Complicated pneumatic/hydraulic question.

[CherryK5]

Alright so i have a strange question that is difficult to explain.

So lets make it easy, I have a single acting hydraulic ram with a 1 in^2 piston area.
And a cylindrical tank with a 5 in^2 round face.

If i mount my tank vertically, half full of fluid, so that there is 5 in^2 of surface area on the surface of the fluid, and run that tank into my hydraulic ram, pressurize my tank to 1psi, will my ram receive 5psi of pressure?

Essentially i am asking if a tank of fluid, pressurized, will act as another ram.
With a virtual piston of sorts. the only variable missing is the actual piston itself.

I mean, i am pressurizing a non compressible surface, no different than a piece of steel.

Am i crazy??

 

[ryoken]

I'm not 100% sure I'm picturing this correctly, but no.. without a piston for the fluid to push, the fluid won't push... the 1 psi will just go to the top, and the fluid will remain at the bottom... it's not compressable, but it can certainly displace..

a quick paint pic of what your talking about would be a huge help..

 

[Avery4jc]

If I understand your question correctly, no. If you have a cylinder with fluid tied to your tank with fluid the pressures will obviously be equal. That being said say in an air over hydro situation it would take more volume of air to get the tank to 1psi than it would to get the cylinder to 1psi if they were separate systems. But tied together they'll have equal pressure overall.

 

[CherryK5]

Pretend i'm 3 years old and this is acceptable.

Meant 1 psi in the pic, Not 5

 

[cybrfire]

Unless I'm not understanding your description, I think you are designing a simple "air over hydraulic" system. It will push the fluid out.

It is what I have heard referred to a "soft" system.

The air is somewhat of a buffer.

EDIT, I don't think you'll have a pressure increase.

 

[ryoken]

that's how the pressurized hydraulic steering systems are set up on some boats... but I don't think you'd get the psi multiplication your talking about... think it's still 1 to 1... at least that how the boat ressy systems work iirc...

 

[CherryK5]

that's how the pressurized hydraulic steering systems are set up on some boats... but I don't think you'd get the psi multiplication your talking about... think it's still 1 to 1... at least that how the boat ressy systems work iirc...

See? once you think about it, it should make sense, but it doesn't!

Tossing around some ideas for an air over hydraulic suspension system.
Wanted to use a piston style accumulator as my "spring" so that i can keep fluid in the cylinders and keep a low air pressure with a small diameter ram (<200psi).

I dont have any accumulators, but tons of scuba tanks.

 

[cybrfire]

Pretty sure you'd have a decrease in pressure but the extension of the smaller cylinder would be really fast.

Switch it the other way around.

Small cylinder with 1 psi would push the bigger cylinder with greater force but extend it slower.

 

[CherryK5]

Pretty sure you'd have a decrease in pressure but the extension of the smaller cylinder would be really fast.

Switch it the other way around.

Small cylinder with 1 psi would push the bigger cylinder with greater force but extend it slower.

Lost me..

 

[cybrfire]

Take our hydraulic assist steering systems for example.

If you put a big cylinder on the axle it steers slow and has lots of power. Switch it around with a smaller cylinder on the axle, it steers fast and has less power.

Same thing here. Your "slave" cylinder is smaller than the "master" cylinder. It will have less power but respond quicker.

 

[ryoken]

we run ressy's like this on air over systems... we run them at 20 to 25 psi..

here's a similar brand installed...

you can see the Schrader valves at the top... it's why a hand bicycle pump is a common tool kept on bigger boats...

 

[CherryK5]

we run ressy's like this on air over systems... we run them at 20 to 25 psi..

here's a similar brand installed...

you can see the Schrader valves at the top... it's why a hand bicycle pump is a common tool kept on bigger boats...

So how does that work? i see it feeds the valve directly.
Do you know what the line pressure ends up being?

 

[CherryK5]

Kind of getting off subject.
Ryoken has a way of presenting cool boat stuff and intriguing people.


i guess i'll have to do some 'speriments.

 

[ryoken]

So how does that work? i see it feeds the valve directly.
Do you know what the line pressure ends up being?

I've always assumed the end line pressure is whatever air psi we run the ressy's at. and from cracking lines to bleed, etc on pressurized systems, I'd say that's a reasonable assumption...

there are quite a few configs for the hydro steering on boats, depending on what kinda helm it has.... dual stations complicates it even more, but generally that ressy keeps pressure to the whole system downstream, which also recirc's itself downstream... nothing ever refeeds the ressy...

 

[ryoken]

yeah, sorry to go off subject.. I just tend to apply things to what I know in my slice of the world... sometimes it gleens a bit of useful info to the original question.. sometimes it's a bunch of hooey...

 

[CherryK5]

I've always assumed the end line pressure is whatever air psi we run the ressy's at. and from cracking lines to bleed, etc on pressurized systems, I'd say that's a reasonable assumption...

there are quite a few configs for the hydro steering on boats, depending on what kinda helm it has.... dual stations complicates it even more, but generally that ressy keeps pressure to the whole system downstream, which also recirc's itself downstream... nothing ever refeeds the ressy...

Well that isn't promising...

I really just can't get my head around the fact that there is 0 difference between what i'm trying to do and a tradition ram other than the piston itself. which theoretically shouldn't make a difference. like i said, i'll have to just try it.

Force multiplication must happen!

yeah, sorry to go off subject.. I just tend to apply things to what I know in my slice of the world... sometimes it gleens a bit of useful info to the original question.. sometimes it's a bunch of hooey...

Haha, i hear ya man. Its like comparing a situation to a theoretical automotive situation. We can't help it.

 

[FrostBite]

Alright so i have a strange question that is difficult to explain.

So lets make it easy, I have a single acting hydraulic ram with a 1 in^2 piston area.
And a cylindrical tank with a 5 in^2 round face.

If i mount my tank vertically, half full of fluid, so that there is 5 in^2 of surface area on the surface of the fluid, and run that tank into my hydraulic ram, pressurize my tank to 1psi, will my ram receive 5psi of pressure?

Essentially i am asking if a tank of fluid, pressurized, will act as another ram.
With a virtual piston of sorts. the only variable missing is the actual piston itself.

I mean, i am pressurizing a non compressible surface, no different than a piece of steel.

Am i crazy??

The ram will receive 1 PSI but since the ram has 1/5 has much surface area it will move 5 times as far as the fluid in the tank; ie. The ram travels 5 inches, the tank fluid would drop 1 inch. Its a volume ratio not a pressure ratio.

 

[CherryK5]

The ram will receive 1 PSI but since the ram has 1/5 has much surface area it will move 5 times as far as the fluid in the tank; ie. The ram travels 5 inches, the tank fluid would drop 1 inch. Its a volume ratio not a pressure ratio.

I dunno... low post count usually means wrong...

Kidding. I hate to admit you might be right though.

 

[CherryK5]

But if so, how does force multiplication work?

 

[ryoken]

by the volume, small to big and vice versa..... pressure is always the same thruout a hydro system..