What is the BEST powerchair drive base for you?
One of the many questions and uncertainties surrounding an individuals first or sometimes second powerchair purchase is what drive base to choose. By drive base I mean front-wheel drive (FWD), mid-wheel drive (MWD) and rear-wheel drive (RWD). Each one has it’s own unique driving characteristics and today I will do my very best to describe them to you. Before this though I’m going to briefly explain to you how you can tell what chair is what as it can be a little confusing. The basic rule of thumb though is wherever the large drive wheels are is where the drive is coming from.
LARGE WHEELS AT THE FRONT = FWD
LARGE WHEELS IN THE MIDDLE = MWD
LARGE WHEELS AT THE REAR = RWD
REAR-WHEEL DRIVE (RWD)
Lets start with RWD as this particular drive base is where it all began. Almost all powerchairs are powered by two motors with the only exception being a four wheel drive chair such as the Extreme X8 (https://clinicalmobilitysolutions.co.uk/all-terrain-powerchair/) . The position of the motors is what determines the drive style. Therefore with a rear-wheel drive (RWD) base the motors and the main drive wheels are at the rear. The way in which a powerchair moves is down to the how the two motors/wheels work together. When driving in a straight line, the motors run at the same speed however when turning they will operate at different speeds with the outer wheel turning faster than the inner wheel. For sharp turns the inner wheel will even stop completely to create the sharpest possible turn radius.
A RWD chair can be great for outdoor, straight line performance and can have similar characteristics to driving a car so for some it maybe easier to convert across if you’ve been used to driving car or even if you’re upgrading from a scooter.
The negatives of a RWD is down to it’s fundamental design. As I mentioned the straight line performance is good but due to a lot of the weight being at the rear, the front end can be extremely light and therefore the steering and control over slightly rough terrain or inclines can be questionable. Not only that but with many RWD’s the drive wheels are often situated behind the seat itself. Meaning that there can be very little traction and attempting ramps or sharp turns can result in the wheels spinning up and losing grip. Even more so when the surface is damp.
MID-WHEEL DRIVE (MWD)
MWD powerchairs are currently the most popular drive choice on the market today. They are almost a ‘jack of all trades’ kind of chair. The motors themselves operate in the same way, working together when driving forward and then stop or go against each other to complete a turn.
It’s the drive wheel position and the castors/castor arms around them that really set MWD apart. Because the drive wheels are directly centred the turning axis is also exactly in the middle of the chair. Meaning that there is the same amount of the base in front of you as there is behind you. As for the castor arms/castors, these act to support and balance the frame, but they also have the ability to articulate and move independently to each other. This allows the chair to accommodate varying terrain and tackle inclines without losing any contact with the ground thus creating fantastic traction and stability. All the weight is directly passing through the main drive wheels giving the chair the best possible grip. The COG also benefits the powered functions as it keeps the chair balanced throughout a range of movement.
There aren’t too many negatives with this drive base. However you will need to adjust to the sensitivity when driving in a straight line. Also if you’re operating the chair in an attendant position, you may find it a bit of a challenge initially.
FRONT-WHEEL DRIVE (FWD)
The last drive profile out of the three is front-wheel drive (FWD). Following on from the other two, this drive setup is once again designed to stabilise both the seating system and the base by counteracting the weight, with the clients load at the rear and the main drive wheels at the front.
By having the drive forward of the seating system it allows the chair to perform in certain areas that the other two cannot, well not as well at least. The main benefits would be kerb climbing performance, good turn rotation, posterior tilt and when someone wishes to stand. The idea is that whenever any weight is transferred forward, it is then supported by the drive wheels and axle.
The driving characteristics can be a little challenging to get used too as the turning sensitivity is heightened and you’ll have to adapt to the idea of having most of the chair behind you. Once you’ve done this though, it can be a very enjoyable drive and can outperform other chairs in the areas previously mentioned.
I hope this has supported or widened your knowledge and ultimately aided your decision in your next powerchair purchase. For any further information on any of the chair types mentioned, please get in contact either through the website or contacting the office directly.