Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
2000-03-21
2001-05-22
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Occupant propelled type
C280S304100, C280SDIG001, C297SDIG004
Reexamination Certificate
active
06234504
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a user-propelled vehicle or wheelchair. More particularly, it relates to a wheelchair propelled by push levers connected to drive wheels through bicycle chains and variable ratio rear gear clusters.
2. Description of the Prior Art
Most wheelchair users have little or no functional use of their lower extremities, but have preserved normal upper body function. Accordingly, the conventional wheelchair requires the user to propel the chair by repetitively pushing on push-rims attached to the main wheels of the chair. The arm and shoulder motions that are required are undesirable because they utilize the small, relatively weak, muscles of the rotator cuff and ultimately lead to stress injury and degenerative arthritis of the shoulder joint. This is also an inefficient means of locomotion; providing only a one-to-one ratio of distance traveled for distanced pushed. It is, however, an ubiquitous and relatively simple machine that can be easily maintained. Several attempts have been made to improve on this standard with very limited success.
Several inventions employ the use of levers for the user to propel the chair. This is an improvement because it makes use of the larger and more powerful triceps and pectoral muscles, with reduced shoulder stress. Still, however, all of these devices have fallen short of success.
For example, U.S. Pat. No. 4,865,344 provides only one speed having one fixed gear ratio, and thereby forgoes the significant mechanical advantage gained by using a set of multiple gear ratios This machine also requires the user to steer with hand levers attached to the push levers, increasing the complexity of steering and propulsion movements.
U.S. Pat. No. 5,322,312 is another attempt to propel a wheelchair with a push lever. It also lacks sufficient mechanical advantage, having only one gear ratio. The use of a detachable skateboard device makes this machine unnecessarily complex, expensive, and difficult to maintain.
U.S. Pat. 5,209,506 is cumbersome in requiring the user to steer with handlebars which are simultaneously pushed and pulled to propel the chair. The linkage required to operate this machine is also too complex for easy care, and the position of the steering/push lever obstructs easy entry and exit of the chair.
U.S. Pat. No. 4,811,964 also uses push levers for power, but in a rowing motion. This machine would be difficult to steer, having a combined row-steer motion; it also has only one speed, and uses a complex system of pulleys and linkage, all of which serve to make it impractical.
U.S. Pat. No. 3,994,509 is another lever-driven machine that makes use of a very complex and expensive system of forward and reverse clutches. It also provides only a single forward speed, and has a very wide profile, to accommodate the wide-set wheels.
There are several inventions that use a set of bicycle pedals to turn a crank which, in turn, transfers power via a bicycle chain to either front or rear wheels. All of these hand-crank designs suffer from the fact that the hand cranking motion is extremely fatiguing. Further, they are too big and too heavy. The cranking/steering device obstructs entry and exit. These wheelchairs generally lack multiple gears and are difficult to steer while cranking. U.S. Pat. No. 4,720,117 is a typical example of this type of machine.
U.S. Pat. No. 5,362,081 is an attempt to adapt the mechanical advantage of multiple gear ratios to the standard wheelchair format. It does not, however, save the user from the repetitive motion injury and degenerative damage to the shoulder joints; and, in requiring the use of the user's smaller, weaker rotator cuff muscles, it is more fatiguing than a push lever driven machine. This particular model also requires the user to let go of the steering/drive wheel to shift gears.
OBJECTIVE OF THE INVENTION
It is the object of this invention to provide for, in a wheelchair of simple construction, an alternative means for manually powering the wheelchair which utilizes the strong shoulder and arm muscles of the wheelchair occupant while providing for a selection of gear options to drive the wheelchair in a forward or reverse motion.
SUMMARY OF THE INVENTION
Applicant provides for a wheelchair propulsion apparatus that improves a user's ability to propel a chair with less effort and greater speed over a longer duration. Compared to present wheelchair options, mechanics used in Applicant's wheelchair decrease the stress on shoulder joints and diminish the degenerative joint disease often accompanying prolonged wheelchair use.
Applicant's wheelchair is propelled through use of two push levers, which the user pushes forward utilizing triceps and pectoralis muscles. Ratchets attached to these levers allow the user to retract the levers to the start position with little resistance.
Power is transmitted from the push levers to drive sprockets through bicycle chains to the multi-speed rear wheels. Multiple gear ratios are made possible by shifting the drive chain to different size rear wheel sprockets with a derailer mechanism.
Turning is accomplished in the same manner that it is done with a standard wheelchair. One wheel is pushed more than the other, or a braking force is applied to one wheel while the other is pushed. Braking is accomplished effectively by using calliper brakes similar to those used on a typical bicycle.
This apparatus provides for a most efficient means of wheelchair propulsion, with significant physiological benefits to the user.
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Lum L.
Swann J. J.
Walkers LLP Jackson
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