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RFQ: underwater scissor lift

rickg_la

Plastic
Joined
Apr 22, 2017
Hey all,
I'm looking for someone to help fabricate a scissor lift to be used in an underwater application.
It is to lift a 12' x 24' platform up and down 5', from underwater to just above the water.

We are looking for a hydraulic system that would use demineralized water rather than oil in case of leaks. The lift doesn't need to move quickly, if it took 60 seconds or slightly longer to move the complete distance, that's good. The total weight of the platform will not exceed 6000 lbs (it'll more likely be closer to 2000)

The lift should be stable at any height and will be in the raised position the vast majority of the time.

Also... if another type of lift seems to be a better option that you can help with, I'm all ears. it needs to be a clean system that has no exposed moving parts above the platform (otherwise I'b most likely be using a boat lift)

Many thanks,
Rick
 
Rick, this sounds like a really interesting project, but there's a huge amount of info that's still needed for anyone to take a shot at this. Like:

1) Seabed mount, fresh water, pond, industrial tank?

2) Subject to wave motion?

3) Subject to bio-fouling?

4) Uniform on non-uniform loading?

5) Human safe, or just inanimate object lifting?

6) Provisions for safety of electrical, hydraulic, or motion elements?

7) Anticipated lifespan and lift count?

8) And a whole bunch more...

BTW, with an area that large, a 60 second lift time is very fast (IMHO) for a bluff object moving through water, so the power requirements may be high just for hydrodynamic forces, let alone mass.

A better description of the requirements will help anyone contemplating working on this. Not to mention an idea of the budget!

Good luck, it sounds interesting...
 
Building a scissors lift as you have described would be relatively straight forward. Its the details that are going to complicate this project.

I huge issue that you have not mentioned is what the plan is for controlling sea life from building up on the structure and jamming it.

There is then the safety issue of using the traditional diver approach to scrub the sea life off at regular intervals.

The lift mechanism will also be a bit more complicated than a normal application. You have not mentioned if this is a fresh water or salt water application. Salt water would be the most difficult to handle corrosion wise.

Since you want everything underwater, that means the lift cylinders will be submerged 100% of the time. This means that the cylinder rods, seal assemblies, and cylinders themselves will need to be not only corrosion proof but also be able to handle the accumulating sea life without reliability issues.

You are choosing a very difficult approach, though probably very aesthetic. There are good reasons why most boat lifts are designed the way they are.

I would suggest to use a ballast tank approach. No moving parts except for how you would choose to do the stabilizer linkage. All you would need is some compressed air and some valves.
 
The ballast tank is a good approach
Another one is to use those air ride bellows A couple stacked on top of one another to get the right stroke Eighter use air or water
Bathlifts use them and use the waterpressure of the waterlines

Peter
 
sounds more like it would be for a theatrical or motion picture application. perhaps a theme park?

if it was "for the Mouse", I would think they handle that sort of thing completely in house, so not likely.

is it going to play in Vegas? for a Montreal based acrobatic troupe? (on review, at 12' X 24' most likely too small for them...)
 
I have a sunstream sitting in the lake just outside my window. There does not need to be anything above the platform, and platforms can be specialized for whatever boat, aircraft, etc. you wish.
They use hydraulic fluids the environmental police accept, but not water.
They are not normally as fast as implied in OP.
Note that while they are not scissors lifts, they are hydrualic operated beam lifts - not so terribly different.
Mine was damaged by a storm, but other than that seems OK, it's 6061 aluminum - in a fresh water lake.
By the way they're semi-custom built and range in size from small to 15K or 30K lbs and up....
 
just a note to the OP, RFQ isn't remotely what you are asking for in your post, you seem to be at an early design phase, "bar napkin phase" is the best description.

REQUEST FOR QUOTE happens when you have a complete set of drawings for the build in question, "signed off" by all parties.

unless I misunderstood, and you do have drawings, using that term here sends up a red flag that you have no idea what you are doing. not to be rude, but just sayin'.

you can get lots of good information here,(for free, take it for what its worth!). there is a wealth of knowledge, but you really can't expect much from such a vague description of your application.

the type and condition of the water, and the expected cycle rate and lifetime, the safety systems required ( will it carry humans?), the possible governmental and/or regulatory jurisdiction.....just a few things missing... could affect price by a factor of 20 to 60 (or even 100) X easily.
 
Hello Everyone.
This thread has died off but I am essentially asking the same question.

I'd like to build a fresh water pool that has a floor that would lift out of the water and sit pool edge level when not in use. The floor would be out of composite decking (or something else) and would match the surrounding deck and be able to hold people sitting/standing/walking.

I'm just at the napkin stage right now and trying to figure out the best method for lifting the platform. Basically starting to gather information so when I reach out to businesses/individuals I'll have a better idea of what and how to communicate.

Roughly thinking a 12'x 24' pool. 46" deep when standing on the platform.

Platform would not lift people but should have the stabilty and holding power so people could stand on it at any point.

Not overly concerned with the speed of the lift rate.

I expect it to be in the up/extended position most of the time. I'm in Michigan so we get like 3 months of pool time. Winter and a frozen pool is another consideration.

Thoughts on a good lifting method?


If there is a better place to ask, please let me know.

Thanks.
 
One idea that might work
Airspring bellows A couple stacked on top of one another to get the right stroke
6 or 4 of them
Use water from the pool
Bathlifts use them and use the waterpressure of the waterlines
In the topposition lower the platform on some dowels or so that come out of the platform onto a ridge in the pool to stabelize it all Also actuated with airspring


Peter
 
Hi, i'm also intrested in a similar project I want to build a pool 3m x 5m x 2m deep.
With floor that comes up and cover the water when not in use.
Nick did you use the air spring idea?
I'm a little scared of putting air springs one on top another, did you find another solution? also, does air springs freshwater safe?
Or I'm scared with no reason?
 
Another even better idea perhaps is to use a tank as the floor (Or a frame with rubber blathers )
Fill with water to lower it
Blow it out with air to raise it You could use a ring blower for that perhaps
Then some vertical dowels at the corners and sidesto position the tank when raised
To keep it level during raizing one could use the same cable system used in some of the car lifts
Give it enough upwards force to seat the dowels properly so it does not move with people on it
Or lock it in place perhaps

Peter
 
Another even better idea perhaps is to use a tank as the floor (Or a frame with rubber blathers )
Fill with water to lower it
Blow it out with air to raise it You could use a ring blower for that perhaps
Then some vertical dowels at the corners and sidesto position the tank when raised
To keep it level during raizing one could use the same cable system used in some of the car lifts
Give it enough upwards force to seat the dowels properly so it does not move with people on it
Or lock it in place perhaps

Peter

Hi peter, thank you for your help!
I didnt understand your solution.
Lets say that the floor is a frame coverd with a deck, I picture the frame in my head with two big holes so water can come down when the deck is coming up.
For the second part, what do I blow with air for the floor to come up?
 
Make the floor as a flat tank If it is filled with water it lies on the bottem
If you empty the tank by blowing air in it it will rise to the surface
A bit like a submarine

Peter
 
Even swimming pools with filtered chlorinated water need regular cleaning, and it's a lot of work even for a smooth surfaced tank.

If you put any kind of gizmo permanently into the water, you're going to have trouble.
And a LOT of work.

Putting aside huge construction costs, is your idea worth the maintenance cost that it will incur?
 
Hi, i'm also intrested in a similar project I want to build a pool 3m x 5m x 2m deep.
With floor that comes up and cover the water when not in use.
Nick did you use the air spring idea?
I'm a little scared of putting air springs one on top another, did you find another solution? also, does air springs freshwater safe?
Or I'm scared with no reason?
I've seen ones where the cover / deck rolls in from the side over the top of the pool.

None of the maintenance issues.
 








 
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