Switcher track and sled

Abstract

A switcher track apparatus comprising four switch units having precisely supported turntables at the intersections of the rails of two tracks, with switch sections of the track on the turntables movable into alternate switching positions in alignment with the two tracks and with magnet assemblies for establishing and releasably holding precise alignment. A dolly or sled for riding on the tracks has four wheel assemblies at its corners each comprising two rows of four roller wheels in a V-shaped arrangement for engagement with curved rail surfaces. The wheel assemblies are carried on sprockets that are tied to a driver sprocket on a T-bar for operation in unison.

We claim as our invention:  
     
         1 . A switcher track assembly for use with two intersecting tracks having parallel rails and a sled having four wheel assemblies for riding on the tracks, comprising: 
 four switch units positionable at the intersections of said rails to lie under the wheel assemblies of the sled that is positioned over said intersections;    each of said switch units having a rotary turntable with a switching rail section movable between alternate positions aligned with the respective tracks;    and magnet elements in said switch units oriented and positioned to move the switching rail sections into alignment with the respective tracks when the turntables are close to such alignment, and to maintain the switching rail sections releasably in precise alignment with the tracks.    
     
     
         2 . A switcher track assembly as defined in  claim 1  wherein each of said switch units comprises a generally circular base having four stub rail sections spaced ninety degrees apart and extending radially outwardly for connection to said parallel rails of the intersecting tracks, and said turntables are circular and disposed over said bases with said switching rail sections alignable alternately with different switching rail sections.  
     
     
         3 . A switcher track assembly as defined in  claim 2  wherein said magnet elements comprise at least one first permanent magnet mounted on each of said bases beneath the turntable thereof and at least one second magnet element mounted in the turntable above the base.  
     
     
         4 . A switcher track assembly as defined in  claim 3  wherein two of said first permanent magnets are recessed in recesses in said base, and a plurality of said second magnet elements are recessed in said turntable.  
     
     
         5 . A switcher track assembly as defined in  claim 1  further including a sled having four wheel assemblies for riding on the tracks and being positioned on said switcher units to be switched from one of the tracks to another, each of said wheel assemblies comprising a plurality of roller wheels disposed in two rows of wheels rotatably mounted on a carrier on said sled, said carrier being rotatably supported on the sled for turning of the wheel assembly into alignment alternately with the rails of the two tracks.  
     
     
         6 . A switcher track assembly as defined in  claim 5  wherein each wheel assembly comprises two rows of four wheels each, mounted on said carrier for rotation about axes that are angularly spaced so that the two rows of wheels define an elongated V-shaped groove for engagement with the rails.  
     
     
         7 . A switcher track assembly as defined in  claim 6  wherein said axes are spaced about ninety degrees apart.  
     
     
         8 . A switcher track assembly as defined in  claim 5  further including a chain-and-sprocket positioning mechanism for the wheel assemblies comprising a driver sprocket and four driven sprockets at the corners of said sled, an operator on the sled for turning the driver sprocket, and an endless chain connecting the sprockets for movement in unison, the driven sprockets having shafts supporting the wheel assemblies on the sled.  
     
     
         9 . A sled for use with a switcher track assembly having switch units at the intersections of the rails of two intersecting tracks, said sled comprising: 
 a rectangular body forming a platform for carrying a load along the tracks; and    four wheel assemblies beneath the platform for riding on the tracks and to be positioned on the switch units at the intersections to be switched from one of the tracks to another;    each of said wheel assemblies comprising a plurality of roller wheels rotatably mounted on a carrier on said sled, said carrier being rotatably supported on the sled for turning of the wheel assembly into alignment alternately with the rails of the two tracks.    
     
     
         10 . A sled as defined in  claim 9  wherein each wheel assembly comprises two rows of four wheels each, mounted on said carrier for rotation about axes that are angularly spaced so that the two rows of wheels define an elongated V-shaped groove for engagement with the rails.  
     
     
         11 . A sled as defined in  claim 10  wherein said axes are spaced about ninety degrees apart.  
     
     
         12 . A sled as defined in  claim 9  further including a chain-and-sprocket positioning mechanism for the wheel assemblies comprising a driver sprocket and four driven sprockets at the corners of said sled, an operator on the sled for turning the driver sprocket, and an endless chain connecting the sprockets for movement in unison, the driven sprockets having shafts supporting the wheel assemblies on the sled.