Automatic Table Lifts

Both solutions can be made "safe". The hydraulic solution using a "parachute" valve directly on the cylinder with a piloted by-pass to lower when pressure is on the "lowering" side of the ram.

If you use a "screw-jack" pay attention since most linear actuators are low friction with ball nuts and are not self locking. Either you choose a self locking design (intrinsically safe since self-locking is in the design) or a ball-nut solution with a safety brake normally closed and which will only open when actuator is energized.

Considering the load and the frequency of use I would suggest the mechanical self locking solution as more economical.

Commercially, since I guess you do not want custom built, try a motorcycle lift for service shops.

Do NOT disregard any of the safety advice you have been presented.

This product video from one of our customers may be on interest if you need compact and solid actuation: http://www.youtube.com/watch?v=zUjpNzCl0gE

The principle is a metal ribbon interlocking with a slinky and provides a much better actuation length/overall length ratio than hydraulics or ball screws.

They come in diverse sizes to fit small to theater applications.

Totally cool actuator! Thank you for your input! Kent

Thank you again for your insight! Can you tell me if their is a North American supplier of this actuator or do we deal with the Danish manufacturer? Kent

The manufacturer is based in Canada.

The company is http://www.pacocorp.com/

The new smaller actuators are not yet advertised on their web site.

Feel free to mention GiGa Concept sent you...

This solution is a little more sanitary.

yeah, like a James Bond device.

but still, I'd hate being asked by the wife to clean up under the table after a dinner with guests.

Langyaw's last comment makes a lot of sense. Who wants to eat on (basically) the floor. One further comment- Hydraulics have been suggested, but I would not think that the residual odor of hydraulic jack oil would be a palatable addition to the dining festivities.

consider pneumatic bladders - they are basically a heavy duty inner tube/light duty tire. They lift engine is just an inexpensive air compressor and a few valves. This type of lift is inherently pretty safe since most leaks are slow. You can enhance the leak rate with some restrictor orfices. A mechanical lock or toggle at each corner would also be desireable for safety.

A bladder with 4 square inches of cross section would give you 400 lbs of lift with 100psi air ( a standard shop air compressor). A 4'x4' bladder would give the same lift with much lower psi - probably a vacuum cleaner blower.

The compressors make in egneral a quite unpleasant noise during function.

OOOO ...... like airbags .... hm .. didnt think of that. I like it.

Thank You Everybody for your input! You have all been extremely helpful and this forum is indispensable. Kent

If you decide to use hydraulics go with a 3 stage alum cylinder and use veg. oil will be less odor and will cause less problem if it leaks. One of the problems i see with scissor acuators is leg room beneath, Possibly catch points for clothes or skin. Most of the short lifts ive seen lift up and slighttly to one side due to there design. Though I havent seen them all im sure. Hydrolicks would be the most expensive and difficult to install ... but it would be a simple mater to hide the cylinder from veiw and give the impretion it rose from the floor at the will of the button pusher. The pump would have to have to be quiet .... but shouldnt be hard the pressure needed would be minimal. They make a type of check valve that ingages if the flow rate is to high (cant remember what its called) .. if it where mounted to the cylinder itself it would not be able to "free-fall" in the event of a line breaking. These cylinders could be made at a resonable rate (for the industry) seeing as they could be bare alum requireing no plating or coating ... and a simple O-ring or similer type seal could be used.

There is your solution, feel free to contact us!

http://www.pacospiralift.com/i-lock-en.html

I like your concept! This table has to come straight up though. It is in the shape of an arc and adjacent to some bay windows with a spectacular view. Table itself is of old growth redwood slab several inches thick. The owner wants an effortless transision and with the arc allowing everyone at the table the view. I think we will explore the Katata or Gala actuator. I appreciate your thoughts and thank you for your input. K

Nice job!

You got a GA from me-

How about rigging this with a floor that would come up simultaneously?

Thank you,

I would only pursue further engineering on this if someone wanted it done... I live in an apartment with concrete floors.. so it won't be for me at this time.. but I just thought that the simple solution hadn't been suggested up to this point.. if you think about how your grandfather would have done it, I think that what I came up with was certainly do-able.

Getting the floor to fold out of the way certainly can be done, when its engineered in from the start, and as that link to the pool table shows, it works like a car sunroof.

I'm sure there are many other simple mechanisms, such as having the table top actually be the other side of the floor piece..and have it flip over as the table rises, etc.

As for a lever based straight rise, this can also be done, but will be more like sb's scissor lift. My point is that it doesn't have to be motorized, or electric, hydraulic, pneumatic, or any kind of machine system that can fail, need maintenance, smell...etc.

I think the simple solutions are typically elegant, and when the pieces are all hardwood, it would look awesome. I would balance it, so that simply releasing a latch would cause the apparatus to slowly rise, based on the counterweight. when done, unlatch, and a simple push will put it back in the floor. The whole thing would be a bit of a work of art.

Chris

btw.. this is my 1001st post.. happy day!

I appreciate your solution it in fact VERY logical, a proof of good engineering adapted to the environment.

It is also a way to think free of usual habits, very good!

at liftandlube.com we have some of the equipment that has been suggested here is a mid rise lift

http://www.liftandlube.com/Rotary_Revolution_RMR6_6_k_capacity_Mid_Rise_Lift_p/rot%20rmr6.htm

i would be carfull to use any device that does not have solid locks such as the locks in an auto/bike lift

if you want legs to hang underthe heavy table in the hole , otherwise save up for fake wooden legs and wheel chairs if the device fails.

here is the bike lift

http://www.liftandlube.com/Rotary_Revolution_RXLDT_1_k_cap_Motorcycle_Lift_p/rot%20rxldt.htm

something smaller that will give you the safety and positive locks is a rolling jack

http://www.liftandlube.com/Rotary_Revolution_RJ7000_7_k_capacity_Rolling_Jack_p/rot%20rj7000.htm

the above are Rotary Brand top of the Line Service Equipment for profesional installations and car dealerships there are lower cost units here in our home garage section

http://www.liftandlube.com/THE_HOME_GARAGE_s/135.htm

we dont have all the home garage section set up yet it is a new web site if you see a pro item and want a lower price give me a call i can set it up, for example a low cost 1000 pound table lift/jack can be had for less than $400 but that solution does not have electric or remote operation and does not have safety locks

These do not have all the needed capacity, but may be a good search start: http://www.selbyhardware.com/x1.htm