Brakes – Vehicle
Patent
1997-05-05
2000-08-22
Butler, Douglas C.
Brakes
Vehicle
188 5, A61G 510, B32B 504
Patent
active
061057312
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a braking device for wheeled chairs, the device including at least two brake legs, which are lowerable and retractable in accommodating tubular members disposed on the chair frame for positionally oriented vertical leg movement to, and from a substructure, this movement being actuated by urging means situated above each leg, and fastened to a shaft such as to perform turning movements moving the legs to, and from their braking position when the braking device is activated or deactivated.
In structures of a similar type, including brake legs for arresting the movement of a wheeled chair, there have been problems when the chair passes over thresholds and the like, since the legs in their inactive positions have got caught in such obstructions during passage of the chair. This has resulted in that when the obstruction has a height great enough for the legs to get entangled with it, the person sitting on the chair has much trouble with extrication from this situation, without help from another person.
The object of the present invention is to achieve a braking device of the kind where the brake legs, in their inactive positions, are at a height above the substructure which is sufficient to prevent them from catching on thresholds or other objects projecting up from the substructure, while maintaining effective and simple actuation of the legs. The distinguishing features of the invention are disclosed in the accompanying claims.
Due to the invention, there has now been achieved a braking device for a wheeled chair that meets its objectives in an excellent manner, while being simple and cheap to manufacture. The urging means for each leg comprises a cam, which, due to its special implementation, obtains a very large amount of travel for the vertical movement of the leg. Accordingly, the cam profile is formed as an elongate S, which not only affords long leg travel, but also ease of cam operation. Since the bottom of the leg may now lie well above any expected obstruction projecting from the substructure when the leg is in its retracted, or inactive position, there are no longer any problems with the legs catching on such obstructions, e.g. thresholds, during passage of the chair over them.
The invention will now be described in more detail below with the aid of a preferred embodiment example, and with reference to the accompanying drawings, where:
FIG. 1 is a side view of the inventive braking device, when its legs are in a retracted state.
FIG. 2 is a sectional side view along the line II--II in FIG. 1.
FIG. 3 is an exclusive side view of the cam in accordance with the invention, and
FIG. 4 is an end view of the cam in FIG. 3.
In FIGS. 1 and 2 will be seen an inventive embodiment of a braking device 1 intended for a wheeled chair, and including at least two legs 2, 3, which are lowerable against, and raisable from a substructure, e.g. a floor. The legs 2, 3 are positionally, vertically oriented in their movement by their accommodation in tubular members 4, 5 fixed to the chair frame. Leg movement is actuated by urging means 6, 7, which are situated above the respective leg and are caused to turn by a shaft 8, to which they are fixed. Turning the means 6, 7 anti-clockwise, as seen in FIG. 1, causes the means to urge legs 2, 3 downwards into contact with the substructure for arresting movement of the chair.
The urging means 6, 7 comprise cams 9 and 10, which have their turning axes coincident with the axis 11 of the shaft 8 and are fixed to it. The cams 9, 10 have their profiles 12, 13 coacting with ball bearings 18, 19 accomodated in the upper parts 16, 17 of the legs 2, 3, the profiles being formed with an elongate S configuration for obtaining maximum travel of the free ends 14, 15 of the legs from the substructure. In the upper, inactive position of the legs, where the wheeled chair is not braked, the ball bearings 18, 19 engage against the inwardly curved portion of the cam profiles 12, 13. The legs are urged upwardly into engagement with the cam profiles with the aid of hel
REFERENCES:
patent: 2185073 (1939-12-01), Chamberlain
patent: 3288250 (1966-11-01), Oja et al.
patent: 4302025 (1981-11-01), Waddell et al.
Butler Douglas C.
Mercado Medic AB
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