E and F units What are the differences

[wjstix]

Question: Weren't only FB units equipted with steam generators until the intruduction of the FP-9?

Yes, only it was the FP-7; the FP-9 came later. It's possible some railroad somewhere found a way to jerry-rig a small steam boiler and water supply into an A unit, but generally the water and steam generator went into the B unit because it had a lot more room (no cab, no nose, etc.) than an A unit.

[dehusman]

GM considered 4 units to be ONE locomotive but conceded that there were times when just two units might suffice.  Contemporary railroading also thought of the sets as one locomotive, thus the locomotive number plus A, B, C, or D to designate the individual unit.  It wasn't until much later that railroads discovered the advantage of breaking up the sets.

They recognized the value of individual units right away.  The reason the engines were sold as sets was because of crew agreements.  The fear was that if the engines were numbered individually the unions would require a separate engine crew on each unit.  So the engines had one number and the "pieces" were sub-lettered.  EMD even went so far as connecting the FTA & FTB with drawbars so they were physically one unit.  When it was sorted out that an additional engine crew would not be needed the units started being individually numbered and used in mixed sets.

Dave H.

[jktrains]

They were also sublettered A B C D so that maintenance crews knew which unit in a set to work on.  Consider the work order than read "Bad traction motor in 3rd axle on unit 145" which was an ABBA set of F units.  Which 3rd axle?  Also the reason why B units had a designated 'F' or front.

[R. T. POTEET]

Question: Weren't only FB units equipted with steam generators until the intruduction of the FP-9?

The purpose of the FPs was to provide A-units with enough steam generator capacity to be used singularly on passenger trains. All A-units could be - and many were - equipped with steam generators but their capacity was so limited as to restrict them to short train or short distance operation. If you encounter a photo of a conventional A-unit lugging a substantial length passenger consist it is a sure bet that that train ain't goin' very far!

Adding a B-unit with its increased water capacity increased your capabilities dramatically. When you see a photo of an FP lashed to a B-unit the B-unit was, in many cases, there strictly for the tractive effort. 

[riogrande5761]

To all:
FL9's were originally designed for long distance passenger trains for carrying a lot of water (which was the limiting range factor, not fuel back then).  That's why they had a 5th axle...to handle all that water weight.  No one bought any.  Then the NH came knocking, and EMD dusted off the FL9 plan, removed the water tanks, added 3rd rail shoes and an electrical cabinet, and presto!  A Dual-mode loco is born.

 

Just curious...  would it have been more expensive to adapt a design using a specialized 3 axle truck or non conventional F unit chassis, rather than using an existing model adapted to the 3rd rail shoes, like the FP7 etc?

Question: Weren't only FB units equipted with steam generators until the intruduction of the FP-9?

The purpose of the FPs was to provide A-units with enough steam generator capacity to be used singularly on passenger trains. All A-units could be - and many were - equipped with steam generators but their capacity was so limited as to restrict them to short train or short distance operation.

Model Maker,

B units were equipped with steam generators before and after the introduction of the FP7.  As Poteet said, the FP7 was just a longer F7A so that a larger water capacity could be added for F7's which might singly lead a passenger train and not rely on the B unit steam generator for passenger heat.  Standard length F7A's were in a few cases delivered with steam generators in them (which is what the Athearn "Globe" F7A shell was based on - it has steam generator details on the rear roof).

If you encounter a photo of a conventional A-unit lugging a substantial length passenger consist it is a sure bet that that train ain't goin' very far!

Or it is summer time!  In my Rio Grande books, there are a number of photo's of non steam generator equipped F units leading passenger trains and they went substantial distances.  But being summer weather, steam generators were sometimes not required.

[Autobus Prime]

They were also sublettered A B C D so that maintenance crews knew which unit in a set to work on.  Consider the work order than read "Bad traction motor in 3rd axle on unit 145" which was an ABBA set of F units.  Which 3rd axle?  Also the reason why B units had a designated 'F' or front.

jk:
From what I hear,the work orders in the early diesel days would often have been "Unit 145D is actually still running." That may have been steamish sour grapes...to some degree. }:)

Santa Fe had an unusual lettering scheme. Instead of A B C D, they used L (for Lead) then A B C.

[In] summer weather, steam generators were sometimes not required.

Some railroads did use steam-jet air conditioning systems. I think Santa Fe might have.

[riogrande5761]

They were also sublettered A B C D so that maintenance crews knew which unit in a set to work on.  Consider the work order than read "Bad traction motor in 3rd axle on unit 145" which was an ABBA set of F units.  Which 3rd axle?  Also the reason why B units had a designated 'F' or front.

jk:
From what I hear,the work orders in the early diesel days would often have been "Unit 145D is actually still running." That may have been steamish sour grapes...to some degree. }:)

Santa Fe had an unusual lettering scheme. Instead of A B C D, they used L (for Lead) then A B C.

Indirectly sour grapes maybe.  From what I've read, F unit's were given a single number by the railroads initially because they feared unions would require them to pay an engineer and man each locomotive in the consist if they were numbered individually.  In the steam era, trains requiring more than one loco to power a train (especially mountains) required a crew for every locomotive by necessity and convention.  Suddenly you have during the diesel era, more than one locomotive but all the trailing units can be controlled from the lead unit.  This was a paradigm shift in crewing and operations.  Since unions had not adapted to this new practice, an FABBA set was given one number and ABCD sub letters, to have one crew with no disputes from the unions.  As time went by and that somehow was no longer a concern, the individual power units were assigned individual road numbers and in time, broken up and mixed as needs warranted.

[In] summer weather, steam generators were sometimes not required.

Some railroads did use steam-jet air conditioning systems. I think Santa Fe might have.

That may have been true for the Rio Grande as well.  In summer diesels were sometimes assigned to passenger trains or special movemetns (eg boy scout jambouree's) with no steam generators.  But passenger cars may have had means of cooling as you stated.  I'll have to check my books but I recall some mention of old heavy weight passenger cars being rebuilt/modernized in the 1940's both cosmetically (stream styling) and for creature comforts.

[Medina1128]

Every once in a while, they have a category about drag racing on Jeopardy (I love to amaze my friends and family), since I dedicated a lot of time and energy to the sport many years ago. I can't wait for them to have one on model railroading so I can use ALL the things I've learned in the Forum. You guys are great!

[Paul3]

riogrande5761,
I'm not quite sure what you're asking.  I know the NH did attempt to convert a DL-109 to a dual-mode loco, but the weight restrictions of the Park Ave. Viaduct in NYC prevented it from even being built.

EMD picked the FL9 design to convert because it had plenty of room (without the water tanks) and it met any possible weight restrictions with that 5th axel.  It also didn't need much for "new" design work, other than adding 3rd rail shoes to the rear truck, adding some DC accessories, and some extra controls.

Paul A. Cutler III
************
Weather Or No Go New Haven
************

[steemtrayn]

Back to the original question...the difference between an E and an F unit...

In my opinion, the most important difference is the length, as this will determine how well the engines look on model size curves. The F is the short one.

 

[tgindy]

In my opinion, the most important difference is the length, as this will determine how well the engines look on model size curves. The F is the short one.

E Units are like "stretch limos" of F Units.