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What steam we haven't seen - relaunch Locked

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Posted by daveklepper on Wednesday, June 19, 2013 4:21 AM

At 81, my eyesight, even with bifocals, may not be sufficient, but the previous photo's "tank" looks like a 2-6-4T to me and not a 2-6-6T!     I don't have the photos, but the last time I saw one of the B&A "tanks," I was quite sure it was a 4-6-4T pulling some freight cars on the Grand Junction across Main Street near Vassar Street in Cambridge in the late Spring of 1950 (or 1951?), after the suburban service had been dieselized.

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Posted by NorthWest on Tuesday, June 18, 2013 10:10 PM

I did look at the posts, and I see you have already discussed this. I see now why you are annoyed. Again, very sorry for posting.

NorthWest

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Posted by NorthWest on Tuesday, June 18, 2013 9:41 PM

Got my math wrong, I believe 16 years is correct. Black Eye

I was attempting to respond to Firelock's post above, sorry if I stepped on any toes, I'll stay off this thread from now on... Zip it!

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Posted by Overmod on Tuesday, June 18, 2013 9:17 PM

NorthWest

The Wikipedia article states that the Baltic name actually precedes Hudson, as the first 4-6-4 was supposedly built some 26 years before the NYC version. IIRC, the Milwaukee called their 4-6-4s Baltics.

Look down a few posts.  We have discussed this in far more detail than Wikipedia.  And there is no 'supposedly' about it, although "26 years" is just flat wrong.  Look for the word NORD if you are having trouble finding the posts.

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Posted by NorthWest on Tuesday, June 18, 2013 9:03 PM

The Wikipedia article states that the Baltic name actually precedes Hudson, as the first 4-6-4 was supposedly built some 16 years before the NYC version. IIRC, the Milwaukee called their 4-6-4s Baltics.

http://en.wikipedia.org/wiki/4-6-4

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Posted by Firelock76 on Tuesday, June 18, 2013 8:36 PM

OK Overmod, I'll have to give it to the Canadians, they beat the CNJ to a 4-6-4 type by nine years, so they get the naming rights, especially since no-one can figure out where the term "Baltic" came from. Europe possibly?

I have to dispute that article you provided the link to.  It mentions CNJ having some 2-6-6 tank types, however I'm looking at a CNJ lcomotive roster from 1930 listing all active locomotive types from 1899 on, and there's no mention of a 2-6-6T.  2-6-2T's and 4-6-4T's yes, but no others. 

The locomotive in the picture doesn't look like a 2-6-6 to me, it looks like a 2-6-4.  Maybe it should be called a "Lionel" type!  It IS cool, though!

As an aside, I believe one of those Canadian 4-6-4T's survives in the Steamtown collection, but not in running condition.

Wayne 

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Posted by Overmod on Tuesday, June 18, 2013 8:31 PM

GETTING BACK AGAIN TO THE ORIGINAL QUESTION:

Who has thoughts about the 'logical' evolution of each of the Big Three's approach to steam locomotives? 

I think there is little doubt that more 'commonalty' of parts and procedures for maintenance would have taken place (especially in the 'absence' of Dilworth-Hamilton style OTS technology common to all railroads).  Other than that of the specialty manufacturers ... and even there, all too often it was 'build to suit' or custom adjusted.

I am still amazed that no further developments of the 'automatic cutoff control' from the early Twenties were undertaken.  Something I would think would be a top priority for designers would be automation and effective simplification of controls and systems, specifically in the interest of better performance and better crew efficiency and satisfaction.  Valve Pilot is an illustration of this; so is the 'four corner' pyrometer setup Staufer describes on one of the J3as (5444?)

Just to get the ball rolling:  What approaches to labor-saving machinery would each of the makers have embraced?  Take the application of poppet valves, for example.  Or the adaptation of Besler-style motors and perhaps high-pressure generators to 'lighter' power as well as big four-driving-axle engines...

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Posted by Overmod on Tuesday, June 18, 2013 8:29 PM

GETTING BACK AGAIN TO THE ORIGINAL QUESTION:

Who has thoughts about the 'logical' evolution of each of the Big Three's approach to steam locomotives? 

I think there is little doubt that more 'commonalty' of parts and procedures for maintenance would have taken place (especially in the 'absence' of Dilworth-Hamilton style OTS technology common to all railroads).  Other than that of the specialty manufacturers ... and even there, all too often it was 'build to suit' or custom adjusted.

I am still amazed that no further developments of the 'automatic cutoff control' from the early Twenties were undertaken.  Something I would think would be a top priority for designers would be automation and effective simplification of controls and systems, specifically in the interest of better performance and better crew efficiency and satisfaction.  Valve Pilot is an illustration of this; so is the 'four corner' pyrometer setup Staufer describes on one of the J3as (5444?)

Just to get the ball rolling:  What approaches to labor-saving machinery would each of the makers have embraced?  Take the application of poppet valves, for example.

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Posted by Overmod on Tuesday, June 18, 2013 8:18 PM

daveklepper

Come to think of it, the NYC-B&A had both 4-6-4T's and 4-6-6T's.

So I go to see pictures of NYC 4-6-4Ts, because to my knowledge I've never seen one... and what to my wondering eyes should appear but this, which hits up all the current off-topics in this thread together.

Here's a locomotive called a "Baltic Tank" -- although he says he does not know where 'Baltic' came from! -- and he proceeds at some length to draw parallels with... wait for it... CNJ locomotives of the same wheel arrangement.  Sorry, Firelock, it looks as if the Government has already named your 4-6-4T class for ya!

But darned if I can find either a NYC or B&A 4-6-4T.  Now, 2-6-6 there was:

... and I think I even see a snazzy ATC inductor shoe on that trailing truck.  But even further from a 4-6-4T than the 4-6-6s are.  So I need a reference from Dave, and preferably a picture or link to one.

(I was surprised to find that some Canadian 4-6-4Ts are listed as being over 30,000lb heavier than the 4-6-6s!)

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Posted by Firelock76 on Tuesday, June 18, 2013 5:38 PM

Overmod

[Just for the record, despite what YouTube says, that's Dave van Ronk's 'Garden State Stomp'.  This was the only online version of the original I could find (complete with that oh-so-expressive sigh at the end!) ]

In keeping with the theme of 'Hudson' TANK engines, you might stick to NJ creeks and brooks...

OK, how about Pascack Brook, (the) Saddle Brook, the Tenakill Brook...

Oh, and Dave van Ronks "Garden State Romp"  was interesting, to say the least.  Looks like with 575 municipalities to choose from he didn't lack for lyric material!  Municipal madness indeed!

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Posted by daveklepper on Tuesday, June 18, 2013 8:18 AM

Come to think of it, the NYC-B&A had both 4-6-4T's and 4-6-6T's.

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Posted by Overmod on Monday, June 17, 2013 10:07 PM

GETTING BACK TO THE ORIGINAL QUESTION:

One thing I'd like to see discussed is how each builder's "house style" would have evolved if steam had continued (making whatever other assumptions necessary to create the alternate history we have already brought up, and done to death...)

This dodges issues like the weird financial control of Baldwin, but continues to include their 'distinctive competence' alliances and divisions, notably including GSC.

A few issues to consider:

1)  The distortions of traffic and operations created by the War (which, for example, favored use of Q2s on assured long, heavy, fairly fast consists) would not persist.  We need to consider how the course of 'new' power development would have gone, considering the relative glut of overcapacity 

2) The great mstaken perception that tremendous improvements in passenger volume would be present with 'modern' train improvements.  One thing this produces is a niche for dual-service power, perhaps as large as a double six-coupled engine for some services.  Another is an evolving niche for high-speed passenger power, including designs running substantially faster than 'safe' for two-cylinder quartered reciprocating locomotives...

3) Changes in operating cost associated with VERY large effective wage increases.  

Larger power, we've gotten.  But what about making smaller power more efficient?  I've seen a PRR drawing that has a mechanical B-B drive and a torpedo-boat kind of oil-fired boiler, probably like a Besler car or Sentinel.  Looks like a baby DD2.  A whole class of possibility there, which I think would be greatly increased if a Bowes-drive-like self-exciting coupling were to be introduced with change-speed gearing in something with about the tractive effort of a GP7 and a double-ended carbody.

Versions of this for switching, too.  One great difficulty with steam switching was how the locomotives had to be moved to service them.  Diesel switchers just need a fuel hose, from little more than a heating-oil tank blocked up on some cribbing.  Even a M2 automatic doesn't do much to solve that set of issues.  What do we think would?

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Posted by Overmod on Monday, June 17, 2013 8:52 PM

[Just for the record, despite what YouTube says, that's Dave van Ronk's 'Garden State Stomp'.  This was the only online version of the original I could find (complete with that oh-so-expressive sigh at the end!) ]

In keeping with the theme of 'Hudson' TANK engines, you might stick to NJ creeks and brooks...

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Posted by Firelock76 on Monday, June 17, 2013 7:28 PM

Hi Overmod!  Well, the "New Jersey Stomp" is interesting, to say the least, but in the "Hudson"  vein I'm limiting myself to New Jersey rivers for locomotive names.

Let's see now, "Pompton", "Rahway", "Manumuskin", "Wallkill"...

Wayne

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Posted by Overmod on Monday, June 17, 2013 5:21 PM

Firelock76
No, I'm not giving up!  The "Big Little Railroad" lives!

Well, you got the next best thing 'next door' -- Pocono is the accepted term for the 4-8-4 wheel arrangement in South Australia...  ;-}

But I get the impression you haven't quite found the right names.  Let me help you find some.

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Posted by Firelock76 on Monday, June 17, 2013 5:10 PM

...or a "Ramapo" or a "Pequannock"  or a "Delaware"  or a "Wanaque"  or a "Cohansey"....

No, I'm not giving up!  The "Big Little Railroad" lives!

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Posted by Overmod on Monday, June 17, 2013 5:08 PM

The NORD engines were a good enough precedent for Milwaukee, which innovated the modern 4-6-4 (ugly as it might have been, it was still the first steam locomotive verified over 100mph by an accurate source).  

And let's look at that technical "difference" -- in the only place that 'counts' when determining Whyte coding:  Four-wheel front truck: check.  Six drivers, check.  Four wheels under the rear of the engine, check.  Tender out behind, check.

Next you're going to try to tell me the truck arrangement under the back was not standard?  So now any of the early Atlantics and Pacifics that didn't have a truck at all (just a carrying axle in rigid wheelbase, perhaps with a little lateral motion) aren't actually 'Atlantics' or 'Pacifics'?  Locomotives with narrow fireboxes or non-SuperPower size boilers don't count? 

Do you honestly believe that maintenance workers on railroads refer to locomotives as "Pacifics" or "Hudsons"?  Most of the time they go by letter class, or range of numbers as on ATSF (e.g. the 2900 class) or B&O (5500 class) or NYC ('6000s') to name three I recently saw.  Perfectly unambiguous, and who cares about railfan details?  These are people running trains to make a living.

(This is different from people proud of the name, of course -- but that is not what we were discussing; unambiguous shop reference was.)

Henderson's 'multiplex' patents didn't presume compounding; they only referred to the number of engines under one locomotive.  Although there was little chance of there being enough steam for six whole cylinders -- more on the quads and quints! -- without going to 'using the steam twice' or whatever.  (Remember this guy was involved with the hinged boilers, 4-4-6-2 Mallet express locomotives, 2-10-10-2s, and weird combo superheater/feedwater heaters at this general period.

But a Triplex would have been a Triplex (Henderson triplex, that is), compounding method or not.  (Some discussion over the years on whether the thing could have been made to work with higher boiler pressure, and independent HP and LP cutoff a la de Glehn-du Bousquet to get the expansion ratio to 2.7 or whatever to make the trick work.  I did not hold my breath then, and am not really holding it now.)

Your Triplex is a completely different thing, as like the Henderson idea as the 5001 class was like the four-wheel-trailered 3829.  And even if we stick to Henderson's concept -- your use of the name would be OK. 

Meanwhile (getting back to the topic of '40s steam, albeit a bit sideways) there was that other 'Triplex' controversy, the one that related to Loewy's 'three-box' (as it's called in the automotive world) locomotive design.  PRR liked the idea enough to call the V1 project by that name, all the way up through the Steins patents.  But then Loewy started asking (and he was legendary for asking) where his piece of the action was.  And so the 'triplex' turned into something different...

OK, I'm getting a bit upset:  you are quite right, it ISN"T "WALSCHAERT'S" -- IT'S THE GUYS NAME, WALSCHAERTS, 'A' before 'E', 'S' at the end, and no apostrophe.  And why not use Heusinger's full name if we are going to bring up that 'unfortunate' business.  Gray invented the telephone.  But that was not the name that people know the telephone by in the United States.  Too bad.  Get over it.   ;-}

[In the interests of fair disclosure, yes, I think Heusinger von Waldegg did in fact invent this valve-gear geometry first.  What I was discussing was a very different point: that it isn't right to misspell 'that other guy's' name, or de Glehn's name, or Garratt's name, when referring to them.  In any case, nobody I know of in the States, either in the design/engineering community or in the operating world. called it Heusinger valve gear in the '30s or '40s or '50s ... which is the period we are discussing.  Thirty, end of statement.]

Sure, there are well-meaning people who can't get spelling or pronunciation worth a darn but who go ahead anyway.  We had a President of the United States who didn't know it wasn't 'nucular'.  Doesn't make it right, and doesn't make it somehow permissible either.  I'll tolerate it by letting it pass in technical discussion.  Some of Nigel Day's writing makes me want to eat nails when I come across it, but I stuff it in because the ideas and the engineering make it worthwhile.  But as you've mentioned -- this discussion hasn't turned properly technical enough yet (not for any fault on your part).  So let's get back to Juniatha's Triplexes.

Please point me to the updated version of the drawings, so I can see the better 'new' detail -- or just 'bump' the post that has the URL in it.

(BTW, that's 'Dylanious'  Trust me.)

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Posted by Juniatha on Monday, June 17, 2013 3:54 PM

Hi Overmod

The NORD locomotives couldn't have been more different from the NYC J classes .   Why should the NYC have observed the - not at all popular - w/a designation of two prototype engines long since vanished from the rails of 'Old Europe'?

What we see here is what has surprised me more than once : rail friends take such things a lot more strictly than did the railways that *used* these designations in daily business language for understanding each other .  In the event an engine depot manager should ask his workshop foreman "Now do you have that Hudson ready that came in last night with a hot xyz ?" the risk of the workshop foreman answering

"Well , depends - do you mean that NORD four cylinder compound with the duTemple firebox , or do you mean the little tank engine in stall 25 , or in fact should you mean one of our latest fast heavy mainline express engines with a double axle Delta truck ?"

was - tolarably  - nil .

Maybe we should think about it and not do as the Germans had done one ( not just one ) time in a forum when a guy posted some pictures of 03 class Pacifics and in a side remark happened to mention the engines at that late hour in their carriere didn't even carry the usual little depot plates at their cab sides .

Now , on that trifle side remark a storm broke loose about these little plate and inf they were on or but partly and if partly meant on part of the engines , that again meaning on one side only or on some of the engines only but on both sides then or if the depot was just written on and if this could be counted or not and so on and so on .   The steam staff at the depot just ran the engines and got trains handled - plate or not it didn't compromise performance by the smallest degree .

So , some of you may call my use of the term SE Mallet disrespectful ( which is not my intention ) or unwarranted ( which I think is not true ) or whatever : I just take my freedom to use it , lest one turns up with a document proving he had inherited the rights to that name by the descendants of Anatole Mallet himself . 

And BTW : why didn't those criticize my use of the term 'Triplex' ?  That invention of Hendersons also involved a compounding from center to outer engine units - and an exhaust to the rear , which definitely I wouldn't use . So my Triplex isn't Triplex as much as the SE Mallet isn't - now what ? - Mallet ( I didn't propose that )

Spelling : Oh , there are some very stout supporters of those *articulated* 'double ender Beyer-Peacock locos and they insist on calling them a 'Garrett' or even a 'Garret' (supposedly that's the narrow gauge version , i.e. narrower than Cape Gauge .  I must say , what about the 'Gerrytt' or the 'Jerrat' .  Well the 'Jerrat' really *is* a rat of a locomotive , so much is for sure ...

And please not again the Walschaert's theme !  Call their standard valve gear ( gear already *is* gear , Overmod ) a Walschaert's in Germany and they bear it down on you " Heusinger , Heusinger ! It's called Heusinger !  Heusinger Heusinger and Heusinger again for now and until the 12th of never !"

And yes there are those who would use names of engineers related to four cylinder compound engines in ways that are so ill-articulated it's mind bogling .

Never mind - don't think twice - it's alright , said Bob the Dilaneous

More to technical points , perhaps ?

Regards

Juniatha

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Posted by Paul Milenkovic on Monday, June 17, 2013 1:07 PM

I vote for reserving the word "Mallet" for compound expansion and calling the "other ones" simple articulated.

This isn't just rivet counting -- the true Mallet had very different characteristics with respect to speed and the kinds of trains they ran in relation to the simple articulateds.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?

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Posted by Overmod on Monday, June 17, 2013 12:09 PM

Juniatha

 ... Anatole Mallet's invention was on both articulating and compounding the two drive sets.  Now , one of the two has been dropped in the later development of the locomotives , retaining the other - why stop calling the articulation part of the idea after its inventor?

Because the inventor himself so strongly disparaged any association of his idea with non-compounding. Think of it being done out of courtesy, not disrespect.

Simply writing Articulated for SE locomotives having basically Mallet type of hinged frames does not say anything - an articulated could be any non-rigid frame locomotive.

We use 'simple articulated' as a technical term for "Mallet chassis with simple expansion" and it should be understood specifically as such.  All other forms of articulated locomotive will either not have short terms, or be known by their specific type (Garratt, Meyer, Klien-Lindner, etc.)

... the Southern Pacific cab-ahead types may *not* be considered Mallets , even if they [were to] have been compounds.   And rightly so , since the idea of turning around all of the locomotive when the only thing they wanted up front was the cab robbed the Mallet - indiscriminatingly of expansion mode - of it's major virtue in curve entering : the swinging front end section!  Now it was the rigid frame unit that hit the outer rail - *outch* !!! - and flanges of much fewer leading axles , now including a rigid frame 'first' coupled axle had to take up lateral thrust for turning moment *against* ( !! not by help of !! ) a counterwise swivelling *now trailing* hinged unit that now did nothing to turn the locomotive through curve - an inversion in the true sense of Anatole Mallet's idea!

I strongly disagree with most of this, for reasons I've covered in part via PM.  The argument about whether the locomotive is actually a 2-8-8-4 vs. a "4-8-8-2" for the purposes of Whyte coding has merit.  Thinking a Mallet chassis is destabilized because operating backward (given a proper 'leading' truck design, of course) is not really true, and I don't think the locomotive is at all disqualified from "Mallet-hood" merely for that reason.

The truck under the AC class firebox acts just like a normal pin-guided truck and steers the 'leading' flanges into curves more or less like any eight-coupled locomotive geometry.  There is a higher polar moment of inertia (from the overhanging boiler) but that in and of itself won't be destabilizing.  And in any case running the hinged engine with its pivot leading makes it far, far more dynamically stable than shoving it like a huge double-pendulum Bissel down the track...

Same with the von Borries type of four cylinder compound and the deGlehn - a little interpretation must be allowed for , or these terms as the locomotives designed by these mech E will disappear in history and we cannot use them anymore to describe variations of the basic four cylinder compound engine.

Help!  It's already happening to the de Glehn-du Bousquet locomotive design!  People are even forgetting how to spell Alfred's name!  Don't let him share Herb's fate! ...  ;-}

Seriously: is anyone going to confuse a von Borries balanced compound (with all four cylinders driving on one axle) with a de Glehn-du Bousquet design (where the drive is explicitly split, *but* there doesn't seem to be any distinction between LP inside and LP outside)?

Is there really any danger of losing the distinctions between any of the different flavors of four-cylinder compound as long as there are pedants like... well... like me... who try to keep them sharp?  Especially in a world where we can download Gairns' book on the subject, with all the details, for free...

But no, I don't think it is 'wrong' to use the term "SE Mallet" -- although I DO think it is wrong to call Walschaerts valve drive "Walschaert" or use any of the regrettably prolific misspellings of 'Garratt'.  Now that Mallet is no longer actively protesting .. at least as far as I am aware ... there is no good reason not to memorialize his idea of physical articulation, just as you have said.

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Posted by Overmod on Monday, June 17, 2013 10:35 AM

Firelock76

Hi Juniatha!  Good point on whether a 4-6-2 tank engine is a Pacific.  If a 4-6-4 configuration makes a "Hudson"  then the good old Jersey Central had a "Hudson"  before the New York Central did.  CNJ had a tank engine with that wheel arraingement in 1923, four years before the NYC got it.

Maybe a 4-6-4 should be called a "Hackensack", or a Passaic", or a "Raritan" type!

But that was already a decade after the REAL 4-6-4 type was invented (not coincidentally, for this thread, by du Bousquet of the Nord) -- and named.

And the REAL first modern American 4-6-4 class... the NYC Hudsons being 'first' only because of MILW poverty... were given just the same name, in recognition.

So tank or no tank... Baltic.

(We have subsequently developed a formal distinction of sorts between the names: if the rear truck is pin-guided it's classed as a Baltic, if Delta-style radial, it's classed as a Hudson.) 

Situation gets complicated, though: at least one English railroad called its 4-6-4Ts by the Baltic name... but then again, with 81" drivers they were scarcely in the normal tank-engine class.  (Did the streamlined German 61 001/002 tanks of the '30s get special type names?  We know the 2-4-2s of the LBE had a name...  ;-} )

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Posted by Overmod on Monday, June 17, 2013 9:46 AM

daveklepper
The New York Central had 4-6-4T's for the Boston and Albany suburban out of Souh Station. Boston.   From the front, they looked llike slightly reduced-size J-1 Hudsons.

4-6-6Ts, weren't they?

I have always assumed that the use of the "T" for tank engine discriminated a given nominal Whyte wheel arrangement from the 'tender-equipped' version that had the fancy name.

In a sense, the 4-6-6 is just like a 4-6-0 with half a six-wheel tender grafted onto the back end.  

It would be fun to come up with a list of names for the various tank wheel arrangements.  It's relatively easy to see why there was little desire to do so, in those long-before-Thomas days.  Not much romance in the mighty tank engine, or the service it provided!

(I can almost see an old "Railroad Magazine" article describing the high drama of a trip on a suburban run, complete with stormy weather, a threatened washout at a culvert averted by the canny pluck of the wise engineman, a pretty commuter waving her red underdrawers to stop the train... etc.  

Or perhaps not.  Perhaps better not.)

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Posted by daveklepper on Monday, June 17, 2013 8:33 AM

The New York Central had 4-6-4T's for the Boston and Albany suburban out of Souh Station. Boston.   From the ftront, they looked llike slightly reducedsize J-1 Hudsons.  They had rear headlghts and often did pull trains in reverse.  No one I knew called them Hudsons, however.   On the B&A, that term was reserved for the J-2's, the 600's.   They were simply called "tanks."   In 1949 they were still handling 90% of suburban service, including all the Riverside Loop trains, those going out on the main line (still in use) and returning on the Highland Branch, or the reverse.   The Highland Branch is now the D route of the Grreen Line Subway, operated by Breda and Japanese LRV's.

Some Pacifics handles main line express commuter runs to Framingham and Worcester.

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Posted by CSSHEGEWISCH on Monday, June 17, 2013 6:59 AM

The discussion over nomenclature can be variously amusing or interesting, we can use any word we want as long as we agree on the definition.

In a similar vein, Lionel Wiener, in "Articulated Locomotives", had to define rather precisely what was meant by an Engerth locomotive, as the term was used to describe a variety of designs.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by Firelock76 on Sunday, June 16, 2013 5:38 PM

Hi Juniatha!  Good point on whether a 4-6-2 tank engine is a Pacific.  If a 4-6-4 configuration makes a "Hudson"  then the good old Jersey Central had a "Hudson"  before the New York Central did.  CNJ had a tank engine with that wheel arraingement in 1923, four years before the NYC got it.

Maybe a 4-6-4 should be called a "Hackensack", or a Passaic", or a "Raritan" type!

Wayne

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Posted by Juniatha on Sunday, June 16, 2013 5:07 PM

Thanks , Feltonhill

and I will try to post my layouted version , too - it contains a couple of further information .

Kind regards

= J =

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Posted by Juniatha on Sunday, June 16, 2013 5:05 PM

Hi Dave

well Dave , I know that ;  Anatole Mallet's invention was on both articulating and compounding the two drive sets .

Now , one of the two has been dropped in the later development of the locomotives , retaining the other - why stop calling the articulation part of the idea after its inventor ?   There have been many compound locomotive types - nobody would call them all after Anatole Mallet , the deciding part in fact was the way he had broken the frames in two and hinged the *front one* so it could enter curve easier by swivelling .   It is this type of articulation in a locomotive , in contrast to Garratt , Union Garratt , Meyer or what have you ,  that is typical of a Mallet type locomotive - after all history has well proven that hinging two parts of a framework in this way does not depend on the way steam is being used . Simply writing Articulated for SE locomotives having basically Mallet type of hinged frames does not say anything - an articulated could be any non-rigid frame locomotive .

Of course a simple expansion Mallet was not an original Mallet type - yet so wasn't the later design of hinge , so wasn't superheating , so weren't trailing double or triple axle Delta trucks to support firebox and so on .

It's the *principle idea* of how to realise splitting frames under one boiler into a *front* swivelling section and a rigid *rear* section ,  that I consider essential in describing a Mallet type of engine .

In this way the Southern Pacific Cab Head types may *not* be considered Mallets , even if they would have been compounds .   And rightly so , since the idea of turning around all of the locomotive when the only thing they wanted up front was the cab robbed the Mallet - indiscriminatingly of expansion mode - of it's major virtue in curve entering : the swinging front end section !  Now it was the rigid frame unit that hit the outer rail - *outch* !!! - and flanges of much fewer leading axles , now including a rigid frame 'first' coupled axle had to take up lateral thrust for turning moment *against* ( !! not by help of !! ) a counterwise swivelling *now trailing* hinged unit that now did nothing to turn the locomotive through curve - an inversion in the true sense of Anatole Mallet's idea !

Same with the von Borries type of four cylinder compound and the deGlehn - a little interpretation must be allowed for , or these terms as the locomotives designed by these mech E will disappear in history and we cannot use them anymore to describe variations of the basic four cylinder compound engine .

Because its not an original Mallet I always write SE Mallet if so - you may call it my free interpretation , yet , then what about people who call a 4-6-2 tank engine a Pacific ?  Mind boggling if you ask me - but that's another story ...

Kind regards

= J =

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Posted by daveklepper on Sunday, June 16, 2013 1:38 PM

Juniatha, how, how, how, could you possibly use the term Mallet, to describe a simple articulated?  Coomon usage is mistake.  A Mallet is ONLY an articulated locomotive that uses its steam twice.  You know that!

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Posted by Firelock76 on Sunday, June 16, 2013 12:34 PM

Hi Juniatha!  You know, every time you come on the Forum you continue to amaze.  I learn something new with every engineering post of yours.

On the other hand, when I think of the steam 'might-have-beens"  I want to break down and cry!

Those lousy diesels!

Wayne

  • Member since
    December 2005
  • From: Cardiff, CA
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Posted by erikem on Saturday, June 15, 2013 11:24 PM

Juniatha,

Your effort is appreciated.

- Erik

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