EMD truck casting variations

In the latest locomotive drawings I've been working on, I've started looking up the variations in trucks depending not only on the time they were made, but also on the foundry. The most famous differences are probably the readily visible Adirondack vs. GSC/Rockwell/Atchison castings of GE 3-axle trucks, but I've found that other trucks show more numerous (but more subtle) variations.

I'm still early in my research, but so far I've compiled the variations I've observed in EMD Blomberg trucks, complete with drawings:

http://trainiax.net/metruck-gp.php

I hope eventually to cover all major locomotive truck types.

Thanks, Trainiac! That's the kind of often-overlooked attention to detail I look for on these forums.
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Being mainly a fan of GE locomotives… There has been some discussion, on the GE forum, of the modifications needed in order to use "Blomberg" trucks on GE locomotives with the larger GE traction motors. Have you spotted anything visible from outside?

I've looked up photos of Blomberg-equipped GE units over the years trying to find the differences, but the changes to accommodate GE traction motors are largely invisible from the outside (it would take a brightly exposed direct side view to see the changes). I'd estimate the traction motor cases extend about 2 inches farther from the axle centerlines on GE traction motors than on EMD ones, plus an additional inch or so for a slightly less compact motor suspension on the GE motors - these are estimates based on photos.

Another discussion here mentioned that only the inner transoms on the Blomberg truck frames required modification to fit the GE motors - and based on what I can see in the EMD truck diagrams, that would make sense. The bolster is nearly a foot away from the edges of the original motors and would still have lots of room left over with GE motors.

Visible differences on the GE-equipped Blombergs that I can see include the re-routed brake piping, running under (rather than over) the brake cylinders, presumably for clearance. When the clasp brakes were changed to single-shoe brakes, the brake beams were attached to the safety strap in a similar manner to modified EMD units. Most appear to have received new sand hose brackets welded onto the bottom tie bars, as well as new GE-style wheel bearings. The GE underframe would require motor air ducts that matched the truck's 9' wheelbase, which would be the same as the FB-2 truck but different from the Type B truck.

I'm not sure if it counts as an EMD truck, but I've read that MPI uses a lengthened version of the Blomberg truck under their MP series power. It might be interesting to incorporate those too, if there's truth to that.

Michael Eby--
Thanks for your careful response to aGE-lover's query! (If you don't object, I'll copy it-- maybe later in the week-- to the string on theGE forum where these trucks were discussed.)
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Re: "The GE underframe would require motor air ducts that matched the truck's 9' wheelbase, which would be the same as the FB-2 truck but different from the Type B truck." I suspect that there is a certain flexibility in the motor air ducts, so that this wouldn't be a problem. Evidence: despite the different wheelbases of the FB-2 and "Type B" trucks, GE units are sometimes re-equipped from one type to the other, even by people who OUGHT to understand what a GE locomotive needs to keep it happy. Some number of Santa Fe (ex-Santa Fe? I don't remember exactly when this happened) B23-7, originally delivered with "Type B" trucks, were re-equipped with FB-2 by… GE, when GE got a contract to manage maintenance of Santa Fe's GE locomotives!

(F.w.i.w…. The string on the GE forum in which "Blomberg" trucks are discussed is titled "Odd Truck Trivia Questions":
http://railroad.net/forums/viewtopic.php?f=8&t=141609" onclick="window.open(this.href);return false;
)

The MPI Blomberg truck has a 9" longer wheelbase in order to fit 'GE style' motors.

The MPI swinghanger truck has a wheelbase of 112" or 9'-4", lengthened from the EMD design to accommodate the larger GE motor with only minor alteration, although none have been built with GE motors.

If we are talking about just EMD truck castings, I have noticed slight differences between LFM, and Dofasco castings.

@Engineer Spike - Indeed, the LFM and Dofasco castings are different - I made drawings of them in the original link. EMD revised the castings further when LFM was replaced by Rockwell (later Atchison) but some 2nd- and 3rd-generation units came with remanufactured LFM castings (such as M-type Blombergs that were originally standard Blombergs).

The progression of foundries over time is easier to see in EMD 6-wheel trucks. For instance, there is no such thing as an LFM HT-C truck, but most early Flexicoil trucks (SD35 and earlier) were cast by LFM.

trainiac wrote:@Engineer Spike - Indeed, the LFM and Dofasco castings are different - I made drawings of them in the original link. EMD revised the castings further when LFM was replaced by Rockwell (later Atchison) but some 2nd- and 3rd-generation units came with remanufactured LFM castings (such as M-type Blombergs that were originally standard Blombergs).

The progression of foundries over time is easier to see in EMD 6-wheel trucks. For instance, there is no such thing as an LFM HT-C truck, but most early Flexicoil trucks (SD35 and earlier) were cast by LFM.

LFM>Rockwell>Atchison Castings>Bradken is really just one operation with different owners or parent companies but the facilities and people were/are the same operating continuously in Atchison, KS. The 4-wheel swing hanger truck evolved over a very long period of time with continuous improvement (mostly cost reduction) over that time. The changes in the spring pocket beads you observed were made to deal with the higher axle loads in later years. There are no HT-C's cast by LFM simply because it was already Rockwell at the time the HT-C was developed.

The Dofasco swing hanger truck differs slightly from the LFM as it was developed and tooled by Dofasco without using EMD drawings. Diesel Division, prior to the consolidation with EMD around 1987, simply purchased them from Dofasco, but the design was never officially approved by EMD's LaGrange Truck Design Group as I recall.

Dave

LFM>Rockwell>Atchison Castings>Bradken is really just one operation with different owners or parent companies but the facilities and people were/are the same operating continuously in Atchison, KS. The 4-wheel swing hanger truck evolved over a very long period of time with continuous improvement (mostly cost reduction) over that time. The changes in the spring pocket beads you observed were made to deal with the higher axle loads in later years. There are no HT-C's cast by LFM simply because it was already Rockwell at the time the HT-C was developed.

The Dofasco swing hanger truck differs slightly from the LFM as it was developed and tooled by Dofasco without using EMD drawings. Diesel Division, prior to the consolidation with EMD around 1987, simply purchased them from Dofasco, but the design was never officially approved by EMD's LaGrange Truck Design Group as I recall.

I was aware of the LFM > Rockwell > Atchison progression after discovering the Blomberg frame casting variations - hence the absence of LFM HT-C trucks. Interesting about the Dofasco castings - that would explain why they don't match any EMD drawings I'd found, and why the general design varied very little over the years.

On on of D&He's ex LV GP38-2s, I noticed General Steel Castings markings. Who knows where this came from. Point is, I have never seen any other GSC cast Blombergs.