Hydraulic pool cover that lifts off the pool and turns into a pergola... Am I nuts for trying this? 1

[mikefromgeorgia]

This looks like a simple solution to keeping my pool clean. Do you think that this kind of project can be something we simply have designed and built? It's a 20x40 pool, so I'd have two 11x41 foot roof sections that hydraulicaly lift off the pool into a pergola position. Apparently it hasn't been done since the 40's.

... Here it is. Youtube Video of it in action

 

[TehMightyEngineer]

Simply? No. Practical? Sure, I think this can feasibly be done if you're willing to spend the money on a robust hydraulic system. About the only warning flags in my mind are safety controls. I'd see about ensuring that if the hydraulics failed that it was securely locked into the upright position, and provide speed limiters so that it can't free fall onto anyone in the pool. Providing the ability to manually move it would also be a good idea in the event the power or hydraulics are out and you need access to the pool.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[mikefromgeorgia]

I'm basically committing to 4k either way to put a fence around the pool (we have little kids). It would be incredible if I could protect the water, the kids, and provide some shade in one shot so there is incentive to make it happen.

Are we talking 5k,10k, or higher? (diy after the design phase)

 

[Screwman1]

With the hydraulic system that you would need, the bracing in case of wind, controls, fabrication, etc., my first blush guess would be in the $100- 150K range for a one off system like that. That will need a very well engineered mechanism to work well.

 

[TehMightyEngineer]

I'd basically not even try to budget for something like this. It will cost whatever it costs. I'd only attempt to DIY this if I felt comfortable designing and installing hydraulic systems. That said, beyond the hydraulic system and the controls I don't see this costing too much more in materials than the pergolas (assuming labor is free as it's DIY). If you have to start hiring out to have someone help you build this then you're likely just better off going with a proven product.

I'd make sure you have access to basic machinist tools and welding equipment, a lot of the hydraulics will likely require custom brackets and supports for lifting the pergolas and will require some large forces to reliably lift them.

Definitely not trying to turn you off from this. Our shop has custom built our own concrete coring machine and vacuum truck. While it's not 100% perfect they came out well and definitely show that some heavy DIY projects can turn out well if you start out knowing how to do it and doing it right the first time.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[TehMightyEngineer]

Heheh, I don't think this will cost $100K but I do agree that this will be expensive. I imagine the hydraulics alone will cost a few thousand given how much force you will need with running multiple cylinders. Again, if labor and design time is free then this is probably a feasible project (especially if you can pick away at it over the course of a year or so). If you need this done quickly and can't provide your own labor or design time then I wouldn't attempt this.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[berkshire]

The only thing I dislike about the system in your Utube video, is that any trash on the cover is dumped into the pool as the cover raises.
I think a re-sequencing would be in order there to prevent that.
B.E.

You are judged not by what you know, but by what you can do.

 

[Archie264]

Something similar:

https://www.youtube.com/watch?v=WTctqB-co4k

 

[msquared48]

You're not nuts..., You're an Njinear.

Mike McCann, PE, SE (WA)

 

[mikefromgeorgia]

Awesome replies. Based on my rough estimate of 500 pounds, assuming it was aluminum I calculate 4000lbf. One big actuator indeed.

I can see it now. CNC=2,000 Aluminum = 4,000 Hydraulics = 5000, Home owner association = wtf is that.

I guess I'll just go for the pool cleaner and fence. Thanks guys.

 

[mikefromgeorgia]

Archie, That was awesome. It is much more logical as well due to simplicity. I wish I had enough space for it.

 

[MikeHalloran]

In the (first) YouTube video, there is only one hydraulic cylinder per side. The associated column lifts the other columns by means of the central longitudinal beam. ... which I think has to be tubular, in order to resist a twisting flutter of the roof.

The hinge detail at the top of the column, and the hinge offset from the column and from the roof beams bears close examination. Stability of the pergola in the erected position depends on the end of the column in one direction, and on gravity, i.e., location of the roof CG relative to the hinge line, in the other direction. I would worry about the roof flopping to a vertical position with the columns upright in certain wind conditions.

I might be more comfortable with a parallellogram arrangement, i.e., two columns, or a column and a strut, at each column position, both for stability in windy conditions and to keep the roof always level so the accumulated crap doesn't fall into the water.

Talk to a commercial awning builder about doing up the roofs as fabric stretched and tied over steel pipe frames, instead of joists and plywood and membrane roofing.

With roofs framed lightly, built and skinned on site, over a perhaps shop-built metal skeleton of truckable size, and tractor/logsplitter hydraulics, it should be do-able for way less than 100 large.










Mike Halloran
Pembroke Pines, FL, USA

 

[BUGGAR]

Take a look at the custom hood hinge mechanisms available in the car aftermarket. They have the right motion and can tilt the cover away from the pool. I suppose they could be counterbalanced like a car hood. Overbalance them and shoot the kids into the neighbor's yard.

 

[RHTPE]

Just wait for the first hurricane or microburst to arrive ....

The awning material should breakaway at some appropriate wind speed otherwise one could lose the investment in a rather unique setup.


Ralph
Structures Consulting
Northeast USA

 

[Ron]

RHTPE....gotta disagree on the breakaway design. In a high wind area that becomes windborne debris....not good. Design to withstand the necessary wind load.