More Articulated Steam Egines please!

[markpierce]

Reference twhite's and my debate above on the reason for the SP four-wheel truck under their backward (cab-forward) Yellowstones.  I received the following from an expert, Bob Church via Tony Thompson (anything in blue is my addition):

Mark Pierce wrote:
> . . . I had believed the SP 4-8-8-2 design was primarily to reduce the
> axle-load on the larger-firebox ACs. What's the answer?

I forwarded Mark's question to Bob Church, who isn't a member of
this list  (SP Yahoo). Here's his reply:

"Some conclusions can be rationally made by looking at the
specification differences between the AC-1, 2, and 3 classes (2-8-8-2s) and the
AC-4s up (4-8-8-2s) . On the bigger classes, the drivers were 63" dia. vs 57"
diameter, which allowed faster speeds, especially with better balancing
capabilities with the disc drivers on the AC-7s up. The big AC's were
pretty much standard on passenger trains in mountainous territories, so
a four wheel truck was necessary to lead trains into curves at
passenger train speeds. That is why all standard passenger engines had
a four-wheel trucks. The centering/lateral motion mechanism of a single
axle lead truck just doesn't have the ability to "lead" an engine into
a curve at higher speeds with safety.

"Note the marked difference in firebox size of the smaller and larger
AC's and it should be evident that support of the weight was also a
contributing factor. (The use of the four-wheel truck under the firebox was retained in 2-8-8-4s of the AC-9 class, the "cab-backward" AC-8.) The bigger also had the weight of a much bigger compustion chamber to support. The WP and Messabe Yellowstones were not
passenger haulers, and were not running firebox forward.

"Weight distribution and better trackability are combined reasons for
the four-wheel lead truck.

Bob Church"


Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com

Mark

[twhite]

heh, been on the hunt for a DM&IR 2-8-8-4, and I finally Ebayed a winner. The Akane, hopefully be here soon. This engine keeps popping up on ebay, and really, the ebay prices have been going about equal to the new plastic stuff except for the newer brass releases.

Some modelmaker HAS to make this engine in the plastic and get DCC and sound into it.

I have a record here with the engine sounds, guys, this baby's a monster with a ghostly whistle! 

 

 

Dinwitty--

I doubt you'll be disappointed in the Akane--it's a big, heavy delicious brute of a locomotive and pulls like a team of oxen.  I've got two Yellowstones (one that I bought in 1965 when they were new), and if you don't mind a little 'coffee-grinder' noise from the gearing, you'll probably be very happy with their pulling power.  Not as beautifully detailed as newer brass, but if you want to improve the castings, you can get better castings from either Cal-Scale or Precision Scale Miniatures (I did, mainly to replace the Worthington FWH with an Elesco).  However all in all, they're one SPECTACULAR loco.  I've replaced the motor on my older one with a NWSL can, however the motor in the newer one (outside frame) is a very smooth runner.  Believe it or not, they CAN negotiate a 24" radius, however they look much better on a 30" or bigger.  I hope you enjoy it.  If not, let me know and I'll be happy to take it off of your hands, LOL! 

Tom

 

its not even in my hands...yet   8-D

gotta build my layout now, a bad excuse is going to arrive. I have a test track tho and the seller said it needs a little work, I am no stranger to doing that, if I can fix the ALCO EL2 broken gears issue, I can do this.

the lead wheels on any engine are to help tracking and lead the engine into curves. If you find the wheels under the firebox they are supporting the firebox, if not, a little more for guiding.

 

Dinwitty--

Working on the Akane's is really simple--4 screws (two above the 2nd cylinder set and two under the cab) and the boiler's off and everything else is right there waiting for you.  VERY simple gearing on the little devil--Akanes were famous for their (then) superior mechanisms.  You should have very little trouble getting it in top shape. 

Enjoy!

Tom

[twhite]

Reference twhite's and my debate above on the reason for the SP four-wheel truck under their backward (cab-forward) Yellowstones.  I received the following from an expert, Bob Church via Tony Thompson (anything in blue is my addition):

Mark Pierce wrote:
> . . . I had believed the SP 4-8-8-2 design was primarily to reduce the
> axle-load on the larger-firebox ACs. What's the answer?

I forwarded Mark's question to Bob Church, who isn't a member of
this list  (SP Yahoo). Here's his reply:

"Some conclusions can be rationally made by looking at the
specification differences between the AC-1, 2, and 3 classes (2-8-8-2s) and the
AC-4s up (4-8-8-2s) . On the bigger classes, the drivers were 63" dia. vs 57"
diameter, which allowed faster speeds, especially with better balancing
capabilities with the disc drivers on the AC-7s up. The big AC's were
pretty much standard on passenger trains in mountainous territories, so
a four wheel truck was necessary to lead trains into curves at
passenger train speeds. That is why all standard passenger engines had
a four-wheel trucks. The centering/lateral motion mechanism of a single
axle lead truck just doesn't have the ability to "lead" an engine into
a curve at higher speeds with safety.

"Note the marked difference in firebox size of the smaller and larger
AC's and it should be evident that support of the weight was also a
contributing factor. (The use of the four-wheel truck under the firebox was retained in 2-8-8-4s of the AC-9 class, the "cab-backward" AC-8.) The bigger also had the weight of a much bigger compustion chamber to support. The WP and Messabe Yellowstones were not
passenger haulers, and were not running firebox forward.

"Weight distribution and better trackability are combined reasons for
the four-wheel lead truck.

Bob Church"


Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com

Mark

Mark--

Good response you got, and it makes a lot of sense.  BOTH tracking and weight distribution.  Hey, I've never decided that I'm too old to learn anything, LOL! 

As an aside, though I love that AC-12 here at the Sacramento Railroad Museum, I sure wish that SP had decided to preserve one of those 'transitional' AC-6's.  Only AC I ever rode in, but I sure have fond memories of that class, especially the 'flat' face.   It was also the first AC with the boiler-front hung 'talking' pumps, and let me tell you, could those pumps carry on a conversation with each other, LOL!

Tom  

[R. T. POTEET]

Reference twhite's and my debate above on the reason for the SP four-wheel truck under their backward (cab-forward) Yellowstones.  I received the following from an expert, Bob Church via Tony Thompson (anything in blue is my addition):

Mark Pierce wrote:
> . . . I had believed the SP 4-8-8-2 design was primarily to reduce the
> axle-load on the larger-firebox ACs. What's the answer?

I forwarded Mark's question to Bob Church, who isn't a member of
this list  (SP Yahoo). Here's his reply:

"Some conclusions can be rationally made by looking at the
specification differences between the AC-1, 2, and 3 classes (2-8-8-2s) and the
AC-4s up (4-8-8-2s) . On the bigger classes, the drivers were 63" dia. vs 57"
diameter, which allowed faster speeds, especially with better balancing
capabilities with the disc drivers on the AC-7s up. The big AC's were
pretty much standard on passenger trains in mountainous territories, so
a four wheel truck was necessary to lead trains into curves at
passenger train speeds. That is why all standard passenger engines had
a four-wheel trucks. The centering/lateral motion mechanism of a single
axle lead truck just doesn't have the ability to "lead" an engine into
a curve at higher speeds with safety.

"Note the marked difference in firebox size of the smaller and larger
AC's and it should be evident that support of the weight was also a
contributing factor. (The use of the four-wheel truck under the firebox was retained in 2-8-8-4s of the AC-9 class, the "cab-backward" AC-8.) The bigger also had the weight of a much bigger compustion chamber to support. The WP and Messabe Yellowstones were not
passenger haulers, and were not running firebox forward.

"Weight distribution and better trackability are combined reasons for
the four-wheel lead truck.

Bob Church"


Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com

Mark

I don't know who this Bob Church is but he's the only guy who's agreed with me in the last six months!!!

[Virginian]

Ken,

You of all people NEED a BLI N&W Class A.  A model of probably the finest reciprocating steam locomotive EVER built.  And the BLI award winning model version will pull 150 cars on the flat and mine scaled a 2% grade, but the grade was only about 13 feet long so the whole train wasn't on the grade at once.

I have 3, and if and when they release the 1238 and up roller bearing version, I will have 4.  I kinda like them.  I also have several of the Proto 2000 2-8-8-2s (started life as N&W Y3s) as well, and while they run like a Swiss watch and you can modify the undec versions with perfect fitting extra parts about 10 different ways, you do need to add weight to get real good pulling ability.

[markpierce]

Here is more expert opinion on why SP's Yellowstones required a four-wheel truck under the firebox:

The weight on the four wheel truck varied from 87,000 lbs. to 72,100
lbs. As the maximum axle loading on the SP during AC days was about
69.000 lbs the four wheel truck was required. But also, as mentioned in
this thread, the four wheel truck gave better tracking around the sharp
mountain curves and also at the 60 mph speeds allowed when the track was
not so curvy. The WP used a two wheel truck under the firebox of the 250
class by allowing enough more weight on each driving axle to keep the
maximum axle loading to 69,000 lbs. and as far as I recall it was the
only railroad to use only a two wheel truck under such a large firebox.
This axle loading restricted the engines to the low speed mountain
crossing Oroville to Portola so a maximum speed of 40 mph or so was
sufficient.

In the era from about 1900 on the SP designed most of their steam
locomotives and had them built to order. Remember the Harriman standard
engines? They were mostly designed by the SP staff. By the 1920s and
1930s the SP, UP, NYC, N&W and some others had engineering staffs that
equaled or exceeded the builder's. As an example, Baldwin had notorious
trouble with counterbalance on 4-8-4s for ACL and 4-6-4s for the NYNH&H
but the SP ACs ran easily at 65 mph with only 63" drivers because the SP
engineered the counterbalance, not Baldwin. The PRR, until the 1920s,
probably had the best staff of all, but then they focused on electrics
and lost focus on steam. Lima had a very innovative engineering staff
and after much argument with the SP's did influence the design of the
later GS classes. And Alco did much if not most of the 4-10-2 design
work. The four wheel truck on those engines was only because of the
extra weight of the three cylinder setup.

Charles Givens

[Heartland Division CB&Q]

NP Z6, Z7, or Z8

Sorry, UP fans, but there are plenty of UP RR 4-6-6-4's already.

[cudaken]

 Virginian, do you have a PIC or a link to the BLI N&W Class A? I need to buy more books on steam.

 First I like to thank all that took time to answer, but even with over 1000 post I still stupid when it comes to trains. Most of the postings was asking for help not answers. So when you  smart Steam folks say a Class A I have no clue to what it looks like!

 Case in point, have been in to Mopar mainly Charger's most people could not tell a 1969 Charger from a 1970 Charger. I on the other hand could list about 40 things + that are close but driffrent. Heck I can tell what year a mirror for a E-body (cuda) was made for. To the trained eye it is easy, but 97% of the people they will look the same. I hope you folks undestand the boat I am in.

 I will all so say I want something that looks driffrent from the Y-6b and Big Boy I have. I am far from being a rivret counter. Much like most people would think a 73 Cuda and a 74 Cuda look's the same! By the way the rarest year for a Cuda was 1974 only around 3000 made.

 Thanks again for all the kind answers. More PIC would be of great help!

 By the way, the Y6 B is the best engine to date! I have yet to find out the max it can pull. 40 cars + and it just creeps around the bench and up the grade with no slowing!

             Cuda Ken