• GE U50 and GTEL informations

  • Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.
Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.

Moderators: AMTK84, MEC407

  by lowflyer
Allen, bogieman
Thank you both for your kind inputs.
Yes, i can imagine how strong should be the connection to the locomotive, the impressive strong shears they need to support, of course regarding the moment to start to move the train because the couplers are mounted in front of the span bolster. I've realized from some pictures the points where the shears should be applied, the coupler first, then the pivot point of the first B+B truck (outter) and then the span bolster connection point to the locomotive.
Since this locomotive was used in cargo trains (heavy), i think they were condemned to fail due to the uge maintenance costs of the trucks (i can imagine the failure of the pin points???) I can't find also if the first and second generations of the GTEL used the same solution, B+B trucks with the span bolsters.

Be safe
  by bogieman
Allen Hazen wrote: Mon Nov 23, 2020 10:14 pm Bogieman--
Thank you! I was hoping you might comment on this.
(i) ... The GE and EMD eight axle units for Brazil (all the GE and the newer EMD ones having span bolsters and four B trucks) have the couplers mounted on the locomotive frame and not on the span bolster. Do they have the centre plate for the span bolster centered between the two B trucks?
(ii) I thought I had remembered reading something about GE motors being used on EMD DD types, but it would have been a LONG time ago, and I probably misremembered. Thanks for correcting me! (EMD did, of course, use GE motors on some units in the 1960s: the GP30 and GP35 units delivered on trucks, and with motors, from Alco trade-ins. Since they used the Alco trucks, the GE motors fit. On some discussion on this or another Railroad.net forum, there was some discussion of GE's use of EMD two-axle (Blomberg) trucks on some four-axle U-series units, and the issue of the dimensions of the motor came up: as I remember it, the "EMD trucks" on these U-boats had the frames of EMD trucks from trade-ins, but mated to a new and narrower bolster to accommodated the larger motor.
Thanks again!
On EMD's new GBB truck, which I designed, and the GE 4-axle span bolster truck, the center bearing between span bolster and underframe is centered between axles 2 and 3 to equalize static axle load.

Regarding use of GE motors in the EMD GP truck (we never called it Blomberg at EMD), I am aware of it being done by modifying the transoms in the motor nose area. The bolster sits between those inboard transoms so no change to it is required. The transoms are 5" in width so the mod consists of cutting out the center portion of the transom on the motor side to remove the existing nose lugs and welding in a casting with new lugs matching the GE motor that recesses the lugs 2" into the transom. I don't recall if any change is needed at the TM air duct location on the frame adjacent to the brake hanger brackets, even with an EMD motor it's close in that area.

  by bogieman
Allen Hazen wrote: Mon Nov 23, 2020 10:49 pm Trying (unsuccessfully) to get more details on the U50's trucks, I looked at
(part of a history of UP motive power). Locomotive types are covered, paragraph or so each, in roughly chronological order. In reference to the DD35, it says that 14 of them (DD35A 70-83) were built with GE traction motors from retired Alco FA locomotives. Either this is in error, or EMD kept no record of the truck modifications required.
Allen, you are absolutely correct that GE motors were used on some DD35's. While the EMD parts catalog only shows one truck frame part number, digging deeper, I found there are multiple traction motor air duct part numbers listed for the DD35, some of which go with GE motors. I haven't figured out how EMD would have accomplished that, any change to the truck frame should have resulted in a new frame part number; we were always very strict about creating new numbers if form, fit, or function changed for any part. I exchanged some emails with Don Strack who confirmed that EMD assigned a model designation of 752E20A for the reconditioned motors, perhaps there were some external motor changes to make the fit easier.

  by Allen Hazen
Thank you for your further information! Somehow (I don't remember who I got it from, let alone whether that person had obtained it legally) I have a copy of a GE document from 1971 (DF 70LC2160): a list of traction motor and generator types, apparently compiled to help the spare parts salespeople at GETS figure out what to send to a customer who wants to replace something obsolete. There are numerous "forms" (I think that is the word GE uses) of 752E traction motor, designated by adding additional numbers after the E. 752E20 is identified as a motor originally shipped as a 752A1 or 752C1, and later remanufactured to a later standard. GE doesn't seem (at that time) to have put further letters after the form number, so if EMD's records show 752E20A, the A may very well refer to some modification made by EMD in trying to fit them into the new trucks.
  by Pneudyne
Re the original request for information, including drawings, on the UP GE U50 and GTEL, the following books may be useful:

Giants of the West
A Pictorial Presentation of Union Pacific’s Super Powered Locomotives
George R. Cockle
Overland Publications, 1981
ISBN 0-916160-12-2

Plan Package Motive Power of the Union Pacific System
All Types 1869-1974
Kratville Publications, 1975

Turbines Westward
Thos. R. Lee
T. Lee Publications, 1975
ISBN 0-916244-01-6

Roaring U50’s….
Union Pacific’s Twin Diesels
Harold Keekley
George R. Cockle & Associates, 1978
ISBN 0-916160-06-8

  by Pneudyne
The span-bolster type four-truck wheel arrangement appears to have originated in the 1920s, where it was used for some interurban electric locomotives. Initially it was in articulated form, with the two span bolsters connected by an articulation joint that carried all buff and drag forces, the mainframe being total free of such.

The first “large” locomotive to have this B-B+B-B running gear was Illinois Central #9201, later #9202, of 1936, and built by the St. Louis Car Company subcontracting to EMC.

Kirkland (1) equated this type of B-B+B-B running gear with that of the NYC T class electrics, built from 1913. But the T class did not have span bolsters. Rather, the outer trucks acted as pilots to the inner pair of driving axles, which were rigidly attached to the main truck frame. One may think of it as having been a 2-B+B-2 type with powered pilot trucks, although in fact the T preceded the first of the latter wheel arrangement. Furthermore, the power pilot trucks of the T had no provision lateral for motion, and concomitantly, the inner axle pairs were mounted close together. Thus the whole assembly would have behaved somewhat like a 4-4-0 steam locomotive.

The GE GTEL4500 prototype appears to have been the first to use independent span bolsters, that is, not connected by an articulation joint. In part that may have been to improve the riding and tracking at higher speeds, and in part to allow space between the truck assemblies for underhung equipment. It also had lateral motion (swing-bolster) trucks, which were more suitable for higher speeds than the rigid-bolster types. That GE had a “horses-for-courses” approach is evidenced by the more-or-less contemporary VGN EL-2b class motor-generator electric, which had articulated span bolsters and rigid-bolster trucks, suited to heavy pulling at low and moderate speeds.

The mounting of the GTEL4500 couplers on the span bolsters might have been done to minimize throwover on tight bends. As noted upthread, this meant that all buff and drag forces went through the span bolster pivots. That requirement of truck pivots had been seen previously, for example on Illinois Central prototypes #9200 and #9202 (later #9201), of 1935-36. These had independent C trucks (i.e. they were C-C, not C+C) with the couplers mounted at the truck outer ends. Also, GE had used truck-mounted couplers on the 1939 steam turbine-electric prototype pair tested on the UP. These had the 2-C-C-2 wheel arrangement, with unconnected main trucks, so that the main truck pivots handled the buff and drag loads. This wheel arrangement was actually quite rare (estimated worldwide total 12), whereas the more familiar articulated version, 2-C+C-2, was much more common (estimated worldwide total 495).

N&W used the independent span-bolster running gear for its 1954 steam turbine-electric prototype #2300, in this case with C trucks. Here again, the couplers were mounted on the span bolster ends. Brown Boveri, Switzerland, proposed several GTELs in the late 1940s, one of which had used span bolsters with a mix of C and B trucks.

from Brown Boveri Review 194510,11 p.363.png

Given that UP repeated the GTEL4500 span-bolster running gear in the 1960s for the Alco C-855 and GE U50 types, I think it would be reasonable to infer that it had satisfactory riding and tracking characteristics at UP’s operating speeds.


(1) John F. Kirkland; Dawn of the Diesel Age; Interurbans Special 80; Interurban Press, 1983; ISBN 0-916374-52-1; see page 185.
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  by Pneudyne
The attached provides an outline dimensional comparison of the GTEL4500, GE U50 and Alco C-855A,B, all of which used essentially the same running gear.

Span Bolsters.jpg

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  by bogieman
Pneudyne, Thanks for posting these arrangement drawings, really helps to understand these locos.

  by Pneudyne
No problem – they’re interesting critters!

Also, here is a drawing for the VGN EL-2B, which had articulated span bolsters.


The front and rear span bolsters are somewhat different. The front bolster has a longer front overhang to carry the pilot and coupler. They have different truck centres, as well, 16’2” at the front and 16’10” at the rear. In both cases the .bolster centres are offset rearwards from the “equidistant-to-each-truck” points, 6.5 inches front and 2.5 inches rear. I imagine that this was done to get the weight balance right.

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  by Allen Hazen
Thank you... for several informative replies (here and on the BR Class 28 on the "General" forum)! Comments when I have fully digested.
W.R.T. to the dimensioned drawings of the GTEL, U50, and Alco C-855: one of the sources I consulted earlier suggested that, though GE re-used span bolster trucks from the GTEL on the U50, Alco used new ones. Dimensionally though (at least as regards inter-axle spacing and location of the span bolster to carbody centerpin), the trucks on the U50 and C-855 seem to be identical.
  by Allen Hazen
Of course, Alco would still have had to get new span-bolster trucks, even if the got them made to the same dimensions: there weren't enough trucks from trade-in GTEL to go around! UP had a total of 25 BBBB U50 (ten in the first lot, fifteen in the second, "Veranda," class), and something I read many years ago said that the trucks from the scrapped prototype (the double-cab unit, which bore the road number 50 when on UP) were re-used on one of them. But there were 26 U50: 23 for U.P. and three for S.P.
  by Pneudyne
Pictures of the complete span bolster assembly with trucks appear to be quite scarce. This is from the Strapac book on the SP GEs:

from Strapac SP GE p.40.jpg

That it is a picture of a prototype GTEL4500 set suggests that a similar picture for a GE U50 assembly couldn’t be found.

From that picture, it looks as if the span bolster pivot “pin” (more of a fat cylinder) was mounted on the locomotive frame and projected downwards into the span bolster. On the other hand, at least the Railway Gazette diagram for the Alco C-855 suggests that in that case, the pin was mounted on the span bolster and projected upwards into the locomotive frame.

RG 19640703 p.549.jpg

That might not preclude use of the same basic assembly. In the GE case, the hole in the span bolster would accommodate a liner, whereas in the Alco case, the same hole would be fitted (interference fit?) with the base of the pin.

As to which of the group, 23 UP U50, 3 SP U50 and 3 UP Alco C-855, got new span bolsters, I understand that this has been the subject of some debate. Lee, in “Turbines Westward”, noted: “Union Pacific records indicate that the three ALCO C-855 freight diesels, numbers 60, 60-B, and 61, used span bolsters from the turbines.”

Lee p.151.png

One may also infer from Lee’s notes that the disposition of the span bolsters from GTELs #51-84 was separate from that of the trucks, contrary to the case for #55-75.

If the Alco trio did not receive new span bolsters, then the SP U50 trio, and the initial three of the UP U50 fleet would be reasonable candidates for having had new span bolsters. Or the distribution could have been more random than that. But SP may have been less inclined to use a recycled UP item than UP itself. Also, I am not sure that it has been confirmed that all 26 GTEL4500 span bolster sets were re-used.

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  by Pneudyne
On the other hand, Cockle stated that the complete UP U50 order was built on trade-in GTEL4500 trucks:

Whether “trucks” meant just the trucks, or the trucks and span bolsters, is indeterminate.

Cockle p.144.jpg

But it does conflict with Lee’s claim that the trucks (in context just the trucks, not the span bolsters) from GTEL4500s #51-54 were traded in on a GE U25B order.

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  by Pneudyne
Pneudyne wrote: Mon Feb 01, 2021 4:09 pm
This is from the Strapac book on the SP GEs.
Details of that book, which has a chapter on the SP U50s, are as follows:

Southern Pacific Historic Diesels, Volume 5
General Electric U-Series Locomotives
Joseph A. Strapac
Shade Tree Books, 1998 December
ISBN 0-930742-19-2