For someone with a very limited knowledge of steam, a couple of questions: Would this engine have been equipped with a mechanical lubricator when built? If a locomotive is equipped with a mechanical lubricator, do you just assume oil is getting to everything and refrain from manually oiling? I would guess that you don't want to give a locomotive an "oil bath", which would be unsightly and cause dirt to cake, but do you oil things like cylinders again "just to be sure"?

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The one time I've seen this happen, the hole in the head was caused by the end of the piston rod striking the head at its center...
In that case, it was a Hiesler locomotive....so a bit different, but the rod big end separated at the crank shaft....this happened while working pretty hard...and the piston assembly shot upward and struck the head....it was quite exciting and loud...accompanied by flying parts and bits.....and a large cloud of steam...
Anyway, the end result looked nearly identical...a hole in the center, with a number of cracks radiating from it....although, I never did see the piston later on, so not sure if it was shattered too....

Lack of lube would overheat the rings causing them to collapse and leak steam around their circumference first (not to mention the shrieking). This would be very noticeable when in operation. I do sort of see how a piece of ring caught in a port could present problems, except the ports are at the very extremeties of the bore. There must be something more to the story......

Being that 18 is a slide valve engine, the very first indication of a lack of lubrication would be the Johnson Bar racking violently in the quadrant. Trying to move the Johnson Bar in this situation would likely send you out the front door of the cab. This would happen long before piston damage would occur.

The lead mechanic along with several other mechanics pulled the cylinder head and removed the shattered piston so we could put the #18 into the siding. It was the Superintendent who told us that the locomotive broke down because the lubricator was not working. Considering they have seven operational steam locomotives, and have been running a steam program probably longer than anyone. It's safe to say they know what they are talking about. I will believe them on any steam related issue before I listen to anyone on these or any other forums.

I have extensive engine rebuild experience with both gasoline and diesel engines. When I looked inside the cylinder the walls I was shocked to see there was no damage. No nicks, no gouges, hardly any scratches. The cylinder head showed only a small nick (with the exception of the blown out middle section). Hardly what you would expect had something broken off and was getting pounded hundreds of times a minute.

I believe what happened is the cylinder ran out of oil, the piston locked up, and the piston rod pushed right through the sized piston. In the process a piece of the top piston fell in front of the piston rod and that is what punched out the middle portion of the cylinder head. You can't tell from the photos but the piston is no longer attached to the piston rod. The rod is simply moving back and forth with the broken piston underneath it. That is why the cylinder showed really no damage along with the cylinder head. That is also why the broken pieces are not all smashed together at the front of the cylinder. The piston sized, shattered, and the broken pieces fell in front of it.

Had the piston ring broken as some had said. Then you would either have a section of the piston broken off or the entire piston broken off from the piston rod. Considering that the steam ports are at either end of the cylinder, if the piston broke off from the piston rod it would be at either the front of the rear of the cylinder. Not in the middle. Had just a section of the piston broken off it would show considerable damage to the cylinder head. I also don't believe the piston ring would be capable of breaking that piston which was at least two inches thick. Piston rings are brittle or in the case of some steam locomotives brass. Neither one is going to hold up very well when sheared.

As far as the #18 goes I was surprised how worn out it was. While trying to remove a large portion of the broken cylinder using a pry bar. The cross head was moving up and down with what seemed like inches of free play. The steam pipe from the dynamo was wobbling around looking like it might fall off. Earlier in the trip we stopped for water. The water tank was empty so we backed up to a creek that had so much muddy water it was dark brown in color. I couldn't believe they put that nasty muddy water into the tender.

I do have video including when the piston broke as we were traveling which made some pretty interesting sounds. When I am done editing I will let you know.

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Interesting - there would need to be a LOT of lost motion in everything from the crankpin forward through the main rod and crosshead to allow the rod to keep moving beyond the stroke and clearance to knock the head through at the center - so much that it would have decidedly been noticeable before reaching critical mass. I think a lot of us have had locomotives in service with rings we didn't know were broken until we did a tear down also..... to find out where all the steam was going instead of moving the train and the source of that whooshing noise. West Side Shay 14 had a cylinder - the rear - that had lost its clearance in a wreck at some point and the center of the head had been bored deeper into the casting to clear - we had to be VERY careful when setting up and adjusting the rod coming off that crosshead. Poor old girl.

Things that I found of interest on this locomotive were that the cylinder head was clearly not a BLW original, but a replacement. Not sure if the originals were lost or destroyed in the 18's past. Secondly, it would seem that the piston that exploded was also some sort of aftermarket model and not what it would have had from BLW. A piston of that size from BLW would have had 3 cores and 6 ribs. As Kelly so graciously pointed out, that piston seemingly had none.

The failure zone as it appears to me on the piston occurred right at the stress riser in the bottom corner of the ring grove. I wonder if the piston was working on the rod and finally reached a point where it had enough momentum to punch itself through the piston? Increased resistance from lack of lubrication between the packing rings and cylinder wall would amplify those working forces if that was the case. If not, then I wonder if simply the increased resistance at the rings was enough to open up a crack at the bottom of the ring groove and allowed it to propagate until ultimate failure? I don't know for sure, just speculating and throwing ideas out for what their worth.

Jeff

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So if a lack of lubrication did not cause it what did. You seem to be saying valve oil is unessary.

Robby Peartree

Kelly - thanks for posting the video link. I have a few questions about this:

1. Had the engineer closed the throttle valve by the time the cylinder head cover, along with a portion of the cylinder head, were blown off (or punched out)? If not, then why does it appear in the video that no steam is coming out of the opening in the cylinder head? Could something have been preventing the steam from getting to the cylinder? A wet engine may be able to run without lube but it seems that the piston will seize without steam
2. It has been mentioned that the consist was backed up so that the tender could be refilled at a creek. Was a regularly scheduled watering overlooked or was the locomotive consuming a lot more water than anticipatedd? If the latter, could the excess water consumption have been an early indicator that the piston and/or piston rings had already started to fail?

Sounds like the engineer shut the throttle the moment 18 started to self destruct, which is why there is no steam blowing.

Like all slide valve soaks, #18 gets her valve oil thru the top of the valve chest cover. There is no separate oil line to the cylinders like on a superheated engine. So once again, I state if the there was no oil getting to the right side, the valve would have run dry and the reverse lever would have begun the rack very hard back and forth in the quadrant. That would be the first indication of lack of lubrication.

If the valve gear was behaving, then all hell broke loose, something else was the cause.

Hermosa is a regular water stop for small engines working the Silverton branch.

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