Lightweight Bridge Crane - beam loading question

[RedNeckRacin]

you need to top mount the bridge and not roll down the web flange. Otherwise you are going to get into some interesting buckling issues.

 

[dfkrug]

you need to top mount the bridge and not roll down the
web flange. Otherwise you are going to get into some interesting buckling issues.

I agree that a top-riding trolley would allow smaller-section beams in that area. Constraining
the trolley would be a different design, of course. The OP has already chosen a tapered-wheel trolley
as noted in post #3 above. Said another way, designing for a flange-hanging trolley just
requires bigger steel.

It is easy to over-design for low stress areas, too. A 4-post frame does not need one-inch
thick base plates, for example.

 

[RedNeckRacin]

I agree that a top-riding trolley would allow smaller-section beams in that area. Constraining
the trolley would be a different design, of course. The OP has already chosen a tapered-wheel trolley
as noted in post #3 above. Said another way, designing for a flange-hanging trolley just
requires bigger steel.

It is easy to over-design for low stress areas, too. A 4-post frame does not need one-inch
thick base plates, for example.

Maybe I need to clarify, I think the underslung trolley is fine. The rails that the bridge is riding on need to be underneath or above the bridge. Running them down the flange between the webs of the outside rails is going to cause some confinement and twisting issues running on the flanges.

 

[LD1]

Agree, either run the crane on top, on a rail. Or completely under but riding on BOTH flanges of each beam.

I-beams have very low torsional strength. And all the weight being on the inside two flanges....not a good setup.

I went top running on mine. Two reasons....I had 40# rail that was free. And because I wanted maximum head room. My side beams that have the rails are along the wall...who cares if they have less head room. If I were to make them TALLER, and run my 18" beam UNDER them instead of on top, I would have lost head room in the working area of my shop.