Types of Steam Locomotives

[joesap1]

After reading TRAINS and CLASSIC TRAINS for quite a while I am still perplexed as to the classification of steam locomotives. Could someone please define in layman terms what distinguishes each of the following locomotives:

Articulated -

Mallet -

Berkshire -

There are other steam locomotives, for sure, but these three classes are almost always mentioned. Your help in this matter will not go unappreciated.
Thank you.

[IRONROOSTER]

Here's a link http://www.spikesys.com/Trains/articuld.html explaining Mallets and articulated's.
Same site different page describes the Whyte classification system for steam locomotives http://www.spikesys.com/Trains/wyte_sys.html
The Berkshire is a 2-8-4 wheel arrangement.
Enjoy
Paul

[CSSHEGEWISCH]

Not a bad link but Wiener also classified Shays and Heislers as articulated locomotives, although I will concede that Garratts, Fairlies, Mallets (both simple and compound) and Meyers will cover the majority of articulated and semi-articulated steam locomotives built.

[Anonymous]

By the way, what is the type name for 2-6-6-2, 2-6-6-4 and 0-10-2 wheel arrangements??

[joesap1]

I guess I am just ignorant when it comes to steam. I went to those two links provided and while the information was interesting, it did NOT answer my question.

I was looking for a clear and concise definition of these locomotive types. The site given in these links assumed you knew what a mallet or articulated was. Their very brief explanations was hardly satisfactory.

Could you please be of more assistance. Thank you.

[palallin]

An articulated locomotive is equipped with two (or more) sets of driving wheels and their cylnders, at least one of the sets able to pivot with respect to the frame of the locomotive allowing it to negotiate sharper curves tahn if both sets of drivers were rigid. Each of the driver/cylinder sets is called an "engine," BTW.

A Mallet is a subtype of articulated using a compound steam supply. What that means is that the steam is used twice. It is fed first into the high-pressure cylinders of the rear engine (most common arrangement) and then exhausted into the low-pressure cylinders (identifiable by being much larger in diameter) of the forward engine. Simple articulateds use the steam only once, and both their engines use high-pressure cylinders. Examples of Simple articulateds include the famous UP Big Boys (4-8-8-4) and Challengers (4-6-6-4); an example of the Mallet Articulated is the N&W Y-6 class (2-8-8-2). It should be noted that, among the articulated locomotives, you will find less standardization of type names, and the Whyte System deals poorly with them.

[CSSHEGEWISCH]

Lionel Wiener is a little more concise with his definitions:
An articulated locomotive is one in which the frames holding the driving wheels are able to pivot with respect to the frame of the locomotive. Examples would be Garratts, Shays and Heislers.

A semi-articulated locomotive is one in which one frame holding the driving wheels is able to pivot with respect to the frame of the locomotive while the other is rigidly attached to the frame of the locomotive. Prime example would be a Mallet.

Wiener classified locomotives with trailing truck boosters as temporarily articulated.

[AltonFan]

QUOTE: Originally posted by DeLuxe

By the way, what is the type name for 2-6-6-2, 2-6-6-4 and 0-10-2 wheel arrangements??

There were, AFAIK, no standard names associated with most articulated locomotives. IIRC, the Southern Pacific called 2-6-6-2 and 2-6-6-4 types "Articulated Prairies".

The 0-10-2 was an extremely rare wheel arrangement. The only engines commerically built with this arrangement were built for the Union Railroad, and one often finds the arrangement called "Union Switcher".

OTOH, the C&NW had a pair of Santa Fe types (2-10-2) from which the pilot trucks had been removed. These were used on the hump at the Proviso yard, and had their pilot trucks removed because they tended to derail on the hump.

[joesap1]

Thanks for the clarification. There is still a bit of confusion since one lists a Mallet as a compound steam engine. While another says a Mallet only has one set of its drive wheels that pivot. Probably both definitions are true, depending on the particular locomotive.
Is this a correct assumption?

[Anonymous]

I also heard that the DM&IR was using 0-10-2´s on their ore trains....

[CSSHEGEWISCH]

QUOTE: Originally posted by DeLuxe

I also heard that the DM&IR was using 0-10-2´s on their ore trains....

These may well have been the former Union RR 0-10-2's. As was true in the diesel era, the various US Steel roads were known to swap power among themselves, especially late in the steam era when much of the steam wound up on DM&IR.

[DanRaitz]

Yes, The DM&IR did have 9 former Union RR 0-10-2's. Missabe #601 - #609, ex Union #301 - #309. Missabe picked these locos up in 1949. As a side note Missabe #603 (Union #303) was returned to the Union RR for display in 1961, and I have heard that she displays Union RR markings on one side and DM&IR markings on the other side. Can anyone confrim this?

Dan

[Anonymous]

Joe,
The French locomotive designer Mallet, French pronunciation approximately MAL-LAY with equal emphasis on both syllables, created the first articulated locomotive that had the rear engine fixed beneath the boiler with high pressure cylinders and had the front engine hinged to get around sharp curves with low pressure (larger in diameter than the high pressure ones) cylinders using the steam exhausted from the rear engine. Early designs had the rear engine equipped with piston valves and the front with slide valves

The English pronounced his name roughly MAL-ley, the first syllable accented and rhyming with Salley.

The extra piping and plumbing needed to connect the rear engine to the front caused maintenance grief and many were converted from compound to simple articulateds with both engines receiving high pressure steam.

Mr. Vaulclain was a proponent of compound steam and used the principle on non-articulated engines; those with piston valves had a bulky looking triple cylinder set - valves, high pressure pistons, and low pressure pistons. Maintenance problems often resulted in these engines being converted to simple.

Art

[joesap1]

Thanks for all the information. I believe I now know something about the types of steam locomotives, but,please, don't test me.

[AltonFan]

One will notice that steam locomotive compounding experiments largely disappeared with the development of the superheater. The original point of compunds was to get more thermal efficiency from a steam engine. The superheater did a better job of this than compound arrangements.

However, compounding was was revived to reduce the weight of running gear. 4-10-2s and the 4-12-2 were all three-cylinder compounds with high pressure cylinders on the outside, and a high pressue cylinder cast into the locomotive frame. The center cylinder drove a rod connected to a crank on the main axle.

The N&W liked the mallet, and all their articulated engines were mallets.

[selector]

QUOTE: Originally posted by joesap1

Thanks for the clarification. There is still a bit of confusion since one lists a Mallet as a compound steam engine. While another says a Mallet only has one set of its drive wheels that pivot. Probably both definitions are true, depending on the particular locomotive.
Is this a correct assumption?

That is correct. Mallets, unaltered, are by definition "compound" locomotives with two engines under the boiler. The engine closest to the cab was rigidly fixed to the frame and could not pivot relative to the boiler. The front engine, the one using steam scavenged from the rear high-pressure engine, could pivot, and its cylinders got the most out of the lower pressure (second hand) steam by exposing it to considerably larger surface areas on the associated pistons...a characteristic evinced by the noticeably larger cylinders.

Locomotives that had their engines elsewhere, i.e., not under the boiler, include the famous Beyer-Garratt locomotives. I believe that they were "simple" locomotives, if a bit odd, in that they sent high pressure steam directly to both engines. I saw one in use in the Andes Mountains of Peru in the early 1960's...quite impressive.

[Anonymous]

Crandell,

Like this you mean? Double headed Garrat between Sydney and Newcastle NSW Australia. In service until 1973.





Thems was the days.[:p]

[Anonymous]

QUOTE: Originally posted by AltonFan


However, compounding was was revived to reduce the weight of running gear. 4-10-2s and the 4-12-2 were all three-cylinder compounds with high pressure cylinders on the outside, and a high pressue cylinder cast into the locomotive frame. The center cylinder drove a rod connected to a crank on the main axle.

As all 3 cylinders received high pressure steam, these locos were not compounds. The earlier Vaulclain compunds had high pressure cylinders inside the frame which exhausted into low pressure cylinders outside the frame. The inside cylinder on 4-10-2's and 4-12-2's did have slightly smaller dimensions than the outer 2 and the exhaust was siameased with the exhaust from an outer cylinder, but the steam was not being used twice.

Triple expansion steam engines were very common in steam ships and Titanic had 2 triple expansion steam engines which exhausted into a steam turbine, so it used steam 4 times.

[CSSHEGEWISCH]

As is relatively well-known, there was only one triple-expansion steam locomotive in the United States: D&H 1403, which was a 4-8-0. Steam came from the boiler to a high-pressure cylinder under the engineer's side of the cab, then exhausted to an intermediate-pressure cylinder under the fireman's side, which then exhausted to a pair of low-pressure cylinder cylinders at the front in the usual location, which in turn exhausted up the stack. As can be imagined, it was incredibly efficient in its use of steam but was a maintenance nightmare.

The 60-series Garratts in New South Wales were the only 4-8-4+4-8-4 Garratts and were the largest Garratts ever built.

[selector]

QUOTE: Originally posted by bush9245

Crandell,

Like this you mean? Double headed Garrat between Sydney and Newcastle NSW Australia. In service until 1973.





Thems was the days.[:p]

They certainly was! [:D] Yes, that is what I was talking about. I think the Federal Railway of Peru had two of them, and I cannot recall if they were 2-6-0-0-6-2, 4-6-0-0-6-4, or whatever. I recall that the engines were under tenders at opposite ends of the boiler, and that the whole valley thundered when one of them went by. ( I was about 10 at the time....a few leaves have passed under the bridge).

[jimrice4449]

All the N&W articulateds weren't compounds. The A class was simple.

[daveklepper]

Excuse me, NOT all N&W articulated were Mallets. If I remember correctly, the Y's were all Mallets, all the 2-8-8-2's, (and the earlier 2-8-8-0's) but all the A's were simple expansion, the 2-6-6-4's. I hope an N&W expert will verify this.

[Anonymous]

Well since no one tackled the Berkshire end of it let me see if i can help here. These were for the most part remarkable machines. Ofcourse, to simply begin, Berkshire is the "Whyte Classification Name" for a steam locomotive having a 2-8-4 wheel arrangement. But Whyte didnt coin this name, OH NO no no. Ya see, legend has it that one day this guy named Woodard put this idea he called "Superpower" down on a set of rails. And this railroad said take your locomotive and pull our train over this mountain range faster, stronger, and more efficiently than before. Them mountains used to be called the Berkshires. After that day they would be called "conquered"! So Woodards 2-8-4 took the name of the mountain range and never gave it back. Now some other folks heard of this tale and thought HAH! what nonsense! So they bought 70 of them just to be sure. Thusly was born the "Million Dollar Fast Freights" of the NKP. OK fine the people thought. They have speed, but them NKP and PM folks just dont know how to hook them up! Well low and behold them suckers sure can pull coal too! We'll take 90 of them. Now this is a great and true story even if it is the very short version. Mr. Woodard worked for Lima. Had a great idea to make the one thing that was lacking in modern ( then) steamers. um... "power at speed". and we know that the "Superpower" or " Van Sweringen" berkshires as they were sometimes called, actually scaled down C&O Texas Types (2-10-4). Other versions of Berkshires were made aswell but make up the smallest amount of the total. All were very nice looking and in most cases very distinct from road to road. I speak of outward appearance only as for instance the PM, C&O, and NKP were virtually interchangeable. C&O and NKP having the most well known faces while PM and RF&P were very standard. L&N Big Emma's, unique? yes? The Berkshire story is a very in depth one and one can recant many facts and tales of these fine engines. And at the heart of most of these was Woodards theory in practice that he had made a boiler that could produce enough steam to give the man in the hotseat all the power he needed, even when the throttle was over his shoulder. Alot of these machines came with modern appliances, so more efficiency was also a reward. They were fast, rumors of 80mph for the 70" drivered versions are too common to not be true. Hundred car trains behind these spitfires were counted many times. And yes some even pulled passenger trains. A C&O K4 (Kanawha) here and there were known to have been photographed. If you want a locomotive with a good rich history, study this type. It certainly did earn its place in history as other locomotives did. Its the underdog that did!

Sincerely,

Power at Speed