They have the squared off long hood at the rear and the internal machinery arrangement was also shifted a bit forward to help balance the different weight distribution from the steam generating equipment. That’s why they had ballast in the empty steam generator compartment despite it never being intended that they’d have a steam generator.
So I’m not if SD45A is a superior designation since they have all the traits and general specifications of a SDP45, just minus the passenger specific equipment. Even “SD40A”, despite being neither a true SD40 or a SDP40 just minus the steam generating setup, wasn’t an official designation. To EMD, they were still SD40’s despite the longer SD45 frame and their hood and internal machinery arrangement are that of a standard SD40 rather than a SDP40.
EL’s SDP45’s are SDP45’s with all the major modifications inherent with that variation, just not outfitted with the passenger specific equipment onboard. Would be like taking the PH out of F40PH just because it’s on a regional, regeared for freight, and the HEP equipment has been deactivated and removed.
By Jove, on reflection, I think the man’s right! See this example:
which shows both ends of this series of SDP45 together.
Yes, other railroads had flat ends for the steam-generator compartment. The difference might be that they actually intended to put steam generators in them – EL never did; they bought the longer model for the bigger tankage…
MRL has one still in service, upgraded to SD40-2 specifications. KCS has some (I think similarly upgraded, ex TFM and NDEM), some of which were rebuilt to SD22ECOs. Some are scrapped, and a couple may be leasers.
What I meant is they had the bodywork, minus a few openings, that a standard SDP45 did. It isn’t like Illinois Central’s SD40A’s that were stock SD40’s above the frame.
SDP40’s and steam-generator equipped SDP45’s (GN and SP) had the flat ends. To add to the confusion, L&N had some SDP35’s built without steam generators that also had the flat end.
The ONLY SDP-45 I’ve ever seen and worked around was the WC6634 (ex EL) and it looked like someone glued a GP 40 hood on the carbody right behind the radiator flares. (as pictured above) . These certainly did not have a flat end like the SDP40 that MRL was running at the time. The EL SDP- 45s had enough room to walk around the rear hood… the SDP40s were tight and the one I remember had a ladder on the rear instead of a step well.
I never saw an SDP35 but the entire 35 series were my least favorite locomotives because they were electrical maintenance and wiring nightmares.
I became very familiar with the bottom of GP and SD 35 generator pits repairing flashed over brush holders and copper balls between commutator bars. Not a 35 series fan for sure.
I’d bet a case of Black Douglas that neither Don nor anyone else can show you an EL SDP35, period. EL had SDP45’s, not 35’s. (I know, the 3 and 4 keys are right next to each other. [:)])
Even so, though, EL’s SDP45’s don’t really speak to Don’s point, which was about passenger power. EL’s SDP45’s were pure freight machines. (Of course, if you were just yanking Don’s chain for talking about U34CH’s and steam generators in the same breath, then that’s a whole 'nother matter. [:)])
That’s part of it. (So are we into two cases of Black Douglas? We can send one to Mr. Wardale… ;-} )
Interestingly enough, a sort of distraction got going years ago regarding EL 3639 at VMT – describing it as an SDP35. Of course, it isn’t.
I noted a few posts ago that the EL SDP45s were bought for the larger tankage, to give extended range at higher TOFC/COFC speeds, and were not for passenger use.
I do confess to chain-yanking over the U34CHs – it’s so seldom Don Oltmann gets something sideways that I just couldn’t resist. (And it’s been tooooooo long since I had Black Douglas ;-} )
This Burlington Northern example has the squared off hood. Looks like they did make a carbody change that resulted in less space in the rear knowing that these wouldn’t carry a steam generator, allowing for an easier to read numberboard and normal rear steps.
I was under the impression until your post that the only external change was the absence of the boiler air intakes and exhaust stacks.
Wonder why this went this route here with this order instead of something along the lines of the SD40A that was being built right around the same time. Above the frame, the SD40A is a typical SD40 despite the longer frame of the SDP45 for increased fuel capacity. Yet the similar situation here resulted in a modified SDP45 hood instead of a SD45 hood.
I’m sure that pricing had something to do with that decision, especially for a marginal carrier like EL. The SDP45 was pretty close to an off-the-shelf order with a few modifications, mostly sheet metal while the SD40A was non-standard and may have required some extra engineering.
The SDP45(like the GN/BN one picture) were just frame extensions to allow the S/G and the extended fuel/water tank.
The E-L SDP45’s were built to take advantage of the 5000 gallon fuel tank capacity(over the 4000 gallon ‘normal’ fuel tank). This larger tank gave the E-L SDP45’s the range to run unrefueled from NJ to Chicago. The tapered rear end allowed normal rear steps and no need for the anticlimber extension as seen on the BN unit.
The SD40A took advantage of this longer frame as well for a larger fuel capacity, however IC only put the 3,000 hp SD40 above the frame. IIRC, many of these units were manufactured with upgraded electricals and sold to the SOO.
Thanks, but I know what a SDP45 is and why EL ordered them.
What I wondered about since the goals were identical (Larger frame to accommodate increased fuel storage) was why IC’s SD40A’s were straight SD40’s above the frame (Rather than modified SDP40’s) yet the almost simultaneous order for EL’s SDP45’s had most of the unnecessary hallmarks of a SDP45 above the frame.
Going the SD40A route since the goals for both models were the same, they should’ve had the carbody and machinery arrangement of a straight SD45 above the extended frame of a SDP45 on these EL locomotives.
I’m sure it was cheaper this way and I imagine there was a sound engineering reason behind both models as CSSHEGEWISCH says, but I’d love to know just what the particulars were that led to two different routes to accomplish the same thing for their two premier CC freight haulers of the time.
Most of the unnecessary hallmarks of a SDP45 above the frame? Such as? As has been said the rear of the EL SDP45 is different to the SP and GN versions in that it has a pointed end and absolutely zero grilles or outlets, doors, etc needed to access steam generator equipment, the rear steps are also different with the SP and GN versions having vertical ladders at the rear whilst the EL version has the normal EMD stepwell. For all intents and purposes the EL SDP45 IS an SD45 above the frame, just a longer end of the long hood behind the radiators…
An SD40 uses a set of 6 row radiator cores - three double lengths per side arranged in a Vee with three cooling fans. An SD45 uses 8 row cores also arranged in a Vee - which is why they have the “flare” in the carbody. The 8 row cores are a different length than the 6 row cores so it’s not completely simple to substitute one for the other - you pretty much want to stay with the whole assembly for each type.
Leaving the radiator compartment in the same proximity to the engine means no special plumbing needed to make it work. Same piping, structure, couplings, drawings, everything.
Shoving the radiator cab to the back of the long hood would be more work than just plopping some additional sheet metal back there.
The two real questions are:
Why extend the long hood at all on an SDP45? Why not just have a rear “porch”.
Why did EMD push the radiator cab all the way back on the SD40a? Weight balance?
BTW, the SD45-2 solved the problem with the terribly leaky 8 row cores by going to four double six row cores…and there was much rejoicing.
It still has the rear compartment and the general machinery arrangement and weight distribution of a SDP45 which are the major elements of the design that differentiated it from a normal SD45 above the frame. That’s why they carried ballast in that rear compartment to compensate for the missing steam generating equipment.
Illinois Central’s SD40A’s however were stock SD40’s above the frame both in their internal machinery arrangement and their external carbody despite being built on the lengthened frame of the SDP45.
Seems reasonable to be curious why the same goal of increased fuel capacity for the SD40 and the SD45 resulted in two different styles of solutions above the lengthened frames.
Edit: Seems as if I misunderstood. There are indeed some differences. I had read several times over the years that they were identical inside and out above the frame but the close up shots here show otherwise.
