Walschaerts Valve Gear Explained

PLEASE NOTE - this model and explanation contain a glaring error. That is, at the neutral position, the valve ports should not open at all. Thanks to Dave Squire for his keen observation. I'll hope to revise the model and make a new video, soon. -BL
For steam locomotive enthusiasts who've always wondered what all the complicated rods and linkages do. As an instructional video, this is admittedly still a work in progress. So, your constructive comments are welcome. Also, the model shown is one I'm trying to develop for sale, as a kit. If that's of interest to you, please send a private message.

[@simonholyfield3319]

You might have made your 'glaring error', but this is by far the clearest video on the operation of Walschearts vale gear that I've seen. Your voice over is excellent - slow and clear. Well done.

[@Rosie6857]

There is no "glaring error" at all. When in mid-gear the valve still moves owing to that contribution from the movement of the piston, so the movement is in phase with the piston. Even under these conditions some small amount of power will be generated because of the delay between the opening of the valve and the application of pressure to the piston. Even hot steam has a little inertia and the faster the engine is going the greater the delay relative to the piston movement so the greater the power developed but it's still pretty small. All valve gears are designed so that the valve opens just before dead centre to allow the steam in. With Walschaerts gear this is a fixed amount but with Stephenson's Link motion it varies, being greater at shorter cutoffs. It's debatable whether this makes much difference.

[@c182SkylaneRG]

@@Rosie6857 Thank you! I was trying to figure out what the "glaring error" was, too, because if he built the linkage to the exact proportions as the real thing (which he appeared to), then how it works is how it worked, no errors. If you want to get an exact "neutral" operation of the feed gear, you just need to raise the position slightly further to where the phase of the Walschaerts gear exactly cancels the movement of the drive wheels (and I'm sure such a position was clearly marked on the controls inside the cab). The rod to which the control piston is directly connected is fixed at two ends: one to the driving rod, and one to the control rod. By putting the control rod in the exact neutral position, ONE END of that connecting rod is fixed, which still leaves any point along that rod moving in-phase with the driving piston, and thus the control piston is also still moving in-phase with the driving piston. You need to move the control rod slightly into reverse so that its end is moving backwards at the same time the driving rod is moving forwards by exactly the right proportion to keep the control piston's anchor point stationary. Linkages was one of the more interesting classes in College. :)

[@g8ymw]

@@عبدللهبنعبدلله-ن8و What has this got to do with the workings of a steam locomotive?

[@davidgarnett5011]

@@g8ymw Nothing really however there is a Grateful Dead tune called "The Wheel" which has a line in the lyrics " Small whell turns by the Fire and Rod.--- Big wheel turns by the Grace of God" But I wouldn't read too much into that.

[@mikado1555]

The valves SHOULD open in center (there is no neutral). In center, the valve opens a little bit - this is called the lead - as the valve is only controlled by the motion of the piston through the lead and lap lever. When the valve gear is properly set, the loco can run in forwards/reverse as the valve events are the same, just not very powerful. As far as the eccentric crank, the eccentric crank is close to 90 degrees off, but due to the piston centerline being higher than axle centerline (dead centers are not 180 degrees apart) and the height difference between the axle centerline and the basked of the link, the angle can vary from loco to loco and with the crank pin at the 6 o'clock position the eccentric crank pin is higher than the axle centerline making the angle listed in this video greater than 90 degrees.

[@Bigbuddyandblue]

Clear, simple and to the point, no filler, no music, no grandstanding, no pimping a product, no sales pitch, no pop-up commercials, no history of the steam locomotive, no drama, no begging for likes and subscriptions, just a great animation and concise explanation! Thanks! Subscribed!

[@philgiglio7922]

💯 agreed. I saw something similar on a working steam tractor many years ago. It was huge and it could go both directions. This must have been how it worked...thank you Also subbed

[@yogiperogy]

Wow! You nailed all the elsewhere ubiquitous irritations of YT!! Thank you very much Brad for tackling this complicated “magical” apparatus and enabling appreciation by the less mechanically-inclined viewer (like me!).

[@dominatorut]

Yes, because we should not enable an informative content creator to earn from their many hours of work. People should be willing to make videos for free!! In fact, let's all work for free! 😊

[@timault8209]

I claim this excellent comment for my own! I have copied it and I will post it to worthy videos. I suspect it won't see much use, unfortunately!

[@Bigbuddyandblue]

@@timault8209 cool!

[@ThePaulv12]

If this were a school project you'd get 11/10. Concise, short, to the point. One thing however, if you're not a gunzel you might not know that steam is admitted to both sides of the piston. It could be worth mentioning at the outset of the vid but it is highly likely that the intended viewers all know this by the time they get here - so I'm being somewhat pedantic. .

[@fredred8371]

Good idea, it took me a while to realize that since I'm used to internal combustion engines.

[@wilburfinnigan2142]

thePaulv Would help too if it was explained better HOW the high pressure steam entered the valve and where the exhausted steam went !!!

[@neildahlgaard-sigsworth3819]

ThePaulv12 he did. Good and re-watch the video at about tbe 1:20 mark.

[@TlalocTemporal]

@@wilburfinnigan2142 -- You can see at 1:20 +. High pressure steam is injected in the center of the smaller spool piston at the top from the pipe. The same spool piston can allow access to the exhaust ports on the outer edges.

[@ginalee813]

The red shows high pressure, blue the exhaust, being admitted to both sides of the piston on each stroke. It’s self evident.

[@HerroVincey]

There's something so lifelike in the fluid motion of such a system! It feels like seeing the concept of "motion" truly coming to life!

[@Bendigo1]

It looks so complicated, but in reality, it is extremely simple. Excellent explanation and demonstration!.

[@chilitoday]

It may “look” simple because it’s been figured out.

[@andrewpetik2034]

Thank you for sharing the fruits of all your hard work! I have loved Steam Locomotives for as long as I can remember and always marveled at the workings of this system of rods, links and pistons. This video is much appreciated!

[@troyclayton]

I'm so glad youtube tweaked the algorithm to bring so many of us here in such a short time. Thanks for the video, I'm now less ignorant of something I thought I knew how it worked, lol.

[@Qdogsman]

I don't think you made a glaring error at all. It is true that in the center position, the radius rod is stopped. But since the union link is still moving and the valve is connected to a point on the combination link near, but not at the top, the valve still moves although a lot less. I think you got it right. BTW I am one of those who also wondered about that linkage all my life ever since I used to meet those locomotives to pick up the newspapers for my paper route in around 1950. I really appreciate your explanation. Great job.

[@davidzachmeyer1957]

Correct, the combination rod is included for the specific purpose of allowing valve travel at the neutral position. The model is correct and operates exactly as it should!

[@johnm2012]

@@davidzachmeyer1957 I'm not saying that you are both wrong because I don't know enough about the subject but if one extreme is full power in the forward direction and the opposite extreme is reverse there _has_ to be a neutral position somewhere in between. Whether that position is the centre position or not determines whether he made an error in the model. The thing is, two 90-degrees out of phase rotating motions can never cancel to zero, whatever their relative amplitudes - this is the mathematical approach, which I understand better than the mechanical approach.

[@davidzachmeyer1957]

@@johnm2012 read up on the Walschaerts mechanism to understand the function of the combination lever. As I stated, the OP's model properly represents the correct motion of the valve when the reverser is at the center position.

[@u1zha]

@@johnm2012 If one extreme is full power in the forward direction and the opposite extreme is reverse there has to be a neutral position somewhere in between, yes, and that position is not necessarily engine at complete rest, nor coasting for that matter; I think in this case "neutral" amounts to powering forward half a cycle and powering backward half a cycle. But I'm not a steam engine expert either.

[@leobuis9568]

Thank you! I've been curious about the valve that controls the direction of the steam for years now. I figured it had to be pretty complicated, but I had no idea it was this complicated until I watched your video! We may think we're really smart today, but your video shows and engineers in the past word just as smart if not more so.

[@FS2K4Pilot]

Wait until you get to valve gear setups like the Baker and Southern valve gear motions.

[@blockstacker5614]

Franklin type B is simpler and more effective, but much less common

[@janotterspoor1721]

It only takes 4 minutes to explain how this mechanism works if you can imagine how the minds of technically interested but not gifted people work. I imagine you do. Great Video. Thank you very much!

[@jimkadel3003]

Perhaps an improvement in explanation could be had by using a visible label when referring to a particular link in the diagram?

[@cogzoid]

Great demonstration and explanation. Keep 'em coming!

[@vincenzonovi5528]

The clearest video about steam locomotives I've ever seen. A wonderfull English to hear by my Italian ear. Thank you so much.

[@bergasms]

This is one of those videos you never knew you needed to watch.

[@bigblue6917]

I have, on occasion, scratched my head over this wondering what it all did. Well now, thanks to you, I know.

[@AndreiTupolev]

This is very useful. I've been able to work out from videos how it all goes round, but what it all does and how it all goes together has always seemed very complicated. It also makes the concept of cutoff and how that works clearer too.

[@deepdirtysouth2394]

I would just like to take a minute and personally thank you on behalf of everybody let’s watch this video sir. Absolutely brilliant explanation thank you so much.

[@PokoleizKuleckim]

Astonishingly well explained. Thank you so much for sharing. I do admire your ability to explain it so clearly and crisply.

[@september1683]

I came here by accident. And I left with a smile on my lips, because of your beautiful explanation. Best wishes from Bavaria. Have a nice day!

[@pneumatic00]

Thanks for posting this! I've never been able to quite wrap my brain around the operation of the Walshaert part of the power train. I think if I watch this ten or so times I'll get it. Nice model!

[@timault8209]

Thanks for posting this exceptional video. I shall now endeavor to build a full scale model for my living room wall!

[@BLitwin]

Go for it! Send pix

[@Firedog105]

I wish I was smart . No way in a million years and all the college degrees in the world would I ever think of that design . You have to be born with that type of mind.

[@ThePaulv12]

Kevin, don't underestimate yourself. If there is a need for something, you are curious (the most important part) and there is some $$$$$$$$$$$$$$s in it for you, you might just surprise yourself. Saying you can't is a self fulfilling prophecy - now only if I took a dose of my own medecine ...

[@danstrayer111]

check this out: kzbin.info/www/bejne/gHbMhIewgJJ0aKM

[@ddkoda]

@Herbert Norkus It doesn't seem fair. Don't give up hope. Something more worthwhile may come your way in due course. In the meantime look on the bright side. At least you can pay your bills with your meterman employment.

[@jameshollen9723]

"necessary is the mother of invention" Look around you. Look at something and ask yourself, How can I make that better, faster, more efficient, etc. I barely passed High School but I have 3 patents in my name. I have designed countless ideas in the basement. That's the fun ! (O yes, it's nice to make a buck or two doing it !)

[@paperbackwriter4145]

Just one word: motivation. Thats all.

[@thematthewexpress5999]

It's very satisfying to watch the Walschaerts valve gear go round on steam locomotives, also very interesting. Good model and video.

[@davidhall8874]

Finally! The best demonstration and explanation I have ever seen, and I have seen a lot of these! Thank you so very much!! Well done sir!

[@c182SkylaneRG]

You should update your description: there are no "glaring errors". Your video was spot-on. The neutral position of the Walschaerts gear is not the neutral position of the control piston. You have to move the Walschaerts gear slightly into reverse to neutralize the control piston (and I'm sure that position was clearly marked on the cab controls). Play with your model, and you'll see what I mean. For my part, I really appreciate the color overlay, because at first I thought the control piston was solid and I wasn't sure where the steam was being injected from. :)

[@c182SkylaneRG]

The vertical linkage directly behind the pistons is the key: that rod has one pivot point that does not move, but that pivot point changes location (including beyond the end of the rod) depending on the gearing position selected from the cab. When the Walschaerts gear is placed in exactly neutral, that pivot point is placed at the upper connecting bolt. The control piston is connected at its own bolt a few inches down, and is not stationary in that position. If you put the Walschaerts gear slightly into reverse, you move that fixed position down the rod. At exactly the right amount of "reverse", that pivot point is placed in-line with the control piston's connecting bolt, and the control piston stops moving. Linkages was probably one of the most interesting classes in College. :)

[@cfa61]

Thank you! A very clear, concise, explanation! Nice work, and generously shared.

[@tobyLikesTrains06]

I would love to see this as a kit

[@dj6769]

Excellent “Readers Digest” explanation I now have a very basic understanding of how these masterpieces move forward and reverse. Some post are seemingly debating specific operational designs that’s obviously above human comprehension. Thanks for the video great job.

[@marksherrill9337]

Both simple and brilliant and beautiful to watch.

[@VK-xw4yz]

Best explanation of the mechanism available on the KZbin ! Thank you so much sir for uploading !!!

[@BLitwin]

You are most welcome

[@robertramsay5963]

Thanks Brad. I'd never quite figured this out, especially how the reverse would work. Thanks for the clear illustration.

[@BLitwin]

Glad to help

[@MrChrisKnowlton]

Very well done! I always wondered how the secondary linkages worked.

[@ratheonhudson3311]

I agree, it's an amazing work or engineering and steam engines give a feeling of being alive, more than any diesel or electric does. Also, thank you for this detailed explanation. I didn't know how these worked

[@rogerletsom2127]

This is a very fascinating working model. There are three points of difference I've seen in other diagrams and models, however: connecting rod(main or driving rod), tie rod(side rod or connecting rod) and combination link(combination lever). I'd like to see more steam locomotive related models. Thanks!

[@major_nobody311]

My own projects of steam engineering will greatly benefit from this video, thank you imensly.

[@mellissadalby1402]

That's a great demonstration. I never knew that.

[@michaelmonaghan2717]

I have always wanted to understand that system! Thank very much!

[@hassanharith6820]

Me too,. appreciate so much. Niw i really got d idea how it's working...👍. 🚂.

[@jordenconrad8827]

Brilliant demonstration and explanation. Fascinating

[@davesquire4943]

There seems to be some confusion about how the parts all work. The combination lever moves the valve back and forth a fixed part of the piston's stroke; it never opens the valve. This motion is needed because the portion of the valve that covers the steam ports is wider than the ports. If the combination lever opened the valve any amount on its own, there would be no way to put the engine in 'neutral'. The angle of the eccentric does not determine inside/outside admission. If the valve rod connects to the combination lever below the radius rod (as in the model), the engine is inside admission. The confusion is caused because the valve gear may be direct motion or indirect motion. With direct motion valve gear, the eccentric rod moves in the same general direction as the valve. If you change the eccentric from leading to trailing, you change the relative angle 180 degrees. You can get the same 180 degree change by moving the radius rod between the top and bottom of the expansion link. So either leading or trailing eccentric is correct for inside or outside admission; you just have to 'reverse' the direction of the radius rod. In fact, many Garratts are built with one engine with direct motion and the other with indirect motion.

[@BLitwin]

Wow! That's good info, Dave. I should've realized the center position shouldn't open the ports, at all. I'll have to modify my model, now, and add a note to the explanation, above.

[@simonwass6315]

@@BLitwin You can have port opening with the gear in mid position, it provides what is called lead (not the metal!). You need lap and lead movement which is provided by the combination lever, any extra valve movement comes from the expansion link. Stephensons gear has a habit of causing negative lead at small cut offs.

[@stephenwiseman1816]

Some good information here! Can I also add, regarding lap and lead steam, as has been said for lap it is necessary to have valve heads that are wider than the valve ports. I know that on the miniature loco's that both my dad and my brother have built, the valve heads are twice the size of the valve ports themselves. Furthermore, it was always my understanding that when the valves are sitting central over the valve ports, the outside edge of the valve heads (the exhaust side on inside admission) are just about closing the valve ports on both ends, i.e. the outside edge of the valve head is inline with the outside edge of the valve port.

[@hackenbush23]

The combination lever moves the valve lap + lead, hence the name combination lever. For one complete stroke of the piston, the combination lever moves the valve (lap + lead)x2. This movement occurs no matter where the die block is in the link and opens the valve the lead amount even in mid gear. This crosshead derived motion is referred to as the 'The short' travel. The 'long travel' is derived from the return crank, which is 90 degrees out of phase to the combination lever, and is what opens the ports beyond any lead. This also applies to Baker valve gear.

[@hackenbush23]

@@stephenwiseman1816 What you refer to is exhaust clearance if there is a gap between valve and port on the exhaust side, if there is no gap and the valve is directly in line with the port this is 'line on line". If the valve extends over the port on the exhaust side this is exhaust lap, very rare on locomotives though.

[@TMCNJ]

I never knew this is how they worked. Thank you for explaining it so clearly 😌

[@organbuilder272]

Well, If the clarity and beautiful symetry of your models make this mysterious secondary valve train clear - I' would accept that little error. Who cares really, the important thing is that you clarified the workings of the eccentric, radius rod and the combination link. Can you imagine Walschaerts doing this by hand, no calculator and all pencil drawings. You did a wonderful job of explaining this mechanism and a clear disply of how the spool valve stops it's transverse motion or not when the Eccentric gear is set. Great job. Thanks you sincerely.

[@colvinator1611]

Thanks a lot Brad. I agree totally with Big Buddy in his assessment of your video. Amazing engineering indeed.

[@alancordwell9759]

Thank you for that very clear explanation!

[@williamgeorgefraser]

I just love to see how these valve gears work. Back in the late 60s, my High School railway club was given a brass model of a loco chassis with Stephenson valve gear. It was a serious piece of equipment and was about 5 feet long. It was stripped down and cleaned and I took over the job of setting it up. I was informed that it was inside admission and spent hours trying to set it up before discovering that it was actually outside admission. It taught me a great deal about valve gears and it is still a subject which fascinates me, especially poppet valves.

[@nicom4996]

Thats a video i've always wanted to see, thank you very much

[@Mookie1340]

Thank you, great video and model. It looks so simple once explained.

[@69Applekrate]

How cool! thanks for taking the time to explain and show. I learned from you today

[@Davidsladky135]

Thank you for years I had no clue how they ran in reverse!

[@rogerfroud300]

I don't think you're right about the motivation for the introduction of Walschaertz valve gear. Stephenson's valve gear predates it and performs the functions you describe with better symmetry and in both directions. Walschaertz valve gear cannot do this. If it's optimised for forward running, it's not optimal for reverse running. This doesn't usually matter that much in practice though. I'd suggest that the real reason for the widespread implementation of Walschaertz valve gear has nothing to do with efficiency, and everything to do with maintenance. Stephenson's valve gear can't practically be mounted outside the frames, and that's a real headache for maintenance. Mounting the valve gear between the frames means the steam chests generally need to be between the frames too. GWR locomotives generally followed this pattern. On the other hand, Walschaertz gear is more compact and can easily be mounted externally which is cheaper to manufacture, easier to set up and easier to maintain. Although it's inferior in terms of symmetrical valve events, this is not a big enough issue to prevent it being used. If you want to know more, download one of the valve gear simulators used by Model Engineers or consult the works of Don Ashton who it an expert on the subject.

[@burtvincent1278]

Wow. There must be dozens of ways to control the valve. Today they would use a computer.

[@rogerfroud300]

@@burtvincent1278 - Indeed there are, Hackworth, Joy and Baker valve gear are to name but a few. The very best were late developments that used poppet valves and clever gearboxes. Caprotti valve gear comes to mind. In those they open and close the valve much more accurately and rapidly. All of the conventional ones have quite slow and progressive openings which is less accurate and efficient. You certainly could use computers and solenoids to operate poppet valves. If you search KZbin there's a video by Koenigsegg about a Camless engine that uses just that idea for a car engine.

[@Bordpie]

@@rogerfroud300 Yes there are many type of steam valve gear. All the kinds with spool valves work using a combination of a fixed amplitude sinusoidal (sine) motion e.g. the link connected to the piston rod, and a 90 degree out of phase (cosine) motion with variable amplitude e.g. the expansion link on this valve gear. This arrangement always opens the valves at the start of the stroke, and closes it part way through the stroke which is what you need for variable expansion of the steam. Changing into reverse just requires flipping the direction of motion of the cosine component e.g. 90 degrees ahead rather than 90 degrees behind the pistion motion, and the valve gear works just the same in reverse with variable cutoff (generally speaking).

[@steffenrosmus1864]

This is compensated by the use of turntabels so eniginrs with Heusinger/Waldschaerts gear could run forward for the most time.

[@sygrovesteve5819]

@@rogerfroud300 Yeah....BUT.....computers can be hacked

[@dominiquedescottes8314]

Grâce a cet ingénieux dispositifs NOS CHÈRES locomotives a vapeur ont etées les lévriers du rail Pas de micro processeur, de disque dur,que de la mécanique, et de la vapeur Respect a l'inventeur de ce procédé

[@OlivierGabin]

Brilliant. Clear explanation, I have understood everything.

[@willybee3056]

You just made my point. More than 90% of education is in the hands of the teacher. The student doesn't fail to learn,,, the teacher told fails to teach... You sir,, are , an exemplary teacher...

[@peterarisz2150]

I finally understand, thank you! /edit: when you realise, the "cilinder" is that small.

[@hansvandijk1487]

Well done! Greetings from the Netherlands 🇳🇱.

[@timmason7430]

Forward and reverse explained in simple terms. Thanks

[@jpguthrie6669]

Adam Smith stated that the modern steam engine was greatly improved by a young boy. This boy was employed to operate a primitive steam engine with a manual valve system, and the boy's job was to push and pull the valve lever to keep the steam engine in motion. The boy, bored with his job, and wanting to play with his friends, worked out a system which allowed the valve to open and close by itself, using pieces of rope tied to the flywheel and attaching them to the valve handle.

[@iPeteStorr]

an enjoyable 4 minutes in your class room, thanks

[@southernmostkilt]

thanks...always wanted a clear concise explanation.

[@goattactac8790]

複雑な機構がとっても良くわかりやすいですね。

[@kuripangui]

Wonderful explanation! this mechanism is really smart.

[@mattbrewster8051]

Uh, thanks, Brad. I think I will have to rewatch this about a hundred more times to understand it all. You have to wonder how long it took to perfect all this!

[@charliehorsenm3446]

Totally ingenious! I wonder how many of today's so called "techies" could have figured out how to do this? My guess - very few. BTW: Thanks for the excellent explanation here and the excellent model you created to explain it. Though like you, I've been a steam locomotive fan for my whole life - nearly 60 years now - I've never understood exactly how the locomotive was put into "reverse". This demonstration quickly and definitively cleared that mystery up for me in a few seconds!

[@1TW1-m5i]

And here was me thinking some locomotives had extra cylinders or something. It makes much more sense now.

[@dannagy546]

Incredible video! Thank you for this explanation!!!

[@Shadow_of_STLKR]

Best vid explaing reverser and valve in steam loco!

[@pattayaguideorg]

Exellent video - thank you for precise explanation and demo and yes - am interested in buying your model

[@BLitwin]

Thanks for your comments, Patty. Please contact me privately, thru BradLitwin.com, regarding purchasing my works. Meantime, here's wishing you a Happy New Year!

[@madhusudanhora2339]

Nicely explained.. add the exhaust function for steam and coal gas as well ..

[@gunniquickservice]

Thank you Sir! That was my missing link. I never got the fact how they would control power and revers. So Awesome. I always thought they operator controls steam only with a valve innthe cabin or so.

[@BLitwin]

Glad I could help!

[@armandoperez1062]

A real big thank you for what you've done.

[@darrenoatesfinefurniture3648]

This brilliant, thanks for posting and answering questions I have had for years

[@gunnarallgottsmann]

Beautiful and very understandable. My respect Sir.

[@liveshoegaze]

An excellent explanation, thank you!

[@OpenRoader]

That was a bad ass description. Nice work!

[@fs2000]

Excellent demonstration!

[@andrewlittlewood5577]

Immensely helpful demonstration - thank you

[@iBackshift]

Hmm...Words are silver, pictures are gold. I've learned something I was always curious about how it worked. that was better than TV.

[@Bartonovich52]

Honda invented variable valve timing!! *VERILY.... WALSCHAERTS HATH JUST KICKED IN, YO!!*

[@chrishoggett1375]

Variable valve timing was already used in Stevenson valve gear by combining the movement of the forward and reverse eccentric connected to the radius link. Opposed to Walschaerts the die block remains in a fixed position and the valve movement is changed by lifting or lowering the valve gear towards mid gear. (Depending on driving direction)

[@royreynolds108]

If you are going to make this into a working model, I would suggest you add a Johnson bar with a quadrant and reach rod to control the crank which controls the radius rod. It will only be three added parts but will look better. Welsch Scientific used to have a demonstration model showing Stephenson gear and it had the Johnson bar and reach rod.

[@BLitwin]

I might do that. I don't have any near term plans to put this into production, though. Thanks for your interest. :)

[@kavalkid1]

Always wondered about this! Thanks so much!

[@stnnorthie1804]

thank you I have so wanted to understand this operation clearly and precisely and you have done that Great Job

[@racrx7]

Very cool AND educational!!👍🏻 🚂

[@nikolatasev4948]

Great video!

[@stevedoubleu99B]

Nicely explained. Thank you.

[@DaljeetSingh-tq5ll]

Sir explained very nice

[@Andrew-gv4bh]

Good job!Thank you!🙂👏👏

[@genericusername5520]

Excellent video my dude, very informative

[@karupusamykarupusamy9658]

பொலீஸ் எண்ணில்லாத எஞ்சின் சூப்பர் என்னுடைய வாழ்த்துக்கள்

[@Lucius_Chiaraviglio]

Maybe the neutral position is just a bit off from where it seems like it should be? Looking forward to seeing the corrected model and video.

[@wellylhakim3619]

From childhood until now I have been amazed by steam locomotive, especially with valve mechanism which is quite complicated ,how come they discover it

[@jimatmile56]

Good job explaining!

[@akpanetebom001]

This is beautiful.

[@friendlypiranha774]

00:20 to 00:25 is South African Railways Class 25 Condenser with condenser tender to convert used steam back to water for the boiler.

[@smilewidestudios8589]

When you realize that this is a pain to replicate with legos.

[@smilewidestudios8589]

@MichaelKingsfordGray When you realize that I make videos and it would make no sense to use my real name, so you're just gatekeeping KZbin channels for no reason.

[@kamunanya425]

finally I was able to sleep well after seeing this video

[@cpi23]

A+ video dude

[@ChongMcBong]

very nice model and explanation :)

[@chipworrell6025]

Very plain and clear.

[@jorgecordero1376]

en Latinoamérica también nos apasiona todo lo relacionado con trenes, somos fanáticos;por favor envienlo traducido en español, muchos latinoamericanos quedarán eternamente agradecidos de todo corazón,de antemano muchísimas gracias; no se suelten nunca de la mano del señor .desde santiago de CHILE.- chao...chao...pesca'o

[@suhas1232]

Excellent

[@RelaxingDisney]

I know that this video was 3 years ago, but I saw in the description that you were considering making this a model available for sale. Are those plans still in the works or abandoned? Would love to get my hands on a model of this! Thank you for the amazing work!

[@BLitwin]

Thanks very much for your interest. I haven't done anything about making it a kit, as it would be more work and time than I could possibly recoup.

[@WagnerDeQueiroz]

amazing Model!