Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-04-29
2003-03-11
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Attachment
C280S647000, C280S650000
Reexamination Certificate
active
06530598
ABSTRACT:
FIELD OF INVENTION
The present invention relates to anti-tip devices for wheeled conveyances such as wheelchairs, wheeled conveyances including such anti-tip devices and more particularly to wheelchairs using such anti-tip devices that control forwards, sideways and backwards tipping and methods related thereto.
BACKGROUND OF THE INVENTION
The wheelchair is one of the most important therapeutic devices in rehabilitation, as well as being a well known transportation appliance that enables an infirm, disabled and/or unwell person to move about with greater mobility than they would otherwise be able to do. A conventional wheelchair typically includes a frame, two rear wheels of large diameter and two forward wheels of smaller diameter, a seat and backrest. The seat and backrest are disposed on and secured to the frame so as to form a chair-like structure. The seat can be a padded seat, a solid seat, a sling seat or a seat comprised of webbing. The wheels, seat, and backrest typically are configured and arranged on the support frame so the greater part of the weight of the wheelchair occupant is resting on the rear wheels.
A number of studies have been performed concerning wheelchair safety. These studies have reported occurrences of acute injuries that were serious enough to cause the injured person to seek emergency medical attention and in some cases resulted in fatalities. Although there are a number of causes for such accidents, in a majority of cases the stability of the wheelchair, or the lack thereof, was a factor.
One very common hazard when using wheelchairs is that of tipping over backwards (i.e., rear-tipping accidents). Rear-tipping accidents typically occur when a wheelchair user leans backward, rapidly accelerates forward, wheels up an incline or strikes a low obstacle while wheeling backwards, particularly if the user's center of mass is higher and farther back than usual, such as is the case with users who do not have legs. The reaction to the torque applied to the rear wheels provides a considerable tendency to tipping. When there is any additional factor such as going up a ramp, a hill or a curb, the risk of rear tipping increases further. Other tipping accidents include those in which the wheelchair tips forward or sideways.
As to rear-tipping accidents, many wheelchair manufacturers provide rear anti-tip devices to help limit the extent of rear tipping as an option for the wheelchair. These devices typically comprise rearwardly extending structures, with or without wheels, that prevent more than a minimal amount of rearward tilting. These structures, however, cause problems at the lower end of inclines much like scrapping the rear undercarriage of a car when starting up a steep driveway, in other words, they limit the departure angle of the wheelchair. Also, to the extent that such structures protrude beyond the rearmost aspect of the rear wheels, they tend to make the wheelchair unwieldly in close-quarters maneuvering such as in elevators, hallways, and with crowds of people. A low departure angle also prevents a wheelchair from being tipped back sufficiently to allow the front wheels or casters to clear obstacles such as curbs or so the wheelchair could be pushed over rough round. Such devices are shown for example in U.S. Pat. Nos. 3,848,883, 5,143,391 and 4,565,385.
In sum, to increase stability using such types of anti-tip devices, the device is designed so as to minimize or decrease the departure angle. When this is done, however, then the wheelchair becomes more unwieldly to use. As a result, the anti-tip devices are not used or are configured by the user in some cases so as to form some sort of compromise between stability and the usability or maneuverability of the wheelchair.
Other rear anti-tip devices have been developed that are only put into an operable condition upon some action by the user or by a third party. Until the anti-tip device is put into the operable condition, the device is not effective in minimizing or preventing the wheelchair from tipping over such as in a backwards or forward direction. When the anti-tip device is put into its operable condition, then the device either is subject to the same limitations of other rear anti-tip devices, as described hereinabove, or the operable condition of the anti-tip device effectively renders the wheelchair immobile. Examples of such devices are illustrated in U.S. Pat. Nos. 4,877,260, 5,181,733, 5,564,512, and 5,137,295.
It also is highly desirable for some wheelchair users to develop and master the skill of performing a wheelie when doing certain tasks. The wheelie is a highly useful skill that enables the wheelchair user, for example, to overcome a number of environmental obstacles such as climbing and descending curbs and ramps and turning in tight spaces.
With a conventional wheelchair, a wheelie involves the wheelchair user lifting the front wheels or casters off the floor so that the combined center of gravity of the user and the wheelchair (minus the rear wheels) is balanced over the rear axle. To “pop” a wheelie, the user accelerates the wheelchair forward while leaning backwards. The user maintains the wheelie by applying corrective forward and backward forces to the rear wheels with the hands or by shifting or altering body position.
Many users of conventional wheelchairs are leery of learning this skill, because of the large risk of completely tipping backwards and of striking one's head on the floor, surface or an object, when performing or attempting to perform a wheelie. Also, many clinicians are reluctant to teach such a maneuver because of this risk. As a result, only a minority of wheelchair users do learn how to perform a wheelie.
As indicated above, to perform a wheelie, the wheelchair user must tilt the wheelchair backwards. However, the above-described rear anti-tip devices are configured so as to minimize the amount of rear tilting by the wheelchair. As such, a wheelie usually cannot be performed with a wheelchair that includes such anti-tip devices or structures. This is so because those devices or structures that maintain stability by limiting the departure angle, as a practical matter prevent a user from establishing the conditions needed for the user to “pop” a wheelie.
There is described in Physical Therapy, Volume 64, No. 5 an aid or device to assist training in balancing on the rear wheels of a wheelchair, what the article refers to as an advanced wheelchair skill and commonly known as a wheelie. The described device consists of two thick steel bars that are each bent in the form of a modified U. Each of the two ends of each bar is equipped with a screw collar clamp. Also, each bar is attached to the rear of the wheelchair by means of the screw clamp collars at two points, the rear upright and the tip bar of the wheelchair. In addition, small rollers are affixed to the terminal bend of each bar.
The article also acknowledges and identifies some shortcomings for the device. In addition to use-related shortcomings, the article provides that the device (i.e., the two bars comprising the device) presents a significant hazard to those walking behind the wheelchair and also increases the turning area required for the wheelchair. It is further provided therein that when the client has attained a certain level of proficiency and confidence the training aid or device is removed, thus the device has limited utility.
It thus would be desirable to provide an anti-tip device that would provide the desired stability to prevent or minimize the risk for completely tipping an apparatus such as a wheelchair in a rearwards direction, yet not result in a corresponding decrease in the maneuverability or usability of the apparatus or wheelchair. It also would be desirable to provide an anti-tip device that is easily adaptable for use to prevent or minimize the risk of tilting in at least one of a forward, rearward or sideways direction. It would be particularly desirable to provide such a device where the wheelchair user could regulate the maximum amount of tilting that is t
Conlin David G.
Daley, Jr. William J.
Edwards & Angell LLP
Lum L.
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