GE powered MLW in Tanzania

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GE powered MLW in Tanzania

Postby renrut44 » Thu Nov 17, 2016 7:06 am

SMH Rail from Malaysia have rebuilt fifteen 1971 vintage MLW metre gauge MX620EA at the Morogoro Workshops in Tanzania

Locos are renumbered 88U01 - 88U15

The engine used in the rebuild appears to be a 7FDL-8, retain the 1C-C1 bogie arrangement

https://www.facebook.com/photo.php?fbid ... =3&theater

https://www.facebook.com/photo.php?fbid ... =3&theater

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Re: GE powered MLW in Tanzania

Postby MEC407 » Fri Nov 18, 2016 1:45 pm

They look great! The GE V8 will serve them well for decades to come.
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Re: GE powered MLW in Tanzania

Postby Allen Hazen » Fri Nov 18, 2016 2:12 pm

Thanks for posting these! One of the in-shop photos gives a reasonably clear view of the generator: people who know their generators better than I do, what is it? Is it the original generator from the locomotive's previous life? (One of the advantages of using the GE FDL to reposer an Alco, I'd think, is that it is similar enough to an Alco 251 in such things as speed that it should be compatible with the original electricals.)
---
This is at least the second time GE FDL engines have been used in repowering Alcos. A while (about a decade?) back, a number of Australian locomotives, originally built with 12-251 engines, were rebuilt using the innards of ex-Conrail C30-7A units, including the FDL-12 engines. (In that project, I think the generators from the C30-7A were used: the rebuilding took what had been a 2,000 hp locomotive and produced a 3,000 hp unit.)
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Re: GE powered MLW in Tanzania

Postby renrut44 » Fri Nov 18, 2016 4:19 pm

While on the subject of SMH Rail and Africa, the company is also active in Zambia, with a team based at Kabwe (Broken Hill)

Have not discovered what core was used, suspect U20C as ZR have a number of these hulks stored at Kabwe

https://www.facebook.com/photo.php?fbid ... =3&theater

https://www.facebook.com/photo.php?fbid ... =3&theater

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Trials on mainline at rear of Kabwe Works
https://www.facebook.com/chuma.changa/v ... =3&theater

Appear to be similarities in long hood with Tanzanian rebuilds
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Re: GE powered MLW in Tanzania

Postby Pneudyne » Fri Nov 18, 2016 4:32 pm

The generator/alternator certainly looks like a GE unit (and maybe more like an alternator than a generator, but I’m not sure), with the characteristic triplex auxiliary drive gear set. (That arrangement was also used by AEI and Heavy Electrical Bhopal.)

The first batch (of 20) of those Tanzanian 88 class MLW MX620 locomotives (ordered when it was still EAR) had CGE GT586 main generators. The second batch (of 15) might have had alternators, but right now I cannot find definitive information. As a cross-check, the second batch of the Malawi Shire class MX615, built just after the second Tanzania batch, had alternators whereas the first batch, built just after the EAR group, had generators. So alternators may have been standard for the MX-series by the later 1970s.

So I doubt that fitting a GE FDL engine in place of an Alco 251 and retaining the original generator/alternator would have been too difficult. For example, an early version of the GT586, the GT586A2, was stated by GE to fit either the Alco or Cooper-Bessemer engine. That the rebuild programme involved 15 locomotives suggests that it might have been the second class 88 batch that was rebuilt.

I imagine that the power output as rebuilt was about the same as the original, namely 2150/2000 hp. Given that the 1-C-C-1 wheel arrangement was retained, I’d infer that moderate axle loading is still a requirement. The originals had an axle loading of roundly 29 000 lb, so much more than 2000 hp might make them too light-footed.

Replacing the original 12-cylinder engine with an 8-cylinder engine was logical given the progress in per-cylinder outputs since the originals were built. The GE FDL-8 had reached 2000 hp by the early 1990s, as evidenced by the U20C 8-cylinder export model (not to be confused with the much better-known 12-cylinder U20C, which was one of the stalwarts of the 1960s and 1970s when it came to dieselization in the CMT gauge world.)

One could ask why not use an Alco 8-251, given that the basic engineering for its installation had been done by MLW for the MX615, which used the same frame as the MX620. But the 8-251 was quite rare – in locomotive service anyway - although Africa (Nigeria and Malawi) may have been the biggest market. On the other hand, the FDL-8 was very widely used, particularly in Africa. I suspect that the FDL was anyway the better of the two engines, and that the difference may have been more marked in the 8-cylinder case. Apparently 45-degree vee-8 engines are not easy to get right from a balance and vibration viewpoint.

This Tanzanian rebuilt fleet is a remnant of what was once a worldwide fleet of 732 diesel-electric locomotives with the 1-C-C-1 wheel arrangement, built over the period 1950 through 1978. Collectively they make an interesting study of contrasting designs and reasons therefor, and cover the gamut of running gear designs from worse-than-awful to excellent.


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Re: GE powered MLW in Tanzania

Postby Allen Hazen » Sat Nov 19, 2016 8:14 pm

Alternator. Yes, I think this might be what it is. Both of the relevant GE direct-current generator type (GT581.GT586) have a coned section. (Starting from the engine, the generator has a cylindrical body, followed by a coned section reducing the diameter to perhaps 2/3 that of the cylinder, then the mountings of the auxiliaries.) This doesn't: it looks more like GE traction alternators in this regard: they are more cylindrical for the full length. … MLW used an unusual traction alternator on the M420W roadswitcher, a model not used on any U.S. GE or Alco locomotive: the GTA-17. This was apparently a shortened (so: lightened) variant of the GT-11: since the GTA-11 was used on units o up to 3600 hp, it was obvious more than needed on a 2,000 hp unit, though GE seems to have been happy to use it on alternator-equipped U23B. It seems plausible to me that MLW would have used this, lighter and doubtless cheaper, alternator on an export locomotive rated 2000 hp: particularly one designed for use on dodgy track where shaving ounces was a priority. … (Pure speculation, but perhaps Canadian GE developed the GTA-17 at MLW's request for export locomotives.)

As for the choice of the FDL-8 over the 8-251… I'm not sure the eight-cylinder 251 was ever developed for 2000 hp. It seems to have been a problematic engine in locomotive service even at 1500 hp: serious vibration problems despite heroic countermeasures (I think it had an auxiliary shaft parallel to the crankshaft carrying extra balance weights). The FDL-8 does not seem to have had these problems, or not to the same extent: perhaps the unusual "master and servant" arrangement of connecting rods on the FDL made it, as far as balance and vibration are concerned, more like an inline 4 than a conventional V-8. And I think the cast frame of the FDL may be better more robust than the 251's welded frame at high outputs.

---

Your "world-wide fleet of 732 diesel electric locomotives with the 1-C-C-1 wheel arrangement" … would include the British Rail Classes 40,44,45 and 46 (and the Southern Region BR prototypes)? Which did you have in mind as exemplifying worse-than-awful running gear design, pray tell? …
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Re: GE powered MLW in Tanzania

Postby MEC407 » Sat Nov 19, 2016 9:29 pm

Speaking of 251s... I checked Fairbanks Morse's web site to see if they offer a 251 in either a V8 or I8 configuration, and they do not. They also no longer offer the V18 version, which was still listed on their site as of three or four years ago.
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Re: GE powered MLW in Tanzania

Postby Pneudyne » Sun Nov 20, 2016 12:19 am

Allen Hazen wrote:MLW used an unusual traction alternator on the M420W roadswitcher, a model not used on any U.S. GE or Alco locomotive: the GTA-17. This was apparently a shortened (so: lightened) variant of the GT-11: since the GTA-11 was used on units o up to 3600 hp, it was obvious more than needed on a 2,000 hp unit, though GE seems to have been happy to use it on alternator-equipped U23B. It seems plausible to me that MLW would have used this, lighter and doubtless cheaper, alternator on an export locomotive rated 2000 hp: particularly one designed for use on dodgy track where shaving ounces was a priority. … (Pure speculation, but perhaps Canadian GE developed the GTA-17 at MLW's request for export locomotives.)


The Malawi MLW MX615 fleet (C-C running gear) with the Alco 8-251 engine, had CGE GT581 generators (first batch) and GTA19 alternators (second batch). The GTA19 was a lightweight version of the GTA17, with reduced power input capacity. Still, it could probably handle 2000 hp, so may well have been used on the second batch of the Tanzanian MX620s. But if not that, as you say, then the GTA17 was the most likely alternative. The Nigerian MX615 fleet (one batch circa 1972-73, with 1-C-C-1 running gear) all had CGE GT581 generators.

Allen Hazen wrote:It seems to have been a problematic engine in locomotive service even at 1500 hp: serious vibration problems despite heroic countermeasures (I think it had an auxiliary shaft parallel to the crankshaft carrying extra balance weights). The FDL-8 does not seem to have had these problems, or not to the same extent: perhaps the unusual "master and servant" arrangement of connecting rods on the FDL made it, as far as balance and vibration are concerned, more like an inline 4 than a conventional V-8. And I think the cast frame of the FDL may be better more robust than the 251's welded frame at high outputs.


The use of balance shafts (Lanchester balancers) was not unusual on 45-degree vee-8 engines. For example English Electric used them (three, I think) on the vee-8 version of its RK engine, and also on the four-line version (two in that case). I don’t know whether GE used them on the 7FDL-8, but I should not be surprised. But evidently the devil is in the detail.

Allen Hazen wrote:Your "world-wide fleet of 732 diesel electric locomotives with the 1-C-C-1 wheel arrangement" … would include the British Rail Classes 40,44,45 and 46 (and the Southern Region BR prototypes)? Which did you have in mind as exemplifying worse-than-awful running gear design, pray tell? …


The answers are (1) yes; and (2) exactly those.


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Re: GE powered MLW in Tanzania

Postby renrut44 » Sun Nov 20, 2016 6:01 pm

MEC407 wrote:Speaking of 251s... I checked Fairbanks Morse's web site to see if they offer a 251 in either a V8 or I8 configuration, and they do not. They also no longer offer the V18 version, which was still listed on their site as of three or four years ago.


I suspect that Fairbanks Morse's 251 engine line up mirrors that of DLW, and that FM may be sourcing from India

It would appear that Alco engine manufacture has been transferred from DLW at Varanasi to the Central Workshop, Golden Rock, situated in Ponmalai (Golden Rock), Tiruchirapalli in the Indian State of Tamil Nadu. DLW required the space occupied by Alco build to expand their 16-710 production line. Indian Railways "block reclimation" is centralised at Golden Rock, with space and skilled labour available
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Re: GE powered MLW in Tanzania

Postby Typewriters » Mon Nov 21, 2016 1:19 pm

In answer to a question, the GE 7FDL-8 series engines had two balance shafts in the crankcase from the very beginning.

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Re: GE powered MLW in Tanzania

Postby Pneudyne » Mon Nov 21, 2016 3:06 pm

Thanks for that, Will. It does not at all surprise me.

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