An ABBA question for Geezer

You over rate me - I read a lot and still remember a bit of it. I hope others will add to the following and help me learn if I'm off base.

Yes, the hood model was more flexible that the cab/car body style, especially for freight or mixed work: o The hood units had easy steps at both ends for the brakemen o The hood units were bi-directional, and were often equipped with control stands on both sides facing each direction, so they didn't have to be turned (although many roads had a preference for running them long hood forward in the early years - no worse than looking down the side of a steam loco's boiler, and gave all that mass for crew protection in a collision. In later years, with the advent of low short hoods and wide front windows, and latter wide cabs, running short hood forward has become the norm.) o The doors on the hoods provided easier access for maintenance. o With the advent of second generation units - I believe the GP-30 was the first - the hood allowed for the incorporation of a sealed engine compartment with filtered air supply, leading to a cleaner operating environment for the machinery and the attendant maintenance benefits.

But you're absolutely right - cab units look better, and integrate into a more streamlined appearance with the train. And the RRs realize that, so even after the production of the bulldog nosed F's and E's ceased, we saw the FP45/F45/SDP40F, the F40PH, and other cowl units.

Not to mention the biggest reason.

$$$$$$$$$$$$$

Covered wagons were simply more expensive to build and maintain.

Don

Thanks for all the info guys. I really enjoy learning about this hobby.

Carter

Not that I can claim expertise on this -- but I thought it was actually just forced air through the body and not a sealed compartment that helped keep things clean?

My only experience of EMD products is with their export models, some of our locos have airtight hoods which are slightly pressurised to keep the dust out.

The Alco "Century" series advertised a "pressurized car body" which implies a "sealed" engine compartment.

Don

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The 'sealed' car body is just 'over pressurized' The early GP's like the GP7/9/18/20 had grills on the door panels with oil soaked filters to trap the dust . IIRC, the GE U25B locomotive was the first engine that advertised the central air intake and pressurized car body. Of course, if the hood doors were left open, the whole scheme was compromised. EMD's first fully pressurized unit was the GP30. I am no sure what was Alco's first engine with this feature, but maybe the DL640 or the 'Century' line was their first. EMD's E8 in 1949 sort of played with the concept. The unit took in air behind the cab and and moved it through the car body via ductwork made of false ceiling panels in the roof. I have never verified this, but I read about it in 'Extra 2200 South'. This system did not have a centrifugal air cleaner like later 2nd generation engines. The E8 & E9 always seemed to have features that their brethren never got(like the 'flush' number boards, and integrated fuel tank inside of the water tank), so it is possible that the false panel story is correct. As far as GP's replacing F's - They cost less to build, replacing a power assembly was not an exercise in a dark hell hole of a car body, and did I mention that EMD passed along the savings and charged less for them! Like many of us, I really like the flashy paint schemes on the F's, and I loved to watch a matched set 'snake' it's way through a cross-over or into a siding. I also spent a lot of time chasing SD7's & GP9's plying branch lines and secondary main lines - They all have their place.

Jim Bernier

Trainman wrote:

I recall the old "covered wagons" used the car body as a structural components. The hood units did not. This accounted for some of the added expense of maintenance on the E and F units.

You don't say? Unibody is more expensive than frame-and-panel construction? Hello, Detroit...? Jay CNS&M North Shore Line - "First and fastest"

The F's used the same type of frame as the GPs. The trade-in F's were rebuilt as GPs.

Why did the Santa Fe add steel reinforcement to the frames under the F units that were rebuilt to become CF-7's then? They did it because the F's used a truss frame which is why those type of units are referred to as a covered wagons. The F45's and similar units are not covered wagons because they were not built with truss frames. I suspect you are thinking about the latter type of unit.

Greg,

The F's and E's used a truss frame body construction - very labor intensive to build, thus the high cost. The BL2 also used this type of construction. The GP's use a steel channel frame that runs the length of the locomotive. Basic 'off the shelf' steel materials are used in the fabrication. The frame is welded in a large jig, then a large milling machine drill/mills the motor mounts. Everything else is attached to this structure. When the ATSF converted the F7's into CF7's, they had to add a steel member to the side of the unit to carry the weight, as the truss carbody was now cut away. This is very noticeable as a sort of 'fish belly' piece below the handrails on the walkway.

Jim Bernier

Gregory Procter wrote:

You obviously have NO CLUE about this. GP series diesels have massive undreframes. F-units (and other true "cab" locos) do not; the carboy is a truss, supporting the weight.

While it is true that SOME Fs were rebuilt into GP-style locos (ATSF's CF-7s), you'll note that ATSF had to add massive side girders to support the loco, and they were prone to collapse, causing ATSF to redesign the girder and retrofit older units.

As others have said the frames were completely different. When Fs were traded in the frames were the only bit not re-used. Trucks, engines and electrics would be reconditioned and sold as spares or fitted to GPs.

As a much more recent example of such re-use the UK class 57s are fitted with reconditioned GM engines replacing the old Sulzers they had as 47s.

Keith Make friends in the hobby. Visit Garratt photos for the big steam lovers.

So the assertion by the poster that I responded to was incorrect?

I do remember it being discussed in the BL2 thread that the bodies on them were part of the structure, hence they couldn't be MUed.

Jay CNS&M North Shore Line - "First and fastest"

I really gotta start reading the entire thread instead of just the first before responding to anything...

Jay CNS&M North Shore Line - "First and fastest"

The truss structure may not have been as strong as some thought necessary for MU service. I believe that some of the BL2 did have MU capability. I defer to the B&M experts as they may have more information on this than my recollections.

While some BL2s has MU capability, the frames were just not up to the role. In fact, the original specifications for the model (the BL1) were written under the assumption that they wouldn't be MU'ed, and indicated that an air-activated throttle (which was incompatible with EMD's MU system) should be used. When customers indicated that they wanted MU capability, EMD changed the spec to an electro-pneumatic throttle and made provision for circuitry to permit them to be MU'ed. This was the major difference between the BL1 and the BL2.

The C&O had repeated problems with cracked frames on the BL2s it MU'ed with other locomotives, and like other roads that MU'ed them, got into the habit of patching and welding the cracks as they were discovered. One of its BL2s, #84, spent its last three years in the backshop in Wyoming, Michigan, donating parts for other units after its frame cracked beyond the ability of the welding shop to repair it.

-fm Webmaster of the Pere Marquette Historical Society, at

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