Turbo Failure?

[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. 

[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

[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 

[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.

[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.

 

[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)

[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 

 

 

[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.

[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.