Floating castors that stop trolleys from fishtailing
Free floating castors includes a casters system assembly mounted to move relative to a vertical axis of rotation at which it is attached to a trolley to provide space for the casters system to move freely within a fixed area. At least one shaft extends perpendicular to the vertical axis of rotation and the axis of rotation of the casters system on its axle. A bearing permits movement of the axle along the shaft in between two limits. In a second embodiment, a rotary joint assembly is connected between the vertical axis of rotation and the casters system to permit the casters system to revolve through 360° around a vertical axis of the rotary joint assembly.
1. A castors apparatus for attachment to a trolley comprising:
a bearing for attachment to a trolley and having a generally vertically extending castors vertical axis;
a bracket assembly retained by said bearing and rotatable about said castors vertical axis, said bracket assembly including at least one generally horizontally extending shaft having a stop at either end thereof;
at least one casters system rotatably mounted on an axle for engaging and rolling along a surface; and
a mounting means attached to said axle and engaging said shaft for permitting free movement of said casters system and said axle in a generally horizontal plane along said shaft between both said stops transverse to said castors vertical axis within a predetermined area surrounding said castors vertical axis, said mounting means including at least one pulley attached to said axle and having a peripheral groove engaging said shaft, whereby when said bearing is attached to a trolley, said casters system and said axle trail said castors vertical axis along a path of travel of the trolley and said casters system is prevented from wedging and/or fishtailing upon reversal of a direction of the trolley along the path of travel.
2. The castors apparatus wherein said bracket assembly includes another generally horizontally extending shaft, both shafts being positioned on opposite sides of said casters system, said mounting means engaging each of said shafts for permitting the free movement of said casters system.
3. The castors apparatus including another casters system rotatably mounted on said axle for engaging and rolling along a ground surface; said shaft being positioned between both casters systems.
4. The castors apparatus wherein said mounting means includes at least one roller attached to said axle and engaging said shaft.
5. The castors apparatus wherein said shaft is an upper shaft and including a lower shaft extending generally parallel to and below said upper shaft between both stops, said mounting means engaging said upper shaft when said casters system is resting on a surface and engaging said lower shaft only when said casters system is lifted away from the surface.
6. The castors apparatus including another casters system rotatably mounted on an axle for engaging and rolling along a ground surface; another shaft extending generally parallel to said at least one shaft, generally horizontal extending both shafts being positioned between said casters systems, and a generally “T” shaped housing attached to said axle between both casters systems and both shafts, and one of a roller and a linear bushing attached to said housing and engaging both shafts to attach both casters systems to said bracket assembly.
7. The castors apparatus wherein said shaft is one of circular or square in cross section.
8. A castors apparatus for attachment to a trolley comprising:
a bearing adapted to be attached to a trolley and having a generally vertically extending castors vertical axis;
a bracket assembly retained by said bearing and rotatable about said castors vertical axis, said bracket assembly including at least one generally horizontally extending shaft;
at least one casters system assembly rotatably mounted on an axle for engaging and rolling along a ground surface;
a mounting means attached to said axle and engaging said shaft for permitting free movement of said casters system transverse to said castors vertical axis within a predetermined area surrounding said castors vertical axis whereby when said bearing is attached to a trolley, said casters system trails said castors vertical long a path of travel of the trolley and said casters system is prevented from wedging and/or fishtailing upon reversal of a direction of the trolley along the path of travel along of travel; and
another casters system rotatably mounted on an axle for engaging and rolling along a ground surface, another shaft extending generally parallel to said one shaft, both shafts being positioned between both casters systems, and a generally “T” shaped housing attached to said axle to said housing and engaging both shafts to attach both casters systems to said bracket assembly.
9. The castors apparatus wherein said bracket assembly includes another generally horizontally extending shaft, said shafts being positioned on opposite sides of said casters system, said mounting means engaging each of said shafts for permitting the free movement of said casters system.
10. The castors apparatus wherein each said mounting means includes at least one of a pulley, a roller or a pinion engaging said shaft.
11. The castors apparatus wherein said bracket assembly includes means coupling said casters system and axle to said bracket assembly.
12. A castors apparatus for attachments to a trolley comprising:
a bearing for attachment to a trolley and having a generally vertical extending castors vertical axis;
a bracket assembly retained by said bearing and rotatable about said castors vertical axis, said bracket assembly including a generally horizontally extending upper shaft having a stop at either thereof and a lower shaft extending generally parallel to and below said upper shaft;
at least one casters system rotatably mounted on an axle for engaging and rolling along a surface; and
a mounting means attached to said axle and engaging said shafts for permitting free movement of said casters system and said axle generally horizontal plane along said upper shaft between both stops transverse to said castors vertical axis within a predetermined area surrounding said castors vertical axis whereby when said bearing is attached to a trolley, said casters system and said axle trail said castors vertical axis along a path of travel of the trolley and said casters system is prevented from wedging and/or fishtailing upon reversal of a direction of the trolley along the path of travel.
Description
BACKGROUND
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 casters systems that trail the direction of motion of the platform or trolley onto which they are mounted. The casters system in the castors assembly has freedom to revolve, in the horizontal plane, around the vertical axis of the castors assembly, through 360°. The casters system 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 casters system 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 castors trolley experienced during reversal of direction of its travel. While reversing the direction of motion, the castors becomes dynamically unstable. The casters system 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 casters systems 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 casters systems. 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 casters systems in the desired direction.
SUMMARY
The present invention concerns an apparatus for improving the operation of castors by providing space for the casters system to move freely. The casters system 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 castors vertical axis and the casters system axle axis and thus making the casters system 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 casters system. 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 castors, 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.