Thank you so much for making this! I hear people call simple articulateds "mallets" way too much when they aren't. People tend to think that Mallet means the layout of the frames, but they forget that the patent for the design specified a compound cylinder set up

Yellowstone locomotives were also used by the Duluth, Missabe and Iron Range Railway for hauling iron ore from the mines to Lake Superior for transfer onto ore freighters. Three remain, though none are operable.

In the UK, we have quite a few fixed-frame 4 cylinder express passenger locomotives. These work like the UP 9000 series, but with 2 outside + 2 inside cylinders, rather than just the one inside cylinder.

Using the correct terminology can make or break a conversation and avoid confusion. Thank You for clearing this up.

Very well done and laughed my ass off when you explained standard locomotive can't handle sharp curves "to save their sorry ass." LOL

Fyi, the issue with the PRR S1 was that only 45% of the weight was on the drivers, which in theory should have caused the wheel slip issue But crews never actually complained about it, which implies that either the issue was fixed or it was never an issue

shots fired at history in the dark😏

Thanks for making this video. I'm a long time rail fan and I was aware of all these configurations, but I didn't know they had names. Very nice.👌

The Virginian AE had huge cylinders also. Possibly bigger than N&W's Y series.

The 2-8-8-4 yellow stones where used on the Duluth Missabe and Iron range to haul iron ore from the mines in Northern minnesota to the docks at Two harbors and duluth owned by United States steel they where one of the most powerful steam locomotives in the world second only to the N&W Y6Bs i believe. They can out pull a big boy in low speed service but in high speeds the big boy will take the win

The UK had divided drive locomotives (like duplex, but with inside and outside cylinders on the 2 drives, using compounding) in the late 1800s. By all accounts I have read, they were terrible; although they were too short to have problems with curves, they certainly had wheelslip, including at least 1 double expansion 3 cylinder type that had a tendency to get its low pressure into the wrong position so that it would start making its wheels slip in the opposite direction to the wheels driven by the high pressure cylinders.

Western Maryland Scenic Railroad 2-6-6-2 Mallet Steam Engine #1309 aka the Maryland Thunder is my BIG time favorite American articulated icon. As it is an operational articulated steamer, it runs on coal, wears the WM Fireball livery and promotes regular excursions in Cumberland, Maryland.

Fun fact: did you know that S.P.'s cab forward AC-12 class is the same engine as DM&IR's Yellowstone class, both are built by Baldwin and have the same wheel arrangement if you look at it from smoke box to cab

If you havent seen the Allegheny locomotive at the Henry Ford Museum in Dearborn Michigan, i siggest you do. You can climb inside and its really cool

If I remember correctly, and I may be wrong, but I'm pretty sure the C&O H6s (or at least WMSR #1309) could operate either as Mallets, for better efficiency, or Simple Articulateds for greater tractive effort.

Thanks so much for this information. Now I know these terms and what they stand for. Very good!

Rio grande also had 2-8-8-2 simple articulateds. They were pretty good locomotives. Lots of mountain use.

2-8-8-4 Yellowstone types were used by the Northern Pacific, Duluth, Missabe & Iron Range, Southern Pacific, and Baltimore & Ohio.

Excellent video really enjoyed it keep up the great work thanks again and have a wonderful day

Enjoyable history. Thank You!

It’s hard to imagine all the maintenance that those locomotives need to keep in operation!

To be fair to the Pennsylvania duplex most of their wheel slipping was proven to be from their engineers opening the steam valves too much due to muscle memory.

C&O 1309 has an interesting feature on it where it can switch between using a compound steaming arrangement and a simple articulated steaming arrangement. When it’s starting up or arriving at a station, the engineer uses the compound mode. However, when it’s moving along at higher speeds, the engineer can switch over to simple-articulated mode for easier steaming.

Can't wait for the T1 to be finished being made by the T1trust

FYI the Y6 locos could actually switch between simple and compound modes. IIRC they would use compound over grades and simple over flats

You had some really good looking monster steam engines back in the day 👍

Very informative.

thanks--very clear

could you do a video explaining and retracing the full western maryland cumberland branchline and where all the former track was that was torn up goes to because it would be cool to have a map of that

Believe it or not, Britain had a few Duplex locomotives in the Victorian era. Essentially they wanted locomotives with more traction than a standard single, but still with less friction than the 4-4-0's of the time would give. Their layout was odd though. The American duplexes are basically the same as a "simple" articulated but without articulation (The T1, S1, and Q2 were basically rigid "simple Mallets" while the Q1 and N-1 were rigid Meyers). British Duplexes, split the cylinders between inside and outside motion. The inside cylinders, like most Singles of the era, drove one pair of driving wheels, but another pair of outside cylinders would drive the outer pair. This divided drive setup, would later be used on some of Britain's most iconic express engines like the Stars, Castles, Duchesses, and even the Thompson and Peppercorn Pacifics. The only difference between them and he duplexes is that all the driving wheels were actually coupled together

you deserve more subscribers!

I believe yellow stones, or just a wheel arrangement rather than a type of simple articulated Locomotive

You want to see weird - different? Check out the cylinder arrangement of Canadian Pacific's R class 0-6-6-0's.

The B&O likely solved wheelslip by using coal dust to limit the flow of steam into the rear cylinders xd

there is something I would like to see your Source for the duplex, from my understanding simple articulated and the duplex where capable of the same speed, with that being said I have not read to much on the duplex design and haven't seen anything other the special passenger locomotive and cargo passenger locomotive using the design but I don't know why. One other thing for your Mallets vs Simple Articulated, mallets where used early on because of the limitations in boiler design which prevented them from producing boilers that could with stand higher steam pressures, improvements to boilers and the introduction of superheaters made simple articulated into a reality.

OK I didn't know that mallets are specifically compound engines but even *I* know that the big boy clearly is not a duplex

The yellowstones were used for the Duluth Mesabi & iron range.

Hey at least 5550 is gonna be the existent duplex back to 1

well now, I think you showed a quick pic of a simple articulated but did not go into the variations in the linkage, can not say I understand that any better than I did. The Mallets thing is just a variation on the early steamship duplex cylinders, which is of course more effective than a single-stage (before turbines most ships were done with triple expansion engines which were even more efficient. Now while we are wandering along with these engineering questions (which I love) why did steam trains not use a condenser? Saves water and allows the water to be kept at a higher temperature making it easier to reheat. VTE (vertical triple expansion) engines were relatively efficient and eventually became rather compact). Now we could get into the Uniflow configuration which was used on a lot of steam-powered non-turbine ships (including warships) in the second world war.

The large clyinders on mallets are compound engines and thats the low pressure one. Mallets with clyinders the same size are simple steam engines.

Thank you

Forgot the Simple Articulate Skookum :(

mallets were very popular on narrow gauge, some as small as 600 mm gauge!

Why does Challenger look like someone forgot to install Counter Strike Source in that Cheyenne footage?

The tough question to look at would be how a N and W Y6 would be classified... part time mallet when working compound and not a mallet when working simple? I'm not aware of any technical term that makes the distinction.

A mallet and articulated are one in the same. You mean simple articulated and compound articulates, yes? Simple articulated has high pressure steam going to all 4 cylinder. As opposed to compound articulated which the high pressure steam goes to one set of high pressure cylinders (usually the rear) and then is piped to the front (low pressure) cylinders. You can tell the simple from compound articulated locomotives by the front cylinders. The low pressure front cylinders are usually about twice the size of the rear high pressure cylinders. A good example of the simple articulated is the Big Boy, the newer Challenger, the Barrer-Garratts. Look at their drive cylinders. The compond articulated would be the N & W, A and Y class and even some of the older original UP Challengers were compound articulated, that I can think of right off my head. A mallet type locomotive is any class locomotive that has hinged or pivoting drive assemblies. Whether it be front middle or rear. More often the rear or middle drive is hard mounted to the locomotive main chassis. If I remember in my steam classes the triplex locomotives never worked for a multipled of reasons. The over length of the locomotive with tender, and more often, the boiler technology then never was able to make a boiler big enough or develop enough steam pressure to drive 6 drive cylinders properly. While the idea is always more drive wheels = more tractive effort, the triplexs never quite made the top of the list. Even though many were mammoth locomotives. The Baldwin Virginian XA 2-8-8-8-4 and the Baldwin/Erie P1 2-8-8-8-4 were probably the more noted successful triplexs. Much like the Quadduplex Super Garratt 2-6-6-2 + 2-6-6-2. But the Super Garratt was never made. The Barrer-Garratt/Barrer-Peacock class AO 4-8-8-4 + 4-8-8-4 would be a close friend to the super Garratt and even closer to The Big Boy and Challengers. Even though the Garratt's, both front and rear drive assemblies are hinged to the main boiler frame they are still considered mallets.

What about the Garrets? Fully articulated for sharper curves.

oh no I fell into the f1nn5ter to railroads pipeline

The duplex look what it's not that big for just a combination of open articulated frame and spring

I made a video about 844 on the front of every video on the channel

I am still wondering how simple articulated engines don't experience the same traction issues as duplex drives.

Duplex wasn't entirely that successful of a design. You were still basically a 4-8-4 but with extra cylinders. While this did increase total horsepower output by having more cylinders, it did not increase tractive effort causing a lot of wheel slip. Basically you got more power but not more traction and thus would slip more often, however you would get higher top speeds due to the extra HP generated. The Simple Articulated locomotives were the better setup out of the two articulated types, since they had better overall horsepower and traction and speed. Mallet's were very slow comparatively, but for what they were built for they didn't need the speed as most of the routes they were used on were short as well. Since most Mallets were used on the east coast where long range wasn't needed, with ATSF being the oddball out. The Challenger locomotive was also used by Northern Pacific, Spokane Portland and Seattle (was on the same build order as NP's), Denver and Rio Grand, and the Clinchfield besides Union Pacific being the original designers/requesters for such a locomotive. ALCO marketed it to other railroads with only the ones listed being interested in them. By the time the Big Boy rolled around, Dieselization was already underway and no other railroads were interested in him.

I don't care if it is named after a french guy, those engines are called MALLETS, (like the hammer).. There also three cylinder locomotives other then the 9000s.

It’s Duluth MESABI and iron range

DD 51

Ok just for future reference, with the duplexes, the Q2’s were by far the best being actually the most powerful steam locomotives ever made and fixing many problems that came from other generations of duplexes as the Q2’s were the final line of duplexes. The single S1 was an absolute pig and was too heavy and big for its own good. The T1’s were ok but did suffer a lot from wheel slip and did basically any duplex would because of the rigid frame. The Q1 was an utter disaster as the use of what was essentially a reversed cylinder shortened the firebox and also exposed the rear cylinders to a lot of heat, making running the engine very risky. Now touching back on the T1 duplexes, they weren’t amazing engines but the original 2 prototypes were actually pretty ok. No. 6110 and 6111 were much better made that the 5500 series of duplexes. They weren’t as prone to wheel slip but still were and many issues with their finicky driving and valve gear weren’t as prominent like they were in the later 5500 series of Duplexes used by the PRR. As for the B&O N1’s I know little to nothing about those but seeing the reversed cylinder design for the rear cylinders, I would assume that they would have suffered similar issues to the Q1 duplex if they did even cause trouble. Someone who actually gave some good insight on the PRR Duplexes was Jim van set Kolk and Christopher Kovacs.They both have pretty neat channels about trains and goes over engines in pretty good detail and give very good info on the engines that they have covered.

Sir watch your mouth

There is one more unique type of American Mallet (even if the term mallet doesn’t apply). This type of locomotive is called a Tractor locomotive with another locomotive wheel set beneath the tender. For example, one kind of tractor type used by the southern ry was a 2-8-2 w/ 2-6-2 wheels beneath the tender.