Land vehicles – Wheeled – Occupant propelled type
Patent
1992-09-30
1994-03-29
Hill, Mitchell J.
Land vehicles
Wheeled
Occupant propelled type
280233, 280234, 280240, 2802421, A61G 502, B62M 112, B62M 114
Patent
active
052978109
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to transport facilities and, more particularly, to wheelchairs for invalids.
PRIOR ART
Known in the prior art is a transport vehicle comprised of a frame with a seat, installed on driven wheels and on one driving wheel having a yoke secured in the frame bearing, a hand lever installed on the frame with provision for swinging and provided with a turning handle connected by shafts and bevel gears with the driving wheel yoke. The vehicle has also a transmission mechanism which converts the swinging motion of the lever into the rotary movement of the driving wheel, and an overrunning clutch mounted on the driving wheel axle.
The transmission mechanism has the form of a block installed on the driving wheel axle and connected by the overrunning clutch with the driving wheel at one side and by a flexible tie with the frame post at the other (SU, A, 1138156).
The known transport vehicle only has low maneuverability since it cannot move sideways. The limited nature of its motion is due to the fact that the driven wheels are rigidly secured to the frame and, consequently, cannot turn around their vertical axis. When the driving wheel turns sidewise, the vehicle only turns around one of its driven wheels but fails to move sidewise. Besides, the provision of only one driving wheel is unable to impart side motion to the vehicle due to an insufficient adhesion of the wheel and the ground.
SUMMARY OF THE INVENTION
The main object of the invention lies in providing a wheelchair for invalids which would includes such additional elements which add to its maneuverability.
This object is attained by providing transport means for invalids comprising a frame with a seat installed on driven and driving wheels with the driving wheel yoke secured in the frame bearing, a band lever installed on the frame with provision for swinging and having a turning handle connected to the driving wheel yoke via shafts and bevel gears, a transmission mechanism which converts the swinging motion of the lever into the rotary motion of the driving wheel, and an overrunning clutch mounted on the driving wheel axle wherein, according to the invention, there is a second driving wheel and a second hand lever with a turning handle connected by shafts and bevel gears with the yoke of the second driving wheel, the transmission mechanism of each driving wheel comprising a guide formed in the yoke of its driving wheel and accommodating a rod with a rack, passing through the frame bearing, a gear mounted on the driving wheel axle and interacting with the rack and with the overrunning clutch of its driving wheel, and a coupling connecting one of the shafts with the rod while the driven wheel is self-aligning.
This arrangement ensures a high maneuverability of the wheelchair because when both driving wheels are turned to the side, the wheelchair moves sideways and the self-aligning driven wheel does not create a point of turning. If the driving wheels are set out of parallel, the point of rotation of the wheelchair is determined by the intersection of the driving wheel axles.
It is reasonable that the rod of each transmission mechanism should be provided with an additional rack located on the side of the driving wheel axle opposite the first rack and interacting with its driving wheel via the additional gear and overrunning clutch.
Such a layout rules out the free travel of the hand levers because the racks transmit rotation to the driving wheel in turns. On the upward stroke of the rod, the rotary motion is transmitted by one rack while the other rack moves idly due to the free travel of the overrunning clutch. On the downward stroke of the rod the rotary movement is transmitted by the other rack while the first one moves idly due to the free travel of the other overrunning clutch.
To promote reliability of design, the coupling in each transmission mechanism, connecting the rod with the shaft has the form of a cardan joint and that each hand lever should be secured to the frame by a hinged joint.
This arrang
REFERENCES:
patent: 645144 (1900-03-01), Tolson
patent: 689303 (1901-12-01), Hall
patent: 4560181 (1985-12-01), Herron
patent: 4762332 (1988-08-01), Seol
patent: 4798395 (1989-01-01), Shaffer et al.
patent: 4865344 (1989-09-01), Romero, Sr. et al.
Hill Mitchell J.
Mezhdunarodny Fond Miloserdia I Zdorovya
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