endtruck design for underrunning bridge crane

huangyhg

endtruck design for underrunning bridge crane
i'm thinking of a design for an underrunning endtruck, and wondering why i haven't seen it in commerical cranes.  basically, take a standard rigid dual-c-channel endtruck and replace the fixed u-channel endcap with a tie-rod (with bushing on each end):
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   (end view)
the tie rod would keep the wheel spacing fixed, but would allow small vertical wheel movements, giving a crude suspension. this would make the wheel loads more uniform, allowing smaller runways.  but it wouldn't introduce all the other degrees of freedom that the flexible (carriage style) endtrucks have.  
wondering if it has been tried.  drawbacks?
thanks, david
david
you must be new to the crane design. your suggestion is
approximately 40 years old. yes ,many companies used and use channel endtrucks. because of the limitation the trend is to use trolleys on both end. this gives a greater flexibility and load distribution. your idea sound simple but in the reality is not so. there are many forces which have to be taken in to consideration. yes, weak channel will help for load distribution to all wheels but how about
the other forces. you need a quit strong connecting rod , and this cancels out the flexibility.
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