I saw a video on YouTube Where a locomotive (It looked like an SD40 something.) Was blistering along at about 15mph when a puff of smoke and some sparks came out of the DNBK blisters. Then, a disk looking thing went flying about 35 feet in the air and landed next to the train. The train passes the camera sparking, and smoking very lightly. Surprisingly the train just kept on rolling. (One of the comments said “That’s UP safety standards for you!”) What really happened here? What does each situation look like?
Blown turbos aren’t all that uncommon. Here’s another clip of a Pan Am Railways train doing the same thing. (Skip to 4:02) I believe the unit was out of service for a week while they put a new turbo in.
I am curious too because I was never sure it was properly explained what happened in your first vidoe. I tend to think it was not a turbocharger explosion. Turbo disintegration leads to excessive smoke because the engine is suddenly starved for air compared to the amount of fuel being injected.
Isn’t that frisbee-looking object a fan flange or ring. It appears as if the fan lifted off and took the ring and wire grill with it. But why would the fan launch like that? Don’t all the fans pull air up? That would mean an unsupported fan blade would move downward. Would that be the dynamic brake fan that launched?
That’s what I thought, but I wasn’t sure. That is what is sparking, and smoking isn’t it. So that means the train had it’s dynamic breaks on, and the fan blew.
Losing a fan is not as bad as having a turbo blow. When a turbo blows, there goes the engine it is “DOA”. Blow a fan and the engine can still run for a while. The DB’s may fry due to excess heat or the radiator may overheat, but the engine can keep going.
The same role it plays in an automotive (that includes trucks) engine. This Wikipedia entry explains it better than I can, although I’m sure the mechanics here present can add some depth.
EMD didn’t use a turbo early on - relying instead on the ‘Roots Blower,’ which, as I recall, is driven off the crankshaft.
I can tell you from personal experience that losing the turbo (or in the instance I had, the hose from the turbo) really takes the umph out of the engine.
The black smoke for which ALCO’s (especially the early RS’s) are famous was due to turbo lag - the turbo spooling up well behind the engine’s demands.
IIRC correctly the SD40-2 turbo is gear driven in throttle 2-5, in throttle 6 the clutch disengages and it becomes “Free” and spins on exhaust pressure. Once in a while the clutch fails to work as intended, the engine will bog down from lack of air and black smoke results and eventually it dies. If you have ever seen a puff of smoke and heard a “Whoomp” sound, that is a turbo screen (located at end of exhaust manifold and turbo inlet) plugged up with carbon or spare parts. Usually happens in higher throttle positions and will clean itself out. If it doesn’t, reduce throttle until the whoomp stops or isolate unit.
The first video shows what looks to be a hole in the side toward the rear of the brake grid blister. If both brake fans are not working you get a “Grid blower failure” and dynamic braking is locked out (until module reset) on that unit.
If a radiator fan blows off you keep going unless the radiators got damaged (soon to be out of water) by flying debris. If unit runs hot it will reduce to #6 throttle, if still too hot will shut down.
EMD Turbo failure vs. Turbo surge vs. turbo clutch failure. These are three different animals. None are good, but some are worse than other. Turbos usually fail for foreign material damage or overspeed. In both cases you completely lose your ability to make any airbox pressure at all. The governor will try to keep the engine speed up by moving the rack in and backing off the load. The result is lots of black smoke for a short while and then the engine will shut down. Turbo clutch failure means the scavenging air supply is greatly compromised in the lower notches. The governor will react by dropping load and increasing fuel to keep the engine speed where it should be for that notch. The result is lots of black smoke and an engine that might keep running but wouldn’t be of much use. Turbo surge occurs when there are plugged air filters, sometimes combined with high altitude, where the turbo’s compressor can’t withstand the pressure differential between the outlet side and the inlet (when the air filters are plugged, the compressor tries to pull a vacuum). When the pressure differential gets too great, the airbox pressure whooshes backward thru the compressor, the engine starves for air, the governor drops load and increases fuel. The result is a big puff of black smoke and then things get back to normal for a while until the pressure differential gets to great again.
The DB fans are powered by being wired in parallel with part of the DB grid resistors. Should that part of the grid resistor burn or otherwise become open, the fan motor will overspeed
Re Alco Turbo lag & smoke. Essentially what happens is this. In normal operation the turbo charger burns very hot(1200-2000 deg F ) & this burns any unburned fuel that comes out of the engine cylinders. The turbos on Alcos are very slow to spin up. As a result a lot of unburned fuel gets thrown in to the exhaust. Black smoke from the exhaust is unburned fuel. There was a pic of an RS 11 some years back pulling a train of empty auto racks throwing massive amounts black smoke out. This may have been a unit with a failed turbo that just was not burning anything.
What an exhaust turbo does is to take the air from the exhaust which is under considerable pressure, burn fuel in the combustion chamber and then route the pressurized air back into the intake manifold. The intake manifold normally is under a vacuum and pushing air into the intake boosts the pressure in the cylinder. (wish I know how to put a drawing into this)
Diesels are real ugly as far as the amount of unburned fuel that is in the exhaust. One of the big advantages of Turbos is that the turbo burns the unburned fuel(It was one of the reasons Santa Fe went to using GP-39-2’s in the Denver area in the 70’s) . Most of the better pollution control equipment for diesels tend to use turbos as the first stage of cleaning exhaust. The high pressure in addition to temperature goes a long way to cleaning up the exhaust.
The newer micro processor controlled engines specifically do not spin the engines up(ie add more fuel to the cyliners) until the turbo is spun up. I remember reading somewhere one of the bigger complaints of locomotive engineers is that the newer engines(specifically GE’s) load up very slowly. This is understandable as turbines take longer to spin up then does the engine itself.
Also when a turbo blows(at least on a truck) it is very very loud, and produces considerable amounts of smoke. the smoke is
When a turbo truly “lets go” the case will provide very little protection from shrapnal. The giant intercoolers on GE FDL’s helped more with that. one of the many reasons we cannot be outside the cab when loadboxing a C45 is due to the turbos desire to come apart. (yes even with the “new and improved” turbos) an EMD turbo generally will be driven by the gear train until it gets to 85-90% load, then it starts to free wheel. even on GE’s or most other engines the turbo really doesn’t add much until you approch 30-35% load.