In the fall of 2008, the six driving wheels for the Sierra #3 were transported to the Sacramento shops of the California State Railroad Museum. There they were reprofiled (surfaces were trimmmed smooth), journals turned and ground (the part where the bearing surface fits). The crankpins (the large cylindrical steel pieces that the rods connect to) were removed, the holes bored out, and the crankpin holes restored to “on quarter” dimensions. Quartering is an important process that corrects the stroke of the rods. The crankpins need to be exactly 90 degrees to each other, or they will work against each other (think of how it would be to pedal a bicycle if the pedals were not exactly 180 degrees opposite, and you get the general idea).
Today, the center driving wheels were returned to Railtown. Over the next few weeks, new crankpins will be machined in the shop, and inserted into the wheels.