Crane Rail Loading

[LSPSCAT]

Does anyone have a reference or derivation for basic allowable crane rail loadings?

Whiting Crane Handbook (p. 66,67)provides:

P = (A) X D X W

A = Varies between 1600, 1400, 1200

Manufacturers also list this value as a function of the Brinell Hardness.

D = Diameter of the wheel
W = effective rail head width

I am basically looking for the derivation of A? Is it empirical or based on the hertzian contact stress?

 

[dhengr]

LSPSCAT:
I would be surprised if you could find a derivation for “A.” Maybe some historical search would lead you to how these numbers where arrived at. I would go to WHITING engineering directly. The AAR has done much work on this subject as relates to wheels and rail on railroads. I suspect they are some sort of an empirical value based on WHITING’s, or industry, experience and standards. Note that your 12, 14 & 1600 values are based on wheel tread treatment for wheels of rolled steel material, and finally the crane usage classification. These are all considerations which would go into arriving at a FofS value, and a working wheel load value. And, of course the Brinell hardness is a good indicator of the ultimate strength of the steel in the wheel or the rail in the regions (surface depths) of the contact stresses in question. YES, this is a Hertz stress problem, with one dia. being the wheel dia. and the rail having an infinite dia. (a flat surface). My WHITING book is a 1967ed., pgs. 66 & 67 show what you cite, so I would guess there is more current industry info. and stds. out there and you should get your hands on that. Your problem is picking a FofS, probably an industry std. as a function of crane usage class; knowing the material properties of the wheels and rail and their hardness (and its depth) so you have an Fult. or Fy; and knowing the mating shapes of the rail head and wheel, so you can make a judgement of the deformed bearing surface shape, probably elliptical.

 

[LSPSCAT]

dhengr,

I have several questions out to various rail manufacturers to get information because most of them still have an empirical value in their published literature(current technical publications). We have worked out the hertzian stress problem several times for various rail and wheel combinations and associated Brinell Hardness. Mainly just trying to see what the original calculations were based on. Thanks for the input, the application is navigation and dam lock gates so slightly unique in terms of materials and usage. Historically we have deferred to these values without issue and noone has ever raised the question. It seems that calling around nobody has a quick answer either. I have multiplied so many different combinations of numbers together I am going to be dumbfounded when I finally see what was done!!

 

[RolMec]

Hello LSPSCAT,

if you can lay your hands on a german DIN 15070 standard, there's some guidance in it. If not, FEM 1.001 cranes is some minimum "state of the art" design guide. That's how it works quick. Also, these are accepted design basics just for the day when you have to produce the paperwork.
If you want to know ?why?, you'll have to dig deep, there's so much "testing" and "experience" and "experimental" factors in it. imo (A) is multidim from static hertz contact pressure, rolling contact geometry / material & fatigue considerations.

R