ATSF 50/50A technicality

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ATSF 50/50A technicality

Postby Allen Hazen » Thu Apr 07, 2011 9:01 pm

According to Kirkland's "The Diesel Builders, volume 2: Alco" the traction motor used on Alco Dl-10X units (this is the pre-PA, "Needlenose," passenger design) with the high-speed, 58/25, gear ratio was the GE 730. (The GE 726 motor was used on 80 mph "dual service" units of these models: over three quarters of the total production run, given that the New Haven's sixty units had this option.) On the other hand, the ATSF roster published in "Extra 2200 South" (the relevant part was in issue #130 of 2007) says that 50 and 50A, though having 58/25 gearing, had GE 726 motors.

Are there any ATSF locomotive historians out there who can cast light on this?

(I can ***imagine*** an explanation-- the two units were originally equipped with 730 motors, but this was an unusual type: I have never seen any reference to it being used on any locomotives other than the purely passenger Dl-10X. The 726 was probably more available: it was used on the majority of Dl-10X, on Alco HH-1000 switchers, and apparently on some early, 1946-built, locomotives with Alco 244 engines. So, when the motors on 50 and 50A came due for replacement, ATSF used the more available 726 motor instead of the original design. But this is speculation, and I'd be interested in any more
credible information anyone has.)

(This and related topics have been discussed, a while ago, on the Alco forum, but without conclusive answers to a number of questions.)
Allen Hazen
 
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Re: ATSF 50/50A technicality

Postby SSW9389 » Tue Apr 26, 2011 9:23 am

Allen: There is an account in John McCall's Early Diesel Daze about the 50's only trip out west with the Super Chief in 1941. It seems the train stalled on Raton Pass with a steam helper. The steam helper was used on trips over the Pass with EMC diesels and made it. The trip made with the #50 set stalled at the same speed. This suggests that the lighter duty GE motors were installed. ". . . Long before the top of the hill, 50's traction motors were smoking badly...the Super Chief ground to a halt and the maintainer crawled underneath the locomotive. There wasn't "too much solder laying around" so the journey was resumed...with the steam helper doing a larger share of the work than was customary with Electro-Motive Diesels up Raton Mountain. The 50 continued on to Los Angeles and back again with the Super, never again to venture into the mountains of the transcontinental route." . . .see page 113.

IMHO the 50 set was built with the lighter motors and then rebuilt with the 726 motors at a later date. The 726 motor seems to be the big difference between the DL109/DL110 and the earlier DL103, DL105, DL107, and DL108 units.

Ed in Kentucky
COTTON BELT: Runs like a Blue Streak!
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Re: ATSF 50/50A technicality

Postby Allen Hazen » Wed May 04, 2011 8:36 pm

SSW9389--
Thanks, Ed! I've never seen that book, and the story certainly is suggestive.
As for whether the 730/726 motor difference was a major part of the distinction between Dl-109 and 105/107...
According to Kirkland ("The Diesel Builders, v. 2: Alco"), only the 730 was used in units geared for top speeds over 80 mph (most non-New Haven units, in what in most cases must have been gross overoptimism about the speeds attainable on existing track!), and the 726 and 730 motors used different gear ratios for the 80 mph top speed. Elsewhere (article in one of the smaller-circulation model railroad magazines) I have seen a list of the gear ratios used on Alco Dl-10X units. Putting these two sources together suggests that even some very late units (Southern's second order, built after the first New Haven Sl-109) had the 730 motor, and that the GM&O's first units (built very early in the series) had 726. So, it's complicated!
--
We're having insulation installed on our basement, making access to my reference books difficult for the next couple of weeks, but I'll try to get back to you about this...
(Apologies for slow reply: I was out of town and out off computer contact for a bit.)
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Re: ATSF 50/50A technicality

Postby SSW9389 » Sat Nov 08, 2014 8:38 am

Earlier this week there was a discussion on the Santa Fe Listserve about #50L and #50A. The discussion was about whether it was a DL-107/DL-108 set or a DL-109/DL-110 set was started up by me. And some primary source documents were offered up. The Santa Fe Class 50 drawing shows that #50L was built with four GE-730 traction motors, 58:25 gearing and 41 inch wheels. Then another fellow wrote in that there had been a change to that drawing showing it was rebuilt with four GE-726F1 traction motors, with 40 inch wheels. John McCall's book Early Diesel Daze on p.254 shows the characteristics of #50 as 4 GE-726F1 traction motors, with 58:25 gearing and 40 inch wheels. I don't have a date for the rebuild.

I'm going to cross post this to the Alco list. Allen Hazen and I already discussed this bit a couple of days ago, but hopefully he will add to this discussion.

Ed in Kentucky
COTTON BELT: Runs like a Blue Streak!
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