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?