Introduction: Pneumatic Lift for Scenic Wagon
For a recent production of West Side Story, I needed to create a way to keep a steel wagon with a metal rear projection screen and projectors from moving while being used in a scene. We were using a space to perform in that we don't traditionally use, so we couldn't drill into the floor to use a cane bolt and commercial wagon brakes were not strong enough and were too bulky. The scenic designer wanted a clean look so we looked into pneumatic cylinders. We used Fabco TC-521-0, but if you call them they are great to work with and will help find the best cylinder for your use.
Step 1: Layout for the Pneumatic System
We estimated that the wagon and actors on it would weigh about a thousand pounds, so we purchased 5 cylinders, but may have been okay with just 4. The layout shows what we did. I decided on two tanks, Grainger Item # 21DH86, but you will need to decide on how much space you have to put them in and how often your cylinders will be used. The wagon moved about 10- 15 times per show and I didn't want a lack of air to be a problem, so two tanks. We could have refilled at intermission but opted to not have the noise of the compressor running.
Step 2: Fittings and Things for the Air Tank(s)
The air tanks came from Grainger with plastic plugs. I purchased brass fittings for the holes I wasn't using, Grainger Brass Pipe Fittings Item # 13Y816. I needed a way to fill the tanks, in hindsight I could have just built one of these, but I can now divide the system for future use. I used a 3/8" check valve, Grainger Item # 4DHV8, manual ball valve, Grainger Item # 58ZL14, and a quick connect air coupling, Grainger Item # 30E704, to fill the tanks from our portable air compressor. I added a pressure gauge, Grainger Item #4FMC7. The last thing was to tie the two tanks together, a push to connect fitting, McMaster Carr Item #5486K113, a wye connector, McMaster Carr Item # 5779K44, and the tubing was McMaster Carr Item # 51185K41.
Step 3: Control Valve
I used a two-position valve, that the fine folks at Fabco helped me find. Push and the wagon came off of the casters and pull to get it to release and back to the casters. The two lines on top were the supply line and the line to the muffler. The line on the bottom went to the manifold and brought air back to the control valve.
Step 4: Manifold, Getting the Air in and Out of the Cylinders
I purchased this at McMaster Carr Item #5469K133. I also purchased one at Automation Direct, but it got back ordered so got this one. I used pneumatic fittings from Amazon, https://www.amazon.com/gp/product/B00AXAY47W/ref=... found them cheaper than Grainger and McMaster Carr. They seemed to work fine. I used 1/4" tubing, https://www.amazon.com/gp/product/B00AXAY47W/ref=... also from Amazon. I chose black for my application but probably doesn't matter. I did buy a good cutter so my cuts were square, https://www.amazon.com/gp/product/B00AXAY47W/ref=...
I will note here you want as short of runs as you can for your tubing, without binding them. From the manifold to my cylinders the runs were all the same so the cylinders extended at the same time. I believe that one was a hair off because the sound of them lifting was inconsistent. The run from the control valve to the manifold was also as sure as I could make it, to keep more air in the tanks, longer.
I was guided by someone to not purchase a commercial muffler, as they wouldn't get the vented air out quietly. It was recommended that I get a plastic drink bottle, drill a hole in the cap, fill the bottle with cotton batting, insert the hose into the center of the batting and cut slits into the bottle. Worked great.
Step 5: Cylinders and Feet
I used Fabco Cylinders, once again the folks at Fabco helped me by doing the math to figure out bore size for the amount I was lifting. The drawing of the cylinder is used with their permission, the product number is on the drawing and on the first page of this Instructable. I built feet to keep the floor from getting damaged. The bolts and steel were things that I had in stock and the rubber I purchased from McMaster Carr, Item #8445K66.
Step 6: Lessons Learned
I am excited with the final product, though I wish I had known things beforehand.
1. Ask questions of vendors, most will be glad to help. If not try another vendor.
2. Comparison shop!!!!
3. The Air Storage tanks come with plastic plugs to keep dirt and moisture out, you have to find plugs to fill them and keep them from leaking. Teflon tape, even if they have a leak sealant applied.
4. Grainger and McMaster Carr can get you most things very quickly but don't test them. Amazon as well, but it does seem odd, to me, to purchase these pieces from Amazon. Not exactly sure why.
5. Dry fit and test before final installation.
6. I didn't push the pressure limits of my system, kind of wish I had before final installation, for my peace of mind.
7. Make your Instructable as you go!! I have read this so many times, wish I had heeded this. Maybe on my second Instructable.
8. This was my first pneumatic build, I am sure it isn't perfect but it worked for my application. I am still learning and am excited to use this system or parts of it again and to supplement it with more and different cylinders.
9. Take photos or video before you start taking it apart. Sorry for the lack of finished product and in action video.