Pneumatics

Robert F Jarvis

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Joined
Apr 8, 2017
Location
Sebring, FL, USA
Over at the Blue room I was given some ideas for moving some heavy gear on/off stage using pneumatic rams. Their references to suppliers were (naturally) based in the UK. Anyone here had experience using pneumatic rams to lower wheels etc.
 

RonHebbard

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Premium Member
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Jun 12, 2004
Location
Waterdown, ON, CA
Over at the Blue room I was given some ideas for moving some heavy gear on/off stage using pneumatic rams. Their references to suppliers were (naturally) based in the UK. Anyone here had experience using pneumatic rams to lower wheels etc.
@Robert F Jarvis A company in Stratford, Ontario; they've been mentioned a number of times here on Control Booth within the past year. A search of Control Booth should find them. In the next 45 minutes I'll look them up and post back.

@Robert F Jarvis Here's a link for you; Note restrictions imposed by our Provincial Government due to Corona.


Toodleoo!
Ron Hebbard
 
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DRU

Active Member
Joined
Feb 4, 2011
Location
Dayton/Cincinnati
The company Automation Fx (afx.bz) have pneumatic brakes and lift caster systems for sale. You can also purchase pancake cylinders, casters, or pads from McMaster-Carr and go a custom route if you wish.
 
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Malabaristo

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Joined
Jul 11, 2008
Location
Wisconsin
I'm a fan of Automation Direct for stuff like this. They've always had good customer service, and tend to be on the cheaper end of industrial suppliers. I've used their CLICK series of PLCs on a number of projects and you can't beat them on price vs capability.

One of my quarantine projects has been working on a design for pneumatic brakes. I went with the mindset that it's potentially a much more versatile approach than having to lift the whole wagon on/off of its wheels. The only downside is that a loss of air pressure results in the brake being released... but that seems manageable by being careful about avoiding leaks in the system. This is still a work in progress, but here's an idea of how it's looking:

WagonBrake.png


It's based around this cylinder, a couple pieces of t-track, some hardware, and one 3D-printed plastic part. Rubber on the bottom of the plastic foot adds a decent amount of friction. It's small and cheap enough that you can sprinkle a couple of them around as needed based on the size and weight of the wagon. The main thing I still need to figure out is how to shave off just a tiny bit more height so it can be used under a 2x4 framed platform with the casters we typically use (about 4.75" from the underside of the platform decking to the floor). I started with a little simpler design using a pancake cylinder, but I didn't like the way it put horizontal stresses on the rod & bushings. Plus that cylinder was about 3x the cost of this one...

Automation FX does have a similar product if you're looking for a less DIY solution: AirPux 2 Friction Brake
 

Van

CBMod
CB Mods
Premium Member
Joined
Jul 27, 2006
Location
Portland, Or.
For what it's worth; Years ago I discovered these guys that have a Halloween animatronics website. http://www.allscare.com/

They have GREAT Prices on Manifolds, solenoids, Cylinders controllers. Worth looking at. I used them for all sorts of on stage projects. Combining Their products with DMX Relay boards, or with the PLC controllers they have for sale is a great way to get things working.
 

Ted jones

Active Member
Joined
May 6, 2014
Location
Chicago
So maybe you add a coil spring over the piston rod that forces the brake to engage the floor and then use air to lift the brake. If you get an airline break, you can still move the wagon.

Ted
 

Malabaristo

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Joined
Jul 11, 2008
Location
Wisconsin
So maybe you add a coil spring over the piston rod that forces the brake to engage the floor and then use air to lift the brake. If you get an airline break, you can still move the wagon.
That was actually my original idea as well, but springs are trickier to get right. The amount of force applied depends on how far the spring is compressed, so it's a lot more touchy about the exact distance between the brake and the floor. With the brake being pneumatically applied, I can control the amount of brake pressure just by adding a regulator to the line and that pressure will always stay the same throughout the whole stroke of the cylinder. That seemed like a worthwhile benefit for being able to adapt to different applications in the future.

Here's what I thought would be a really clever first design:
WagonBrake (old).png

Since it was a double-acting cylinder, removing the spring was an easy switch to pressure-applied rather than pressure-released action. But as I said: the cylinder was a little too pricey, and the printed plastic foot didn't do as good of a job as I was hoping at transferring lateral forces to the body of the cylinder rather than the shaft. A slightly longer cylinder might have worked better if it meant not needing quite as deep of a notch in the foot to fit around the air connections.
 

Malabaristo

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Joined
Jul 11, 2008
Location
Wisconsin
Nice idea. I like and don't like the spring foot. But it probably would make it quieter too.
That's pretty much how I felt about it: I liked the simplicity and elegance of the idea, but wasn't satisfied with the actual result.

I don't have the parts yet to test this properly, but my plan for noise is to add rate limiter valves to the air line. That should let me slow down the movement of the cylinder without otherwise affecting how it behaves. The super sophisticated mock-up technique of pinching the tube just right seemed to indicate that I should be able to make it almost silent.
 

Ted jones

Active Member
Joined
May 6, 2014
Location
Chicago
A regulator will make that doable. Or even an open/close ball valve that you can set. The down side of the ball valve is that a pressure change will change your speed, where a regulator will keep the pressure even.