Midwheel drive chair ??

[sacharlie]

Limitation or benefit of a single rear caster over the usual two.
Likewise with the front casters.
The above can be viewed with the large under seat space required by the old bulky lead batteries or the freedom of design when building a Li battery.

Any thoughts?

[sacharlie]

Ah, the single front caster would interfere with an ezlock.

[ex-Gooserider]

In theory at least, there could be stability issues as there would be a lack of support on the corners - so that the chair could tip on a line between the caster and the drive wheel.... I'd see this as a major concern on the front end especially.

Motorcycle 'trikes' are noted for stability issues when turning at speed as the outside rear wheel will try to come up and flip over the diagonal between the front wheel and the inside wheel.... (It is one reason why the off-road 3 wheelers were replaced by 4 wheelers - to many wrecks got the gov't regulators upset....)

Back in my sidecar days it was easy to 'fly' the chair by turning towards it (for a US style RH mount rig, a right turn), the chair would lift up over the bike wheels... Left turns could be taken much faster as the chair wheel would hold the bike vertical, but if one was going fast enough the bike would lift the rear wheel around the line between the front wheel and the sidecar wheel. This was MUCH more dangerous as it happened very fast, and plunged the nose of the sidecar into the pavement - giving a very high risk of flipping the works....

OTOH I believe some of the powerchair soccer folks have been known to replace the usual rear anti-tips with a much stouter central rear caster, which was enough to keep from going over backwards but didn't have the same stability concerns as most folks don't go that fast in reverse....

ex-Gooserider

[sacharlie]

In theory at least, there could be stability issues as there would be a lack of support on the corners - so that the chair could tip on a line between the caster and the drive wheel.... I'd see this as a major concern on the front end especially.

...

OTOH I believe some of the powerchair soccer folks have been known to replace the usual rear anti-tips with a much stouter central rear caster, which was enough to keep from going over backwards but didn't have the same stability concerns as most folks don't go that fast in reverse....

ex-Gooserider

OK yes I can see that. So the single center FRONT caster is out.
As for a single center rear caster. The single rear caster can be seen as a narrower delta configuration then with the dual rear casters. A flip over potential would be greater if taking a slop at a 45° angle.
Thanks

[ex-Gooserider]

In theory at least, there could be stability issues as there would be a lack of support on the corners - so that the chair could tip on a line between the caster and the drive wheel.... I'd see this as a major concern on the front end especially.

...

OTOH I believe some of the powerchair soccer folks have been known to replace the usual rear anti-tips with a much stouter central rear caster, which was enough to keep from going over backwards but didn't have the same stability concerns as most folks don't go that fast in reverse....

ex-Gooserider

OK yes I can see that. So the single center FRONT caster is out.
As for a single center rear caster. The single rear caster can be seen as a narrower delta configuration then with the dual rear casters. A flip over potential would be greater if taking a slop at a 45° angle.
Thanks

That is quite correct, but as I said, power soccer chairs, not 'daily drivers'.... Since a soccer chair is just going to be used on a flat floor, slopes aren't a concern... OTOH they may be accelerating as hard as the rules allow, and have to keep the front end down, so they will set up stout anti-tips and have them close to contact with the floor.

ex-Gooserider