Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Casters – Wheels
Patent
1997-06-06
1999-03-02
Mah, Chuck Y.
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Casters
Wheels
16 47, 16 35R, B60B 3300
Patent
active
058755187
DESCRIPTION:
BRIEF SUMMARY
This invention relates to castors, in particular, to castors which may be used on a moving walkway.
Moving walkways are becoming common in places such as airports and shops. When such a walkway is roughly horizontal it is easy to handle loads supported on castors, for example a shopping trolley. However, when such a walkway is on a slope, loads supported on castors can be difficult to manage. To overcome this problem the wheels of specially designed castors are designed to slot into grooves which are provided in the surface of the walkway so that they do not have a surface to rotate against, thereby preventing movement of the load due to rotation of the wheels. GB-A-2085103 discloses such a shopping trolley castor. It comprises a fork having two limbs depending from a bridgepiece, two relatively rotatable discs journalled on an axle which is mounted on and which extends between the limbs, each disc having an annular disc portion and a central aperture. The bearings for the discs are spaced axially from one another on the axle and are separated by a larger diameter cylindrical part of the axle which is surrounded by a loose fitting brake ring which will hang on that cylindrical part without touching the ground when the castor is running on a flat floor whereas it is pressed into frictional engagement with the walkway by the cylindrical part when the rims of the discs drop into grooves of that walkway.
The grooved surface need not be formed by a moving walkway. A static length of a similar surface is often provided in the region of an exit from a supermarket in order to trap the wheels of a shopping trolley so as to inhibit shopping trolleys being taken out of the supermarket by customers. This is known as a trolley trap.
Known types of castor designed specifically for use on moving walkways or to be trapped by a trolley trap are time consuming to assemble and expensive to manufacture. Examples of castors of this type are disclosed by DE-B-2656322, DE-A-2937572, DE-A-3128720. In each of these, as in the castor disclosed by GB-A-2085103, the two wheels are journalled on respective bearings which are side by side, spaced one from the other along the axis of rotation of those wheels.
GB-A-1416992, U.S. Pat. No. 3,822,437 and U.S. Pat. No. 3,894,310 each show a twin wheel castor which has a body by which it is attached to structure it is to support for pivoting relative thereto about a vertical axis. In each case, the two wheels are rotatably mounted on a portion of the body of the castor which is disposed between them. The wheels include integral hollow spigots which fit one within the other. These spigots are, in turn, received in a further spigot which is formed integrally within the portion of the body between the wheels, these castors are designed for light-weight duties such as at the feet of television cabinets or other such furniture which normally is stationary. They are not sufficiently structurally robust for heavy duty applications such as for shopping trolleys.
An object of the present invention is to provide a castor for use on a moving walkway or to be trapped by a trolley trap which is simple and cheap to manufacture.
According to the invention there is provided a castor comprising a fork having two limbs depending from a bridgepiece and two relatively rotatable discs journalled on an axle which is mounted on and which extends between the limbs, each disc having an annular disc portion and a central aperture, wherein the two discs together from a single wheel and the central aperture of each disc is formed by a respective axially projecting tubular portion, one of the tubular portions extending over a major part of the spacing between the limbs and being supported along its axial length by a bearing for rotation of the single wheel on the axle, the other tubular portion being supported along a substantial part of its length by said one tubular portion which provides a plain bearing support for said other tubular portion and which allows rotation on the axle of one of the discs relative to the oth
REFERENCES:
patent: 2895160 (1959-07-01), Clifton
patent: 3894310 (1975-07-01), Screen
patent: 5787547 (1998-08-01), Joseph et al.
Flexello Limited
Gurley Donald M.
Mah Chuck Y.
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