1. Field of the Invention
The present invention relates to a wheelchair which may be propelled by the individual seated in the chair and particularly relates to a wheelchair having a pair of pivoted levers along opposite sides of the chair movable by the seated individual to provide a power stroke to the wheels to propel the wheelchair in a forward direction.
2. Discussion of Prior Art
As well known, a conventional wheelchair has a pair of large rear wheels on its opposite sides and smaller casterable wheels adjacent the footrest at the front of the wheelchair. Typically, the wheelchair is propelled by the individual seated in the chair using push rims, i.e., circular rims generally concentric with, but projecting outwardly from, the large wheels. The individual grasps the push rims and rotates the wheels in either direction to propel the wheelchair in either forward or reverse directions or differentially to turn the wheelchair. That is, by rotating one wheel faster than the other, or maintaining one wheel stationary while rotating the other, directional movement may be obtained.
Many and various proposals have been made to facilitate the propulsion of a wheelchair by a pumping or rowing action by the individual seated in the chair. Bicycle-type drive mechanisms, for example, have been proposed, as well as a large variety of other mechanisms to gain the mechanical advantages afforded by these mechanisms. However, many such mechanisms suffer from the disadvantages of complexity and expense and have not, to applicant's knowledge, been adopted in commercial applications.
An example of the above is U.S. Pat. No. 4,453,729, issued June 12, 1984, which discloses a wheelchair employing a pair of levers at opposite sides of the chair which engage and disengage cables about a clutching mechanism associated with the wheels. The drive mechanism employs a sleeve swaged onto the cable to engage a drive disc, as well as a ratchet and pawl arrangement to permit free wheeling in both directions and rearward movement of the wheelchair. This type of arrangement, however, is quite complicated, expensive to manufacture, and does not afford a variable speed mechanism.
Other proposals have employed levers interconnected to ratchet mechanisms connected to the wheels by means of rods. In one such system, the speed of the wheelchair may be varied by repositioning the rods at different points of connections with the levers. This is exemplified in U.S. Pat. No. 4,762,332 to Seol. See also U.S. Pat. Nos. 3,994,509; 4,811,964 and 4,727,965 for additional types of manual driving mechanisms for wheelchairs.