• UD18B curiosity question

  • 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: MEC407, AMTK84

  by Allen Hazen
GE's "U-series" diesel locomotives before the U25B were export locomotives, but the UD18B of 1956 was a standard gauge unit of North American dimensions: in principle, I would think it COULD have been a competitor for the GP-9 and RS-11 in the U.S. domestic market. Greg McDonnell's "The U-Boats," however, reports that the first pair built, after testing (with GE reporting marks) on the Erie were sent to Mexico to demonstrate; NdeM bought them and followed by buying the only production order (8 units late in the same year).

Does anyone know if GE ***tried*** to market this model domestically? (I think they may have been a few tons lighter than average GP-9 or RS-11, so perhaps some granger road with lightly-built branch lines and a catholic appetite for diesels from multiple builders -- I'm thinking of CRI&P and CMStP&P here -- might have been interested.)

If not, was there a good reason why not? (Something technical I don't know about, maybe, or maybe when GE and Alco cancelled the Alco-GE sales consortium they signed some sort of non-competition agreement?)
  by Pneudyne
There is evidence (attached) that the UD18B was designed with the American market in mind. But on the other hand I have not seen any evidence that GE actively promoted its sale in the USA. Possibly one might glean something from the pages of “Railway Age” for 1956 and thereabouts, but I don’t have access to the back copies of this journal.

One may wonder whether the “D” in UD18B stood for “domestic” or “demonstrator”, or perhaps both.

Apart from a handful of dedicated heavy-haul operations, usually mineral, few overseas railroads would have been able to accommodate locomotives with the profile dimensions and axle loading of the UD18B. Maybe an A1A-A1A or C-C version would have had some potential applications, but not many. One thinks of the Alco DL540, which was of an “in-between” size, and which had only one sale, albeit a sizeable one (130 off) to Argentina. Alco’s rethink on this resulted in the DL541 (and succeeding DL543), but this, like the EMD G16, was still a bit larger and heavier than most CMT-gauge roads wanted; both Alco and EMD had but one CM gauge customer each, as I recall. On the other hand, GE, having designed specifically for the sub-standard gauge market, “got it right” with its export U18C and succeeding U20C, the latter becoming something of a CMT-gauge standard in the 2000 hp class, and one that was imitated first by EMD with its GL26C (inferentially built as a ringer for the U20C in order to capture a share of the South African market) and then by MLW with its MX620, designed with the African market in mind.

In hindsight, it looks as if GE was not too serious about selling the UD18B into the US domestic market, although it probably would have built it had anyone wanted; it did build a small fleet for Mexico. Perhaps it can be seen as something of an “amuse-bouche” ahead of the U25B to follow.

Incidentally, something I hadn’t noticed previously is that the unlike the other road locomotives in the initial Universal series, the UD18B did not have floating bolster trucks, but rather the conventional swing bolster types with elliptical secondary springs.

DRT 195611 p.433.jpg
DRT 195611 p.434.jpg
DRT 195611 p.435.jpg
  by Pneudyne
Re the Mexican UD18B fleet:
DRT 195703 p.39.jpg
  by NorthWest
I think GE wanted to enter the North American market with a strong product. I tend to view these units as test beds for later U25B, though they lacked certain features of the later locomotives. Along with the two prototype U25Bs, these seem to be somewhat of dress rehearsals for later units, which would explain the lack of marketing. The "D" was probably to distinguish the locomotives from the concurrently catalogued (but ultimately unbuilt) U18B. (I've got more to say on other topics, but I am currently out of time.)
  by chrisf
Pneudyne wrote:Incidentally, something I hadn’t noticed previously is that the unlike the other road locomotives in the initial Universal series, the UD18B did not have floating bolster trucks, but rather the conventional swing bolster types with elliptical secondary springs.
The 2-axle GE Floating Bolster truck didn't appear until about 1973, so it wouldn't have been an option for the UD18B, nor most 4 axle U-series engines. It's unlikely that the traction issues that happened with the standard "AAR Type B" truck in higher power applications would have been an issue with the UD18, and the FB-2 probably wouldn't have been worth the expense even if it existed at that point.
  by Pneudyne
Although on the other hand, the export U9B and U12B models (first deliveries in 1957) were fitted with floating bolster B trucks from the start, in gauges from three-feet to 5'6". The never-built export U18B would also have had these trucks. So a heavier, longer wheelbase version for the UD18B might have been not-too-much of an engineering effort had GE wanted to do it. That it did not tends to confirm that it had not envisaged series production of the UD18B. And as you say, this model was less in need of improved adhesion than the lighter export models.

  by Allen Hazen
Greg McDonnell's book "The U-Boats" has a bit of chronology on the UD-18B. The first two, demonstrator, units were built in June 1956. (For comparison: Alco's first RS-11/Dl-701 units, with the 1800 hp 12-251 engine, were built in February 1956.)
After testing on the Erie Railroad (GE was apparently on good terms with the Erie's management, since the 1954 four-unit test set(*) was operated on the Erie for several years) they went to Mexico. The eight follow-on units for NdeM were built in November 1956.
So. We don't know if GE tried to interest U.S. railroads in the type, but it sounds as if the demonstrators never demonstrated on any U.S. line.
  by Allen Hazen
Reading the text of the ad Pneudyne has posted…
(i) GE calls them 1980 hp units. This is a brake horsepower rating (commonly used outside of North America, so the obvious rating to use in an ad in a British-published journal with international readership): it corresponds to 1800 hp input to traction generator, the rating usually used for diesel locomotives in North America.
(ii) It is claimed that they have "greater tractive effort and higher horsepower than other locomotives of the same general type." Which seems a bit strange, given that Alco's Dl-701, with the same trucks, essentially the same GE electrical gear, a bit more weight on the drivers (I think), and a -- nominally -- 1800 hp engine was also on the market!
(iii) According to Steve Palmano's historical sketch of GE's export U-series (link in the first post of the "GE Export Diesels" string on this forum), GE's originally claimed 1980/1800 hp for the 12-cylinder C-B engine was based on fairly severe altitude and ambient temperature assumptions: when GE "rebranded" the export locomotive powered by it the "U20C," this reflected a change to the conditions standardly used in international railway circles, and not on an actual change in the engine!
So (since I don't know what assumptions Alco used for its engine ratings): is it possible that an "1800 hp" GE locomotive in 1956 was (not equivalent to but) more powerful than a contemporary "1800 hp" Alco locomotive?
(iv) When the four-unit test locomotive was sold to Union Pacific, it was labelled a "UM20B", and it is said that it had 2000 hp engines. But were these engines actually more powerful than the supposedly 1800 hp engines that had been in two of the units since they were built in 1954? (Calling the locomotives UM20B might have been useful for GE sales-wise: imagine a GE representative taking a high official of some third-world railway to lunch and trying to persuade him to sign for a batch of U20C. Official: But if your U20 is so good, why aren't the railways in your own country signing up for it? GE man: Well, the Union Pacific has actually bought four of them.)
And… Even though GE quotes 1980 hp in the ad, they had used 1800 as the basis for the model number.
  by Allen Hazen
(And… for a very nice COLOR photo of the GE 4-unit test locomotive operating in Erie Railroad colours--
look at the masthead of the Davis brothers' blog:
http://railroadlocomotives.blogspot.ca" onclick="window.open(this.href);return false;

…and if you scroll through their past postings, you will find a number of very informative articles on points of GE locomotive history, all based on original GE documents.)
  by Pneudyne
The GE engine rating step change is I think explained here:
DRT 196210 p.407.jpg
So the UIC gross rating for the 12-cylinder engine as used in the UD18B was in fact 2150 hp.

Regarding Alco, I have a specification for the DL-535S that quotes the power output as 1350 hp UIC gross, 1200 hp for traction. 1350/1200 hp was in fact the standard number set associated with the DL-535 series, including the well-known DL-535E for WP&Y. From this one might reasonably infer that Alco typically quoted its gross ratings according to UIC. The DL-535 was introduced late in 1961 to infill a gap in the Alco export product range and give it a locomotive that would be proximate to the GE U13C and the EMD GR12, although it had the potential advantage of being lighter than both. Alco had to uprate its 6-cylinder engine considerably to do the job, as at the time it did not have an 8-cylinder version of the 251. Of Alco’s 12-cylinder export models, the DL-500 (2nd iteration), DL-540 and DL-541 were 1950/1800 hp, and the DL-543, introduced late 1961, was 2150/2000 hp.

  by Allen Hazen
Thanks for posting that interesting "Letter to the Editor"!

I know that Steve Palmano often referred to "Diesel Railway Traction," so his claim (in the historical essay I linked to in the other string) was very likely made in the light of this (as well as other sources) statement.

It does seem likely that Alco's horsepower ratings were made under UIC conventions: except for the Dl-535, their advertised ratings for late-1950s export models seem to have been in line with the ratings they used for domestic locomotives. So: an 1800 hp UD-18B very likely WAS more powerful than an 1800 hp Dl-701!
  by Pneudyne
A corollary question is when did GE change the way in which it presented its locomotive engine power outputs?

Its brochure “Built-In Power” dated 1961 August refers to the “new” system, inclusive of the UIC gross rating, and also the amended model designations, as follows:

U10B/C: 1090/1000 hp
U13B/C: 1420/1300 hp
U20B/C: 2150/2000 hp
U26C: 2750/2600 hp

In this case U26C referred to a never-built heavy export model (108 tonnes) that basically packed the 16-cylinder engine into the U20C frame. Judging by the tractive effort numbers quoted, it used the GE752 not the GE761 traction motors, and so like the U20B (also never-built) was available for SB gauges only, not CMT. This would have been GE’s contender in a fairly limited market for which Alco offered the DL560 and EMD the GT16 at about the same time. The U26C designation was recycled at the end of the 1960s for the uprated and stretched 12-cylinder model. Also, the U10B/C (6-cylinder successors to the U9B/C) were never built, and the U10B designation was recycled for the uprated end-cab model that initially was known as the UM10B (which designation was subsequently otherwise used.) In part Alco captured much of the six-cylinder market at the end of the 1950s with its DL-531, which being a bit simpler was probably sold at a lower price than the U9/U10, and in part the 900-1000 hp market moved away from road-switchers to end-cab units, as evidenced by the fact that EMD sold few of its G8 road-switcher after the GL8 end-cab model was introduced. Alco kept its 6-cylinder business alive by moving it up into the 1300-1400 hp slot.

Anyway, the change had been made by 1961 August, and probably a few months before that.

But the UM20B rebuilt prototype predates that by about a year. So this would probably represent the first use of a model number that reflects the “new” power rating system.

The GE brochure “Power for Progress” dated 1960 September still used the older designations and gross power numbers for the export Universals, namely U9, U12 and U18. But it does mention the U25B, which would appear to have conformed to the new system. In a 1963 January advertisement in “Diesel Railway Traction”, the U25B is described as being a 2750 hp locomotive, and that was the UIC rating for the 16-cylinder engine at that time.

On the other hand, the “XP-24” designation was logically based upon the older system. 2400 hp net for the 16-cylinder engine corresponded to 1200 hp net for the 8-cylinder engine.

So, phasing-in of the new rating system and the corollary changes in locomotive designations looks to have been a progressive process rather than a one-off event.

In the Alco case, the 2150/2000 hp DL-543 replaced the otherwise similar 1950/1800 hp DL-541 at the end of 1961, and that corresponded with an engine change, to the 12-251C from the 12-251B, in which inter alia the rated speed moved to 1025 rev/min to 1000 rev/min. So that looked as if it were a real change in engine output and not just a change of rating method.

EMD also used UIC gross ratings. That comes out in its fairly well-known rather expansive advertisement in DRT for 1958 November. For example, the G16 was quoted at 1950/1800 hp, with 1950 hp being the UIC rating.

  by Allen Hazen
McDonnell's book says the test set was "leased to the Erie" until mid-1959,and sold to the U.P. in late October 1959.
Given GE's somewhat cavalier attitude to model designations, I wouldn't (unless someone has contemporary GE documentation) bet a whole lot of money on their having been designated "UM20" when they were sold to U.P.: it's conceivable that this was a retrospective designation, assigned when GE started to advertise its U20C model.
The original, unbuilt, U26C is a fascinating might-have-been. (I wonder if GE tried to interest British Rail in a "UM26C": it might have stacked up nicely agains the Class 47 and Class 50!) … I have the sense that some "narrow gauge" railways are now looking for locomotives in the power class of current mainline North American ones: I think the locomotives GE is currently building for South Africa are over 4000 hp (so: either FDL-16 or GEVO-12). Since four 752 motors could absorb the power of a U25B, I suspect that six 761 motors might have been able to cope as well(*), so even if GE at the time didn't offer it, a Cape Gauge "U26C" wouldn't have been totally unthinkable.
(*) By the 1970s, obviously, since these are the motors on the later, 12-cylinder, U26C that was actually built. But this might have had an uprated version of the 761 motor: I don't know.
  by NorthWest
Wow, a lot of great information posted here. Thanks!
I think it may be important to note that some horsepower numbers are rounded considerably to fit a designation despite being over or under the advertised amount (differences due to fuel rack settings and parasitic load variations aside). IIRC, GE's B32-8s could more accurately be called B3159-8s.

This discussion on horsepower measurement variance is interesting and likely a reason that UIC primarily went to kW as a more accurate measurement.
  by Pneudyne
Allen Hazen wrote:Since four 752 motors could absorb the power of a U25B, I suspect that six 761 motors might have been able to cope as well(*), so even if GE at the time didn't offer it, a Cape Gauge "U26C" wouldn't have been totally unthinkable.
Yes, quite doable even back in 1961. Simply the U26C would have had the same CTE as the U20C, but with an MCS that was around 30% higher. The U20C with 60 mile/h gearing was 51 000 lbf at 11.5 mile/h. So the U26C would have been 51 000 lbf at around 15 mile/h. That was not too bad of an MCS for CM-gauge practice of the time; the EMD G12 with D19 motors and 62 mile/h gearing was in the same vicinity. GE probably would have built a CM-gauge (original) U26C had anyone wanted. I suspect that its advertised characteristics, based upon the 752 motor, were intended to stack up against the SB-gauge Alco DL560 and EMD GT16.

Some sense of 761 motor progress over time may be gleaned from the data available for the South African fleet, namely continuous current capability:

1958; U12B; 761A4; 590 amps
1959; U18C1; 761A3; 590 amps
1965; U20C; 761A6; 620 amps
1966; U20C1; 761A9; 615 amps
1971; U26C; 761A13; 655 amps

In terms of power input, an application at the high end of the 761 capability range would have been the E42C Cape-gauge AC electric built for Taiwan in the 1970s, which had a 3750 hp continuous rating. But in the manner of AC electric locomotives, this would normally have been accelerated on a more-or-less constant torque curve, not reaching the characteristic curve until well into the running speed range.
Allen Hazen wrote:The original, unbuilt, U26C is a fascinating might-have-been. (I wonder if GE tried to interest British Rail in a "UM26C": it might have stacked up nicely agains the Class 47 and Class 50!)
Nice idea, although assuming the full BR Class 50 list of special requirements applied, the devil would have been in the detail. I made a mental back-of-the envelope list of the some of the items involved, but I think that would be off-base for this thread.
GE Built-In Power 196108 p.14.jpg
GE’s adoption of UIC gross power ratings, based upon relatively mild ambient conditions, also meant that the deratings required for severe ambient conditions were more apparent.

By way of examples, the Colombia U20C was set at 2020/1870 hp, and the Zimbabwe U20C was set at 2090 hp gross. The latter had 761A5 motors, 610 amps continuous. The South African U20C fleet was fully rated at 2150/2000 hp, but the small U20C1 fleet retained the same 1980/1800 hp rating as the large U18C1 fleet. As these were all used in Namibia (much of which is “hot and high”), one assumes that some derating (vis-a-vis UIC) was required, but that the derating implied by GE’s original rating system was adequate.