the user or a dealer to adjust or set the chair's speed and control limits as the user's abilities change.

Drive System - the means by which power is delivered to the chair's wheels. Standard drive systems include gear drive, direct drive, and belt drive. The type of drive system affects the power available to propel the chair and the amount and type of maintenance the chair requires.

Batteries - are a determining factor in the range and power of a powered chair. Generally, the larger the chair's batteries, the greater the power and the longer the chair's range between charges. Many chairs require two rechargeable 12-volt batteries. Most wheelchairs utilize U1, group 22 or 24 batteries, although other batteries are also used. More manufacturers are designing chairs around the group 24 battery because it affords a longer range. The type of battery required is also an important consideration in terms of safety, maintenance, and transport. Powered chairs may utilize lead acid, gel cell, or sealed wet batteries. Gel cell batteries require the least maintenance and have less danger of leaking than do the other battery types. Gel cell batteries are also required by a number of airlines when transporting powered
chairs.

Special Powered Features - Powered chairs may offer specialized powered features to meet the user's needs, either as customization or options on a standard chair or as a chair designed specifically for a particular purpose. Among the available features are elevating and lowering seats, and reclining and/or tilt-in-space seats. Specialized chairs have the capacity to raise the user to a standing position, to negotiate stairs, or to be used as a lift or in transferring.