SD 40

[phil55]

What are the main spotting features between an SD 40 and an SD 40-2?

[wazzou]

Water sight glass on the engineer's side long hood for one.  Possibly some dustbin hatches or fans differ but I can't say for certain.

[C855B]

A semi-reliable spotting feature is a longer taper with an access hatch on the front of the dynamic brake blisters, for the extended (low-speed) dynamic brakes. While Dash-2's could be ordered the old style non-extended brakes and the regular blister (since the GP35), most roads bought the extended version. Anyway, the presence of the extended brakes is 99.99% Dash-2.

There were other visible features on the Dash-2 line that did not appear on the previous versions, such as snoot noses (110"?). IOW, the presence is positive ID of a Dash-2, but absence does not mean it's a non-Dash-2.

That's pretty confusing, but I hope you catch the concept. 

[Mark5]

Much larger "porch" on either end of the SD40-2.

Flexicoil trucks vs HTC trucks on the Dash 2.

[C855B]

Didn't IC have a handful of regular SD40's on SDP frames, and therefore also had longer porches? I think they did that for the longer fuel tanks, like EL did.

[lock4244]

Didn't IC have a handful of regular SD40's on SDP frames, and therefore also had longer porches? I think they did that for the longer fuel tanks, like EL did.

SD40A's... 5000 gal fuel tanks IIRC. Went to CP, the buyer of old junk.

IC also had at least one SD40X, IC 6071... SD40 guts crammed onto an SD35 frame.

SD40-2 is ~3' longer than an SD40, which does make a significant visual difference when comparing side by side.

[Spikre]

 
  think it was GM&O with the SD40X,but became ICG later.
  IC had the Original SD45,former EMD Test and Demo unit.
  seem to think IC had the original GP40X on the GP35 frame ?
  not to be confused with the late 70s GP40Xs sent to different
  roads for Data by EMD.
  something soured Santa Fe on the GP40Xs,and they changed
  a Follow Up order to SD40-2s.
  EMD Demo/Test units were always interesting,like the original
  SD24 that tested on DM&IR for over a year.
       Spikre
       
 

[wazzou]

Much larger "porch" on either end of the SD40-2.

Flexicoil trucks vs HTC trucks on the Dash 2.

Did the porch lengths differ?  I thought they both used the same 16 cylinder 645 on the same frame as the SD45 with the 20 cylinder, thus the shorter hoods and longer porches.

[Mark5]

Did the porch lengths differ?  I thought they both used the same 16 cylinder 645 on the same frame as the SD45 with the 20 cylinder, thus the shorter hoods and longer porches.

Short answer: yes.

The frame used on the SD40-2 and SD45-2 is some 3' longer than the non-dash2 models (as pointed out above).

Mark

[davefoxx]

Water sight glass on the engineer's side long hood for one.  Possibly some dustbin hatches or fans differ but I can't say for certain.

Much larger "porch" on either end of the SD40-2.

Flexicoil trucks vs HTC trucks on the Dash 2.

^This and that.  My understanding is that the change in the truck design from Flexicoil to HT-C trucks required a longer truck, because the traction motors all face the same direction on the HT-C.  This required a longer frame, so the SD40-2 frame is approximately three feet longer than the SD40.  This allowed room for a longer hood, and the SD40-2's hood is approximately 18" longer than the SD40s.  The longer hood with an even longer frame is what created the spotting characteristic of the front and rear "porches" on the SD40-2.

DFF

[Spikre]

 
   Flexi-Coil truck - 163" or 13'7" wheelbase.
   HT-C truck ----163.3/4" or 13'3/4" wheelbase,with the large rear Traction Motor Support.
   for comparision:
   GE FB-3 truck --163" or 13'7" wheelbase.
  Alco GSC Hi-Ad or Add -Hesion Truck-163" or 13' 7" wheel base
  originally the GE FB-3 was cast by GSC or ADK,later Buckeye then LFM continued the GSC
  design,but some say 90s FB-3s were cast by Atchison/Rockwell.
   EMD 1966 Test units:
   SD40X to GM&O 950,later ICG,then IC/CN.
   GP40X - to IC 3075, rebuilt to a GP35 eventually
   SD40X- 434B-434F to U.P.
     Spikre
       

[Spades]

Some SD40-2 had exhaust silencer.  Did the SD40 ever come with an exhaust silencer?

[C855B]

IIRC, I don't think so. The first EMD-issue silencers were on SDP40Fs, and by that point the Dash-2's were production. I specifically remember various members of my railfan clique cussing and discussing the "slush boxes" on the new Amtrak power, and why couldn't they just leave "glorious noise" alone.

[Spades]

I thought the exhaust silencer had something also to do with emission controls.

[C855B]

Nope. EPA wasn't even looking at non-road diesels until 1985. Silencers were noise abatement only.