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Alco/GE air cooled turbochargers

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Alco/GE air cooled turbochargers
Posted by soilredneck on Saturday, May 2, 2009 5:19 PM

Does anyone know the engineering problems that caused the air cooled turbos on early Alco locomotives to be so troublesome.  I realize that maybe the following comparisons are invalid, but why?

The International 1466 tractor has an air cooled turbo, and in my farm experience this engine under full load ran reliably for years.  The one difference in layout is that the engine cooling fan not only forced air through the radiator but also around and through the engine, including the turbocharger which hangs directly to the side of the engine.  This engine operated at 180 degress on the water temp. meter and about 200 degree of oil temperature under full load.  Any temporary extra load would raise water temps, but as soon as the engine recovered RPM's and resumed normal full load, water temps immediately returned to normal. 

Is the difference in engine and turbo sizes the only cause of Alco's problem?

 

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Posted by creepycrank on Saturday, May 2, 2009 6:02 PM
Its the bearings that are cooled by the oil flow. On locomotives all the turbos are air cooled. If an engine runs at a very high load factor for awhile but is suddenly shut down without a separate source of cooling oil to take away the heat from the housing the heat can cause the housing to warp. Normally an engine that is allowed to run at idle for at least 10 minutes will cool every thing off adequately as the exhaust temperature is only 200 degrees. The new GEVO engine has air to air aftercoolers with some very bulky ductwork which may be what you are thinking of.
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Posted by soilredneck on Sunday, May 3, 2009 4:36 PM

I was not refering to inter/aftercooling, which is a farily recent development in use in almost all current diesel engines including farm use, in order to help fuel effeciency as well as meet current EPA emissions.

 I cannot think of a better way to describe what I want to know-most magazine articles that talk about this early alco problem refer to air cooled and water cooled turbochargers.  The exhaust stack was always repostioned on the locomotives because of the change to water cooled turbos.

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Posted by SSW9389 on Sunday, May 3, 2009 7:07 PM

A General Electric constant pressure aircraft type of turbocharger was first used with the 12 cylinder 241 engine in 1944. GE engineers developed the RD-1 turbocharger to be used with the 12 cylinder engine and the RD-2 was to be used used with the 16 cylinder engine. Testing with the GE turbochargers revealed the need for a new manifold design to increase horsepower output. The 244 engine program had developed parallel to the 241 engine program and soon superceeded it in ALCO's quest to produce a competitive freight diesel to EMD. The GE RD-1 and RD-2 turbochargers were carried over from the 241 engine program to the 244 engine program.

"The problems associated with the turbocharger and exhaust manifold were equivalently serious to those associated with the crankshaft." wrote Richard Steinbrenner p 283 of Centennial Remembrance. Yes ALCO's push to enter diesel production without completely tested engines and turbochargers led to road failures. The very early air cooled turbochargers had single pipe manifolds that were replaced with three (12 cylinder) and four (16 cylinder) pipe designs. The manifolds were subject to heat cracks. The turbochargers experienced bearing failures and fractures at the nozzle blocks and exhaust hood welding. Because of these problems GE developed the RD-3 and RD-4 water cooled turbochargers which became available in June 1953. ALCO followed with the 510 and 710 water cooled turbochargers in September 1954.

The above data is found in Chapters VII and IX of Richard Steinbrenner's excellent The American Locomotive Company A Centennial Remembrance.  

   

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Posted by Tugboat Tony on Saturday, May 9, 2009 2:08 AM

To this day GE utilizes a water cooled turbo. Which as you can imagine has it's own set of troubles but does not require a seperate oil pump that EMD uses. the turbo pump on an EMD runs before the engine is started to ensure the bearings are well lube'd and for 35 minutes after a shutdown to cool the bearing afterword.  a very trouble free design compared to plumbing water through a glowing hot turbo.

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Posted by edbenton on Saturday, May 9, 2009 9:58 AM

Tugboat take it from a Heavy Duty Diesle Mechanic.  A Water cooled Turbo that GE uses is Easier on oil than EMD's NON watercooled one is.  Also A water cooled one you have less turbo failures due to bearings coking up and then the shaft failing.  What you are forgetting on an EMD is they are Superchargers/Turbos where they are driven with a Mechanical Clutch til notch six were the engine FINALLY produces enough Force to Spin the Turbo itself and then the clutch disengages.  Any of the larger diesels used in Marine use have a WATER cooled turbo for one reason THEY LAST LONGER.  In the OTR industry guess what is the highest failing piece of equipment on the engines THE TURBO for one reason they are NOT WATER COOLED.  You can not subject oils to 12-1400 Degree exhaust temps and expect it NOT to convert to black carbon and plug up the returns and start to scroe bearings and shafts that happens say bye to your turbo.

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Posted by creepycrank on Saturday, May 9, 2009 11:02 AM
Heavy duty mechanic I don't know what your talking about. If an EMD turbo has a failure due to lack of lubrication it will be because the turbo filter is plugged up and the low lube oil pressure alarm isn't functioning. If the soak back pump doesn't come on when an engine is shut down the recommendation is to restart the engine and run for 15 minutes I think, at idle in which the exhaust gases being only about 200 deg. F will cool the turbo. I've known of marine engines that ran for years without the soak back pump working mostly as the prelube the whole engine every time they start up and that gets the turbo too. The EMD turbo is properly designed to run without any cooling except that provided by the oil flow. This doesn't had anything to do with the subject matter except GE has their own version of EMD turbos and the only design change is the turbine blade root.
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Posted by edbenton on Saturday, May 9, 2009 12:21 PM

Correct You will see more Stack fires in GE's for one reason ONLY the Turbo RUNS COOLER.  At 1200 Degrees the turbo is cooking anything it touches.  Put it to you this way I worked on Heavy Trucks then Drove them after I turned 21 guess what I never had a Turbo blow on me why I knew how to baby the SOB's to make sure it never got hot enough to cook itself to death.  I would rather have a few extra water lines going to a turbo cooling her down to keep it cooler tan risk having one explode at higher elevations when that is all that is keeping my train running and remember this with an EMD you loose the Turbo you loose the ENGINE also since you loose the ability to SCAVANGE the motor since it is a 2 stroke at least if a GE blows its turbo it will STILL RUN.

Always at war with those that think OTR trucking is EASY.
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Posted by creepycrank on Saturday, May 9, 2009 1:40 PM
edbenton

Correct You will see more Stack fires in GE's for one reason ONLY the Turbo RUNS COOLER.  At 1200 Degrees the turbo is cooking anything it touches.  Put it to you this way I worked on Heavy Trucks then Drove them after I turned 21 guess what I never had a Turbo blow on me why I knew how to baby the SOB's to make sure it never got hot enough to cook itself to death.  I would rather have a few extra water lines going to a turbo cooling her down to keep it cooler tan risk having one explode at higher elevations when that is all that is keeping my train running and remember this with an EMD you loose the Turbo you loose the ENGINE also since you loose the ability to SCAVANGE the motor since it is a 2 stroke at least if a GE blows its turbo it will STILL RUN.

I think the problem with GE stack fires is a leak past the compressor oil seal. I don't know about GE turbos but on EMD they are labyrinth seals but with positive air box pressure and a vacuum on the oil pan where the oil is draining back . A 4 stroke has got a problem at idle in that there could be a vacuum on the compressor seal with plugged air filters or any other reason the turbo isn't turning up, with a labyrinth seal there is now a vacuum behind the impeller and oil can get into the cylinders. The GE turbos maybe water cooled to protect positive type seals that can't stand much heat. It can be very dangerous to continue to run an engine with a failed compressor seal in this case as the engine will run on its own lube oil.
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