One of the many items we have to restore, rehabilitate or replace are the driver tires for our Southern Pacific Railroad steam locomotive #1744. After removing the driving wheel sets from the locomotive’s frame over the past few months, we have now started and completed the process of removing the steel tires to allow for work on the driver centers and the eventual replacement of the tires.
Driver tires are designed to be replaced given they wear over time. Tires are interference fit on the driving centers which means the steel tire rings are actually smaller in diameter than the wheel centers. When heated, the expand enough to fit over the driver center and then when they cool, they shrink causing the interference fit. Occasionally shims are used to get a proper fit.
In our case, we need to first take off the old tires to allow for the driving centers and axles to be reworked before we install new tires. To do this, a propane gas “ring of fire” was constructed by our Steam Department volunteers to allow for even heating on just the outside of the tire during the process.
Our second challenge is that #1744 uses Stephenson valve gear. This type of steam locomotive valve control uses inner eccentrics attached to the center of one of the drivers. This makes it harder to deal with such a driver set since usually the plain axle center itself can be set on a stand to allow free access to the driving wheels themselves. With the eccentrics attached to the center of the axle, the alternative here was to stand the axle on end and allow gravity to aid in the removal of the tire.
Once in place, the ring of fire was lit and the removal process started; first allowing the tire to expand and be ‘helped’ off the driving center from some volunteer driven sledge hammers.
Here is a gallery of images that steps through the removal.
Cleaning beforehand… 
Cleaning beforehand… 
The fire is lit… 
Helping the process along… 
After what amounted to about 20 minutes of heating and persuasion from the sledge hammers, the tire dropped off. Mission accomplished! The other 5 have now been removed as well across the #1744’s three sets of drivers.
We want to take a moment to thank the Candelaria Fund for providing a $30,000 grant to us to purchase the new tires for the #1744. We still needs funds for the driving center and axle work. Would you please consider a donation today to help fund this critical work to ensure #1744 has solid running gear for many years to come?
Thanks and please look for more updates soon!