Wheelchair Accessible Vehicle Ride Quality Forum
People buy a particular car for a number of different reasons. These range from its acceleration performance; its top speed (although this is possibly somewhat of an irrelevance with national speed restrictions in force); its fuel consumption figures; and, its handling. Handling covers a multitude of different things from cornering to ride quality. It is this last factor, ride quality that is particularly significant when thinking about a suitable vehicle to carry a wheelchair passenger.
One of the most praiseworthy adjectives someone is likely to use when thinking about ride quality is smooth. So with that in mind, let us think how this accolade can be achieved in a Wheelchair Accessible Vehicle.
Crucial is the position of the wheelchair in the vehicle and the configuration of the suspension. The manufacturer of any vehicle will have spent a great deal of time, effort and money in designing a vehicle where the passengers are positioned at the optimum position for the best ride quality. There are several other reasons, one other most notably being safety.
A graphic illustration of this point is the height of the wheelchair passenger in relation to the other passengers. It’s extremely unlikely; possibly even impossible, that the position will ever be lower than the other passengers. What is more common is that the position will be much higher. In such a situation there is going to be an adverse affect on the comfort of the ride due to the wheelchair passenger’s centre of gravity being much higher in the vehicle. No difference will be noticed when travelling along in a straight line, but it’s a different story when the vehicle goes around a corner. Without going into lengthy discussions on the physics which involves such things as levers, fulcrums, weights etc. just think of it as being like a ‘Merry-Go-Round’ where the further out you are from the centre, the more you will feel the force of gravity or ‘g’. The movement is often referred to as 'body roll', the amount of which will be dependant upon the rear suspension configuration.
I mentioned that there will be no discernable affect when travelling in a straight line if seated higher, but that’s not strictly correct. The affect I have in mind is not so much physical as sensory in that being seated higher in the vehicle is going to have an adverse affect on the passenger ‘seeing out’ our of the car as their vision is likely to be blocked by the headlining. Yes, this can be overcome by replacing the roof with a heightened structure with narrow viewing windows, but the result is a bit like looking out of a pill box and a less dignified looking vehicle!
Positioned in the same area as the other vehicle passengers has other added benefits, not least in being able to easily talk to one another without having to shout.
A final aspect, and one not readily obvious, is the affect the slope of the floor has on the ride quality; or more correctly the absence of a slope. This is one of those things that needs to be experienced to appreciate its significance, but suffice to say, our tests have shown that sitting in a chair on a sloping floor for a period of time can be extremely uncomfortable. So last but not least, the final quality of a WAV that helps to ensure a good ride is a level floor.