what size/steel grade rail for my inline measuring gauge?

[aweeks5]

I'm looking to order twin straight steel ground rails for a mobile gauge weighing around 10000 lbs that will be able to move in and out of our production line. The gauge is to be on 4 wheels and I was thinking of ordering 2" square rails around 20 feet long to place in or on our concrete base, but wasn't sure if I needed to worry about the material or get a larger size rail to support such high weight. Any structural or mechanical or materials engineers out there who can point me in the right direction? Thanks in advance.

 

[MikeHalloran]

You may need to use cold rolled steel instead of hot rolled steel for the rails, or even buy actual train or crane rails, which are quite hard on top.
See, e.g., birminghamrail.com , from whom I have bought a few miles of crane rail.

You may also need to use wheels larger than you have imagined, in order to limit the contact stresses for a reasonable life. Guys who sell crane wheels should be able to help you with that.

... unless you really need precision rails, to minimize trajectory errors.
For a while at least, a long time ago, GM had their machine tools built with ball bushings running on precision ground hardened rods about 100mm diameter. I have no idea what GM uses now, but that's another area to investigate.



Mike Halloran
Pembroke Pines, FL, USA