[Loughla]

>Or you somehow compact it between two pistons that can provide lots of force and not be limited by gravity.

I feel like maybe I'm missing something, but isn't this just a compactor? What am I missing? Does hydraulic pressure need gravity?

[avmich]

> Does hydraulic pressure need gravity?

If your compaction includes application of force vertically, top down, you need something opposing that force. On the Earth it's usually gravity, and on the Moon it could be the same, just the gravity on the Moon is ~1/6 the Earth one.

[Loughla]

Again, I think I'm lost with this. A hydraulic press needs gravity to oppose it? Like, the hydraulic cardboard compactor that pushes down on a bale of cardboard somehow uses gravity?

I am legitimately confused by what you're getting at. I feel like maybe we're not even talking about the same thing.

[HeyLaughingBoy]

> hydraulic cardboard compactor that pushes down on a bale of cardboard somehow uses gravity?

If the compactor is only pushing down, and it is not secured to the ground, then yes, it needs gravity to hold it in place. But most compactors are secured to a frame, so the force is produced between the hydraulic ram and that frame.

Most (all?) road equipment is held down by gravity: if it weighs 10 tons, then it can't apply more than 10 tons of downward force. However, if you need to apply more downward force, the easy answer is to secure your compactor to the ground.

[polishdude20]

No you're not missing anything. You're right. I'm saying that you'd need such a device on the moon because of the limited gravity. A compactor doesn't care about gravity.