Braking device for wheeled chairs

Du Rees, Stephan;

The invention relates to a braking device for wheeled chairs, the device (1) including at least two brake legs (2, 3) which can be lowered to, or raised from a substructure while being positionally movement-oriented with the aid of tubular members (4, 5) fixed to the chair frame, these vertical leg movements being actuable via urging structure (6, 7) situated above the respective brake leg for performing a turning movement with the aid of a shaft (8), to which they are fixed, this movement resulting in one direction in arresting the chair moving the legs (2, 3) downwards into their braking position, and in the opposite direction in upward movement of the legs into their inactive position. The urging structure comprise cams (9; 10) having their turning axis (11) coincident with the longitudinal axis of the shaft (8) to which they are fixed, their profiles (12; 13) having an elongate S-shape, and coact with the upper parts (16, 17) of the legs for obtaining maximum lifting height of the leg free ends (14, 15) from the substructure.

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.

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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 helical springs 20, 21.

For achieving as great a lifting height as possible for the legs 2, 3 the vertical travel of the legs substantially corresponds to the radius of the radial turning movement of the cams, and this turning radius is substantially twice as long as the lateral extension of the cam profile from a vertical plane through the turning axis 11, when the cam is in its downwardly turned, vertical position. In order to keep the friction between profiles 12, 13 and the upper parts 16, 17 of the legs 2, 3 as small as possible, the legs are provided with the already-mentioned ball bearings 18, 19. These are fitted on bearing supports 31' and 32' on the respective leg.

The shaft 8 is rotatably mounted in the upper portions 22, 23 of the tubular members 4, 5 and extends beyond them at either end 26, 27. At least one lever retainer 24, 25 is fixed to the respective end 26, 27, and accommodates a brake lever 28 provided at its free end with a knob 33 for facilitating its operation. This lever can thus be inserted optionally in retainer 24 or 25. For preventing the legs 2, 3 from turning in the tubular means 4, 5 the latter are each provided with a longitudinal groove in its bore, for coaction with the respective pin 29, 30 fixed to the legs 2, 3. The grooves are not shown on the drawing.

The free ends 14, 15 of the legs are provided with pads 31, 32 for obtaining gentle and effective engagement against the substructure.

The braking device in accordance with the present invention functions in the following way. In its inactive state, the legs 2, 3 of the device are in an upper position, and are kept there by the bias from helical compression springs 20, 21 housed in the tubular members 4, 5. Thus, when the brake is applied the brake lever 28 is manually pushed or pulled in an anti-clockwise direction in FIG. 1, which turns the shaft 8. In its movement the shaft takes with it the cams, their profiles working against the ball bearings to urge the legs downwards into their active positions with their braking pads 31, 32 engaging against the substructure. For releasing the brake, the lever 28 is moved in a clockwise direction, the legs moving upwards as their bearings follow the cam profiles, which is ensured by the action of the springs urging the upper parts 16, 17 in an upward direction. This spring bias also ensures that the ball bearings are kept against the profile part with the least radius to the rotational axis 11, i.e. the legs are kept in their highest position. A notch 32" is provided in the cam profile at its maximum radius to the turning axis 11, i.e. when the brake is fully "on". This fixes the cam in relation to the bearing until force is applied to the brake lever, thus ensuring against untoward movement of the cam, since spring bias urges the bearing against the notch. Instead the manual operation of the lever 28, an electrically driven means may be arranged to actuate the shaft 8.