Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Casters – Wheels
Reexamination Certificate
1999-06-28
2001-05-01
Mah, Chuck Y. (Department: 3626)
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Casters
Wheels
C016S020000
Reexamination Certificate
active
06223388
ABSTRACT:
FIELD OF THE INVENTION
Luggage and items of cargo, for example, goods contained in packing cases, have to be manhandled and moved from place to place around airports and other similar locations. They are often moved across conveying surfaces which are either horizontal or inclined. It is known to include in such surfaces friction reducing devices as castors, rollers or ball units, so as to facilitate sliding of the load to be moved over the conveying surface. Conveying surfaces of this type may be fixed, in which case they are usually referred to as ‘decks’, or may be mounted on a wheeled framework so that they can be moved to wherever they are needed, in which case they are called ‘dollies’.
Decks and dollies of this kind are also used in a wide range, of other materials handling applications.
The present invention relates to castor assemblies for use in such decks and dollies.
BACKGROUND OF THE INVENTION
Such castor assemblies are to be regarded as ‘consumables’ in this field. In the United States alone, around two million castor assemblies are used each year. It is, consequently, important that the castor assemblies themselves are of rugged construction so as to minimise wear, that they are mounted on decks or dollies so as to minimise the likelihood of damage and, finally, that they are mounted in such a way that they can be quickly and easily replaced when worn.
In the case of dollies it is also desirable that the dollies themselves should be of lightweight construction so that they can be moved easily from place to place. Most known dollies consist of a sub-frame, provided with wheels, on which the castor assemblies are mounted. A strong and relatively heavy sub-frame is needed to support the castor assemblies but the openings defined by the sub-frame between the castor assemblies are dangerous to personnel, who can easily damage legs and ankles if walked upon and they slip into these openings. In addition, the relatively open sub-frame allows the castors to be damaged in use. It has therefore been usual to close over the sub-frame by means of cover plates which serve to protect the castor assemblies against damage and when a castor “toeplate” is fitted also protect personnel against injury.
The need for both a substantial sub-frame and cover plates to protect the castor assemblies have added to the weight of the dolly.
Decks are used not only in airport buildings and the like but also inside the cargo holds of aircraft themselves, where space and weight is at a premium. In such locations, it is essential that decks be made as shallow as possible so that they do not reduce the usable height of the cargo hold and, hence, the available storage space, any more than is necessary.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention there is provided a castor assembly comprising a wheel, a wheel-plate on which the wheel is mounted for rotation about a first axis and a bearing enabling the wheel-plate to rotate about a second axis at an angle to the first axis, the first axis being offset from the second; the bearing comprising inner and outer bearing rings movable relative to one another, the inner ring being secured for rotation about the second axis with the wheel-plate, the inner bearing ring being disposed generally concentrically within the outer bearing ring and the wheel-plate being disposed generally concentrically within the inner bearing ring so that the inner and outer bearing rings and the wheel-plate together form a substantially planar assembly. Since the wheel-plate and the two bearing rings fit one inside the other in a concentric fashion, the whole assembly can be made very much more shallow than if they were stacked one on top of the other. Industry standards require that the castor assembly wheels protrude above the surface of the deck or dolly by at least 15 mm and it has been usual to use wheels of standard size between 55 mm and 75 mm in diameter. Using the smaller diameter wheels, it is possible utilising castor assemblies in accordance with this aspect of the invention to construct a deck which have a total depth of 60 mm.
Preferably, the depth of the bearing measured in a direction parallel to the plane of the wheel is less than the diameter of the wheel. The depth of the castor assembly excluding the wheel measured in a direction parallel to the plane of the wheel is preferably less than the diameter of the wheel and the castor assembly is disposed about the axis of the wheel.
This is, as mentioned above, important where the castor assembly is to be used in a deck within, for example, an aircraft body, in circumstances where space is limited and a deep castor assembly reduces the space available for storage or transportation of freight. Conveying devices using conventional ‘stacked up’ castor assemblies are typically of the order of 9″ (185 mm) deep and castors are therefore rarely used in aircraft.
The shallowness of the deck construction also has favourable cost implications in that the whole deck can be made more cheaply and the costs implicit in the operation of lifting freight onto the deck are reduced.
In accordance with another aspect of the invention there is provided a conveying device comprising a plate having an upper surface over which objects to be conveyed are moved, in use; the plate having formed therein at least one aperture in which is mounted a castor assembly comprising a wheel mounted on a wheel-plate for rotation about a first axis generally parallel to the surface of the plate and a bearing by means of which the wheel-plate can rotate about a second axis at an angle to the first axis and, hence, to the surface of the plate, the bearing and the wheel-plate being disposed such that they are below the upper surface of the plate so that only a portion of the wheel projects above the said upper surface of the plate.
The wheel-plate and inner and outer bearing rings are preferably such that the inner bearing ring is disposed generally concentrically within the outer bearing ring and the wheel-plate is disposed generally concentrically within the inner bearing ring so that the inner and outer bearing rings and the wheel-plate together form a substantially planar assembly.
By locating the bearing and the wheel-plate on which the wheel is mounted so that only a portion of the wheel projects above the upper surface of the plate, the vulnerable parts of the castor assembly are largely protected from damage caused by impacts from items of freight moving over the conveying device. If, as is preferable, the pivot axis about which the wheel rotates is close to the level of the plate, the torque arising from lateral impacts to the wheel is also minimised.
In a further aspect of the invention, there is provided a conveying device comprising a plate having an upper surface over which objects to be conveyed are moved, in use; the plate having formed therein at least one aperture in which is mounted a castor assembly comprising a wheel mounted on a wheel-plate for rotation about a first axis generally parallel to the surface of the plate and a bearing by means of which the wheel-plate can rotate about a second axis at an angle to the first axis and, hence, to the surface of the plate; the wheel-plate having formed therein a slot in which the wheel is received, the edges of the slot fitting closely around the wheel so that the bearing, wheel-plate and wheel together substantially completely fill the aperture in which the castor assembly is mounted.
With this arrangement, there is very little open space around the wheel into which a worker can inadvertently put a foot or hand and consequently the risk of injury to those involved in moving freight using such conveying devices is much reduced. In addition, because the wheel-plate and bearing ring assembly more or less fills the apertures formed in the plate, the whole structure is considerably stronger than would be the case if the apertures were left unfilled. As a result, the subframe needed to support the plate and its associated castor assemblies can be made less subs
Flynn ,Thiel, Boutell & Tanis, P.C.
Mah Chuck Y.
Revvo Castor Company Limited
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