Pneumatics General Discussion

[CrankyCraig]

1 hour ago, howitzer said:

BTW, I wonder if anyone has remodeled 42100 to work with pneumatics in place of linear actuators?

In all fairness, from what I've seen, 42100 does seem very good from a functional perspective. I don't own it (yet) but I can't see an advantage swapping over to pneumatics. However, at that size and weight, I can see a whole bunch of challenges that would take someone far more experienced than myself to overcome.

51 minutes ago, pleegwat said:

8868B is possibly my favourite of the sets I own.

8868 was such an incredible set for it's time. At 8 years old, that's where my love for Technic began (and remained for a long time). I built those vehicles soooo many times. I'd build it, and the figures would briefly get to drive it about and use the functions, but then it would almost always be involved in some kind of road traffic accident with another Technic set. It used to get launched into walls / off ramps / down stairs, with a resulting explosion of pieces each time. I'd recover and briefly examine the crumpled wreckage, and then immediately set to work restoring it. That set in my hands took some punishment.

[davidmull]

Iv modded my unimog with the new longer cylinders. Problem is the pressure is dropping and the arm finds it hard stay up. My question is the newer pump blue in the arocs is it’s any better than the grey pump in the unimog 

[9v system]

5 hours ago, davidmull said:

Iv modded my unimog with the new longer cylinders. Problem is the pressure is dropping and the arm finds it hard stay up. My question is the newer pump blue in the arocs is it’s any better than the grey pump in the unimog 

i found that the blue pump has the extra plastic at the base to stop it from cracking, the older ones have issues with splitting at the base causing loss of pressure

[P McCatty]

6 hours ago, davidmull said:

Iv modded my unimog with the new longer cylinders. Problem is the pressure is dropping and the arm finds it hard stay up. My question is the newer pump blue in the arocs is it’s any better than the grey pump in the unimog 

1. It may also be a good idea to check the system for leaks. Sometimes the hoses (especially the older, tighter ones) can split near the connection points with repeated assembly & disassembly.

2. In your modification, did you perhaps reduce the mechanical advantage of the pistons somehow? That could be a contributor as well. With the increased range I'd find this unlikely though.

3. With a bit of trial & error, you could mount shock absorbers in the linkage to dampen the downward movement of the crane arm. This helps it to stay elevated even with a loss of pressure & as an added bonus, reduces the "crashing boom" effect.

[Saberwing40k]

11 hours ago, davidmull said:

Iv modded my unimog with the new longer cylinders. Problem is the pressure is dropping and the arm finds it hard stay up. My question is the newer pump blue in the arocs is it’s any better than the grey pump in the unimog 

So, what is happening here?

If you are raising the arm, and keeping it posed in the extended position for extended lengths of time, it will droop and not stay up. This is a problem with all pneumatic cylinders, they will bleed down if not pressurized.

 

[howitzer]

1 hour ago, Saberwing40k said:

So, what is happening here?

If you are raising the arm, and keeping it posed in the extended position for extended lengths of time, it will droop and not stay up. This is a problem with all pneumatic cylinders, they will bleed down if not pressurized.

 

It should not happen immediately though, at least if the arm isn't heavily loaded. I've had the 42128 sitting on my shelf with boom up for months now, with no movement downwards, but it doesn't have much load either.

Anyway, I understand that the first release of Arocs had also the pump with cracking base, so it would cause leaks. I have two of those, and it's really annoying though I haven't bothered to buy new ones either...

[Julsonheimer]

Hi, I have a question about the old yellow lego pneumatic pump. Is it normal that the black part that you push down wobbles like this?

Edited March 31, 2023 by Julsonheimer

[allanp]

51 minutes ago, Julsonheimer said:

Hi, I have a question about the old yellow lego pneumatic pump. Is it normal that the black part that you push down wobbles like this?

 

It is quite wobbly, not as rigid as the normal cylinders because there is no top seal.

[Julsonheimer]

hello i have another question about this pump if i rotate the black part, it sometimes stopes working and if i turn it again it works fine again. Is this normal?

 

[SAM1626]

Does anybody else absolutely love lego Pneumatics (LPE's, simple functions, etc.)? I would love for this topic to just be a thread where we can share creations made with pneumatics, hopefully I am not the only one.

[amorti]

I loved pneumatics as a kid, because I had the big black truck with the compressor.

But somehow these days I find actuators better, as you can actually get accuracy with them.

I happened across this set NIB at the local science museum and bought it on a whim, but now don't know what I'd do with it.

Anyone in the EU interested in buying it?

https://www.bricklink.com/v2/catalog/catalogitem.page?S=9641-1#T=S&O={"iconly":0}

[SAM1626]

2 minutes ago, amorti said:

I loved pneumatics as a kid, because I had the big black truck with the compressor.

 

set number?

[amorti]

Just now, SAM1626 said:

set number?

8868.

But to be clear it's 9641 that I have NIB.

[SAM1626]

 

2 minutes ago, amorti said:

8868.

Do you still have it?

[amorti]

3 minutes ago, SAM1626 said:

 

Do you still have it?

No. There was a time in my dark ages when I really needed that ≈£80 and it had to go.

[SAM1626]

1 minute ago, amorti said:

it had to go.

this is sad but I too have had to sell legos because I needed the money (for more legos).

[pekka111]

21 minutes ago, amorti said:

I loved pneumatics as a kid, because I had the big black truck with the compressor.

But somehow these days I find actuators better, as you can actually get accuracy with them.

I happened across this set NIB at the local science museum and bought it on a whim, but now don't know what I'd do with it.

Anyone in the EU interested in buying it?

https://www.bricklink.com/v2/catalog/catalogitem.page?S=9641-1#T=S&O={"iconly":0}

Sorry what is a compressor?

This is an interestic topic. I'm wondering in what kind of cases you have to use pneumatics instead of gears, axels and actuators.

Edited January 31 by pekka111

[SAM1626]

8 minutes ago, pekka111 said:

Sorry what is a compressor?

Do you know what a air compressor is? if so basically just this in lego technic with obvious slight differences but same compressed air idea.

 

11 minutes ago, pekka111 said:

This is an interestic topic. I'm wondering in what kind of cases you have to use pneumatics instead of gears, axels and actuators.

Usually instead of using actuators for excavators arms or dump trailers we use pneumatics because they operate faster than actuators and are cooler

[pekka111]

30 minutes ago, SAM1626 said:

Do you know what a air compressor is? if so basically just this in lego technic with obvious slight differences but same compressed air idea.

 

Usually instead of using actuators for excavators arms or dump trailers we use pneumatics because they operate faster than actuators and are cooler

Is the compressor some Lego part or something that you build?

[aeh5040]

Yes pneumatics are good. In principle one can use it for arbitrary logic or calculation! One long term goal is a fully pneumatic Babbage difference engine, but using binary rather than decimal.

One disadvantage is that constant running tends to dry out the cylinders, so it is not so good for shows.

Case in point:

https://youtu.be/qsW5xmd9XCY

Edited January 31 by aeh5040

[amorti]

2 minutes ago, pekka111 said:

Is the compressor some Lego part or something that you build?

In that model there was a battery pack and motor, driving a pneumatic cylinder to put air into the system. If you want to see the idea, you can (probably?) download the instructions at lego.com.

Or otherwise, they used a similar system with more modern parts on the Mercedes Arocs, pretty sure you can still get the instructions for that one.

[SAM1626]

4 minutes ago, aeh5040 said:

Yes pneumatics are good. In principle one can use it for arbitrary logic or calculation! One long term goal is a fully pneumatic Babbage difference engine, but using binary rather than decimal.

One disadvantage is that constant running tends to dry out the cylinders, so it is not so good for shows.

Case in point:

https://youtu.be/qsW5xmd9XCY

this is a cool idea

5 minutes ago, pekka111 said:

Is the compressor some Lego part or something that you build?

you have to build compressors as they are multiple pieces here is a link to a image https://www.worthpoint.com/worthopedia/lego-technic-large-pneumatic-1864768758 ignore everything but the image

instructions for a compressor for an example https://www.daslhub.org/unlv/wiki/doku.php?id=tutorial_iv

[SAM1626]

pneumatics in trains is a good idea but not always very efficient but I'm sure train moderator JopieK could tell us more for our train fans

[pekka111]

1 hour ago, SAM1626 said:

this is a cool idea

you have to build compressors as they are multiple pieces here is a link to a image https://www.worthpoint.com/worthopedia/lego-technic-large-pneumatic-1864768758 ignore everything but the image

instructions for a compressor for an example https://www.daslhub.org/unlv/wiki/doku.php?id=tutorial_iv

Thanks (for amorti too)! I have built that without the tank, just didn't connect the dots.

Edited January 31 by pekka111

[SAM1626]

Glad we could help