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GP69

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Posted by Leo_Ames on Tuesday, February 25, 2020 9:33 PM

That's not the 2 axle radial truck that Trains said EMD developed. I don't even think it qualifies as a radial truck and it certainly was never meant to go under a Geep.

Looking around the internet, a Trainorders post makes it sound like a 2 axle radial truck was road tested in the mid 1980's.

https://www.trainorders.com/discussion/read.php?18,4647590

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Posted by SD70Dude on Tuesday, February 25, 2020 9:13 PM

oltmannd
Leo_Ames
I wonder had this been built, if it would've rode on their radial B-B truck that Trains Magazine once said had been designed (But I believe never tested). 

It was tested.  Lots of info on this thread 

http://cs.trains.com/trn/f/741/t/150535.aspx

Hot link

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Posted by oltmannd on Tuesday, February 25, 2020 8:51 PM

Leo_Ames
I wonder had this been built, if it would've rode on their radial B-B truck that Trains Magazine once said had been designed (But I believe never tested). 

It was tested.  Lots of info on this thread 

http://cs.trains.com/trn/f/741/t/150535.aspx

 

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Posted by Overmod on Tuesday, February 25, 2020 4:02 PM

Leo_Ames
In the mid 1990's, EMD was pushing their radial truck as a major advance. So I suspect had there been a GP70 family, some may have rode on radial trucks.

If I remember correctly, there was something about the 70-series that was *just* heavy enough that it wouldn't translate effectively to four-axle without high relative axle loading.  If I remember correctly it was a combination of the cooling system component weight and required length to accommodate it effectively.

Two-axle radial steering is not a fun thing geometrically.  On the C truck you can have the center axle as the reference position, and the other axles steered with levers as with radiating axles.  On a B truck you need to use the truck frame as a reference relative to the carbody, and there's a certain amount of unsprung mass from the steering arrangements over what makes for best suspension performance; the Europeans tried a couple of approaches but not with what I'd call particular success over just good lateral.

I have looked for some time to see what actual detail-design drawings for the EMD radial B truck might have been developed.  The patent drawings I've seen aren't particularly convincing as a high-speed improvement over what a good three-axle radial-steering setup can provide.  I would be delighted to find out that something good was actually worked out.

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Posted by Leo_Ames on Tuesday, February 25, 2020 3:28 PM

I wonder had this been built, if it would've rode on their radial B-B trucks that Trains Magazine once said had been designed (But I believe never tested). 

In the mid 1990's, EMD was pushing their radial truck as a major advance. So I suspect had there been a GP70 family, some may have rode on radial trucks.

We'll obviously never know for sure, but I'd be curious if it was in any of the proposals if there was serious conversation here about a GP69 between the Alaskan Railway and EMD. 

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Posted by SD70Dude on Saturday, February 22, 2020 8:38 PM

Would the current SD30C-ECO series rebuilds qualify as a SD69?

UP called their original batch SD59MX's, as they were rebuilt from SD60M's.

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Posted by Overmod on Saturday, February 22, 2020 7:56 PM

IA and eastern
What would it take to make A GP60 into a GP69.

I believe you'd derate a "GP70", or more precisely use the systems of a -70 series with a turbo 12-710 or equivalent for the lower power.

They bought SD-70s instead - with the radial trucks they are actually better on curves than something with B trucks, and the added weight of the HEP equipment posed less of an issue.

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Posted by Leo_Ames on Saturday, February 22, 2020 1:43 PM

That's a new one on me. Was this before they tested out radial C-C trucks and bought the SD70MAC's?

If I had to take a guess, it would've been a GP59 updated with the advancements made with the 70 series.

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GP69
Posted by IA and eastern on Saturday, February 22, 2020 1:25 PM

The Alaskan railroad asked about GP69s. What would it take to make A GP60 into a GP69.

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