Page 7 - Mobility Management, April 2019

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Understanding PWC Drivewheel Options
Arriving at your wheelchair clinic today are three clients, each ready to be evaluated for a new power wheelchair.
Client #1 is a long-time power chair user who’s active in his urban community and enjoys wheeling through town to get to the office, run errands at lunch, and watch his son’s soccer games after work.
Client #2 will be a first-time power chair user. She just moved into a new apartment with an accessible entry and doorways, though some of the living spaces are a bit tight.
And Client #3 lives in a rural environment that presents with obstacles — fallen tree branches, soft soil — that need to be overcome daily.
Those are the preliminary notes you’re provided. The seating and mobility team at the clinic wants to know which type of power chair would be best: “Should we try a mid-wheel-drive chair? A front-wheel drive? Rear-wheel drive? Where do we start?”
Front, Mid, Rear: Their Strengths & Weaknesses
No single drivewheel configuration works for every client, and a client’s diagnosis, disease progression (if progres- sion is expected), medical history, functional goals, secondary conditions, positioning needs and additional equipment — just to name a few considerations — will also impact the wheelchair team’s ultimate choice.
But as a starting point, it’s helpful to understand each configuration’s strengths and weaknesses as you start your search for the best solution.
With its drivewheels positioned up front, the front- wheel-drive power chair is designed to tackle obsta- cles head on and “climb” over them. But up-and-over climbing isn’t this configuration’s only specialty. Due to the positioning of their wheels, front-wheel-drive chairs can also provide optimal space for lower-extremity posi- tioning.1 This configuration is also known for being stable on soft or uneven terrain. A possible front-wheel-drive disadvantage: possible “fishtailing” especially at higher speeds, due to the relative lack of weight on the rear portion of the chair.2
Mid-wheel-drive is known for its maneuverability, which is especially prized in tight spaces. Thanks to
its drivewheel location in the middle of the chair, this configuration provides smaller turning radiuses, and
the mid-wheel-drive configuration is considered the most intuitive for many clients to drive.3 A potential
disadvantage:
Because the drive-
wheels are in the
middle of the chair,
the chair can “high
center” on uneven
terrain. That means
the chair can
become stuck on its
front and rear casters,
with the drivewheel
losing contact with the ground.
For a considerable portion of power chair history, rear- wheel drive was the only configuration — and for some power chair users, particularly those with a long history of rear-wheel-drive use, this venerable configuration is still the favorite. Rear-wheel drive is historically known
for power and speed, and for stability at higher speeds, because so much weight is close to the drivewheels.4 Rear-wheel drive’s biggest drawback is its longer wheel- base, which requires more room for turning and can be tricky to maneuver in smaller spaces.
Every Client Is Different
So, what are the best power chair configurations for Clients 1, 2 and 3? Is rear-wheel drive best for the dad who covers a lot of ground every day? Is mid-wheel drive best for that new user with the small apartment? Is front- wheel drive best for the rural user who regularly needs to climb over obstacles?
As with any complex rehab technology situation, it depends. So many other factors need to also be part of that drivewheel configuration discussion. But knowing the strengths and weaknesses of each configuration moves the entire team closer to choosing, building and fitting the optimal power wheelchair for any particular client. Happy rolling! m
Sources & Resources: 1. Numotion — https://www. numotion.com/blog/october-2018/nu-digest-select- ing-the-right-wheel-configuration; 2. Spinlife — https:// www.spinlife.com/en/drivewheeldifferencesonelectric- wheelchairs2.cfm. 3. Mobility Management — https:// mobilitymgmt.com/articles/2010/07/01/power-chair- drive.aspx?m=1. 4. Muscular Dystrophy Association — https://www.mda.org/quest/article/front-middle-or-rear- finding-power-chair-drive-system-thats-right-you
A power chair’s turning radius is an important indoor consideration.
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