|January 30th 1977 was a bitter cold day. My shutter kept freezing! |
TV6 heads east departing Selkirk
Some FAQs, first.
What does it mean to have a "frozen locomotive"?
It means that the cooling water in the locomotive has frozen somewhere or worst case, everywhere. Since water expands as it freezes, this usually causes coolant leaks - bad ones - a myriad of ways. Pipes breaks. Radiators burst. Couplings "uncouple". Heads crack. Liners explode. Things like that.
Ever heard of anti-freeze?
Sure. Ever see what happens if you mix antifreeze with lube oil? Bearing destroying sludge is what happens. Locomotives, particularly EMD locomotives, often have slight water leaks. The leaks are pretty well tolerated as the water that makes it to the hot oil in the oil pan flashes into steam and is sucked out of the crankcase. The same slight leak with anti-freeze would ruin the crankshaft bearings in short order. Antifreeze doesn't boil off.
The other problem with antifreeze is that it doesn't cool as well as water which could lead to overheating under extreme conditions. This was not a deal-breaker, though.
How, exactly, does a running locomotive freeze?
Usually, the locomotive has to shut down to freeze, but in extreme cases, exposed water lines with low flow can freeze even when the locomotive is idling. Cab heater lines, parts of water-cooled air compressors and the engine intake air aftercoolers are most vulnerable.
So, why not just have a valve that drains the water before it has a chance to freeze?
Now, we're getting somewhere!
And, that's where this story begins.
By the time I came around, Conrail was installing two types of drain valve. An electrical solenoid valve which would open up provided the water in the line by the valve got near freezing AND the valve had power to it. Three problems. One, we didn't know if the spot we were measuring was the one that would get cold first. Would other stuff line cab heater lines or intercoolers freeze before the water dumped? Didn't know... Two, shut down locomotives often had their battery switch pulled, cutting off power to the drain valve. Did we really want to power it off the "wrong" side of the battery switch? Three, they were expensive! Several hundred dollars a pop - plus installation and wiring.
The second kind of valve was all mechanical. It took worked like a thermostat in your car. It had a small "power pill" made of beeswax and metal - or some such goo - that was formulated to melt or expand at a certain temperature. When it got cold, it would contract a lot and open the valve. There was only one problem with this valve. It didn't work! Oh, sure, when the water in the drain line got cold, the valve would start to open and some water would drip out, but as warmer water from the engine would trickle down, heat the power pill up and close the valve. The steady state was a slow drip, accumulating a few gallons over several hours and letting all sorts of freeze damage occur.
We needed to do some decent, instrumented testing. We needed to find out how fast different parts of the cooling system cooled and, knowing that, what kind of drain valve(s) arrangement might prevent freeze damage.
We didn't want to have to wait through another disastrous winter.
We needed to put a locomotive in a freezer in the summer.
Wait! What? Put a locomotive in a freezer? Really?
They have some pretty big freezers at Sears. Might be able to fit a 1:12 scale locomotive in one...
Fortunately, REALLY LARGE freezers exist. The Budd company's lab near Philadelphia still had their climate controlled chamber that they had used to to test and qualify the HVAC systems of passenger and transit equipment. It was for hire and it would fit a locomotive!
I wrote up a test plan and we grabbed a straight SD40 that still had hot water cab heat and fitted it out so that we could easily install any kind of drain valve and then wheeled in into Philadelphia and parked it in Budd's climate chamber. They set over 100 thermocouples following our direction and connected them to chart recorders. We were ready to start.
We installed an electric drain valve, started the locomotive up and let it idle until it was hot, then shut it down and turned on the huge bank of refrigeration units. The temperature started to drop. Within an hour or two, "pop" went the drain valve. Parts of the engine were still well over 100 degrees although the cab heater lines were perilously close to freezing, but overall, success. No freeze damage!
Next we fitted the mechanical valves including a pair in the cab heater lines under the walkway. Same routine. Hours later, in late afternoon, a small trickle from the cab heater lines. Then, a small trickle from the main valve. A hour or so later, it was obvious that this wasn't going to work. The air compressor was getting very close to freezing and we were afraid of freeze damage in other places, as well. We opened the big end doors and started up the engine to warm things up.
Bad news! We had some freeze damage in the cab heater lines and back by the air compressor. We shut down the locomotive and drained it all the way. It was about 8PM at this point and here's where I got myself in trouble.
I went home. I was thinking we'd fix things in the morning. Little did I know, the others stayed on to repair the freeze damage that night, finishing hours later. Maybe I didn't want to know? Boy, did I get chewed out the next morning!
After patching things up, we tried a mechanical valve that would snap all the way open and stay there. It worked about as well as the electrical valve, but was difficult to reset.
Then we tried a mechanical valve that sensed the air temperature near the valve inside the carbody. This valve reacted within an hour of shutdown and drained all the water - even the cab heater lines. To reset, you just grabbed the sensor with your hand to warm it.
Now, we were getting somewhere!
During one of the test runs, I got myself in trouble again. I got locked in the test chamber while the cooling system was running. The air was around zero degrees. I had a winter hat and coat, so I wasn't in any real danger of hypothermia. I climbed into the locomotive cab, thinking somebody would eventually wonder where I was and come get me.
But, given that I had "abandoned ship" earlier, maybe they didn't give it too much thought? Either way, after ten minutes or so, I decided to blow the horn - there was still plenty of air in the main reservoir - thinking they might hear it over the insulation and roar of cooling compressors.
They didn't. I tried again five minute later.
The good news was, they heard it. The bad news was it was because the same guy who chewed me out before was just coming through the access door and got an earful of horn at close range. This did not make him happy.
I got chewed out...again!
This time, I was pretty mad myself, since somebody locked the door to the room without knowing everyone was out. To this day, nobody has owned up to that "crime".
We made one more run with a modified air-sensing valve, insulated to allow some of the heat conducted from the piping to delay the opening a bit. We wanted to be sure that a running engine that happened to have a carbody door open wouldn't have too great a chance of accidently dumping the water.
Success! We went whole hog for these mechanical drain valves and freeze damage largely disappeared in subsequent winters.
Into the great, white north...
While the problem was generally licked, there continued to be a string of improvements made to the valve design. Each major iteration needed some level of testing to insure we were still well protected. Renting the test chamber and sequestering a locomotive for a period of time was out of the question, so we used "Nature's Test Chamber" - Selkirk NY. It got bitter cold there and was a fairly easy drive from Philadelphia.
We'd watch the weather forecast and them make a quick trip timed to coincide with the approaching cold front. We'd install the valve in the locomotive, apply a few well placed thermocouples and then move the locomotive outside for testing overnight.
The testing was fairly uneventful. One particular trip left a few memories. My car, a 1983 Escort GT, wouldn't start after we checked out of our hotel, so we had it towed to the shop, where it started immediately and nothing was found wrong. This was the begining of a chronic problem for that car solved only when Ford changed the material in the distributor cap.
|This car must have had some redeeming features, but mostly it was a lemon.|
The next day, the sun came out and the roads melted quickly and life returned to normal - except for the locomotives. No more winter locomotive-sicles!