[TC10] Pneumatic Locomotive

[The_Brown_Hornet]

Greetings All,

Apologies for being very late to the party, but the TC10 pneumatic competition brings together my favourite parts of what technic is all about and I really wanted to contribute.

A number of years ago I had to good fortune to come across a big bunch of pneumatic parts. Having worked on all sorts of pneumatic based MOC's my beloved wife put out the challenge to build her a steam train thus beginning a five year odyssey before finally arriving at the model I present to you all today.

Creating a genuinely functioning Lego Pneumatic Locomotive has been a real challenge, searching the internet brings up very few examples.  Creating a valve assembly that is both functional and reasonably robust within the confines of lego has proven quite the challenge.  Rather than completely reinventing the wheel, I have based my model on a simplified version of Walschaerts Valve Gear that was used on many steam trains through history.  I set out at the start of this competition to make a fully reversible valve gear as per the real thing but it proved too much of a challenge at this stage - see how the next few years pans out.

The Model:

• Classic 4-8-2 locomotive configuration using 62.4 tyres for driving wheels
• old style clear pneumatic cylinders for drive
• old style pneumatic valves
• Six manually operated pneumatic pumps - this thing need lots of air.

All parts use are original, unmodified, genuine Lego items.  The reason I have used "old" style valves is that they are the ones that I could find with minimal resistance, allowing the whole system to function property.

Starting with the final result for those of us into instant gratification;  This is the final interpretation of my pneumatic locomotive.  I will, however make you scroll further for the video.

The key to the success of this model is has been in effectively copying the principals behind the walschaerts valve system where the throw of the valves is delayed by the eccentric on the main driving wheel.  It is only once the piston ( pneumatic cylinder) has reached the end of it's stroke that the valve is thrown in the opposite direction to push it back the other way.  The two valve trains on either side of the loco are offset by 90 degrees so that they "help" each other past the dead spot at the limits of each cylinder's stroke.

No matter what I tried, the fundamental principal was "More Steam Coalmam!'  In manual form, 6 pumps are required to provide adequate air supply.  Four air reservoirs for the testing phase and three in the final model smooth the pulses from six manual pumps to a point that we have reasonably smooth motion.

 

Lucky last, a brief video showing how it works.

I'll try to post an ldraw of the basic mechanism in the not too distant future but instructions are well outside my current skill set.

If you've got this far, thanks very much for taking the time, I hope it's proven interesting.

The Brown Hornet

Edited November 4, 2016 by The_Brown_Hornet
Resize images according to guidelines

[efferman]

Works pretty fine. Thumbs up

[Jeroen Ottens]

Excellent entry. I love the fact that you replicated the real steamlocomotive mechanism for this.

And it shows that those trains needed railtracks to keep them straight

[JJ2]

Really cool, I like the way you remade the mechanism.

[Josephiah]

Wow, amazed that you managed to get that mechanism to run so fast and smoothly. 

[Appie]

Very sweet train. Besides the realistic mechanism, I like where you placed the air tanks. Great work

[proran]

Finally, someone have done it legally!!! Congratulations! I have tried to do it some time ago, but completely failed. The main problems were the high resistance of the valves (I used the new ones) and high required stiffness of the frame. If the cylinders are not perfectly synchronized they will twist the frame into a knot. Congratulations on your achievement. It is a Technic marvel!

[jono rocky]

Seriously impressed, getting the valve and running gear to work realistically and that fast is a feat in itself. Well done.

[WvG_853]

I have followed your progress with interest and am impressed with the result. Nice touch to show the locomotive next to a real rail track.

Good luck!

[The_Brown_Hornet]

Thank you all for your generous comments, I really appreciate it.

WvG_853, just for clarity I think you may be referring to another Pneumatic Locomotive created by Samer for this same TC-10 competition.

He / She has taken a slightly different approach and I too have been following progress with interest.

I really like the use of the motorcycle wheels for driving wheels, it give a opportunity for a very large scale model.  Alas, at this point, I have only two motorcycle wheels and I really wanted to make a 4-8-2 configuration.

Regards

TBH

[WvG_853]

You are right, I mixed up the projects. Still impressed with the result! 

Edited October 31, 2016 by WvG_853
Typo

[grum64]

Very impressive entry.

[bonox]

Impressive. On Jeroen's comment about needing tracks, you see the real ones yawing side to side in the tracks like this thing (but this one is obviously unconstrained).

[Seasider]

Totally love this.

I'm now interested in trying to build my own "steam" train. Any suggestions of where to start ? So I can start planning.

 

[Jim]

Hi,

Nice entry!

Please make sure the images you post on EB are max 1024 wide. It's stated in the site guidelines.

Can you change the images to smaller version? You are using Bricksafe, so you can easily link to a smaller version  by adding "/1024x768.jpg" at the end.

[The_Brown_Hornet]

Hi Seasider,

I'm really glad you like the model and am flattered that you want to build your own.  

The real secret to getting this to work properly is to find pneumatic switches that don't have too much resistance so that the mechanism can operate with relative ease.  That's the entire reason  behind using the old style switches. I have a few new style valves that are all very stiff and, in fact, out of about twenty old valves i have, only two or three had suitably low resistance.  I don't know if you can artificially wear them out to make them move more freely?  Silicon lubricant may help.  That's a long winded way of saying that you need to find two pneumatic switches that move freely.

I used the old style pneumatic cylinders because I only have two clear ones in my collection and I like to watch the pistons moving back and forth.  I don't think it will make any functional difference whichever type of cylinders you use.

This thing required a lot of air to operate effectively.  As shown in the pictures and video I use 6 manual pumps.  I did try to use motorised small pumps but with even with 6 small pumps it still didn't provide enough air to go very well.  Take this advice with a grain of salt as ti was many years ago that I tried the motorised compressor.

I did mention that I was planning to provide an ldraw file of the basic mechanism behind the model and intend to make good on that promise.  At the moment I am away from home for work so don't have access to my Lego to create the digital model so please bear with me until i get the time to complete and post it.  If you can wait for the ldraw model I expect it will be able to answer many potential questions as to how it all functions.

Regards

TBH

[The_Brown_Hornet]

52 minutes ago, Jim said:

Hi,

Nice entry!

Please make sure the images you post on EB are max 1024 wide. It's stated in the site guidelines.

Can you change the images to smaller version? You are using Bricksafe, so you can easily link to a smaller version  by adding "/1024x768.jpg" at the end.

HI Jim,

Thanks for the compliment, appreciate it.

Apologies if I've posted incorrectly, I have every intention to operate within the site guidelines.

I will make corrections as soon as I can work out how.

Regards

TBH

[Jim]

Cool! No worries  

I have fixed them for you  

[The_Brown_Hornet]

Hi Jim,

Thanks very much.  I have worked out how to bring in correctly sized links in the first place so hopefully I can be compliant first time in the future.

Regards

TBH

[Seasider]

Thanks for all the info Hornet, something for me to try in the new year I think with a brick link purchase of a few air tanks, pumps and some old switches

 

i need to get on with my planned mods to the CLAAS first

[Technic Train Man]

This pneumatic train is really fantastic! I never took the time to find out how a steam locomotive works and now I know!

It has been almost 5.5 years since the last post here so I hope The Brown Hornet still checks this site. I see he was here 17 days ago so I assume so!

I can't send him a PM yet I think because I am new at Eurobricks.

I would really like to try to build a pneumatic locomotive like this. I have built a whole bunch of Technic Trains but they are all a bit smaller than this pneumatic locomotive.

So I was wondering if the "new" 1x11 Pneumatic Cylinder could work. It needs less air and less space so if it can work I will try it out. Is it bad it can extend more or maybe better?

And I would really like to build this model in Stud.io and The Brown Hornet can get the file (and instructions) to upload on Rebrickable or whatever he likes. I have been building so many technic trains in Stud.io lately it should only take a couple days. I just need a bunch of photos to build it first.

I've got a 9 stud wide Technic Train track made completely of Technic beams running through my living room. The track is around 15 meters long and also has switch points made completely of Technic beams.

It would be great if we could build a smooth running pneumatic locomotive that rolls on a technic beam track! And it would be great if the 1x11 Pneumatic Cylinder could work because then I can build a train car with an air compressor with a lot of air pumps (12x?).

A whole train car can be the air compressor!

What do you think?

 

 

 

 

 

My Technic Trains: 

 

[allanp]

@Technic Train Man your choice of cylinder will probably depend on a few things, like desired speed (shorter strokes are faster), desired torque (longer stroke for more torque), available air supply (large diameter cylinders if you have enough air) and what modifications, if any, you intend to do to the valves. The standard unmodified valves are quite stiff and so they probably won't work well with 1 stud diameter pneumatics.

[gyenesvi]

14 hours ago, Technic Train Man said:

My Technic Trains: 

Wow I did not even know people would be building trains out of technic, including the rails, you have a pretty cool station complex there! I like the way they look and there are lots of cool functions to be motorized for sure. Just out of curiosity, what triggers that sideways tipping mechanism? It seems like something automated somehow?

[Technic Train Man]

2 hours ago, gyenesvi said:

what triggers that sideways tipping mechanism?

Hi, I thought my video was clear enough but it's simpler than you think. On the top of the bucket there are a couple axles sticking out to the side. They slide over the rigid hoses I put next to the track. One axle will be sliding up and then the other side will push the axle down till the bucket is completely down. It's funny I made the first version I while ago and I can't remember how I came to this design haha.

More info:  https://rebrickable.com/mocs/MOC-102141/Technic TRAIN Man/technic-train-tipper-dump-car/#details

[Technic Train Man]

@allanp

Hi, thanks for the reply!

I don't mind to modify a couple 1x11L cylinders (and switches) to have a great pneumatic train. I think I will also take a marker pen and make them black. That will look pretty nice!

Yesterday evening I could not resist and start building the pneumatic train in Stud.io. I think I already have most of the mechanism, I just need to connect it to a chassis.

I will probably first try to build this pneumatic train with the bigger cylinders to know exactly what it takes to make it work. And then try to make it with the 1x11 cylinders.

It seems like the stroke length can be limited by blocking the beginning/end.

I have not modified pneumatics but I have seen videos and when you drill the holes bigger the air flow increases enormously. So with that in mind I think the 1x11 cylinders could work.

I hope The Brown Hornet will give some advice and also some photos so I can finish his model in Stud.io.

It already looks cool!