A bit thing you are missing here is while they ended up being pusher (banking) engines, that's not what they were intended for. (I manly learned about the Virginian 700, but I believe the Erie 3 where of the same reasoning) These were designed for Coal Drags, which don't need much in terms of speed, but did tend to need more than single digit top speeds. The want was for one big engine (and thus one crew) for these and to pull ever larger drags. But when they couldn't provide enough steam for the journey they were dropped down to pusher service. However in the US pusher service wasn't really anything special, a standard engine or two was typically enough for this and the benefits of a special engine for this was greatly outweighed by the costs.

Imagine being stuck at a railroad crossing and having to wait for a 6.7-mile-long train that's only going 4 mph...

I saw the thumbnail and thought "tank engine? That has a tender!" But nope it's just massive

Everyone knows and love the fictional mad scientist trope, but we've been glossing over how terrifying mad engineers are

Oh , for those good old days when they just went ahead and Built one to see if it would work or not .

I just love how ridiculous trains could get back in the day

One other issue the Triplex had was that, as it used its coal and water, the driving wheels under the "bunker" would lose traction and slip often because the weight of the coal and water pushing down on those particular driving wheels would drastically reduced the long the locomotive ran

0:17 "Each bogie was powered with three cylinders giving the Big Boys a significant amount of power" - No, and no! The Big Boys had one fixed engine unit (set of driving wheels) at the rear, and one swivelling engine unit at the front, which you could call a 'bogie' at a stretch. That was the '-8-8-' bit. The actual bogies (aka trucks) would have been the carrying wheels at each end, hence 4-8-8-4. And the engine units were twin cylinders, hence 4 in total. 0:40 "These boasted three cylinders per bogie" - again, no. So far as I'm aware, the Triplexes only had two cylinders per engine unit, also. This is why the UP 9000 4-12-2's - which did indeed have three cylinders - were such a notable exception in large US steam locomotive practice.

The Big Boy only had four cylinders-two on each engine set. Also, only the front set articulated; the rear set was rigid with the boiler and cab. Though, the Union Pacific did build a series of 4-12-2 locomotives that had three cylinders. One of them, #9000, survives today.

There is a (claimed) story that when a Triplex pulls a heavy train, possibly heavy freight, the locomotive pulled so strong, the couplings of the cars and trucks of the time could not withstand the power and, possibly, broke under pressure. That’s why they were used afterwards to push not to pull. Interesting story.

Another problem with the triplexes I'm surprised you didn't mention: As the fuel reserves were depleted the driving wheels under the "tender" became much more prone to slipping, so power would have to be reduced to all the drivers as the tender set did not have their own throttle valve.

A couple of things that you missed: *Too Much Power* - The Erie was the first to have Triplexes built. Named "Matt H. Shay" in honor of a beloved employee of the railroad, it was originally intended to pull trains up the steep grades on its own. During testing, it was pulling a train of 250 cars up an incline. The journey went well, until they hit the 17 mile mark; here, a coupling snapped, and the train was ground to a halt. Investigation found that the engine was so powerful that the shock of just normal operations was enough to literally tear apart rolling stock. Undeterred, they decided to instead have it serve as a banker. *Virginian Woes* - While the success of the Erie's triplexes is generally considered uneconomical at the best of times, the Virginia Railroad's sole example was far less successful. The XA (numbered 700) was designed to drag up to 10 miles an hour, but it was found that anything beyond ~5 mph would empty the boiler of steam faster than it could be produced. Despite actual personnel from Baldwin stationed where the engine was kept to try and assist in hammering out the problems, it just simply didn't work. Worse still, the VRR found them even less reliable than the ones that the Erie were using. In fact, 700 in general was disliked by the crews. *Too Much Puff, Not Enough Steam* - _Matt H. Shay_ was given a 90 sq ft. grate area for the firebox; this proved insufficient, and so both the second and third received a 122 sq ft. grate area. Despite this large increase in size, it still wasn't enough to satisfy the demand the driving wheels provided.

You've all heard of The Little Engine that Could, now get ready for: The Extremely Massive Engine that Couldn't

I always say this when I see a triplex... "UNLIMITED TRACTIVE EFFORT"

"Just don't expect to see anyone building one anytime soon" To be fair, nobody expected a new build PRR T1 either. Although, one of these would just be insanity.

Imagine you’re at a crossing and a train miles long is just going at 10 mph over the crossing

The Triplex locomotives were compound engines. High pressure steam entered the center set of cylinders and the exhaust from these cylinders was split between the front and rear cylinders. Exhaust from the front cylinders went up through the stack. The exhaust from the rear cylinders went though a feedwater heater and then to atmosphere via a large pipe at the back of the "tender".

Despite its flaws, this locomotives is one of my favorite articulated locomotives.

I read from these Triplex Engines in a german book of railway engineering of the year of 1918, when a few german (prussian) railway engineers reported about of those locos. All three Triplexes had been owned by Baldwin but never had been bought from the ERIE RR where it had been tested and had showed that the too small firebox could not produce enough steam pressure to operate those engines effeciency enough. The exhaust of the front and rear Zylinders went into thr larger middle zylinders and used the steam expansion to drive all zylinders. The exhaust of the middle zylinders had been tiled also from one side to the front smokestack and from the otherside to the back smoke stack after heating the water inside the tender. One Engine had been sold to the Virginian Railways at Norfolk, Virginia where it had been built a little bit longer because of a much bigger firebox for burning virginian anthrazite coal, what brought more better results than burning the pennsylvania coal of what the ERIE RR wanted to haul to Buffalo or other Harbours at the great Lakes. At the ERIE RR those three Engines did shunting the coaltrains, theit max speed was around 25 mph as empty engine and more less than that with additional cars behind it. The Virginian #700 was much more efficient running by much higher speeds of up to 40 mph, the plan use it as pusher engine had been giving up very early, the loco could run ahead middle long standard trains but was too expensive in operation, so it was giving back to Baldwin in thr 1920's like I read from other railway engineering books of the 1920's. The problem were the tracks and the loco weight of metric tons per axle. The higher the loco weights the more bigger the tons per axle. Thr more expensive are the rails, what could carry those heavy engines.

A train that's nearly 7 miles long and has a top speed of 5mph... That would be a fun one to wait for at the crossing!

At the time of the Triplexes, the standard freight car was only 36 feet long, not 50 feet. It was also lighter than a modern freight car, and had a composite wood and steel frames.

I’m glad we learned from our mistakes, but damn, it would of been interesting to see how a Quadruplex or a Quintuplex would turn out in real life.

The Virginian Railroad had massive 2-10-10-2s that had the biggest diameter boiler used in the US. I have read that they could maintain there steam pressure will pushing heavy trains.

Given that the Virginian's XA was successfully converted into 2 long-lived conventional locomotives, I wonder if the designers had made provision for such a conversion from the ground up, in case the triplex form didn't work out (which they might well have suspected, but had to deliver it anyway for the pointy-haired boss).

somewhere is the ghost of a locomotive designer thinking his 2-8-8-8-8-8-8-8-8-8-2 design would've worked

Banking locomotives in the United States are referred to as 'helpers'. An American would not recognize the term 'banking'. They would assume that somehow the engine had accounts at a bank.

Somebody: *Builds an 0-8-8-8-0* Somebody else: *Consumes far too much alcohol, and proceeds to design a 2-10-10-10-10-10-2*

Amazing video as always. I've never thought of these unusual locomotives as tank engines until this video. MTH made these in HO scale as well.

The first set of cylinders(4 not 6) exhausted through the flues in the boiler. The rear drivers exhausted through it's own stack. Also Triplex referred to the fact that had 3 sets of drivers not 3 cylinders per driving wheels. 3 cylinder locos were tried here in the USA , but the hassle of serving the 3rd cylinder between the driving wheels was a head ache. Therefore most had the 3rd cylinder removed.

Thanks for sharing 👍

Now imagine waiting at a railroad crossing for a train to pass which is 6 miles long train and going 10mph.

I love it how the theorised quadriplex still weighs less that the big boys

There are two significant errors in your opening introduction. The Union Pacific 4-8-8-4 "Big Boy's" only independently swiveling bogey was the forward one. The second set of drivers were permanently aligned with the boiler's central axis and did not swivel independently of the locomotive's frame. Secondly, the Big Boy's two sets of eight drivers were powered by just two high pressure steam cylinders per bogey, not three as stated in your introduction. UP had some classes of non-articulated 3-cylinder compound locomotives, notably the 4-12-2 "9000 Class" solid wheelbase engines, which represented the only use of this wheel arrangement in North America.

The funny thing is even though the Triplexes were a failure, the PRR still built the T1, S1 and Q1 - Q2 engines. Which even though had some success they were still a little extreme, and had similar problems to their predecessors.

Nice mention of the Quintuplex, its outrageous in all the right ways and one of my dream engines to build in lego eventually.

I love this history of the Triplex! Thank you for uploading this.

Another type of locomotive you can talk about are the Duplex style of engines that the Pennsylvania Railroad had. They're long rigid frame locomotives with 2 sets of driving wheels. The T1 tended to get a bad rap but honestly it's not really deserved. I'm sure you could give a fair short video on them and it be a lovely addition to your channel. Btw the Pennsylvania had 4 different duplexes in all. All with different wheel arrangements.

When minimizing labor costs are the first and last concern of those in power, these are the absurd length they'll go to.

If Big Bertha was American, she'd be a Triplex.

I was about to say "But that's a tender engine!" But ended up eating my words when I saw there's another driving wheels on the coal bunker. Very absurd loco indeed

I never saw this as a tank engine, but I see it as one now.

Imagine a 2-10-10-10-10-10-2 locomotive pulling, like, a 15 mile long freight train doing 5mph

The Big Boys did not use three cylinders per bogie, it used the conventional two! The three-cylinder arrangement uses the Gresley Conjugated Valvetrain where the timing for the center cylinder is derived from the valve positions of the outer-two. The design reduced wear on the tracks and provided a more uniform application of torque, hence reducing wheel-slip at slow speed. The major drawback was accessibility issues to the center cylinder for maintainance and the fact that its main-rod operated at a greater angle hence greater wear/stress to its bearings and sliding surfaces An interesting fact: When the Mallard set the record for the fastest steam engine ever it "threw out" its center rod and had to limp home.

bloody hell thats quite a tank engine

You know your content is good when someone who doesn't otherwise care about trains is excited to watch your new videos.

I never considered the Triplex as a tank engine until now. Thank you for your words of wisdom.

Literally the definition of: "Go hard or go home" OR "Grab my beer"

It was a good idea in theory but they could only do about 8MPH without running out of steam because the boiler we just not big enough to feed all those cylinders.

A super video. A minor thing though, the articulated locomotives have a + between the articulation, such as VGN 2-8+8+8-4 or the UP 4-8+8-4 Big Boy. Ridgid frame locomotives like the Pennsylvania Q1 4-6-4-4 did not have a + because they were not articulated, and technically, they would be tender back also, so it's actually a VGN 2-8+8+8-4TB, designating that the locomotive carries its fuel and water on the locomotive frame. 💙 T.E.N.

I think 2 sets of driving wheels (Like BigBoy & a Virginian Railway Class AG) should be the limit of a steam locomotives. It's like the old saying: "Bigger isn't always better".

Staggeringly awesome video. So many driving wheels....At 3:44 "Keep up" LOL!! I was so mired in wondering how the weight of the engine didn't just smash the rails to noodles I couldn't even remember my orientation, let alone follow the drive wheel count!!

Imagine the wait at the level crossing if it pulled it's full weight!

I appreciate the banjo-kazooie music in the background. Nice stuff

I love these crazy ideas!

THANK YOU FOR SHARING THE VIDEO

You should make a separate video about Franco! The Belgian/(Italian) monster you talked about it in the end 😅

Every time you say "railroad" I just flip out. Lol.

I'm not gonna lie The BGM SOMEHOW fits with the theme of the video

In the end, the low top speed of these locomotives quickly doomed their usefulness. At least the Alco "Big Boys" could actually run at a decently high top speed.

Sometimes we gotta ask ourselves "has science gone too far?". For the proposed idea of a quadroplex and quintoplex, I'd say yes.

I'd never thought of Triplexes as tank engines before 😂🤣

24 driving wheels? I can think of something much funnier than 24

Honestly, I didn't know any of this until now. Very interesting indeed.

Heavy pigeon chested was used So the blackbird could use white paint on the painting on both wings as a front so the black crow behind it and then use it as cover for 3 9

One problem with such locos, railways have corners!! These BIG LONG locos did NOT like going around corners!!

It took me a minute but then I was like is that banjo kazooie music

"More... More... MORE!" - Kylo Ren

Nuts N’ Bolts’ version of Spiral Mountain. I cannot help but feel a sense of nostalgia.

Cool video lots of good info even if some of it might be wrong. A friend of mine has a O scale model of one of these engines and we actually tried to pull a 300 car train with it and broke couplers trying to do it so even models have the same problems

The 2-8-8-8-2. The "Maus" of steam engines.

Nowadays, the average train is over 6 miles, but they have diesel and run on very specific tracks. This just seems surreal for something with steam power single-heading a train. I don't even know that the cars at the time had the strength to hold up due to the engine decelerating, and would probably require loads of engines just to get the entirety of the train in motion without breaking. I can only imagine how majestic it would have been to see one of these in action, even if only for jobs that didn't use the full capabilities of what was intended.

my right ear liked the banjo xD the music's catchy 🤘

Another issue that the triplex also suffered from was Wheel slippage on the rear set of drivers. As coal and water were used out of the tender the weight on the rear set of drivers would become less and less making them very easy to slip compared to the front and center set

THATS ENOUIGH SLICESSSSS

*Love the "Banjo Kazooie" music in the background of this video.* Such a great game that was released on the N64 back in the day. The Big Boy however is the true largest steam locomotive that was actually ever built and put into operation. Yes, there are some very worthy contenders for the largest title like the Yellowstone's and the Allegheny locomotives. (All U.S.-built locomotives still) But when you take all the different ways to measure a locomotive and average those numbers out, the Big Boy is the largest locomotive. Again the runner-ups in a neck and neck race are the Yellowstone's and Allegany. The XA Triplex and Erie class are also then good contenders in some measurements. But in the end, U.S. locomotives dominate in this whole class of the world's largest anyways. The top 10 contenders are all U.S.-built locomotives. But as mentioned in the video, the U.S. has the heaviest loading gauge. So hence the least amount of restrictions for weight and overall size.

Perhaps these locomotives were ahead of their time. At Nederland, we have Electrical Multiple Units coded DDZ; The motor coaches (mDDM) have 3 sets of bogies under them.

Please do the Soviet П38 Паровоз ("P38 Parovoz" (which is "P38 steam locomotive")! They were a 2-8-8-4, and as far as I can tell, while 4 were ordered, I'm not sure if all 4 were eventually built, though there are no surviving examples. It's smaller sibling the П36, a 4-8-4 does have many working examples still today. There's not many KZfaq videos on the 38, and part of me wants to design a 5in gauge model as part of a really long term project. Thanks!

I thought Triplexs where Tender Locomotives

Santa Fe also had some crazy designs as well. By the early 20th century the SF got the crazy idea of take pre-existing locomotives and add another driver set and boiler section. It was cheaper to only have half a locomotive built so it became popular for a few years. The biggest locomotive stemmed from this venture was the 2-10-10-2 and the most successful as the 2-6-6-2.

Lets not forget the "steam tender"! The rear set of driving wheels would loss traction in its desperate effort to create steam! The triplex is plagued with problems!

didnt expect to hear banjo kazooie music on a video about triplex locomotives but here we are. nice lol

11 minutes? damn im early!

One big issue was the rear set of wheels was when the water and coal was used up it in the tender above, the rear wheels would begin to slip and loos strenght

Train of Thought: "making them some of the largest tank engines ever built". Me: nodding. Double take. "wait. 'Some of the largest?'"

My first thought was, "bigger and more of an absolute unit than Big Boy? No way..." I really didn't know what I was gonna see.

Someone actually had the audacity to even conjure the idea of a 2-10-10-10-10-10-2

That is American as it gets

I did once see a drawing for "THE HEXAPLEX"

If you ever hear anyone say Bertha was too much just show them one of these.

The biggest flaw was that all the cylinders were of the same size rather than having compound large diameter cyclinders at the front Also having the third set of drivers under the water and coal capacity meant that the adhesive weight over that set became less as the loco was in traffic

Kind of a shame none of these freaks were preserved somewhere. This kind of delightful lunacy should be remembered.

Its a prime example of "the idea might sound good but in proactive not good."

Ah, i see they used the kirble school of "when in doubt add more thrusters" except instead they went with "when in doubt ADD MORE WHEELS!"

What do u mean the big boy had six cylinders? It only has four. Nice vid keep up the good work!

I have a friend who has an MTH O scale model of a triplex. I’ve seen it and it’s absolutely nuts.

There were two proposals for ... 2-6-6-2-2-6-6-2 Garratts? Imagine that concept enlarged to US loading gauge and 4-8-8-4 power units? And it would have gone around the corners. The Garratt design allows a firebox as big as the loading gauge allows.

Guhu Wahey Nice music mate

The real point of such formats was usually because the rail track had limited axle loading and it was only way of hauling iron and coal over distance. The calculation of engineers often related to the axle load, width of engine and cost of coal per journey per the unloading time at delivery depot often a boat. The journey was often downhill allowing a certain liberty on load journey while return trip was with empty cars.

If only they worked well. It would be nice to have high speed rail on one of these

Make an engine that can pull 6 miles of cars. Siding and yards in the US have problems handling any train over 2 miles, which is taken from the union representative to the Union Pacific this year when explaining why traffic on the railroad was backing up.