More MS news articles for May 2000

Powerchairs 101

By Mark E. Smith

Ready to trade in his 1986 powerchair for a millennium model, John went to see his local wheelchair dealer. "Would you like front-wheel, mid-wheel, or rear-wheel drive?" asked the salesman.

"Huh?" replied John. "I just want a good powerchair for everyday use."

"Sixty-, 70- or 80-amp electronics? Rehab, power or sport seating? Eight-inch, nine-inch or ten-inch casters? Remote or integrated controller?" the salesman continued, flipping through a foot-thick binder bulging with powerchair options lists.

John quickly learned that today's powerchairs offer a dizzying array of technology choices, leaving many of us overwhelmed when purchasing a new chair. Yet, as with shopping for cars or computers, once you understand the technology and the jargon, the process goes from frustrating to fun.

Options and Extras

Powerchair models used to be clearly defined for indoor or outdoor use. Nowadays manufacturers use base products that can be equipped for your specific needs, making it imperative to select the correct features for your lifestyle. Someone who lives on a ranch might select the same powerchair as a schoolteacher, but by selecting the appropriate features, their chairs change to fit individual needs. Before considering powerchair features, consider your lifestyle, then select the technology that best meets your intended uses.

Drive Platforms

For four decades, rear-wheel drive has been the dominant type of powerchair, and while it's still an industry staple, mid-wheel and front-wheel drives have emerged as popular alternatives to the traditional powerchair platform  Each platform caters to different types of users, providing unique handling characteristics.

Rear-Wheel Drive

Among the most practical designs, powering the rear wheel creates a chair A rear-wheel drive powerchair. that naturally rolls straight. For users with limited hand control or who use head controls to steer, a RWD is a great choice, requiring less effort to drive than mid-wheel and front-wheel drives. Because RWDs are powered in a conventional fashion -- from the rear, like most vehicles -- they can safely obtain much higher speeds than the other powerchair designs. Fast RWDs range from 8 to 12 mph.

RWDs aren't without drawbacks, though, as they take a lot of room to maneuver indoors and feature small casters in the front that can catch on obstacles and sink into soft surfaces outdoors.

Mid-Wheel Drive

The most recent addition to powerchair design, mid-wheel drives have large A mid-wheel drive powerchair. drive wheels centered under the user. The MWD platform provides a chair that requires less space to turn -- it pivots close to its center -- making it less cumbersome indoors. But because as much as 80 percent of the user's weight is balanced over the centered drive wheels, MWDs are notorious for violent, forward pitching when decelerating or traveling downhill. Some manufacturers have moved to six-wheel designs -- placing small stabilizing casters on the front and rear of the chair to eliminate pitching -- but that technique produces a powerchair that's easily hung up on outdoor obstacles. Other manufacturers have opted to move the drive wheels slightly forward of center and use front elevated anti-tip wheels, which creates a well-functioning chair under indoor and outdoor conditions. Front anti-tips actually outperform RWDs outdoors because there are no front casters to catch on obstacles.

Unlike RWDs, MWDs don t naturally roll in a straight line. The chair is pulled instead of pushed, making it prone to veering side to side, so speeds over 7 mph aren't an option.

Front-Wheel Drive

Popular in Europe, front-wheel drive powerchairs offer more stability than A front-wheel drive powerchair. mid-wheel drives and better off-road performance than rear-wheel drives. They easily surmount obstacles that stop front casters. Because FWDs steer from the front end, many users find them easier to maneuver indoors than rear-wheel drives.

FWDs, however, like mid-wheel drives, suffer from directional instability, making them wander side to side at high speeds, so most FWD s are painfully slow -- typically 5 mph -- in comparison to rear-wheel drives.

Gotta Have Suspension

Among the best powerchair advancements of the past decade has been suspension, now a must-have item for most powerchair users. While suspension does soften a chair's ride (and manufacturers claim it reduces muscle spasms), its main purpose is to enhance handling on rough terrain, maintaining traction and stability.

Some manufacturers use rubber dampers and call them suspension, but on a quality chair you'll find a dampened spring suspension system that offers several inches of travel.

Accessorize: Wheels and Casters

Much like wearing the correct shoes for an occasion, you should pick the appropriate wheels and casters for your lifestyle. You don't want to end up with high heels when you need hiking boots.

Drive Wheels

The drive wheels deliver power, so they must be large enough to provide adequate traction and obstacle clearance but not so large that they interfere when maneuvering in tight quarters.

General rules:


A wide wheel -- 3 to 4 inches -- provides greater traction on outdoor surfaces, but a narrow wheel - 2 inches -- makes for an easily maneuvered chair indoors, so give considerable thought to your environment when selecting wheel sizes.

Casters

Caster size dictates a large portion of your chair's performance. If you often use your chair indoors or require a chair that turns in the least amount of space, choose 8-inch casters. Nine-inch and 10-inch casters work remarkably better outdoors but are much wider, requiring more room to pivot. In recent years, 9-inch casters have gained in popularity, as they're large enough to plow through muck and aren't too clumsy in cramped spaces.

Give Your Chair a Buzz

The heart of a powerchair is its electronics. Choose the right components to maximize your chair's performance.

Controllers

The controller, commonly called a "circuit box," is the powerchair's brains. Controllers typically come in 50-, 70-, and 80-amp sizes. The higher the amp rating, the more power your chair has. Indoor or light-duty chairs run well with 50-amp controllers, but if you're a heavy outdoor user, you'll want a 70- or 80-amp system.

Controllers come in two styles, integrated and remote. Integrated controllers share the joystick housing, meaning that the circuit box and joystick hang on the side of the chair. Fifty-amp controllers are commonly integrated and work well, but they are bulky and inflexible for plugging in different joysticks. Remote controllers feature a separate housing for the controller and joystick, creating an adaptable system. Remote controllers can be placed out of sight for a sleeker look, and various joysticks can plug in to them, tailoring the system to your needs.

Joysticks

There are over a dozen hand controls on the market, all steering the chair in an almost identical way by using a joystick. The hand controls differ in the way the user controls the chair's functions, including power and speed. Hand controls traditionally feature toggle switches, good for those with limited hand use, or flush-mount touch-pad keys. Recently, several manufacturers have marketed hand controls in which the chair's functions, including power seat adjustments, are controlled through the joystick itself, eliminating most switches and touch-pad keys. Custom steering interfaces allow the user to steer using his breath, head, feet, elbows and so on. Try the different styles of controls and find the one that's most comfortable for you.

Programming

Even the least expensive chairs are programmable, meaning that the electronics can be adjusted, tuning the chair's handling characteristics to your likes. Programming is accomplished through a plug-in remote that allows you to adjust acceleration, deceleration, top speed, turn rate and joystick sensitivity. When you first receive your new chair, you should take time with your dealer to adjust the programming to your wishes.

The Good Seats

Half of a chair's success comes from its seating. Beyond the obvious realm of comfort, proper seating provides increased positioning and balance and reduces fatigue and muscle spasms. Fortunately, most manufacturers today offer a minimum of three seating types on their powerchairs, allowing you to equip your chair with the one that s right for you.

Standard Seating

If you purchase a low-end powerchair, it will come with standard seating, consisting of a sling or rigid seat base and a sling backrest (the generic seating found on hospital wheelchairs). Standard seating may be fine if you only use a powerchair part time, but if you re a full-time user or have special positioning needs, consider opting for a more advanced seating system.

Rehab Seating

Despite its clinical name, rehab seating is the most functional seating system on the market and now comes standard on some powerchairs. Many users require pressure-relief cushions and custom back supports, and rehab seating, with its adjustable base frame, allows for the installation of a wide range of aftermarket seating products. Rehab seating also features power options, including tilt and recline. If pressure sores are a concern, tilt-and-recline seating is highly recommended. Power rehab seating, however, is very expensive, adding as much as 75 percent to the base price of a powerchair. Nevertheless, considering that it may protect your health, it's among the best investments you can make.

Sport Seating

A combination of form and function, sport seating resembles a sports car seat, with a high backrest, side bolsters and flip-up armrests. Sport seating looks great -- there's no "wheelchair" -- but it's not nearly as adaptable as rehab seating. Some manufacturers are introducing sport seating systems with removable upholstery and padding, which allow you to use pressure-relief cushions while retaining a sporty look -- comfort and class. The Perfect Set of Wheels

Take all this and do some more homework before you buy. After John did his homework, he ended up with a gloss black mid-wheel drive that, he boasts, "turns on a dime indoors and climbs mountains outdoors." With knowledge of powerchair technology and how it works in conjunction with your needs, you can configure your perfect set of wheels and take your mobility to a higher level.