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ULTIMATE ACTIVEWEAR

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By GTK
Nov 16, 2017
Power wheelchairs

Drive Wheel Position on a Powered Wheelchair

One of the most significant factors to consider when selecting the right power wheelchair is the wheel position. It affects the maneuverability of the wheelchair, along with suspension, stability, obstacle climb and traction. The drive wheel location is described in relation to the user’s centre of gravity.

A rear wheel drive power chair positions the client’s centre of gravity ahead of the drive wheel. A centre or mid-wheel drive chair has the client’s centre of gravity somewhere over the drive wheel. A front wheel drive wheelchair has the client’s centre of gravity well behind the drive wheel.

The following chart describes how the drive wheel position relates to the performance of the wheelchair. This is an indicative guide only and should be considered in conjunction with other specific wheelchair features and client needs.

 

Performance Rear Wheel DriveCentre Wheel DriveFront Wheel Drive
Manoeuvrability (turning radius):
Described as the distance between the turning centre of the wheelchair and the most extreme point on the wheelchair
The front end of the wheelchair swings in such a way that the user must drive through the doorway before they begin to turn. Users must also hug the outer wall when turning into the door space. Although this has the largest turning footprint, it may assist clients who need to see more of the chair in front of them in order to perceptually determine distances and turning space. The smallest turning circle option as the user’s centre of gravity is closest to the chair’s centre point. As a result it is considered more intuitive for the user.
Users drive down the centre of the hallway and turn once their body clears the doorway frame.
The back end of the wheelchair swings during turning. The front drive wheel must clear the doorway before the turn can commence. This style of chair is more challenging for clients with cognitive or perceptual difficulties.
Stability and suspension:
Described as the shock absorption and wheel contact on uneven surfaces. Stability is increased with a larger base of support.
Very stable as the user’s centre of gravity sits within the drive wheel and front castors. Rear anti-tip wheels are often dynamic and further enhance the chair’s stability.Considered to be least stable when gravity and uneven surfaces are introduced. Users sit over the drive wheel offering less shock absorption. Very stable as the clients centre of gravity sits within the drive wheel and rear castors.
Traction:
Shifting the client’s centre of gravity of the drive wheel will increase traction. Be sure to consider clients body mass, weight, amputations and thickness of seating.
Most beneficial on inclines as centre of gravity shifts towards the rear. Need to ensure there is not too much weight over the front castors as it will cause a dragging affect. Strong consideration of wheelchairs with centre of gravity adjustment is desirable. Most beneficial on level surfaces as user’s centre of gravity is over the drive wheel. Critical to consider all environments client will travel to ensure traction is not compromised over inclines/declines.Most beneficial on declines due to larger drive wheel positioned forward to centre of gravity. If centre of gravity is well behind the drive wheel the front wheel may not grip, especially up hills. Strong consideration of wheelchairs with centre of gravity adjustment is desirable.
Obstacle climbing:
A chair’s ability to climb. Will also be affected by motors, programming, size of castor and footrest height.
Dynamic anti-tip wheels will allow the chair to be stable when climbing an obstacle by keeping all wheels in contact with the ground. Climbing ability will be affected by the axle height of the front castor/stabiliser. May be a challenge for kerb gutters.The larger drive wheel should allow for a smoother climb across obstacles.
Maximum speed and directional stability:
Wheelchairs will always tend to veer, regardless of the user trying to drive straight; the amount of self correction required via the joystick.
Directional stability increases as the speed of the chair increases. Good for outdoor use when higher speeds and stability are required.Directional stability will vary depending on whether the wheelchair base is set up more as a front or rear wheel drive.Directional stability decreases as the speed of the chair increases. May be difficult to maintain high speeds for clients with alternate controls such as head and chin controls.

GTK supplies the Quantum, Permobil, Invacare, Magic Mobility and Ottobock range of powered wheelchairs. Our extensive range allows us to find a suitable solution for your powered mobility needs. For further information on the range call and speak with your sales consultant.

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