There has been a lot of speculation on the cause of the piston failure on SP 18 on April 9 during the Cascade Canyon trip on this forum and many others. I was riding the train in the open car as we were climbing the hill out of Hermosa toward Rockwood. The locomotive was running very well as we approached the highway 550 overpass. There was a loud bang that was audible on the open car at the rear of the train then a quick stop. The locomotive had been pulling up the 2.5% grade with the 4 car train. She was not working water and the stack was a light grey. There was a very experienced engine crew on the locomotive. When we stopped the train crew did a great job addressing passenger safety, getting information to the passengers about what happened and keeping the passengers informed about what was happening next.
As Olaf's photos show the piston and piston rings from the right side ended up in a lot of pieces. It was clear from looking at the broken parts some piece of debris between the piston rod and the head punched out the hole in the head. There were small marks on the punched out part of the head. Larry Beam and Randy Babcock were on site within a few minutes and pulled the head and all the broken parts they could remove out of the cylinder. One large piston part was pushed back in the cylinder and wedged into place for the slow reverse move to Pinkerton siding with the diesel from Rockwood. The D&S RR's new Superintendent walked through the train prior to our departure from the breakdown site and explained what they thought had happened and apologized for the breakdown. The D&S team handled a very difficult situation in a very professional way.
Anytime we get these operating antiques out and use them as they were designed to be used there is a risk that we will break something. Even with that risk, I would rather see a steam locomotive operate than be stuffed and mounted rotting away in a park or a museum. The crew that restored SP 18 includes several members of the D&S staff. I am confident they will fabricate the new parts to get her operating again soon. SP 18 had not been operating for many miles yet, chalk this up to an early restoration problem that may have been a hidden flaw in the piston from her SP days or a material defect in one of the new rings. We will probably never know the root cause of the initial failure due to the damaage done to the parts as the train came to a stop. From what I understand, the D&S staff have a good understanding of the general sequence of events that occurred with this piston failure and how to prevent a reoccurrence.
Many thanks to the team that got SP 18 out of the park and to the D&S staff that brought us the opportunity to ride behind this locomotive. I am confident we will have another opportunity to see SP 18 operate on the D&S before she heads back to California.
Scott Gibbs
315 Deputy CMO
retired mechanical and metallurgical engineer
