Brick Technology Hydraulic Lego Excavator

[Bartybum]

Could you not just have a T-junction along the top end of the hydraulic circuit that holds a small air pocket?

Edited August 25, 2023 by Bartybum

[2GodBDGlory]

On 8/23/2023 at 5:27 PM, gyenesvi said:

Hmm, that is true. It could be done with valves though, and one valve could be used for pressurizing two separate circles, son only half the amount of valves needed. Or a small pump for each circle could also do.

@2GodBDGlory, since you are already experimenting with it, could you try how a single circle works with pressurized air vs non-pressurized air?

Alright, it took me a bit longer than I had hoped, but I had a chance to try that out tonight, and it honestly works pretty good! The higher-compression in the air definitely works more like a liquid, and doesn't allow for much extra compression, giving it much more force than the version with just atmospheric pressure, which was limited by a low amount of air in the system to work with.

I think the main thing to worry about at this point would be the annoyingness of having to re-pump it regularly, but I'll plan on trying some more things, and maybe making a little video on it

On 8/25/2023 at 6:02 AM, Bartybum said:

Could you not just have a T-junction along the top end of the hydraulic circuit that holds a small air pocket?

Hmm, I'm not quite sure what you mean with that

[Bartybum]

1 hour ago, 2GodBDGlory said:

Hmm, I'm not quite sure what you mean with that

A little bleed line that branches off the main circuit, which houses a small air pocket that can expand and contract. That being said, upon second thought my solution wouldn't really make any difference versus just having air bubbles in the line

[gyenesvi]

4 hours ago, 2GodBDGlory said:

Alright, it took me a bit longer than I had hoped, but I had a chance to try that out tonight, and it honestly works pretty good! The higher-compression in the air definitely works more like a liquid, and doesn't allow for much extra compression, giving it much more force than the version with just atmospheric pressure, which was limited by a low amount of air in the system to work with.

Thanks a lot for testing this, that sounds pretty promising!

Did you test it built into something simple to get closer to how it would begave in real conditions?

4 hours ago, 2GodBDGlory said:

I think the main thing to worry about at this point would be the annoyingness of having to re-pump it regularly, but I'll plan on trying some more things, and maybe making a little video on it

I am quite confident this would not be a problem. As I wrote in my previous post, simple valves (which are present in hand pumps) could be installed in each circuit, and then one pump would be needed for pressurizing all circuits. If such a pump would be built into each model, then it would at worst mean giving it a few pumpings before a play session. Still much better than pumping through the whole play.

Did you experience leaking during pkaying with it? Did you need to re-pressurize it? Looking forward to the video!

I wonder how the valve is implemented inside the hand pump, and whether a separate peristaltic pump piece could be printed including outlets for attaching hoses (whether 3d printing is precise enough for that, sounds a bit ambitious)..

[m2fel]

To pressurize two separate circuits you can use one valve. First pump up circuit 1, then circuit 2 and then just close it :)

[gyenesvi]

9 hours ago, m2fel said:

To pressurize two separate circuits you can use one valve. First pump up circuit 1, then circuit 2 and then just close it :)

Yes, this is what I wrote as a first idea, which is possible with today's parts. But the system could be simpler with proper parts, a simple valve that lets air through in one direction only (something like the manual pump must contain) would be sufficient in each circle, no switching required.

[2GodBDGlory]

2 hours ago, gyenesvi said:

Yes, this is what I wrote as a first idea, which is possible with today's parts. But the system could be simpler with proper parts, a simple valve that lets air through in one direction only (something like the manual pump must contain) would be sufficient in each circle, no switching required.

Such a valve does exist, in the classic distribution block part from the '80s! It's what I used in my video, which is now up and unlisted on YouTube!

In the video (which is rather rough), I test lifting the same arm under load three different ways, with a non-pressurized peristaltic system, a pressurized peristaltic system, and a traditional compressor. My conclusions are that pre-pressurizing the system makes a huge difference in responsiveness, and that the peristaltic compressor doesn't move the cylinder as fast as the basic compressor I used. The peristaltic system does have the edge in controllability, though, since it doesn't require switches, and can be run off of a single motor and controlled by changing direction. Plus, it allows for much more controlled retraction of the cylinder under weight.

Also, if anyone is just hopping onto the thread here, this pump design is not mine! I copied it off of Brick Technology on YouTube!

Edited August 27, 2023 by 2GodBDGlory