Types of Wheelchairs
There is a wide range of wheelchairs because there is a wide range of disabilities and because different users have different preferences.
Manual wheelchairs are those moved by the user or an attendant. The self-propelled chairs usually have rear wheels of between 20 and 26 inches in diameter fixed to an axle and positioned so that users can move them by pushing down or pulling back the push rims. The users can therefore travel forward and backward at speeds dictated by the amount of force they are able to apply.
By controlling the push rims, users can also turn left or right and negotiate small dips and rises in their paths. Manual wheelchairs are best used by people with good muscular strength and coordination in their arms and shoulders.
Alternative methods of propulsion include foot pedals and levers worked by hand.
Manual Transit wheelchairs
Manual transit chairs generally have small rear wheels without push rims. These wheelchairs are most likely to be seen in buildings such as airports and hospitals where porters act as attendants. These are also called manual transfer chairs.
Power (Electric) Wheelchairs are also called “motorized wheelchairs” and sometimes abbreviated EPW (electric powered wheelchairs). These chairs are almost always equipped with electronic control systems to aid in steering and velocity. Individuals too weak to maneuver a manual wheelchair benefit from power chairs, as do individuals with heart and/or breathing conditions. There are power wheelchairs made specifically for indoor and outdoor use and some designed to be used for both.
Electric powered wheelchairs are ideal for anyone who does not possess the strength or ability to cope with a manual chair. (Many people own and use both manual and electric chairs.) Rechargeable batteries mounted under the seat supply power to electric motors that drive either two or all four of the wheels. As with a car, the different drive train arrangements determine the way that the wheelchair moves and manoeuvres. It is important to know for what conditions a chair is designed. If you take a chair that was designed for indoor use outside on rough terrain, you run the risk of damage to the frame, front forks, and motor. The wheelchair industry has standards for brake efficiency, energy efficiency, overall size, speed and acceleration, impact testing, obstacle maneuverability, and control system ergonomics.
The batteries come in three types: wet-cell, gel-cell and AGM (absorbed glass mat).
- Wet-cell batteries are the lightest, cheapest and least likely to be overcharged. They tend to leak, however, so cannot be taken on a plane.
- Gel-cell batteries are heavier but do not leak. They last longer than wet-cell batteries and are accepted for air travel.
- Absorbent Glass Mat (AGM) batteries are heavy and expensive, but they are suitable for airplanes, are shock-resistant and leak-proof, and do not require maintenance.
Older models of wheelchair batteries were charged by a separate unit, but most modern wheelchairs can simply be plugged into an electric socket for recharging, using a power rectifier like ones used to charge computer batteries.
There are options for managing the direction and speed of electric wheelchairs. Many have a small joystick mounted at the end of an arm rest or on a bar that swings in front of the user. Others have tubes into which the users blow or suck to control the chair’s movements. Having a power source on-board the chair allows designers to put in other features that take advantage of that power. These include:
- tilting mechanisms;
- reclining backs;
- seat, leg and arm elevators.
Most of these functions are controlled by small electric motors and allow users to make themselves as comfortable in the chair as possible. More on power vs. manual chairs.
Wheelbase or Scooter
A wheelbase chair, otherwise known as a scooter, has four small wheels extending from a low platform. The type of chair mounted on this platform varies according to the disability and needs of the user; some are even molded from a cast taken of the user’s most appropriate sitting position.
One advantage of the wheelbase machine is that the chair can swivel and allow the user to mount and dismount from either side. A disadvantage is that the user must maintain a rigid posture when driving the scooter. This means that wheelbase chairs are rarely suitable for the severely disabled.
The controls of the wheelbase chair are mounted on a frame that curves upward from the front of the platform to a height and position convenient for the user. A horizontal steering bar is attached across the top of the frame.
Since the 1970s, disabled athletes have had an increasing array of specialized wheelchairs to help them achieve the most from their chosen sport. These chairs can look very different from each other, but what they usually have in common is
- lightweight frames made from composite material;
- solidity (which means that they do not fold); and
- enhanced stability for sudden turns (this is achieved by using angled wheels).
Sports wheelchairs or recreation wheelchairs are specially designed for athletes with disabilities who are competing in sports that require agility and speed such as basketball, tennis, rugby or racing. These very specific chairs usually are not used in everyday life.
Depending on the sport, the chairs vary in design. The handcycle replaces the conventional bicycle with hand-powered pedals instead of leg-powered pedals. Court chairs (for basketball) come with a variety of features including: front bumpers, wings, spoke protectors, castor protectors, adjustable trick footrests, and more. Racing chairs designed to go fast in road races have low cross section and sometimes variable gearing. All terrain wheelchairs enable exploration of off-road, unpaved, bumpy, gravel areas.
Stand-up wheelchairs are fitted with hydraulic pumps that lift and tilt the seat, thereby enabling the user to "stand up" and yet be fully supported. This is an invaluable feature if the user needs to reach an item on a shelf either at home or while out shopping. Related: commode wheelchairs.
A number of wheelchairs have been designed with the ability to climb stairs. These sometimes include:
- Battery-operated supports at the back that act as stabilisers as the chair climbs.
- A series of flexible wheels turning within rubber tracks that grip the steps.
- Independent stair-climbing wheelbases onto which the wheelchair is fastened.
Most stair-climbing chairs still require a separate human attendant to operate. Alternatively, the wheelchair user must be able to grasp a suitable handrail.
A beach wheelchair is recognizable because of its broad wheels that enable it to ride smoothly over sand without sinking. Some beach resorts now provide not only wheelchair accessibility but also offer beach wheelchairs to disabled clients.
Conventional wheelchairs will not safely bear a weight greater than 250 lbs. A bariatric wheelchair, however, can accommodate someone as heavy as 1000 lbs. The weight capacity of bariatric chairs and the seat measurements vary so consult the manufacturer’s literature for their guidelines.
Pediatric wheelchairs are designed for disabled children. The chairs are not just smaller than the adult wheelchairs; some designs take into account the restlessness of children.
Snow wheelchair, from http://www.flickr.com/photos/8127509@N04/2333036875
from Flickr user mediadeo. Used under Creative