Wheel chair abstract
A wheel chair propulsion device particularly for use by quadriplegics
that includes an annular ring smaller in diameter than the large
wheel of a conventional wheel chair and having a plurality of spaced
apart recesses in a surface thereof. The ring is fastened to the
wheel of the wheel chair in co-axial relation therewith and spaced
outward therefrom. A lever is pivotally mounted on the wheel chair
axle and an opposite end of the lever projects above the conventional
arm rest on the wheel chair. A drive mechanism is mounted on the
lever arm and positively engageable with the annular ring for rotating
the same and disengageable therefrom to allow free rotation of the
wheel. The drive mechanism comprises a lug movable into and out
of the recesses in the ring in response to movement of the lever
in a direction transverse to the plane of the wheel and resilient
compressible means which is compressed by movement of the lever
in a direction to move the lug into a recess in the ring.
Wheel chair claims
We claim:
1. A wheel chair propulsion device comprising:
(a) an annular ring, smaller in diameter than the large wheel of
a conventional wheel chair and having a plurality of spaced apart
recesses in a surface thereof;
(b) means for fastening said ring to the large wheel of the wheel
chair in co-axial relation therewith and spaced outboard therefrom;
(c) lever means having one end thereof adapted for pivotal mounting
on an axle mounting the large wheel on the wheel chair and an opposite
end that projects above a conventional arm rest on the wheel chair;
and
(d) a drive mechanism mounted on said lever arm and positively
engageable with said annular ring for rotating the same and disengageable
therefrom to allow free rotation of the large wheel when the ring
is mounted on the wheel chair wheel, said drive mechanism comprising
a lug movable into and out the recesses in the ring in response
to movement of the lever means in a direction transverse to the
plane of the wheel and resilient compressible means compressed by
movement of the lever means in a direction to move the lug into
a recess in the ring.
2. A wheel chair propulsion device as defined in chaim 1 wherein
said recesses are located on one of the inner peripheral surface,
the outer peripheral surface and a side face of the ring.
3. A wheel chair propulsion device as defined in claim 1 wherein
said drive mechanism has a gap between which a portion of the annular
ring passes, wherein the lug projects into said gap from one side
thereof toward one side face of the annular ring and wherein a friction
braking material is located on an opposite side of the gap so as
to be engageable with an opposite side face of the annular ring.
4. A wheel chair propulsion device as defined in claim 1 wherein
said resilient compressible means is located on said drive mechanism
and engageable with a side face of said ring.
5. A wheel chair propulsion device as defined in claim 4 wherein
said compressible means comprises a sleeve slidably mounted on said
lug and spring biased in a direction toward a side face of the annular
ring.
Wheel chair description
This invention relates to improvements in occupant operated propulsion
systems for wheel chairs and wheel chairs incorporating the same.
Wheel chairs are generally driven by gripping hand wheels attached
to the supportive wheels and positioned laterally outward thereof.
Paraplegics having full control of arms and upper body muscles can
quite satisfactorily propel themselves by gripping the hand rims.
It provides excellent exercise as well as a convenient means of
propelling the chair to move from one location to another. Quadriplegics
on the other hand, may have some ability to move the upper part
of the body and the arms but not sufficient control to grip and
turn the hand wheels. While motorized wheel chairs can be operated
by quadriplegics there are a number of disadvantages associated
therewith. Apart from the obvious increase in cost of an electric
wheel chair, there are limitations on its use because of its weight
and size, the need for recharging and the increased maintenance
costs. Additional personal factors involved are the psychological
aspect of being dependent upon some motorized transport and a lack
of exercising.
There have been a number of devices proposed for use on wheel chairs
to facilitate occupant propulsion of the chair but in most instances
they are deemed undesirable structures and/or difficult to use by
quadriplegics. Obviously, any means used to overcome the problem
must allow for the possibility of forwards and backwards motion,
unimpeded transfer to and from the wheel chair, some kind of friction
braking to allow gradual descent down an incline and flexibility
to accommodate the various disabilities. As examples of various
known devices reference may be had to the following United States
Patents as well as generally to the prior art which may be found
in the U.S. Patent Office Classification Class 280, Subclass 242;
U.S. Pat. Nos. 3,623,748 issued Nov. 30, 1971 to Dewey O. Haynes;
3,869,146 issued Mar. 4, 1975 to Donald L. Bulmer; 3,877,725 issued
Apr. 15, 1975 to Herbert Barroza; 3,189,368 issued June 15, 1965
to James F. Petersen; 3,309,110 issued Mar. 14, 1967 to Donald L.
Bulmer.
In the foregoing prior art devices a lever arm is pivotally attached
to the axle of each wheel and associated with each lever arm is
a drive mechanism that cooperates with the wheel of the chair. The
drive mechanisms are of a wedge and friction type. The effectiveness
of such drive mechanism is dependent upon tire condition and generally
are considered unsatisfactory. Problems are encountered with such
type drive mechanisms when going up a ramp moving a heavy person.
Jamming also occurs and as the tires wear, which they do, they become
relatively inefficient. The movements and motions required of the
occupant to move the chair are not always in keeping with the capabilities
of quadriplegics nor the desired movements for proper exercise.
A principal object of the present invention is to provide an occupant
operated propulsion system employing a positive drive mechanism
that is simple to operate and provides appropriate movements and
motion for effective exercising.
In accordance with one aspect of the present invention there is
provided a wheel chair propulsion device comprising:
(a) an annular ring, smaller in diameter than the large wheel of
a conventional wheel chair and having a plurality of spaced apart
recesses in a surface thereof;
(b) means for fastening said ring to the large wheel of the wheel
chair in co-axial relation therewith and spaced outboard therefrom;
(c) lever means having one end thereof adapted for pivotal mounting
on an axle mounting the large wheel on the wheel chair and an opposite
end that projects above a conventional arm rest on the wheel chair;
(d) a drive mechanism mounted on said lever arm and positively
engageable with said annular ring for rotating the same and disengageable
therefrom to allow free rotation of the large wheel when the ring
is mounted on the wheel chair wheel, said drive mechanism comprising
a lug movable into and out of the recesses in the ring in response
to movement of the lever means in a direction transverse to the
plane of the wheel.
In accordance with a further aspect of the present invention there
is provided a wheel chair having a propulsion device as defined
in the foregoing paragraph on each of the large wheels thereof.
The invention is illustrated by way of example in the accompanying
drawings wherein:
FIG. 1 is an oblique view of a portion of a wheel chair incorporating
applicants' occupant operated propulsion mechanism;
FIG. 2 is a partial sectional view; and
FIG. 3 is an exploded view illustrating the components connecting
the wheel chair propelling arm to the axle of the wheel chair.
Referring to the drawings there is illustrated in FIG. 1 a portion
of a wheel chair and it is to be understood the other portion is
identical but a mirror image of that illustrated. The wheel chair
10 is a conventional type having a pair of large rear wheels 11
and a pair of front caster wheels 12.
In accordance with the present invention there is provided a hand
operable, propulsion mechanism 20 for each of the large pair of
wheels 11. Each propulsion mechanism 20 consists of a flat annular
ring 30 attached to and spaced from the wheel, a lever arm 40 pivotally
mounted at one end thereof on the axle 13 of the wheel and a positive
drive mechanism 50 mounted on the lever arm and cooperating with
the annular ring 30.
Referring now, particularly to each of the components, the rim
30 is a flat annular member having a plurality of preferably equally
spaced, apertures 31 therethrough or deep recesses therein. The
annular ring 30 (see FIG. 2) is mounted on the wheel by studs 32
threaded into lugs 33 secured to the rim of the wheel 11 and held
in appropriate, spaced relation from the wheel by spacers 34. As
an alternative to the lugs 33, bolts 32 may be anchored to the spokes
of the wheel by appropriate clips and/or clamps.
The wheel 11 is journalled for rotation on the axle 13 and such
axle is anchored to the frame of the wheel chair in a conventional
manner. The outer end of the axle has an extended threaded portion
14 on which the lever arm 40 is journalled for rotation and held
in position by a cap-nut 15 that threads onto the axle.
The lever arm 40 has first and second tubular portions 41 and 42
telescopically arranged with respect to one another for varying
the length thereof and positionable at various lengths by a pin
43. The pin 43 projects through one of a series of apertures in
the lever arm portion 41 and an aperture in lever arm portion 42.
The upper end of lever arm portion 41 is turned inwardly toward
the occupant of the chair providing a hand grip portion 44. At the
opposite end of lever arm 40, lever arm portion 42 is journalled
for rotation on the wheel axle extending portion 14 by an adaptor
45 having a bearing 46 in a flattened end portion thereof. A stub
shaft 47, on the adapter 45, projects into the end of tubular lever
arm portion 42 and is locked thereto by a rivet or pin. In order
to limit movement of the arm 40, a stop mechanism 60 is fixed to
the shaft 13. The stop mechanism has respective rearward and forward
arms 61 and 62 engageable with the lever arm 40 as it is oscillated
back and forth on the wheel axle defining respectively rearward
and forward movement of the lever arm. The stop mechanism 60 has
a hub 63 with an aperture therein, designated 64, suitably formed
so as to fit onto a nut 16 on the axle 13 in the same manner as
a box-end wrench. Such arrangement permits moving or adjusting the
stop mechanism 60 to different positions locating the lever arms
40 in an appropriate easy to use position for different occupants
of the wheel chair.
The positive drive mechanism 50 (see FIG. 2) includes a short sleeve
51 having one leg of a reverse L-shaped bracket member 52 secured
thereto by two or more threaded studs 53. The other leg of the bracket,
designated 54, has a pin or lug 55 threaded therein as indicated
at 56 and is so located that it can project into apertures 31 of
the annular ring 30 when the lever arm is pushed outwardly transverse
to the plane of the wheel by the occupant of the chair. The sleeve
51 is either press-fit onto the tubular member 42 or in sliding
fit therewith and retained in appropriate position by a rivet or
pin 57. A portion of the ring 30 is located in the gap between the
bracket leg 54 and the sleeve 51 with a relatively small clearance
on each of opposite faces of the ring. The occupant by pressing
outwardly on the arm 40 causes flexing of the arm (or through suitable
pivotal movement as may be provided by bearing 46) such that pin
55 projects into an aperture 31 in the annular ring. The occupant
then, by moving the lever arm forwardly or backwardly, is able to
propel the wheel chair by way of the positive drive mechanism. The
occupant, by pulling the arm inwardly toward himself, causes friction
pads 59 on the sleeve 51 to engage a face of the annular ring effecting
a braking action or, alternatively if desired, a friction drive
rather than a positive drive for the wheel.
In order to prevent accidental movement of pin 55 into an aperture
31 there is provided a compressible means on the drive mechanism
that is engageable with a side face of the annular ring. The compressible
means illustrated in FIG. 2 consists of a sleeve 55A, made preferably
of a plastics material, slidably mounted on pin 55. The sleeve 55A
is spring biased outwardly from the bracket leg 54 toward the ring
30 by a spring 55B. The sleeve 55A is slidable along the pin 55
into a circular recess 54A in the bracket leg 54 and in order to
limit the movement of the sleeve in a direction toward the annular
ring, there is a flange 55C internally of the sleeve and which engages
a face of the head 55D of the bolt 55. As an alternative the compressible
means may be a piece of foam rubber or any readily compressible
material located in the gap and secured to the bracket leg 54.
In the embodiment illustrated, apertures 31 extend through the
ring from one side face of the ring to the other. It will be obvious
however, these need only be spaced apart recesses in a side of the
ring that faces the lug or pin 55. Positive engagement can also
be effected by notching or having teeth on one or the other of the
inner and outer peripheral surfaces of the ring. In the event the
outer peripheral surface is notched the positive drive mechanism
would have to be inverted with reference to FIG. 2 and the ring
mounting bolts 32 moved toward the inner peripheral surface of the
ring. |