Mallets VS Simple Articulated VS Duplex

[@paulleow8017]

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

[@gntlmn1956]

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

[@MrPatrickgannon]

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

[@namelessone3339]

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.

[@Scybren]

One on display in Duluth is on rollers to allow the wheels to be demonstrated, heard it was gettin work done on it tho.

[@hawkeyeten2450]

Ironically, UP's Big Boy 4014 IIRC ran on some of the very tracks that those giants once plodded when it visited Duluth in 2019.

[@collinparks274]

They also have a 7 1/4" guage live steam replica of the Yellowstone class now too, it was built by someone that passed away just before a relative donated it to the museum, unfortunately they done run it, but it there

[@maritaflores1061]

Yellowstone is a volcano that will go boom and potentially end the world

[@nssrrailfan]

I volunteer at the LSRM, and I see that thing every time I go.

[@Living_Life_RN]

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.

[@stuartaaron613]

The Gresley 4-6-2s, like the A-3 Flying Scotsman and the A-4 Mallard were three cylinder, and used the same valve gear system as the UP 9000. Alco had licensed the Gresley system.

[@Living_Life_RN]

@@stuartaaron613 Never realised Gresley licensed out his designs! I guess if it’s a good design then you might as well let others (except your competitors) use it. I think it was mainly locos like the LMS Princess Coronations that used the 4-cylinder plan.

[@stuartaaron613]

@@Living_Life_RN Oliver Bullied of the Southern Railway (UK) used a three cylinder design in his Merchant Navy, West Country, and Battle of Britain class 4-6-2s, but with a different valve gear system than used by Gresley.

[@paulleow8017]

@@Living_Life_RN i believe the New Haven 4-8-2s also had Gresley valve gear

[@scottb8175]

It isn't widely known in the western hemisphere, but the UK and continental European steam locomotives were pound for pound some of the world's most powerful, due to the number of cylinders, excellent running gear, valves, rods, boilers, etc... Upsize those locomotives to Big Boy weight and dimensions and you'd have a steam locomotive that could pull a Big Boy backward at 90 mph.

[@victorcontreras3368]

Thanks for the good information! I learned many points of the different terminology and will watch again to remember the facts 👍

[@owainlloyddavies7107]

shots fired at history in the dark😏

[@gamerfan8445]

To be fair he have it coming

[@guester_m0nacho]

:/

[@PeterFurst-b8w]

UP: build huge locomotives and keep at least one of them PRR: build duplexes and if they're not successful scrap'em

[@papamemesauce82]

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

[@railroadexplained5767]

I do believe it wasn't as prevalent on the s1 as much as on the t1

[@silverstonestudios01]

@@railroadexplained5767 That's actually a trait that was only a problem on the prototype and the earlier models. A big theory about the wheelslip on the T1 was that the crews just weren't experience in operating the locomotive's and it's sheer amount of power. You have to remember the engineers that were driving these had some from K4's and smaller locomotives, and as long as these things were in service, the drivers didn't have the time to master them.

[@railroadexplained5767]

@@silverstonestudios01 I forgot that

[@silverstonestudios01]

@@railroadexplained5767 at least you made a video on the subject, good on you man

[@jordanalexander615]

People also tend to look down in their tractive effort but at the end of the day they were built or speed. And still had decent tractive effort. They did have big drivers after all . Never built them for freight so wasn't really an issue.

[@isaacwatanabe9599]

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

[@tybehny5722]

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.👌

[@officialpennsyjoe]

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

[@stuartaaron613]

The AE front cylinders were 48" in diameter, the largest ever used on any steam locomotive.

[@west_side_9]

Yeah, those things were colossal

[@officialpennsyjoe]

@@stuartaaron613 The AE had one of the biggest boiler diameters too.

[@stuartaaron613]

@@officialpennsyjoe 118" diameter.

[@Train_Tok_Man]

Maybe the AE’s weighed bigger, but in terms of Tractive Effort, the N&W Y Classes were king. The Y6B’s for example were said to make 170,000 Lbs of Tractive Effort. Compared to the AE’s 115,000 Lbs, it’ll be left behind in a strength competition.

[@Kghammond852]

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.

[@SouRwy4501Productions]

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.

[@tacticalcalebgaming7264]

That’s pretty cool

[@scottb8175]

The Norfolk and Western Y6b and other compound articulateds used simpling valves for starting and slow speeds as well. The Y6b's starting tractive force is often listed as 156 000 to 178 000 lbs - depending on the source. Compare that to the Big Boy's 135 000 lbs maximum tractive force, and remember the Big Boy weighed about 300 000 lbs more than the Y6b. But also note the simpling valve can't be used at even moderate slow speeds. Generally anything over 8 mph - as doing so uses up the steam generation capacity of the boiler and then steam pressure drops off rapidly too, actually reducing the tractive effort to below that obtained when operating compound. Many large steam locomotives also used trailing truck booster engines, which had the same problem at above walking speeds and were only useful to assist starting tractive force.

[@collinparks274]

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

[@scottb8175]

As a fan of SP steam, and someone who has seen all three surviving DM&IR Yellowstones in person (at Duluth and Two Harbors) - I can't agree with that. They look closely related when viewed in photos, but are definitely not the same locomotive design reversed. The DM&IR Yellowstones are supersized monsters - side by side comparable in size and tractive effort to the UP Alco Big Boy - and both of those are much larger than the SP AC-11/12. The AC 11/12 is actually smaller than many 4-6-6-4 Challengers. I have HO scale drawings of all the locomotives I mention here, and some brass models of both AC11/12's and NP Z-8 Challengers, and the Z-8 Challenger is considerably bigger than the AC. And the M-3/4 DM&IR are larger than the Z-8. Even bigger than the Z-8, and comparable and almost equal to the M-3/4 is the NP Z-5, of which I once had a brass model. The AC 11/12 are more like a slightly smaller and reversed version of the Western Pacific's last version of 2-8-8-2's, also from Baldwin. For a more direct comparative SP locomotive to the DM&IR M-3/4 - look at the SP AC-9 from Lima.

[@russellgxy2905]

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

[@csxriverlinecatches4736]

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

[@mikeharazim9272]

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.

[@Shane_Geiger]

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

[@jordanalexander615]

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

[@jordanalexander615]

I realized they actually had both. They ended up converting a couple mallets into simple articulated for mostly helper service in the mountains

[@Lucius_Chiaraviglio]

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.

[@themanformerlyknownascomme777]

from what I read, the problem was that there was no way to keep the drivers in sync and that's what caused consent wheel slip.

[@elijahgreenberg2634]

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.

[@blackbirdgaming8147]

Pretty much all compounds (especially mallets) have simpling valves for starting. You’d have to run them in simple mode to start, because from a dead stop, a compound has little to no steam being exhausted to the low pressure cylinders. Once a certain speed was reached, the locomotive would switch over/could be switched over to compound. So technically yes, you’re correct. That’s why if you watch C&O 1309 start on a hill and you listen closely, you will hear the exhaust change. It will sound like a simple articulated, and then suddenly the exhaust will become a bit “mushier”, as well as the number of exhaust beats changing as the engine has now switched over to compound mode.

[@BotLiquor]

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.

[@scottb8175]

The all-time most piston driven drivers champs - Erie and Virginian Triplex locomotives (2-8-8-8-2 and 2-8-8-8-4) - also used the engine under the tender design concept - but were unsuccessful in operation.

[@agostinodibella9939]

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

[@stuartaaron613]

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

[@jeffreycie3075]

Enjoyable history. Thank You!

[@victorcontreras9138]

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

[@johnoneill5661]

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

[@NorthernOhioRailroadAction]

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

[@kathyhenderson824]

you deserve more subscribers!

[@metalgear6531]

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

[@owenjones9659]

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

[@railroadexplained5767]

I'll put it on the list and see what I can do

[@acersalman8258]

Beautiful trains you made things wonderful good useful beautiful make human life happy you science education original God bless you and protect you ❤

[@YourLocalHistorian]

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

[@jamescerone]

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

[@mesenteria]

The other way around. You want more power, you go simple....same high pressure in both sets of cylinders. That gets you over the grade, and allows for heavier lifting when starting from a stop. When you don't need the power, and also want more efficient use of the thermal energy in the steam, you route the expanded steam from the smaller cylinders into the larger cylinders and use that heat energy to move the piston in the larger cylinders.

[@pontushaggstrom6261]

Thank you

[@tonyclough9844]

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

[@Mark-xv5lb]

thanks--very clear

[@collinblack_60103-]

Very informative.

[@roelantverhoeven371]

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

[@steeljawX]

Ehhhh, I'd say that information with a boulder of rock salt and the quote from Dr. Ian Malcolm from Jurassic Park about being concerned if they could rather than focusing on whether or not they should in my back pocket. And I'm saying that staring straight at the most infamous mallet in US history west of the Mississippi, the Uintah Railway Mallet. Could it be used on that janky rail line? Yes. Should it have been used on that janky rail line? No. Did they use it on that janky rail line? To everyone's misfortune and wonder.

[@aldenconsolver3428]

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.

[@theidkwhatsgoingonchannel3840]

Forgot the Simple Articulate Skookum :(

[@Trainmaster437]

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

[@scottb8175]

The original Yellowstones where the NP Z-5's, the largest locomotive built until the Big Boy and Alleghany. They got the name because they were specifically designed to handle trains over the Mandan North Dakota - Glendive Montana Yellowstone Division on the Northern Pacific without the need for double heading locomotives on regular freights over the division's problematic saw tooth profile, with many long , steep grades....in bad alkali water territory, burning poor quality Rosebud coal...regarded as the worst operating conditions for steam locomotives on the NP system.

[@robertbalazslorincz8218]

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

[@cegicreator2476]

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

[@scottb8175]

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

[@zachllerindustries3801]

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.

[@osagejon8972]

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.

[@railroadexplained5767]

They can run on both?

[@sharkheadism]

They're considered compounds, but they would use simple mode for starting.

[@theimaginationstation1899]

All componds had the ability to start by using boiler steam in the LP cylinders - otherwise, at start, they'd be robbed of a significant part of their tractive effort.

[@machinist1879]

In development of the last run of Y6b’s, N&W mechanical engineers developed a “booster valve” which gave the engineer the discretion to inject a “boost” of fresh boiler steam into the feed pipe to secondary/front set of cylinders. This boost was to be employed during demand for high tractive effort. It brought peak horsepower up to 5,600. As shoppings occurred the feature was retrofitted to all the Y6’s. Quite incredible, considering it had a 4-8-4 size boiler.

[@danielargabright5591]

@@machinist1879 i saw a video by a guy who made movies of the last days of steam on the N&W . he got good footage as well explained that when the train got below 10 mph going uphill they would switch to simple mode to give them the boost they needed to get over the hill. i think this allowed the N&W to use less locomotives and crew thus reducing overall operating costs. his name was ed or eddy i think.

[@normanrickleyjr7178]

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.

[@thomasdeturk5142]

I’ll restore the big boy 4020.

[@SirLANsalot]

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.

[@Alcochaser]

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.

[@rescue270]

His name was actually pronounced. more like "Mayyey" and that pronunciation is what should used be used when describing his innovation. Just like a clarinet can have Boehm ("Bame") or Albert ("Allbear") key systems.

[@wnh7790]

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

[@DirtyDan490-t2v]

What about Compound articulated?

[@railroadexplained5767]

That is something that I admit I completely forgot about when making this video.

[@michaeltb1358]

What about the Garrets? Fully articulated for sharper curves.

[@railroadexplained5767]

I was focused on US steamers. The garrets deserve their own video, but I didn't have them in mind at the time, since no US railroad used them as far as I know

[@jnbsp3512]

oh no I fell into the f1nn5ter to railroads pipeline

[@railroadexplained5767]

lol

[@TheWeavingBagel]

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

[@railroadexplained5767]

From what it seems at least for the prr, the s1 had more than half the weight not on the driving wheels. For the t1, it was more the engineers not used to it. The C&O tested a t1 and they didn't have issues.

[@scottb8175]

Its all in a number referred to by the steam locomotive designers as the Factor of Adhesion - essentially a ratio of the weight on the driver wheels vs. the locomotive's mechanical theoretical tractive effort (calculated from the boiler steam pressure, piston size, maximum valve cut off %, piston stroke, and wheel diameter). Steam locomotives generally started having chronic wheel slip issues when the FoA was above 3.75. The PRR Duplexes were all above 4.0, I believe. Some articulateds would have problems with only the front hinged set of drivers having a higher FoA than the rear set and thus being prone to slipping,, while others would be fine until they started to slip, but were then hard to stop slipping without closing the throttle immediately, causing all kinds of problems for the locomotive and crews.

[@Bigboy4014-x6s]

1:39 what kind of challenger is that

[@railroadexplained5767]

Rio Grande Challenger

[@Bigboy4014-x6s]

@railroadexplained5767 it looks like a steam and a diesel combined

[@wnh7790]

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

[@funtechxtream8753]

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

[@hafidzashidiq2579]

DD 51

[@pacificcoastpiper3949]

It’s Duluth MESABI and iron range

[@namelessone3339]

I'd suggest that you do you research.

[@pacificcoastpiper3949]

@@namelessone3339 I’m correct as far as the Great Lakes freighters are concerned. S.S Mesabi Miner

[@BigP890]

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.

[@concept5631]

0:28

[@VonVitto]

Sir watch your mouth

[@railroadexplained5767]

No