All terrain handicapped scooter is in the conception stage. Four wheels, maybe 4x4, electric, knobby tires, possibly articulated steering, normal walking speed. Main use is around a small farm but "scooter" looking enough to be allowed at farm, auto and air shows. Some places charge $85 a day for rentals. Most shows won't let him use his golf cart.
What horsepower/watt 12v motor do I need? Controller? Gross weight, maybe 400/500#. I'm thinking light weight lawn mower transaxles.
Andy, I have a scoot that has been around for years. It has gone thru many different drive techniques over the last 5 years. I posted photos of it in the dropbox back in 2000 under the header of "scootr".
The text over there says manufacture unknown, however, about 3 years back, I found another one at a swap meet. This one was in tougher shape, but had a tag on it: JET Personal Transporter - made in Michigan. It had hard rubber tires originally, I added the air tires. The front handle bar uncoupldes by the neck and makes it real nice to lift into the trunk. I love the thing as long as I can keep it running... The kids in the neighborhood love it, and well, often it gets abused.
Whats great about this thing is the "stand-on" aspect. Just step aboard and take off. It certainly could be fitted with a seat post. The 3 wheel nature makes it always stay in contact with the ground. With 4 wheels, you can get tottering and loss of traction.
Originally, this one had a single front motor and went at a fast walk. To pep things up a bit, the last thing I had on it was a pair of 12v pancake motors, one on each side of the front tire. Two garden tractor deep cycle batteries and a controller off of ebay made the thing run
15mph for about 6 miles. The kids sure loved it, but it didn't take long and they killed the batteries dead by running it totally dead.
The other one I have I put a native to handicap cart rear axle on. It runs at a medium walk and runs for a long time on one battery because the motor is geared down quite a bit. While it spins a lot, there is not much load unless doing hills. The front wheel drive one is far more fun though, not because of speed (though the burnouts are fun -went thru a few front tires already) , but rather how it pulls around a corner. Turns on a dime because there is no differential to fight the turn.
Eventually, one will have a gas motor on a front drive wheel for fun, and the other will be electric and go a medium walk speed as it was intended.
I cant help with the hours of math involved to do it right.... I just open a draw and see what spare motors might be around and use what i have.
might give you some ideas. The Extreme 4X4 is pretty impressive. I've used a demo in 12" of snow and it didn't even slow down. Range is affected by having four motor/gearboxes, but with 75 Amp-hour Group 24 gel batteries, the range is acceptable for all but the most active user.
There's also the TracAbout,
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which runs on smooth treads. I've run one of these too. It had no trouble at all climbing over one of the 4' snow piles the plow guy left. It acted just like a dozer, crawl up until it broke over center, flip to the down side and crawl down. There might be some ideas there too.
They used to have small cleats on the treads, but they tended to absolutely destroy any tiled or carpeted surface. They found the smooth treads have more than adequate traction. I think they're right on that score.
I'm trying to figure out a wheelchair power supply using a small gasoline or propane engine-driven generator. A user could run on the motor-generator outdoors and battery power indoors. I'd like to have excess power charge the batteries while on engine power. The idea is to emulate a motor generator locomotive, but with battery power option.
The power requirement would be appx. 70-100 amps @ 24 volts or 1700-2400 watts. At 746 watts/hp, I'd need about 3-4 hp, allowing for losses, no? Then there's finding a 24 V DC generator that size.
Most of the time the current draw would be much lower than 70 amps.
Why not size your motor for the average draw? That would allow you to have a much smaller motor, and better fuel efficiency. During acceleration and hill climbing, you would rely on some stored energy from your batteries, but going down hill, and while stopped, you would recharge. I think you'll find that the average user sits at a stop for large periods of time.
Sounds interesting. Let me know if you need any help.
By the way, there's a Rex Winfrey on the Practical Machinist board, who lives out your way (Cleburne area) and is a very good machinist, works in an independent shop doing Bell Helicopter stuff. He's also an inventor who has developed an amazing prosthetic hand. Might be a good guy to talk to.
I just want to be sure to have the most reliability for size, weight, price, etc. What you suggest might well be the best combination. True, the generator need not supply the maximum possible current draw all the time it's operating, just enough to offset what charge is used in indoor operation and supplement in high load periods.
I wish I sat at a stop most of the time. On my job, I'm on the move 4-6 hours per shift. I end up charging my batteries about every night. The generator would be about useless to me since I'm indoors most of the time except to and from work.
Since I can still walk enough to get from my van to the building and home, my chair stays at work most of the time.
I would recommend that the motor and drive controller be 24 volt. A permanent magnet PM motor would probably provide the best performance, and operate as a generator when coasting (with some additional circuitry).
Curtis has some very versatile and compact 24V controllers for bicycle and scooter applications. Charging two 12V batteries wouldn't be complicated, or locating a 24V maintenance charger shouldn't be difficult.
Drive train components can be obtained from surplus dealers, and SED has a lot of new stuff to choose from
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All Terrain might be what you have in mind, but Indoor - Outdoor may be a closer term for the concept you want to achieve. The AT design sort of implies the ability to handle a lot of risky challenges, for even a non-handicapped operator.. big tires, shocks and springs for hard landings, all-wheel drive and other extreme design considerations.
He's diabetic with leg circulation problems. He has a nice power chair for indoors. Just wants something for a little more go-anywhere capability. He regularly sticks the golf cart. Most places he would visit don't allow gas engines.
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