Drive Wheel Differences on Electric Wheelchairs

The drive wheels, the wheels connected to the motor, used to be at the rear of the electric wheelchair. The center of turning was behind the user, with most of the wheelchair and user seated to the front. This limited the environments in which a powered chair could function, primarily because of the overall chair length and turning radius.

Now drive wheelchair wheels come in three positions; rear-wheel drive, mid-wheel drive and front-wheel drive. Each have advantages and disadvantages. Keep in mind that each have their own driving/handling characteristics, as well as turning radii. The turning radius is determined by a measurement from the middle of the drive wheel to the furthest part of the chair, which may be to the front or the rear. Let's look at each of these types of electric wheelchairs.

Rear-Wheel Drive
This old standby is really one of the most stable chairs in most instances. However, going up steep hills will cause the chair to lean back on its anti-tip tubes to assist in preventing the chair from tipping backward. This type of chair has the highest top speeds available (about 6 mph). It also has the largest turning radius, beginning at about 33". If you have been driving a rear-wheel drive chair and plan to buy another type, keep in mind that the tie-down you use in your van will have to be re-made or replaced for the new style chair.

Front Wheel Drive
In this type of chair, the drive wheels are actually forward of where you sit. It is a very stable set-up for uneven terrain, up and down hills. Out of the three types, it climbs forward over small obstacles well also. Most of the chair is in back you, so when turning, you have to be aware of what is behind you. The driving characteristics can be compared to a forklift. The overall speeds are slower (about 5 to 5 ½ mph) because the front-wheel drive tends to "fish tail" at higher, more reactive speeds. The overall turning radius is about 25 to 28", depending on the manufacturer.

Mid-Wheel Drive
Your center of gravity is about even with the center of the drive wheel in a mid-wheel drive chair, so the drive wheels essentially are under the user. You end up with equal parts of the chair in front of and behind your body. This type of chair is maneuverable in small spaces, with a turning radius of 24 to 26", depending on the manufacturer. Overall speeds are limited to about 5 ½ mph. Another consideration is terrain. When riding on uneven terrain or up and down curb cuts with a steep transition, there is a possibility of getting "stuck" on the front or rear casters, suspending the drive wheels so they have no contact with the ground.