A SKI ASSEMBLY FOR A WHEEL CHAIR

SKI POUR FAUTEUIL ROULANT

English Abstract

A ski assembly for a wheelchair is described, which includes a ski having a tip, a heel opposed to the tip and a wheel receiving opening. An axle support bracket is secured to the ski. An axle is mounted to the axle support bracket. The axle extends transversely over the wheel receiving opening. A ground engaging wheel is rotatably mounted on the axle and extends through the wheel receiving opening. The wheel supports the ski in an operative position above and substantially parallel to a groundsurface. A mounting bracket is fixed to the axle. The mounting bracket mounts the ski to a wheelchair for 360 degree rotation about a substantially vertical axis. The length of the ski is sized to permit unobstructed 360 degree rotation.

French Abstract

Un ensemble de ski pour un fauteuil roulant est décrit, qui comprend un ski ayant une extrémité, un talon à l'opposé de l'extrémité et une ouverture pour accueillir une roue. Un support d'essieu est fixé sur le ski. Un essieu est monté sur le support d'essieu. L'essieu s'étend transversalement au-dessus de l'ouverture pour accueillir une roue. Une roue engageant le sol est montée rotativement sur l'essieu et s'étend par l'ouverture pour accueillir une roue. La roue soutient le ski en une position de fonctionnement au-dessus et sensiblement parallèle à une surface de sol. Un support de montage est fixé sur l'essieu. Le support de montage fixe le ski sur un fauteuil roulant pour une rotation à 360 degrés autour d'un axe sensiblement vertical. La longueur du ski est conçue pour permettre une rotation libre à 360 degrés.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. ~A ski assembly for a wheelchair, comprising:
a. ~a ski having a tip, a heel opposed to the tip and a wheel receiving
opening;
b. ~an axle support bracket secured to the ski;
c.~an axle mounted to the axle support bracket, the axle
extending transversely over the wheel receiving opening;
d. ~a ground engaging wheel rotatably mounted on the axle and extending
through the
wheel receiving opening, whereby the wheel supports the ski in an operative
position above and
substantially parallel to a groundsurface; and
e. ~a mounting bracket fixed to the axle, the mounting bracket including means
for
mounting the ski to a wheelchair for 360 degree rotation about a substantially
vertical
axis, the length of the ski being sized to permit unobstructed 360 degree
rotation.
2. ~The ski assembly for a wheelchair as defined in Claim 1, the wheel
protruding less than
one inch below the ski.
3. ~The ski assembly for a wheelchair as defined in Claim 1, the ski being
pivotally movable
about a horizontal axis represented by the axle.
4. ~The ski assembly for a wheelchair as defined in Claim 3, biasing means
being provided to
maintain the ski in the operative position.
5. ~The ski assembly for a wheelchair as defined in Claim 1, the ski having
opposed sides
with the wheel receiving opening being centrally positioned between the
opposed sides.

8
6. A ski assembly for a wheelchair, comprising:
a. a ski having a tip, a heel opposed to the tip and a centrally positioned
wheel
receiving opening;
b. an axle support bracket secured to the ski;
c. an axle mounted to the axle support bracket, the axle
extending transversely over the wheel receiving opening;
d. a ground engaging wheel rotatably mounted on the axle and extending through
the
wheel receiving opening to protrude by less than one inch below the ski,
whereby the wheel
supports the ski in an operative position above and substantially parallel to
a groundsurface; and
e. a mounting bracket pivotally mounted to the axle for movement about a
substantially horizontal axis defined by the axle, the mounting bracket
including a male adaptor
for mounting the ski to a wheelchair for 360 degree rotation about a
substantially vertical axis,
the length of the ski being sized to permit unobstructed 360 degree rotation;
and
f. a spring extending between the axle support bracket and the mounting
bracket,
thereby providing a biasing force to maintain the ski in the operative
position.

9
7. ~In combination:
a wheelchair; and
a ski assembly, comprising:
a. ~a ski having a tip, a heel opposed to the tip and a centrally positioned
wheel
receiving opening;
b. ~an axle support bracket secured to the ski;
c. ~an axle mounted to the axle support bracket, the axle
extending transversely over the wheel receiving opening;
d. ~a ground engaging wheel rotatably mounted on the axle and extending
through the
wheel receiving opening to protrude by less than one inch below the ski,
whereby the wheel
supports the ski in an operative position above and substantially parallel to
a groundsurface; and
e.~a mounting bracket pivotally mounted to the axle for movement about a
substantially
horizontal axis defined by the axle, the mounting bracket including a male
adaptor for mounting
the ski to a wheelchair for 360 degree rotation about a substantially vertical
axis, the length of
the ski being sized to permit unobstructed 360 degree rotation; and
f. ~a spring extending between the axle support bracket and the mounting
bracket,
thereby providing a biasing force to maintain the ski in the operative
position.

Description

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21D~3~~
The present invention relates to a ski assembly for a
wheel chair.
BACKGR~iJI~ID OF T~iE INVENTI01~1
A wheelchair is constructed with a pair of large rear
wheels and a pair of small front castor wheels. It is very
difficult for a wheelchair user to manoeuvre through
accumulations of snow during the winter. The small front
castor wheels tend to become bogged down in the snow or catch
on ridges hidden under the snow. When others render assistance
by pushing the wheelchair from behind, it merely serves to push
the front castor wheels further into the snow. An obvious
solution to alleviate this problem would be to attach skis to
the wheelchair in place of the small front castor wheels; for
skis are known to be better suited for manoeuvring through the
snow.
Wheelchairs are rarely, if ever, seen equipped with skis
for a number of reasons. One reason is that skis are unable
to move effectively over a groundsurface that is not covered
by snow. It is not practical for a wheelchair user to have two
wheelchairs; one suited for indoor use and the other suited for
outdoor use. Even if a wheelchair equipped with skis was
dedicated to outdoor use, when maneuvering around a
neighbourhood a person in a wheelchair will inevitably
encounter stretches of sidewalk without snow cover. Another
reason is that attaching skis to the wheelchair can adversely
effect its maneuverability. The small front castor wheels of
the wheelchair are capable of 360 degree rotation about a
vertical axis. This movement is critical to enable a
wheelchair user to turn, back up and manoeuvre within a
restricted area. These factors make the "winterizing" of a
wheelchair different than other applications where wheels are
replaced with skis to facilitate winter use.

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SUI~~IARY OF THE INVENTION
What is required is a ski assembly for a wheelchair which
permits indoor use and does not limit maneuverability.
According to the present invention there is provided a ski
assembly for a wheelchair which includes a ski having a tip,
a heel opposed to the tip and a wheel receiving opening. An
axle support bracket is secured to the ski. An axle is mounted
to the axle support bracket. The axle extends transversely
over the wheel receiving opening. A ground engaging wheel is
rotatably mounted on the axle and extends through the wheel
receiving opening. The wheel supports the ski in an operative
position above and substantially parallel to a groundsurface.
A mounting bracket is fixed to the axle. The mounting bracket
includes means for mounting the ski to a wheelchair for 360
degree rotation about a substantially vertical axis. The
length of the ski is sized to permit unobstructed 360 degree
rotation.
The ski assembly, as described, creates what could be
considered as a "caster ski" which is rotatable about 360
degrees. The wheel protrudes below the ski to enable the
wheelchair to roll over a groundsurface which is clear of snow.
When snow cover is encountered that exceeds in depth the amount
to which the wheel protrudes, the wheelchair becomes supported
by the ski.
Although beneficial results may be obtained through the
use of the ski assembly, as described, problems may be
encountered in climbing steep curbs. When a wheelchair user
encounters a curb or similar raised area, he "climbs" the curb
by tipping the wheelchair to place the small front caster
wheels on top of the curb. When the curb is steep the skis can
get in the way and prevent the wheelchair user from placing the
wheels of the ski assembly on top of the curb. Even more
beneficial results may, therefore, be obtained when the ski is

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pivotally movable about a horizontal axis represented by the
axle. When the ski is pivotally movable it moves out of the
way in response to a pressure exerted by the curb.
Although beneficial results may be obtained through the
use of the ski assembly, as described, in some circumstances
skis pivotable about a horizontal axis can present a nuisance
or even a hazard to a wheelchair user. For example, if the ski
is overbalanced and pivots toward the heel, the heel will drag
along the groundsurface making an annoying noise which
constitutes a nuisance. Similarly, if the ski pivots to assume
a substantially vertical position when a wheelchair user is
lowering himself down off a curb, the ski can dig into the
groundsurface causing the wheelchair to tip backwards. Even
more beneficial results may, therefore, be obtained by
providing biasing means to maintain the ski in the operative
position. When biasing means is provided there is greater
control over the ski and it will not flop into a position which
will present either a nuisance or a hazard.
ao
BRIEF DESCRIPTION OF THE DRATnTINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a top plan view of a ski assembly for a
wheelchair constructed in accordance with the teachings of the
present invention.
FIGURE 2 is a side elevation view of the ski assembly for
a wheelchair illustrated in FIGURE 1.
FIGURE 3 is front elevation view of the ski assembly for
a wheelchair illustrated in FIGURE 1.
FIGURE ~ is side elevation view of a wheel chair equipped
with the ski assembly illustrated in FIGURE 1.
FIGURE 5 is. top plan view of the wheel chair illustrated
in FIGURE 4.

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DETAILED DESCRIPTION OF THE PREFERRED EMEODII~iEN'1'
The preferred embodiment, a ski assembly for a wheelchair
generally identified by reference numeral 10, will now be
described with reference to FIGURES 1 through 5.
Ski assembly 10 includes a ski 12 having a tip 14, a heel
16 opposed to tip 14 and a centrally positioned wheel receiving
opening 18. An axle support bracket 20 is secured to ski 12.
An axle 22 is mounted to axle support bracket 20. Axle 22
extends transversely over wheel receiving opening 18. A ground
engaging wheel 24 is rotatably mounted on axle 22. Ground
engaging wheel 24 extends through wheel receiving opening 18
and protrudes slightly less than one inch below ski 12. A
mounting bracket 26 is pivotally mounted to axle 22 permitting
relative pivotal movement between mounting bracket 26 and ski
Z2 about a substantially horizontal axis defined by axle 22.
Mounting bracket 26 includes a male adaptor 28. Male adaptor
28 is adapted to be received in a female receptacle (not shown)
within a wheelchair 11, in a like manner to that in which front
castor wheels of wheelchairs are presently attached, as
illustrated in FIGURES 4 and 5. Referring to FIGURES 4 and 5,
when mounted to wheelchair 11, as described, ski assembly 10
is capable of 360 degree rotation about a substantially
vertical axis defined by male adaptor 28 in a like manner to
a castor wheel. It will be appreciated that the length of ski
12 must be of such a size to permit unobstructed 360 degree
rotation. A torsion spring 30 extends between axle support
bracket 20 and mounting bracket 26. Spring 30 provides a
biasing force to maintain ski 12 in an operative position above
and substantially parallel to a groundsurface.
The use and operation of ski assembly 10 will now be
described with reference to FIGURES 1 through 5. Ski assembly
10 is installed on wheelchair 11 by inserting male adaptor 28
into the female receptacle on the wheelchair that normally

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2~04~2~
receives the front castor wheels. Once installed the
wheelchair will function normally in the confined spaces of a
residence with the ski assembly rotating 360 degrees within the
female receptacle about a substantially vertical axis defined
5 by male adaptor 28, as illustrated in FIGURE 5. It is
preferred that wheel receiving opening 18 be centrally
positioned to facilitate 360 degree rotation. To better adapt
ski assembly 10 far outdoor use as will hereinafter be
described, relative pivotal movement is provided between
mounting bracket 26 and ski 12 about a substantially horizontal
axis defined by axle 22. Spring 30 maintains ski 12 in a
substantially horizontal operating position, so that ski 12
does not pivot resulting in heel 16 being dragged across the
floor.
When used out of doors ski assembly 10 permits wheelchair
11 to glide over any snow cover that exceeds one inch in depth.
Wheel 24 protrudes below ski 12 for less than one inch which
results in the front of wheelchair 11 being fully supported by
ski 12. Protruding wheel 24 acts as a rudder providing some
directional stability. Spring 30 improves the control the
wheelchair user has over ski 12. When a curb or like obstacle
is encountered, spring 30 provides stability to ski 12 so that
ski 12 does not pivot wildly when ski assembly 10 is off the
ground. This alleviates any danger of heel 16 of ski 12
catching on the groundsurface and flipping wheelchair 11 over:
The pivotal mounting about a horizontal axis defined by axle
22, enables ski 12 some movement when subjected to pressure
from obstacles. Spring 30 biases ski 12 back into the
operative position when the pressure is removed.
It will be apparent to. one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as defined
by the claims. For example, having ski 12 pivotally mounted
' with biasing by spring 30 enhances performance but is not

,.-.
absolutely essential. A workable embodiment could be
constructed with ski 12 rigidly fixed to mounting bracket 26.

Representative Drawing