[N&W] Re: Y-6 Pulling Productivity

[nw-mailing-list at nwhs.org]

 > In the current issue of the Arrow, Mr. King states in his article on the
 > Basics of Steam, Part 2, that "the rating of the Y-6 on a 1% grade was 350
 > tons more than Big Boy."  My questions are: how was this determined and
 > where is it documented?  And - is this simply in terms of pulling capacity?

Without digging into references, the Big Boy -- while a fine machine was the
beneficiary of the awesome P.R. machine at U.P. HQ. Thus the superlatives,
"largest in the world," etc. While such a debate can be argued endlessly,
off the top of my head it seems safe to say that the Big Boy was designed
for hauling fast freight over relatively easy topography, at least as
compared to the N&W's ridgebacks. A block of reefers weighs a lot less than
a drag of 100-plus loaded hoppers. One was built for moving tonnage; the
other for maintaining 50 mph-plus speeds over long distances.

Andre Jackson and/or Lisa Burrows
Ducking as the purists correct me no doubt...
_______________________________________________________________
 >>Taken at face value, this seems an astonishing
 >>fact - and a definite triumph of superior engineering design and locomotive
 >>construction!
 >
Back to the realities of Y-6 vs. Big Boy:

An examination of the horsepower curve of Big Boy - also published in
Kratville's book, established by dynamometer measurements, discloses that
the 4-8-8-4 developed a maximum dbhp of 6290 at 41 MPH.

If you back down the curve to 25 MPH, Big Boy develops a dbhp of 5300.

If you examine the horsepower curve of the Y-6, you will see that it tops
out at 25 MPH and slopes downward as speed increases.  You will also see
that the maximum is 5300, the same as Big Boy at that speed.

The astounding things about this disclosure are that (1)-Y-6 weighs 160,000
pounds less than Big Boy and (2)-Y-6, through the use of compounding, does
the trick with a boiler equivalent in size to that of a 4-8-4.  This fact
was first brought out by Bud Jeffries, who takes notice of such things.

It was pointed out that Big Boy was designed to different parameters than
was the Y-6, but an examination of the service of these locomotives doesn't
show that much difference.  Big Boy was designed to haul tonnage up Wahsatch
and Sherman at about 25 MPH, and be able to drift down the other side at 50
MPH.  This is how the locomotive was used.  The horsepower developed at
higher speed was wasted.  When Big Boy was going 41 MPH, it was usually
downhill with the throttle closed.  There was little need for that 6290 dbhp
and little use made of it.

In the late 'teens or early '20's, some of the railroads had complained that
their Mallets wouldn't run fast enough, and the finest engineering brains
north and west of Roanoke decided that the only thing to do was ditch the
compounding feature and make simple articulateds out of them.  Roanoke
decided that they could refine the compound and speed it up, and they did,
in many stages over 35 years - the end result being the improved Y-5 & Y-6
that could produce mountain Gross Ton Miles per Train Hour per Dollar at a
greater rate than any other mountain steam locomotive ever built.  And, as
stated above, at an engine weight of a little less than 306 tons and with a
boiler roughly the same size as that of a Class J 4-8-4.

Hope this is a further help.

As far as the Alleghany is concerned, it was not, as Huddleston maintains, a
mountain locomotive, and as a flatland locomotive was much less productive
per dollar than the C&O T-1 2-10-4.  A couple of years ago, Huddleston had a
very telling story in TRAINS about its design.  It was an ego trip for the
head of C&O's Advisory Mechanical Committee, who knew that, no matter how
overweight or overdesigned a locomotive was, the C&O would buy it on the
AMC's recommendation.  The top management of the C&O didn't know a steam
locomotive from a paper clip, and it was well demonstrated over the
railroad's history that they'd buy anything.  So they bought the 2-6-6-6.
Several times, for a total of 60.  And the VGN, under an ex-C&O president,
bought more.
It was specifically designed to top the dbhp output of the A.  It did, but
at a cost of $100,000 per engine more, and an engine weight of 200,000 more.
(See chapter 7 of "The A - N&W's Mercedes of Steam).


EdKing
_______________________________________________________________
 >years ago. Around 1940, when ALCo was at the top of their game, producing
 >the Challengers and the Big Boys for the UP, as well as the Niagaras for the
 >NYC, someone asked them if they had anything in mind for the N & W.
 >According to the story, the answer was "why-what the h--- could we tell
 >them about steam engines ?"

This quote actually came from a Lima designer - or maybe a salesman - when
asked if a Lima design for a double-Belpaire boiler/firebox combination had
been offered to N&W.
Not Alco . . .

EdKing
_______________________________________________________________
 > If you really want to lord it over UP fans, compare the Challenger (4-6-6-4)
 > to the A (2-6-6-4). The driver diameter is nearly the same, 69" vs. 70 
", the
 > starting T.E. #'s favor the A by 14,000 pounds; and both were used as
 > horsepower machines;
 > hauling heavy loads at main line speed of 50 mph and above. But - the A did
 > it with 85,000 pounds less locomotive weight !

With two locomotives which are Identical except for wheel diameter, the one
with the SMALLER wheels will pull more. This has to do with the amount of
surface area contacting the rails. That¹s why a C&O 0-10-0 is so powerful,
and why the N&W built M2's, the heaviest 4-8-0's on those itty-bitty
drivers. Fast is another story.

Mark Lindsey
_______________________________________________________________
 > Superior design and construction - yes. It's time to pass on a story I heard
 > years ago. Around 1940, when ALCo was at the top of their game, producing
 > the Challengers and the Big Boys for the UP, as well as the Niagaras for the
 > NYC, someone asked them if they had anything in mind for the N & W.
 > According to the story, the answer was "why-what the h--- could we tell them
 > about steam engines ?"

N&W had something that few other railroads could produce. A railroad
'System'. They designed the engines for the max grades and minimum
curvature in the areas they would be used. They had it down to a science.
They looked at all the time stuff sat, and figured a way to reduce the
sitting time.
The auxiliary water tank saved the stop, and the time NOT at speed, picking
up BIG profits for on-times.
They used long house style engine facilities so an engine was turned in 45
minutes instead of hours.
The Y6 design was a modified USRA design based on the Y2's... Many years of
improvements in power and availability made it the most powerful, but cheap
to run engine in the mountains. Diesel engine companies still use it as the
standard to beat.
N&W paid careful attention to grades and curvatures. The N&W had excellent
track maintenance back then.

Mark Lindsey