Answers to basic Powerchair
This is pretty BASIC
stuff. I would expect any "expert" to get all of this easily. Lets get
something straight. Reading powerchair spec sheets, and knowing all their
"measurements" and going on some courses about trick seating and "options" wont
help you if you don't understand the basic requirements! These are here!
If you are an "expert" and
disagree with anything on this site I welcome the discussion!
A powerchairs maximum width should be the same as the person seated in it. Any
wider than that and it hinders mobility indoors. Any narrower than that and
there is nothing to be gained in doorways or in confined spaces. And it means
that space has been wasted that could have been utilized for batteries (range or
performance). Under no circumstances use the manufacturers claimed figures
as this usually is with a very narrow cushion... My own
powerchair is 25.2 inches
total WITH an 18 inch wide cushion.
The correct length for a powerchair is as short as possible with the distance
between two walls being limited by the occupants head, and feet while seated. If
there is any part of the powerchair behind them stopping them touching their
head on a wall then its simply too long. That means indoor mobility in confined
spaces is hindered. In MID DRIVE powerchairs this should include casters
extended to the "longest" direction. If you think this is not possible check out
my own powerchair. its 40 inches
total length. Under no circumstances use the manufacturers claimed figures as
this usually doesn't include foot riggings, or measures the rear casters in the
most "advantageous" position...
6 MPH for a powerchair with group 34 or 24 batteries and an
average weight outdoor user is best. 4 MPH for a chair with smaller
batteries like 50Ah or less. 8mph for very light users who don't expect all day
range or great torque. If you don't totally understand this then you have no
right claiming to be a professional! However less than 6 MPH is almost
unusable outdoors, and has safety implications even crossing a busy road. So
this means 6MPH and group 24 (34) batteries of around 70Ah are essential for any
serious outdoor use. So powerchairs that don't use batteries of this size are of
no use at all outdoors.
Control systems for a 6mph powerchair are borderline at 80 amps. 100 is better
for ramps or turning in difficult circumstances. Unless the user is very light.
Smaller systems are "OK" in slower powerchairs. But slower powerchairs do not
belong in the indoor/outdoor category at all. And not all control systems are
created equal. differences here
Programming a powerchair correctly for each user is absolutely essential. In
many cases this requires an OEM level programmer. I would estimate that 90
percent of users do not have their powerchairs programmed correctly for them and
that their health care professional hasn't a clue how to help or even knows they
could! Read powerchair programming here
Seat height affects many things relating to powerchairs. Here are a few
simple obvious affects:
a) swinging side to side in an ark
higher up above a powerchair on uneven outdoor surfaces is uncomfortable, but
worse it causes shear forces and pressure damage.
b) It also leaves the powerchair more likely to tip over sideways on a lateral
slope - trust me it hurts!
c) It also means that a powerchair wants to tip backwards easier on a ramp.
Meaning that the Centre of gravity (the user) has to be moved forwards making
the chair nose heavy on a level surface. Causing less ease of manoeuvrability,
making the chair physically longer, and eating battery power faster due to the
energy needed to turn increasing. So aftermarket seating that sits you
higher than stock is best avoided at all costs. Because it reduces your mobility
in a number of ways.
There are several affects
a) Puncture free or foam filled
tyres are harder to push so eat batteries faster. They therefore reduce range,
and further reduce battery longevity.
b) Puncture free tyres always give a harsh ride. This causes comfort, muscle
spasm, and pressure sore inducing shear forces. It also increases weight on the
drive wheels which hinders any suspension control and wastes battery power.
Wheel and caster sizes.
a) Casters have NO suspension. Our
world is VERY rough and uneven. 10 inch x 3 air filled casters are far superior
outdoors to anything else. That would be a 3.00 x 4 tyre. It has enough "give"
in its large sidewall to take away some of the vibration and shocks. This helps
prevent muscle spasm, vibration, (so your feet stay on the footplate!) and rides
over the uneven landscape well. They are "fat" enough to give some floatation on
sand, snow and mud when outdoors too. Provided that the chair is not "nose
heavy". Little weight should be on the caster wheels in a well designed chair.
Smaller, and solid casters are really not suitable outdoors at all. Unless you
accept the loss of comfort, and risk of problems and the reduced mobility.
Although smaller and harder ones are great indoors. But a well designed chair
will still be fine indoors with the larger casters. Most are not well designed
though. Punctures cease to be a problem completely if the chairs c of g is
rearward, as there is little weight on the casters. (rear wheel drive). And as a
precaution OFF ROAD puncture seal can be added too.
b) Rear drive wheels or Mid
drive wheels should offer floatation and comfort. They should have big sidewalls
and be very soft. For the real world is full of sand, soft grass, mud,
snow and worse and non of it is smooth! So they should be wide / fat balloon
style ideally. My own chair uses 6 inch wide ATV tyres on the rear. Its total
width is NOT any wider than I am, and under 25.2 inches total. That's narrow. A
clever trick with full sized batteries needed for all day 6 mph use.
Unfortunately there are no similar
powerchairs available yet, until the "experts" catch up! So you
are stuck with 3.00 x 8 tyres usually, which give a very harsh ride outdoors
even if the chair is fitted with "suspension" Never even look at a chair with
smaller drive wheel sized tyres and wheels than this for outdoor use. Thinks
like this are simply hopeless and
Batteries! The BEST quality group 24 batteries that you can buy have
neither enough power (amp capability) for ramps or turning id difficult
situations or enough range for an active heavy powerchair user to get on with
his day. And they will not last 1 year before replacement. Very expensive and a
pain in the butt. So any powerchairs with smaller batteries than 70Ah are
useless. That means much fancy seating, and almost all "small" cheap powerchairs
are a complete non starter...
There ARE NO CONTENDERS! The conflicting requirements of fat
soft comfortable outdoor "floaty" tyres, to give good off road and outdoor
performance on pavements and sand/snow and full sized batteries, for 6mph low
seat and all day range and the small 40 inch long (including everything) x 25,2
inch wide maximum defeats all the big manufacturers. There is simply no good
outdoor/indoor powerchair. So you need to compromise one way or another.
Actually that's a lie. My own
powerchair does all of the
above. But I built it myself and you cant buy one. One day the manufacturers
will catch up! But don't hold your breath! I did it because I was sick of
the experts lack of any clue! It suits almost every powerchair user in ONE