Necessity the mother of invention.

[xelasnave]

I use a "walker" these days cause my legs, notwithstanding a successful operation on my back that kept me out of a wheel chair, are not flash.
It has four little wheels, a seat and storage.
It is great.
When I knock up I can take a seat and gets the shopping to the car.
So I thought it would be great if it had a platform on which I could stand and with some motors I could move along under power... Standing or seated.
So I have built a proto type using two cordless drills as power.
I have put in bike sprockets to gear down and sortta works but throws the chain because I need bearings at a point that I can't figure how to include.
But I don't think anyone else has made similar as nothing on utube.
I don't what to make a million, in fact I hope someone takes the idea and makes their fortune...I certainly would buy one rather than build one.
So it is an I'll wind that does not blow some good.
The main problem seems to be gearing as all indications are that the minimum speed will be to fast for someone like me.
Alex

[OzEclipse (Joe Cali)]

Alex,
As soon as I read drills I thought, "too fast." So the rest of your post didn't surprise me.

Drill motors turn at a few thousand RPM and have about a 4:1 gear and then run at 450-1000RPM.

I suggest you use a moderately highly geared DC motor say 20 RPM and control the motors with pulse width modified dc motor speed controller circuits.

gearhead DC motor
http://www.ebay.com.au/itm/Metal-Rev...z1k-gIT21n5lIw

dc motor speed controller
http://www.ebay.com.au/itm/12V-40V-1...4AAOSwdIFXyP2F

cheers

Joe

[xelasnave]

Thanks for your guidance Joe.
Alex

[xelasnave]

I calculate the wheels should rotate around 70 rpm That should be a slow walking speed.
I was working on the basis that at 1000 rpm thru the 4 to 1 (as I figured from looking at the drills gears) then added a 3 to 1 reduction may come close. It may but until I sort the chain throwing I won't know.
Anyways its a proto type but I became so obsessed with the idea I just had to start something.
And its got my mind off the big problems I am dealing with daily.
I overcame the biggest problem which was to make it collapsible.. Took ages to find a solution.
I can add a gear box (2 more sprockets) to make the wheels slower.
Alex

[silv (Annette)]

stop it down to sideral speed and you can ...

sorry

[xelasnave]

Looking at hub motors as well.
$100 each approx but come fitted in a wheel which solves drive connection.
It would be easy if I had a work shop a welder etc but its a kitchen table job.
Alex

[silv (Annette)]

you might be looking at it the wrong way.
whatever you do it'll bear down on the frame and gears and whatnot.

my mom pushed a lightweight wheelchair to keep her balance when walking.

my suggestion is therefor: have a look at modern carbon fibre --> wheelchairs--< and then start thinking about motorizing it.
What do you think?

After I made my stupid joke about sideral speed, I did penance and googled zimmer frames and rollators but could not find any with motors.

[raymo]

What about using 18v Lithium battery powered variable speed hand drills; lots of torque, and you could control the speed by mounting one trigger control
for both motors adjacent to the hand grip. Both motors could be powered by a single battery of whatever Amp/hourage you desire.
I think the gearing arrangements would be pretty simple too. It may not even need any differential gearing, 1:1 may be o.k.
raymo

[silv (Annette)]

Ha!
I came across the prototype of Ello through a friend. A rollator with motor to ease pushing up a hill. Too weak to sit in and drive.

Zinger makes a foldable wheelchair which you can probably alter to fit your needs.

And then there's the RehaCare fair in Dusseldorf/Germany.

Would you like to have a look through the exhibitors and products?
I didn't browse through them, feeling my penance is done.

[xelasnave]

Hi Annett
The current build is to see how the concept works, assuming I get the thing to work.
You know many what seem like good ideas may not cut it in the real world.
I enjoyed your joke by the way.
I decided on this because I could not lift a wheelchair into the car ...and it did not have a motor.
Moreover the geometry of these frames really is cool...you need to be there to appreciate how great they do their job.
Thanks for your input.
Alex

[xelasnave]

Originally Posted by raymo

What about using 18v Lithium battery powered variable speed hand drills; lots of torque, and you could control the speed by mounting one trigger control
for both motors adjacent to the hand grip. Both motors could be powered by a single battery of whatever Amp/hourage you desire.
I think the gearing arrangements would be pretty simple too. It may not even need any differential gearing, 1:1 may be o.k.
raymo

I am using 18 vlt cordless drills.
Using the drill housing for battery, motor and controls.
At the moment two systems. The thought of putting one side in forward and the other in reverse and doing spins on the spot appeals.

I cut the handle fitted bolts in resin for an easy mount system. Same with the battery ..that part fitted a bolt in resin an easy set up.Looks cool.
I have impact drills but no adjustment of torque.
I introduced gearing to slow it down and for pulling power.
When further develope it I will have one control for standing and one for sitting. Placement of controls took a lot of sitting standing on the thing but I have a near perfect positioning I believe.
Not having a welder I had to fit the drive shaft ( a standard impact drill socket thingy) and sprocket in fiber glass using toilet rolls for a mold and they distorted leaving things not perfectly centered which contributes to the chain throwing.
However there is flex in the system which when eliminated should see the chain staying in place.
If not I will have to remake the drive sprocket system and use PVC pipe as a solid mold.
The drive wiggles and I need a bearing for the system ..I have an idea how to do it but could not buy a suitable bearing today.

Alex

[xelasnave]

Still tired from the trip down yesterday so may have to rest up tomorrow ..jet lag..er car lag hits me the day after I arrive.
Alex

[xelasnave]

Originally Posted by silv

Ha!
I came across the prototype of Ello through a friend. A rollator with motor to ease pushing up a hill. Too weak to sit in and drive.

Zinger makes a foldable wheelchair which you can probably alter to fit your needs.

And then there's the RehaCare fair in Dusseldorf/Germany.

Would you like to have a look through the exhibitors and products?
I didn't browse through them, feeling my penance is done.

Thanks for all of that.
You need not punish yourself your joke was funny...honest.
Alex

[xelasnave]

Here are some shots not good but all I have at the moment.
Alex

[sharpiel]

You're both philosopher and inventor. Da Vinci-esque!

[xelasnave]

Hi Les how are you.
Still doing the good work?
Alex

[raymo]

After perusing your pics it seems to me that the motors could fairly easily
be mounted directly above their respective wheels so that the chains
are vertical and very short, therefore much less likely to jump off their sprockets.
If the wheels' tyres were rubber, the motors could even run directly on
the tyres like they did 50 yrs ago on motor assisted push bikes.
raymo

[Steffen]

I thought this was a Frank Zappa thread...

[xelasnave]

Hi Raymo
Thank you for your input.
You are correct about the chain length but if I mount the motors above on the frame the thing wont fold up so I have to place them on the platform which can fold down and around as a total unit. Being on the platform the motors have to be where they are to provide room to stand.
I did try a direct to wheel drive which seemed promising even with the plastic tyres but again they would have been in the way of standing room.
I will persist with these motors but it is apparent that hub motors would be best.
Redoing the primary will fix it which it looks that must be done.
Its a pity as there was a lot of work went into them.
They are laid up with wire wound to hold the sprockets (which caused the mold to distort).
They are so strong the only way I can dismantle them is to burn the fibre glass and resin or just buy new bits.
You can see why this project keeps my mine off other things.
Alex

[raymo]

Oh well, back to the drawing board; at least you're not getting bored.
raymo