the one thing that comes to mind at the moment is the person making this thing top heavy and when it would first crest floor and begin going down to the steps and tilting of the individual. that's a lot of weight and momentum to be able to just work within the confines of a regular wheel chair. So the track system will be engaged with the large wheels of wheelchair by way for chain and sprocket. So as the user drives with the big wheels the tank tracks should move with them also. We are including a sort of bike gear system to chain and sprocket so the wheels can be easier to turn or harder to turn depending on the speed the user wants to go. i like the idea of the disabled person being able to power the tracked unit themselves by the chairs large wheels. i take it there has all ready been some thought on basic set of rails for the wheel chair to ride up upon to get into what ever this ends up looking like. as for the bike gear changing, i wouldn't want to know they put it into a faster speed because they wanted to rush that caused them to only tumble down the steps. i think one speed would be more ideal and less parts and hassles further down the road. i would think that a section in the rail should have a cut out where there should be 2 rubber friction wheels where the large wheel would sit. there would be something just below where this wheel would bottom out so the front wheels can rid right past and not get stuck. the 2 friction wheels could then be attached to a section of chain to drive the tracks. my next question then would be, can they only load themselves into this carriage from just one end or from both ends? how do you see them locking themselves into place without any real effort but still be solidly attached so they don't break free once the begin to tilt forward to go down the steps? and then getting back out of this carriage once they are safe? The tracks will be inside the wheelchair frame. Which is roughly 23 inches from the back of the wheelchair to the front. Then 17 inches from large wheel to large wheel. We were hoping to use sprockets of 2-3 inch diameter as we have only 18 inches from bottom of seat to floor with a crossbar being in the middle.
having the tracks just inside of the mounting rail is the most practical way to go. i don't think anything much wider than 2" should be needed. as for your sprocket sizes, i would have the ground speed of the tracks the same speed as large wheel on the chair, this way the person don't need to remember it goes faster or slower than what they are normally accustom to - no additional sudden surprises during a time of emergency. what you might also what to think about is when they enter the rail, have the front wheels raise up a bit when they are finally locked in place, maybe 1.5" this way they don't feel completely off balance when traveling down a hallway and can still see things as well as can be expected, but it will help with the center of gravity for when they come down the steps, help with them going over the first step (not a lot, but better than nothing) and will help with the feeling of falling forward just a bit while going down the steps (again, not sure how much as i don't have any kind of working model myself to work with) chris In a message dated 4/22/2014 10:45:12 P.M. Eastern Daylight Time, [email protected] writes: Actually Chris it will be a type of medical device to help a wheel chaired person go down the stairs in an emergency situation. We are using a track system to enable the user to do so. We are not actually building an RC tank. I am sorry if this forum is only for rc tanks, but I did legitimately have questions on how you guys go about choosing your type of track system. I am so glad to hear that you were able to deduce the purpose of our project from such a poor description. This means our even more detailed report would allow others to imagine a more vivid image of the project. Here is the low down on our project. We are building an attachment to a wheelchair to help the wheelchair population travel down stairs during emergency situations by themselves. All products today require the assistance of others during emergencies and we wanted to make wheelchair users more independent. So the track system will be engaged with the large wheels of wheelchair by way for chain and sprocket. So as the user drives with the big wheels the tank tracks should move with them also. We are including a sort of bike gear system to chain and sprocket so the wheels can be easier to turn or harder to turn depending on the speed the user wants to go. But we had limited the max speed to 5mph for safety reasons. Our wheelchair does not need to go up the stairs yet, we want to deal with going down first. Maybe after securing that function we can incorporate a motor to help user go up also. A normal wheelchair has max weight of 250lbs and wheelchair has a weight of approximately 50lbs with the footrests. So in turn the tracks will need to hold about 300lbs. If we are able to build a working project. I would gladly share the images and designs with you. In addition also mention you as an advisor in our presentation. The reason we wanted tracks is because we desired as much possible surface area with the ground as possible during descent in order to stop slipping or tipping over of user. The best way my group believed for this to happen was a track system. I am in charge of finding a suitable track system for our project. I came across your website and was hoping to get some tips and opinions on the type of track we should use. We planned on using the ones made by the rc robot war websites, but found out they were too expensive and pushed us to find a more cost-effective solution. The tracks will be inside the wheelchair frame. Which is roughly 23 inches from the back of the wheelchair to the front. Then 17 inches from large wheel to large wheel. We were hoping to use sprockets of 2-3 inch diameter as we have only 18 inches from bottom of seat to floor with a crossbar being in the middle. On Monday, April 21, 2014 2:21:27 PM UTC-7, [email protected] wrote: just thought of something else, i take it you all ready have some sort of hull in mind or designed for this vehicle. it might ideal to find a piece of cardboard, draw out the hull (at least maybe the first foot of it), do some cut outs of road wheels and idler/sprocket wheel and tack them to it. then if possible, take a piece of string/twine/rope and run it around the those few wheels, then take it to the bottom of the steps and see how it's going to make contact. this might explain what i was just thinking in that last email as to how your vehicle's tracks will make contact and possible give rather than trying to start climbing and possibly avert any problems in the design later. chris -- -- You are currently subscribed to the "R/C Tank Combat" group. 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