Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Casters – Bracket supports
Reexamination Certificate
1999-10-26
2001-12-11
Brittain, James R. (Department: 3626)
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Casters
Bracket supports
C016S01800R, C016S03500D
Reexamination Certificate
active
06327742
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to castors and more particularly to free floating castors.
The state of the art castors, as we are all aware, are wheels that trail the direction of motion of the platform or trolley onto which they are mounted. The wheel in the castor assembly has freedom to revolve, in the horizontal plane, around the vertical axis of the castor assembly, through 360°. The wheel being located at a certain distance (trail distance) from the single vertical axis of the assembly at the end of a trail arm makes the wheel follow the direction of the motion of the trolley.
Standard castors have two inherent flaws—one, the castors have a tendency to get wedged, and two, swiveling/fishtailing of the trolley onto which the castors are fitted when the direction of motion is reversed.
Wedging is a momentary restriction in the smooth motion of a castor trolley experienced during reversal of direction of its travel. While reversing the direction of motion, the castor becomes dynamically unstable. The wheel initially follows the reverse path and then deviates. During this process, the castors have to revolve to realign. The castors could either revolve in the same or opposite directions. Wedging occurs when both castors revolve either inwards or outwards, i.e., in opposite directions. During the reversal motion, the wheels get dragged momentarily until they realign. In order to overcome wedging, extra efforts needs to be applied which will be proportional to the weight on the wheels. This difficulty would, in day-to-day life, have been experienced while handling baggage trolleys at airports, etc.
Fishtailing of the trolley also occurs while reversing. Owing to the revolving action, the castors could revolve in the direction opposite to the intended one. For instance, while reversing the direction from forward to rearward, the castors could revolve in clockwise direction. Thereby, the trolley will swing towards the right hand side. In case of an obstruction ahead and in order to avoid it, one needs to apply additional force to turn left. However, on doing so, one finds a momentary resistance to the effort because the castors are revolving in the wrong direction. By continuing to pull backwards, one could hit the obstacle. The way out would be to push forward again, make the castors revolve in the opposite direction and then pull back or apply enough force to drag the wheels in the desired direction.
SUMMARY OF THE INVENTION
The present invention concerns an apparatus for improving the operation of castors by providing space for the wheel to move freely. The wheel thus can float freely within a fixed area. The principle of implementing the free floating castors can be done in two ways. One is by providing at least one shaft perpendicular to both the castor vertical axis and the wheel axle axis and thus making the wheel axle free to along the shaft between two stoppers/limits. The second principle is that of double rotary joints wherein an additional vertical rotary axis/joint is provided equidistant between the vertical axis and the center of the wheel. The additional rotary axis/joint enables the trail arm to revolve through 360° in the horizontal plane around it. In comparison to this, the standard castors have only one vertical axis.
The entire assembly can be fabricated according to any desired specification. There is no limit either to its size or weight carrying capacity. In terms of costs, the only added cost being that of shaft or rotary joint to a certain extent additional machining and fabrication charges.
Free floating castors find its usage and can be installed on all trolleys, equipment bodies, automated guided vehicles, etc. on which the standard castors are installed and on platforms/bodies on which the phenomenon of “wedging”/“fish-tailing” hitherto precluded installation/usage of castors. The free floating castor, according to the present invention, is easier in operation, allows free and better maneuverability thereby increasing its efficiency—enabling installation of the device on a wider range of platforms—and is cost effective, when compared with the state of the art castors.
REFERENCES:
patent: 1839396 (1932-01-01), Kimball
patent: 2073066 (1937-03-01), Kalberer
patent: 2170257 (1939-08-01), Andersen
patent: 3047904 (1962-08-01), MacDonald
patent: 3246908 (1966-04-01), Marvin
patent: 3758917 (1973-09-01), Schroer
patent: 4471508 (1984-09-01), Seaborg
patent: 5078221 (1992-01-01), Rewitzer
patent: 5996176 (1999-12-01), Ghouse
patent: 1805607 (1970-09-01), None
patent: 00-75802 (1984-04-01), None
patent: 406040202 (1994-02-01), None
patent: 409276337 (1997-10-01), None
Brittain James R.
MacMillan Sobanski & Todd LLC
Rodriguez Ruth C.
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