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[prezmxkx]

I know that there are cars that are used to test the scales used to weigh cars.  How are the weight of the cars used to set the scales determined?  Is there a scale that is used as the standard to measure these standard cars?

[DSchmitt]

Found here:    http://www.railroadforums.com/forum/showthread.php?34661-Scale-test-car 

"The USDA Scale Test Car is used by the Class I's to calibrate/validate their individual scale test car calibrating systems.
The Class I's all have Scale Test Car calibrating scales that are not the same as the Weigh-In-Motion scales along line of road or the various hump scales, and are used to calibrate each scale test car periodically.
These specific calibrating scales each get a visit periodically by the USDA Scale Test Car.
In essence, the USDA car is the Master and is used to assure that the calibrating scales, (not the weigh-in-motion or hump scales),  are accurate.
It's markings are FGWX 300000 and pix are easily found on the net."

 

Some info about FGWX 3000000

http://www.krunk.org/~joeshaw/pics/pvt-box/fgwx/

 

 Found this AAR document dated June 3, 2011:

https://www.railinc.com/rportal/alf_docs/Circulars/OT-41.pdf

 

 

 

Link site to pdf copies of various OT Circulars:

https://www.railinc.com/rportal/aar-circulars

 

 

 

Reports of the Department of Commerce 1913-1920 has a discussion about track scales and test cars. It is a free download from Google Books:

 

http://books.google.com/books?id=Za4yAQAAMAAJ&pg=PA267&lpg=PA267&dq=railroad+scale+test+car+calibration&source=bl&ots=4j_3n0ELAr&sig=GwXlPZB_9IOBWQzSMnCJ7X5-iGo&hl=en&sa=X&ei=cZ1cUo36I4WG2wXLmoDwBw&ved=0CFMQ6AEwBDgK#v=onepage&q=railroad%20scale%20test%20car%20calibration&f=false

[Deggesty]

Thanks, DSCHMITT. I have known of the existence of scale tracks and the rules for using them, and the existence of the cars owned by the railroads and the care taken in transporting them, but had seen nothing as to the checking of the calibration of the cars.

A question: how is the Master Car's calibration checked? Is it simply that the owners possess a set of standard weights which are used? Call me lazy if you will, but when I began searching, I was almost overwhelmed by the quantity of listings of "Railroad scale calibration." Perhaps you know of a more precise address which gives details on this process.

[DSchmitt]

From the Dept. of Commerce Reports page 266.  Probably use similar method today.:

 

  

[BaltACD]

Balance beam scales are rapidly becoming things of the past.  Most all weighing on today's railroads is done with weighing in motion scale systems.  Weigh in motion scales are periodically checked for accuracy.