Gentlemen,

If one of the two diesel/DC generator sets shuts-down for some reason while pulling a train, does the current produced from the remaining operative diesel/DC generator set go to only one or both pairs of traction motors?  

I’m assuming that each diesel/DC generator set was permanently wired to one truck (2 motors) and isolated from the other.  

 

Original Post
PRR 5841 posted:

Gentlemen,

If one of the two diesel/DC generator sets shuts-down for some reason while pulling a train, does the current produced from the remaining operative diesel/DC generator set go to only one or both pairs of traction motors?  

Each engine generator, and its corresponding electric control circuitry, power ONLY the two traction motors in that truck specific truck. Thus, if one engine generator set "goes down", then THAT truck is unpowered.

I’m assuming that each diesel/DC generator set was permanently wired to one truck (2 motors) and isolated from the other.  

Correct.

 

 

Hot Water posted:
PRR 5841 posted:

Gentlemen,

If one of the two diesel/DC generator sets shuts-down for some reason while pulling a train, does the current produced from the remaining operative diesel/DC generator set go to only one or both pairs of traction motors?  

Each engine generator, and its corresponding electric control circuitry, power ONLY the two traction motors in that truck specific truck. Thus, if one engine generator set "goes down", then THAT truck is unpowered.

I’m assuming that each diesel/DC generator set was permanently wired to one truck (2 motors) and isolated from the other.  

Correct.

The normal diesel locomotive had one generator.  It would not make sense to have two generators each wired to a set of traction motors.  In any slow speed situation, one of two diesel engines would provide enough power for four traction motors.  IF only two motors were powered, the tonnage that could be moved at slower speeds would be halved.

What locomotives do you know had two generators ?

Malcolm Laughlin

I think the EMD E units had two MG sets.    Also I think the Baldwin Centipides did.

When those units were designed, it seems most diesel prime movers of the size that could be used in a locomotive were in the 1000-1500 HP range.    Hence to get a 2000 HP unit, EMD  used two prime movers.   

Diesels with 2000 and greater HP with one MG did not appear until the late 50s or early 60s.

 

It would not make sense to have each generator wired to a single truck.  And I fell pretty sure that the throttle did not have two completely separate sets of wiring.  With only one engine, you would not want to have power to only one of the trucks.  That would have made it impossible to start a heavy train because of wheel slippage.  With four motors getting power from only one engine, you could at least start the train but you would have a much lower top speed.

One thing I've learned on this forum is that Jack (Hot Water) is rarely incorrect based on his history of working for EMD and still being a certified steam locomotive engineer.  Not that it isn't important to check sources, but Jack is a huge database of knowledge.  He has helped me numerous times on various 3rd Rail projects.  Just my 2 cents.

 

Jonathan

 

mlaughlinnyc posted:

It would not make sense to have each generator wired to a single truck.  And I fell pretty sure that the throttle did not have two completely separate sets of wiring.  With only one engine, you would not want to have power to only one of the trucks.  That would have made it impossible to start a heavy train because of wheel slippage.  With four motors getting power from only one engine, you could at least start the train but you would have a much lower top speed.

It actually does make sense as two DC generators MUST be isolated from each other or else the one with the higher voltage would destroy the other.  Hypothetically speaking, using alternator/rectifier technology, still a few years away after the last E9 was built, two alternators running in parallel on a common AC bus could be rectified to a common DC bus to power all DC traction motors.  Should one alternator fail, the remaining operative alternator would still be able to supply ALL traction motors albeit at reduced currents and lower top speed as you pointed out.  I doubt that Auto-Paralleling circuitry existed back then meaning the alternators would have to be manually paralleled after both diesels were started.  All this is academic as E units were designed to operate at speeds where maintaining all available current to all traction motors simply wasn’t as important as it would be in a freight locomotive frequently operating at high power/low speed.

mlaughlinnyc posted:

It would not make sense to have each generator wired to a single truck.

Well, it may notbmake sense to YOU, but that is EXACTLY how E Uints were designed and manufactured.

 And I fell pretty sure that the throttle did not have two completely separate sets of wiring.

No, the throttle didn't have "two completely separates of wiring", but all the commands from that single throttle went to both power plant electrical cabinets.

  With only one engine, you would not want to have power to only one of the trucks. 

Why not? That is indeed how the twin engined E Units were all designed, as well as the twin engined DD35, DD35A and the biggest DDA40X.

That would have made it impossible to start a heavy train because of wheel slippage. 

Do you have a lot of experience with real diesel electric locomotives? Also, lets remember that we are discussing EMC/EMD E Units, which were designed & developed for PASSENGER SERVICE. They were NOT drag freight locomotives.

With four motors getting power from only one engine, you could at least start the train but you would have a much lower top speed.

Really? How did you come to that conclusion? Again, how much experience do you have with real railroad diesel electric locomotives?

 

prrjim posted:

I think the EMD E units had two MG sets.    Also I think the Baldwin Centipedes did.

When those units were designed, it seems most diesel prime movers of the size that could be used in a locomotive were in the 1000-1500 HP range.    Hence to get a 2000 HP unit, EMD  used two prime movers.   

Diesels with 2000 and greater HP with one MG did not appear until the late 50s or early 60s.

 

Fairbanks Morse Erie Built - 2000 hp Roots blower 10 cylinder 38D-8 1/8 opposed piston prime mover - December 1945.

Alco PA-1 - 2000 hp turbocharged 16V-244 prime mover - June 1946.

Stuart

The light at the end of the tunnel is the headlight of an on coming train!

The FM opposed-piston design was too expensive to maintain (lift out the top-crankshaft with a crane to change out a power-assembly) compared with the EMD 567 as was the underdeveloped Alco 244. Hence the success of the EMD 567 followed by the 645.

Lew

 

Operator of the Plywood Empire Route in the Beautiful Berkshires

Growing old is so much more fun than the only alternative.

Dominic Mazoch posted:

SP did have OP FM's in NM.  Later moved to the Bay Area.  Heard the OP did not like heat and/or sandy conditions.  Then again the OP was the prime mover for some US Navy Subs.

Where it wasn't real warm or sandy...

The FM OP prime movers weren't totally without merit.  The Virginian Railroad diesel fleet was 99.99% FM (They had one GE 44 tonner.)

Rusty

Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in the same shop.  

IC I think was going to buy some FM's and the right to build them?

Dominic,

From what I've read IC was going to order 50 H24-66 Train Master diesels, but a hostile takeover attempt of FM turned them off.

Stuart

The light at the end of the tunnel is the headlight of an on coming train!

Stuart posted:
Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in the same shop.  

IC I think was going to buy some FM's and the right to build them?

Dominic,

From what I've read IC was going to order 50 H24-66 Train Master diesels, but a hostile takeover attempt of FM turned them off.

Stuart

The number I've heard was 75 H24-66's.  I also read somewhere that the IC considered upgrading part of its passenger fleet with FP45's.

Now THAT would've been sumptin'...

Rusty

Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in te same shop.  

IC I think was going to buy some FM's and the right to build them?

It was PRR who wanted rights to build the FM H-24-66 Trainmaster. PRR was also supposedly spying on or poorly trying to spy on EMD and their manufacturing. Pennsy management was really all over the place.

Sam Jumper posted:
Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in te same shop.  

IC I think was going to buy some FM's and the right to build them?

It was PRR who wanted rights to build the FM H-24-66 Trainmaster. PRR was also supposedly spying on or poorly trying to spy on EMD and their manufacturing. Pennsy management was really all over the place.

And just how do you document THAT? Any and all railroad customers could tour the EMC/EMD McCook manufacturing facility any time they requested. In fact, part of the EMD Service Depart Training Center classes INCLUDED an extensive plant tour for EVERY CLASS! 

Rusty Traque posted:
Stuart posted:
Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in the same shop.  

IC I think was going to buy some FM's and the right to build them?

Dominic,

From what I've read IC was going to order 50 H24-66 Train Master diesels, but a hostile takeover attempt of FM turned them off.

Stuart

The number I've heard was 75 H24-66's.  I also read somewhere that the IC considered upgrading part of its passenger fleet with FP45's.

Now THAT would've been sumptin'...

Rusty

Was SOU another who wanted FP45's

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

Dominic Mazoch posted:
Rusty Traque posted:
Stuart posted:
Dominic Mazoch posted:

The OP's worked better in the Bay Area also because they were all grouped in the same shop.  

IC I think was going to buy some FM's and the right to build them?

Dominic,

From what I've read IC was going to order 50 H24-66 Train Master diesels, but a hostile takeover attempt of FM turned them off.

Stuart

The number I've heard was 75 H24-66's.  I also read somewhere that the IC considered upgrading part of its passenger fleet with FP45's.

Now THAT would've been sumptin'...

Rusty

Was SOU another who wanted FP45's

No.

 

Back to the topic:

I guess everyone is now convinced that EMD E-series passenger locomotives contain two diesel-electric power plants, each of which provides electric current to both traction motors of one truck only?  Good.  Then, let's look at how this worked in pre-Amtrak passenger service.

Most mainline passenger trains pulled by E-units had two -- sometimes three -- units.  Union Pacific used up to six units, and SP and Burlington used up to four, at the end of their respective passenger service, because they combined trains on some routes. but two or three was normal elsewhere.

A few (short) top-tier passenger trains and a sizable number of secondary trains ran with a single E-unit.

Here's how this worked in real life.  The three most common en route locomotive failures are:

  1. A high voltage ground fault, usually -- but not always -- in a traction motor.  This condition trips the ground relay, interrupting electric traction current and causing the diesel engine to drop to IDLE.
  2. Low water, which trips the low water alarm and shuts down the diesel engine.
  3. Low oil, which trips the low oil alarm and shuts down the diesel engine.

With a single EMD E-unit, any of these three en route failures would only shut down half of the power, as the other power plant would continue to produce electric current and feed it to the other truck.  The passenger train, which we must remember ran on a schedule, continued moving, and the locomotive could be repaired after the train arrived at its destination, or, could be replaced en route at the next crew change point.  With multiple E-units, the reduction of power would be proportionately smaller, and even less of an issue.

In comparison, if the train was powered by one Alco PA*, or one FP7, or one GP9, and one of the three most common en route failures occurred, then the passenger train and its schedule would be frozen in time, stopped, and blocking a main track.  A rescue would be required.  The schedule, which is the reason the railroad bought the locomotive and cars in the first place, would be ruined, and the trip would have failed to provide the advertised service to the passengers who paid for it to run.

*  With the Alco-GE PA series, the two mechanical shutdowns would stop the train's progress, but the ground fault might not do so.  The high voltage ground would be worked around by resetting the ground relay and using the traction motor cutout switch -- something the EMD unit did not have (or need) -- to cut out either the No.1 or No.2 truck, whichever had the grounded traction motor, by trial and error.  If each truck had been independently cut out and the ground condition was not found by doing so, then the ground would be elsewhere in the system and any of the three en route failures would leave the PA and its train stopped, awaiting rescue.

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

Number 90 posted:

 

*  With the Alco-GE PA series, the two mechanical shutdowns would stop the train's progress, but the ground fault might not do so.  The high voltage ground would be worked around by resetting the ground relay and using the traction motor cutout switch -- something the EMD unit did not have (or need) -- to cut out either the No.1 or No.2 truck, whichever had the grounded traction motor, by trial and error.  If each truck had been independently cut out and the ground condition was not found by doing so, then the ground would be elsewhere in the system and any of the three en route failures would leave the PA and its train stopped, awaiting rescue.

 

Are you suggesting that the E unit engineer did NOT have the ability to reset or isolate traction motors or trucks?  This does not seem right to me, could you expound further?

Because EMD Es have a prime mover/generator dedicated one to each truck a cutout switch would be superfluous. In the case of a ground fault the particular engine/generator/ truck-with-traction-motors would simply fail to load, leaving the other "end" of the unit still working (independent, remember). Thus an E locomotive was it's own protection because virtually ANY breakdown left the other half of the locomotive 100% functional. A beautiful system, simply a take-off on the concept of MU'd multiple locomotive "units" whereby with Es two "units" share a common frame.

 

On edit: I am repeating an already given explanation 

Lew

 

Operator of the Plywood Empire Route in the Beautiful Berkshires

Growing old is so much more fun than the only alternative.

Number 90 posted:

Back to the topic:

I guess everyone is now convinced that EMD E-series passenger locomotives contain two diesel-electric power plants, each of which provides electric current to both traction motors of one truck only?  Good.  Then, let's look at how this worked in pre-Amtrak passenger service.

Most mainline passenger trains pulled by E-units had two -- sometimes three -- units.  Union Pacific used up to six units, and SP and Burlington used up to four, at the end of their respective passenger service, because they combined trains on some routes. but two or three was normal elsewhere...

 

And indeed, Dad took this pic during on one of our (purposeful) layovers in Green River, Wy (c. '61-'65):

        IMG_2989 [1)

Even in those days a lot of horses on the hoof!

Lew

 

Operator of the Plywood Empire Route in the Beautiful Berkshires

Growing old is so much more fun than the only alternative.

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geysergazer posted:

On edit: I am repeating an already given explanation 


Which wasn’t necessary assuming your post was directed at me as I’m aware of how an E unit was set-up electrically.  Nevertheless, your post does NOT answer my question.  When I get home I’ll look through my EMD E7 operators manual and share any relevant information I find.  

Excellent picture!

PRR 5841 posted:
Number 90 posted:

 

*  With the Alco-GE PA series, the two mechanical shutdowns would stop the train's progress, but the ground fault might not do so.  The high voltage ground would be worked around by resetting the ground relay and using the traction motor cutout switch -- something the EMD unit did not have (or need) -- to cut out either the No.1 or No.2 truck, whichever had the grounded traction motor, by trial and error.  If each truck had been independently cut out and the ground condition was not found by doing so, then the ground would be elsewhere in the system and any of the three en route failures would leave the PA and its train stopped, awaiting rescue.

 

Are you suggesting that the E unit engineer did NOT have the ability to reset or isolate traction motors or trucks?

The Engineer could NOT accomplish such a task from his control station. However, the Fireman (remember that railroads still had Firemen back in the days of E Units) could "Isolate" either the front engine generator set or the rear engine generator set, from the respective control panel back in the Engine Room. Although the EMD E Units did not have "Traction Motor Cut-Outs", a resourceful crew member could center the big compressed air operated Reversing Switch and cut out the offending traction motor for the remainder of the trip.

In fact, even on modern units, the Engineer still does NOT have the ability to cut-out a traction motor from his/her operating control station. He/she would have to stop, or the Conductor would have to first Isolate that unit, and then try cutting out traction motors.

 This does not seem right to me, could you expound further?

 

Hot Water posted:
PRR 5841 posted:
Number 90 posted:

 

*  With the Alco-GE PA series, the two mechanical shutdowns would stop the train's progress, but the ground fault might not do so.  The high voltage ground would be worked around by resetting the ground relay and using the traction motor cutout switch -- something the EMD unit did not have (or need) -- to cut out either the No.1 or No.2 truck, whichever had the grounded traction motor, by trial and error.  If each truck had been independently cut out and the ground condition was not found by doing so, then the ground would be elsewhere in the system and any of the three en route failures would leave the PA and its train stopped, awaiting rescue.

 

Are you suggesting that the E unit engineer did NOT have the ability to reset or isolate traction motors or trucks?

The Engineer could NOT accomplish such a task from his control station. However, the Fireman (remember that railroads still had Firemen back in the days of E Units) could "Isolate" either the front engine generator set or the rear engine generator set, from the respective control panel back in the Engine Room. Although the EMD E Units did not have "Traction Motor Cut-Outs", a resourceful crew member could center the big compressed air operated Reversing Switch and cut out the offending traction motor for the remainder of the trip.

In fact, even on modern units, the Engineer still does NOT have the ability to cut-out a traction motor from his/her operating control station. He/she would have to stop, or the Conductor would have to first Isolate that unit, and then try cutting out traction motors.

 This does not seem right to me, could you expound further?

 

Thanks, I suspected the crew MUST have had at least one option.  I ran an F7 once and remember that the generator field had to be turned on (Flashed) by a switch over the engineers side window.  Did the E unit have one or two such switches to turn on their respective generators?

PRR 5841 posted:
Hot Water posted:
PRR 5841 posted:
Number 90 posted:

 

*  With the Alco-GE PA series, the two mechanical shutdowns would stop the train's progress, but the ground fault might not do so.  The high voltage ground would be worked around by resetting the ground relay and using the traction motor cutout switch -- something the EMD unit did not have (or need) -- to cut out either the No.1 or No.2 truck, whichever had the grounded traction motor, by trial and error.  If each truck had been independently cut out and the ground condition was not found by doing so, then the ground would be elsewhere in the system and any of the three en route failures would leave the PA and its train stopped, awaiting rescue.

 

Are you suggesting that the E unit engineer did NOT have the ability to reset or isolate traction motors or trucks?

The Engineer could NOT accomplish such a task from his control station. However, the Fireman (remember that railroads still had Firemen back in the days of E Units) could "Isolate" either the front engine generator set or the rear engine generator set, from the respective control panel back in the Engine Room. Although the EMD E Units did not have "Traction Motor Cut-Outs", a resourceful crew member could center the big compressed air operated Reversing Switch and cut out the offending traction motor for the remainder of the trip.

In fact, even on modern units, the Engineer still does NOT have the ability to cut-out a traction motor from his/her operating control station. He/she would have to stop, or the Conductor would have to first Isolate that unit, and then try cutting out traction motors.

 This does not seem right to me, could you expound further?

 

Thanks, I suspected the crew MUST have had at least one option.  I ran an F7 once and remember that the generator field had to be turned on (Flashed) by a switch over the engineers side window.  Did the E unit have one or two such switches to turn on their respective generators?

No. The Engineer had one set of controls, which was also trainlined to other units MU'ed in the consist. Such as "Generator Field" for instance. Also, no "flashing" was involved.

 

One Generator Field switch per locomotive unit.  

The generator field switch is within reach of the Engineer's seat, (or, on booster units, at the hostler control stand) and only the one on the controlling unit of the consist is closed ("on").  Generator Field switches on trailing switches are open ("off").  As Hot Water pointed out, this is a multiple unit trainlined feature.  It enables excitation of the main generator.

EMD units did not have traction motor cutout switches until the GP18/GP20/SD18/SD24.  Thus, the FP7 and GP7/9 did not have them.  Even after being made available, they were optional, and Norfolk& Western, as an example, did not equip its locomotives with them, in the belief that the Mechanical forces would be forced to fix the electrical ground instead of trying to show the locomotive as available for service.  Mechanical Departments cherish their availability numbers and will cheat in order to make good numbers.

EMD's first traction motor 'cutout switches' were a plastic flag right on the power contactor for each traction motor , which, if rotated 90 degrees, would block that contactor open.  The locomotive unit first had to be isolated, and then 1 traction motor on 4-motor units, or one traction motor on each truck of 6-motor units had to be isolated.  Then the locomotive would be placed on line and -- if the ground fault no longer tripped the relay, the correct traction motor had been found.  This could result in a lot of trying and failing until the correct traction motor was found.  And it always made me nervous to have my hand so close to a large contactor that had been energized with up to 1,400 volts of direct current just a short time earlier.  Later, rotary switches on the Engine Control Panel, on the rear wall of the cab, were provided for cutting out traction motors.  But this was all later, and only the  second generation EMD passenger units such as SDP40 and FP45 and F40PH had them.  E-units, F-units, and early geeps on passenger trains did not have traction motor cutout switches.

The whole point of my last post and this one -- which were not aimed at any particular person, but just intended to bring the conversation back to the very first post on this thread -- is this:

E-units were machines designed to move passenger trains and thereby generate revenue for railroads which purchased them.  They were engineered at EMD with the idea that, if an en route failure should occur, the second on-board power plant would enable the train to seamlessly continue moving toward a forward location where the ailing locomotive could be replaced or repaired, with as little delay to passengers and Railway Express and U S Mail, as possible.  They were not overly complicated.  This technology served its purpose until the end of railroad-owned passenger train service.  Around 1960, EMD equipped its freight and general purpose locomotives with devices that would allow those units to also keep going after a high voltage ground fault had occurred, and get to the next forward shop.  But only E-units* could continue after a low water or low oil shutdown, and this was important to the type of service for which they were purchased.

* Yes, DD35's and other two-engine freight units could also do this, but they were a small percentage of freight units, exceptions to the norm.

Tom

 

Superintendent, High Plains Division (O Gauge) 

The Panhandle & Santa Fe Railway Co.

Lone Star Hi-Railers

Santa Fe, All the Way

mlaughlinnyc posted:
Hot Water posted:
PRR 5841 posted:

Gentlemen,

If one of the two diesel/DC generator sets shuts-down for some reason while pulling a train, does the current produced from the remaining operative diesel/DC generator set go to only one or both pairs of traction motors?  

Each engine generator, and its corresponding electric control circuitry, power ONLY the two traction motors in that truck specific truck. Thus, if one engine generator set "goes down", then THAT truck is unpowered.

I’m assuming that each diesel/DC generator set was permanently wired to one truck (2 motors) and isolated from the other.  

Correct.

The normal diesel locomotive had one generator.  It would not make sense to have two generators each wired to a set of traction motors.  In any slow speed situation, one of two diesel engines would provide enough power for four traction motors.  IF only two motors were powered, the tonnage that could be moved at slower speeds would be halved.

What locomotives do you know had two generators ?

Malcolm Laughlin

Didn't the DD35, DD40ax , the U50c, and the ALCo C855 had two motors and two generators?

member:Golden Spike Club Charter Member

prrhorseshoecurve posted:
mlaughlinnyc posted:
Hot Water posted:
PRR 5841 posted:

Gentlemen,

If one of the two diesel/DC generator sets shuts-down for some reason while pulling a train, does the current produced from the remaining operative diesel/DC generator set go to only one or both pairs of traction motors?  

Each engine generator, and its corresponding electric control circuitry, power ONLY the two traction motors in that truck specific truck. Thus, if one engine generator set "goes down", then THAT truck is unpowered.

I’m assuming that each diesel/DC generator set was permanently wired to one truck (2 motors) and isolated from the other.  

Correct.

The normal diesel locomotive had one generator.  It would not make sense to have two generators each wired to a set of traction motors.  In any slow speed situation, one of two diesel engines would provide enough power for four traction motors.  IF only two motors were powered, the tonnage that could be moved at slower speeds would be halved.

What locomotives do you know had two generators ?

Malcolm Laughlin

Didn't the DD35, DD40ax , the U50c, and the ALCo C855 had two motors and two generators?

Well, to be correct, the DD35, DD35A, DDA40X, and the GE & ALCO "Big Units", had twin Diesel Engines/Generators, while the "motors", i.e. Traction Motors, were all mounted on the axles. 

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