Pneumatics General Discussion

[Epic Technic]

Sadly all of the 24t-20t-24t; 20t-24t-20t; 8t-36t-8t; and 36t-8t-36t just slip when I try them. Though an idea just popped up in my mind, what if I had a 24t-20t-24t then a chain around it. Could it better distribute the forces? But first I need to find a few more chain links in my big box of LEGOs (it might take some time ).

[Blakbird]

.............things can also be much more complicated...

You mean like this?

[MSc Shobaki]

Sadly all of the 24t-20t-24t; 20t-24t-20t; 8t-36t-8t; and 36t-8t-36t just slip when I try them. Though an idea just popped up in my mind, what if I had a 24t-20t-24t then a chain around it. Could it better distribute the forces? But first I need to find a few more chain links in my big box of LEGOs (it might take some time ).

Hmm, the only advise I have is to pack in the gears within the cylinder block. Integrate them instead of having them exploited. With this, the gears are restricted from slipping outside the block.

[Epic Technic]

Hmm, the only advise I have is to pack in the gears within the cylinder block. Integrate them instead of having them exploited. With this, the gears are restricted from slipping outside the block.

No space inside but I could easily build an extra front panel and it would do the same. Thanks!

[MSc Shobaki]

No probs! Looking forward to see more :)

[aeh5040]

You mean like this?

Indeed!

[Milan]

What about 2 or 3 rows of chains?

[aeh5040]

Sadly all of the 24t-20t-24t; 20t-24t-20t; 8t-36t-8t; and 36t-8t-36t just slip when I try them. Though an idea just popped up in my mind, what if I had a 24t-20t-24t then a chain around it. Could it better distribute the forces? But first I need to find a few more chain links in my big box of LEGOs (it might take some time ).

That's probably because your connections are not strong enough. The LBG right-angle connectors do not make for rigid connections, because their pins are frictionless. You need some cross-bracing liftarms. For high torque situations it's also a good idea to brace the gears on both sides of their axles. I think a chain would be in danger of rubbing on the 20t, and it would not solve the underlying problem.

[2LegoOrNot2Lego...]

You mean like this?

Pure madness, but genius though!!!

Edited November 14, 2015 by 2LegoOrNot2Lego...

[Epic Technic]

What about 2 or 3 rows of chains?

I dont have that many chains :(

That's probably because your connections are not strong enough. The LBG right-angle connectors do not make for rigid connections, because their pins are frictionless. You need some cross-bracing liftarms. For high torque situations it's also a good idea to brace the gears on both sides of their axles. I think a chain would be in danger of rubbing on the 20t, and it would not solve the underlying problem.

I know, I am going to make a front 'plate thingy' for it then try.

[Epic Technic]

It finally worked with a 24t-20t-24t gear combination and a 'front panel thing'. The next issue is that even my four LEGO hand pumps aren't enough to get it rotating at a decent rpm. I need to find a method to get high air pressures, however, I do not have access to an air compressor, nor dry ice.

Any help is appreciated

[MSc Shobaki]

Go to your local hardware store and ask for compressed gas can. Its basically hard-pressured air in a spray can with a tube (nozzle). The tube fits tightly inside the lego hose.

With the pressure from the can, you'd get 5-6 bars of air pressure resulting in high rpm if you have modified pneumatic parts.

My Inline-3 made 1800 rpm on a spray can.

[aeh5040]

Pure madness, but genius though!!!

It's a pity no-one seems to be working in complex self-actuating pneumatic circuits these days. There was quite a lot of activity in this a few years ago, but the art seems to have almost died out. Check out:

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

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=82736

http://www.brickshelf.com/cgi-bin/gallery.cgi?m=sigurd18

[allanp]

Have you considered using 1 liter fizzy pop bottles and a foot pump?

[Refy L.S.]

Hey, so Ive been looking at Technic recently and I've toyed with most stuff now, but not really pneumatics. Which sets are the ones considered best to start one off with the system? Preferably ones that arent to pricey.

[Captainowie]

Hey, so Ive been looking at Technic recently and I've toyed with most stuff now, but not really pneumatics. Which sets are the ones considered best to start one off with the system? Preferably ones that arent to pricey.

I don't like your chances too much - all the modern pneumatics comes with large/flagship sets, and all the old pneumatics are from ... well ... old sets, where part quality can vary considerably. Your best bet if you don't want to pay too much is to buy a couple of parts individually from Bricklink.

Owen.

[Epic Technic]

Go to your local hardware store and ask for compressed gas can. Its basically hard-pressured air in a spray can with a tube (nozzle). The tube fits tightly inside the lego hose.

With the pressure from the can, you'd get 5-6 bars of air pressure resulting in high rpm if you have modified pneumatic parts.

My Inline-3 made 1800 rpm on a spray can.

That's actually a very good idea, thanks. It gives me the idea that the can could be built inside a car and there would be a throttle system to let air out. Was your LPE modified, and did it use the new or old style switches ? How long did one spray can last you?

Have you considered using 1 liter fizzy pop bottles and a foot pump?

I have tried but it doesn't get at a very high pressure, nor does it run for very long.

Hey, so Ive been looking at Technic recently and I've toyed with most stuff now, but not really pneumatics. Which sets are the ones considered best to start one off with the system? Preferably ones that arent to pricey.

If you want a bunch of pneumatics, buy the 8455 from bricklink, though it does cost around $140.

[allanp]

Really? A foot pump usually gets to over 100psi, not that I would recommend filling 1 liter pop bottles to that pressure of course

[Epic Technic]

Really? A foot pump usually gets to over 100psi, not that I would recommend filling 1 liter pop bottles to that pressure of course

Well, don't have a foot pump, I only have a handheld bicycle pump that definitely does not get to 100 psi very easily.

[JJ2]

You mean like this?

*snip*

What is that A walker?

[MSc Shobaki]

That's actually a very good idea, thanks. It gives me the idea that the can could be built inside a car and there would be a throttle system to let air out. Was your LPE modified, and did it use the new or old style switches ? How long did one spray can last you?

I have tried but it doesn't get at a very high pressure, nor does it run for very long.

If you want a bunch of pneumatics, buy the 8455 from bricklink, though it does cost around $140.

I could run it easily for 7 minutes in total minimum on one spray can, full throttle. But it gets really cold after 30-45 seconds so you can only run it for a minute before you need to take a break. Hmm one bottle goes for 10€ maybe, at least here in Stockholm.

I have actually two inline-3s, one uses the old switches and the other one uses the new ones.

All switches and cylinders are modified and re-glued. However, if you need to modify the new ones you need to cut off the round pin connectors and then glue two technic bricks with holes on the sides of the switch :)

It works like a charm and the connectors that you cut off can be used like new ones that appears in 42043 for example :)

[GTRulez]

Guys have you tried a non lego compressor yet?

I'm using a small single cylinder electric compressor designed for Airbrush pistols. modified the hose a bit so it will accept a standard Lego hose.

it lets you adjust the air pressure so you can always find a good balance between speed and power. it can generate up to 4 bar of air pressure but you wont need that much (the hoses will pop off the ports anyway at that amount of pressure) you can adjust it anywhere in between 0.1 to 4 bar

My biggest pneumatic MOC right now is a big material handler on top of a crane carrier chassis (42009). it uses 14 big pneumatic cylinders in the boom and its grab. its way to big to operate at a reasonable speed with the lego pumps. but with this small compressor its very fun to play around with, just hook one hose up, start the compressor and you have an endless supply of air! you can find them new for around 50-100 euro's but i found mine for just 20 euro's used but its still in perfect condition :) great for excavators and such, i guess it would be fine for a pneumatic engine aswell. only downside of it is that you cant really build it inside of a model.

Edited November 17, 2015 by GTRulez

[A Gallifreyan Cat]

Does anyone know of any good designs for pneumatic engines with the new (v2) cylinders, those that came in the Mercedes Arocs? And preferably one that does not involve modifying pieces.

[MSc Shobaki]

Does anyone know of any good designs for pneumatic engines with the new (v2) cylinders, those that came in the Mercedes Arocs? And preferably one that does not involve modifying pieces.

The only way I see it with the new v2 cylinders is that they are too long to be of use in an LPE. 11 studs retracted, some 17-18 studs fully extended, that is very long.

You could build a 4-cylinder engine if you have four of those 2x11 studs, but I dont think you'd find a use for it in a car. I think that an engine in that scale would be suited for a car in scale 1:5, you won't find proper tires in LEGO for that scale. Unless you buy third party tires.

With unmodified parts, you would not be able to get high rpms. The engine would move very slowly and inefficient.

[A Gallifreyan Cat]

Are there any pneumatic engines that run at a reasonable rpm without modified parts?