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PLEASE READ!
A more up to date version of these
pages now
lives
HERE along with reviews of power chairs and wheelchairs
UPDATE at last! I got bogged down in web building work, etc. Now LOTS more has
been done, updated June 4th (Page
4)
First I laid out all the bits I had, which means the
pair of ex wheelchair motors*, a new Penny & Giles 100 Amp Pilot Plus
power-chair controller from the same type of powerchair, and four brand new
trailer wheels and tyres bought from Halfords...
*That I took from my wheelchair because the things
were very clunky and the motor was "hesitant" at times... Nothing about 10 hours
work, new brushes, new cush drives and new gears wont fix! But they are not
"technically" available... And it would cost more than a new set of motors!
Still it CAN be done, I have ways...
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All photos are thumb nails and if clicked will open
a new window as they are all large clear images that may take time to load. That
way you can read this while it loads! This is the two channel 100 amp
"wheelchair" controller. It has in built mixing, temperature and current fold
back and many other programmable settings. It delivers a REAL continuous safe
100amps at 24 volts, in a controlled safe fashion. To change its settings you
need a special programming box called a PP1b (NOT a PP1a) Fortunately, I
have one of these too... This one is a spare one I happen to have. |
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At this time this device is
still supposed to be a 4 wheel drive long distance video camera
platform, controlled by radio control, and sending its picture back via
an on board transmitter to me! So I can see where its going on a small
TV screen. These are the pre cut bits that just arrived! (Although it
MIGHT just finish up a new wheelchair instead! With this in mind, I made
it the correct width (on the beer mat in the pub!) as I ordered the
metal. Total width across the tyres is 23 inches, same as my F55s
powerchair. |
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These wheels
were 350 x 8 tubeless tyres on steel 8" x 2" rims with four mounting
holes at 115mm PCD or 107.5mm radius if you prefer. After several days
staring at all the bits a cunning construction plan filtered in to my
brain... I wanted Tank steering, with chain drive to the wheels,
simple compact and elegant engineering construction. No yucky steel
brackets, added on bits etc, much thinking, but little cutting!!! I
chose these wheels because they are readily available, cheap, chunky,
strong, tubeless (less puncture problems!) and I spotted them in a local
car accessory shop... |
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Here the
spacers and the cross bars that join the gearboxes together are being
drilled and tapped M8 in my old lathe in my bedroom. The furniture
polish (Mr Sheen) is crap cutting lubricant...
Girlfriend is DEAD pleased! She LOVES finding metal swarf in bed and
stuck in her feet when she gets up... All had to be machined
alloys and stainless cap screws... No bodging here... Oh AND Cheapish!
OK, enough threading and turning... |
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I decided to
check out these 3 year old used wheelchair motors and look inside! They DIDN'T look like this! First I
stripped them and tipped about 2 cupfulls of black burned carbon brushes! And
rust... No wonder they were a bit hesitant, and noisy! Surprised they worked at
all... No room for anything to turn! If you have a powerchair that sees daily
use then you must blow the dust out of the motors and replace the brushes
AT LEAST annually. If not you are going to be stuck sooner or later. If you do
they may well last forever. A lesson
learned. Oh, you can just see my home made Gas Turbine's
tailpipe sticking out at the top right of the picture!
OK They were completely stripped cleaned in soapy
water, re-greased bearings, new brushes, and the commutator was cleaned up with
a bit of emery paper. Good as new!
Gearboxes were cleaned only externally, for now, but
I will be getting new internals, and new cush drives soon because they are
clunky with lots of backlash... These will hopefully come from Rebel Replicas.
In the meantime it will have to be noisy! (backlash from MANY wheelies) It will not break.
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Those buggered brushes...These are a
comparison, between the old motor brush and a new one. Some were much worse than
this one on the left but I threw them out before I remembered to get a
picture...
This whole project started as "something to do with
all the spare wheelchair bits" I had kicking around, and the fact that I have a
lathe in my room... Oh, and because I can... This has (or didn't have!) anything
to do with Robot Wars - the TV program. Although it may finish up this way. So
now I am thinking and still confused as to quite what I am building! Still Must go
on!!!
It also had to be as close coupled as possible
(wheels as close together as possible) so that the "tank style" steering
does not cause problems and is "smooth" and controllable. Too
far apart and it will struggle to turn.
About
this time I decided that it would also make a good powerchair base too for the
street... I am a wheelchair user! So we have a problem... And we have another
problem too! I thought I might fit a big flywheel type weapon and compete in
that Robot wars TV show! So now I need three of these things! OR one that will do all
three jobs... We will see what happens. |
OK too much brain work ,
my head hurts, time for some relaxation time. |
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Did I mention 4 wheel drive? Well for tank style steering to work you need 4
things:
- 4 wheel drive
- LOTS of torque
- Wide overall track compared to the wheelbase |
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This picture shows the NEXT larger taperlock fitting
sat on the shaft as well as the sprocket one.. This one will allow me to also fit a modified V-Belt
pulley. This pulley will have the "V" bit machined off, and four M10 holes
tapped so that I can bolt the wheel on!
This pulley is not shown here. This is how I intend to get power to the front
wheels, with a 19 tooth sprocket on both the rear and the front wheel shafts.
These shafts are "keyed" but this is a bad way to transfer a reversing torque
load. The sprockets (and the wheels) will all use these "taperlock" fittings.
These locate inside the sprocket, and clamp securely on to the shaft as a couple
of Allen keys are tightened up.
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Construction started!
The angle bits are already drilled, and the
following pictures show how the spacers, cross pieces, and side rails all fit
together using long 8MM bolts. The cross bits that go between the gearbox have
been tapped to take the M8 bolts.
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Another view so you can see what I am talking
about... This time with the threaded bar joining both sides. View as above - different angle. |
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Now much more built! Showing all four cross pieces,
and all four side rails fitted as well as a sprocket and chain. |
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A view with the bottom aluminium plate
fitted, and the wheels mounted on the motors, with the drive sprockets
for the front wheels. |
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This is in the wrong place on the page! Out
of sequence, blame the beer... |
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Showing how the front wheel axle and drive
chain/sprocket will mount etc... |
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Close up of the motor, sprocket mounted to
the shaft using a taperlock, and the modified pulley that now forms the
mounting for those cheap strong tubeless trailer wheels! |
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