Yes, sir, we'd be happy to let you take a test ride in our new 3-speed wheelchair. Just slide into it, while I tell you a little about it.
The multi-speed drive is based on a pair of planetary gear hubs, one for each wheel. They aren't any new-fangled technology, it's the same thing used on three-speed bikes forty years ago. And pretty robust, too. Yes, one for each wheel, but they shift together from a single control.
Now, you notice the main difference between this chair and your old one is these two bars, one coming up from just inside each wheel, with handgrips at the top. This is what you use to power and steer your chair, rather than grabbing the wheels directly. That in itself is an advantage when it's cold, wet, muddy, slushy, or if you just run over something you'd rather not deal with.
Where these attach, down by the wheel, is another piece of not-new technology you're doubtless familiar with: it's a reversible ratchet, no different from what you might find in a wrench. The ratchet is based on ball rollers, so it's silent; I don't know if you're familiar with that exact type, but they've been around a long time.
Place your hands on the handgrips. You will be able to move the wheelchair by pushing, or in reverse, pulling, on the bars. But before you take off, let me continue with some important points.
You will notice that the bars have a wrist joint here just below the handgrips. In the normal operating mode, the handgrips are canted inward at about a 45 degree angle. If you snap the handgrip down to a ninety degree angle, that wheel will be locked to a driveshaft going through the axle tube. If you lock them both, you will be able to propel the chair in a straight line with just one hand.
Or, if you snap the handgrip up to a vertical position, you reverse the ratchet for that side. Therefore, you can still rotate this chair inside its own length by backing one wheel and going forward with the other. Put both grips up for moving in reverse. Please note that a small centrifugal device at the shaft connection prevents moving the ratchet into or out of reverse while moving at a faster pace than about a brisk walk, although this is adjustable to your preferences.
Oh, yes, the shifting mechanism. Twist the right handgrip, just like on a bicycle. The handbrakes work in bicycle fashion, as well.
Speaking of "bicycle fashion" - you had mentioned hearing of other 3-speed or multi-speed wheelchairs. Well, we have some of them, too: they look like a whole bunch of bicycle parts, all in the wrong places. Don't get me wrong, they are excellent machines, and fast. But for outside use, really; they are much longer, and can't be turned around in less than a fifteen foot circle. You could get to the grocery store much more quickly, but you'd likely be awfully frustrated inside. And loading them into a car? Twice the length of a standard wheelchair, half again the weight... you won't do it alone, I assure you.
OK, you appear to be set. Test the brakes a bit? Alright, try her out!-- lurch, Jul 01 2003 (?) Bloom County and Star Trek http://www.geocitie...est/2175/handi1.jpgOne strip... [RayfordSteele, Oct 04 2004, last modified Oct 05 2004] (?) Cutter John & Friends http://www.bloomcou...m/opusnfriends.htmlImage 3 on this page. [DrCurry, Oct 04 2004, last modified Oct 21 2004] (?) My personal all-time favorite Bloom County strip http://www.bloomcou...com/fav_strip4.html [DrCurry, Oct 04 2004, last modified Oct 21 2004] (?) 2 speed wheelchair http://fac-staff.se...usins/twospeed.htmlA 2 speed chair from 8 years ago, one of many similar research projects [English_gent, Oct 04 2004, last modified Oct 21 2004] lever-operated wheelchair http://www.csuchico...heelchairWins.shtml [BJS, Apr 22 2007] (?) Retrofittable Rowing Wheelchair http://lemelson.ham...e.edu/Projects.html [BJS, Apr 22 2007] The Rowchair http://web.mit.edu/...chair/rowchair.html [BJS, Apr 22 2007] Hub gear http://en.wikipedia.org/wiki/Hub_gears [BJS, Apr 22 2007] Good thing the end user already needs a wheelchair!-- snarfyguy, Jul 01 2003 Allow me to add your first croissant. (+)-- FloridaManatee, Jul 01 2003 As long as you can keep the weight down ...-- FloridaManatee, Jul 01 2003 As used, I imagine, by Cutter John and the rest of the Bloom County gang to play Star Trek.-- DrCurry, Jul 01 2003 [DrC] - would you mind explaining that?-- lurch, Jul 01 2003 That's twice today I've been involved in a discussion concerning Bloom County.
Lurch, you might remember it as 'Outland,' to which the name was changed. One of the main cartoon stars was a wheelchair-bound guy with a wild imagination.
Just the idea of having a planetary gear system in the wheels is good enough to get a + from me, although I think I'd eliminate the handlebars, ratchet, and such and just stick with a handwheel connected through the gearing to the tires.-- RayfordSteele, Jul 01 2003 Since each wheel has its own set of gears, there's the possibility that the wheels might not be in the same gear...-- phoenix, Jul 02 2003 random, halfbakery