This afternoon I took a walk through the southern end of the BNSF’s yard here in my hometown, and in this yard there is an old scale house. It is very decrepid and looks like it has gone without a fresh coat of paint in 50 years or more. I know that the railroads used scale houses to determine the weight of a lot of what they were shipping; that was their bread and butter, so to speak.
Have scale houses pretty much fallen into disuse these days, are they a thing of the past? I looked in one of the windows of this one and I noted that the equipment used to weigh cars was manufactured by Fairbanks Morse, and probably belongs in a railroad museum.
I’m not really sure, but I don’t think that railroads set rates by weight any more. I believe that the charge is per carload. I’ve never seen an operational weight house, neither here in Germany, nor in the US, except at a grain elevator in Wamego, KS. Perhaps somebody could fill us in on whether or not commodities are still shipped at a rate per pound. On the other hand, considering the fact that lower track grades have weight restrictions, you would think that some means of weighing a car must still be used by the railroads.
The older style scale houses have pretty much gone by the wayside.These were somewhat complicated mechanical scales and Fairbanks-Morse was and is one of the larger manufacturer’s of scales. What you saw in the scalehouse was the indicator beam, much like the part on a Doctor’s office scale where you move the weights to get a balance on the beam then read the weight, but on a much larger scale (pun intended). The tracks in front of the scalehouse is where the mechanisim was (and maybe is), a series of levers (BIG castings) and pivot points that finally connect up to the indicator beam by a rod that should come up through the floor of the scalehouse. There may even be an entrance to the pit inside the scalehouse.
Modern scales use what is called a load cell in place of the lever system. This converts the deflection caused by the weight of the car to an electrical current and can be read on a digital indicator.
Tom, could you please explain how this works? Is the car not actually resting on a scale track? Does the mechanism use ultra-sound to determine density, then convert that into weight? I’d appreciate your help. Thanks!
Round our gaf they use strain gauges glued to the rail (just ordinary rail on ordinary ties in ordinary ballast). The wires from teh strain gauges go into a computer that works out the weight as the train passes. I saw a Danish system that uses accelerometers pretty much in the same way.
Load cells are just a piezoelectric thing (Google can help you), they can either be fitted between the rail and the tie or underneath it. THe days of having a seperate bit of track conneted to nothing but the weighbridge are long gone.
To add to what Hugh said, load cells are also much more compact. We had a 10 ton load cell on my last job. It was about 6 inches diameter by about 18 inches tall. This, of course, eliminates the pit needed for the lever mechanism on the older style scales. But that little SOB weighed about 60 pounds! You would just need a solid base to mount them, then put the scale rail on top of it.
railroads have “rolling” scales at most hump yards, getting weighed in motion going over the hill. They still need to know how much cars weigh so they can make sure how many horsee’s they need.