Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITL~:: WHEE:LCIIAIRS
This invention relates to wheelchairs for handicapped
people and, in particular, to the transfer o~ such wheelchairs
into motor vehicles.
Transferrin~ a handicapped person from a wheelchair
into a seat of a mo-tor vehicle is frequently a painful and
hazardous operation. Vehicles such as vans, small buses,
and ambulances are therefore sometimes equipped with tail-
lift mechanisms which enable wheelchairs to be lifted and
driven into the back of the vehicle. But such mechanisms
are cumbersome and unsuited for use in a normal family-
sized car.
In one previous proposal for transferring a t~leel-
chair into a fa~ily car, a revolving pla-tform is ~itted in
the car in place of the normal seat. In use, a ramp is
extended from the platform on-to the kerb or road, and the
wheelchair is manoeuvered up the ramp onto the platform.
The pla-tform is then revolved to bring the wheelchair to
its front-facing position. This mechanism requires a wheel-
chair which can be adjusted to reduce its height for
posi-tioning in the car. Once inside the car, the wheelchair
is locked in position and is intended to be used 2S a driving
sea-t if required.
- Qn advantage of this prior proposal is that the ~heel-
chair occupant can e~ter or leave the car without having to
~et out of the wheelchair. On the other 'nand, the mechanism
is complicated and, with the variation in seating layout
and size of doorways, it is unlikely that the unit could
be fitted in a wide range of cars unless it were
separately designed for each car model. Moreover, since
the ramp angle would be steep when entry was from the
road rather than rom the kerb, the mechanism would need
to be powered externally for many wheelchair occupants
who would lack the strength to push themselves up the
ramp.
Another prior proposal is described in sritish patent
1,226,402. In this system an invalid chair is lifted
from a wheeled based by a hoisting mechanism fixed in
the vehicle, it is then swung about a vertical axis
of the hoist mechanism so that the chair passes through
the door opening, and finally it is lowered into
position within the vehicle. The chair is connected
to the hoist mechanism by a linkage consisting of upper
and lower pairs of arcuate arms, the two u~per arms and
the two lower arms each being joined at a central pintle,
and the arms being locked from pivoting on the central
pintles by a rigid stay spanning the two upper arms. The
jointed arms in such a mechanism make it difficult to
control,the chair being spaced from the hoist mechanism
by the length of the double arm linkage until it reaches
the door opening, and the linkage then being folded to
allow entry of the chair into the vehicle. A further
disadvantage is that, whenever the vehicle arrives at
its destination, there must be a wheeled base available
if the wheelchair occupant is to be able to leave
the vehicle.
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In accordance with the present invention there is
provided a wheelchair for handicapped or elderly persons,
comprising a generally rectangular box-like frame, a seat
supported in the frame, the frame being supported on at
least three wheels when resting on the ground and each of
the wheels being retractable toward the frame when the
wheelchair is lifted off the ground to facilitate transfer
of the suspended chair through a door opening in a motor
vehicle, and means for oppositely inclininy the axes of at
least the two rear wheels when the wheels are retracted to
reduce the track width at the base of the chair~
Preferably, each rear wheel is rotatable about an
axle located at one end of a swing arm, the other end of the
swing arm being pivotable about a fixed horizontal axis, and
the arm being displaceable between an extended operative
position an~ a retracted inoperative position.
By way of example only, an embodiment of the invention
will now be described with reference to the accompanying
drawings in which:
Fig. 1 is a side view of a motor car showing a wheelchair
ready for transfer into the car,
Fig. 2 is a diagrammatic side view of the wheelchair and the
transfer mechanism,
Fig. 3 is a perspective view of the wheelchair and transfer
mechanism,
Fig. 4 is a plan view of the wheelchair and transfer mechanism
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Fig. 5 is a side view of a self-propelled wheelchair
embodying the invention,
Fig. 6 is a front view of a portion of the chair shown
in Fig. 5 and showing the rear suspension,
Fig. 7 is a plan view of the portion of the chair shown
in Fig. 6,
Fig~ ~ is a side view of the chair of Fig~ 5 shown in
its folded configuration,
Fig. 9 is a side view of an alternative rear wheel
retracting mechanism showing the rear wheels down.
Fig. 10 is a front elevation on line A-A of ~ig. 9
showing one rear wheel down and the other retracted,
Fig. 11 is a plan view on line B-B of Fig. 9 showing
the left hand set of wheels up or retracted and the right
hand wheels down or extended (as viewed by the wheel-
chair occupant),
Fig. 12 is a side view similar to that of Fig. 9 but
showing the wheels retracted,
Fig. 13 is a detail of the transfer mechanism shown in
Figs. 1 to 4,
Fig. 14 is a diagrammatic side view of the chair shown
in Fig. 5 and illustrating the seat folding mechanism
with the backrest in its upright position,
Fig. 15 is a view similar to that o~ Fig. 14 showing
the backrest in its reclining position, and,
Fig. 16 is a view similar to that of Fig. 14 showing
the hair in its collapsed, folded con~iguration.
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As illustrated in Figs. l to 4, the transfer mechanism
includes a lifting device and a swivel linkage. The
wheelchair is constructed so that it has sufficient
strength to be lifted, complete with the occupant, from
either flat ground or kerbing, by the liting device
which is fixed in the car. The lifting device and
linkage lift and transfer the wheelchair, complete with
its occupant, through the doorway of any small car or
van, and then lower and lock the wheelchair into the
normal seating position, and vice versa.
The lifting device includes a vertical, square-section
tube lO fixed to the floor ll and to the top rail 12
of the car. The tube lO is located just to the rear
of the proposed seat position but, alternatively,
may lie adjacent the front door post.
Slidably mounted on the tube 10 is a sleeve 13 which
is slightly larger than the tube lO and slides up and
down on roller bearings. The sleeve 13 carries the
linkage mechanism, and is operated by mechanical,
electrical, hydraulic, or pneumatic jack means 14.
If a hydraulic or pneumatic jack is used for lifting
the sleeve 13, initial actuation of the jack lowers a
stabilising foot 15 between the floor of the car and
the ground so that any sag of the car suspension when
lifting the chair is eliminated.
The linkage mechanism consists of two general]y vertical
plates 16 and 17 hinged on both vertical edges. In
practice the plates may be inclined at about 6 to the
vertical to compensate for both road camber and the
lean of the vehicle due to the offset weight of the
chair and occupant during a transfer operation. The
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rear, or inner, edges are pivoted on fixed plates 18 and 19
projecting from the top and bottom of sleeve 13, and the
front, or outer, edges are pivoted onto a transfer plate
20 (or a pair of transfer arms) carrying a vertical
conical pin 21 which locates in a hole 2~ ormed in a
hracket 245 secured at a top rear corner of a tubular
rear frame 242 of the wheelchair. This is shown most
clearly in the detail of Fig. 13.
The pin 21 comprises the machined end of a suide rod 23,
and a foot lever 22 secured to the bottom of the frame
242 includes a recessed portion 22a for engaging the guide
rod 23. This arrangement allows the chair to be attached
to the hoist mechanism even though the chair may be
resting on a camber of up to 15.
In operation, the wheelchair is reversed up to the open
doorway of the car. With the sleeve 13 in its lowered
position and the linkage arms 16, 17 in their extended
position as shown in Fig. 4, the chair is aligned so that,
when the outer tube 13 is raised, the conical pin 21
locates in the bearing 24 at the top rear corner of the
chair frame. Further operation of the lifting device
then lifts the chair off the ground and, as soon as it
is high enough, the wheels 26, 27 and 28 are retracted
into the frame (as shown in Fig. 3). The chair is then
free to be transferred to the car.
The vertical plates 16, 17 are then swung through a small
arc to their retracted position shown in dashed outline
in Fig. 4, and this draws the chair laterally part-way
into the vehicie while the occupant remains facing outwards
with his back to the door opening. The chair is then
rotated about the pivot 21 to face the front of the vehicle.
Since the chair is suspended at a rear corner of its frame,
this final pivoting of the chair simultaneously transfers
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the chair sideways by an amount almost equal to the full
width of the chair and thereby completes its lateral
transfer into the vehicle.
The chair is then lowered until it rests on a frame
secured to the rloor of the car, and it is releasably
locked in this position by any convenient locking mechan-
ism. The whole transfer process, if required, can be
powered.
One advantage of the arrangement is that the occupant
does not have to double-up to pass beneath the car's
gutter ~O during the transfer process. During rotation of
the chair about the pivot 21, the occupant may lean
outwards to keep his head clear of the gutter ~O,and he
can then wait until the chair has been lowered before
bringing his head inside the vehicle.
The method of transer requires a very strong wheelchair.
To achieve this, the structure of the chair may be a metal
or fibreglass monocoque with a box-like tubular sub-frame.
In the embodiment of Figs. 1 to 8, the four wheels 26,
27, 28 and 32 are retracted into the frame alongside the
seat 29 of the wheelchair and into the respective hollow
arms 30 and 31. This reduces the overall height of the
chair and so allows it to be transferred with its occupant
through the average side door opening of a car.
The wheelchair does not fold in the normal way (sides
together) but is constructed so~that the back folds forward.
This, together with the retractable wheels, enables
folding of the chair to a compact size considerably
smaller than that achieved by normal collapsible chairs.
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The wheelchair m~y be attendant, self or electrically
propelled. In the self-propelled model, a 'capstan'
wheel is provided which can be of varying sizes but will
be situated alongside the occupant and will be connected
to the road wheels via a chain or belt. The capstan
wheel 100 is illustrated diagrammatically in Fig~ 5. The
capstan wheel is easily changeable allo~ing for the
provision of varying surface textures and/or shapes, and
varying gear ratios for differing disabilities and
strengths of the wheelchair occupant. Not only does this
enable the disabled person to choose a wheel particularly
suitable for his handicap but, because the capstan wheel
is well away from the road wheels, it is in all cases
cleaner for hands and clothing than the usual method
o self-propulsion (another handwheel of slightly smaller
diameter and just outside the road wheel).
In general,the described chair is far stronger and safer
than collapsible wheelchairs at present available
The described transfer process enables the seat to be
swung into a position behind the steering wheel of a car.
Unlike the previously described proposal using a ramp
and revolving platform, this can be done without requiring
any modification to the steering column.
With particular reference now to the self-propelled wheel-
chair shown in Figs. S to 8, the wheelchair is provided
with a 'capstan' 100. The capstan is shown with a smooth
latex rim but this can have any contour or texture; it
is located on a square drive-peg 110 and retained by a clip
120. The drive-pegs are connected to the rear road wheels
via a chain or toothed belt 130.
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The rear wheels 90 are mounted on swing-arms 140 which
rotate about respective stub axles i61 on boearings 160
and which are split and spigotted to allow independent
action, with a brake-rod 170 running down a hollow axis
tube 150. Connected to the swing-arms 140 are links 180
each with rollers at their opposite ends, which in turn
are connected to links 190. Links 180, 190 adopt an
over-centre configuration which retain the links in their
extended positions and prevent premature folding until
there is no weight on the wheels ie. when the chair is off
the ground. Link 190 acts on rubber suspension sprin~
210 under the control of arm 220. A rod 230 secured to
links 190 connects left-hand and right-hand suspensions
and has an 2ngular joint 240 because of the independent
action of both rear wheels 90.
Solidly fixed to rod 230 is lever 250 which operates
the folding mechanism for the rear wheels. Downward
rotation of lever 250 from its position shown in Fig. 5
to its position shown in Fig. 8 rotates each link 190
about its pivotal connection Wlt~ a 9 220 so that the
links 190, 180 and 140 are moved from their extended
positions shown in Fig. 5 to the positions shown in Fig.
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The 'capstan' 100 may be easily removed to assist side
exit and for folding, hence the quick-release catch 120.
The front castors 260 retract by simply rotating in
either direction about axis 270. When the chair is folded
into its "shopping-trolley" configuration (~ig. 8), the
rear wheels can be set down to position 280 allowing the
unit to be pulled along by extending handle 290 which
also acts as the adjustment for the foot-rest 300.
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The back of the wheelchair may be lowered to a reclining
position as shown by the dashed outline in Fig. 5 while
retaining its stabilit~. Stability is maintained because
the seat portion moves forward as the back lowers ~o the
reclining position~, so keeping -the centre of gravity in
approximately the same place i,e, within a short wheel
base, and thus providing the advantages of a recliner
without the usual disadvantage of loss of manoeuvra~ility
due to a long wheelbase.
With additional reference to Figs. 14 to 16, the rigid,
contoured back-rest 320 can recline (Fig. 15) or fold
forward (Fig. 16). In Figs. 5 and 8 the alternative
positions are shown in dotted outline and denoted by the
suffixes A (reclining)and B (folded) against the reference
numerals. Rotation of screw 345 (Fig. 14) by manual or
electric means moves the seat squab 330 forwa~d'or back-
wards according to the direction of rotation. The position
of the squab 330 is controlled by a pair of links 340
(one on each side) at the rear, and by a pair of links 350
(one on each side) at the front. The back-rest 320 is
pivoted to the frame at 323 and is connected to the seat
squab 330 by a pair of connectingl-nks 325 ~one on each
side). Accordingly, forward movement of the seat squab
330 is accompanied by movement of the backrest to its
reclining position shown in Fig.15. The forward movement
of the seat squab compensates for the rearward movement
of the centre of gravity of the occupant as the occupant
reclines so that the centre of gravity is kept virtually
stationary within the short wheelbase. The short wheel-
base is necessary for manoeuvrability.
The orward movement of seat squab 330 can, if required,
also elevate footrest 300 by means of a pin 400 as shown
diagrammatically in Fig. 5. When folding into the config-
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uration of Fig. 8 or Fi~. 16 the footrest 300 (not shown inFig. 16) is contained in the hollow between the seat back
320B and the seat s~lab 330B.
For folding and for when the se~at is fixed in a motor vehicle,
the handles 360 fold down (a safety measure); an alternative
handle 370 is shown in Flg. 5 which has greater height
ad~ustment and would allow the occupant to be pushed whilst
in the semi-reclining position. ~rms 380 can be flipped
over for easy side exit and adjusted for length and angle.
Also shown in Fig. 5 is a control lever 390 for an electric
chair; figure 8 shows, in dotted lines, the positions of two
dry-cell batteries 410.
The main advantage of providing front to back folding rather
than the side folding of conventional wheelchairs is that a
rigid ergonomically designed backrest and seat squab can be
used to give adequate support to the occupant. Since the
occupant may have to spend up to 16 hours per day in the
one seat, and may not have the feeling to tell him of the
discomfort that leads to many physical problems, this can be
of immense benefit.
Referring now to Figs 9 to 12, a modified wheel retraction
mechanism is illustrated in which the rear wheels 90 are no
longer maintained in a vertical plane when retracted. Figs.
9 to 12 also illustrate the basic retraction mechanism of
Figs. 5 to 8 in more detail and like reference numerals
denote like parts in the two sets of figures.
A rear tubular frame 242 and front castor axle~housing 243
are welded to a sheet metal structure 244 to form a complete
chassis or "box-like" frame. The weight o the chair is
bracket
transmitted to the wheels from top rear/ 245 of the frame
via rubber suspension springs 210 held on vertical rods 246.
Movement of rods 246 is controlled by a wishbone link 220
via pivot axis 241 at the bottom and by a hole in the top bracket
245 at the top~ The hole in the top bracket allows up and
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down movement of the vertical rod through the bracket as
the suspension moves. The wishbone links 220 have their
fulcrum at a bearing 247 which i5 welded to the rear of the
rear tubular frame 242. This gives more length to the
wishbone 220 compared to the arrangement shown in Figs. 5
to 8, and therefore reduces its angular movement during
suspension travel. The load is transferred to rear wheels
90 through pivot 241, link 190, link 180, and swing axle 140.
The rear wheels 90 normally rotate about a substantially
horizontal axis 91, each wheel being mounted for rotation
about an axle 92 at one end of the swing link arm 140 as in
the mechanism of Figs. 5 to 8. In Figs. 9 to 12, however, the
arms 140 rotate about stu~ axles 93 inclined rearwardly with
resp~ct to the side members 94, 95 of the sheet metal struct-
ure 244 at an angle e to the central axis 96 i~ the plan view
of Fig. 11.
Accordingly, when lever 250 is pulled down and the links 140,
180 and 190 are moved from their extended configuration of
Fig. 9 to their retracted Fig. 12 configuration, the axles of
the wheels 90 will no longer be horizontal and the wheels will
converge downwardly toward one another as shown on the RH
side of Fig. 10.
The angle of each axle 92 with respect to the axis 96 changes
in both plan and rearward elevations. The change for the
rearward elevation is illustrated on the RH side of Fig. 11
and shows that the wheels 90 are toed-out at an angle ~ when
the wheels are retracted.
This downward convergence and toeing-out of the retracted
rear wheels allows the chair to fit more easily between the
door sill and the central transmission tunnel of a motor
vehicle without reducing the width of the seat, and without
the top of each wheel impeding the thighs of an occupant
seated in the chair.
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In Figs. 9 to 12 each rear wheel ~0 is independently
retractable by operating a respective lever 2so, each
wheel having its own set of links 140, 1~0 and 190. The
links 190 and 1~0 are retained in their over centre
position by means of a spring 97 when the wheels are down.
The lever 250 is secured to the link 190 as shown most
clearly on the LH side oE Fig. 10 so that downward
movement of lever 250 about pivot 241 at the end of link
220 urges link 190 against the bias of spring 97 out of
its over-centre relationship with link 180 and carries
the links to the position shown in Fig. 12.
