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Posted by Miningman
on Saturday, December 01, 2018 9:00 PM
A good discussion on this ensued on the Quiz a while back
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Posted by Miningman on Sunday, July 23, 2017 10:10 PM
Allright then Gents and Penny.
What is this. Hint: Not a '57 Chevy

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Posted by RME on Sunday, July 23, 2017 10:46 PM
That's the second GMDH-1, the one that subsequently went to South America. Unless I am mistaken, these locomotives used the same class of prime mover that is in the RDCs, 6-110.
One of the four is now 5'6" gauge!
There's also a GMDH-3, which is 'half a loaf' for the critter crowd, with an 8V-71 -- interesting, because RDC repowers with Detroits were apparently generally considered underpowered failures:

I have no idea whatsoever why there was no GMDH-2. Someone here will know, so let's ask that next.
And what about this?

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Posted by Miningman on Sunday, July 23, 2017 11:19 PM
600 GMDH-1 A1713 9/1958 600 hp hydraulic unit testing/demonstrating on St.Marys Sub. in 1958. Bill Thomson
Eventually sold 5/1962 to Federal Railways of Brazil. No other 600 hp units were built aside from 1001.
H means Hydraulic! I don't know what a GMDH-2 is either. So good question!
As regarding your photo it looks like Baldwin built the front end !...nice cab too!
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Posted by RME on Sunday, July 23, 2017 11:51 PM
Miningman
As regarding your photo it looks like Baldwin built the front end !...nice cab too!
Hint: it is related to this:

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Posted by SD70M-2Dude on Monday, July 24, 2017 12:29 AM
RME
That's the second GMDH-1, the one that subsequently went to South America. Unless I am mistaken, these locomotives used the same class of prime mover that is in the RDCs, 6-110.
Another is still in regular use out my way, at the Kaybob gas plant near Fox Creek, AB (150 miles northwest of Edmonton). As the video notes it has been repowered, but I can't remember what engine type offhand. I do know the traveling mechanics who service it though, and will ask next time I see one of them.
https://www.youtube.com/watch?v=TMJcbwReQvw
And great to see the quiz has been restarted! Although I am not a frequent poster on the quiz threads I always read them, and have learned a lot from the expert-level questions.
Greetings from Alberta
-an Articulate Malcontent
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Posted by SD70M-2Dude on Monday, July 24, 2017 12:33 AM
RME
And what about this?

Those trucks sure look funny, am I seeing things or is one wheel smaller than the other? Since your link went to a "DH2" reference my wild guess is that this is a DH1 (gotta have 1 before 2, but apparently not 2 before 3...).
On another note, could the GMDH-3 have been named for its 3 axles?
Greetings from Alberta
-an Articulate Malcontent
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Posted by Miningman on Monday, July 24, 2017 1:03 AM
Well half a loaf does have 3 axles so maybe! There may not be a -2.
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Posted by RME on Monday, July 24, 2017 1:15 AM
SD70M-2Dude
Those trucks sure look funny, am I seeing things or is one wheel smaller than the other?
Good eye! (And the small wheels have no power to them, either).
Now tell me how the engine in the 'other' link differs from a SW-8...
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RME
Now tell me how the engine in the 'other' link differs from a SW-8...
Hydraulic transmission instead of a main generator and traction motors.
Greetings from Alberta
-an Articulate Malcontent
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Posted by RME on Monday, July 24, 2017 1:57 AM
Exactly so.
EMD had diesel-hydraulic experimental locomotives considerably earlier than GMD. This is the reason you see "GMDH-1" instead of just DH-1 for the locomotive type miningman cited: the locomotive with the different-sized wheelsets was EMD's "DH-1", from 1951. This had Allison transmissions driving just the outer sets, with the inners as idlers, like an inside-out RDC.
The second locomotive was intended as a full switcher replacement, and is DH-2 (but note, not GMDH-2). Here are a couple of 'better' pictures:


Note the early use of Flexicoil-style trucks, and the evidence that a 'standard' 900hp 567 was used as the powerplant. Note also that EMD is promoting 'hydraulic drive' in the display. I am still looking for a 'free' version of the technical descriptions of this transmission.
Pictures of this locomotive are relatively rare, because (as I understand it) after the demonstration runs were complete locomotive 105 was rather promptly converted back to diesel-electric, and then used at EMD as a plant switcher. Between those two pieces of information, it's pretty clear that the approach that was used Did Not Work Very Well. (I have my suspicions what some of the issues were...)

Note the tell-tale truck swap.
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RME
I have my suspicions what some of the issues were...
Do tell. Great photos too
Greetings from Alberta
-an Articulate Malcontent
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Posted by rcdrye on Monday, July 24, 2017 7:00 AM
Pretty sure the DH-2 a Voith transmission, similar to the type use more or less successfully on DB and BR in Europe, and later on the K-M and Alco diesel-hydraulics. I don't think EMD engineers respected the torque curve for the 567, resulting in a sluggish start with a tendency to overheat the transmission.
I'm sure the bolster was offest for those "Maximum Traction" trucks on the DH-1.
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