• Erie-built truck design

  • Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.
Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.

Moderator: pablo

  by Allen Hazen
That weird-looking fabricated truck used on some FM-GE "Erie-built" units: maybe it's not so weird after all. I think it is, in its mechanical principles, very similar to the (Martin Blomberg designed) A1Atruck used on EMD's E-series passenger locomotives.
Looking at photos, the Erie-built truck shows swing hangers with elliptical springs in the same positions as the E-unit truck: I'm guessing that subsystem is similar in design principle. (The functional equivalent in the drop-equalizer trucks used in other Erie-builts-- and Alco passenger units-- is hidden from view.) This subsystem is concerned with "secondary" suspension: suspension of the bolsers and carbody from the truck frames.
The "primary" suspension system-- how the truck frame is suspended on the axles-- is what looks unfamiliar. On the drop equalizer trucks, the equalizing levers are the drop equalizers, the prominently visible bars that dip down below axle level between the axles. On the EMD truck (this from the description of the trucks in Jim Boyd's "Passenger Alcos" book) are ABOVE the axles, and hidden from view within the frame casting. I think what we see in the fabricated Erie-built truck is probably functionally equivalent to this, with the difference that the equalizing levers (the bars with the straight bottoms and curved tops that connect the axle-boxes) are displayed on the outside face of the truck frame: an arrangement which may have seemed more natural with a truck fabricated from flat plates than it would have with EMD's cast truck frame.
At least some of the Victorian Railways B-class EMDs ("AA-7": double ended F-unit carbody on SD running gear, among the first EMD six-motor units and one of the early Australian mainline diesels) were delivered with fabricated (welded) truck frames-- it was anticipated at the time, and in fact happened, that these would be prone to cracking after a few years (they were replaced with cast frames when the locomotives were several years old). Did GE anticipate any comparable problem with its fabricated truck frames? And did any of the Erie-built units last long enough for problems to appear?

  by Typewriters
Interesting speculation; you know that I've followed the F-M history farily closely, reading anything concerning it. I've never seen reference to the kind of problems you mention with these trucks, but then again, most of the time these units were quickly removed from service in which they'd experience high speeds (in the examples built for passenger service) and so one wonders, theoretically, that if this potential flaw did exist, it were mitigated or masked by the reduction in speed of operation. I would hasten to add, though, that I'd bet that the (rather heavy) weight of the units was considered well in the design when developed.

How's that for a post saying essentially nothing -- except "never read of it happening!" With all the press freely given to the maladies of the Erie-built units, you'd have to think that if this one existed it would have been all over the place by now.

-Will Davis

  by Allen Hazen
Of course, GE had ***LOTS*** of experience with welded truck designs by then-- they'd been using them at least since the IR-engined switchers for the Bush Terminal, and a lot of the lighter GE locomotives (44 ton, 70ton, industrial) seem to have had fabricated trucks.
And maybe you can do better designing a fabricated truck from the outset than you do if you try to "simulate" a cast frame with weldments. My copy of the book about VicRail's B-class is in my office in Melbourne, where I'll be able to consult it in about a month. When I can, I'll see if there are interesting further details and will post them if there are. (I ***think*** I remember that the welded trucks were used in an effort to maximize Australian content in the locomotives-- US dollars were in short supply in Australia at the time-- at a time when Commonwealth Engineering, the EMD licensee who assembled them, didn't have adequate foundry capacity: they were intended to be temporary, and so were designed to be interchangeable with the EMD-standard cast design.)

  by mxdata
Allen, going back to this older string, I just wanted to offer one piece of information that was provided many years ago by a manager who worked at EMD during World War Two. He commented to me that some design decisions in the mid-to-late war years were heavily influenced by the availability of resources on hand locally and the problems of transporting larger components. Companies that already were using welding extensively tended to find ways to adapt that technology rather than wait in line for foundry parts produced by others.

  by Allen Hazen
The possibility of revisiting older strings when one has new information is one of the nice things about these forums! (Very few of the historical and technical questions we discuss get answered so definitively that there is no room for further contributions!)

What you suggest may well be part of the story. (Mind you, for the Erie-builts the truck castings would not have had to be shipped interstate: "Railway Mechanical Engineer" for May 1948 (*) in an article on the PRR's freight Eries, says the trucks came from GSC at Eddystone, PA.) A hazy recollection of something I once read -- probably one of the "Trains" articles I have cited on other strings, or maybe Kirkland's Lima/FM book -- is that there was supposedly a cost advantage: either absolutely or by scaring GSC into a competitive quote.

In any event, the very first Eries (the first three for UP) had the welded truck, the next ones delivered (ten months later-- I think there was a strike, but don't remember whether it was at Beloit or Erie) had the cast-frame drop-equalizer trucks, and a few later ones had the welded truck -- use of the welded truck seems to have been discontinued before the end of Erie production. (According to the Erie-built roster in the article in "Railroad Model Craftsman" for October 1975 (**), the last Eries with the welded truck were NYC 5000-5001 in October 1947, with the cast truck used on the remainder -- the majority of Eries built -- up to the last, NYC 4400-4405 in March/April 1949.)
(*) Reproduced in "The Train Shed Cyclopedia #64".
(**) Which has HO drawings of FIVE phases of Erie-built: Phases II/III and IV/V, however, being "phase-doublets" differing only in the truck used.

  by Allen Hazen
The same "Train Shed Cyclopedia" volume reproduces the article on UP's first ABA set of Erie-builts, from "Railway Mechanical Engineer" for November 1946. Three paragraphs describe the trucks:

"The two six-wheel pedestal trucks on each unit were built by the General Electric Company. The structural parts are fabricated into an integral unit by the welding of accurately cut shapes and plates. The truck parts consist essentially of two side frames, a cross tie at each end, two pedestal units and a swing bolster. The side frames have journal box openings and spring suspension.

"The swing bolster is an integral fabricated structure carried by four semi-elliptic springs at each of four corners. It is designed for 2 1/4-in. free lateral motion. The lateral shock on the trucks is cushioned by maens [sic] of a spring-loaded arrangement in the truck pedestal jaws. The complete truck is designed to provide increased strength with decreased weight at reduced cost.

"The rolled steel ["wheels" obviously omitted in original--AH] are 40 in. in diameter with rims 2 1/2 in. thick, heat treated, and turned to A.A.R. standard contour. Clasp brakes on each wheel are actuated by a separate air cylinder. Wheel and axle assemblies are removable with the motor."


The general idea of a welded-frame truck with FLAT frame sides and the equalizers (cut (?I assume?) from flat plates) mounted flush against the outside of the truck frame seems to have been something of a standard GE design approach. While looking for Erie-built information just now I happened on the February 1981 issue of "Railroad Model Craftsman," with an article on the Ford Motor Company / Wellsville, Addison and Galeton center-cabs: their trucks also seem to have been of this type.