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alfredboyer

[MOC] Pneumatic Steam Locomotive - scale 1:25

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Posted (edited)

Hello Lego train fans,

(I repost here the work I have done on a pneumatic locomotive. I really don't know where to post since my MOC belongs to Technic category and Train category. So I post it here too. Of course here maybe we can talk more about the design and reproduction of the details of the locomotive. If this other post is too much, I am sorry that I posted in two places (and moderators could remove it), but I think it's understandable why I did this. Anyways !)

I am glad to introduce you my last big project : a pneumatic steam locomotive !

I think it's one of the firsts pneumatic locomotives, using only Lego parts. I love trains as much as you do on this forum probably, so I hope some steam lovers will enjoy the model ;) 

The model is based on a Mikado type locomotive, from the mid 20th century. It especially copy the design of 141R french locomotives (even they were apparently built in USA, for France).

First of all, the YouTube video and some photos:

txpc.jpg

exlt.jpg

73lb.jpg

The idea with this model is to replace the steam of a real Locomotive by compressed air, and this for as much functions as possible.

Here are the main functions :

Movement of the train :

Using 4 pistons, 2 on the sides, and 2 inside, the train can move forward. It works like a classic LPE, with 2 pistons shifted 90° from the others. 4 pistons consume a lot of air, but they guarantee enough power to move the whole train. 

6p5u.png

To make the rotation smooth, a free wheel is hidden inside the boiler part of the locomotive. Its rotation is 25 times faster than the wheels of the train (40t/8t x2).

The train isn't moving very fast because the pneumatic elements aren't modified. However, it's fast enough to make it interesting to look at the connecting rods and wheels moving.

The breaks :

On a real locomotive, compressed air is produced by a compressor (powered by steam) and is used to press some brake shoes against the wheels.

Here, the same technique is used : a small piston is filled with compressed air, and thanks to some rods, brakes shoes are pressed against the wheels. 

g4ik.png

j4qo.png

It's cool but...it's not enough. Plastic against plastic isn't very efficient to stop the train's movement. Therefore, another rod is connected to the brake system and press another brake shoe against the free wheel. Because its rotation is faster (and therefore, with a low torque), it's is way easier to stop it.

The Whistle :

A system that I love in this locomotive is the whistle. Currently there isn't any whistle produced by Lego that could be used in the locomotive, so I had to think a little for finding something working. I can give you more details if you want but I used some lego parts that are empty inside and have a small aperture. By blowing air on these parts, we can produce a noise that is a little similar to a whistle noise. 

This whistle is activated by a switch in the cabin.

The Cabin :

m5ja.png

Nothing much to say except that in contains 3 switches for the 3 main functions (whistle, wheel movement and brakes). There is also a pressure gauge showing the pressure coming from pumps. The train moves with a minimum of 1 bar. A 2-2.5 bars, the movement is faster.

The air supply :

There are several possibilities for the train : we can directly pump with Lego pumps, or store the air into 6 to 8 airtanks or produce the air with Lego motors and small pumps. For instance I use 4 pumps side by side, linked to some air tanks, but I don't what the final model should work. Maybe some motors and pumps could be cool ?

The design :

The hard part was to make the boiler of the locomotive. It's a little hard to make cylinders with Lego technic parts but, with flex axles passing through Technic beams, I managed to make something satisfying. 

Some details are visible on the locomotive, I tried to make it look a little crowded like a real locomotive with fake air/sand tanks, fake compressors and mechanical elements. It's probably possible to make it look better, but for instance I am happy with it.

The rails are "homemade" with Lego bricks. The locomotive is too big of course to work on Lego railtracks. The wheels aren't perfectly flat so the train is "blocked" in position inside the rails. Therefore, the train can move foward cur cannot go out of the railtracks (which is great for a train).

Finally, as a bonus functions, there are some bumpers at the front and back of the locomotive to imitate the real bumpers used to absorb small chocs on a Locomotive.

That's it for now, I hope the model is interesting to you and if that's the case, don't hesitate to support it on Lego Ideas ! Click here to support on Lego Ideas

If you have any question or comment, please reply to the post, I'll be glad to discuss with you !

Edited by alfredboyer

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EPIC! 

Love it.

The only thing that's missing is flanges on the wheels :)

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Wow, wow, wow.

 

This is the best compressed-air locomotive I've ever seen.   Some amazing use on technic for the loco.  The boiler is done perfectly so it looks round.  The WORKING valve gear is perfect but would look better 3d printed.  One thing, it would be fun to see the thing running on lego tracks around someone's yard pulling some kids on wagons.  

 

Internally how does it work?

 

Coal Fired

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4 hours ago, Coal Fired Bricks said:

One thing, it would be fun to see the thing running on lego tracks around someone's yard pulling some kids on wagons.  

 

Internally how does it work?

wow that's a dangerous Idea ! Not for the kids, but for my Legos haha. Seriously I think I can pull a mouse or a guinea pig, maybe a kitten but no more.

Internally it works like a classic Lego Pneumatic Engine, like this

2cylinderengine.gif (gif by Nico71)

A serie of four 36t gears connects the piston and wheels together, and transmit the power to the free wheel (after a couple of 40t/8t). Only the 4 front wheels are linked by gears, the 4 others are free. I can give you some more views if you like, I have some 3D models made for the loco.

Thank you guys for the comments, it's well apreciated :) 

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Wow, that's an impressive beast! The colours made me think German but there are very few of those with 4 driver axles.

A friend of mine in the Netherlands built some pneumatic steam engines a long time ago but they were based on American designs.

http://www.brickshelf.com/cgi-bin/gallery.cgi?m=rekok

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Wow, this is amazing!  I think this might be the first time I've ever seen a model locomotive of any sort, let alone LEGO with functioning air brakes!  This is some top-notch work!

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I don't care if I am the third person to say it in this thread, but wow, that is amazing! Just shows what is possible in 12 wide (grin). Incredible work you've done there

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I'll be the fourth then to say what you've created is amazing. How long will it run on a 2.5 bar air charge?

Not sure the brakes are needed but as a retired designer of diesel loco brake rigging I really like how you added that functionality.

Will your next iteration to be adding a real steam boiler?

Dave

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Very nice train indeed, otherwise I would feature it but it was already featured in Technic of course.

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Posted (edited)

Thank you everybody for being so supportive ! I am happy you like the design :)

I've been told that it's not the best to post my MOC presentation in two different eurobrick's forum. So if you want more explainations etc please go to the Technic section ! :

Click here to go to the main topic page

20 hours ago, bogieman said:

How long will it run on a 2.5 bar air charge?

Not sure the brakes are needed but as a retired designer of diesel loco brake rigging I really like how you added that functionality.

Will your next iteration to be adding a real steam boiler?

On 2.5 bars it should go for about 2-3 meters far on full air tanks, depending on which speed you choose. It's not much so that's why people suggested to add a little lego compressor in the tender with a battery box. I think that's a nice solution to make it go as far as possible :)

For a real steam boiler...I am staying on a only lego parts design for now, but damn it would be awesome to see this machine with steam all around !

Edited by alfredboyer

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I assume running on air, not steam? Steam at any sort of pressure will be hotter than what ABS can cope with...

If you don't want the noise of a compressor maybe you can add a tanker car behind that hides a 2L PET bottle?

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21 minutes ago, Duq said:

I assume running on air, not steam? Steam at any sort of pressure will be hotter than what ABS can cope with...

If you don't want the noise of a compressor maybe you can add a tanker car behind that hides a 2L PET bottle?

Yeah of course of steam, no lego can survive.

The compressor will make some noise for sure, and it may even hide the "tch tch" we can hear from the pistons and switches. But I want to keep this project with only Lego parts for instance, even if, yeah, a 2L would totally give enough air for a while. The other solution is to put something like... 25 Lego air tanks, but then it will start to be hell of expensive

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1 hour ago, alfredboyer said:

For a real steam boiler...I am staying on a only lego parts design for now, but damn it would be awesome to see this machine with steam all around !

While it isn't pure lego, lego live steam has been done.

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