Trains.com

Double-cab electric locomotives

5937 views
45 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Wednesday, September 30, 2020 5:09 PM

Very interesting video, another example of a moving picture being worth thousands of words.

Note that this is still comparably low-voltage; if division as shown is into '30-volt arcs' this is no more than about 277V.  Presumably there is a version for up to ~480V, but you're starting to get into the range even there where a combination of (induced by arc current) magnetic field and air blast is desirable to clear the conductive plasma from between the opening contacts.  How the energy is dissipated from the extended plasma is another matter, one of more than trivial concern in 'arc flash' safety.

  • Member since
    July 2008
  • 1,758 posts
Posted by rdamon on Wednesday, September 30, 2020 11:03 AM

  • Member since
    September 2002
  • From: ShelbyTwp., Michigan
  • 1,138 posts
Posted by SD60MAC9500 on Wednesday, September 30, 2020 9:40 AM
 

MidlandMike

Some freight motors were single ended, such as the PC E-33 and E-44, and the Black Mesa E-(60?).  Most of the US double enders were either historic, or modern passenger units that are reversed often.

 

Add BC Rails GF6C to the single cab club. Yes the 1st gen E60C were single cab. The E60C-2 was the only modern domestic freight double cab electric built. Seven are still in operation on the Desert-Western located in the Uinta Basin.

 
Rahhhhhhhhh!!!!
  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Tuesday, September 29, 2020 6:25 PM

PATTBAA
You don't "start" a locomotive as you do an engine; you advance it from zero speed to full-speed.

Actually this is the definition for any voltage-controlled electric motor, and technically includes bringing up a rotary converter.  It can be confusing to those only familiar with internal combustion to read about 'starting resistances' too.

I was fortunate to have people explain to me both on IRT subway equipment and on PRR MP54s how to get smooth physical car starts from rest and then controlled acceleration with restricted tap control.  It's something of an art.

Incidentally there is more required when opening HV contactors than when initially closing them: when you look at the action of blowout coils, arc chutes, etc. you will gain a greater appreciation for the practical joys of switching heavy inductive loads...

  • Member since
    January 2019
  • 1,024 posts
Posted by Erik_Mag on Tuesday, September 29, 2020 2:46 PM

Overmod

It was my opinion years ago that 5000kV operation with twin motors (the armatures in series as in the Grass Valley experiment) would have been a sensible alternative -- this was still the era of larger twin motors that didn't handily fit between the backs of wheels at standard gauge, like the GG1 motors or the 428As that followed, but still a known and good alternative.

Sounds like you're proposing a remake of the Westinghouse "Quills" with 1250V motors instead of the 750V motors used. One issue with running a bunch of motors in series is insulating the motor windings for 5kV and figuring out how to prevent arcing between the brusholders and motor frame.

OTOH, some of the Thury system implementations were running 75kV or more with lots of motor's in series, albeit the motors were on insulated mounts and had insulated shaft couplings.

Is there a reason why Batchelder bipolar motors couldn't run effectively on 2500kV apiece in series under load?

The bipolar motors were lacking interpoles, so it would have been a challenge to go higher than the 1000V on the Milw Bipolar's. Note that traction motor voltage pretty much topped out at 600VDC prior to interpoles. IIRC, the motors for the M-G sets were 2 pole design to allow enough commutator bars between brushes, but had interpoles to improve commutation.

Note that the 5kV proposal made sense with the existing traffic and number of locomotives. An increase in traffic would have lead to a higher cost for the 5kV locomotives than with the 3kV locomotives.

  • Member since
    August 2020
  • 27 posts
Posted by PATTBAA on Tuesday, September 29, 2020 1:51 PM

Because of the weight of a single  11,000 volt traction-power transformer, the EP-1 was equipped with two which were "auto-transformers" , an auto-transformer a single- winding design. Refer ( via hathitrust ) to the Street Railway Journal ,Volume 30 , Aug. 1907 , pags 278-285 , for an illustration of the transformer-motor connections thru "unit-switch" contacts with "blow-out" coils.You don't "start" a locomotive as you do an engine; you advance it from zero speed to full-speed.

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Monday, September 28, 2020 11:27 PM

Erik_Mag
OTOH, Anaconda was interested in promoting electrification as a market for copper.

If I remember correctly, it's a bit deeper than just board representation: some of the finance of the PCE came from people or entities specifically concerned with 'maximizing the amount of copper' in the construction.  I have my suspicions that the fancy doubled trolley structure stems at least in part from some behind-the-curtain input into engineering.

It was my opinion years ago that 5000kV operation with twin motors (the armatures in series as in the Grass Valley experiment) would have been a sensible alternative -- this was still the era of larger twin motors that didn't handily fit between the backs of wheels at standard gauge, like the GG1 motors or the 428As that followed, but still a known and good alternative.  

Is there a reason why Batchelder bipolar motors couldn't run effectively on 2500kV apiece in series under load?

  • Member since
    January 2019
  • 1,024 posts
Posted by Erik_Mag on Monday, September 28, 2020 11:19 PM

You are remembering coorectly about the Milw board, but don't think it had much to do with the 3kV vs 5kV decision. OTOH, Anaconda was interested in promoting electrification as a market for copper.

  • Member since
    September 2011
  • 5,290 posts
Posted by MidlandMike on Monday, September 28, 2020 10:36 PM

Erik_Mag
The savings in copper with 5000VDC were eaten up by the increased cost of the locomotives. It was also thought that the investment in copper was easier to salvage than the investment in locomotives.

Am I remembering correctly that someone from Anaconda sat on the MILW Board, so choosing the more copper alternative may have been preferred?

  • Member since
    January 2019
  • 1,024 posts
Posted by Erik_Mag on Sunday, September 27, 2020 10:58 PM

Overmod

There were experiments to run DC motors in permanent series on 5000Vdc just before WWI, but the 'big savings' weren't worth the fun.

GE had investigated the use of 5000VDC for the Milwaukee, with the overall costs for the 3000VDC and 5000VDC being about the same. The savings in copper with 5000VDC were eaten up by the increased cost of the locomotives. It was also thought that the investment in copper was easier to salvage than the investment in locomotives.

There has been some work done in replacing standard iron core distribution transformers with switching power supplies acting as a transformer. High voltage side was 14.4kV and it would seem that such a beast could be adapted for 14kVAC or 20kVDC catenaries.

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Sunday, September 27, 2020 6:27 PM

Interesting that at least some hydro generators are kept motored to reduce effective cold start times; I had thought it was only done for synchronization or to reduce shock if the supply piping had high head or other characteristic mitigating against stable acceleration in ~60-90sec.  Keeping them spinning at some speed would also mitigate need for high-pressure prelubing of the step bearing during the early stage of spinup.

Interesting to see the professional take on this.

  • Member since
    December 2007
  • From: Georgia USA SW of Atlanta
  • 10,357 posts
Posted by blue streak 1 on Sunday, September 27, 2020 4:10 PM

Discussions of motor voltages can best be addressed by using the ultimate motor voltage / output voltages of hydro electric generators .  Most generators are motored continously at speed so can immediately become generator as soon as water power is applied.

https://www.gepowerconversion.com/sites/gepc/files/product/Hydro%20Generator%20Brochure.pdf 

https://en.wikipedia.org/wiki/Hydroelectricity 

20,000 volts

https://www.brighthubengineering.com/power-plants/45558-electric-power-generators-how-they-work/

 

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Thursday, September 24, 2020 10:11 AM

PATTBAA
... "connecting the motors to the transformer power is only used at starting." Then what are the motors connected to for "running"?

I suspect this is a construction artifact being explained leaving fundamental electrical control out.

No practical railroad motor runs effectively on 11kV power directly, even larger 'industrial' ones adapted for jackshaft drive.  (There were experiments to run DC motors in permanent series on 5000Vdc just before WWI, but the 'big savings' weren't worth the fun).

Accordingly there is 'something' that steps the 11kV down to whatever the motors use for continuous running.  That will likely be a transformer, and if it has no speed-regulation taps in its winding structure it would be connected and disconnected via contractors (probably with hefty blowout and arc chutes!!).  The implication from the language is that the six stages of tap are on a separate 'starting' transformer that is sized for acceleration and then 'switched out' for the running one once the train has gathered momentum.

In my hymble opinion such a design would be transitory, perhaps even experimental, and perhaps limited by available materials or equipment.  Certainly the EP-3 and GG1 used multiple-tap control on their main transformers -- in part through the miracle of Pyranol.

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 12,456 posts
Posted by CSSHEGEWISCH on Thursday, September 24, 2020 10:00 AM

Chicago Surface Lines conducted coasting experiments on a line through congested commercial areas where it was considered difficult to coast.  The experiments did show reduced power consumption and coasting instructions were extended systemwide as a result.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    June 2002
  • 17,868 posts
Posted by daveklepper on Thursday, September 24, 2020 3:44 AM

Nonsense.  All AC electrics pass power through transformers under all conditions.

The word "taps" was missing.   Transformer taps are only used on acceleration?

Probably also nonsense, unless the railroad had a rule:

"Once up-to-speed, full power or coast."  The IND New York subway had that rule at one time.  Supposedly saved power.

 

 

 

  • Member since
    August 2020
  • 27 posts
Posted by PATTBAA on Friday, September 18, 2020 9:33 PM

"Tap changing which is how speed control on 'modern' NH AC (electric) locomotives was done."--The EP-1 prototype was operational in 1905 (I have the photo).There were only six "steps" , or "notches" for AC acelleration, far less than for D.C. For D.C. the traction-power motors could be connected to only one voltage-value, the 3rd rail voltage, which required for starting a two-motor series connection in series with resistors.For A. C. acelleration the motors were connected to six "taps" off the 11,000 volt transformer winding, each connection with a specific voltage-value.----"connecting the motors to the transfomer power is only used at starting." Then what are the motors connected to for "running"?.

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Friday, September 18, 2020 1:01 PM

There is a great deal more involved in constructing two cabs on a locomotive than just the method of driving tap changing (which is actually how speed control on the modern New Haven AC locomotives was done, just as on the derivative GG1s).  If you think about it, there are two full sets of brake gear, cab signals, lights, heaters, and other mechanical gear, even before you get into fabricating the cab structure with windows and collision bracing, and account for the diminution in usable length for packaging internal locomotive components or balancing weight distribution.

Connecting the motors to the transformer output power is a different function entirely, and it is only used at starting, and if for some reason it becomes necessary to isolate a motor (for failure).  To my knowledge none of these locomotives have 'transition' as diesels do, but even if so this would be for series/parallel reconnection, which has little to do with actual command of the speed of the motor (either a DC voltage-controlled motor via full-wave rectification or one of the 'universal' motors running directly on the 'tapped' AC.

It was my impression that the accelerating resistances on the New Haven 'universal' motors running on DC were comparatively few, and as a result the actual balancing speeds were about the same as on the MU equipment -- which is to say, not very many.  AC MU equipment on PRR was not much better -- I think you had only a couple of latching positions either side of 'neutral' and you used the brake for finer speed control if you needed to.  (Watch someone who really knows how to drive older subway trains for the DC MU controller equivalent; e.g. how to make smooth starts!)

  • Member since
    August 2020
  • 27 posts
Posted by PATTBAA on Friday, September 18, 2020 12:08 PM

"Why is it that electric locomotives tend to be double-cabbed?." The control power on the NHRR"s first electric, the EP-1 , was 14 volt battery-power , so a controller at each end was not at all difficult.The controller was designed with seperate "Fwd" / "Rev" levers ,the reverse lever romovable which made that contr oller in-operative.The control leads connected to electro-pneumatic valves. When the controller "selected" a valve , 80 psi pressure would force-close a contact connecting a motor-lead to the traction power.Four traction-power motors = 16 motor-leads connected to multiple contacts , both A.C. and D.C. For A.C. acelleration the motors were switched to succesively higher voltage values; for D.C. acelleration they were switched to succesively lower resistance values. 

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Friday, November 15, 2019 8:28 PM

I was referring to the electric boilers, not to the DD1s themselves.  

It's interesting that the DD1s were so successful for a variety of reasons that were not preserved in the L5s, which were some of the all-time dogs of electric engine design.

Then you have the O (by analogy to steam E), P5 (by analogy to K4) and R (basically enlarged P) approach to AC motors ... not 'all there' for passenger work, although the two Os in multiple did a pretty good approximation of an eight-coupled steam locomotive.  

All was redeemed by the GG1, so good that most of the postwar refinements in electric design were bypassed right to the '60s...

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 12,456 posts
Posted by CSSHEGEWISCH on Friday, November 15, 2019 12:00 PM

Some of the DD-1's were replaced by various permutations of the L-5.  Excess DD-1's were transferred to LIRR.  The remaining PRR DD-1's and L-5's were replaced by P-5's when the New York Terminal Zone was converted to AC catenary.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Friday, November 15, 2019 10:25 AM

Erik_Mag
The PRR DD1's get the prize for most unusual steam generator as it was heated by electricity (600V traction power).

But as I recall these didn't last long ... and didn't we decide they were replaced with ... nothing?

 

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 12,456 posts
Posted by CSSHEGEWISCH on Friday, November 15, 2019 6:48 AM

A total of six E2b's were built.  They had AC motors and could operate in multiple with P5's.  The Westinghouse units (E2c and E3b) were early rectifier units.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    September 2011
  • 5,290 posts
Posted by MidlandMike on Thursday, November 14, 2019 9:35 PM

GE also built for the PRR the E2b, a 2 unit set of AC electric streamlined (single) cab units.

https://www.classicstreamliners.com/lo-prr-e2b.html

  • Member since
    September 2011
  • 5,290 posts
Posted by MidlandMike on Thursday, November 14, 2019 9:18 PM

In the 1950s Westinghouse built for the PRR a couple of 2 unit rectifiers (E3b and E3c) each as a pair of streamline (single) cab units.  They could also be seperated as single units.

https://commons.wikimedia.org/wiki/File:PRR_E3b.jpg

https://commons.wikimedia.org/wiki/File:PRR_E3c.jpg

  • Member since
    September 2011
  • 5,290 posts
Posted by MidlandMike on Thursday, November 14, 2019 8:53 PM

Erik_Mag
The B.A.&P. electrics avoided steam generators by running 2400VDC to the passenger cars for electric heat - blower motors for forced air circulation used the heating strips as dropping resistors.

After the BA&P replaced the passenger trains with mixed trains composed of a long string of ore cars folowed by a combine, they installed stoves (IIRC coal) in the combine.

  • Member since
    January 2019
  • 1,024 posts
Posted by Erik_Mag on Thursday, November 14, 2019 12:50 PM

Overmod

As I recall, the EP1s and EP2 bipolars were built with heavy-oil-fired steam boilers.  EP1s apparently had one per unit; the bipolar had its in that 'center' section between the articulated ends.  

The two passenger Joes (E20 and E21) had more modern steam generators, probably Vapor-Clarkson fired on diesel oil, and the bipolars got similar units in the 1953 rebuilding.  I wish I could tell you the precise model number and show pictures, but someone will rectify that (ahem! ahem!)

The Westinghouse built EP-3's (AKA Quills) also had a heavy oil fired steam boiler which is described in a 1920 issue of "The Electric Journal". The EP-4's (passenger Joes) had the steam generator installed in the unused cab - info might be in Holley's book on the Milwaukee.

The PRR DD1's get the prize for most unusual steam generator as it was heated by electricity (600V traction power). The B.A.&P. electrics avoided steam generators by running 2400VDC to the passenger cars for electric heat - blower motors for forced air circulation used the heating strips as dropping resistors.

  • Member since
    June 2002
  • 17,868 posts
Posted by daveklepper on Thursday, November 14, 2019 11:10 AM

Blue Streak:  Both GG1s and New Haven passenger electrics were inspected and had water and heater oil and sand, and lightbulbs on a time-passed-basis, daily.  The GG1s at Sunnyside, where they would use the loop if convenient; the New Haven's at "Motor Storage" right by the New Haven passenger station without any loop or wye.  Usually, two, three, or in the case of Penn - South Amboy, four round trips could take place between servicing.  At Washington Union, Wilmington, Harrisburg, South Amboy, and Hunter, simple reversal was facilitated by the double cabs.  Ditto New Haven power at Grand Central Terminal and Pennsylvania Station, as well as Motor Storage at New Haven.

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Thursday, November 14, 2019 9:37 AM

blue streak 1
How did Milwaukee handle the need for steam?

As I recall, the EP1s and EP2 bipolars were built with heavy-oil-fired steam boilers.  EP1s apparently had one per unit; the bipolar had its in that 'center' section between the articulated ends.  

The two passenger Joes (E20 and E21) had more modern steam generators, probably Vapor-Clarkson fired on diesel oil, and the bipolars got similar units in the 1953 rebuilding.  I wish I could tell you the precise model number and show pictures, but someone will rectify that (ahem! ahem!)

  • Member since
    September 2003
  • 17,153 posts
Posted by Overmod on Thursday, November 14, 2019 9:22 AM

Erik_Mag
There were a few tri-power (battery, diesel and electric) locomotives built around 1930, notably for the NYC.

Erik knows this, but some of you might not.  The tri-powers were obligate battery locomotives.  Both the internal-combustion generation and the third-rail connection did nothing but charge the battery bank.  

Some people have been fooled by the little roof pantograph that is needed to keep third-rail straight electrics from stalling in a gap of corresponding length.  If a tri-power has one there it's to facilitate charging under any condition, not to keep the engine moving on third-rail DC.

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

Newsletter Sign-Up

By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy