Double-cab electric locomotives

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Double-cab electric locomotives
Posted by Lithonia Operator on Tuesday, November 12, 2019 9:52 PM

Why is it that electic locomotives tend to be double-cabbed, whereas diesels generally are not? I'm thinking mainly about passenger units.

Is there something problematic about turning electrics around? Does it have to do with the positive and negative sides of the catenary? Or a scarcity of wyes with catenary? 

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Posted by MidlandMike on Tuesday, November 12, 2019 11:02 PM

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.

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Posted by Erik_Mag on Tuesday, November 12, 2019 11:34 PM

The Milwaukee Little Joe's were built double ended, but the Milwaukee blanked off one cab and put addional switching gear in the cab space.

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Posted by CSSHEGEWISCH on Wednesday, November 13, 2019 7:05 AM

The second cab in the Little Joes was blanked about the time that MILW started running them in pairs.  I'm not sure if the two events are related.  South Shore's Little Joes retained two operating cabs until their retirement.

I don't know if this counts, but Virginian's postwar EL-2B's were doublecabs in freight service.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by BaltACD on Wednesday, November 13, 2019 7:56 AM

CSSHEGEWISCH
The second cab in the Little Joes was blanked about the time that MILW started running them in pairs.  I'm not sure if the two events are related.  South Shore's Little Joes retained two operating cabs until their retirement.

I don't know if this counts, but Virginian's postwar EL-2B's were doublecabs in freight service.

Remember the Little Joe's were not BUILT for USA operation - they were built for Russia and when the Cold War broke out they were not allowed to be delivered to Russia.

The cost of equipping the 2nd cab with all the things required to be a operating cab is the reason for only having one cab equipped for operation.  Remember a number of carriers (post 1st Gen units) had the manufacturers build 'B' units without operating controls to save money.

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Posted by daveklepper on Wednesday, November 13, 2019 8:57 AM

The PRR E-33 (Former Virginian, N&W, NYNH&H and later Conrail) and E-44 freight electrics were single-cab.  Electrics require even less maintenance than diesels, and passenger electrics can easily reverse at the passenger terminal for a reverse trip without a light move to a yard.  So it makes sense to equip the electrics with two cabs, rather than having loop tracks, wyes, or turntables at the passenger terminals themselves.  Pennsylvania Station's Sunnyside yard makes that exception the only one.  Think of GG1s reversing at Harrisburg or Washington, DC or at Wilmington for St. Charles trains, or South Amboy for Bay Head Junction trains.  Today Amtrak at Boston and Washington and Philadelphia.

Diesels need servicing, even if just refuling, so a trip to a yard with loop, wye, or turntable, either light or with the passenger equipment, is usual.

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Posted by Lithonia Operator on Wednesday, November 13, 2019 10:11 AM

Thanks, guys.

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Posted by Overmod on Wednesday, November 13, 2019 10:41 AM

Lithonia Operator
Why is it that electic locomotives tend to be double-cabbed, whereas diesels generally are not? I'm thinking mainly about passenger units.

The simple answer here is that passenger units are usually streamlined, and not run in married pairs.  So a single-end engine would have to be repeatedly turned unless equipped specifically for push service and used with a dedicated cab car.  That's not at all characteristic of typical passenger service with loose cars.

It's interesting that, unlike the situation in Australia (for example), this logic was stillborn with 'diesel equivalents'.  Jersey Central had the equivalent of a 'transfer' Baldwin with two streamlined end cabs instead of one center cab with hoods... but that approach did not catch on, and it may be instructive to consider why not.

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Posted by Overmod on Wednesday, November 13, 2019 10:47 AM

Lithonia Operator
Is there something problematic about turning electrics around? Does it have to do with the positive and negative sides of the catenary? Or a scarcity of wyes with catenary? 

Almost all practical electrics with overhead wire run the traction 'return' (whether AC or DC) through the track, so the only way 'handedness' would matter would be if you turned them upside down.  Reversing is handled internally, not by 'reversing polarity' between overhead and return (which if you think about it would screw up any other locomotives operating in a given power block)

Scarcity of wyes 'nearby' is certainly a consideration; another is the time (including crew time and compensation type) that would be involved with wying as opposed to changing cabs.  An example is the engine change at Perth Amboy, which would have involved dismal multiple moves several miles to turn engines, whereas 'pairs' of E units could easily move off and then 'take the next train' back when it arrived.

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Posted by Flintlock76 on Wednesday, November 13, 2019 11:03 AM

Overmod

 

 
Lithonia Operator
Why is it that electic locomotives tend to be double-cabbed, whereas diesels generally are not? I'm thinking mainly about passenger units.

 

The simple answer here is that passenger units are usually streamlined, and not run in married pairs.  So a single-end engine would have to be repeatedly turned unless equipped specifically for push service and used with a dedicated cab car.  That's not at all characteristic of typical passenger service with loose cars.

It's interesting that, unlike the situation in Australia (for example), this logic was stillborn with 'diesel equivalents'.  Jersey Central had the equivalent of a 'transfer' Baldwin with two streamlined end cabs instead of one center cab with hoods... but that approach did not catch on, and it may be instructive to consider why not.

 

Two things with those Jersey Central double-ended diesels.

First, and my opinion, they were probably just a little ahead of their time, at least here in the US.  Look at those NOHAB/GM double-end diesels in Europe, they liked the concept there just fine.  Here's an example...

https://www.flickr.com/photos/n4fade/17335202459  

Second, on those Baldwin "Jersey Januses" as they've been called the concept was good but the execution was poor. (Jersey Central had to go with Baldwin, neither GM or ALCO were interested in a custom job like that.)  Long story short they turned out to be maintanance headaches, not good for a long service life.  The word got around so when the CNJ tried to sell them off there were no takers.  

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Posted by rcdrye on Wednesday, November 13, 2019 2:55 PM

VGN/N&W/NH/PC/CR E33s and PRR/PC/CR E44s all had dual controls, like many contemporary diesel hood units.  They could be operated long hood forward.

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Posted by DSO17 on Wednesday, November 13, 2019 5:00 PM

rcdrye

VGN/N&W/NH/PC/CR E33s and PRR/PC/CR E44s all had dual controls, like many contemporary diesel hood units.  They could be operated long hood forward.

 

     While the E44s had controls on both sides of the cab, the E33s had only one control stand set up to run short hood forward.

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Posted by Lithonia Operator on Wednesday, November 13, 2019 9:18 PM

Do electric locomotives have battery capacity? Could one run a short distance without catenary or third rail?

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Posted by MidlandMike on Wednesday, November 13, 2019 10:01 PM

CSSHEGEWISCH
I don't know if this counts, but Virginian's postwar EL-2B's were doublecabs in freight service.

It should be noted that the EL-2Bs were 2 unit sets.  They could be seperated into 2 single ended units.

https://www.railpictures.net/photo/387700/

 

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Posted by Erik_Mag on Wednesday, November 13, 2019 10:56 PM

Lithonia Operator

Do electric locomotives have battery capacity? Could one run a short distance without catenary or third rail?

 

Several electric switching locomotives were equipped with batteries in the 1925 to 1950 era, typically interurban style locomotives. Almost all of these ran off of 600V. There were a few tri-power (battery, diesel and electric) locomotives built around 1930, notably for the NYC.

Adding battery capacity should be easier now as the latest AC inverters will operate quite nicely with a fixed DC link (AKA bus, or power rails) voltage.

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Posted by blue streak 1 on Wednesday, November 13, 2019 11:08 PM

The electrics did need to go to servicing for the steam lines.  That would be for both water and fuel oil for the boiler heat. So the GG1s and NH jets.  How did Milwaukee handle the need for steam?

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Posted by CSSHEGEWISCH on Thursday, November 14, 2019 6:46 AM

Erik_Mag
 

Several electric switching locomotives were equipped with batteries in the 1925 to 1950 era, typically interurban style locomotives. Almost all of these ran off of 600V. There were a few tri-power (battery, diesel and electric) locomotives built around 1930, notably for the NYC.

Tri-powers were built for NYC and DL&W, the Lackawanna units had a pantograph instead of third-rail shoes.  A dual-power of similar configuration was built for Rock Island for passenger switching at La Salle Street Station.

Several interurbans had battery-electric steeplecabs, most notably North Shore 455 and 456.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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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.

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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!)

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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.

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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.

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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.

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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

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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

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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
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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?

 

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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
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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...

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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. 

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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!)

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