Shay Fire - Burner Tests
After the initial streaming test on December 3, 2003 many deficiencies were corrected and then additional tests were conducted in December and January that revealed several additional problems described here. More corrections were made when everything was disassembled for painting. Then additional tests were conducted in April which revealed a few more problems that were quickly repaired. Finally, on April 21st the burner was test again and seemed to run great ---- this thing is ready for the track.
Note that I've described the winding path I've taken to get this burner working properly for several reasons. One reason is encourage folks to keep at it when building a live steam locomotive ---- things often don't work perfectly the first time. A second reason is that maybe you all can develop a feel for how the burner should run from my experience. While writing this summary, I realized that I didn't know how a proper burner should operate since I'd never operated one ---- sort of like a hunting elephants when you've never seen an elephant. I've summarized the operation of the burner at the end to tie everything together.
January 29th Test: Between December 16th and this test on January 29th the cab roof, whistle and steam powered pump were fabricated and installed. The snow was deeper on the 29th as seen in the photo above and it was pretty cold ---- about 15 degrees. Mark Mihalyi had come over from near Pittsburgh and we both froze.
Two 5/8" vent holes had been added to the rear of the fire pan and that seem to fix the burner --- it was very reliable. The pump and the modified brakes with both steam powered application and release all worked great. The whistle however didn't work very well ---- too cold --- the steam condensed and it spit more than it whistled. Hopefully it'll work better in warmer weather. The only other problem noticed was that the blower seemed to be less effective than on previous tests. Several of the blower holes were found to be plugged when it was later disassembled for painting. The engine had been run quite a bit on compressed air and the lubricator was supplying too much oil, much of which ended up on the blower It was probably this excess oil that plugged the blower holes.
This test was cut short after about an hour when one of the water pipes froze. Were were glad to get inside and warm up.
April 15 test: April 15 is a day I normally dread as I wait to mail my income tax payment while grumbling about it all day. This year I was due a refund so it was mailed in early February. The refund arrived weeks ago and has already been used to stimulate the economy. The day was bright and sunny so I spent all morning and most the afternoon cleaning up limbs and other debris from her lawn. It'll take another few hours before the lawn is clear enough to run the mower. (She's already fertilized it ---- I keep hoping she applies Roundup by mistake.) Anyway, by about 4 pm I was exhausted, sore and not in a good mood ---- like a normal April 15th.
Wheeled the shay out on the walkway, put some diesel in the fuel tank and filled the tender. Connected the compressed and used the steam powered pump to fill the boiler. Just when I got it to the correct level, the pump quit. Drats!
I tried to light the burner with the igniter --- not luck. It lit easily with the propane torch. After it ran for a few minutes, I shut off the atomizer air valve to extinguish the flame and then turned it back on. The igniter easily relit the burner. At least that part worked slick. Through that test I used the igniter several dozen times and it worked every time. The igniter can be labeled finished!
Tested a number of variations of throttle opening and fuel, atomizer and blower settings. The atomizer seemed to run fine at 8 to 10 psi. The burner seemed to produce the best heat with 25 psi or greater blower when engine is not running.. When running, the exhaust creates a draft so the blower can be cut back. It looks like leaving the blower on about 10 psi when running will keep the burner running if the throttle is closed.
There were several problems uncovered:
Fuel Flow: The nozzle was checked and verified to be clear. Next, the flow at the output of the filter was checked. The flow didn't increase after the valve was opened about 1/2 turn. There was only about 1 inch of fuel left in the tank. I filled up the tank and opened the valve again. There was much greater flow when the valve was opened. This indicated there may be a problem with very low fuel level.
April 17th Test: Fired it up again on April 17th. The good news was that the burner worked much better --- greatly reduced heat around the back of the boiler (I was beginning to wonder if I really wanted foot pegs ---- it looked too hot down there). The larger rear fire pan vent worked better, could keep the fire going at full throttle with door closed. Also noticed better fuel control and could make it smoke a little with a rich flame. Also noticed a relationship between the amount of blower, smoke and fuel setting ---- i.e., increased fuel caused white smoke, increased blower leaned it out and it stopped smoking. This was all as I initially expected. Another piece of good news --- the lubricator wasn't bubbling oil.
This test was for about an hour. Whistle worked great --- recall that it just spit in freezing weather. There were a few small steam leaks but I'm getting used to them --- that might be easier than actually stopping the leaks. The Teflon packing in the engine rod and valve stem glands worked really great. I did notice that the rod bearing on the rear cylinder is a little loose. Maybe I can mill the joint between the two halves slightly and then ream it again. After I shut everything down again I noticed bubbles on the lubricator vent again. Even so, it was a good day.
The Lubricator Again: This time I cleaned the lubricator up before working on it. What a mess!!!! The steam that backed up through the lubricator tank turned the steam oil into a thick sticky grease --- it must have washed out the tallow. I couldn't see anything wrong with the ball check valve but did see some small pieces of copper from the end of the output pipe I cut off last time. That might have been holding the ball off the seat. Also, maybe it was just the grease left from the last time steam got into the tank ---- I didn't clean it out that time. I did drill out the seat slightly to (hopefully) make a better sealing seat. I later tested it running the engine on compressed air. First, the output was left open at the union next to the steam input header to verify that it pumped oil to that point. The union was then connected and engine run for about 20 minutes; no bubbling from the lubricator. (Note: I had further trouble with the lubricator and later changed the design to use a poppet check valve. This change is documented on the Lubricator page.
April 21 Test: The locomotive was fired up again on the test stand to check the operation with the new filter. The operation finally seemed correct. Some of the key points were:
The locomotive is ready for a test at the track.
April 28: Took it to the track today and it ran pretty for about 90 minutes and then a few problems developed. This first operation will be discussed in the operation section. The burner modifications described here seemed to work well.