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?
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.
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.
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.
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.
Thanks, guys.
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.
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.
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 taker
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.
Do electric locomotives have battery capacity? Could one run a short distance without catenary or third rail?
It should be noted that the EL-2Bs were 2 unit sets. They could be seperated into 2 single ended units.
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.
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?
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.
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.
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!)
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.