Steam 101: What does a steam loco THROTTLE look like, and how does it work? 

When teaching people how to run a steam locomotive I have had to explain the balance point on a throttle and how it can spring open or closed. Depending on the amount of opening it is possible to go either way. Always check your quadrant spring at the beginning of a shift. The balance point is the most efficient throttle opening but must be used when near track speed and then overall speed controlled by cutoff. Taming the WILD in the iron horse is a constant endeavor. As to those who are wondering how to tame a runaway, centering the reverser and opening the cylinder cocks usually works with a little help from the brakes.

no no no. you cant just leave it at "runaway train, ask me how i know" we need to know.

4:30 Air compressor's gotta get it's "Air time"

I've heard two tales this week about engines that ran away from leaky throttles. Never realized that was a common occurrence lol. Should show the folks how fun sealing up one of those domes can be 😏

I fit inside the dome 346! The throttle was out though. That peak down to the tubes gave a flashback of claustrophobia when I was working on 346’s dry pipe. I was ok most of the time but got a little stuck a couple times and had to do some deep breathing to calm down and work my way out.

It is a balanced poppet valve. They were also used in the Cincinnati Triple Steam water plant.

Keith Rucker has an amazing posting on how the throttle valves are repaired and lapped. Hyce. He does a lot of work on Locomotives in the Georgia area. Very nice guy. You should connect with him. Nice presentation - well done

a fun look into the bitz that make the Choo-choo go Chug chug. Hyce! no make the Choo-choo leave with nobody at the throttle.

Wow the amount of engineering that went into making these beasts work is incredible, and I love learning more about it! Thanks!

I've never been able to squeeze by the throttle on any of the locomotives, it was always a pipe dream to squeeze by.

"You can have a runaway locomotive, ask me how I know" Well since you asked. How do you know?

Thank you, Hyce, for these detailed explanations of how steam locomotives work. Your videos are both instructive and entertaining!

Awesome!! Never knew what they looked like! Thank you!!

0:55 I don't know why, but I was half expecting a jump scare.

Thank you! Please, continue providing very in depth knowledge about steam locomotives!

After playing with both dome throttles and multiple front end throttles I much prefer a front end throttle, as long as it's set up right.

491 just cosplaying as a babbling brook is great.

Very nice! I've seen some pics on Facebook of the Frisco 1630s throttle valve, and its very similar (thought obviously bigger, ya know standard gauge Decapod things) IIRC. Also happened to notice Smokebox is working on a UP 0-6-0 (S-6 Class specifically I believe) for TS:C, so that should be fun...

Neat, really demystifies the enigma steam power once was to me.

So, how do you know? I'd love to hear that story. Also, thank you for posting such amazing content. This stuff fills a hole in my life that I didn't know I had.

One loco I heard of in Britain (in preservation!), a small saddle tank, had a hole in the dry pipe; so effectively you couldn't shut it off. One guy managed to pull a train out of the station with the reg handle in the fully closed position. She got better by the way, they mended the dry pipe. Still, quite frightening to envisage!

Thx for showing this to us! It blows my mind, how komplex steam locomotives are!

I really enjoy you sharing of how the steam locomotives operation from the wake up firing to the running thank you never tire of your videos

About a year ago, Kieth Rucker did a video of refacing and lapping a throttle. I'm pretty sure it was a smaller one though.

Thank you so much for sharing this! Been wanting to see the inside of a throttle dome for as long as I can remember and you explain this so eloquently!

Can you show how the air line couplers work? It looks like they lock together but are designed so they can be pulled apart by the cars separating rather than having to be manually disconnected. You could also talk about the valves and how this can relate to kicking and humping cars.

We pulled the throttle out of Ventura County #2 recently. Holy cow it’s a tight space getting in there

The giant throttle valve in the 491 perhaps was installed after the incident with the faulty throttle valve that caused it to walk away? Or perhaps it's just the nature of the beast, their construction reminds me of a truck in a fleet I used to manage, it was a Ford Bronco. It was purchased on a fleet contract, and Ford fulfilled it by slapping together whatever parts were around, regardless of if they were meant to go together, because several times it was brought to dealerships who asked when it was re-built after the wreck, and how bad the wreck was, because this configuration did not exist (It was never wrecked and belonged to our org. since new). It was a 4x4 with a 3+OD auto (and we all know how much horsepower the average Ford slushbox soaks up) and a very tall rear-end (I forget the exact number) being powered by a 5-litre "High Output" V8. Well let me tell you, it wasn't high enough, because this was a truck that if you put on the air con in the cab and tried to go up a hill on the highway, you had to plant your foot just to come close to maintaining 55. It did get unusually good fuel economy for such a truck, which is something, I guess.

Huh, never realized some steamers had the equivalent of a PTO. I always seem to think of plows and cranes and stuff having boilers, at least small ones, onboard.

Hyce, You are a super smart dude about anything trains or steam!! Love your videos and have learned something from them!!! Keep it up buddy!

Maybe it is not as important in such small locomotive, but throttles of large locomotives (working on higher pressure) operate in two steps. First the little plug is lifted in the center of the bigger plug to equalize pressures and allow to more easily lift the big plug 😉 On the other hand, some small 0-4-0 low-pressure narrow gauge locomotives had external throttle valves of simpler construction (just bigger cock valve), e.g. German "Riesa" and its Polish descendant "Ryś" before 1948 (since when it had been equipped with internal throttle).

at several points I was waiting for Hyce to drop the camera. make it a special steam 101 episode

So thats how it works. Its simpler, but also slightly more complicated then what I thought with the different seats. That explains how engines could drive themselves through the back of the roundhouses or into the pits. I knew 20 was apart and getting ready to go back together but holy crap, I didnt know she was THAT close. Aint got no luck left over for the lottery now. lol. Thank you SO MUCH for climbing up there and giving us a look. The further insight and information that has spawned in the comments is AMAZING. Dual seat balanced poppet valve, the fact on larger engines theres a small one that opens before the large one to make it easier to open. My god, I think we've spawned one of the most informative comment sections on youtube!

Thanks Hyce! This was really cool!

Thank you, that's a rare look at a critical part. I don't know why I never thought of it before.

I hope you can get some shots of the throttle on 491 soon!

If I remember correctly, didn't 20 also technically 'run away'. I believe she walked out of the yard.

Ty and greetings from Germany

Very cool Thank you.Have a great day

I’ve always wondered why the bell hanger has “wings(?)” on it

This is a first I have seen this and how cool.

I’m new to the channel but I’m going to need to hear that story about the run away.

Hyce PLEASE give us the runaway train stories

Thaks Hyce

Aw no boiler gremlins 😢

Was that 491 having an attitude in the background? @4:33? The look on your face was that of someone who’s had to deal with her mood swings and isn’t having any of it 💀

To think I'm learning more about locomotives from a gamer who plays a niche train game

6:34 I call. I'd like to hear the story.

Informative, thanks for a great video.

Greatly enjoyed this video!

You had me at Doughnuts 😃 Seriously Hyce that was one of best description of how the Throttle valve works. Shit. I understood that! And I know those Ks won't go 88 Doc. I'm not a Idiotic*1/8rh of one maybe More Choo Choo 🚂make mongo happy 😁😊. Thank you.

hey hyce i have an important question for you. if you could build your dream locomotive what would it look like? things like the wheel configuration, the chimney type, the fuel type, the headlight placement, any streamlining, the road name and number... just out of curiosity. also love this video ive always wondered what the throttle valve looked like!

Soo line 2719s throttle leaked, it started to roll onto the main line where it got hit by a coal train.

If the throttle seeps by a little bit, can you compensate by opening the cylinder cocks to let the steam out of the cylinders rather than runaway the locomotive? Worked in power plant steam systems, and yeah a two-seat valve like that is a lot easier to open against steam pressure than a single plug style.

How come they don't have a shut off valve so the engine doesn't runs away?

*Hyce talks about leaky throttle valves* Ah yes, night crawlers are always fun~

3:58 is that a reference to SPNG 18’s incident on the D&SNGRR that your friend was on?

The name's Mark doughnut done, inspector of of the steam train doughnut domes! The word "dome" has been forever ruined (or improved)

Considering the only thing the trottle is doing is limiting flow, not pressure, does this mean that the locomotive would have the same power at 10% throttle as it does on 100%, just limiting speed of the engine?

6:34 well all I can say is: How *do* you know prof. Hyce?

6:35 ok google, how does Mark know that if the plug is open just *that* much, the engine will run away?

so if you have a runaway locomotive how do you stop that? i assume you have to set the johnson bar in the postion where there is no valvue travel.

It’s very rusty in there I wonder when it’s boiler inspection is when all that rust and crud will get removed

Hyce why haven't we seen much of 346?

What water treatment are you using on 20's boiler? There is a lot of surface rust on the inside. Also what is being done on the 20?

nice video.

What do you guys use to seal the seam on non welded or hammer caulked seems like under the plate atop steam dome, also needs skinny long arms for the one steam dome you guys could use my help lol my arms are so long I required second largest the largest horse bow for mounted archery when I ordered one last week I have a 35 inch bow draw they only come in 36 otherwise it's special order

So there is nothing preventing the valve from sticking open eh? Hmm, looks ripe for runaways if anything goes wrong.

Why would a steam locomotive want to throttle its steam? Isn't that a loss of energy? I thought the engineer regulated power by operating the valves on the cylinders. If there is too much pressure in the boilers, why not just have the safety valve take care of it.

You dared us, so how DO you know about run-away engines??? :)

this is amazing. and more so that you are able to film there. i`m not much of a train lover, but this content you bring is great

I'd like to ask "how you know?". WE WANT TO KNOW!

Oh no, do I want to know?

Is there any difference in shape/ upper to lower seat ratio with different boiler pressures?

And I assume that's a cast iron component, not bronze, correct?

5:37wat happened to 491?

Interesting! This loco have a superheater?

Nice

So hyce, how do you keep steam from shooting out the steam dome or out the backhead? As the linking rod from the cab has to run into the pressurized boiler?

Will you ever have a chance to show off a front-end throttle on the channel? (I know you have LOADS of spare time 😂)

6:30. How do you know?

How did u get upp on top of the lokomotiv

Hey Mark mice video man I always wondered how the throttle worked. Hey are you doing a video tomorrow of a new video game? I saw your live stream yesterday also just wondering do you think you could show us some parts or anything on 491 or 20 that are from other engines? Just wondering I know you did that with 346 not that long ago. Anyway grea Vodafone look forward to seeing more from you soon man. Jeff aka NW611J.

I suppose some might wonder with two valve seats, Does the steam only enter through the top one, and then go through the bottom one to the dry pipe, or does steam enter both the top and bottom of the casting (through both valve seats) from the boiler to the dry pipe? :)

What is a "blue Peter incident?"

HOW DO YOU KNOW! TELL US!!!!!

I would like to know how to get a job at the museum and work with you guys because Im in school and we are looking at jobs we want to do plus Im a idiot and a steam nerd 😉. But it will be a few years like 2025-2030

🤘

I thought the throttles on these things were butterfly valves, not whatever you call this setup.

It’s always comical when someone introduces themselves as a different name than their name tag lol. Get a Velcro name tag for videos!

Is 346 in service or not? And if not, then why?

how do you know?

You asked for it how do you know hyce

So it's not a governor?!... and or isn't there a governor somewhere to mitigate runaway? Don't worry I won't do that, I can't play with LOCOS they wont let me! (I ASKED).

how do you know hyce