Turbo Failure?

[oltmannd]

In the world of freight train operation, the difference between getting to full load in 20 seconds or a minute and a half really doesn't matter much, so I suppose that's why they don't give the turbo a "boost" up to speed.  It's OK to load slowly to keep the smoke down.

As for the emissions, I'm not sure, but I beleive the requirements are for steady state.  There are relatively few changes in throttle postion compared to highway operation, so transients don't matter nearly as much.

[gamcgee]

I am surprised (or maybe they did) that no locomotive manufacturer toyed with using some of the available compressed air to spin up the turbo faster.  I remember an article about a racing team that was using nitrogen to keep the turbo spinning so a driver didn't have the lag coming out of a corner.  It would seem that it would be easy to impliment with todays computer controlled engines as you could just program the ECU not to raise RPM until it detected some amount of boost in the plenum.

Does the EPA test locomotive engines in a steady state or do they check throttle up like on over the road diesels in CA?

 

Dave 

 

 

Where I work, we use 4900 HP Worthington diesels for emergency power, which use compressed air to get the turbos up to speed rapidly during startup.  The expectation being that the diesels will be online in the matter of seconds.

[broncoman]

I am surprised (or maybe they did) that no locomotive manufacturer toyed with using some of the available compressed air to spin up the turbo faster.  I remember an article about a racing team that was using nitrogen to keep the turbo spinning so a driver didn't have the lag coming out of a corner.  It would seem that it would be easy to impliment with todays computer controlled engines as you could just program the ECU not to raise RPM until it detected some amount of boost in the plenum.

Does the EPA test locomotive engines in a steady state or do they check throttle up like on over the road diesels in CA?

 

Dave 

 

 

[oltmannd]

Back in the Uboat and Dash 7 days, GE had all sorts of wacky ways of trying to deal with smoke and turbo lag.

The U25s had "half notches", where you could rev up the engine to the next notch's RPM but hold the lower notch's load.  I know that PC went to a straight 8 notch speed schedule, but there were still many engineers who would hold court on the theory of half notches!

Some of the U23s came with a 1-5-8 speed schedule where engine speed would increase to notch 5 speed as soon as you went to notch 2 and then to notch 8 speed when you hit notch 6.

This was replaced in the early 80s by "skip 3, double 6" in order to try to save some fuel.  By the notches, engine speed went 1, 2, 4, 5, 6, 6, 7, 8.

Dash 8s had a whole different set of wierdness.  Most of the engine speed schedules still keep the engine notch RPM ahead of the load notch, but will actually make notch 8 HP using notch 7 engine speed at lower train speeds (when the RPM isn't needed to keep the voltage up)

[gamcgee]

Talk about emissions, here's a photo I took this past week.

I was driving home from work in the afternoon, looking for photo opportunities, when I saw this empty southbound unit coal train sitting on the north side of New Buffalo, Michigan on the CSX Grand Rapids subdivision. As I set up for the shot, the signal comes in, and the engineer begins to move the train with BNSF 5671 (GE AC4400CW) leading, and BNSF 9676 (EMD SD70MAC) trailing. The lead unit put on quite a show.

 

[Randy Stahl]

So does the governor/ECU hold the RPMs at a set point for the notch that is the next step up even though it is more loaded (notch 5-6 and 7-8)?  Is this what  GE determined to be the engine's sweet spot (or spot of lesser emissions)?

Dave 

Exactly.

[broncoman]

So does the governor/ECU hold the RPMs at a set point for the notch that is the next step up even though it is more loaded (notch 5-6 and 7-8)?  Is this what  GE determined to be the engine's sweet spot (or spot of lesser emissions)?

Dave 

[Wyonate]

Yea that is a good question.  (I know whatit is now due to the replies)    I see that quite a bit on alot of locos around here, Northern Wyoming.  I live a the bottom of a 7 mile 2% and alot of AC locos come through here with those "burn marks."  I've noticed alot of the helpers have them too.  But all the helpers are DC locos, SD60Ms and SD75Ms. I'll have to take a closer look, but I think very few MACs have them.  Good topic!!!

Nate

[Randy Stahl]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

On my GE's , throttle 5-6 are the same engine speed and throttle 7-8 are the same speeds . You are correct when you say the engine speed stays the same and only more load is put on the engine.

 

What about 1 through 4 are they the same engine speed?

Joe

Sometimes idle and notch 1 are the same otherwise 2-4 are all different speeds

 

Is this also similar on EMD's or are they difrent?

 

 

Thanks for the help

Most of not all of the EMD's I'm familier with have 8 engine speeds. 

[silicon212]

I don't know about other EMDs, but I can tell you that on an SD/GP40-2, idle and notch 1 are the same RPM - just one isn't engaged.

[mj5890]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

On my GE's , throttle 5-6 are the same engine speed and throttle 7-8 are the same speeds . You are correct when you say the engine speed stays the same and only more load is put on the engine.

 

What about 1 through 4 are they the same engine speed?

Joe

Sometimes idle and notch 1 are the same otherwise 2-4 are all different speeds

 

Is this also similar on EMD's or are they difrent?

 

 

Thanks for the help

[Randy Stahl]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

On my GE's , throttle 5-6 are the same engine speed and throttle 7-8 are the same speeds . You are correct when you say the engine speed stays the same and only more load is put on the engine.

 

What about 1 through 4 are they the same engine speed?

Joe

Sometimes idle and notch 1 are the same otherwise 2-4 are all different speeds

 

[mj5890]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

On my GE's , throttle 5-6 are the same engine speed and throttle 7-8 are the same speeds . You are correct when you say the engine speed stays the same and only more load is put on the engine.

 

What about 1 through 4 are they the same engine speed?

Joe

[Randy Stahl]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

On my GE's , throttle 5-6 are the same engine speed and throttle 7-8 are the same speeds . You are correct when you say the engine speed stays the same and only more load is put on the engine.

[mj5890]

So between 4 and 5 there is a RPM and load change but other times increaseing the throtle will just put more resistence on the engine to make more electricty but the RPM stays the same but the engine works harder at that rpm?

[BigJim]

So THAT's why Run 4-7 on a GE is the same engine RPM

There is a big difference in speeds between 4 and 5.

[silicon212]

Thanks BigJim, so what your saying is that its as simple as going from 4th to 5th notch.  Also why is this more common on the Dash 8's?

Thanks

Joe

Big Jim is right on , it seems that often on older GE's when ever you change a throttle setting that requires an engine speed change you run the risk of a flamer. Most if not all GE's do NOT have 8 different engine speeds because of this. The newer GE's with EFI are much more responsive to load and engine speed demands.

 

 

So THAT's why Run 4-7 on a GE is the same engine RPM, just different loads on the generator I suppose.

[trainfan1221]

The old NJDOT-NJT U34ch locomotives ran at a constant speed, run 6 I believe, in passenger mode.  They simply loaded when the throttle was let out but shot a flame out of the stack anyhow, only visible at night.  But they still sounded great.

[Randy Stahl]

Thanks BigJim, so what your saying is that its as simple as going from 4th to 5th notch.  Also why is this more common on the Dash 8's?

Thanks

Joe

Big Jim is right on , it seems that often on older GE's when ever you change a throttle setting that requires an engine speed change you run the risk of a flamer. Most if not all GE's do NOT have 8 different engine speeds because of this. The newer GE's with EFI are much more responsive to load and engine speed demands.

 

[BigJim]

You'll have to ask the shop guys on this forum about that. I just run 'em.

If you don't mind doing some research on the TRAINS forums, there has been quite a lot posted about this exact phenom in the past year or so.

[mj5890]

Thanks BigJim, so what your saying is that its as simple as going from 4th to 5th notch.  Also why is this more common on the Dash 8's?

Thanks

Joe

[BigJim]

mj,
This is most prevalent on Dash-8's. It has to do with the GE's being a true turbocharged 4 stroke engine. The 4 stroker can suck air into the cylinders and the turbo doesn't really start working until about the fifth notch. So on the change from forth to fifth notch the fuel gets dumped into the cylinders when the turbo hasn't caught up and pushed enough air for the proper air/fuel ratio. So you get a bunch of black smoke (unburned fuel) and after the mixture gets right it all catches fire outside the stack.

This is not the reason for the burn marks. Those burn marks, as pictured above, are caused by an internal fire of some sort.

[mj5890]

That's a pretty normal thing for GE's to do. Especially Dash -8's. I could probably make that happen on demand about 50% of the time. There have been numerous discussions w/pictures about this on several forums. It is a spectacular sight, eh?

So when the fire ball comes out of the stack is it because of the same reason as burn marks on the side(leaking fuel lines) or is it a diffrent reason.

Also BigJim you say you can make this happen on demand about 50% of the time, what type of locomotive can you do it on, and how do you do it?

Thanks

Joe

[Boomer Red]

     After seeing these pictures I sure wouldn't want to walk through the engine room on one of the "Cowl Body" Dash 8s like CN runs. Especially if the engine was working hard!

[Jake1210]

I've noticed quite a few locomotives from several different roads have this kind of paint damage.  Is this caused by turbo failure?  Seems to be quite common.  Sure ruins the paint job.

Here's a photo I took today.

 

 

Really? I always thought it was caused by stack fires due to poor internal planning. This problem is more common with GE roadswitchers, mainly the U-boat series and some AC4400CW's (unsure about AC6000CW's). Usually the hood section would need repainting which means one end could be a different shade than the other. Some Class-1 railroads repaint the entire locomotive which is costly ($5000 per loco?).

Of course, it is interesting to see.

 

I'd imagine that it would be at least $20K with all the pain that goes on those things.

[silicon212]

As a westbound approached, a HUGE fireball erupted out of the exhaust stack. 

That's a pretty normal thing for GE's to do. Especially Dash -8's. I could probably make that happen on demand about 50% of the time. There have been numerous discussions w/pictures about this on several forums. It is a spectacular sight, eh?

When the SP AC4400CWs were still fairly new, just after UP took over, one of them was leading a train on the Phoenix line.  At the Dobson crossing, I was watching it proceed eastward, when a huge, bright fireball (perhaps 20 feet tall!) erupted out of the stack and proceeded to burn for about 2-3 seconds.  It was pretty spectacular as it was during night time when I saw it.  I figured it was just the GE "trying to show who's boss".

[BigJim]

As a westbound approached, a HUGE fireball erupted out of the exhaust stack. 

That's a pretty normal thing for GE's to do. Especially Dash -8's. I could probably make that happen on demand about 50% of the time. There have been numerous discussions w/pictures about this on several forums. It is a spectacular sight, eh?

[gamcgee]

I've seen the burn marks at various locations along the prime mover compartment: the generator end, the middle, and the exhaust end.  The picture I included was just one example, which showed damage at the generator end.  The reason I asked about turbo failure is that I have seen it first hand.  One evening I was trackside on the Conrail (NS) Chicago Main.  As a westbound approached, a HUGE fireball erupted out of the exhaust stack.  It sure got my attention!  I thought, perhaps, if a locomotive was traveling backward, the flames could damage the paint on the generator end.

I work in nuclear power.  At my plant, we have four big Worthington diesels that are used for emergency backup.  Knowing what I know about those, I think Clash and Randy gave us a good explanation.  Because this seems so common, it would seem to me that the locomotive builders would want to rectify this.  It doesn't speak well of that particular aspect of the design.  I wonder if this kind of damage is covered under warranty.

By the way, nice picture.  It would be interesting to see more photos that others have taken as well.

Regards 

[nsrayman]

this one burned as well ,   it also burned up when it was painted Conrail.