[snaef999]

This site has been a great resource for me throughout all of my hobby CNC efforts.

I am in the process of making a stage effect and believe hydraulics are needed to provide smooth quite operation of the effect. As everybody here has such a varied background I was hoping somebody here knew of a forum with the same kind of community as this one but with a focus on hydraulics. I will need some guidance and suggestions as I work out the mechanics of this one.

If anybody knows of such a forum, please let me know!

Thank you.
Scott N.

[jpgdesigns]

PM me I can help.

James

[Geof]

You will only get quiet operation if the hydraulic pump is a long way off or in a very well sound proofed chamber. Actually even then you may get noticeable noise because it transmits through the lines. Also flow control valves can be noisy and these generally have to be close to the working end of the system.

Before you commit yourself to any particular method I suggest you find some hydraulic installations to look at and listen to; not necessarily in the stage environment. Also find some electrically driven linear actuators to compare; these can be very quiet.

Linear actuators can be bulkier than a hydraulic cylinder with the same stroke and of course they are not capable of the same forces. On the other hand though the electric wiring is less bulky than hydraulic lines, the control system can be less bulky than hydraulic valves, and things cannot start leaking.

AN additional advantage is that the actuators can be readily repositioned just by unplugging cables which is a lot less messy than disconnecting hydraulic lines, and if low voltage actuators are used there is possibly much less hassle with safety issues.

[snaef999]

Thank you for the feedback. We are making a lift that will have a static load of about 600 pounds and a dynamic load of quite a bit more with two people dancing on it. The design calls for columns on all four corners so I was thinking about using cables and a hydraulic winch (taking all four cables back to a clue plate and using a single lift line on the winch). The lift will go down to basically floor level so I do not have any room underneath. The max height is about 25 feet so this is also why I did not consider cylinders.

I could create an elaborate pulley system and a very strong cylinder to take up all the cable slack but even with a 4' stroke and a 6+ reduction in pulleys the load on the cylinder would be almost 4000 pounds (static load). While this might be ok for the hydraulics it would put a higher fail point on all the other components. With a straight lift on the winch things just seem safer from a fabrication point of view.

I have thought about using electric winches or chain hoists, but anything variable speed is getting out of our price range. The manual speed control offered by a valve is appealing as it gives us more control over the lift speed.

We have about $2500 for the lifting force components. Noise is a concern but we can put the pump pretty far away in a basement. Sound transmission through the lines is something I had not thought about.

[Al_The_Man]

You might look at the modern methods of elevator control, they do not use lift cables any more, Hydraulics and guide rails etc with rack and pinion are a couple of methods.
Very quiet in operation also.
Al.

[Geof]

I think before you go any further you look up the regulations in your are regading elevators and lifting device rated for carrying people. Does your design incorporate failsafe latches that lock the elevator platform in position if a cable breaks or some other malfunction occurs? I think you might be playing with fire here, figuratively speaking.

[Geof]

If you do go ahead you might also consider long threaded rods at the four corners all driven at the top by a common drive chain running around four sprockets. This by design is self locking if the drive is lost and if chain failure occurs all the drives stop simultaneously.

But it is on your head, and the head of the engineer you get to sign off on any design.

[cam1]

I second with Geof:

People on a mechanical lifting device= hoisting device safety regulations. Play it safe, find out the rules and regulations before you proceed.Imagine how you would feel if you realized that you were responsible for injuring innocent people.

regards

[Al_The_Man]

I believe in most jurisdictions, you need to get the elevator inspection sticker from the local municipality etc.
This is what I had to go through when I rebuilt an ancient rope operated freight elevator for a guy that inherited it with the building.
If you are wondering about the rope, it was just a 2 or 3 floor elevator, and two ropes hung down through the cab top and you pulled on one for up, the other for down, what the rope did, was pull a 3 phase reverser in the loft, over manually.
I converted it to Push button control, but things like phase rotation detector had to be on the supply. This is in case someone inadvertently reversed the incoming power rotation.
Al.

[keyancnc]

Please look over the following web.

www.hydraulicsupermarket.com

[joe aiello]

HI Al; I think I have that elevator in my shop ( three levels). It is an Otis (circa - 1900) 5' by 5' floor, rope control, belt driven with babbitt bearings using a 3hp three phase motor. I like to update this to push-button and the appropriate motor. What did you do? What supplies and where to get them ? Is there a site that discusses this? Thanks --- joe