RT: What do the throttle positions relate to?

I know idle is the lowest speed the prime mover turns at while notch 8 is the fastest, more or less.  How do run/notch 1 to 7 relate?  That is, does each advance double the speed, doubles the horsepower, doubles torque to generator/alternator, or doubles the voltage of generator/alternator output under full load, or none of the above?  I know there is a governor that comes into play, but just wanted to understand what run/notch numbers relate to.

I had one EDM engineers manual that showed the RPM for each notch, but the numbers didn't seem to make sense such as ratio to each other, or logarithmic, or percentage of previous step. They were just "odd" numbers 734, 852, 947 etc (numbers made up but you get idea).

Thanks

Original Post

The different throttle positions equate to an attempt at providing equivlant/equal power level increases for the Engineer. Since the prime mover diesel engine simply drives a main generator/alternator, the specific engine RPM for each throttle position is mainly based around avoiding critical vibration points. Thus, one will see some pretty strange RPM governor settings, back in the days prior to computer controlled electronic fuel injection. 

I can't remember ever seeing such an instruction.  On expedited trains in non-grade territory, the throttle positions I used most were 1, 3, 5, and 8.  This, of course, was when stretch braking was permitted.  Longer, heavier, trains required the use of all throttle positions.

Perhaps one railroad in particular had that instruction. (?)

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

Kelly Anderson posted:

I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible.  Is that correct, and if so, why?

I never ran any EMD unit that caused any problem in 5th notch. I never cared for the 35 series locos. Not that they were problematic, it was just that they did not have enough power. Some EMD units didn't like the 2nd notch and SOME of those 10 cylinder models shook themselves to death just idling!!!

Big Jim posted:
Kelly Anderson posted:

I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible.  Is that correct, and if so, why?

I never ran any EMD unit that caused any problem in 5th notch. I never cared for the 35 series locos. Not that they were problematic, it was just that they did not have enough power. Some EMD units didn't like the 2nd notch and SOME of those 10 cylinder models shook themselves to death just idling!!!

Must admit that I've heard about any avoidance instructions concerning throttle #5, with ANY EMD units.

What company offered "10 cylinder models"? 

Might have been 12, but the way they vibrated they could have been 3, 5,7, 9...pick a number! Whatever those POS were, they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! My hatred for the things was so great that I didn't care to know anything about those rattle-traps! Woe be onto you if you had to sit on one for any length of time waiting to make a move!
They used to put them on work trains. You could be on another train and pass one in the clear and watch them shaking themselves to death!

Big Jim posted:

Might have been 12, but, whatever those POS were they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! W#oe be onto you if you had to sit on one for any length of time waiting to make a move!

Oh, right,,,,,,,the darned 12 cylinder. Yes, even the old 12-567 engines vibrated in certain throttle positions, but then the 12-645, especially the turbocharged versions were REALLY bad. In fact, the Australians complained so loudly that EMD was forced to re-design the crankshaft & corresponding firming order, under a warranty policy adjustment, for those Australian units with 12-645E3 engines.

Since we are on the subject of the EMD 5th Notch, I'll relate this. When coming up out of a dip and going from DB to power, you couldn't skin 'em back past the 5th notch or you would trip the governor. You had to wait for the transition to catch up before going to the higher notches.

Hot Water posted:
Big Jim posted:

Might have been 12, but, whatever those POS were they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! W#oe be onto you if you had to sit on one for any length of time waiting to make a move!

Oh, right,,,,,,,the darned 12 cylinder. Yes, even the old 12-567 engines vibrated in certain throttle positions, but then the 12-645, especially the turbocharged versions were REALLY bad. 

Aha!  Thankfully, it wasn't just me.  I never knew that it was a real problem, but the vibration on SD39 and GP39 units annoyed me.  Fortunately, we had few of those units on the Coast Lines.  Those poor Santa Fe Engineers in the midwest and New Mexico had to deal with SD39's and GP39's on a daily basis.

Plus, they only ran fast downhill.  Oh, well, as I have said, "You get what you get and you don't pitch a fit."  The paychecks I earned aboard those 12-645 powered engines cashed just fine at the bank.

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

Hot Water posted:
Big Jim posted:

Might have been 12, but, whatever those POS were they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! W#oe be onto you if you had to sit on one for any length of time waiting to make a move!

Oh, right,,,,,,,the darned 12 cylinder. Yes, even the old 12-567 engines vibrated in certain throttle positions, but then the 12-645, especially the turbocharged versions were REALLY bad. In fact, the Australians complained so loudly that EMD was forced to re-design the crankshaft & corresponding firming order, under a warranty policy adjustment, for those Australian units with 12-645E3 engines.

Was the 12-645 non-turbo the prime mover for the GP38 and -2?  I though the 38's ran like Tmex watches?

The TEXAS SPECIAL:  The REAL RED streak of the golden prairies!

Number 90 posted:
Hot Water posted:
Big Jim posted:

Might have been 12, but, whatever those POS were they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! W#oe be onto you if you had to sit on one for any length of time waiting to make a move!

Oh, right,,,,,,,the darned 12 cylinder. Yes, even the old 12-567 engines vibrated in certain throttle positions, but then the 12-645, especially the turbocharged versions were REALLY bad. 

Aha!  Thankfully, it wasn't just me.  I never knew that it was a real problem, but the vibration on SD39 and GP39 units annoyed me.  Fortunately, we had few of those units on the Coast Lines.  Those poor Santa Fe Engineers in the midwest and New Mexico had to deal with SD39's and GP39's on a daily basis.

Plus, they only ran fast downhill.  Oh, well, as I have said, "You get what you get and you don't pitch a fit."  The paychecks I earned aboard those 12-645 powered engines cashed just fine at the bank.

ATSF seemed to "like" the GP39 and -2.

Is stretch brakin allowed anymore?

The TEXAS SPECIAL:  The REAL RED streak of the golden prairies!

Dominic Mazoch posted:
Hot Water posted:
Big Jim posted:

Might have been 12, but, whatever those POS were they were the worst EMD locos ever made, and at the time I didn't think EMD could make a bad loco! W#oe be onto you if you had to sit on one for any length of time waiting to make a move!

Oh, right,,,,,,,the darned 12 cylinder. Yes, even the old 12-567 engines vibrated in certain throttle positions, but then the 12-645, especially the turbocharged versions were REALLY bad. In fact, the Australians complained so loudly that EMD was forced to re-design the crankshaft & corresponding firming order, under a warranty policy adjustment, for those Australian units with 12-645E3 engines.

Was the 12-645 non-turbo the prime mover for the GP38 and -2?

No. The 38 series, both GP and SD had roots blown 16-645E prime movers. The 38 series and 38 "Dash 2" series were NOT turbocharged and all had 16-645E prime movers.

 I though the 38's ran like Tmex watches?

They did, because they were NOT 12 cylinder!

 

Dominic Mazoch posted
ATSF seemed to "like" the GP39 and -2.

Is stretch brakin allowed anymore?

Yes, they had 20 SD39's, all Locotrol equipped and mostly used on coal or potash unit trains; and they had several dozen GP39-2's, heavily used in Texas and Kansas.

Stretch braking is no longer condoned by BNSF.  On the rare occasions when a local would be powered by rebuilt GP7's and GP9's that no longer had dynamic braking, what else could one do?  But, almost all road trains are powered by big GE and EMD power that has the capability to record so many events that the chart won't fit on regular size paper.  Those locomotives download their event recorders at fuel stops, into a huge database that is accessed by an exceptions program.  That software program rubs the events together, can identify stretch braking and several other forbidden practices, and produces a report, rating Engineers on their compliance with train handling instructions.

So, stretch braking?  No, no, no.  

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

Tom:

I worked for Duval Corporation and successor Western AG-Minerals and can remember those locotrol units on our export potash trains coming out of the Carlsbad basin.  I also recollect that John McCracken, the Santa Fe trainmaster in Carlsbad didn’t care much for them.

Curt

Machines have a condition called resonance where a natural frequency can be struck, and trouble ensue.  "If rotating machinery is operated at or near the natural frequency for free vibrations of the system, abnormally large vibrations may result." (Dynamics by J.L. Meriam).  That's why lathes, for example, have designated speed steps or you could run them at speeds where they will thrash about, unbolt themselves from the floor, and start dancing.  You can put a device off from the machine to serve as an outlet for some of that energy, but better to avoid the condition if at all possible.  My mother's four-door Ford sedan had a solid metal cylinder in free space welded to the end of a piece of steel bar stock welded to the chassis.  That was there to vibrate instead of the car when it hit specific speeds.  Sounds like maybe some of your handrails played that role as well.  

David Horn

Math in Railroading, one & two generations ago--

Some time back I had commented that raising HP by adding cylinders faced problems because the crankshaft being heavier would have critical vibration frequencies (in torsion) moved to lower RPMs.  HOT WATER then commented that often some of the run points would be placed between critical vibration RPM.  I was curious to see how well this might have worked, and much later I found some EMD calculations (for 8 cylinders): some vibration but apparently not to runaway amplitudes if the time between run settings was not too slow.  What stood out was that these calculations had been done by hand.   Don't recall how I knew, but I had some experience:

In the time frame 1959-60 school year, I chose to look into matrix computations, having heard this would be the coming thing in engineering math.  My new school did not lack for quality of its instructor, to the point where, having divided us into teams of two, and my teammate promptly quitting, this instructor saw this as a trivial problem.  Perhaps I was compensated by getting first choice of the several methods of solution that the teams would compare.

The class problem was a 6x6 matrix, for a 4-cylinder gasoline engine, plus rear flywheel and front vibration damper; there are 6 critical rpm's for vibration.  Perhaps of interest is that the largest matrix (in the 70's) that the really good hand-held engineering calculators could handle was 6x6.  The only computer on campus was the bookkeepers' IBM 650, to be programmed in machine language, and loaded by hand-punched cards, on an evening loan once a week.  (I actually got output even though it was extemely difficult to program.  Well, it was only an electronic Frieden.)

 My recollection is that EMD actually further reduced the burden of manual calculation by quartering an 8 by 8 matrix as their results displayed less that the full eight singularities.  Using a 4x4 matrix & assuming the number of operations as n^4 (n to the 4th) the effort will be cut by a factor of 256.  The problem is called the "Eigenvalue" problem, to extract these from a matrix.  I think setting the input up per the "tri-diagonalization" method is most suited for reduction to extracting a 4x4 corner for the actual calculation work.

As a measure of the advance of capabilities in matrix work, in 1975, a mattrix of 276x276 was used for a very acute angle (30 deg) crossing of a curved bridge over 5 electrified tracks of the PRR, by then PC.  Run in STRESS or STRUDEL, there was failure to converge to a solution.  A suggested renumbering of nodes placed the most significant input data as close to the diagonal as possible, as above.  It worked, using a 4 MHz GA (similar to a 1 MHz IBM 1130, but with 17k core).  Five years passed before such a difficult design was finally repeated in this country.

I can't recall exactly the calendar dates that higher horsepower engines were sought, but the end of the 50's  can't be far off.  What I am thinking is that the vibration analysis of 12-cylinder engines was a lot less needed calculation, and a lot more risky guesswork, as I look at the history of what could be done at the time and what it would have cost to have done more.

--Frank 

In the early 2000's I worked as a race mechanic and pit crew member for an ARCA Series team, which uses old NASCAR Cup cars and engines, but is run on a fraction of the budget.  The better off teams could runs the engines at their NASCAR design RPM of roughly 9000-9200 RPM for that era.  (Eventually, the engines were knocking on 10,000 RPM before NASCAR mandated spec rear end gear ratios to save development costs). The team I worked for was decidedly low budget, and we would gear the car to turn the engine much slower to avoid wear and tear on the parts.  It worked well, but the change of running those engines at 8000-8200 RPM instead of the higher number was brutally hard on valve springs, especially at tracks like Pocono and Michigan with very long straightaways.  It wasn't uncommon after a 200 mile Pocono race to have 2-4 broken valve springs.  The springs had an inner and outer spring, and would usually only break outer one, so the engine would only lose power, not drop the valve onto the piston. 

Kelly Anderson posted:

I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible.  Is that correct, and if so, why?

"For proper traction motor cooling, the locomotive should never be operated on grades below the 5th throttle position."

This quote from the helper/pusher thread must be what I was thinking of.  I would assume that below the 5th notch, slower engine RPM results in less traction motor cooling air.  Is that it?

Kelly Anderson posted:
Kelly Anderson posted:

I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible.  Is that correct, and if so, why?

"For proper traction motor cooling, the locomotive should never be operated on grades below the 5th throttle position."

This quote from the helper/pusher thread must be what I was thinking of.  I would assume that below the 5th notch, slower engine RPM results in less traction motor cooling air.  Is that it?

Correct. With the advent of the GP20/SD24 and the GP30, the traction motor & main generator blower was mechanically driven off the engine rear gear train. Thus, the slower the engine RPM, the less cooling air for the main generator and traction motor blower. 

 

Kelly Anderson posted:
Kelly Anderson posted:

I (dimly) recall reading in an operator's manual for GP35's, that engineers were advised to avoid using Run 5 as much as possible.  Is that correct, and if so, why?

"For proper traction motor cooling, the locomotive should never be operated on grades below the 5th throttle position."

This quote from the helper/pusher thread must be what I was thinking of.  I would assume that below the 5th notch, slower engine RPM results in less traction motor cooling air.  Is that it?

We were never advised of any restriction like that. If it took the fifth notch to stay at the prescribed speed, that is what was used. Never had a problem.

Many decades ago, I recall riding on the Fort Belvoir Railroad (now gone) locomotive, and the engineer was explaining the various notches in terms of changing connection to the traction motors, putting their components into various combinations of series and parallel.

Which leads me to ask, when diesels are not idling, do they run at (or near) a specified RPM with a governor controlling feed of the fuel to hold it at that RPM under varying electrical load?

RJR posted:

Many decades ago, I recall riding on the Fort Belvoir Railroad (now gone) locomotive, and the engineer was explaining the various notches in terms of changing connection to the traction motors, putting their components into various combinations of series and parallel.

Which leads me to ask, when diesels are not idling, do they run at (or near) a specified RPM with a governor controlling feed of the fuel to hold it at that RPM under varying electrical load?

Yes. The Woodward PG Governor. Now of course, everything is computer controlled, especially the electronic fuel injection.

 

The GE U25's had 16 notch throttles.  The "half notches" were used to increase generator excitation but not diesel engine rpm.  (That is, the half notches would increase tractive effort but minimize an increase in horsepower.)  At that time, the thinking was that the horsepower "steps" were much greater from notch to notch on a 2500 HP loco than the then current 1750 HP locomotives, and would have a tendency to break knuckles.  Since most applications called for three units, that would be a horsepower difference of 7500 vs 5250.  That master controller also had "detents" so that an engineer could not "sweep" the throttle as used on EMD's, and of course that was a disaster when the U Boats were in applications that called for some switching.  I do not remember when the 16 notch scheme was discarded, it might have been with the U30's, but all of this "went away" when the FRA mandated a common  and standard set of control movements for all locomotives, but I think that GE discarded the 16 notch before this.  As a side, the change to the master controller also obsoleted the non standard U Boat reverser "key". Every engineer carried an extra reverser key in his grip.  The 16 notch key would barely fit in a grip!

Not well known, but the first U25 demonstrators had a master controller "hung" from the ceiling with a "grapevine" throttle similar in position to the throttle of a steam locomotive.  So the 16 notch on the production U Boats was actually the second design to be used.

Hot Water posted:
RJR posted:

Which leads me to ask, when diesels are not idling, do they run at (or near) a specified RPM with a governor controlling feed of the fuel to hold it at that RPM under varying electrical load?

Yes. The Woodward PG Governor. Now of course, everything is computer controlled, especially the electronic fuel injection.

On our SW8, (equipped with a 567 V8) when moved from idle to run 1, she will lug down to a startling degree for a second or so until the governor compensates.  Also when dragging a heavy train up grade, she will lug down a few percent of RPM even in run 8.  if she looses traction, you can hear the engine rpm rise in concert.

Kelly Anderson posted:
Hot Water posted:
RJR posted:

Which leads me to ask, when diesels are not idling, do they run at (or near) a specified RPM with a governor controlling feed of the fuel to hold it at that RPM under varying electrical load?

Yes. The Woodward PG Governor. Now of course, everything is computer controlled, especially the electronic fuel injection.

On our SW8, (equipped with a 567 V8) when moved from idle to run 1, she will lug down to a startling degree for a second or so until the governor compensates.  Also when dragging a heavy train up grade, she will lug down a few percent of RPM even in run 8.  if she looses traction, you can hear the engine rpm rise in concert.

Hmmmmm. Sounds like your governor might be a bit sluggish. Maybe a change of oil in the governor might be in order, also what weight oil has been in the governor, and what is being used now? However, a little bit of "speed droop" is not uncommon, and RPM increase during a wheel-slip is common for those older units.

Hot Water posted:
Hmmmmm. Sounds like your governor might be a bit sluggish. Maybe a change of oil in the governor might be in order, also what weight oil has been in the governor, and what is being used now? 

And that's a good question to ask.  

Governor oil looks red.  It's a thin product.  If the governor leaked and ran too low on fluid, some well-meaning but misguided person might have filled 'er back up with motor oil if no governor oil was easily available.  It would not be the first time such a thing had happened.  See if there is visible governor oil to the full mark, and is it thin and red?

When I was an Engineer, I always carried a bottle of governor oil in my grip.  

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

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