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US 4,538,825 AGranted
Wheelchair anti-rollback mechanism
AssigneeGeorgia Tech Research Institute
InventorsRonald D. Delahoussaye, James W. Brazell, II
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AssigneeGeorgia Tech Research Institute
InventorsRonald D. Delahoussaye, James W. Brazell, II
Estimating the term…
The customary side hand propulsion ring adjacent to each main wheel of a manual wheelchair is mounted through a lost motion connection between the propulsion ring and main wheel so that the propulsion ring can have limited rotational movement relative to the main wheel. A friction brake drum or partial drum fixed to the wheelchair frame inside of the main wheel is engaged by at least one of a plurality of circumferentially spaced over center friction locking devices pivotally held on the main wheel. Each over center friction locking device is moved by a release element to a non-locking position relative to the drum or partial drum in response to reverse movement of the propulsion ring by a chair occupant. Economy and ease of operation are provided for. The wheelchair occupant need not remove his or her hand from the propulsion ring when operating the anti-rollback mechanism.
In a wheelchair, a main chair wheel, a manual propulsion ring disposed adjacent to said wheel, means forming a lost motion connection between the propulsion ring and said wheel, a relatively stationary drum element fixed on said chair near said wheel, at least one pivoted over center cooperative braking device attached to the wheel and turning therewith and passing freely across the surface of the drum element during forward propulsion of the chair and automatically assuming an anti-rollback positive locking position with the drum element when the chair tends to roll back on an incline, and connecting means between the means forming a lost motion connection and the pivoted over center braking device and being operable to move the braking device out of engagement with the surface of the drum element during conscious backward propulsion of the wheelchair by its occupant.
An anti-rollback mechanism for a manually propelled wheelchair having a pair of main wheels and a pair of manual propulsion rings near the outer sides of the main wheels, lost motion means connected between at least one manual propulsion ring and the adjacent main wheel of the wheelchair, a relatively stationary brake drum element fixed to the chair near the interior side of said main wheel radially inwardly of the periphery of the main wheel and manual propulsion ring and being in concentrically spaced relationship to said periphery, at least one pivoted over dead center braking device attached to the main wheel near its periphery and radially outwardly of the brake drum element and automatically engaging the brake drum element in a locking mode to resist backward rolling of the wheelchair on an incline while allowing free forward manual propulsion of the wheelchair through said manual propulsion rings, and means connected between said lost motion means and said pivoted over dead center braking device to release the latter from engagement with the brake drum element during conscious rearward propulsion of the wheelchair through said manual propulsion rings.
Dependencies are inferred from the claim text.