Beach Chair

Unsoundcode

I want to build a wheelchair that can travel across sand. I am looking for advice and links. What I am thinking is that the tires need to be wide and independantly driven or a drive train right and left. I visualize the steering being accomplished by adusting speed ratio of opposite sides the turning circle does not have to be too tight.

Initially I would like to be able to transport a 200 pound load for at least an·30 minutes·over a reasonably level sand terrain. I can manufacture a lightweight frame but would like help choosing tires , motors, the best way to gear motor to drive shaft and suggestions on what kind of battery pack I would need. I am wanting the motors to fall within the control of HB25's.

Apart from selecting components gearing is a weakness for me and calculation of motor size and power requirement. Overall weight will be a factor.

I welcome all suggestions

Jeff T

Phil Pilgrim (PhiPi)

There are so-called "sand tires" made for mountain bikes that might work for you.

-Phil

Unsoundcode

Thank you Phil, tires are going to be an expense item I know. There are conversion kits for non motorized wheelchairs where the tires can be anywhere from $800 to $1500 a set of 4 with axles. Some popular commercial models of chair are constructed with PVC tubing. I am planning aluminum tubular or box section frame where the passenger will sit low with legs straight, kind of like a go cart. Considering you can buy a ready built motorized "sand chair" for $8000 and up I hope to get below half of that cost. The kit tires ·I have looked at are approximately 10 to 18 inches in diameter and a width of about 8 or 9 inch, they include a hub here's one link I found

http://www.hotshotproducts.org/product.htm

I am hoping to find a cheaper alternative but in the end will go with what is best.

Jeff T.

Phil Pilgrim (PhiPi)

Oh, I see what kind of tires you mean now. Those are way different from mountain bike tires!

-Phil

Franklin

Google go-kart

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- Stephen

Lawson

anywho, ATVs and small trailers have wheels and tires similar to what you're looking for. www.surpluscenter.com/ www.northerntool.com/ Are two places to look for stuff like this.

On sand all wheel drive is a good idea. Windshield wiper and or power window motors chain driving the wheels is a good place to start.

best of luck
marty

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Lunch cures all problems! have you had lunch?

Unsoundcode

Thanks Stephen , Marty. ATV or go-cart wheels might be a good option, I intend to make a trip to Northern tools and TSC I believe they sell the axle kits too. I am wondering on their weight.

Would windshield motors carry the load, I must admit I was thinking about windshield motors at one point. If so what would be the best battery configuration. I wondered if I might need a deep cycle marine battery or if a regular car battery would do.

Jeff T.

Mr. Richard

here is a link for some wheels that might fit your needs

http://www.wheeleez.com/index.php

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Magic Smoke Theory of Electronics –
Inside every electronic part there is magic smoke.
The magic smoke is what makes everything work.
If you release the magic smoke, the part stops working!

kelvin james

If you want to look at the physics of propelling a vehicle through sand, there is a need for a great amount of torque and power, which is going to cause a major problem going with only battery power. The idea is to displace the weight over the biggest area possible, with some big balloon tires with all wheel drive, or even better, some tracks. The gas/ hybrid would be the way to go for this. I think you could still achieve the projected cost of development with the hybrid.

stamptrol

Hi Jeff,

Have a look at the TETRA Society website. A while ago, one of the chapters built a beach wheelchair to get folks across the sand and into the water. The tires were plastic, I believe and quite wide, but light. I'll see if I can get the link and will edit this message.
· EDIT:·· Can't find the pic of the TETRA beach chair but I did find this: http://www.beachwheelchair.com/


Tom Sisk

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Tom Sisk

http://www.siskconsult.com


Post Edited (stamptrol) : 10/13/2007 3:09:36 PM GMT

Unsoundcode

Hi all thanks for the input.

Hi Kelvin, the physics of this project do concern me and is something I am going to get ironed out before I make too much investment. I have seen electrically powered beach chairs on various web sites so I think electric power is doable. I am not good with gas engines and the thought scares the hell out of me whereas I feel comfortable with the electric option. My initial aim is 2-6 mph for 30 minutes with something like an 16-18in wheel.

I believe the wheels in the link from Mr Richard will ultimately be my best bet. They are low pressure (2-4 PSI) balloon tires designed to travel across sandy terrain with the least amount of effort. The balloon tires weigh approximately 5lbs each as opposed to ATV tires and rims which weigh in at an average of 20lbs each from what I have seen.·I have a couple of questions for Wheelez which I will email today and possibly place an order.

Motor selection is still on my mind and I am debating between a 12v or 24v system, I would like to use the HB25s for control if I can drive the chair with motors that fall within their specification. I have an outline of the frame sketched out which so far has four stub shafts individually driven by chain and sprocket. As things progress I may go to rear wheel drive with a steered front end. Right now I have a lot of flexibility.

Tom I would love to see the TETRA link if you come across it, I know you have modified vehicles before ,do you have any suggestions on motors.

Jeff T.

kelvin james

Looking around at some of the beach chair info, the carrier type mover would be a good idea. They just drive their wheelchair up a ramp onto the beach carrier and away they go. It would be enough trouble for a disabled person to get into one wheelchair, let alone getting into another one, getting out of that one, then back into their own.

Unsoundcode

Kelvin you are absolutely right in taking into consideration the disposition of the person who will eventually use the beach chair. The chair is for my wife so the end design is definitely out of my control ··

We have not ruled out the ramp and cart setup but feel the kart design would not be any more difficult to fabricate and will possibly give a little more freedom/independence and a better style. The suggestions are great and we look at everyone of them for ideas.

I wrote to Wheeleez with questions regarding axle and rim configuration, and unbelievably I may have a source for an old electric wheelchair I can salvage the motors from·at no cost.

thanks

Jeff T.

Todd U

·Here me now believe me later. Do not try to re-invent the wheel. What you want is already availible in what is known as a power chair.These machines use 24 volt dc motors that drive gear boxes designed to pull heavy loads·and are controlled by high amp (50+)·sophisticated electronics such as the Penny & Giles·VR1. Very expensive when purchased new but there are always used units·availible on Ebay.I bought a very nice one for $300 and have seen many other nice units in this price range. Problem is·you must do pick up only due to high shipping·weight. However,it is worth traveling 200 miles (in my case) to obtain such a powerful machine that you can convert into anything imaginable from mobile robotics to a modified beech mobile. So there you go, modify the hubs, frame,whatever and of course the big wide light weight wheels/tires- beef up the batteries and your off.

Todrik

Todd U

Hey Unsoundcode,

What say you ? You asked a question . You should reply to all respondents, last word - if you will.

Todrik

Unsoundcode

Hi Todd, sorry for the negligence. I heed what you say and here is a progress report.

I had an electric wheelchair given to me, so I have motors , rear motor controller and the start of my frame. I have bought some 15" lawnmower wheels with aluminum rims today and currently machining a hub to mate it to the wheelchair. Lack of Parallax hardware right now but I do have plans to add in some features where a BS2 and HB25 will come in handy.

Thanks again

Jeff T.

Unsoundcode

Over the last few weeks I have had time to do a little more work on the design of my beach chair. The motors have worked out well, maybe a tad under powered but seem to be coping, the battery motor combination will certainly be able to run longer than my original expectations.

The rear wheel hub turned out great and so did the castors, which I had reservations about.

I have yet to clean up the upholstery and fit stirrups for the feet,·the controller bracket also needs repair.

I designed an extension to the existing chair that folds back for transporting, still bulky but managable. The whole thing takes about 10 minutes to piece together.

I took it for a test run today, the best stretch of sand I could find in this area and a little firmer than I wanted but it did have a testing slope to it

Youtube video at this link http://www.youtube.com/kylia666

Jeff T.

stamptrol

Jeff,

Great looking project! Really jealous you don't have 6 feet of snow scattered everywhere.

Has your "Boss" had a chance to try it out yet?

Regards,

Tom

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Tom Sisk

http://www.siskconsult.com
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Unsoundcode

Hi Tom, my wife did ride in the chair in the yard at home before the long wheelbase extension which helped in some of the design decisions. To help keep her and make her feel secure the front end was raised two inches so that the seat tilted back which kept the body weight from being thrown forward, there is also a seat belt that fastens just above the waist. We felt the knee being bent at 45 deg with support at the feet would be the best for absorbing vibration. She is excited about it and it makes it a fun project. Allthough we had sun while doing the video the wind was extremely cold and her verve began to wane but all said she did a great camera job. The trial was done at Long Hunter State park close to Nashville TN and the backdrop is Percy Priest Lake.

Jeff T.

sam_sam_sam

Unsoundcode

You did a very good job on this Project looks very nice

······························ Youtube video

Looks real good and from what i see it seem to work real good

Thanks for sharing your Project



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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 2/11/2008 5:11:18 PM GMT

kelvin james

Where's the cup holder?

Excellent work. It is great to see ideas become reality.

Mike W

have you considered tracks

http://planetmobility.com/store/wheelchairs/power/tracabout/index.html