whburling

Hi,I am interested in modifying the wheel chair of a friend. He has been wheel chair bound since 15 and now is 63. He is still a kid, however, wheeling all over the parking lot in the early morning hours. Speed is one of his things. Rain or shine. His wheel chair is cheap as hell. I hate it. . But he loves it. Will not consider a new chair. So when the bearings failed for the second time of a chair 3 years old, I gave the design a good look. The basic design is that a bolt is cantilevered from a nut welded to the chair frame. The bearings are a very loose slip fit on the bolt. The bearings are more tightly fit into the plastic hub. The bolt head applies a force to the inner race of the outer bearing. That force is then supposed to pass through the inner race of the outer bearing through the hub to the inner race of the inner bearing to a collar welded to the chair frame. But I don’t think that happens. I think the bolt force passes through the inner race of the outer bearing through the balls through the outer race of the outer bearing through the hub to the outer race of the inner bearing through the balls to the inner race of the inner bearings to the chair collar. If that is true the bearings would be subject to shear which could be an explanation for the degraded bearings.The fix is to create a sleeve placed between the inner races of the two bearings so that the bolt force passes through the outer bearing inner race through the sleeve to the inner race of the inner bearing to the chair collar sized to press against the inner race only.To make it more simple, I designed an axle with the sleeve integral to the axle. I was quoted $50.00 an axle by the local machine shop. But then I realized that I was caught with a wheel whose manufacture is unknown. what happens when the wheel rubber wears too thin. So I began to consider adopting a bicycle wheel with a solid through axle. A 5/8” axle would work perfectly. It has a handle on it which looks like a quick release lever. But it is not. The lever is used to unscrew the axle from a threaded bolt just like in the wheel chair. So I am wondering if others have actually adapted their wheel chair design to use these axles. I will gladly listen to all experience. Secondly I need to attach some sort of rim used to propel the wheel chair. Does anyone have any ideas how to do that. If I use a road bike rim, there is little rim to attache the propelling ring. So I was thinking of attaching the ring to the spokes close to the rim. Any ideas are welcome.

Respectfully,

bil