Southern Pacific 4-8-8-2 4294's Owner

[Pneudyne]

Thanks.  I was working from memory – probably unwise when one is the same age as old people - so I went back and checked several sources on hand.

 

The Railway Age 1929 December 29 article on the NP 2-8-8-4 stated that the Colstrip sub-bituminous coal as mined varied between 24.6 and 30% water content, 11.9 to 14% ash.  It had a heating value of 6208 to about 7000 BTU/lb, and that when dried, the heating value was about 10 000 BTU/lb.

 

Frey and Schrenk (NP Super Steam era) said only that the Rosebud coal had about half the heating value of eastern bituminous coal, and about 65% that of the Red Lodge coal, without giving numbers.  (They also recorded the connection of the NP 2-8-8-4 to the D&RGW 2-8-8-2.

 

F.A. King (DM&IR Locomotives) compared the DM&IR 2-8-8-4 with the WP 2-8-8-2 from which it was derived.  He noted that the 125 ft² grate area of came about because it was intended to burn eastern soft coal with a heat content of 13 500 BTU/lb.

 

The 12 000 BTU/lb number for the coal used by the SP 2-8-8-4 came from the Railway Mechanical Engineer 1940 January article on that locomotive.  It was described as a low grade bituminous coal.

 

Another number is 11 800 BTU/lb for the coal used by the UP, noted in the Railway Mechanical Engineer 1942 October article on the “big” Challengers.  These look as if they were basically the Big Boy design slideruled down to around three quarters size.  On the other hand, the step from the “small’ Challengers to the Big Boy was more conceptual in nature, with probably quite a bit of ab initio thinking in respect of the design details and proportions.  The D&H 4-6-6-4 was an updated version of the original design, so the three “Challengers” (D&H, UP eight-coupled and UP “big”) make for an interesting comparison.

 

Returning to the AC-9, as a reversed version of the AC-8, it traced back to the AC-4 of 1928, which according to Church (Cab Forward) was an enlarged development of the Mt [4-8-2], F [2-10-2] and SP [4-10-2] classes, rather than a progression from the earlier articulateds.  The SP 4-10-2, derived from the F, had a four wheel pilot truck because that was required to carry the weight of the three-cylinder power assembly.  The same requirement applied to the UP 4-10-2, derived from its 2-10-2, which was slightly smaller than the SP F (which in turn was around USRA heavy size).  From the 4-10-2 UP derived the 4-12-2, albeit it was probably more a conceptual than a simple stretch, and the “little” Challenger was conceptually a “bent” version of the 4-12-2, although with some dimensions carried across.

 

One perspective on the perceived relative utility of the various articulateds embraced by this discussion is provided by the fact that the WP considered acquiring the 4-8-8-4 type for operation over Wendover Hill at the eastern end of its route, displacing its existing 4-6-6-4 fleet.  It was already operating its 2-8-8-2 type through Feather River Canyon.  So for Wendover Hill, it could have acquired more of these (albeit coal burning), or perhaps the derived DM&IR 2-8-8-4 design, which was in process at the time of the deliberations.  But evidently, on a “horses for courses” basis, it saw the 4-8-8-4 type as being a better fit than either the 2-8-8-2 or 2-8-8-4, enough to offset the loss of standardization .  Presumably, that had something to do with the realizable maximum road speeds – limited in the canyon, but less so in the east.  In the event, wiser counsel prevailed, and the answer was “none of the above”, but rather EMD FT diesels.  (Although I understand that the WP did borrow some of the DM&IR 2-8-8-4s for operation in the Canyon during one or more of the winter seasons.)

 

 

 

Cheers,

[Erik_Mag]

Pneudyne

The NP 2-8-8-4 was about the same general size as the DM&IR locomotive, but a sideways step away from the curve because of its “oversized” firebox, required to burn the rosebud coal (under 7 000 BTU/lb, I think).

IIRC, Rosebud coal has a higher BTU content than that, as under 7,000 sounds more like lignite as opposed to semibituminous. I've been to the Colstrip mine formerly used by the NP, with the 1923-24 still operating in 1971. NP's interest in opening the Colstrip mine was that the Red Lodge coal seams were getting mined out and the NP also wanted a much more mechanized mine than possible with an underground mine.

Rosebud coal is pretty soft, and using standard grates would result in a large portion of the coal going u the stack before it got a chance to burn. The grates on the NP locomotives had much smaller air holes and thus required a larger grate to compensate. This is somewhat similar to the Wooten firebox used to burn anthracite waste left over from the sorting process.

[Pneudyne]

Overmod

Now add a good picture of a Southern Pacific AC-9...

steamlocomotive.com calls these "Yellowstones", based strictly on the Whyte wheel arrangement.  They are not the same thing as other deep-firebox Yellowstones, however.

I'm badly tempted to call this a 'reverse cab-forward' design, but...

 

 

Although perhaps the SP AC-9 was not too far off the “curve” when it came to the 2-8-8-4 set.

 

If one does a broad and very simple comparison with the DM&IR and B&O 2-8-8-4s, then it generally fits between them.  Very roughly they are scaled according to their respective driving axle loads, roundly 60 000 lb for the B&O, 66 000 lb for the SP, and 70 000 lb for the DM&IR.

 

The NP 2-8-8-4 was about the same general size as the DM&IR locomotive, but a sideways step away from the curve because of its “oversized” firebox, required to burn the rosebud coal (under 7 000 BTU/lb, I think).

 

All had their fireboxes spread over the two rearmost driving axles as well as over the trailing truck.  The SP, B&O and DM&IR models had short wheelbase trailing trucks, 60 inches for the SP and DM&IR, 54 inches for the B&O.

 

At first glance, the SP, with 139 ft² grate area, looks out of sequence as compared with the 117.5 ft² and 125 ft² for the B&O and DM&IR.  But it had to burn coal that at 12 000 BTU/lb, was probably of lower heating value than that used by the other two roads.

 

Also, the DM&IR might be more of the outlier here.  It was allegedly derived from the WP 2-8-8-2, which had a 145 ft² grate area (although notional, as it was an oil burner).  The DM&IR had a six inches longer firebox, at 210 x 102 inches, than the WP, so I think it is reasonable to assume that the chosen grate area was that which was considered optimum to burn the available fuel.  The WP had around 64 000 lb on the trailing axle, so that any addition at the back end, or any weight growth in general, was going to require an extra axle on the trailing truck if the driving axle load was not materially increased.

 

As a light-hearted aside, is this the only case where the superpower (must be, has a four-wheel trailer) derivative had a smaller grate area than its non-superpower (can’t be superpower, does not have a four wheel trailer) progenitor.

 

Also allegedly, the NP was a derivative of the D&RGW 2-8-8-2, with firebox enlarged from 218 x 108 to 266 x 114 inches, and grate area from 136.5 to 182 ft², which clearly demanded the use of four-wheel trailing truck.

 

Thus one could say that the AC-9’s origins as a “reverse” version of the AC-8 cab forward did not result in its being a major anomaly amongst the 2-8-8-4 group.  It was though around 30 000 lb heavier, most of that increase on the trailing truck.  If one goes back to the SP AC-4 of 1928, it might be argued that it was a 4-8-8-2 primarily because SP had found that a four-wheel centre-pin leading truck was highly desirable on cab-forward articulateds, where the truck acted on a relatively short moment arm.  And that had a conventional layout been acceptable it might have chosen a 2-8-8-2.  But it does look as if SP took some advantage of the extra carrying axle as it were, and sized the firebox accordingly.  Roughly the four-wheel centre pin truck might have been equated with one-and-a-half two axle trailers.  Anyway, there was enough margin for the AC-9, when its time came, to be a reasonable fit to the 2-8-8-4 curve.

 

 

Cheers,

[kgbw49]

Overmod

Now add a good picture of a Southern Pacific AC-9...

steamlocomotive.com calls these "Yellowstones", based strictly on the Whyte wheel arrangement.  They are not the same thing as other deep-firebox Yellowstones, however.

I'm badly tempted to call this a 'reverse cab-forward' design, but...

 

Just added a link in the prior post with the eight-coupled Challenger to the SP 3800 builder's photo.

Just an opinion but these do look the most like a reverse Cab Forward, at least to me.

They could almost have a monkey deck on the front.

SP probably went to Lima with their latest 4-8-8-2 specs and said "We want this but want to use local coal for the Tucumcari line". So that requires a stoker and a stoker requires the firebox on the back end.

[Overmod]

BaltACD

 

Overmod

Now add a good picture of a Southern Pacific AC-9...

I'm badly tempted to call this a 'reverse cab-forward' design, but...

Wouldn't that be a 'cab backward' design?

"Camelrump" came to mind too.

[BaltACD]

Overmod

Now add a good picture of a Southern Pacific AC-9...

steamlocomotive.com calls these "Yellowstones", based strictly on the Whyte wheel arrangement.  They are not the same thing as other deep-firebox Yellowstones, however.

I'm badly tempted to call this a 'reverse cab-forward' design, but...

Wouldn't that be a 'cab backward' design? 

[Overmod]

Now add a good picture of a Southern Pacific AC-9...

steamlocomotive.com calls these "Yellowstones", based strictly on the Whyte wheel arrangement.  They are not the same thing as other deep-firebox Yellowstones, however.

I'm badly tempted to call this a 'reverse cab-forward' design, but...

[kgbw49]

Eight-coupled Challenger:

https://www.railarchive.net/bigboys/up4007-1.htm

Reverse Yellowstone:

http://espee.railfan.net/nonindex/steam-02/4154_sp-steam-ac07-byron_bostwick.jpg

SP Cab-backward builder's photo courtesy of Richard Leonard:

https://www.railarchive.net/randomsteam/sp3800.htm

[Overmod]

kgbw49

Here is a reverse 4-8-8-2 for comparison.

A much more apt comparison is between the cab-forwards and the eight-coupled Challengers* -- these both have the same arrangement of a small weight-bearing guide truck under the end of the firebox, but two driver pairs under the firebox, too.  

Any 2-8-8-4 has a full deep firebox over a trailing truck... which would be too heavy for even an outside-bearing truck of the type we see.

 

*There may be some who don't get this reference without a little careful reflection...

[kgbw49]

Here are several reverse 4-8-8-2 locomotives for comparison all day with some broadside images of 4-8-8-2s.

https://www.steamlocomotive.com/whyte/2-8-8-4/USA/photos/dmir221-gallagher1.jpg

https://www.steamlocomotive.com/whyte/4-8-8-2/USA/photos/sp4216-hechtkoff.jpg

https://www.rebelrails.com/index.php?l=product_detail&p=3324

https://www.railarchive.net/randomsteam/sp3800.htm

https://www.railarchive.net/randomsteam/sp4114.htm

https://www.railarchive.net/randomsteam/dmir235.htm

[kgbw49]

Correct. The City of Sacramento does not own 4294.

The museum, which is located in Sacramento, owns 4294.

And the museum is a State of CA museum so ultimately the State of CA owns the 4294.

If you look at the link that gives the list of the equipment it gives a description of how they acquired each piece of rolling stock.

I used to live in Sacramento and saw 4294 many times. It is an impressive machine.

[SPer]

the city of Sacramento doesn't own the 4294

[kgbw49]

The California State Railroad Museum in Sacramento.

https://www.californiarailroad.museum/index.php

https://www.californiarailroad.museum/assets/downloads/CSRM-Public-Roster-September-10-2020.pdf

 

[SPer]

Who owns Southern Pacific Cab Forward 4294