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Comparing The Challengers

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  • Member since
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Posted by Pneudyne on Tuesday, February 6, 2024 7:54 PM
 
Kratville, in his book on the UP Challengers, said the following in respect of the six 'diverted' to the DRGW:
 
‘The Union Pacific applied in late 1942 for the 3975-3999 series, the engines being finally delivered in mid-1943.  The road desired more units but that is the most the W.P.B. calculated could be put through Alco in the light orders for other roads.
 
‘At the same time, the W.P.B. was assisting the Denver and Rio Grande Western gear up for the eventual Pacific Theatre operations transportation shift and added six additional Challengers to the U.P. order.  The D.&R.G.W. made it clear that it probably would not want the six units after the war particularly because of having to keep parts in stock for just six locomotives.  The Union Pacific did not offer to take them either since by this time Jabelmann was already laying out his own plans to dieselize the road right after the war.’
 
Thus, it looks as if it were predetermined that the DRGW would not keep these locomotives beyond the end of WWII.
 
 
Cheers,
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Posted by Pneudyne on Tuesday, February 6, 2024 8:52 PM

II Phrogs

How did the relatively poor quality coal used by the Northern Pacific impact their performance, and by extension did the conversion to oil for the SP&S locomotives give any advantage or boost to their performance? 

 

 

Nominally at least, one might reasonably expect that the much larger firebox volume and grate area of the NP 4-6-6-4, as well as other changes such as in the type of grate used, as compared with the UP original, was intended to compensate for the poorer quality coal used by the NP.  Whether in practice it  under- or overcompensated is unknown.  Possibly it did both, at different points in the power vs speed curve.
 
With oil firing, grate area is a meaningless parameter.  Firebox volume and firebox length appear to be more important.  Nonetheless, most oil fired locomotive fireboxes seem to have been designed with possible conversion to coal firing in mind, so that a notional grate area was typically quoted anyway.
 
Many of the UP Challengers were converted to oil firing.  None of the available information suggests that there was any differentiation between the oil-fired and coal-fired versions in terms of load schedules or expected end-to-end speed performance.  A reasonable inference is that in oil-fired form, the firebox and draughting details were chosen generally to match the coal-fired form in overall performance, notwithstanding the higher heating value of the fuel oil, say around 18 000 BTU/lb as compared with the 11 800 BTU/lb of the coal used by the UP.
 
Possibly the SPS oil-burning Challenger were setup to more-or-less match those on the NP.  The NP rosebud coal was said to have a hearing value in the range 6200 to 8000 BTU/lb ex mine, 10 000 BTU/lb when dried.  (Was it dried before use?)
 
A different view was expressed by LeMassena in his book ‘Articulated Steam Locomotives of North America’.  Therein he said: ‘It is little recognized that these SP&S articulateds were among the most powerful steam locomotives ever constructed, and they were able to deliver more power than those of the NP because the latter burned a low grade of coal instead of oil.’  One supposes that LeMassena had quantitative evidence to support that statement, and did not simply infer it from the relative fuel heating values.
 
An interesting case was the WP 2-8-8-2, built as an oil-burner, but said to have a notional grate area of 145 ft².  The firebox was 204⅛ inches long x 102¼ inches wide.  The same design was used as the basis for the DM&IR 2-8-8-4, which burned coal with a heating value of 13 500 BTU/lb.  Here the firebox was slightly longer, at 210 inches, but the same width.  But the grate area, presumably chosen to suit the coal used, but also to allow the use of a Gaines wall, was 125 ft²; it did not occupy the whole firebox length.
 
 
 
Cheers,
  • Member since
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Posted by Pneudyne on Thursday, February 15, 2024 6:19 PM
 
Kratville, in his book on the UP Challengers, said the following in respect of the six “diverted” to the DRGW:
 
‘The Union Pacific applied in late 1942 for the 3975-3999 series, the engines being finally delivered in mid-1943.  The road desired more units but that is the most the W.P.B. calculated could be put through Alco in the light orders for other roads.
 
‘At the same time, the W.P.B. was assisting the Denver and Rio Grande Western gear up for the eventual Pacific Theatre operations transportation shift and added six additional Challengers to the U.P. order.  The D.&R.G.W. made it clear that it probably would not want the six units after the war particularly because of having to keep parts in stock for just six locomotives.  The Union Pacific did not offer to take them either since by this time Jabelmann was already laying out his own plans to dieselize the road right after the war.’
 
Thus, it looks as if it was predetermined that the DRGW would not keep these locomotives beyond the end of WWII.
 
 
Cheers,
 
 

 

 
 
Returning to the DRGW six Alco Challengers, ‘Train Shed Cyclopedia (TSC) #45’ has a tabulation of steam locomotive orders and deliveries from 1939 onwards.  It shows that DRGW placed an order for six 4-6-6-4s from Baldwin in 1942 May, but that this was not approved by the WPB.  An alternative order for six Alco 4-6-6-4s was shown as placed in 1942 June, and approved by the WPB.  The UP order for 25 was shown as placed in 1942 February and approved by the WPB.
 
The UP “big” Challenger was a substantially new design, but it had slipped in before the WPB constraints were applied.  TSC #45 shows that the initial order for 20 was placed in 1941 May for 1942 delivery.
 
If one wanted to make a broad classification of the Challengers by basic design and builder, then the following, with arbitrary numbering, might work:
 
Alco type 1A                 1936                 UP, WP
Alco type 1B                 1940                 D&H, Clinchfield
Alco type 2A                 1936                 NP, SPS (earlier)
Alco type 2B                 1941                 NP, SPS (later)
Alco type 3                   1942                 UP, DRGW
 
Baldwin type 1              1938                 DRGW
Baldwin type 2              1940                 WM
 
 
Some of the Challengers were described in ‘Railway Age’ and ‘Railway Mechanical Engineer’ articles at the time of their appearance.  Known such articles are:
 

UP 'Small'

RA

1936   December 19

pp.900-903

UP 'Small'

RME

1937   January

pp.1-7

NP

RA

1937   March 06

pp.389-391

NP

RME

1937   April

pp.160-163

DRGW

RA

1938   July 09

pp.42-44,70

DRGW

RME

1938   September

pp.323-329

D&H

RA

1940   August 10

pp.207-218

D&H

RME

1940   September

pp.337-344

WM

RA

1941   January 25

pp.209-215

WM

RME

1941   February

pp.45-52

UP 'Big'

RA

1942   October 03

pp.516-519

UP 'Big'

RME

1942   October

pp.413-417

       

 

As I think is well-known, both journals are available at the Internet Archive, RME under its later name of ‘Railway Locomotives and Cars’.

 

https://archive.org/details/pub_railway-age?sort=-date&and%5B%5D=year%3A%221937%22

 

https://archive.org/details/pub_railway-locomotives-and-cars

 

 

 

Cheers,
  • Member since
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Posted by Conductor_Carl on Thursday, March 14, 2024 8:39 AM

Bringing this thread back a little bit, does anyone have the unit costs of these? I've seen some numbers thrown around for NP Z-6's (185,000 ish) the UP CSA-1's (130,000 ish) and the last UP Challengers (225,000 ish) but apart from the Z-6 I dont really have faith in these numbers. Would be interesting to see how costs stack up. 

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