# USAT SD70MAC inquiry



## Ted Doskaris (Oct 7, 2008)

USAT SD70MAC inquiry - a few questions:

Can all reading answer any of the following questions: 


1) Are all production run USAT SD70MAC locos from day one devoid of traction tires on ALL of its wheels?

2) If not, are newer production runs devoid of traction tires? 
(If so, can some form of identification or date be provided in which to distinguish this?)

3) How much does the USAT SD70MAC model weigh?

4) Does this loco include or is it designed to accommodate added extra weights?

5) Are all 6 axles (3 per truck) power driven?

6) What type of bearings does this loco employ to support its drive axles?
(e.g. brass bushings, ball bearings, or other) 

7) How does the USAT SD70MAC speed compare to the Aristo-Craft GE Dash 9?

8) What Kadee couplers are recommended for it?


Thanks in advance & much appreciated,
-Ted


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## Greg Elmassian (Jan 3, 2008)

Kadee:

836 if you are asking G scale Kadees 



* http://www.kadee.com/conv/g1list.pdf*

and an in depth how to:

*http://www.kadee.com/conv/USATrainsSD-70%20MAC.pdf*

All from the kadee site, obviously.

All axles driven, floppy outer axle like other USAT 6 axle locos, allows tighter curves.


There are bearings in the side frames, don't know if they are ball bearings.

I think they do not have traction tires.


Regards, Greg


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## Paul Burch (Jan 2, 2008)

Ted,
On the traction tires. My first two S.P. units from early runs both had traction tires. My new release heritage unit did not.  You may need to check with USA to find out if all new production units will come without traction tires. I'm curious myself if there has been a change at USA about traction tires on just the SD70's or all locomotives.


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## Ted Doskaris (Oct 7, 2008)

Paul,

According to Robby at RLD Hobbies, he is of the belief that all SD70s did not have the traction tires - but as I suspected, you confirmed otherwise. 

Robby checked on a Conrail SD70MAC he happened to have in stock and said it did not include the traction tires.



Of course, I am interested in the SP speed lettered / gray version and don't want to risk ordering one blind sighted, and for now I don't want to contend with retrofitting an earlier production run version with replacement wheels when I could get one already made without traction tires.


When did you get your early production SP SD70MAC locos (year / month)?

Do you think that both your early and late production SD70MACs weigh about the same - and any idea how much?


Thanks,
-Ted


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## aceinspp (Jan 2, 2008)

Ted: The older Mac that I had had traction tires on it. They were on the middle axle only. Newer models as stated should be void of them.

3. I can not give you a weight on it but its fairly light can use some additional weight.



4. It does not come with any addtion weight. Your on your own as to adding and wfhere you want to add the wight. If not doing sound you could add to the fuel tank.

5. All axles are powered.


6. These units have brass bearings that the axles run through.

7. These units run faster than the -9s or E units of Aristo

8. Greg has give you the answer for the Kadees but will take some work.

Later RJD


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## Ted Doskaris (Oct 7, 2008)

Thanks RJ,

The fuel tank is where I would prefer to add weight as this is more important to me than sound, but with brass bushing type bearings I think I would not want to add more than a couple of lbs - and that's OK with me. Is the tank easy to remove form the bottom of the loco to gain access?


As to how the speed of the USAT SD70 is faster than the Aristo 6 axle locos types, do you think it may closer match the speed of Aristo's older & faster 2 axle type locos - like the U25B, for example?


-Ted


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## Bill Swindell (Jan 2, 2008)

I put ball bearings in the side frames of my USAT GP-9. You can do the same to the SD-70.


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## aceinspp (Jan 2, 2008)

Ted the fuel tank is very easy to remove. I believe there is either 2 or four screws to remove. I no longer own mine as I sold it. Later RJD


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## W3NZL (Jan 2, 2008)

Ted, 
The answer to Ur problem is to drop a set of Aristo 3 axle motor blocks under Ur SD-70, or any USA unit with the floppies for 
that matter... In most cases its rather easy and straight-forward to do also, unfortunately its a bit expensive at today's 
prices to do this, I bought a whole bunch of the A-C 3 axle blocks several years ago when the prices were reasonable, and 
have converted all my USA 3 axle units, then sell off the new floppies in the classifieds and its a break-even or better deal...
The nice thing of course is that all my AC & USA 6 axle locos run happily together now... If U got a set of AC motor blocks 
laying around, its a good way to go...
Paul R...


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## Paul Burch (Jan 2, 2008)

Ted,
The stock loco weighs approx 11.25lbs.
The two S.P. units that I have were purchased about the end of 2006 or very early 2007. I don't have the receipt for them but do show I ordered non traction tire wheels for them on 1-7-07. That should be pretty close.


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## Ted Doskaris (Oct 7, 2008)

Thank you Paul R.;

It's good to know of your experience. 


For sometime I have been aware of folks retrofitting Aristo 3 axle motor blocks into the USAT locos, but I am also aware that at least one particular individual did the opposite, too, swapping the "floppy" USAT motor blocks into Aristo SD45s!

I take the view that a customer should be able to successfully run a new loco right out of the box without having to modify it, and I think it most reasonable to retain whatever manufacture provides and try to work with it first. In time, specialized use with other manufactures locos may prove it best to do motor block swapping, but since I wish to avoid a traction tire equipped SD70, any speed differtence should be more forgiving on the motors since the wheels would be allowed to slip some.


In this regard, I conducted a successful experiment with Aristo's own products (when loaded with a train) by doing a multiple lashup of a SD45 with two U25Bs (the U25Bs run faster) Below link:


http://www.elmassian.com/trains-mainmenu-27/ted-doskaris-vignettes-mainmenu-157/triple-heading-aristo-u25bs-aamp-sd45-mainmenu-169 


-Ted


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## Ted Doskaris (Oct 7, 2008)

Posted By Paul Burch on 01/20/2009 2:17 PM
Ted,
The stock loco weighs approx 11.25lbs.
The two S.P. units that I have were purchased about the end of 2006 or very early 2007. I don't have the receipt for them but do show I ordered non traction tire wheels for them on 1-7-07. That should be pretty close.



Thank you Paul, and all.


I recently stopped in a local hobby shop and by happenstance noticed an overhead layout with SP SD70M road number 9812 pulling a train back and forth. Such luck!


As best I could see from the ground looking up through the track ties (maybe 10 feet) I did not see any traction tires (I think normally found on the middle axles of the trucks).


So I got the sales person to look, too. He got a ladder and went up close to the loco - though he did not want to stop the train - and said he could not see any traction tires, either.

Since the newer production runs of the SP gray / speed lettered USAT SD70 are road numbers 9812 & 9813 - it looks like these were factory made without traction tires.









I wonder if any readers of this thread happen to have those USAT SP 9812 & 9813 road numbers and can confirm, too, that they don't have traction tires. 


BTW, I came across some prototype pictures of SP 9812 / 13 SD70s at the below links:

http://www.northeast.railfan.net/images/tr_sp9812.jpg 
http://espee.railfan.net/nonindex/sd70m_photos/9812_sp-sd70m-steve_carter.jpg 
http://www.snowcrest.net/photobob/sd7015.html 
http://www.snowcrest.net/photobob/sd7046.html 
http://www.snowcrest.net/photobob/sd7047.html 
http://espee.railfan.net/nonindex/sd70m_photos/9813_sp-sd70m-ken_perry.jpg
http://espee.railfan.net/picindex/sd70m_walkaround/ck_sd70m-rear-roof.html 
-Ted


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## aceinspp (Jan 2, 2008)

Just for your info Ted I have two SD40 locos that have the same wheel arrangement as the SD 70s. They run great as is and no problem derailing. I did change out the traction tire axles what a difference. I like you can not seeing spending the bucks for a retro fit of AC trucks. Now that I'm on DCC I have no problem with speed differecnces. Later RJD


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## Ted Doskaris (Oct 7, 2008)

Thanks RJ,

I have no intention of retrofitting almost 50 locos to DCC, (cost and time) or using a dedicated trailing car with the electronics, but I wonder how the USAT SD70 operates using Aristo's Pulse Width Control. But I suspect the motor windings will present a similar reactive response like those of Aristo's locos and will likely work (barring any undesirable response from ancillary components).


-Ted


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