# Pneumatic Wheel Lowering



## Robert F Jarvis (Feb 24, 2020)

We have some heavy items that need to be moved across stage to be danced on! We want a system, where the crew could operate a button that activates some pneumatic cylinders to push the wheels down an inch. And similarly retract them once in place leaving the platform stable. Has anyone used anything like this and if so can you let us have details of the apparatus you used please.


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## almorton (Feb 24, 2020)

Not pneumatic, but we've built trucks that have lever operated wheels which retract once the truck is in place.

I have a feeling of deja vu ...


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## Robert F Jarvis (Feb 24, 2020)

I think if the levers could be out of view and easy to operate this would be a simpler solution. Do you have any details of the device/ hardware you used?


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## DRU (Feb 24, 2020)

Automation FX (www.afx.bz) sells pneumatic brakes and lift casters. You can also make your own for a similar price using pancake cylinders from McMaster.com.


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## BillConnerFASTC (Feb 24, 2020)

Just plan for the noise.


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## Robert F Jarvis (Feb 24, 2020)

AFX looks good. And thanks for the heads up on noise issues.


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## almorton (Feb 24, 2020)

Our trucks use nothing you wouldn't find in a regular workshop - wheels, bar, bolts and wood. Just a bit of ingenuity required to make them work. Each one is different yet similar, IYKWIM.


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## bobgaggle (Feb 24, 2020)

I second AFX. I've built my own systems before but AFX is hands down the way to go. You might feel it in your wallet, but its as plug and play as you can get for a system this flexible... Laine even color codes all the connections for you. you literally screw down the components wherever they fit on your unit, and cut the hose to length. so easy.


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## IMLICHTMAN (Feb 24, 2020)

All good ideas. You could also consider mounting your casters on hinged or toggled plates and using conventional air springs (think air-ride truck bags) for the lift. Advantages would be low cost, low parts count, lots of lift force in a small envelope. Disadvantages would include your "NRE" cost for the hinge/toggle caster mount and clearance for the air fittings on the top or bottom of the mechanism.


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## microstar (Feb 24, 2020)

This is also what air casters do plus you have the bonus of frictionless wagon movement. If the wagon is big enough to house an air tank, you don't even have a trailing hose.


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## BillConnerFASTC (Feb 24, 2020)

microstar said:


> This is also what air casters do plus you have the bonus of frictionless wagon movement. If the wagon is big enough to house an air tank, you don't even have a trailing hose.


Love air casters but require a fairly smooth floor without wide seams or gaps, and may be noisy. The "pharting" could be worrisome.


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## MarshallPope (Feb 24, 2020)

It's also worth thinking about if you prefer the casters or brake pads to be on the cylinders. If the casters are pneumatic and you lose pressure, the unit may be stuck on stage. Inversely, if you have pneumatic brakes and you lose pressure, it may move inadvertently if someone is dancing on it, posing a safety risk.


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## Crisp image (Feb 25, 2020)

Dare I say it but I am using electric actuators to lower electric motors to the stage so an item can be manually pushed while the drive wheels are retracted and then become automated when lowered. This could be used for a show like... let me see....... something to do with a wizard and a green elixir. All amateur production of this show but it will work. If space permits under wagon then some sort of mechanical lift would work to lower wheels to the stage for movement. 
I get my actuators from places like lift chairs and old hospital beds. They are 24v but will work on an 18v Makita battery or even a 12v battery. Just not with the original control box they don't like such low voltages

Regards

Geoff


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## kicknargel (Feb 25, 2020)

MarshallPope said:


> It's also worth thinking about if you prefer the casters or brake pads to be on the cylinders.


More considerations on this question: if lifting the casters the whole unit does a little clunk up and down when shifting states. WIth brakes you can set the pressure so the brakes push into the floor without lifting the unit. We've done this with 3-4" diameter pads with soft rubber pushing into the floor. It's still not AS secure as lifting the casters entirely.

And ANOTHER consideration: typically a large unit may have caster about 4' OC or more. That can mean a lot more lifts on casters vs. brakes. Or you frame the base unit to be stiffer and need fewer casters. If it's not moving with people on it that helps; then when it's playing the frame is on the ground and well supported.

Lastly, I remember a DIY version in Technical Design Solutions for Theatre. Must be in volume 3 because I don't see it in 1 or 2. Everyone must own these books. I'm buying v3 now (I do have the original subscription pages).


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## RonHebbard (Feb 25, 2020)

kicknargel said:


> More considerations on this question: if lifting the casters the whole unit does a little clunk up and down when shifting states. With brakes you can set the pressure so the brakes push into the floor without lifting the unit. We've done this with 3-4" diameter pads with soft rubber pushing into the floor. It's still not AS secure as lifting the casters entirely.
> 
> And ANOTHER consideration: typically a large unit may have caster about 4' OC or more. That can mean a lot more lifts on casters vs. brakes. Or you frame the base unit to be stiffer and need fewer casters. If it's not moving with people on it that helps; then when it's playing the frame is on the ground and well supported.
> 
> Lastly, I remember a DIY version in Technical Design Solutions for Theatre. Must be in volume 3 because I don't see it in 1 or 2. Everyone must own these books. I'm buying v3 now (I do have the original subscription pages).


*If we're going to swerve into DIY concepts, try this one*: 
I'll provide dimensions purely as an example, smaller or larger boxes and inner tubes may be substituted. 
Build two plywood boxes. Each box has a bottom and four sides, no top. 
Glue and screw the boxes, make their joints REALLY solid. 
Size and construct the two boxes such that one box inverts and slips over the other. 
Make one box deeper than the other by the depth of the casters on the lower box. 
CLEAR AS MUD SO FAR; I'll try and clarify: 

Think of it this way: 
Box 1; Approximate dimensions for illustrative purposes only. 
30" x 30" x 8" deep. 
Imagine box 1 sitting on the floor, open side up, four good quality 3" or 4" swivelling casters on the bottom. 
Imagine box 2 slightly larger than 30" x 30" x 8" deep + the height of the casters on box 1. 
Invert box 2 over box 1 and set it down. 
Box 2 is now inverted and resting firmly on the floor. 

Box 1 is now out of sight inside of box 2. 
When you load (build you set on top of) box two, it doesn't want to slide or tilt because it's sitting inverted directly on your stage. 
Build multiple pairs of boxes to support larger sets. 

*HERE'S THE TRICK*: 
Inside of the two boxes place a suitably sized inner tube, remember inner tubes from the era before tubeless tires? 
When you inflate the inner tube, it expands in all directions. It can't expand very far laterally because you've sized it to fit your boxes AND you've constructed, glued and screwed both your boxes to withstand the pressure of the inner tube. 

Thus confined, the only direction the tube can expand is vertically; when it expands vertically, it lifts box 2 clear of your stage floor placing all of the load on the four GREAT casters you've securely attached to the bottom of box 1. 
Your set is now elevated on your DIY air-ride and free to be pushed about your stage. 
Releasing air from the inner tube deflates the tube and box 2 again returns to its inverted position resting directly on your stage. 

*NOTES*: 
*1*; You need to construct, glue and screw both your boxes to withstand the pressure of your tube trying to expand in all directions. 
*2*; You need to accommodate getting air into your inner tube while it's trapped within both your boxes, this will mean providing a gap and / or slot(s) to facilitate the passage of an air hose. 
*3*; You need to be able to fill the inner tube, retain its air under pressure, and release its air on cue when desired. 

*No, I didn't dream this up by myself*. In the late 1970's a touring production toured our large soft-seater. 
The show involved two complete sets each approximately 40' wide x 20' US / DS. 
Each set included its own floor, carpets, walls, doors, stairs, second levels, escape stairs for performers, furniture, appliances and practical lights. 

There were multiple scene changes between the two sets. 

The road crew dealt with all aspects of the air, its couplings, valves and muffled exhausts. 
Thirty or forty of my local IA brothers rolled one complete set into one wing while the second set rolled on from the opposite wing. 
Being the Assistant LX, I had it easy only having to page cables for practical lights and keep them clear of the feet of my grunting brethren. 
We'd heard about the production before it arrived, including its requirements for local crews. We all giggled and snickered during the in. 
We weren't snickering when we watched how well it all worked performance after performance nor were we snickering counting the money we made while watching the show and only doing any real work during scene changes. 
That's my DIY air ride tale and I'm sticking to it. 
Toodleoo! 
Ron Hebbard


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## DRU (Feb 26, 2020)

Pneumatic brakes can be quite strong. I worked briefly for a company that used homemade lift casters, which were quite noisy when going up and down. I bought a stemmed pad from McMaster and switched the casters over to brakes for a 4x4 platform about 18" tall with a 6' ramp. I tested it by running and jumping sideways onto the ramp, and it did not move. Flick a switch and one person could move it with ease.

But it does beg the question: if the pneumatics failed on either lift Casters or brakes, which situation would be the better one to be in? Unable to move with the lift casters or free wheelin' with brakes?


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## kicknargel (Feb 26, 2020)

Ron, that is essentially the technique in Technical Design Solutions for Theatre. Thanks for describing.


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## sk8rsdad (Feb 26, 2020)

DRU said:


> which situation would be the better one to be in? Unable to move with the lift casters or free wheelin' with brakes?


Free wheelin' with brakes is almost always better. There are lots of ways to improvise something to temporarily keep it from moving but precious few ways to move something that is too heavy to lift.


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## RonHebbard (Feb 26, 2020)

kicknargel said:


> Ron, that is essentially the technique in Technical Design Solutions for Theatre. Thanks for describing.


 * @kicknargel* The tour used swivelling casters, it took a little dance to swing the casters around; after a rehearsal or two, my IA brethren had the two-step routine perfected. 
Toodleoo! 
Ron Hebbard


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## thecoin (Feb 26, 2020)

AFX casters have changed the way we build things.
They solve all of our "can they dance on it" questions. Basically if feet touch it, and it moves it gets air casters, tables/desks/half the set/ect..
Everyone should own these things and throw all but two of their toggle brakes away.


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## TimFrancis (Feb 26, 2020)

There are several articles in Yale Tech Briefs, USITT Tech Expo catalogs and USITT Technical Source Guide about using pneumatic cylinders as platform lifts or brakes.
A Technical Source Guide (early 90's?) and Exhibit #2 from the 1995 Tech Expo(some words are jumbled from scan conversion) are attached.
As Nick mentioned, Technical Design Solutions for Theatre (Yale Tech Briefs) Vol. 2 p.200 has an example as does Vol. 3 p246 and p249.


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## Richard Green (Apr 4, 2021)

@thecoin :
Throw away the toggle brakes? Heresy!!! Just take them away from the stage carps and give them to the scenic carps to build jigs with. Those things are the crap.


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## Richard Green (Apr 4, 2021)

huh. Apparantly "Those things are the sh*t" got autocorrected to "Those things are the crap" which is not a phrase that makes sense in English. Weird.


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