If the suspension elements don't wear perfectly evenly or are not perfectly evenly charged to begin with, it will be like riding on an out-of-round wheel. That is, instead of absorbing bumps, the suspension will feel like you are riding over regularly spaced lumps. It will be fiddly to maintain.
You also use one third of the suspension at a time. Trading what the suspension spokes weigh versus a suspension with a single spring and shock per wheel, is also probably going to be a favorable trade-off.
Some quick Googling shows there are existing suspension wheelchairs that look like they use mountain bike rear suspensionspring/shock components, and it looks like there is sufficient room under the seat to accommodate a suspension.
You also use one third of the suspension at a time. Trading what the suspension spokes weigh versus a suspension with a single spring and shock per wheel, is also probably going to be a favorable trade-off.
Some quick Googling shows there are existing suspension wheelchairs that look like they use mountain bike rear suspensionspring/shock components, and it looks like there is sufficient room under the seat to accommodate a suspension.