Would changing the spring force on driver axles adjust the load on each driver?
On class 8 spread-axle flatbed trailers the pressure in the suspension air bags is altered to keep axle loads the same.
Just thinking…
-Kevin
Here’s a drawing showing some of the elements of springing and equalizing on a steam locomotive:
You can follow the linkage down the row to see the equalizing action. Push up at one location, and everything moves to keep the wheels on the rails.
As to your question, the “bolts” going through the holes in the ends of the springs have nuts to lock onto those springs. And they can be moved. Hence the spring force on an axle can be changed. Of course, the leaves can be changed out, too. If the equalizing arrangement is designed to not include some or all of the adjusters, one is left with doing it only with spring changes.
“All” steam locomotives in the US used a three point suspension. In the case of an 0-6-0, the front axle would NOT be equalized to the others. It would be sprung however. This would provide the forward central support for the locomotive. The other two axles would have equalization on each side. That would provide the two rear supports for the locomotive.
You had essentially a tripod, with the rear two legs going directly to the rails, and the front to a loose pivot.
A 4-4-0 is perhaps the simplest to envision. The drivers have, on each side, a simple equalizing bar above/below each of the two journal boxes. That creates the rear legs of the tripod. The front truck pivots about a center pin. That’s the front leg.
Ed
Increasing polar moment of inertia might improve issues with reciprocating augment on an engine with no lead truck…
Mr. Meador here gives a very informative walk around explaining some frame and steam chest design criteria for the PRR 1361 in Altoona:
A very worthwhile seven-and-a-half minutes.
Regards, Ed
Time well spent indeed.
Thank you for posting the video. There sure is a lot to a steam locomotive frame.
-Kevin
I’m really glad I asked the question about sand domes on the USRA 0-6-0’s! Thanks for the HELP!
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